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HomeMy WebLinkAboutWPO201400008 Plan - E&S Stormwater Management Plan 2014-05-15 „.., R 1 vA NN A ________.,, _ ,.....„. \ WATER & SEWER AUTHORITY 1/4\--•-i Granular Activated Carbon Contactor Facilities at the Crozet Water Treatment Plant Major Amendment to Approved Site Development Plan # 199900043 Erosion Control Plan and Stormwater Management Plan Including Erosion Control Narrative and Calculations, Stormwater Analysis, and Related Specifications Submitted to: County of Albemarle May 2014 �,, ,, t of 4 1:7 ,fr‘/„4,-;!� 0 Z 2 Z I,,< ,, o,>,rc . 2 5 C�5 M- HAZEN AND SAWYER Environmental Engineers & Scientist: 4011 WestChase Boulevard, Suite 500 Raleigh, NC 27607 NARRATIVE REPORT INTRODUCTION The Rivanna Water and Sewer Authority (RWSA) is proposing upgrades to one of their existing water treatment plant(WTP)facilities to meet recent US EPA regulations addressing disinfectants and disinfection byproducts (DBPs)and microbial pathogens. The WTP is located west of the City of Charlottesville in the town of Crozet. The Crozet Water Treatment Plant sources water from the Beaver Creek Reservoir. To meet DBP regulations, new carbon contactors containing granular activated carbon (GAC)will be added to the plant between the processes of filtration and primary disinfection. The Crozet WTP resides within the jurisdiction of Albemarle County, and all necessary permits will be coordinated with the County. All proposed construction will take place within the Crozet WTP property; no construction will occur outside of the property boundaries. The site is located within the Albemarle County Entrance Corridor and as a result is subject to the County's Architectural Review Board requirements. The disturbed area for these improvements is approximately 1.12 acres. Any excess and unsuitable soil will be stockpiled onsite by the contractor with the option of unsuitable material to be disposed of in an approved location with all required permits to be acquired by the contractor. Erosion and sediment control measures will be used to limit erosion and contain sediment from the construction and cleared areas prior to the establishment of vegetation. SOILS Two soil types exist on site. These soils have been identified and classed by the Natural Resources Conservation Service (NRCS), and are detailed below. 36B— Hayesville Loam The Hayesville series soils, a well-draining series, exist predominantly on hillsides and typically have a depth to the water table of over 80 inches. Hayesville series soils originate from residuum weathered from granite and gneiss. Slopes range from 2 to 7 percent. 37C3 — Hayesville Clay Loam This soil portrays the same characteristics as the Hayesville soil listed above, yet contains predominantly clay loam soils, rather than loam soils, within the first 7 inches. Slopes range from 7 to 15 percent and are severely eroded. ADJACENT AREAS Land use immediately surrounding the property consists of residential development and rural areas. The property is bounded to the west by residential lots, and on all other borders by rural areas. The parcel shares its northern boundary with a VDOT public right-of-way, occupied by Three Notch'd Road. All minimum yard requirements are met for this parcel along its boundaries. EROSION AND SEDIMENT CONTROL MEASURES A majority of the erosion and sediment control devices and measures have been designed and Nyaw- placed in accordance with the Virginia Erosion and Sediment Control Handbook (VESCH), Third Edition, 1992. Temporary measures will be used to limit erosion and contain sediment from cleared areas prior to the establishment of vegetation. Once construction, including all structural measures, is complete and permanent vegetative cover has been established, these measures may be removed with approval from the engineer. Vegetative cover for disturbed areas will consist of grasses as recommended by the Virginia Erosion and Sediment Control Handbook. See the Plans and Specification Section 02910 — Final Grading and Landscaping for the proposed Seeding schedule, attached. The temporary measures proposed for this improvement include silt fence, construction entrances, and temporary seeding measures as required. The above devices will filter sediment from runoff to prevent sediment from being deposited off-site, while the temporary seeding will limit erosion during construction activities. Permanent measures proposed include permanent seeding. See Specification Section 02276 — Erosion and Sedimentation Control and Section 02910 — Final Grading and Landscaping for further details on these temporary and permanent measures. Temporary Stabilization A majority of the temporary sediment and erosion control measures were designed and chosen based on criteria from the Virginia Erosion and Sediment Control Handbook (VESCH). Stabilization construction entrances/exits and silt fence are designed in accordance with the guidelines established in VESCH Sections 3.02 and 3.05. Temporary seeding measures were chosen as per the recommendations of VESCH Section 3.31. Temporary rolled erosion control mat was designed in accordance with the procedures outlined in Section 3.36. Permanent Stabilization Upon completion of the project, permanent vegetative plantings will be used to achieve stabilization of the site. All temporary erosion and sediment control measures will be removed once the site has been stabilized. All permanent vegetative plantings conform to those specified in the VESCH Section 3.32. See Specification Section 02910 — Final Grading and Landscaping, attached, for the proposed seeding schedule. Erosion Control Sequence 1) No demolition, construction or land disturbance activities may begin until all perimeter erosion control measures have been installed as per Contract Drawings. If clearing is required for installation of a particular measure, all other measures shown shall be installed first; clearing of the land necessary may then proceed. 2) Once all measures have been installed, the site shall be cleared and grubbed as necessary within the limits of disturbance as per the Contract Drawings. Efforts shall be made to minimize the amount of cleared area exposed at any given time. 3) Once clearing and grubbing is complete, any necessary topsoil stripping may begin. Topsoil shall be stockpiled on site in the stockpiling areas per the Contract Drawings. The stockpile shall receive such temporary seeding measures as may be required. Any soil taken offsite shall be stockpiled at locations with all required permits. If offsite location does not have all required permits, the contractor is responsible for obtaining any required permits. 4) Demolition, earthwork and construction operations may begin once topsoil has been removed and stockpiled. 5) Once perimeter erosion control measures are in place, construction activities for the new GAC facility and proposed roadway may begin. 6) All pipes shall be installed in accordance with standard construction techniques. Only the length of trench in which pipe can be installed in one day's time shall be open at any time, with spoil material placed on the uphill side of the trench. Piping shall be capped at the end of each day's work to prevent sediment from entering. The trench shall be backfilled at the end of each day's work and the disturbed area seeded and mulched within seven (7) days of backfill. 7) Temporary soil stabilization shall be applied within seven (7) days to denuded areas that may not be at final grade but will remain dormant for longer than fourteen (14) days, except for that portion of the site on which work will be continuous beyond fourteen (14) days. 8) Once construction activities are complete, final grading may begin. 9) Upon completion of final grading, permanent seeding, mulching and fertilizing measures shall be employed on all disturbed areas as per Section 02910 — Final Grading and Landscaping. Permanent soil stabilization shall be applied within seven (7) days after final grade is reached on any portion of the site. All erosion control measures shall remain in place until the entire site has been stabilized. 10) Upon completion of stabilization of the watershed, remove all accumulated sediment and excavate bioretention area to proposed depth. Use relatively light, tracked equipment to avoid compaction of the basin floor. After grading is complete, deeply till the basin floor with rotary tillers to provide a well-aerated, highly porous surface texture. Install the bioretention gravel, sand, and fill media as noted in the Contract Drawings. Install vegetation and ground cover for the bioretention area. 11)Once permanent stabilization has occurred, temporary sediment control measures shall be removed. Any areas disturbed by the removal of these measures shall be returned as closely as possible to original condition and seeded, mulched and fertilized as per Specification Section 02910. Maintenance and Sediment Disposal All sediment and erosion control measures shall be inspected upon installation, at least once every fourteen (14) days and within 48 hours following any runoff-producing rainfall event. Repairs to, or replacement of, measures shall occur immediately if necessary and accumulated sediment removed as needed. Sediment shall be removed from all erosion control measures when the sediment storage volume of the measure has become 50%full. All removed sediment shall be disposed of in an approved manner at the stockpile location or a location to be designated by the Engineer or Owner. Steps shall be taken at the disposal site to insure that further sediment transport does not occur. All disturbed areas shall be permanently seeded as soon as possible, but in no case later than seven (7) calendar days after construction activities are complete. Areas shall be seeded, fertilized and mulched in accordance with the Seeding schedule in Section 02910—Final Grading and Landscaping, of the Specifications. STORMWATER ANALYSIS Introduction This stormwater analysis has been prepared in response to the Crozet WTP improvements. The material provided in this analysis evaluates how the proposed project will affect stormwater runoff and nutrient export from the site. All material provided in this analysis has been prepared and is presented in general accordance with the guidelines outlined in the Albemarle County Water Protection Ordinance. This analysis focuses on both stormwater quantity and quality. The area of the study currently consists of approximately 2.63 acres, a combination of grassed areas, buildings, tanks, and other impervious cover such as roadway, sidewalk, and gravel. The entirety of this area drains to the southwest corner of the property, and is ultimately collected in the Licking Hole Basin, located southwest of the property. A majority of the proposed Crozet improvements will be constructed in an area of the site which is currently gravel pavement. The improvement plan includes decreasing the amount of existing gravel and restoring the area to maintained grass. As a result, the overall impervious area for the site will decrease and an overall decrease in runoff is anticipated. Our project is located within the Drinking Water Watershed and is categorized as a redevelopment based on the Albemarle County Simple Method spreadsheet. As a result a stormwater BMP appropriately sized to treat 0.16 lbs of stormwater pollutant is needed to offset the proposed improvement. Methodologies and Procedures The primary task of this stormwater analysis is to determine the degree of stormwater treatment required for the proposed project for quantity, quality and adequacy. The extent of this analysis accounted for the following factors: the location of the project site, the size of the site respective to the total watershed, and the degree of proposed development. Water Quantity Concerns Channel Protection (VA Minimum Standard 19, Albemarle County Code 17-314) On 4-10-14, Hazen and Sawyer conducted a site visit to access the existing channel receiving runoff from the Crozet Water Treatment Plant(WTP) property. Per the County's recommendation, we estimated cross sections and took photos every 50' —or for each change of condition - along the channel as it drains to the existing detention pond (Appendix V). Based on our measurements in the field we were able to record the approximate side slopes and depths at each cross section, shown in the captions in the field notes. After reviewing the pictures and available contour data we developed estimated depths and widths for each cross section to be used in the channel flow calculations necessary as per MS-19 regulations. As stormwater leaves the WTP site at a point on the western boundary of the property, it flows along a barely defined existing channel within the adjacent residential neighborhood. The existing channel becomes more clearly defined at approximately STA 0+50 downstream of the WTP property's discharge point. No visual signs of erosion or flooding were noted until STA 1+59, where minor channel bed erosion is evident. At this point, flow from approximately 0.5 acres of the residential property of the existing channel enters the channel as sheet flow. We observed increased erosion at STA 2+50 where a stormwater channel beginning at a culvert draining from the northern residential development joins the subject channel. In the channel's current state, it appears the channel is adequate to handle flow from the WTP site as erosion does not occur until additional flow from the surrounding residential development also enters the channel. As we have discussed previously, the stormwater BMPs proposed as part of the WTP site upgrade, combined with a reduction of the overall impervious surface on site, will result in a decrease of the peak flow to the existing channel. When modeled, this reduction in flow is approximately 0.17 cfs for the 2- yr storm and 0.22 cfs for the 10-year storm. This lesser flow will reduce the erosion potential within the existing channel. Our calculations (Appendix V) show the channel to be adequate for capacity and velocity for the 2- and 10-year storm events for a distance of 159' feet downstream of the RWSA property. After reviewing the available data on the County's GIS website and discussing this matter with RWSA, it has been determined that the downstream residential development was constructed sometime around 2003, well after the development of the Water Treatment Plant. Without disregarding the requirements of MS-19, it must be noted the WTP predates the residential development. The evidence from our field visit presented here indicates it is the addition of runoff from the surrounding residential development which causes erosion in the existing channel. Also, it appears that RWSA is in compliance with one of the Virginia DCR Technical Bulletin's (4VAC50- 30-40.19.c) listed of suggestions for channels deemed in inadequate. Item number three from this list suggest that applicants shall: "(3)Develop a site design that will not cause the pre-development peak runoff rate from a two-year storm to increase when runoff out falls into a natural channel or will not cause the pre-development peak runoff rate from a ten- year storm to increase when runoff falls into a man-made channel" Given the result of our calculations presented above, combined with our observations of no erosion in the channel immediately downstream of RWSA property and noting the proposed project improvement will result in a net reduction in the total runoff and peak flow rate from the WTP site for the 2- and 10-year storm, it is our conclusion that the existing downstream channel is adequate to handle stormwater flow form the WTP property. As noted above, project construction will result in a slight decrease in the total impervious area at the site. With this proposed decrease in impervious area, 2-year and 10-year peak discharges from the site will also decrease. No quantity controls are proposed, as the site meets criteria as outlined in Section 17-314 (A) and(B) of the Albemarle County Code of Ordinances. Calculations are found in Appendix V. Channel Protection (9VAC25-870-66) "' According to Paragraph B (3) of Section 66, Chapter 870, Agency 25, Title 9 of the Virginia Administrative Code (9VCS25-870-66), natural stormwater conveyance systems must be checked for the 1-year, 24-hour storm for compliance under the following methodology: QDeveloped< I.F.*(QPredeveloped* RVPredeveloped)/RVDeveloped,where QDeveloped =Allowable peak flow rate of runoff from the developed site I.F. (Improvement Factor) = 0.8 for sites > 1 acre or 0.9 for sites <_ 1 acre QPredeveloped = Peak flow rate of runoff from the site in the pre-developed condition RVPredeveloped = Volume of runoff from the site in pre-developed condition RVDeveloped = Volume of runoff from the site in the developed condition An overall curve number (CN) was calculated for both the predeveloped and developed conditions. From these curve numbers RVp redeveloped and RVDeveloped (without treatment) were calculated using the formula below: Q (Runoff Volume) = RA Where: A= Drainage Area R(Runoff Depth) = (P — Ia)2 (P + Ia —S) N P (Precipitation) = Precipitation depth of 1-year, 24-hour storm event(3.04"*) 1000 S (Storage) = N — 10 Ia(Initial Abstraction) = 0.2S * NOAA's Nation Weather Service precipitation estimates. To account for the runoff reduction credit given to the proposed bioretention cells, treated drainage areas for the three bioretention cells were entered into the Virginia Runoff Reduction Method (RRM) Spreadsheet. The spreadsheet calculates an adjusted RVdeveloped and curve number (CN) based on the developed conditions. The SCS Graphical Peak Discharge Method was used to determine QPreaeveloped and QDeveloped. A composite curve number based on the predeveloped conditions was used to calculate QPreaeveloped; the adjusted curve number was used to calculate Qoeveloped. As the site is greater than one acre, an improvement factor (I.F.) of 0.08 was used in the above equation. The above equation determined that the Qoeveloped must be less than or equal to 3.74 cfs. At QDeveioped = 3.73 cfs, the site meets requirements of 9VAC25-870-66. Calculations can be found in Appendix VI. Water Quality Concerns New The point of analysis for the pre- and post-construction drainage areas is a depression in the southwest corner of the property, adjacent to the existing water storage tank. Based on the calculation of the Albemarle County Simple Method BMP Spreadsheet, the pre-construction drainage area to the point of analysis is 36% impervious; therefore, the project is considered a redevelopment because it is over the 20% impervious threshold. As shown in the Albemarle County BMP worksheet, the post-construction impervious area draining to the point of analysis is 35%, lower than the pre-construction impervious percentage. The Crozet WTP is located within the Drinking Water Watersheds of Albemarle County. According to the Albemarle County BMP Worksheet, this project which is located in the drinking water watershed and categorized as a redevelopment is required to treat 0.16 lbs of stormwater pollutant, which computes to a required 13% removal of phosphorus. Therefore, stormwater quality treatment is required. Proposed Bioretention Cells Three bioretention cells (BRCs) were proposed to treat the needed pollutant removal rate associated with the proposed development. The bioretention cells were sited in an effort to treat a majority of the project development. Due to site constraints including existing plant piping, steep slopes, and existing tree growth onsite, the bioretention cells will capture a total of 0.56 acres of runoff. As such, the bioretention cells have been evaluated to determine whether they will receiving and treating enough stormwater pollutant to reach the target removal of 0.16 lbs. The Albemarle County BMP worksheet was used to evaluate the drainage areas of all three bioretention cells. It was determined that BRC 1 receives 0.42 lbs of stormwater pollutant, BRC 2 receives 0.15 lbs of stormwater pollutant, and BRC 3 receives 0.16 lbs of stormwater pollutant, totaling 0.73 lbs of stormwater pollutant received by the bioretention cells. According to the Virginia Stormwater Management Handbook, First Edition, section 3.11 Bioretention, a bioretention cell sized to handle the 1"water quality volume will have a removal efficiency of 65%. The proposed bioretention cells at a pollutant efficiency of 65% will treat 0.47 lbs of the pollutant export received, exceeding the required removal of 0.16 lbs. Stormwater design analysis can be found in Appendix IV. Conclusion Project improvements as well as the proposed bioretention cells will reduce the overall peak flow and volume of stormwater draining from the property. A stormwater analysis of the project's receiving channels was evaluated to ensure adequacy based on the compliance of Minimum Standards 19 and 9VAC25-870-66. Calculations can be found in Appendices V and VI. Using the Albemarle County Simple Method Spreadsheet, it was determined that the site is required to reduce post-construction storm pollutant export by 0.16 lbs to meet the pre- construction loading rate. Three bioretention cells with 65% removal efficiencies are proposed, and will treat 0.47 lbs of stormwater pollutant. Calculations can be found in Appendix VI. Under these proposed conditions for the management/treatment of stormwater runoff, the Crozet WTP improvement is under compliance of all applicable performance standards and requirements CRITICAL SLOPES Critical slopes, as defined by the County of Albemarle, are areas of topographic inclines that exceed a 25% slope. By definition, if these slopes exist naturally, no disturbance or impact are to be made to these slopes without approval by the County. Critical slopes do exist on this site, however, the new development will not disturb or impact these slopes. Appendices Appendix I — Maps (FIRM, Vicinity, Soils) Appendix II — Contract Drawings (Under Separate Cover) Appendix III — Erosion Control Calculations Appendix IV—Stormwater Analysis Calculations Appendix V— MS-19 Calculations Appendix VI — Conveyance Calculations Appendix VII —Specifications Section 02050 — Demolition Section 02100 —Clearing, Grubbing, and Site Preparation Section 02200— Earthwork Section 02202 — Excavation by Blasting Section 02207—Aggregate Materials Section 02276 — Erosion and Sedimentation Control Section 02500 —Surface Restoration Section 02510 — Paving and Surfacing Section 02604— Utility Structures Section 02831 —Steel Fencing Section 02910 — Final Grading and Landscaping Appendix I Maps (FIRM, Vicinity, Soils) 1 > U W Y mW m W y 0.N to O �r oLL mm«gym 0 O. '� j a „`3L W HBO u °o gELi d y O ti 8" men al Q 7vo� O c u 5 =El 4, CV CV s 1— w ° .04 W w� a IIsZ S 3 g �a aniQr_ b o $� Q• W -I MI R"4. 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C v) 0u) 0 y O W A a m 7 N C R O Z n �I� Soil Map—Albemarle County,Virginia Crozet Water Treatment Plant Map Unit Legend Albemarle County,Virginia(VA003) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 36B Hayesville loam,2 to 7 percent 2.9 70.3% slopes 37C3 Hayesville clay loam,7 to 15 1.2 29.7% percent slopes,severely eroded Totals for Area of Interest 4.1 100.0% USDA Natural Resources Web Soil Survey 2/5/2014 41E11 Conservation Service National Cooperative Soil Survey Page 3 of 3 Appendix II Contract Drawings (Under Separate Cover) H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment Appendix Ill Erosion Control Calculations H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment Silt Fence Calculations H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment CROZET WTP GAC UPGRADES 5/7/2014 HAZENAND SAWYER EROSION CONTROL BY: BTE CHK. Environmental Engineers&Scientists SILT FENCE CALCULATIONS JOB NO.32135-002 Objective: Determine if silt fence will contain sediment generated. References: (1)Virginia Erosion and Sediment Control Handbook, Section 3.05. Procedure: As required by Reference 1, ensure that area drained by silt fence is no greater than ' acre per 100 feet of fencing. Fence Fence Area Number Length Drained OK? (ft) (ac) 1 OK 2 t:1., .P OK 3 r t tl ¢k OK 4i OK 5 � .. ti OK ‘44,00- Page 1 of 1 Appendix IV Stormwater Analysis H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment Albemarle County — Engineering Simple Method Spreadsheet Pre- and Post-construction H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment Short Version BMP Computations Albemarle County Water Protection Ordinance: Modified Simple Method Plan: GAC Upgrades for the Crozet WTP Water Resources Area: Drinking Water Watersheds Preparer: Hazen and Sawyer,P.C. Date: 14-May-14 Project Drainage Area Designation Crozet WTP upgrades L storm pollutant export in pounds, L=[P(Pj)Rv/12][C(A)2.72] Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 1 percent imperviousness P annual precipitation,43"in Albemarle A project area in acres in subject drainage area, A= 1.12 C pollutant concentration, mg/I or ppm target phosphorus f factor applied to RR V required treatment volume in cy,0.5"over imperv.area= A(I)43560(0.5/12)/27 RR required removal, L(post)-f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation(values in feet&square feet) Item pre-development Area post-development Area Roads Length Width subtotal Length Width subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3320 0 2291 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 271 *„,,, Parking Lots 1 2 3 4 1 2 3 4 0 0 0 0 Gravel areas Area Area 16602 x 0.70= 11621.4 12428 x 0.70= 8700 Structures Area no. subtotal Area no. subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 133 0 3228 Actively-grazed pasture& Area Area yards and cultivated turf 23505 x 0.08= 1880 25084 x 0.08= 2007 Active crop land Area Area x0.25= 0 x0.25= 0 Other Impervious Areas 0 0 Impervious Cover 35% 34% l(pre) l(post) Rv(post) V 0.35 25.5 New Development(For Development Areas,existing impervious cover<=20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 1.00 20% 0.36 2.49 2.44 -0.06 -2% Development Area 0.35 1.00 0% 0.36 1.25 1.22 -0.03 -2% Drinking Water Watersheds 0.40 1.00 1% 0.36 1.43 1.39 -0.03 -2% Other Rural Land *min.values Redevelopment(For Development Areas,existing impervious cover>20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 0.90 20% 0.36 2.49 2.44 0.19 8% Development Area ... 0.35 0.85 0% 0.36 1.25 1.22 0.16 13% Drinking Water Watersheds 0.40 0.85 1% 0.36 1.43 1.39 0.18 13% Other Rural Land Albemarle County — Engineering Simple Method Spreadsheets Drainage area to BRC 1, BRC 2, BRC 3 H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment Short Version BMP Computations Albemarle County Water Protection Ordinance: Modified Simple Method Plan: GAC Upgrades for the Crozet WTP Water Resources Area: Drinking Water Watersheds ..„,, Preparer: Hazen and Sawyer,P.C. Date: 14-May-14 Project Drainage Area Designation Drainage area to BRC 1 L storm pollutant export in pounds, L=[P(Pj)Rv/12][C(A)2.72] Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 I percent imperviousness P annual precipitation,43"in Albemarle A project area in acres in subject drainage area, A= 0.25 C pollutant concentration,mg/I or ppm target phosphorus f factor applied to RR V required treatment volume in cy,0.5"over imperv.area= A(I)43560(0.5/12)/27 RR required removal , L(post)-f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation(values in feet&square feet) Item pre-development Area post-development Area Roads Length Width subtotal Length Width subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 173 0 173 ,` Parking Lots 1 2 3 4 1 2 3 4 0 0 0 Gravel areas Area Area 4403 x 0.70= 3082.1 4403 x 0.70= 3082.1 Structures Area no. subtotal Area no. subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2472 0 2472 Actively-grazed pasture& Area Area yards and cultivated turf 3296 x 0.08= 263.68 x 0.08= 263.68 Active crop land Area Area x0.25= 0 x0.25= 0 Other Impervious Areas 0 0 Impervious Cover 55% 55% I(pre) ((post) Rv(post) V 0.55 9.2 New Development(For Development Areas,existing impervious cover<=20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 1.00 20% 0.55 0.84 0.84 0.00 0% Development Area 0.35 1.00 0% 0.55 0.42 0.42 0.00 0% Drinking Water Watersheds 0.40 1.00 1% 0.55 0.48 0.48 0.00 0% Other Rural Land *min.values Redevelopment(For Development Areas,existing impervious cover>20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 0.90 20% 0.55 0.84 0.84 0.08 10% Development Area 0.35 0.85 0% 0.55 0.42 0.42 0.06 15% Drinking Water Watersheds * 0.40 0.85 1% 0.55 0.48 0.48 0.07 15% Other Rural Land Short Version BMP Computations Albemarle County Water Protection Ordinance: Modified Simple Method Plan: GAC Upgrades for the Crozet WTP Water Resources Area: Drinking Water Watersheds .... Preparer: Hazen and Sawyer,P.C. Date: 14-May-14 Project Drainage Area Designation Drainage area to BRC 2 L storm pollutant export in pounds, L=[P(Pj)Rv/12][C(A)2.72] Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 I percent imperviousness P annual precipitation,43"in Albemarle A project area in acres in subject drainage area, A= 0.10 C pollutant concentration, mg/I or ppm target phosphorus f factor applied to RR ✓ required treatment volume in cy,0.5"over imperv.area= A(I)43560(0.5/12)/27 RR required removal , L(post)-f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation(values in feet&square feet) Item pre-development Area post-development Area Roads Length Width subtotal Length Width subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1941 0 1941 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 „ow, Parking Lots 1 2 3 4 1 2 3 4 0 0 0 Gravel areas Area Area 0 x 0.70= 0 0 x 0.70= 0 Structures Area no. subtotal Area no. subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Actively-grazed pasture& Area Area yards and cultivated turf 2597 x 0.08= 207.76 2597 x 0.08= 207.76 Active crop land Area Area x0.25= 0 x0.25= 0 Other Impervious Areas 0 0 Impervious Cover 49% 49% l(pre) l(post) Rv(post) V 0.49 3.3 New Development(For Development Areas,existing impervious cover<=20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 1.00 20% 0.49 0.30 0.30 0.00 0% Development Area 0.35 1.00 0% 0.49 0.15 0.15 0.00 0% Drinking Water Watersheds 0.40 1.00 1% 0.49 0.17 0.17 0.00 0% Other Rural Land *min.values Redevelopment(For Development Areas,existing impervious cover>20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 0.90 20% 0.49 0.30 0.30 0.03 10% Development Area .r. 0.35 0.85 0% 0.49 0.15 0.15 0.02 15% Drinking Water Watersheds * 0.40 0.85 1% 0.49 0.17 0.17 0.03 15% Other Rural Land Short Version BMP Computations Albemarle County Water Protection Ordinance: Modified Simple Method Plan: GAC Upgrades for the Crozet WTP Water Resources Area: Drinking Water Watersheds -41► Preparer: Hazen and Sawyer,P.C. Date: 14-May-14 Project Drainage Area Designation Drainage area to BRC 3 L storm pollutant export in pounds, L=[P(Pj)Rv/12][C(A)2.72] Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 I percent imperviousness P annual precipitation,43"in Albemarle A project area in acres in subject drainage area, A= 0.21 C pollutant concentration,mg/I or ppm target phosphorus f factor applied to RR ✓ required treatment volume in cy,0.5"over imperv.area= A(I)43560(0.5/12)/27 RR required removal , L(post)-f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation(values in feet&square feet) Item pre-development Area post-development Area Roads Length Width subtotal Length Width subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1384 0 1384 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r... Parking Lots 1 2 3 4 1 2 3 4 0 0 0 Gravel areas Area Area 0 x 0.70= 0 0 x 0.70= 0 Structures Area no. subtotal Area no. subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Actively-grazed pasture& Area Area yards and cultivated turf 7529 x 0.08= 602.32 7529 x 0.08= 602.32 Active crop land Area Area x0.25= 0 x0.25= 0 Other Impervious Areas 0 0 Impervious Cover 22% 22% I(pre) [(post) Rv(post) V 0.25 3.1 New Development(For Development Areas,existing impervious cover<=20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 1.00 20% 0.25 0.32 0.32 0.00 0% Development Area 0.35 1.00 0% 0.25 0.16 0.16 0.00 0% Drinking Water Watersheds 0.40 1.00 1% 0.25 0.18 0.18 0.00 0% Other Rural Land *min.values Redevelopment(For Development Areas,existing impervious cover>20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 0.90 20% 0.25 0.32 0.32 0.03 10% Development Area w- 0.35 0.85 0% 0.25 0.16 0.16 0.02 15% Drinking Water Watersheds * 0.40 0.85 1% 0.25 0.18 0.18 0.03 15% Other Rural Land Tc Calculation H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment U.S.Department of Agriculture FL-ENG-21 B Natural Resources Conservation Service 06/04 TR 55 Worksheet 3: Time of Concentration (Ta) or Travel Time (Tt) Project: Crozet Water Treatment Plant Designed By: Corinne Wilson, EIT Date: 4/15/14 Location: Crozet, VA Checked By: Date: Check one: Present I Developed Check one: 1 Tc Tt through subarea Bioretention Cell#1 NOTES: Space for as many as two segments per flow type can be used for each worksheet. Include a map, schematic, or description of flow segments. Sheet Flow(Applicable to T, only) Segment ID Grass/Sheet Pavement/Sheet 1. Surface description (Table 3-1) Grass Smooth 2. Manning's roughness coeff., n (Table 3-1) 0.24 0.01 3. Flow length, L (total L< 100 ft) ft 79 88 4. Two-year 24-hour rainfall, P2 in 3.7 3.7 5. Land slope, s ft/ft 0.035 0.034 6.Tt =0.007 (nL)°.8 Compute Tt hr 0.15 + 0.01 = 0.16 P20.5 s0.4 Shallow Concetrated Flow Segment ID Grass 7. Surface description (paved or unpaved) Unpaved 8. Flow length, L ft 1 62 -� 9. Watercourse slope, s ft/ft 0.645 10. Average velocity,V(Figure 3-1) ft/s 4.2 -- 11. Tt = L Compute It hr 0.00 + _■, = 0.00 3600 V Channel Flow Segment ID 12. Cross sectional flow area, a ft2 13. Wetted perimeter, Pw ft 14. Hydraulic radius, r= a Compute r ft Pw 15. Channel Slope, s ft/ft 16. Manning's Roughness Coeff., n 17. V= 1.49 r2i3 s112 Compute V ft/s n 18. Flow length, L ft 19. Tt = L Compute Tt hr + 3600 V 20. Watershed or subarea T,or Tt(add It in steps 6, 11, and 19 hr 0.16 U.S.Department of Agriculture FL-ENG-21 B Natural Resources Conservation Service 06/04 TR 55 Worksheet 3: Time of Concentration (Ta) or Travel Time (Tt) Project: Crozet Water Treatment Plant Designed By: Corinne Wilson, EIT Date: 4/15/14 Location: Crozet, VA Checked By: Date: Check one: Present I Developed Check one: I Tc Tt through subarea Bioretention Cell#2 NOTES: Space for as many as two segments per flow type can be used for each worksheet. Include a map, schematic, or description of flow segments. Sheet Flow(Applicable to Tc only) Segment ID Grass/Sheet 1. Surface description (Table 3-1) Grass 2. Manning's roughness coeff., n (Table 3-1) 0.24 -..I 3. Flow length, L (total L< 100 ft) ft 79 _" 4. Two-year 24-hour rainfall, P2 in 3.7 5. Land slope, s ft/ft 0.051 6. Tt =0.007 (nL)08 Compute Tt hr 0.13 + � ', = 0.13 P20.5 s0.4 Shallow Concetrated Flow Segment ID 7. Surface description (paved or unpaved) -- 8. Flow length, L ft 9. Watercourse slope, s ft/ft 10.Average velocity, V(Figure 3-1) ft/s -■' 11. Tt = L Compute Tt hr 0.00 + �,' = 0.00 3600 V Channel Flow Segment ID 12. Cross sectional flow area, a ft2 13. Wetted perimeter, Pte, ft 14. Hydraulic radius, r= a Compute r ft Pw 15. Channel Slope, s ft/ft 16. Manning's Roughness Coeff., n 17. V= 1.49 r2i3 s1/2 Compute V ft/s n 18. Flow length, L ft 19. Tt = L Compute Tt hr + _ 3600 V 20. Watershed or subarea or Tt(add Tt in steps 6, 11, and 19 hr 0.13 U.S.Department of Agriculture FL-ENG-2113 Natural Resources Conservation Service 06/04 TR 55 Worksheet 3: Time of Concentration (Ta) or Travel Time (Ti) Project: Crozet Water Treatment Plant Designed By: Corinne Wilson, EIT Date: 4/15/14 Location: Crozet,VA Checked By: Date: Check one: Present Developed Check one: I/ Tc Tt through subarea Bioretention Cell#3 NOTES: Space for as many as two segments per flow type can be used for each worksheet. Include a map, schematic, or description of flow segments. Sheet Flow(Applicable to Tc only) Segment ID Grass/Sheet 1. Surface description(Table 3-1) Grass 2. Manning's roughness coeff., n(Table 3-1) 0.24 3. Flow length, L(total L< 100 ft) ft 100 4. Two-year 24-hour rainfall, P2 in 3,7 5. Land slope, s ft/ft 0.065 6. It =0.007(nL)0.8 Compute Tt hr 0.14 + = 0.14 P2 0.5 50.4 Shallow Concetrated Flow Segment ID 7. Surface description (paved or unpaved) 8. Flow length, L ft 9. Watercourse slope, s ft/ft 10. Average velocity, V(Figure 3-1) ft/s 11.Tt = L Compute Tt hr 0.00 + = 0.00 3600 V Channel Flow Segment ID Channel 12. Cross sectional flow area, a ft2 0.4 13. Wetted perimeter, PW ft 6.2 14. Hydraulic radius, r= a Compute r ft 0.1 Pw 15. Channel Slope, s ft/ft 0.015 16. Manning's Roughness Coeff., n 0.03 17. V= 1.49 rya s112 Compute V ft/s 1.0 n 18. Flow length, L ft 27 19. Tt = L Compute It hr 0.01 + = 0.01 3600 V 20. 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I ) / / / /// i/ 7/, , Bioretention Cell Designs H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment HAZENANDSA 1 Environmental Engineers & Scientists Prepared by Hazen and Sawyer,P.C. Corinne Wilson, EIT Date of Calculation 2/4/2014 Client Albemarle County Project Name Crozet Water Tratment Plant Description Bioretention Cell#1 Design Reviewer L.Michael Santowasso, PE Date Reviewed Bioretention Cell #1 Design Table 1:Land Use Characteristics Land Use Area(ac) CN Rv Pervious 0.10 61 0.20 Impervious 0.15 98 0.95 Total 0.25 83 0.65 Table 2:Treatment Volume Calculation Precipitation depth,P in 1 1"water quality event Rvpost - 0.65 Treatment volume,Tv cf 590 (P)(Rv)(Area)/12 Table 3:Design Depth Calculation Layer Depth(ft) Void Ratio(Vr) Storage(ft) Gravel 1 0.4 0.4 Media 3 0.25 0.75 Ponding 0.5 1 0.5 Total(Design Depth) 1.65 Table 4:Surface Area Calculation Surface area,SA sf 447 (1.25*Tv)/(design depth) Length ft 30 Width ft 15 FI4ZENANDSAWER Environmental Engineers & Scientists Prepared by Hazen and Sawyer, P.C. Corinne Wilson,EIT Date of Calculation 2/4/2014 Client Albemarle County Project Name Crozet Water Tratment Plant Description Pretreatment Design for Bioretention Cell#1 Reviewer L. Michael Santowasso,PE Date Reviewed Pretreatment Cell Design Table 5:Peak Flow Calculation Drainage Area ac 0.02 C 0.95 Impervious in/hr 6.52 10-year,5-minute storm Peak Flow,Qp cfs 0.17 SCS Tr-20(HydroCAD) Table 6:Manning's Equation b ft/s 2 y ft 0.05 z 2 Rh ft/s 0.04 s 0.09 n 0.033 gravel, riprap NANNto, A sf 0.10 Qp cfs 0.17 equal to Qp,above V ft/s 1.71 maximum velocity of silt loam soil=2.3 ft/s Riprap Outlet Protection As a result of the low velocity,the minimum stone size(Class AI)is sufficient to avoid erosion of riprap ITAzENANDSAIWER Environmental Engineers & Scientists Prepared by Hazen and Sawyer,P.C. Corinne Wilson, EIT Date of Calculation 2/4/2014 Client Albemarle County Project Name Crozet Water Tratment Plant Description Bioretention Cell#2 Design Reviewer L. Michael Santowasso, PE Date Reviewed Bioretention Cell #2 Design Table 1:Land Use Characteristics Land Use Area(ac) CN Rv Pervious 0.06 61 0.20 Impervious 0.04 98 0.95 Total 0.10 77 0.52 Table 2:Treatment Volume Calculation Precipitation depth, P in 1 1"water quality event Rvpost - 0.52 Treatment volume,Tv cf 195 (P)(Rv)(Area)/12 Table 3:Design Depth Calculation Layer Depth (ft) Void Ratio(Vr) Storage(ft) Gravel 1 0.4 0.4 Media 3 0.25 0.75 Ponding 0.5 1 0.5 Total(Design Depth) 1.65 Table 4:Surface Area Calculation Surface area,SA sf 148 (1.25*Tv)/(design depth) Length ft 15 Width ft 10 IIAZENANDSAWER Environmental Engineers & Scientists Prepared by Hazen and Sawyer, P.C. Corinne Wilson, EIT Date of Calculation 2/4/2014 Client Albemarle County Project Name Crozet Water Tratment Plant Description Pretreatment Design for Bioretention Cell#2 Reviewer L. Michael Santowasso, PE Date Reviewed Pretreatment Cell Design Table 5:Peak Flow Calculation Drainage Area ac 0.04 C 0.95 Impervious in/hr 6.52 10-year,5-minute storm Peak Flow,Qp cfs 0.32 SCS Tr-20(HydroCAD) Table 6:Manning's Equation b ft/s 2 y ft 0.07 z 2 Rh ft/s 0.06 s 0.09 n 0.033 gravel,riprap A sf 0.15 Qp cfs 0.32 equal to Qp,above V ft/s 2.17 maximum velocity of silt loam soil=2.3 ft/s Riprap Outlet Protection As a result of the low velocity,the minimum stone size(Class Al)is sufficient to avoid erosion of riprap FLAZENANDSA Environmental Engineers Si Scientists Prepared by Hazen and Sawyer, P.C. Corinne Wilson, EIT Date of Calculation 5/13/2014 Client Albemarle County Project Name Crozet Water Tratment Plant Description Bioretention Cell#3 Design Reviewer L. Michael Santowasso, PE Date Reviewed Bioretention Cell #3 Design Table 1: Land Use Characteristics Land Use Area (ac) CN Rv Pervious 0.17 61 0.20 Impervious 0.03 98 0.95 Total 0.21 67 0.32 Table 2:Treatment Volume Calculation Precipitation depth, P in 1 1"water quality event Rvpost - 0.32 Treatment volume,Tv cf 236 (P)(Rv)(Area)/12 Table 3: Design Depth Calculation Layer Depth (ft) Void Ratio(Vr) Storage(ft) Gravel 1 0.4 0.4 Media 3 0.25 0.75 Ponding 0.5 1 0.5 Total(Design Depth) 1.65 Table 4:Surface Area Calculation Surface area,SA sf 179 (1.25*Tv)/(design depth) FIAZEN AND SAWYER Environmental Engineers & Scientists Prepared by Hazen and Sawyer, P.C. Corinne Wilson, EIT Date of Calculation 5/13/2014 Client Albemarle County Project Name Crozet Water Tratment Plant Description Pretreatment Design for Bioretention Cell#3 Reviewer L. Michael Santowasso, PE Date Reviewed Pretreatment Cell Design Table 5: Peak Flow Calculation Drainage Area ac 0.03 CN - 98 Impervious Peak Flow,Qp cfs 0.12 SCS Tr-20(HydroCAD) Table 6: Manning's Equation b ft/s 2 y ft 0.04 z 2 Rh ft/s 0.04 s 0.09 n 0.033 gravel, riprap A sf 0.08 Qp cfs 0.12 equal to Qp,above V ft/s 1.50 maximum velocity of silt loam soil=2.3 ft/s Riprap Outlet Protection As a result of the low velocity,the minimum stone size(Class Al)is sufficient to avoid erosion of riprap Appendix V MS-19 Calculations H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment Field Notes H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment I Y�7�� � � , ~rre a J Y'+` tl '"�,r17.' ,•r. :.,,. :, I traaN.n,,rr, , ,44„„,..----,,,, T ''."-,,.*,0,,,,-.'!'a «om . , ,, ars r � � off' (' """w "".•• s ". * ` 6J.1 Z ....4-,4Via,.. vJMSS`, : ' T- �U S �# M` 'r/ r ,.., 'fir " �,. �, A. 1' N j ,,' '1'''''1-17: , ', '. , ,, ., ., , ,, Y. f *. ;...str''..„' , if' , a Tar �+ a: ^'wry. �, i a .r t s. Picture 1 y ,a4 �.-° f e., !—j ; gilt •�.' ''� �. � �° .. "'. . P%.x}4' . - A ~ gn• i` ` .� zal.`' .k.- .i, r .: ` +a if .: i ,1 ,,,,.,,:., ,, ,., , „,,,,,, , / i,,, , , ',, '. . i , , k ,, /. I 7: km S......1,0r> ^•••• '$4c4 , / . , . . .y. \ ' .;I- ..'.,i., 1 :',,,,,......,,, ---; 'i., , :,),t,iit14 •400, i , . r.••••-: I ' .1%'4,,,,,,.,,kr.,4 iiii: - .,i-7, -,. .. F� .A.rte. E. 'jGA 'k g So ,1 Yom.. f �L .. it . f k a i.' .*la. v .i. 1• - d s a . .. 'Ati s € x� f V`� ` , ri ,g F , , 'g,'a �' Its Irk ,kale ` # ,. ,+a� t if';'‘i ,:14-"--,46,4;,,,.` � ', s z lir;4.4 "'/ i. r 9 git�.��A Q Jd 44 I `� vim,„+" ;,-.4 u:' 9a ! .. * /'�?`j R A-. 1 T ew .. y ; '' yy:F, \4 ' y M1 ,.* v Beginning of"channel"at fence line between site and adjacent residential property.Water tank in background. STA 0+00 Channel approximately 4'wide x 6"deep, parabolic cross section. kid Picture 2 . ,+. � ', . - .. P a ,: { w • b , a �. - 4 `� fi . x,� .� ,�,.. ,� ! * ?fi « 3 „:t .. ' + .»� i a .� { 4 µ • ms• .T'.. • ' 4 ya, . 4. r A .:. • - s , { � x �, a .. Vr _ ' • - ! f{ Y ' r by, _ . n y 1 �'7 r r ..:: i 4 r f� � O ♦� .� '‘ �. 44, i ;, y ,la i Vy_{. A Bend in "channel",approximately 30-degrees. STA 0+20 Channel approximately 4'wide x 3"deep, parabolic cross section. Picture 3 r ry. • IT • y h *t '44;.!-*; 14'...'1 * ' - '4* 4 , . , ., „ $ .. * .' •, Al 4. ._. #3 - �^r �. -..�.. �y ,' :'r* ': .:r., *, „' '74,.., iiiii . ` _ a t " t n. 4.? # % NyeX ' , r,�. •.- • + .: 44e t . r Actlik. . r _ ./ -j. 1: .". '' '` .•s • •, -� s nv til..s ; • . , - - yy $4,,,,, / � "Channel"at base of slope between properties.Off-site drainage contributing at this point. Beginning of bend. STA 0+50 Channel approximately 4'wide x 6"deep, parabolic cross section,small riprap(2"—4"stone) present in channel invert,approximately 2'wide. Picture 4 , i it l i . I. 1 9 ��" ' , 'ft k ;max I *.4•••,1'1,' —pr r .rom i r,iri u 4 s3 4111ka t , ' i. rt a , . , y 1r-4,4 * * L,'fia., , ` "Channel"at base of slope between properties.Additional off-site drainage contributing at this point. STA 1+00 Channel approximately 6'wide x 7"deep, parabolic cross section,small riprap(2"—4"stone) present in channel invert,approximately 2'wide. t y \ 1 d k 11 lik �j , '`a `" 4-, 4, "awe . '"1 ,"'k-.-7 - .T "w - ,gyp A , , . ,.,,, . . , rs , - . .. .y „. .., „,. � " ,, ,. _ " • , . Channel at base of slope between properties.Additional off-site drainage contributing at this point. Cross section becomes more defined between STA 1+00 and STA 1+50. STA 1+50 Channel approximately 7'wide x 12"deep,parabolic cross section,grass. rrr Niue ,,t.,.k,iv..,,,,,! . ., er,_4t , ,..,, ' . ...---.0'.'; ' '1'''' . --*.: a'ict r,? t ,� L. .:y,, ice... ,. ,,i1`•Sa k. twig M r£ F� w • .�+ cY 1* ,. . 'j t z> t x x z is Picture looking form STA 1+50 looking back to STA 1+00. Grass lined channel,with riprap bottom,sending approximately at STA 1+50. Picture 7 : 11 1)1 4. w*. 4 } . t A0 ' ../... • e:ri}, IPS.; •-.... . 4 f { ' I<w 4 - 9 k .: T t. Y h • ` y� ' a �p ,, I+ ,; •. Channel at base of slope between properties.Additional off-site drainage contributing at this point. Signs of bed erosion begin. STA 1+59 Channel approximately 7'wide x 12"deep, parabolic cross section,grass. 10 Picture 8 • 41. W • Channel at base of slope between properties. Additional off-site drainage contributing at this point. Bed erosion pronounced. STA 2+00 Channel approximately 7'wide x 12"deep, parabolic cross section,grass. Eroded channel invert approximately 1'wide, 8"deep, rectangular in section. 40, Picture 9 i'el...‘.40.21 I "*."7:.*7 li.1" '' .4, • d y„e / liivv..- 1,11 » - fit 4. , r • r ,.�. fir ' Apt �. . p r .Y` W X40 1'� ..� Vie' may$ Attik r. I .i. •� •- n.'. �'-'41-. Jai • Pr t *sfi '*' 6 4,, S r• - . r. d cf 74 1 ''t 7 .ry • ^ - :'- 'r. s & s-. 5 �•+, w ,jj�� • '1tA.rA i� .y, �, ...' if • 44,. . 1 t.0,4 4. . .1 414, ' . .,y .... • V :: ,,i• .. 41' .4 nA.. Yy + ridgy t4 ,Iftfat -4-°/-* a ' • • ��+ 3t :+Fly F $ . �' `r Channel at base of slope between properties.Additional off-site drainage contributing at this point. Bed erosion head cut more pronounced @ STA 2+25. STA 2+50(near base of tree,meets larger channel.) Channel approximately 8'wide x 15"deep,parabolic cross section,grass. leuroo Picture 10 7ter'' ' i 4�, ., ti, ' `, 1,-.0, . e = t44 ., ,, � X ; Wii' erd • .i" rter4 .i . •, v e 4 , 4So',,. slit, t . ; ..14�, . ' . t_ Le, i rwiY4 .. 't"--iI; I 1 l '' 1 '�.V L rf . ti *jm drY4. ' y} IIP'i J ,�„ .... • x * r ` j . w ,.- ter- y ± # v ` '"_. • - + " k' ` t, 4." "`. .qOlit � •'#GYM i, _� r,'L' • ":° ; tir `4'* t� y '-CW �' 'fir-�' x — ...:4::, .d Or .se "' e r — ' '. " + 5. y ,''a4 y .:fit `.v Yxiit r .. f ' 40 * 1R Picture downstream of larger channel,looking at end of MS-19 channel (near base of tree)and upstream to FES discharging flow for residential street/cul-de-sac. Picture 11 F + �r AVA'Y � ..:.:, , ..... : , ' , ti i� _ ,,,.., t• x _ „... - , .. .., , ; 4 , . .. _, ,.... ,....,- g. . . , _ ,. ,. ..,.,,,,,,t ., . . { 6t. . . ,.71Mti " .�i+ k. •vo .. ti ev", 4 n +,., � .,.,„ ,.•.iso^ x,.. .1 fr .. A . rt ' i I k E.: .. si ...nom'- _ .,ti ,o- 41, VS. .OW "*r w, ".. }� fid' :' l i' M ..3.r .. Y Picture of head cut at location where MS-19 stream joins flow from street FES.Approximately 18"deep. Peak Flow Calculations to Point of Analysis H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment U.S.Department of Agriculture FL-ENG-21 B Natural Resources Conservation Service 06/04 TR 55 Worksheet 3: Time of Concentration (Ta) or Travel Time (Tt) Project: Crozet Water Treatment Plant Designed By: Corinne Wilson, EIT Date: 4/15/14 Location: Crozet,VA Checked By: Date: Check one: Present r/ Developed Check one: 1 Tc Tt through subarea Point of Analysis NOTES: Space for as many as two segments per flow type can be used for each worksheet. Include a map, schematic, or description of flow segments. Sheet Flow(Applicable to Tc only) Segment ID Sheetflow 1 1. Surface description (Table 3-1) Grass 11111111111111111111 2. Manning's roughness coeff., n (Table 3-1) 0.24 3. Flow length, L (total L< 100 ft) ft 43 4. Two-year 24-hour rainfall, P2 in '.IIIIIIIIIM 5. Land slope, s ft/ft 0.035 IIIIIIIIIIIIII 6. Tt =0.007 jnU 0 8 Compute Ti hr 0.09 + ,IIIIIIIIII = 0.09 p20.5 S0.4 Shallow Concetrated Flow Segment ID Grass i Pavement 7. Surface description (paved or unpaved) Unpaved Smooth 8. Flow length, L ft 62 203 9. Watercourse slope, s ft/ft 0.645 0.037 10.Average velocity,V(Figure 3-1) ft/s 4.2 3.8 11. Tt = L Compute Tt hr 0.00 + , 0.01 = 0.02 3600 V Channel Flow Segment ID Channel 12. Cross sectional flow area, a ft2 22.5 13. Wetted perimeter, P, ft 11.3 14. Hydraulic radius, r= a Compute r ft 2.0 Pw 15. Channel Slope, s ft/ft 0.078 16. Manning's Roughness Coeff., n 0.04 17. V= 1.49 r2/ 3 S112 Compute V ft/s 18.9 n 18. Flow length, L ft 408 19. Tt = L Compute Tt hr 0.01 + = 0.01 3600 V 20. Watershed or subarea T,or Tt(add Tt in steps 6, 11, and 19 hr 0.12 ri- kV' b**0001 20140416 3:19P O:\32135—RAL\32135--002\drowings\000 SITE\Crozet\Stormwater & E&S\MS19DrainageAreas.,dwg By:CDWILSON Last Saved By: cdwilson Z> 07 / . 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Corinne Wilson, EIT Date of Calculation 4/29/2014 Client RWSA Project Name Crozet WTP GAC updates Description Rational method calculations to point of analysis Reviewer Mike Santowasso,PE Date Reviewed Table 1:Drainage Area Calculations C Predevelopment(ac) Postdevelopment(ac) Impervious 0.95 1.20 1.15 Grassed 0.25 1.45 1.50 Wooded 0.15 1.02 1.02 Total 3.67 3.67 Table 2:Rational Method Calculations Predevelopment Postdevelopment Composite C 0.45 0.44 2-yr Intensity(i) in/hr 4.75 4.75 10-yr Intensity(i) in/hr 6.30 6.30 2-yr Peak Flow(Q ) cfs 7.87 7.70 10-yr Peak Flow(Q ) cfs 10.43 10.21 Change in Op -2% ``mow' HydroCAD Analysis of 2-Year Storm Velocity H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment 1992 3.17 TABLE 3.17-A PERMISSIBLE VELOCITIES FOR GRASS-LINED CHANNELS CHANNEL LINING PERMISSIBLE SLOPE VELOCITY' Bermudagrass 6 ft./second Reed canarygrass 0 - 5% Tall fescue , 5 ft./second Kentucky bluegrass Grass-legume mixture 4 ft./second Red fescue Redtop Sericea lespedeza 2.5 ft./second Annual lespedeza Small grains (temporary) Bermudagrass 5 ft./second 5 - 10% Reed canarygrass Tall fescue 4 ft./second Kentucky bluegrass Grass-legume mixture 3 ft./second Bermudagrass 4 ft./second Greater than 10% Reed canarygrass Tall fescue 3 ft./second Kentucky bluegrass For highly erodible soils, permissible velocities should be decreased by 25%. An erodibility factor (K) greater than 0.35 would indicate a highly erodible soil. Erodibility factors (K-factors) for many Virginia soils are listed in Chapter 6. Source: Soil and Water Conservation Engineering, Schwab, et.al. III - 135 HydroCAD Report: Hydrographs from the 2-Year Storm at each Cross Section. Maximum velocities tabulated below: Cross Section Maximum Velocity(ft/s) 0+00 4.78 0+20 3.71 0+50 4.79 1+00 4.42 1+50 4.57 2+00 5.75 2+50 5.50 0+00 Hydfogtaph 7 80 es —Inflow a -Outflow inflow Atea=3 6.70 ac 7 Avg ROW Depth.°58' 6 1.4ax Vel--4,18 fps ts 5 n=0 035 L.20 0' 4 I S=0 0500 -" 0 Capac 44=5.93 Ors u. 3 0 5 6 7 89 10 11 12 13 14 15 16 17 18 19 20 Time (hours) 0+20 Hydrogtaph 7 81 cfs —Inflow —Outflow Inflow Area.-=3 784 ac Avg Flow eepth=0 61' 6 Max Vel=3./1 fps 5 n..0 036 1.30 0' 4 SQ 0500 0 Capacarl 90 es 2 0 5 6 7 S 9 10 .11 12 13 14 15 16 17 18 19 20 Time (hours) ritimpoe 0+50 Hydrograph --------- 1=1 —inflow —Outflow inflow Area.-3 794 ac 7 Avg Flow Del:411=0 58' Max Vet=4 i9 firs = 035 4 S00510 Capactty=5 93 445 111. 3 2 1 5 6 7 a 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) 1+00 Hydra raph - 781 cfs —Inflow —Outflow isof04.,Area=3 373 44 7 Avg Flow CMpth4 E Max Vet.4.4124s 5 .nzi0 035 U5017' 4 S---0 0500 0 CapacAy=11 50 Os Now' ri: 2 1 a 5 6 7 & 9 10 11 12 13 14 15 16 17 13 19 20 Time (hours) 1+50 Hydrograpti 7.83 c.s —inflow —Outflow Inflow Area=4 092 ac 7 Avg Flow Depth.°52 ??. Max Velma-tit s nal 035 L=507 4 8=0 0500 2 capac,ty=32$9 as S 6 7 a 9 10 11 12 la 14 15 16 17 18 19 20 Time (hours) 2+00 Hydrograph 12 11 42 cis —Inflow —Outflow inflow Area=6.%22 ac 10 Avg.Prow Depth,-0,75' 8 Max Vel=5.76 fps L=58.0` S=0.0500 6 Capacity=23.32 cfs 4 5 6 7 S 9 1011 12 1314 15 16 1718 1920 Time (hours) 2+50 Hydrograph 16 14.84 cfs I -- • —Inflow T ?9 inthre.Ar cr=7 990 —Outflow �2 Avg flow Depth 69' Max Vel=5 50 fps n=0 035 L=50 0' S=O o500`,- Nur IL 6 Capacity=53 85 cls 4 a 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) �r� HEC-RAS Analysis of 10-Year Channel Capacity H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment HEC-RAS Analysis of 10-Year Channel Capacity "" H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment 4440.- Station 0+00 .035 ›r* .035 )-4- .035 Legend 1 t. WS 10-Yr 614.8- WS 2-Yr Ground a 614.6-1 Bank Sta 614.4 614.2- 614,0 ti 613.8 613 6 1 613.4 0 2 4 6 8 10 Station(ft) Station 0+20 .035 .035 )1*-- --.035----................ , j Legend WS 10-Yr 613.6 WS 2-Yr Ground • 613.4 1 Bank Sta 613.2 I 1 w 613 0 612.8 612.6-4 1 612.4 t • 0 2 4 6 8 10 Station(ft) Now- Station 0+50 iF 035- 033 --- 035— _., _Legend 612.4 WS 10-Yr !J I WS 2-Yr i E Ground 612.2 • Bank Sta i 612.0' ° 611 8 • m 6116 -- 611.4- ! 611.2-! 611.0- T___r_—r.___,_ _ 0 2 4 6 8 10 Station(ft) Station 1+00 4- .035 , - .033 --- -r:e-- --.035 ----- 3.1 - Legend J 610.0- WS 10-Yr r j / I WS 2-Yr ■ 809 8- Ground • Bank Sta 609-6 r 609.4 c i 0 w 609 2 609.0 608.81 608.6 ) 608 4+ 0 2 4 6 8 10 12 Station(ft) Station 1+50 ft — ono- 035 - 035 on«�+ � —^--| WS 10-Yr mme,, 608 ° Ground | \ • Bank 607 607 0 606 5 606- v 2 4 6 8 10 12 14 Station(ft) Station 2+00 _ 035__ �_----�oxs —� ---.035 606 Legend WS 10-Yr WS 2-Yr 605.5. / Ground • ~~~Sta _.~1 605 0 0 � � aws- 60m mun^'--- —'� ' --_— 0 2 4 6 8 10 12 14 Station 2+50 K ._ _ 035 - 035 604.0 –.035— r Legend WS 10-Yr 603.5 WS 2-Yr i Ground Bank Sta L. 603.0- c 602.5- > m w 602.0 .-- / j, — ---- 6015I j 601 0 f - r --- - 0 2 4 6 8 10 12 14 Station(ft) Appendix VI Conveyance Calculations H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment Channel Adequacy Calculations H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment HAzENANU Environmental Engineers & Scientists Prepared by Bret Edwards, PE Date of Calculation 5/14/2014 Client RWSA Project Name Crozet WTP GAC updates Description Channel Analysis Reviewer Mike Santowasso, PE Date Reviewed Table 1:Drainage Area Calculations CN Predeveloped(ac) Developed(ac) Impervious 98 1.20 1.15 Grassed 61 1.45 1.50 Wooded 55 1.02 1.02 Total 3.67 3.67 Table 2: Pre and Post Volume units Predeveloped Developed Developed(with Treatment) 1-yr(24hr)precipitation(P) in 3.04 3.04 3.04 Composite CN a 71.4 70.9 69.50 Storage capacity(S) 4.00 4.10 4.39 Runoff Depth in 0.80 0.78 0.714 Drainage Area sf 160,011 160,011 160,011 RV(Runoff Volume) cf 10,723 10,401 9,517 N4000-- a Composite CN value for"postdevelopment with treatment"obtained from Virginia RRM Spreadsheet,Channel and Flood Protection tab Table 2: Peak Flow(1 yr-24 hr) units Predeveloped Developed Developed(with Treatment) 1-yr(24hr) Peak Flow(Qp)b cfs 4.15 4.03 3.73 b Peak Flow values obtained from SCS Graphical Peak Discharge Spreadsheet Table 4:QDeveloped 5 l•F*(Qpre-Developed*RVpre-Developed)/RVDeveloped I.F. (site>1 acre): 0.8 QDeveloped• 3.73 RVDeveloped: 9,517 QPre-Developed 4.15 RVpre-Developed• 10,723 I•F*(QPre-Developed*RVpre-Developed)/RVDeveloped 3.74 Virginia Runoff Reduction Method Worksheet H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment 1-year storm 2-year storm 10-year storm Target Rainfall Event(in) Drainage Area { - - __ ' Drainage Area(acres) 3 67 Runoff Reduction Volume(cf) 849 • Drainage Area B Drainage Area(acres) 0.00 Runoff Reduction Volume(cf) 0 i Drainage Area C --1--- Drainage r-Drainage Area(acres) 0.00 Runoff Reduction Volume(cf) 0 _ t Drainage Area D Drainage Area(acres) 0.00 rh Runoff Reduction Volume(cf) 0 Drainage Area E Drainage Area(acres) 0.00 _ - Runoff Reduction Volume(cf) C Based on the use of Runoff Reduction practices in the various drainage areas,the spreadsheet calculates an adjusted Vdeveloped and adjusted Curve Numbe,. Drainage Area A A soils B Soils C Soils D Soils Forest/Open Space--undisturbed,protected forest/open Area(acres) 0.0 1.0 0.0 0.0 space or reforested land ON 30 55 70 77 Managed Turf-disturbed,graded for yards or other turf to be Area(acres) 0.0 1.5 0.0 0.0 mowed/managed _-_ CN 39 61 74 80 Area acres) 0.0 1.2 0.0 0.0 _ Impervious Cover CN 98 98 98 98 Weighted CN S - _ t_ 70.93 I 4.10 1-year storm 2-year storm 10-year storm -.RVo,,,i,P,d(in)with no Runoff Reduction 0.78 0.97 2.22 RVo,,,,,,,,(in)with Runoff Reduction 0.72 0.90 2.16 Adjusted CN 69.5 70 70 Drainage Area B A soils B Soils IC Soils D Soils Forest/Open Space-undisturbed,protected forest/open Area(acres) 0 0 0.0 0.0 0.0 44 space or reforested land CN 30 55 70 77 Managed Turf-disturbed,graded for yards or other turf to be Area(acres) 0.0 0.0 0 0 0.0 mowed/managed N 39 61 74 80 Impervious Cover Area(acres) 0.0 0.0 0.0 0.0 N 98 98 98 98 j Weighted CN S I � 0 1 1000.00 1 1-year storm 2-year storm 10-year storm RVo,„,,,,,,(in)with no Runoff Reduction 0.00 000 0.00 RV0,,,,10r„d(in)with Runoff Reduction 0.00 0.00 0.00 • I Adjusted CN #NIA #NIA #NIA Drainage Area C A soils B Soils C Soils D Soils Forest/Open Space-undisturbed,protected forest/open Area(acres) 0.0 0.0 0.0 0.0 space or reforested land CN 30 55 70 77 Managed Turf-disturbed,graded for yards or other turf to be Area(acres) 0.0 " 0.0 0.0 0.0 _--_ mowed/managed CN 39 61 74 80 Area(acres) 0.0 0.0 0.0 0.0 Impervious Cover CN 98 98 98 98 _ _ Weighted CN S ] 0 I 1000.00 y__ _ 1-year storm 2-year storm 10-year storm RVo,,,_(in)with no Runoff Reduction 0.00 0.00 0.00 11 _ _RV5,,,,,,,a(in)with Runoff Reduction 0.00 0.00 0.00 T Adjusted CN #NIA #N/A #N/A __ Drainage Area D A soils B Soils 'C Soils D Soils Forest/Open Space--undisturbed,protected forest/open Area(acres) 0.0 0.0 0.0 0.0 space or reforested land CN 30 55 70 77 Managed Turf-disturbed,graded for yards or other turf to be Area(acres) 0.0 0.0 0.0 0.0 mowed/managed CN 39 61 74 80 Area(acres) 00 0.0 0.0 0.0 Impervious Cover CN 98 98 98 98 -- ---. - ---_-_.-.. Wei hted CN S 0 j 1000.00 _--_ I_- 1-year storm 2-year storm 10-year storm RVo,,,,i,p.,(in)with no Runoff Reduction 0.00 0.00 0.00 RVo,,,i,,,,,(in)with Runoff Reduction 0.00 000 0.00 Adjusted CN #N/A #WA MIA Drainage Area E A soils B Soils C Soils D Soils Forest/Open Space--undisturbed,protected forest/open Area(acres) 0.0 0.0 0.0 - 0.0 to `- space or reforested land CN 30 55 70 77 Managed Turf--disturbed,graded for yards or other turf to be Area(acres) 0.0 0 0 0.0 0.0 mowed/managed CN 39 61 _ 74 80 Area(acres) 0.0 0.0 0.0 0.0 _ _______ Impervious Cover N 98 98 98 98 Weighted CN S 0 I 1000.00 1-year storm 2-year storm 10-year storm RVpo..loped(in)with no Runoff Reduction 0.00 0.00 0.00 RVoovoiopou(in)with Runoff Reduction 0.00 0.00 0.00 Adjusted CN #NIA #N/A #NIA ------..: • Using the Adjusted Curve Number for each drainage area,calculate peak discharges for the 1,2,and 10 year storm. Compare the peak discharges to the allowable discharge rates described in the Virginia Stormwater Management Program Permit Regulations(4VAC 50-60-66(A),conditions 1-5 and 4VAC 50-60-66(B),conditions 1-5). SCS Peak Discharge H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment Predeveloped Page 1 Predeveloped Site SCS METHOD 0-2000 Acres Method can be used for estimating peak flows from urban areas X 1-yr 24 hr storm ter Project Crozet WTP Date 5/14/14 Name BTE Check LMS 1. Runoff Curve Number Hydrologic Cover description CN Area Product of Soil Group (table 2-2a-c) CN x area B Impervious 98 1 2 117.6 B Open Space(fair condition, 50%to 75%) 61 1 5 88.45 B Wooded(good condition) 55 1 0 56.1 0 Totals 3 / 262.15 Weighted CN 71.43 2. Runoff Storm#1 Frequency yr Rainfall, P(24-hr) (RD) in 3.04' Runoff,Q in 0.804 Q=(P-0.2 S)2 / (P+0.8S) S=(1000/CN)-10 4.00 loompr `fir SCSpeakdischarge 5/14/2014 Predeveloped Page 2 3.Time of Concentration(Tc)or travel time(Tt) Space for as many as two segments per flow type can be used for each worksheet Include a map,schematic,or description of flow segments low(applicable to Tc only) segment 1 1. Surface description(Table 3-1) Lo 1 Development Mod Develop re-t 2.Manning's roughness coefficient,n(Table 3-1) 0.210 3. Flow length L(not greater than 300ft) ft 4.One-year 24-hour rainfall P1 in 3 041 5. Land Slope,s ft/ft 0.04! 6. Tt= 0.007(nL) 8 computed Tt hr C 101 ' 101 p20.5 s0.4 Shallow concentrated flow segment 1 2 7. Surface description(paved or unpaved) bow Development Mod Development 8. Flow length, L ft 62 203 9. Watercourse slope,s ft/ft _ 0.6450 0.037 10.Average velocity,V(Figure 3-1) fUs 4 2 3 5 11. Tt=L/(3600`V) computed Tt hr 0.00 0 01 0 02 Channel flow segment 1 2 12.Cross sectional flow area,a ft2 22 5 Assumption: 1ft depth(n 13. Wetted Perimeter,pw ft 11 3 14. Hydraulic radius,r=a/pH, ft 2.0 15. Channel slope,s ft/ft 0.078 16. Manning's roughness coefficient,n(Table 2-3) 0 C4 17,V=1.49(r2/3s1/2) /n ft/s 16.5 'Noaar,.w length, L ft 408T 19.Tt= L/(3600*V) hr 0.0071 0.007 20. Watershed or subarea Tt(add Tt in steps 6, 11, 19) 0.125 hours 4. Graphical Peak Discharge Method 1. Data Drainage area A, 0.01 mi2(acres/640) Runoff curve number CN 71.43 (from step 1) Time of concentration Tt 0.13 hr (from step 3) Rainfall distribution 11 (l,la, II, III) Pond and swamp areas spread _ 11 Assumption:min of 0%swamp area throughout watershe(table 4-2) Storm 2. Frequency 1 3.Rainfall, P(24-hr) 3.04 4.Initial abstraction,la 0 8117 (Use CN with table 4-1) 5.Compute la/P 0.26875 6.Unit peak discharge,q„ 900 (Use Tt and la/P with exhibit 4- II 7. Runoff,Q 0.804 (r step 2) id and Swamp adjustment factor,Fp 1 90 ak discharge,qp 4.15 cfs 1863.26 gpm q8=q„Am 0 Fp SCSpeakdischarge 5/14/2014 Developed Page 1 Developed Site SCS METHOD 0-2000 Acres Method can be used for estimating peak flows from urban areas X 1-yr 24 hr storm Project Crozet 4VTP Date 5/14/14 Name BTE Check MS 1. Runoff Curve Number Hydrologic Cover description CN !Area Product of Soil Groff (table 2-2a-c) CN x area B lmperooJs 98 1.2 112.7 B Open Space(good condition.grass cover>75?-0) 61 1.5 91.5 B Wooded(good condition) 55 1 0 56.1 0 Totals 3.7 260.3 Weighted CN 70.93 2. Runoff Storm#1 Frequency yr 1 Rainfall,P(24-hr) (RD) in 3.041 Runoff,Q in 0.780 Q=(P-0.2S)2 / (P+0.8S) S=(1000/CN)-10 410 Noisiv SCSpeakdischarge 5/14/2014 Developed Page 2 3.Time of Concentration(Tc)or travel time(Tt) Space for as many as two segments per flow type can be used for each worksheet Include a map,schematic,or description of flow segments eet Flow(applicable to Tc only) `ter segment 1 2 1. Surface description(Table 3-1) Love Deyel©pmen:JMod Developmeni 2.Manning's roughness coefficient,n(Table 3-1) 0 2=6; 3.Flow length L(not greater than 300ft) ft 4.One-year 24-hour rainfall P1 in 5. Land Slope,s ft/ft 6. Tt= 0.007(nL 1°.8 computed Tt hr 0.10 __ 0.10 P20.5 so.a Shallow concentrated flow segment 1 2 7. Surface description(paved or unpaved) Low Develocment'Mod Development 8.Flow length,L ft 62 203 9. Watercourse slope,s ft/ft - 0 6450, 0.037 10.Average velocity,V(Figure 3-1) ft/s 4.2 3.8. 11. Tt=L/(3600*V) computed Tt hr 0.001 0.011 0.02 Channel flow segment 1 2 12.Cross sectional flow area,a ft2 22.5 Assumption: 1ft depth(normal) 13. Wetted Perimeter,pw ft i 3 14. Hydraulic radius,r=a/pw ft 2.0 15. Channel slope,s ft/ft 0 07 16. Manning's roughness coefficient,n(Table 2-3) 0 04 17,V=1.49(r2/3 s 112) /n ft/s 16.5 18.Flow length,L ft r 4081 Num.,4.Tt= L/(3600*V) hr 0.007 I 0.007 20. Watershed or subarea Tt(add Tt in steps 6, 11, 19) 0.125 hours 4. Graphical Peak Discharge Method 1. Data Drainage area A,, 0.01 mit(acres/640) Runoff curve number CN 70.93 (from step 1) Time of concentration Tt 0.13 hr (from step 3) Rainfall distribution (I,la,II,Ill) Pond and swamp areas spread Assumption:min of 5%swamp area throughout watershe(table 4-2) Storm#1 2. Frequency 1 3.Rainfall,P(24-hr) 3.04 4.Initial abstraction,la (Use CN with table 4-1) 5.Compute la/P 0.2819079 6.Unit peak discharge,q„ Lu ) (Use Tt and la/P with exhibit 4- II 7. Runoff,Q 0.780 (From step 2) 8. Pond and Swamp adjustment factor,Fp 1 9 Peak discharge,qp 4.03 cfs 1807.25 gpm =q„A,,,QFp SCSpeakdischarge 5/14/2014 Developed(Treated) Page 1 Developed Site(Treated) SCS METHOD 0-2000 Acres Method can be used for estimating peak flows from urban areas X 1-yr 24 hr storm Project Crozet WTP Date 5/14/14 Name BTE Check LMS 1. Runoff Curve Number Weighted CN 69.70 2. Runoff Storm#1 Frequency yr Rainfall,P(24-hr) (RD) in 3 041 Runoff,Q in 0.723 Q=(P-0.2S)2 / (P+0.8S) S=(1000/CN)-10 -1 35 Some Some SCSpeakdischarge 5/14/2014 Developed(Treated) Page 2 3.Time of Concentration(Tc)or travel time(Tt) Space for as many as two segments per flow type can be used for each worksheet Include a map,schematic,or description of flow segments eet Flow(applicable to Tc only) Nor, segment 1 2 1. Surface description(Table 3-1) o«, Deveiopm e'i Mod Develop-len' 2.Manning's roughness coefficient,n(Table 3-1) - 0 240 3.Flow length L(not greater than 300ft) ft 4.One-year 24-hour rainfall P1 in 5. Land Slope,s ft/ft 0 04 6. Tt= 0.007(nL)°8 computed Tt hr 0.10 0.10 P20.5s°a Shallow concentrated flow segment 7. Surface description(paved or unpaved) Lov De'.esop en: Mod De✓eiopm' 8.Flow length,L ft 62 9. Watercourse slope,s ft/ft 3.6456 0 637 10.Average velocity,V(Figure 3-1) ft/s 2 11. Tt=L/(3600*V) computed Tt hr 0.001 0.011 0.02 Channel flow segment 12.Cross sectional flow area,a ft2 Assumption: 1ft depth(normal) 13. Wetted Perimeter,pw ft 14. Hydraulic radius,r=a/pw ft 2 0 15. Channel slope,s ft/ft 0.078 16. Manning's roughness coefficient,n(Table 2-3) 0.00 - -- 17,V=1.49(r 2/3 1/2 s ) /n ft/s 166 18.Flow length,L ft )8i 3.Tt= L/(3600*V) hr 0.0071 0.007 20. Watershed or subarea Tt(add Tt in steps 6, 11,19) 0.125 hours 4. Graphical Peak Discharge Method 1. Data Drainage area Am 0.0057344 mit(acres/640) Runoff curve number CN 69.7 (from step 1) Time of concentration Tt 0.1251293 hr (from step 3) Rainfall distribution (I, la,II, Ill) Pond and swamp areas spread Assumption:min of 5%swamp area throughout watershe(table 4-2) Storm#1 2. Frequency 1 3.Rainfall,P(24-hr) 3.04 4.Initial abstraction,I, (Use CN with table 4-1) 5.Compute la/P 0.2894737 6.Unit peak discharge,q„ (Use Tt and la/P with exhibit 4- II 7. Runoff,Q 0.723 (From step 2) 8. Pond and Swamp adjustment factor,Fp 1 9 Peak discharge,qp 3.73 cfs 1674.77 gpm q,A,QF, SCSpeakdischarge 5/14/2014 Appendix VII Specifications H&S Project No.32135-002 Crozet Water Treatment Plan Site Plan Amendment SECTION 02050 DEMOLITION PART 1 -- GENERAL 1.01 THE REQUIREMENT A. The Contractor shall furnish all labor, materials and equipment in accordance with the requirements of Section 01520-Maintenance of Utility Operations during Construction and Section 01540 - Demolition and Removal of Existing Structures and Equipment. B. In addition, the Contractor shall demolish and remove all concrete and asphaltic paving, curbs, sidewalk, and miscellaneous yard structures as required and shown on the Contract Drawings during the construction work. 1.02 RELATED WORK SPECIFIED ELSEWHERE A. Section 01090 - Reference Standards B. Section 01520 - Maintenance of Utility Operations during Construction C. Section 01540 - Demolition and Removal of Existing Structures and Equipment 1.03 REFERENCE SPECIFICATIONS, CODES, AND STANDARDS A. References shall be in accordance with reference standards, codes, and specifications as set forth herein and in Section 02100 - Clearing, Grubbing, and Site Preparation. PART 2 -- EXECUTION 2.01 DEMOLITION A. Existing concrete and asphaltic paving, curbs, sidewalk and miscellaneous yard structures within the areas designated for new construction work shall be completely demolished and all debris removed from the site. B. Excavation caused by demolition shall be backfilled with fill free from rubbish and debris. C. Work shall be performed in such manner as not to endanger the safety of the workmen or the public or cause damage to nearby structures. D. Provide all barriers and precautionary measures in accordance with Owner's requirements W and other authorities having jurisdiction. E. Where parts of existing structures are to remain in service, demolish the portions to be removed, repair damage, and leave the structure in proper condition for the intended use. Remove concrete and masonry to the lines designated by drilling,chipping,or other suitable 32135-002102050:5/7/2014 02050-1 GAC Upgrades for the Crozet and Scottsville WTPs methods. Leave the resulting surfaces reasonably true and even, with sharp straight corners that will result in neat joints with new construction and be satisfactory for the purpose intended. Where existing reinforcing rods are to extend into new construction, remove the concrete so that the reinforcing is clean and undamaged. Cut off other reinforcing 1/2-inch below the surface and fill with epoxy resin binder flush with the surface. F. Prior to the execution of the work, the Contractor, Owner and Engineer shall jointly survey the condition of the adjoining and/or nearby structures. Photographs and records shall be made of any prior settlement or cracking of structures, pavements, and the like, that may become the subject of possible damage claims. 2.02 DISPOSAL OF MATERIAL A. All debris resulting from the demolition and removal work shall be disposed of by the Contractor as part of the work of this Contract. Material designated by the Engineer to be salvaged shall be stored on the construction site as directed. All other material shall be disposed of off site by the Contractor at his expense. B. Burning of any debris resulting from the demolition will not be permitted at the site. - END OF SECTION - 32135-002102050:5/7/2014 02050-2 GAC Upgrades for the Crozet and Scottsville WTPs SECTION 02100 CLEARING, GRUBBING, AND SITE PREPARATION PART 1 -- GENERAL 1.01 THE REQUIREMENT A. Includes all labor, material, equipment and appliances required for the complete execution of any additions, modifications, or alterations to existing building(s)and new construction work as shown on the Drawings and specified herein. B. Principal items of work include: 1. Notifying all authorities owning utility lines running to or on the property. Protecting and maintaining all utility lines to remain and capping those that are not required in accordance with instructions of the Utility Companies,and all other authorities having jurisdiction. 2. Clearing the site within the Contract Limit Lines, including removal of grass, brush, shrubs, trees, loose debris and other encumbrances except for trees marked to remain. 3. Boxing and protecting all trees, shrubs, lawns and the like within areas to be preserved. Relocating trees and shrubs, so indicated on the Drawings, to designated areas. 4. Repairing all injury to trees, shrubs, and other plants caused by site preparation operations shall be repaired immediately. Work shall be done by qualified personnel in accordance with standard horticultural practice and as approved by the Engineer. 5. Removing topsoil to its full depth from designated areas and stockpiling on site where directed by the Engineer for future use. 6. Disposing from the site all debris resulting from work under this Section. 1.02 RELATED WORK SPECIFIED ELSEWHERE A. Section 02200 - Earthwork 1.03 REFERENCE SPECIFICATIONS, CODES, AND STANDARDS A. Virginia Administrative Code, Title 9 N 1.04 STREET AND ROAD BLOCKAGE A. Closing of streets and roads during progress of the work shall be in compliance with the requirements of the Owner and other authorities having jurisdiction. Access shall be provided to all facilities remaining in operation. 32135-002102100:5/7/2014 02100-1 GAC Upgrades for the Crozet and Scottsville WTPs 1.05 PROTECTION OF PERSONS AND PROPERTY A. All work shall be performed in such a manner to protect all personnel,workmen, pedestrians and adjacent property and structures from possible injury and damage. B. All conduits, wires, cables and appurtenances above or below ground shall be protected from damage. C. Provide warning and barrier fence where shown on the Drawings and as specified herein. PART 2 -- EXECUTION 2.01 CLEARING OF SITE A. Before removal of topsoil, and start of excavation and grading operations, the areas within the clearing limits shall be cleared and grubbed. B. Clearing shall consist of cutting, removal,and satisfactory disposal of all trees,fallen timber, brush, bushes, rubbish, sanitary landfill material, fencing, and other perishable and objectionable material within the areas to be excavated or other designated areas. Prior to the start of construction, the Contractor shall survey the entire Contract site and shall prepare a plan which defines the areas to be cleared and grubbed, trees to be pruned, extent of tree pruning,and/or areas which are to be cleared but not grubbed. This plan shall be submitted to the Engineer for approval. Should it become necessary to remove a tree, bush, brush or other plants adjacent to the area to be excavated, the Contractor shall do so only after permission has been granted by the Engineer. C. Excavation resulting from the removal of trees, roots and the like shall be filled with suitable material, as approved by the Engineer, and thoroughly compacted per the requirements contained in Section 02200, Earthwork. D. Unless otherwise shown or specified, the Contractor shall clear and grub a strip at least 15 ft. wide along all permanent fence lines installed under this Contract. E. In temporary construction easement locations,only those trees and shrubs shall be removed which are in actual interference with excavation or grading work under this Contract, and removal shall be subject to approval by the Engineer. However, the Engineer reserves the right to order additional trees and shrubs removed at no additional cost to the Owner, if such, in his opinion, are too close to the work to be maintained or have become damaged due to the Contractor's operations. 2.02 STRIPPING AND STOCKPILING EXISTING TOPSOIL A. Existing topsoil and sod on the site within areas designated on the Drawings shall be stripped to whatever depth it may occur, and stored in locations directed by the Engineer. B. The topsoil shall be free of stones, roots, brush, rubbish,or other unsuitable materials before stockpiling the topsoil. 32135-002102100:5/7/2014 02100-2 GAC Upgrades for the Crozet and Scottsville WTPs C. Care shall be taken not to contaminate the stockpiled topsoil with any unsuitable materials. 2.03 GRUBBING A. Grubbing shall consist of the removal and disposal of all stumps, roots, logs,sticks and other perishable materials to a depth of at least 6-inches below ground surfaces. B. Large stumps located in areas to be excavated may be removed during grading operations, subject to the approval of the Engineer. 2.04 DISPOSAL OF MATERIAL A. All debris resulting from the clearing and grubbing work shall be disposed of by the Contractor as part of the work of this Contract. Material designated by the Engineer to be salvaged shall be stored on the construction site as directed by the Engineer for reuse in this Project or removal by others. B. Burning of any debris resulting from the clearing and grubbing work will not be permitted at the site. 2.05 WARNING AND BARRIER FENCE A. The fence shall be made of a visible, lightweight, flexible, high strength polyethylene material. The fence shall be MIRASAFE as manufactured by Mirafi, Inc., or equal. B. Physical Properties Fence: Color: International Orange Roll Size: 4'x 164' Roll weight: 34 lbs. Mesh opening: 1-1/2"x 3" Posts: ASTM Designation: ASTM 702 Length: 5 feet long (T-Type) Weight: 1.25 #/Foot(min) Area of Anchor Plate: 14 Sq. In. C. Drive posts 12 to 18 inches into ground every 10' to 12'. Wrap fence material around first terminal post allowing overlap of one material opening. Use metal tie wire or plastic tie wrap to fasten material to itself at top, middle and bottom. At final post, cut with utility knife or scissors ata point halfway across an opening. Wrap around and tie at final post in the same way as the first post. 32135-002102100:5/7/2014 02100-3 GAC Upgrades for the Crozet and Scottsville WTPs D. Use tie wire or tie wrap at intermediate posts and splices as well. Thread ties around a vertical member of the fence material and the post, and bind tightly against the post. For the most secure fastening, tie at top, middle and bottom. Overlap splices a minimum of four fence openings, tie as above, fastening both edges of the fence material splice overlap. - END OF SECTION - 32135-002102100:5/7/2014 02100-4 GAC Upgrades for the Crozet and Scottsville WTPs SECTION 02200 EARTHWORK PART 1 -- GENERAL 1.01 THE REQUIREMENT A. Furnish all labor, equipment and materials required to complete all work associated with excavation, including off-site borrow excavation, dewatering, backfill, drainage layers beneath and around structures, foundation and backfill stone, filter fabric, embankments, stockpiling topsoil and any excess suitable material in designated areas, in place compaction of embankments, backfill and subgrades beneath foundations and roadways, excavation support, disposing from the site all unsuitable materials, providing erosion and sedimentation control grading, site grading and preparation of pavement and structure subgrade,and other related and incidental work as required to complete the work shown on the Drawings and specified herein. B. All excavations shall be in conformity with the lines, grades, and cross sections shown on the Drawings or established by the Engineer. C. It is the intent of this Specification that the Contractor conduct the construction activities in such a manner that erosion of disturbed areas and off-site sedimentation be absolutely minimized. D. All work under this Contract shall be done in conformance with and subject to the limitations of the latest editions of the Virginia Department of Transportation Road and Bridge Specifications and the Virginia Erosion and Sediment Control handbook. 1.02 RELATED WORK SPECIFIED ELSEWHERE A. Requirements of related work are included in Division 1 and Division 2 of these Specifications. 1.03 REFERENCE SPECIFICATIONS, CODES, AND STANDARDS A. Without limiting the generality of the other requirements of the Specifications,all work herein shall conform to the applicable requirements of the following documents. All referenced Specifications, codes, and standards refer to the most current issue available at the time of Bid. 1. Virginia Department of Transportation Road and Bridge Specifications, latest edition. 2. American Society for Testing and Materials (ASTM): ASTM C 127 Test for Specific Gravity and Absorption of Coarse Aggregate. ASTM C 136 Test for Sieve Analysis of Fine and Coarse Aggregates. 32135-002102200:5/7/2014 02200-1 GAC Upgrades for the Crozet and Scottsville WTPs ASTM D 422 Particle Size Analysis of Soils. ASTM D 423 Test for Liquid Limit of Soils. ASTM D 424 Test for Plastic Limit and Plasticity Index of Soils. ASTM C 535 Test for Resistance to Degradation of Large Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine. ASTM D 698 Standard Method of Test for the Moisture - Density Relations of Soils Using a 5.5 lb. (2.5 kg) Rammer and a 12-inch (305 mm) Drop. ASTM D1556 Test for Density of Soil in Place by the Sand-Cone Method. ASTM D1557 Test for Moisture-Density Relations of Soils and Soil Aggregate Mixtures Using 10-lbs. (4.5 kg) Rammer and 18-inch (457 mm) Drop. ASTM D2049 Test Method for Relative Density of Cohesionless Soils. ASTM D2167 Test for Density of Soil in Place by the Rubber-Balloon Method. ASTM D2216 Test for Laboratory Determination of Water(Moisture)Content of Soil, Rock, and Soil Aggregate Mixtures. ASTM D2487 Test for Classification of Soils for Engineering Purposes. ASTM D2922 Test for Density of Soil and Soil-Aggregate in Place by Nuclear Methods (Shallow Depth). 1.04 SUBSURFACE CONDITIONS A. Information on subsurface conditions is referenced under Division 1, General Requirements. B. Attention is directed to the fact that there may be water pipes, storm drains and other utilities located in the area of proposed excavation. Perform all repairs to same in the event that excavation activities disrupt service. 1.05 SUBMITTALS A. In accordance with the procedures and requirements set forth in Section 01300-Submittals, the Contractor shall submit the following: 1. Name and location of all material suppliers. 2. Certificate of compliance with the standards specified above for each source of each material. 3. List of disposal sites for waste and unsuitable materials and all required permits for use of those sites. 32135-002102200:5/7/2014 02200-2 GAC Upgrades for the Crozet and Scottsville WTPs 4. Plans and cross sections of open cut excavations showing side slopes and limits of the excavation at grade. 5. Samples of synthetic filter fabric and reinforced plastic membrane with manufacturer's certificates or catalog cuts stating the mechanical and physical properties. Samples shall be at least one (1)foot wide and four(4)feet long taken across the roll with the warp direction appropriately marked. 6. Construction drawings and structural calculations for any types of excavation support required. Drawings and calculations shall be sealed by a currently registered Professional Engineer in the Commonwealth of Virginia. 7. Monitoring plan and pre-construction condition inspection and documentation of all adjacent structures, utilities, and roadways near proposed installation of excavation support systems. 8. Dewatering procedures. 1.06 PRODUCT HANDLING A. Soil and rock material shall be excavated,transported, placed,and stored in a manner so as to prevent contamination,segregation and excessive wetting. Materials which have become contaminated or segregated will not be permitted in the performance of the work and shall be removed from the site. 1.07 USE OF EXPLOSIVES A. When the use of explosives is necessary for the prosecution of the work, the Contractor shall exercise the utmost care not to endanger life or property. The Contractor shall be responsible for any and all damage or injury to persons or property resulting from the use of explosives. Use of explosives shall be in accordance with Specification Section 02202, Excavation by Blasting. PART 2 -- PRODUCTS 2.01 SELECT FILL A. Soils from the excavations meeting requirements stipulated herein with the exceptions of topsoil and organic material may be used as select fill for backfilling, constructing embankments, reconstructing existing embankments, and as structural subgrade support. B. Select fill used for embankment construction shall be a silty or clayey soil material with a Maximum Liquid Limit(LL)of 50 and a Plasticity Index(PI) between 7 and 20. C. Select fill used for backfilling shall either be material as described in Paragraph B above ora granular soil material with a Maximum Plasticity Index(PI) of 6. 32135-002102200:5/7/2014 02200-3 GAC Upgrades for the Crozet and Scottsville WTPs D. Regardless of material used as select fill, materials shall be compacted at a moisture content satisfactory to the Engineer,which shall be approximately that required to produce the maximum density except that the moisture content shall not be more than 1%below nor more than 4% above the optimum moisture content for the particular material tested in accordance with the ASTM D698. E. Select fill used as subgrade support shall be a coarse aggregate material meeting the gradation requirements of #57 or #78 aggregates in accordance with ASTM C-33, or Aggregate Base Course (ABC)as defined in Section 02207—Aggregate Materials. F. Where excavated material does not meet requirements for select fill, Contractor shall furnish off-site borrow material meeting the specified requirements herein. Determination of whether the borrow material will be paid for as an extra cost will be made based on Article 4 of the General Conditions, as amended by the Supplementary Conditions. When the excavated material from required excavations is suitable for use as backfill, bedding, or embankments, but is replaced with off-site borrow material for the Contractor's convenience, the costs associated with such work and material shall be borne by the Contractor. 2.02 TOPSOIL A. Topsoil shall be considered the surface layer of soil and sod, suitable for use in seeding and planting. It shall contain no mixture of refuse or any material toxic to plant growth. 2.03 FOUNDATION DRAINAGE SYSTEMS A. The Contractor shall provide foundation drainage systems as indicated on the Drawings and specified herein. The materials and placement shall be as indicated under Section 02712- Foundation Drainage Systems. 2.04 GEOTEXTILES A. The Contractor shall provide geotextiles as indicated on the Drawings and specified herein. The materials and placement shall be as indicated under Section 02274 - Geotextiles. PART 3 -- EXECUTION 3.01 STRIPPING OF TOPSOIL A. In all areas to be excavated, filled, paved, or graveled the topsoil shall be stripped to its full depth and shall be deposited in storage piles on the site, at locations designated by the Engineer, for subsequent reuse. Topsoil shall be kept separated from other excavated materials and shall be piled free of roots and other undesirable materials. 3.02 EXCAVATION A. All material excavated, regardless of its nature or composition, shall be classified as UNCLASSIFIED EXCAVATION. Excavation shall include the removal of all soil, rock, weathered rock, rocks of all types, boulders, conduits, pipe, and all other obstacles encountered and shown to be removed within the limits of excavation shown on the Drawings or specified herein. The cost of excavation shall be included in the Lump Sum Bid Price and no additional payment will be made for the removal of obstacles encountered within the excavation limits shown on the Drawings and specified herein. 32135-002102200:5/7/2014 02200-4 GAC Upgrades for the Crozet and Scottsville WTPs B. Where blasting is necessary to perform the required excavations, blasting shall be performed as stipulated in Section 02202, Excavation by Blasting. C. All suitable material removed in the excavation shall be used as far as practicable in the formation of embankments,subgrades,and shoulders, and at such other places as may be indicated on the Drawings or indicated by the Engineer. No excavation shall be wasted except as may be permitted by the Engineer. Refer to the drawings for specific location and placement of suitable excavated materials in the formation of embankments, backfill, and structural and roadway foundations. THE ENGINEER WILL DESIGNATE MATERIALS THAT ARE UNSUITABLE. The Contractor shall furnish off site disposal areas for the unsuitable material. Where suitable materials containing excessive moisture are encountered above grade in cuts, the Contractor shall construct above grade ditch drains prior to the excavation of the cut material when in the opinion of the Engineer such measures are necessary to provide proper construction. D. All excavations shall be made in the dry and in such a manner and to such widths as will give ample room for properly constructing and inspecting the structures and/or piping they are to contain and for such excavation support, pumping and drainage as may be required. Excavation shall be made in accordance with the grades and details shown on the Drawings and as specified herein. E. Excavation slopes shall be flat enough to avoid slides that will cause disturbance of the subgrade or damage of adjacent areas. Excavation requirements and slopes shall be as indicated in the Drawings. The Contractor shall intercept and collect surface runoff both at the top and bottom of cut slopes. The intersection of slopes with natural ground surfaces, including the beginning and ending of cut slopes, shall be uniformly rounded as shown on the Drawings or as may be indicated by the Engineer. Concurrent with the excavation of cuts the Contractor shall construct intercepting berm ditches or earth berms along and on top of the cut slopes at locations shown on the Drawings or designated by the Engineer. All slopes shall be finished to reasonably uniform surfaces acceptable for seeding and mulching operations. No rock or boulders shall be left in place which protrudes more than 1 foot within the typical section cut slope lines, and all rock cuts shall be cleaned of loose and overhanging material. All protruding roots and other objectionable vegetation shall be removed from slopes. The Contractor shall be required to submit plans of open-cut excavation for review by the Engineer before approval is given to proceed. F. It is the intent of these Specifications that all structures shall bear on an aggregate base, crushed stone or screened gravel bedding placed to the thickness shown on the Drawings, specified in these Specifications,or not less than 6-inches. Bedding for process piping shall be as specified in Section 15000 - Basic Mechanical Requirements, or as shown on the Drawings. G. The bottom of all excavations for structures and pipes shall be examined by the Engineer for bearing value and the presence of unsuitable material. If, in the opinion of the Engineer, additional excavation is required due to the low bearing value of the subgrade material, or if the in-place soils are soft, yielding, pumping and wet, the Contractor shall remove such material to the required width and depth and replace it with thoroughly compacted select fill, and/or crushed stone or screened gravel as indicated by the Engineer. Payment for such additional work ordered by the Engineer shall be made as an extra by a Change Order in accordance with the General Conditions and Division 1. No payment will be made for subgrade disturbance caused by inadequate dewatering or improper construction methods. 32135-002102200:5/7/2014 02200-5 GAC Upgrades for the Crozet and Scottsville WTPs H. All cuts shall be brought to the grade and cross section shown on the Drawings, or established by the Engineer, prior to final inspection and acceptance by the Engineer. I. Slides and overbreaks which occur due to negligence, carelessness or improper construction techniques on the part of the Contractor shall be removed and disposed of by the Contractor as indicated by the Engineer at no additional cost to the Owner. If grading operations are suspended for any reason whatsoever, partially completed cut and fill slopes shall be brought to the required slope and the work of seeding and mulching or other required erosion and sedimentation control operations shall be performed. J. Where the excavation exposes sludge,sludge contaminated soil or other odorous materials, the Contractor shall cover such material at the end of each workday with a minimum of 6-inches and a maximum of 24-inches of clean fill. The work shall be an odor abatement measure and the material shall be placed to the depth deemed satisfactory by the Engineer for this purpose. 3.03 EXCAVATION SUPPORT A. The Contractor shall furnish, place, and maintain such excavation support which may be required to support sides of excavation or to protect pipes and structures from possible damage and to provide safe working conditions. If the Engineer is of the opinion that at any point sufficient or proper supports have not been provided, he may order additional supports put in at the expense of the Contractor. The Contractor shall be responsible for the adequacy of all supports used and for all damage resulting from failure of support system or from placing, maintaining and removing it. B. Selection of and design of any proposed excavation support systems is exclusively the responsibility of the Contractor. Contractor shall submit drawings and calculations on proposed systems sealed by a Professional Engineer currently registered in the Commonwealth of Virginia. C. The Contractor shall exercise caution in the installation and removal of supports to insure that excessive or unusual loadings are not transmitted to any new or existing structure. The Contractor shall promptly repair at his expense any and all damage that can be reasonably attributed to installation or removal of excavation support system. D. Contractor shall monitor movement in the excavation support systems as well as movement at adjacent structures, utilities and roadways near excavation supports. Contractor shall submit a monitoring plan developed by the excavation support design engineer. All pre- construction condition assessment and documentation of adjacent structures on-site and off- site shall be performed by the Contractor. If any sign of distress such as cracking or movement occurs in any adjacent structure, utility or roadway during installation of supports, subsequent excavation, service period of supports, subsequent backfill and construction,or removal of supports, Engineer shall be notified immediately. Contractor shall be exclusively responsible for any damage to any roadway, structure, utility, pipes,etc.both on-site and off- site, as a result of his operations. 32135-002102200:5/7/2014 02200-6 GAC Upgrades for the Crozet and Scottsville WTPs E. All excavation supports shall be removed upon completion of the work except as indicated herein. The Engineer may permit supports to be left in place at the request and expense of the Contractor. The Engineer may order certain supports left permanently in place in addition to that required by the Contract. The cost of the materials so ordered left in place, less a reasonable amount for the eliminated expense of the removal work omitted, will be paid as an extra by a Change Order in accordance with the General Conditions and Division 1. Any excavation supports left in place shall be cut off at least two (2) feet below the finished ground surface or as directed by the Engineer. 3.04 PROTECTION OF SUBGRADE A. To minimize the disturbance of bearing materials and provide a firm foundation, the Contractor shall comply with the following requirements: 1. Use of heavy rubber-tired construction equipment shall not be permitted on the final subgrade unless it can be demonstrated that drawdown of groundwater throughout the entire area of the structure is at least 3 feet below the bottom of the excavation (subgrade). Even then, the use of such equipment shall be prohibited should subgrade disturbance result from concentrated wheel loads. 2. Subgrade soils disturbed through the operations of the Contractor shall be excavated and replaced with compacted select fill or crushed stone at the Contractor's expense as indicated by the Engineer. 3. The Contractor shall provide positive protection against penetration of frost into materials below the bearing level during work in winter months. This protection can consist of a temporary blanket of straw or salt hay covered with a plastic membrane or other acceptable means. 3.05 PROOFROLLING A. The subgrade of all structures and all areas that will support pavements or select fill shall be proofrolled. After stripping of topsoil, excavation to subgrade and prior to placement of fills, the exposed subgrade shall be carefully inspected by probing and testing as needed. Any topsoil or other organic material still in place, frozen, wet, soft, or loose soil, and other undesirable materials shall be removed. The exposed subgrade shall be proofrolled with a heavily loaded tandem-wheeled dump truck to check for pockets of soft material hidden beneath a thin crust of better soil. Any unsuitable materials thus exposed shall be removed and replaced with an approved compacted material. 3.06 DEWATERING A. The Contractor shall do all dewatering as required for the completion of the work. Procedures for dewatering proposed by the Contractor shall be submitted to the Engineer for review prior to any earthwork operations. All water removed by dewatering operations shall be disposed of in accordance with the Virginia Erosion and Sediment Control Law. B. The dewatering system shall be of sufficient size and capacity as required to control groundwater or seepage to permit proper excavation operations,embankment construction and reconstruction, subgrade preparation, and to allow concrete to be placed in a dry condition. The system shall include a sump system or other equipment,appurtenances and 32135-002102200:5/7/2014 02200-7 GAC Upgrades for the Crozet and Scottsville WTPs other related earthwork necessary for the required control of water. The Contractor shall drawdown groundwater to at least 3 feet below the bottom of excavations (subgrade)at all times in order to maintain a dry and undisturbed condition. C. The Contractor shall control, by acceptable means, all water regardless of source. Water shall be controlled and its disposal provided for at each berm, structure, etc. The entire periphery of the excavation areas shall be ditched and diked to prevent water from entering the excavation. The Contractor shall be fully responsible for disposal of the water and shall provide all necessary means at no additional expense to the Owner. The Contractor shall be solely responsible for proper design, installation, proper operation, maintenance,and any failure of any component of the system. D. The Contractor shall be responsible for and shall repair without cost to the Owner, any damage to work in place and the excavation, including damage to the bottom due to heave and including removal of material and pumping out of the excavated area. The Contractor shall be responsible for damages to any other area or structure caused by his failure to maintain and operate the dewatering system proposed and installed by the Contractor. E. The Contractor shall take all the steps that he considers necessary to familiarize himself with the surface and subsurface site conditions, and shall obtain the data that is required to analyze the water and soil environment at the site and to assure that the materials used for the dewatering systems will not erode, deteriorate, or clog to the extent that the dewatering systems will not perform properly during the period of dewatering. Copies of logs of borings and laboratory test results are available to the Contractor. This data is furnished for information only,and it is expressly understood that the Owner and Engineer will not be held responsible for any interpretations or conclusions drawn therefrom by the Contractor. F. Prior to the execution of the work, the Contractor, Owner and Engineer shall jointly survey the condition of adjoining structures. Photographs and records shall be made of any prior settlement or cracking of structures, pavements, and the like, that may become the subject of possible damage claims. 3.07 EMBANKMENTS A. The Contractor shall perform the construction of embankments in such a manner that cut and fill slopes will be completed to final slopes and grade in a continuous operation. The operation of removing excavation material from any cut and the placement of embankment in any fill shall be a continuous operation to completion unless otherwise permitted by the Engineer. B. Surfaces upon which embankments are to be constructed shall be stripped of topsoil, organic material, rubbish and other extraneous materials. After stripping and prior to placing embankment material, the Contractor shall compact the top 12-inches of in place soil as specified under Paragraph 3.09, COMPACTION. C. Any soft or unsuitable materials revealed before or during the in place compaction shall be removed as indicated by the Engineer and replaced with select fill. D. Ground surfaces on which embankments are to be placed shall be scarified or stepped in a manner which will permit bonding of the embankment with the existing surface. The embankment soils shall be as specified under Part 2-Products, and shall be deposited and 32135-002102200:5/7/2014 02200-8 GAC Upgrades for the Crozet and Scottsville WTPs spread in successive, uniform, approximately horizontal layers not exceeding 8-inches in compacted depth for the full width of the cross section, and shall be kept approximately level by the use of effective spreading equipment. Hauling shall be distributed over the full width of the embankment, and in no case will deep ruts be allowed to form during the construction of the embankment. The embankment shall be properly drained at all times. Each layer of the embankment shall be thoroughly compacted to the density specified under Paragraph 3.09, COMPACTION. E. The embankment or fill material in the layers shall be of the proper moisture content before rolling to obtain the prescribed compaction. Wetting or drying of the material and manipulation when necessary to secure a uniform moisture content throughout the layer shall be required. Should the material be too wet to permit proper compaction or rolling, all work on all portions of the embankment thus affected shall be delayed until the material has dried to the required moisture content. Samples of all embankment materials for testing, both before and after placement and compaction, will be taken at frequent intervals. From these tests, corrections, adjustments,and modifications of methods, materials,and moisture content will be made to construct the embankment. F. Where embankments are to be placed and compacted on hillsides, or when new embankment is to be compacted against embankments,or when embankment is built in part widths,the slopes that are steeper than 4:1 shall be loosened or plowed to a minimum depth of 6 inches or, if in the opinion of the Engineer, the nature of the ground is such that greater precautions should be taken to bind the fill to the original ground then benches shall be cut in the existing ground as indicated by Engineer. G. When rock and other embankment material are excavated at approximately the same time, the rock shall be incorporated into the outer portions of the embankments and the other material which meets the requirements for select fill shall be incorporated into the formation of the embankments. Stones or fragmentary rock larger than 4-inches in their greatest dimension will not be allowed within the top 6-inches of the final grade. Stones,fragmentary rock, or boulders larger than 12-inches in their greatest dimension will not be allowed in any portions of embankments and shall be disposed of by the Contractor as indicated by the Engineer. When rock fragments or stone are used in embankments, the material shall be brought up in layers as specified or directed and every effort shall be exerted to fill the voids with finer material to form a dense, compact mass which meets the densities specified for embankment compaction. 3.08 BACKFILLING A. All structures and pipes shall be backfilled with the type of materials shown on the Drawings and specified herein. Select fill shall be deposited in successive, uniform, approximately horizontal layers not exceeding 8-inches in compacted depth for the full width. Stones or fragmentary rock larger than 4-inches in their greatest dimension will not be allowed within the top 6-inches of the ground nor within 6 inches of pipes. No stone or fragmentary rock larger than 12-inches in their greatest dimension will be allowed for any portion of backfill. Compaction shall be in accordance with the requirements of Paragraph 3.09, COMPACTION. B. Where excavation support is used, the Contractor shall take all reasonable measures to prevent loss of support beneath and adjacent to pipes and existing structures when supports are removed. If significant volumes of soil cannot be prevented from clinging to the 32135-002102200:5/7/2014 02200-9 GAC Upgrades for the Crozet and Scottsville WTPs extracted supports, the voids shall be continuously backfilled as rapidly as possible. The Contractor shall thereafter limit the depth below subgrade that supports will be installed in similar soil conditions or employ other appropriate means to prevent loss of support. 3.09 COMPACTION A. The Contractor shall compact embankments, backfill,crushed stone,aggregate base,and in place subgrade in accordance with the requirements of this Section. The densities specified herein refer to percentages of maximum density as determined by the noted test methods. Compaction of materials on the project shall be in accordance with the following schedule: Density % Density % Max. Lift Thickness Std. Proctor Mod. Proctor as Compacted (D698) (D1557) Inches Embankments Beneath Structures* 98 95 8 Other Embankments 95 92 8 Backfill Around Structures 95 92 8 Backfill in Pipe Trenches 95 92 8 Crushed Stone Beneath Structures ** ** 12 Select Sand -- 98 8 Aggregate Base Course (ABC) -- 98 8 Beneath Pavements and Structures Crushed Stone Backfill ** ** 12 Crushed Stone Pipe Bedding ** ** 12 In place Subgrade Beneath Structures 98 95 Top 12-inches * Embankments beneath structures shall be considered to include a zone 10 feet out from the foundation of the structure extending down to the natural ground on a 45° slope. ** The aggregate shall be compacted to a degree acceptable to the Engineer by use of a vibratory compactor and/or crawler tractor. B. Field density tests will be made by the Engineer to determine if the specified densities have been achieved, and these tests shall be the basis for accepting or rejecting the compaction. In-place density tests will be performed in accordance with ASTM D 1556,ASTM D 2167,or ASTM D 2922. The Engineer will be the sole judge as to which test method will be the most appropriate. Failure to achieve the specified densities shall require the Contractor to re-compact the material or remove it as required. The Contractor shall, if necessary, increase his compactive effort by increasing the number of passes, using heavier or more suitable compaction equipment, or by reducing the thickness of the layers. The Contractor shall adjust the moisture contents of the soils to bring them within the optimum range by drying them or adding water as required. 32135-002102200:5/7/2014 02200-10 GAC Upgrades for the Crozet and Scottsville WTPs C. Testing will be performed as frequently as deemed necessary by the Engineer. As a minimum, one in-place density test shall be performed for each 1000 cubic yards of embankment placed and 500 cubic yards of backfill placed or one test performed each day for either. 3.10 REMOVAL OF EXCESS AND UNSUITABLE MATERIALS A. The Contractor shall remove and dispose of off-site all unsuitable materials. Within thirty (30)consecutive days after Notice to Proceed, the Contractor shall submit to the Engineer for review all required permits and a list of disposal sites for the unsuitable materials. If the disposal site is located on private property, the submittal shall also include written permission from the owner of record. B. All unsuitable materials shall be disposed of in locations and under conditions that comply with federal, state and local laws and regulations. C. The Contractor shall obtain an off-site disposal area prior to beginning demolition or excavation operations. D. All excess and unsuitable materials shall be hauled in trucks of sufficient capacity and tight construction to prevent spillage. Trucks shall be covered to prevent the propagation of dust. E. When all excess and unsuitable material disposal operations are completed,the Contractor shall leave the disposal sites in a condition acceptable to the Owner and Owner(s)of the disposal site(s). 3.11 BORROW EXCAVATION A. Description The work covered by this section consists of the excavation of approved material from borrow sources and the hauling and utilization of such material as required on the Drawings or directed by the Engineer. It shall also include the removing, stockpiling,and replacement of topsoil on the borrow source; the satisfactory disposition of material from the borrow source which is not suitable for use; and the satisfactory restoration of the borrow source and haul roads to an acceptable condition upon completion of the work. Borrow excavation shall not be used before all available suitable unclassified excavation has been used for backfill and incorporated into the embankments. B. Coordination with Seeding Operations The Contractor shall coordinate the work covered by this section with the construction of embankments so that the requirements of Section 02200 are met. C. Materials All material shall meet the requirements of Division 2 shown below: Borrow Material Section 02200, Subsection 2.01 -Select Fill 32135-002102200:5/7/2014 02200-11 GAC Upgrades for the Crozet and Scottsville WTPs D. Construction Methods 1. General The surface of the borrow area shall be thoroughly cleared and grubbed and cleaned of all unsuitable material including all organics, topsoil, etc., before beginning the excavation. Disposal of material resulting from clearing and grubbing shall be in accordance with Section 02100. Each borrow operation shall not be allowed to accumulate exposed, erodible slope area in excess of 1 acre at any one given time without the Contractor's beginning permanent seeding and mulching of the borrow source or other erosion control measures as may be approved by the Engineer. The topsoil shall be removed and stockpiled at locations that will not interfere with the borrow operations and that meet the approval of the Engineer. Temporary erosion control measures shall be installed as may be necessary to prevent the erosion of the stockpile material. Once all borrow has been removed from the source or portion thereof, the stockpiled topsoil shall be spread uniformly over the source. Where it is necessary to haul borrow material over existing roads, the Contractor shall use all necessary precautions to prevent damage to the existing roads. The Contractor shall also conduct his hauling operations in such a manner as to not interfere with the normal flow of traffic and shall keep the traffic lanes free from spillage at all times. 2. Owner Furnished Sources Where borrow sources are furnished by the Owner the location of such sources will be as designated on the Drawings or as directed by the Engineer. The Owner will furnish the necessary haul road right-of-way at locations designated by the Engineer. All haul roads required shall be built, maintained, and when directed by the Engineer, obliterated, at no cost to the Owner. Where the haul road is to be reclaimed for cultivation the Contractor shall plow or scarify the area to a minimum depth of 8 inches. The borrow sources shall be left in a neat and presentable condition after use. All slopes shall be smoothed, rounded, and constructed not steeper than 3:1. Where the source is to be reclaimed for cultivation the source shall be plowed or scarified to a minimum depth of 8 inches,disc harrowed,and terraces constructed. The source shall be graded to drain such that no water will collect or stand and a functioning drainage system shall be provided. All sources shall be seeded and mulched in accordance with Section 02910. 32135-002102200:5/7/2014 02200-12 GAC Upgrades for the Crozet and Scottsville WTPs 3. Contractor Furnished Sources Prior to the approval of any off-site borrow source(s) developed for use on this project, the Contractor shall obtain certification from the State Historic Preservation Officer of the Virginia Department of Historic Resources certifying that the removal of the borrow material from the borrow source(s) will have no effect on any known district, site building,structure, or object that is included or eligible for inclusion in the National Register of Historic Places. A copy of this certification shall be furnished to the Engineer prior to performing any work on the proposed borrow source. The approval of borrow sources furnished by the Contractor shall be subject to the following conditions: a. The Contractor shall be responsible for acquiring the right to take the material and any rights of access that may be necessary; for locating and developing the source; and any clearing and grubbing and drainage ditches necessary. Such right shall be in writing and shall include an agreement with the Owner that the borrow source may be dressed, shaped, seeded, mulched, and drained as required by these Specifications after all borrow has been removed. b. Except where borrow is to be obtained from a commercial source, the Contractor and the property owner shall jointly submit a borrow source development, use, and reclamation plan to the Engineer for his approval prior to engaging in any land disturbing activity on the proposed source other than material sampling that may be necessary. The Contractor's plan shall address the following: (1) Drainage The source shall be graded to drain such that no water will collect or stand and a functioning drainage system shall be provided. If drainage is not practical, and the source is to serve as a pond, the minimum average depth below the water table shall be 4 feet or the source graded so as to create wetlands as appropriate. (2) Slopes The source shall be dressed and shaped in a continuous manner to contours which are comparable to and blend in with the adjacent topography, but in no case will slopes steeper than 3:1 be permitted. (3) Erosion Control The plan shall address the temporary and permanent measures that the Contractor intends to employ during use of the source and as a part of the reclamation. The Contractor's plan shall provide for the use of staged permanent seeding and mulching on a continual basis while the source is in use and the immediate total reclamation of the source when no longer needed. 32135-002102200:5/7/2014 02200-13 GAC Upgrades for the Crozet and Scottsville WTPs 4. Maintenance During construction and until final acceptance the Contractor shall use any methods approved by the Engineer which are necessary to maintain the work covered by this section so that the work will not contribute to excessive soil erosion. - END OF SECTION - 32135-002102200:5/7/2014 02200-14 GAC Upgrades for the Crozet and Scottsville WTPs SECTION 02202 EXCAVATION BY BLASTING PART 1 -- GENERAL 1.01 THE REQUIREMENT A. Furnish all labor, equipment and materials required to drill, blast, loosen, excavate, and dispose material to complete the work shown on the Drawings and specified herein. B. The work shall include, but not be limited to: 1. Blast round design. 2. Planning and execution of appropriate site-specific safety measures to be employed during all blasting operations, and the safe handling and storage of high explosives and blasting agents. 3. Drilling blast holes, loading blast holes with explosives, and wiring and safe detonation of blast rounds. 4. Removal from the site of all excess excavated soil, debris, and rock as indicated in the contract Documents, or as directed by the Engineer, and disposal of excess materials at a permitted disposal site. 5. Dewatering and maintenance of groundwater and surface water in all excavations. 6. Performance of all surveys necessary to establish and verify the lines and grades, and to determine the amount of material removed. 7. Implementation of monitoring program to monitor condition of existing structures and utilities in vicinity of proposed blasting operations to insure existing features remain undamaged by blasting procedures. C. All excavations shall be in conformity with the lines, grades, and cross sections shown on the Drawings or established by the Engineer. D. It is the intent of this Specification that the Contractor conduct the construction activities in such a manner that erosion of disturbed areas and off-site sedimentation be absolutely minimized, both at the excavation site and at the disposal site, as well as along any haul routes used. 1.02 RELATED WORK SPECIFIED ELSEWHERE A. Section 02100— Clearing, Grubbing, and Site Preparation B. Section 02140— Dewatering 32135-002102202:5/7/2014 02202-1 GAC Upgrades for the Crozet and Scottsville WTPs C. Section 02200 — Earthwork D. Section 02276 — Erosion and Sedimentation Control 1.03 REFERENCE SPECIFICATIONS, CODES, AND STANDARDS A. Virginia Occupational Safety and Health Standards in Construction for Blasting & Use of Explosives. 1.04 SUBSURFACE CONDITIONS A. Reference is made to Section 01010 — Summary of Work of the Specifications for the identification of those surveys and investigation reports of subsurface or latent physical conditions at the site or otherwise affecting performance of the work which have been relied upon by Engineer in preparing the Drawings and Specifications. B. Attention is directed to the fact that there may be other water pipes, storm drains, sewer lines, electric conduits, and other utilities located in the area of the proposed excavation. Contractor shall perform all repairs to same in the event that excavation activities should disrupt service. 1.05 SUBMITTALS A. In accordance with the procedures and requirements set forth in Section 01300-Submittals, the Contractor shall submit the following at least 30 working days prior to beginning any blasting operations: 1. Names, addresses, telephone numbers, and qualifications of the blasting subcontractor(s) and explosives supplier(s) that will be used, including the designated Blaster-In-Charge. 2. Copies of Training Certificates for the designated Blaster-In-Charge, blasting foreman and any other key personnel that will be responsible for the work, showing that they have received specialized training in the proper handling of explosives. 3. A Blasting Plan, indicating the methods, materials and equipment to be used. The Blasting Plan should indicate the types of explosives to be used, drilling patterns, and a general layout and schedule for executing the work in accordance with state regulations. 4. A ground vibration and air blast monitoring plan, indicating structures that will be monitored, monitoring equipment that will be used, and personnel that will perform the monitoring. B. At least 24 hours before each blast round, Contractor shall submit a detailed blast round design plan to the Engineer's on-site representative. The blasting plan submitted is for quality control and record keeping purposes. Review by the Engineer shall not relieve the Contractor of his responsibilities as provided herein. The blast round design submittals shall include: 1. Location (state, grid coordinates)and limits of the shot. 32135-002102202:5/7/2014 02202-2 GAC Upgrades for the Crozet and Scottsville WTPs 2. Number, diameter, and depth of blast holes to be detonated in the round,and a plan showing the drill hole pattern, spacing and distance to the free face. 3. Depth of overburden. 4. Total weight of explosives in the round and the types of explosives to be used. 5. Loading diagram showing the location of explosives, primers, and initiators; and location, depth, and type of stemming to be used in each hole. 6. Initiation sequence, including delay timer and delay system,total weight of explosive to be detonated on each delay, and a list of the timing of the delays. 7. Manufacturer's data sheet for all explosives, primers, and initiators to be used. 8. Planned seismic monitoring positions, distances from the blast round, and seismograph types to be used to monitor vibrations and air blast overpressures. 9. Type and amount of blasting mats and/or depth of soil cover to be used over the top surface of the shot. 10. Any other information required by applicable state and federal regulations. C. Within 24 hours after each blast round, Contractor shall submit a blasting report to the Engineer. The blasting report shall include: 1. Date and time of shot. 2. Foreman's name. 3. Number and depth of holes detonated. 4. Weather conditions at the time of detonation. 5. Type of explosives and detonators used. 6. Peak particle velocity of ground motion and primary frequency for all ground vibration monitoring stations. 7. Peak air blast overpressure measured. 8. Distance from the blast round to each monitoring station for vibrations and air blast. 9. Amount of explosive used in each hole,and maximum weight of explosive detonated on any single delay in the blast round. 32135-002102202:5/7/2014 02202-3 GAC Upgrades for the Crozet and Scottsville WTPs 1.06 USE OF EXPLOSIVES A. When the use of explosives is necessary for the prosecution of the work, the Contractor shall exercise the utmost care not to endanger life or property. The Contractor shall be responsible for any and all damage or injury to persons or property resulting from the use of explosives. B. All explosives shall be stored in a secure manner, in compliance with all laws, and all such storage places shall be marked clearly"DANGEROUS EXPLOSIVES". C. The Contractor shall notify any public utility company having facilities in close proximity to the site of the work of his intention to use explosives. This notice shall be given sufficiently in advance to enable the utility companies to take whatever steps they may consider necessary to protect their property from injury. The Contractor shall also give the Engineer, all occupants of adjacent property, and all other Contractors working in or near the Project, notice of his intention to use explosives. PART 2 -- PRODUCTS 2.01 MATERIAL REQUIRING EXCAVATION BY BLASTING A. Any material occupying an original volume of at least one cubic yard which cannot be excavated with a single-tooth ripper drawn by a crawler tractor having draw bar pull rated at not less than 60,000 pounds at a velocity of 1.0 mph (Caterpillar D8N or equivalent). 2.02 INITIATORS A. Contractor is advised of the possible presence of high-voltage electric power lines and radio towers at the project site. Only non-electric type initiators may be used. PART 3 -- EXECUTION 3.01 BLASTING OPERATIONS A. Explosives shall be of such quantity and power and shall be used in such locations as will neither open seams nor otherwise disturb the material outside the prescribed limits of excavation. As the excavation approaches its final limits,the depth of holes for blasting and the amount of explosives used for each hole shall be reduced so that the underlying or adjacent rock will not be disturbed or shattered. B. BLASTING SHALL NOT BE PERFORMED WITHIN 100 FEET OF NEWLY PLACED CONCRETE THAT HAS CURED LESS THAN 7 DAYS. NO BLASTING SHALL BE PERMITTED WITHIN 50 FEET OF ANY EXISTING STRUCTURE OR ANY NEW STRUCTURE IN PROGRESS. 3.02 BLAST MONITORING A A pre-construction condition inspection and documentation of adjacent structures on-site and off-site shall be performed by the Contractor. The Contractor shall exercise the utmost care not to damage property on-site and off-site. The Contractor shall notify each adjoining 32135-002102202:5/7/2014 02202-4 GAC Upgrades for the Crozet and Scottsville WTPs property owner within 5000 feet of the site of the anticipated ground vibrations and noise which will occur due to his blasting operations. This notice shall be given 30 days in advance to enable the adjacent property owners to take whatever precautions they may consider necessary. The Contractor shall limit his operations to minimize any disturbance to the adjacent property owners. Motorists on adjacent roadways shall be notified in accordance with state regulations. The Contractor shall be responsible for any damage to any structure or utility line, pipes, etc., on-site and off-site as a result of his operations. B. For each blast round, Contractor shall monitor and record noise and air blast overpressures at the site perimeter nearest the blast location and at the on-site or off-site structure located nearest to the round. Peak air blast overpressure shall not exceed 0.018 psi, measured at the site perimeter. C. The site of every blast round shall be sufficiently covered with blasting mats or other devices to prevent any flying debris. The number and type of blasting mats must be satisfactory to the Engineer. The Contractor will be fully responsible for any damage caused by flying debris, both to on-site and off-site properties. D. Whenever blasting is to be performed within 2500 feet of any structure,the Contractor shall measure the peak particle velocities of ground vibration resulting from each blast at the structure. Vibrations shall be monitored utilizing a seismograph capable of providing a record of particle velocity and frequency along three mutually perpendicular axes utilizing internal calibration. Measured peak particle velocity of ground motion at the monitored structure shall not exceed the values shown in the following graph: 10 m - 2.0 inch/sec • E • u UNACCEPTABLE 0 > 1 — m _u - a ro a _ `5 0.5 inch/sec m a ACCEPTABLE —0.19 inch/sec 0.1 1 10 100 Frequency(Hertz) - END OF SECTION - 32135-002102202:5/7/2014 02202-5 GAC Upgrades for the Crozet and Scottsville WTPs [THIS PAGE INTENTIONALLY LEFT BLANK] SECTION 02207 AGGREGATE MATERIALS PART 1 -- GENERAL 1.01 THE REQUIREMENT A. The Contractor shall furnish all labor,equipment and materials required to complete all work associated with the installation of aggregate material beneath foundations,as backfill and as roadway subgrades and other related and incidental work as required to complete the work shown on the Drawings and specified herein. 1.02 RELATED WORK SPECIFIED ELSEWHERE A. Section 01090 - Reference Standards B. Section 02200 - Earthwork C. Section 02276 - Erosion and Sedimentation Control D. Section 02510 - Paving and Surfacing E. Section 02712 - Foundation Drainage Systems F. Section 02910 - Final Grading and Landscaping 1.03 REFERENCE SPECIFICATIONS, CODES AND STANDARDS A. Without limiting the generality of the other requirements of the Specifications,all work herein shall conform to the applicable requirements of the following documents. All referenced specifications, codes, and standards refer to the most current issue available at the time of Bid. 1. Virginia Department of Transportation (VDOT) Roads and Bridges Specifications. 2. ASTM C 127 Test for Specific Gravity and Absorption of Coarse Aggregate. 3. ASTM C 136 Test for Sieve Analysis of Fine and Coarse Aggregates. 4. ASTM C 535 Test for Resistance to Degradation of Large Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine. 1.04 SUBMITTALS N A. Submit the following in accordance with Section 01300, Submittals. 1. Materials gradation and certification. 32135-002102207:5/7/2014 02207-1 GAC Upgrades for the Crozet and Scottsville WTPs 2. ASTM C127, ASTM C136, and ASTM C535 test results PART 2 -- PRODUCTS 2.01 CRUSHED STONE, SCREENED GRAVEL and AGGREGATE BASE COURSE (ABC) A. Crushed stone or screened gravel shall meet the requirements of Aggregate Standard Size No. 57 or No. 67 as defined by VDOT Standard Specifications. B. ABC shall meet the requirements of ABC as defined by VDOT Standard Specifications. 2.02 SELECT SAND A. Select sand shall meet the requirements of Section 202 of the VDOT Standard Specifications for materials and gradation. The size used shall be Standard Size A or B as listed and defined in Table II-1, "Fine Aggregate", of the VDOT Standard Specifications. PART 3 -- EXECUTION 3.01 CRUSHED STONE, SCREENED GRAVEL AND AGGREGATE BASE COURSE (ABC) A. Contractor shall install crushed stone, screened gravel and ABC in accordance with the VDOT Standard Specifications and as shown on the Drawings and indicated in the Contract Documents. 1. Unless otherwise stated herein or shown on the Drawings, all mat foundations (bottom slabs)for the proposed structures shall have a blanket of crushed stone or ABC 6-inches thick minimum placed directly beneath the proposed mat. The blanket shall extend a minimum of 12 inches beyond the extremities of the mat. 2. For subgrade preparation at structures and structural fill, the foundation material shall be ABC where specifically specified on Drawings, otherwise, crushed stone or screened gravel shall be used. 3. For ground under drains, pipe bedding, and drainage layers beneath structures the coarse aggregate shall meet the requirements of aggregate standard Size No.57 or No. 67, as defined by VDOT Standard Specifications. 3.02 SELECT SAND A. Contractor shall install select sand in accordance with the VDOT Standard Specifications and as shown on the Drawings and indicated in the Contract Documents. - END OF SECTION - Now- 32135-002102207:5/7/2014 02207-2 GAO Upgrades for the Crozet and Scottsville WTPs SECTION 02276 EROSION AND SEDIMENTATION CONTROL PART 1 -- GENERAL 1.01 THE REQUIREMENTS A. The Contractor shall employ a Responsible Land Disturber certified in the Commonwealth of Virginia who is responsible for implementing Best Management Practices(BMPs)to prevent and minimize erosion and resultant sedimentation in all cleared and grubbed areas during and after construction. This item covers the Work necessary for the installation of structure and measures for the prevention and control of soil erosion. The Contractor shall furnish all material, labor and equipment necessary for the proper installation, maintenance, inspection, monitoring, reporting, and removal (where applicable) of erosion prevention and control measures and to cause compliance with the General Virginia Pollutant Discharge Elimination System (VPDES) Permit Regulation for Discharges of Storm Water From Construction Activities (9 VAC 25-180) and VPDES General Permit No. VAR10 under this Section. B. All excavations shall be in conformity with the lines, grades, and cross sections shown on the Drawings or established by the Engineer. C. It is the intent of this Specification that the Contractor conduct the construction activities in such a manner that erosion of disturbed areas and off-site sedimentation be absolutely minimized. D. All Work under this Contract shall be done in conformance with and subject to the limitations of the Virginia Erosion and Sediment Control Handbook(VESCH)and the Virginia Erosion and Sediment Control Law, Regulations and Certification Regulations, as adopted in the Code of Virginia Title 10-1, Chapter 5,Article 4 and Sections 4VAC30-50 and 4VAC50-50 of the Virginia Administration Code. E. The Contractor shall comply with all applicable minimum standards set in the Virginia Erosion and Sediment Control Handbook. The following excerpts from the VESCH Minimum Standards are particularly important: 1. Permanent or temporary soil stabilization shall be applied to denuded areas within seven days after final grade is reached on any portion of the site. Temporary soil stabilization shall be applied within seven days to denuded areas that may not be at final grade but will remain dormant (undisturbed) for longer than 30 days. Permanent stabilization shall be applied to areas that are to be left dormant for more than one year. N 2. A permanent vegetative cover shall be established on denuded areas not otherwise permanently stabilized. Permanent vegetation shall not be considered established until a ground cover is achieved that, in the opinion of the local program administrator or his designated agent, is uniform, mature enough to survive and will inhibit erosion. 32135-002102276V::5/7/2014 02276-1 GAC Upgrades for the Crozet and Scottsville WTPs 3. Stabilization measures shall be applied to earthen structures such as dams, dikes and diversions immediately after installation. 4. All temporary erosion and sediment control measures shall be removed within 30 days after final site stabilization or after the temporary measures are no longer needed, unless otherwise authorized by the local program administrator. Trapped sediment and the disturbed soil areas resulting from the deposition of temporary measures shall be permanently stabilized to prevent further erosion and sedimentation. F. Due to the nature of the Work required by this Contract, it is anticipated that the location and nature of the erosion and sedimentation control devices will be adjusted on several occasions to reflect the current phase of construction. The construction schedule adopted by the Contractor will impact the placement and need for specific devices required for the control of erosion. The Contractor shall develop and implement such additional techniques as may be required to minimize erosion and off-site sedimentation. The location and extent of erosion and sedimentation control devices shall be revised at each phase of construction that results in a change in either the quantity or direction of surface runoff from constructed areas. All deviations from the erosion and sedimentation control provisions shown on the Drawings shall have the prior acceptance of the Engineer. 1.02 RELATED WORK SPECIFIED ELSEWHERE A. Section 02100 —Clearing, Grubbing, and Site Preparation B. Section 02200 — Earthwork C. Section 02910 — Final Grading and Landscaping 1.03 REFERENCE SPECIFICATIONS, CODES AND STANDARDS A. Without limiting the generality of other requirements of these specifications, all Work hereunder shall conform to the applicable requirements of the referenced portions of the following documents, to the extent that the requirements therein are not in conflict with the provisions of this Section. 1. Code of Virginia, Title 10.1, Chapter 5, Article 4 2. Virginia Erosion and Sediment Control Handbook (VESCH), latest edition. 3. General Virginia Pollutant Discharge Elimination System(VPDES)Permit Regulation for Discharges of Storm Water From Construction Activities (9 VAC 25-180) and VPDES General Permit No. VAR10. 4. Erosion and Sediment Control Plan as required by the VPDES Permit. 5. Maintenance and Inspection Procedures as required by the VPDES Permit B. See Specification Section 01090 - Reference Standards. 32135-002\02276V::5/7/2014 02276-2 GAC Upgrades for the Crozet and Scottsville WTPs 1.04 REGULATORY COMPLIANCE A. Land disturbance activities are not authorized to begin until after all required erosion and sediment control permits are obtained from the United States, Commonwealth of Virginia, and Albemarle County. Contractor is the Co-Primary Permittee and Operator under the provisions of the VPDES Permit. As such, Contractor will be required to sign certain certifications as described in the VPDES Permit. Contractor shall comply with requirements specified in the Contract Documents or by the Engineer. Contractor shall also comply with all other laws, rules, regulations, ordinances and requirements concerning soil erosion and sediment control established in the United States, the Commonwealth of Virginia, and Albemarle County. The following documents and the documents referenced therein define the regulatory requirements for this Section 02276. 1. VPDES PERMIT: The Virginia Pollution Discharge Elimination System (VPDES) General Permit(VAR 10)for Discharges of Storm Water from Construction Activity governs land disturbance or construction activities of one (1) acre or more. On applicable sites, Contractor is responsible for complying with terms and conditions of this permit. 2. Manual for Erosion and Sediment Control: Contractor shall follow Practices and Standards of the Virginia Erosion and Sediment Control Handbook(VESCH), Third Edition, or latest. 3. SWP3: When a Storm Water Pollution Prevention Plan (SWP3) is provided in the Contract Documents, the Contractor shall follow the practices described in the SWP3. (See the Appendix for the SWP3, if applicable.) 1.05 SUBMITTALS A. Prior to the start of the Work, the Contractor shall prepare and submit a plan for applying the temporary and permanent erosion and siltation control measures as shown on the Owner's approved Erosion and Sediment Control Plan. Construction Work shall not commence until the schedule of Work and the methods of operations have been reviewed and approved. B. In accordance with the procedures and requirements set forth in the General Conditions Division 1 and Section 01300, the Contractor shall submit the following: 1. Name and location of all material suppliers. 2. Certificate of compliance with the standards specified above for each source of each material. 3. List of disposal sites for waste and unsuitable materials and all required permits for use of those sites. 1.06 EROSION AND SEDIMENTATION CONTROL DEVICES A. The following erosion and sedimentation control devices shall be incorporated into the Work. Other devices, as necessary and acceptable to the Engineer shall be installed as required. 32935-002102276V.:5/7/2014 02276-3 GAO Upgrades for the Crozet and Scottsville WTPs 1. Temporary Sediment Traps shall be constructed at the locations shown on the Drawings, at the termination of all Temporary Diversions diverting sediment laden runoff,and at other locations indicated by the Engineer. Temporary Sediment Traps shall be constructed by excavating the appropriate size rectangular basin and constructing a rock-fill dam on the discharge end to form a sediment trap.Temporary Sediment Traps shall be spaced to limit the maximum tributary drainage area to less than or equal to 3 acres. Temporary Sediment Traps shall be designed, installed and maintained in accordance with the requirements of Section 3.13 of the VESCH. 2. Temporary Diversions shall be constructed at the locations shown on the Drawings, and at other locations indicated by the Engineer. Dimensions shall be as shown on the Drawings. All diversion ditches transporting sediment-laden runoff shall terminate in Temporary Sediment Traps. Temporary Diversions shall be designed, installed and maintained in accordance with the requirements of Section 3.12 of the VESCH. 3. Silt Fence shall be constructed at the locations shown on the Drawings,and at other locations indicated by the Engineer. Silt fence shall not be installed across streams, ditches or waterways. Silt Fence shall be designed, installed and maintained in accordance with requirements of Section 3.05 of the VESCH. 4. Rock Check Dams shall be constructed at the locations shown on the Drawings,and at other locations indicated by the Engineer. Dimensions shall be as shown on the Drawings. Rock Check Dams shall be designed, installed and maintained in accordance with the requirements of Section 3.20 of the VESCH. 5. Block and Gravel Drop Inlet Sediment Filters shall be constructed at the locations shown on the Drawings, and at other locations indicated by the Engineer. Dimensions shall be as shown on the Drawings. Block and Gravel Drop Inlet Sediment Filters shall be designed, installed and maintained in accordance with the requirements of Section 3.07 of the VESCH. 6. Block and Gravel Curb Inlet Sediment Filters shall be constructed at the locations shown on the Drawings, and at other locations indicated by the Engineer. Gravel Curb Inlet Sediment Filters shall be designed, installed and maintained in accordance with the requirements of Section 3.07 of the VESCH. 7. Culvert Inlet Protection shall be constructed at the locations shown on the Drawings, and at other locations indicated by the Engineer. Culvert Inlet Protection shall be designed, installed and maintained in accordance with the requirements of Section 3.08 of the VESCH. 8. Temporary and Permanent Stormwater Conveyance Channels shall be installed at the locations shown on the Drawings, and at other locations indicated by the Engineer. Channels and Channel Linings shall be designed, installed and maintained in accordance with the requirements of Sections 3.17 and 3.36 of the VESCH. 32135-002\02276V::5/7/2014 02276-4 GAC Upgrades for the Crozet and Scottsville WTPs 9. Riprap Outlet Protection shall be constructed at the locations shown on the Drawings and at other locations indicated by the Engineer. All Riprap Outlet Protection shall be designed, installed and maintained in accordance with the requirements of Sections 3.18 and 3.19 of the VESCH. 10. Temporary Construction Entrances shall be located at points where vehicles enter and leave a construction site and at other locations indicated by the Engineer. Temporary Construction Entrances shall be designed, installed and maintained in accordance with the requirements of Section 3.02 of the VESCH. 1.07 GUARANTEE A. All restoration and revegetation Work shall be subject to the one-year guarantee period of the Contract as specified in the General Conditions. PART 2 -- MATERIALS 2.01 MATERIALS A. Materials for use in erosion and sedimentation control devices shall be in accordance with the Virginia Erosion and Sediment Control Handbook. 2.02 TEMPORARY SEDIMENT TRAPS A. Temporary Sediment Traps shall be constructed as shown on the Contract Drawings and as specified herein. The Temporary Sediment Traps shall be constructed and maintained in accordance with Part 3 of this Section, and Section 3.13 of the VESCH,to the satisfaction of the Engineer and/or local program administrator until a vegetative ground cover has been established. The cost of the Temporary Sediment Traps shall include the excavation, grading, diversion ditches, stone for erosion control, washed stone, geotextile, etc. and all maintenance activities required. 2.03 TEMPORARY DIVERSIONS A. Temporary Diversions shall be constructed as shown on the Contract Drawings and as specified herein. Temporary Diversions shall be installed and maintained in accordance with Part 3 of this Section, and Section 3.12 of the VESCH, to the satisfaction of the Engineer and/or local program administrator until the site has been stabilized. The cost of Temporary Diversions shall include the excavation and all maintenance and restoration activities required. 2.04 SILT FENCE A. Silt Fence shall be installed and maintained in accordance with the Maintenance paragraph, and Section 3.05 of the VESCH, to the satisfaction of the Engineer until the site has been stabilized. The cost of Silt Fence shall include the fabric, posts,wire fabric, excavation and all maintenance and restoration activities required. 32135-002102276V::5/7/2014 02276-5 GAC Upgrades for the Crozet and Scottsville WTPs B. Silt Fence shall be a woven geotextile filter fabric made specifically for sediment control. Filter fabric shall not rot when buried and shall resist attack from soil chemicals,alkalies and acids in the pH range from 2 to 13, and shall resist damage due to prolonged ultraviolet exposure. Filter fabric shall be Type FX-11, as manufactured by Carthage Mills, Type 910SC, as manufactured by Synthetic Industries, Inc., Amoco 2130 as manufactured by Amoco Fabrics & Fibers Co. C. Filter fabric for the silt fence shall have the following minimum properties: Value Test Method Grab Tensile Strength 100 lbs ASTM D 4632 Grab Elongation 15% ASTM D 4632 Trapezoid Tear Strength 50 lbs ASTM D 4533 Mullen Burst Strength 265 lbs ASTM D 3786 Puncture Strength 58 lbs ASTM D 4833 Retained Strength (500 hrs. accelerated UV exposure) 80% ASTM D 4355 Filtration Efficiency 75% VTM-51 Flow Rate 10/gal/min/ft.2 ASTM D 4491 Height 36 inches D. Posts for silt fence shall be steel and shall have the following properties: ASTM Designation: ASTM A702 Length: 5-Feet Long (T-Type) Weight: 1.25 lbs/foot(min.) Area of Anchor Plate: 14 Sq. In. Note: Five (T) Fasteners shall be furnished with each post. E. Wire Fabric for the silt fence shall have the following properties: Wire Fabric Designation: 832-12-10-12.5 Class 1 Designation: ASTM A116 Width: 32" Number of Line Wires: 8 Stay Wire Spacing: 12" Line and Stay Wires: 12.5 Ga. Top and Bottom Wires: 10 Ga. Wire Coating: ASTM Class 1 Zinc Coating 32135-002102276V:5/7/2014 02276-6 GAC Upgrades for the Crozet and Scottsville WTPs 2.05 RIP RAP A. The Contractor shall place rip rap as shown on the Drawings and as specified in Section 414 of the VDOT Road and Bridge Specifications. The stone for rip rap shall consist of field stone or rough unhewn quarry stone. The stone shall be sound, durable, and free from seams, cracks, or other structural defects. The rip rap shall be as specified on the Drawings. 2.06 CULVERT INLET PROTECTION A. Culvert Inlet Protection shall be constructed as shown on the Drawings and as specified herein. The culvert inlet protection shall be constructed at the upstream end of all culverts as indicated and maintained in accordance with Part 3 of this Section, and Section 3.08 of the VESCH,to the satisfaction of the Engineer until the site has been stabilized. The cost of the culvert inlet protection shall include the excavation, grading, stone for erosion control, riprap, etc. and all maintenance activities required. 2.07 STRAW WITH NET TEMPORARY SOIL STABILIZATION BLANKET (SSB) A. The Contractor shall place straw with net temporary channel and slope SSB as shown on the Drawings. The blanket shall consist of clean wheat straw from agricultural crops made into a knitted straw blanket that is machine assembled. The straw shall be evenly distributed throughout the blanket. The blanket shall be covered with a photodegradable synthetic mesh attached to the straw with degradable thread. B. The Contractor shall place the straw with net temporary channel and slope SSB where directed immediately after the channel or slope has been properly graded and prepared, fertilized, and seeded. The netting shall be on top with the straw in contact with the soil. C. The Contractor will immediately repair or replaced section of straw with net temporary channel and slope SSB which is not functioning properly or has been damaged in any way until a stable growth of grass has been established. D. Straw with net SSB shall be North American Green S150 matting, American Excelsior Co., Curlex I, Contech SFB1, or equal with a minimum shear stress value of 1.50 lb./ft.2 2.08 CURLED WOOD OR COCONUT FIBER TEMPORARY SOIL STABILIZATION BLANKET (SSB) A. The Contractor shall place curled wood or coconut fiber channel and slope SSB in channels or on slopes as shown on the Drawings. The blanket shall consist of machine-produced mat of curled wood excelsior or coconut fiber with consistent thickness and the fibers evenly distributed over the entire area of the blanket. The top of the blanket shall be covered with a biodegradable synthetic mesh. The mesh shall be attached to the curled wood excelsior or coconut fiber with photodegradable synthetic yarn. B. The Contractor shall place the curled wood or coconut fiber channel and slope SSB where directed immediately after the ditch has been properly graded and prepared,fertilized, and seeded. The mesh shall be on top with the fibers in contact with the soil. 32135-002102276V::5/7/2014 02276-7 GAC Upgrades for the Crozet and Scottsville WTPs C. The Contractor will immediately repair or replace section of blanket which is not functioning properly or has been damaged in any way until a stable growth of grass has been established. D. Blanket shall be American Excelsior Curlex II, North American Green C125,Contech EFB4 or equal matting with a minimum shear stress value of 2.0 lb./ft.2. 2.09 SYNTHETIC SOIL STABILIZATION MATTING (SSM) A. The Contractor shall place synthetic channel and slope SSM in channel or on slope as shown on the Drawings. The mat shall consist of entangled nylon, polypropylene or polyester monofilaments mechanically joined at their intersections forming a three dimensional structure. The mat shall be crush-resistant, pliable, water-permeable, and highly resistant to chemical and environmental degradation. B. The Contractor shall place the synthetic SSM where directed immediately after the channel or slope has been properly graded and prepared. C. After the SSM has been placed,the area shall be properly fertilized and seeded as specified allowing the fertilizer and seeds to drop through the net. D. The Contractor will immediately repair or replace section of SSM which is not functioning properly or has been damaged in any way until a stable growth of grass has been established. E. Synthetic SSM shall be Enkamat 7020 as manufactured by Colband Geosynthetics, Synthetic Industries Landlock Erosion Mat TRM 1060,TH8 as manufactured by TC Mirifi,or equal matting with a minimum shear stress value of 5.0 Ib./ft.2. 2.10 TEMPORARY GRAVEL CONSTRUCTION ENTRANCES A. Temporary gravel construction entrances shall be constructed as shown on the Drawings and as specified herein. Temporary gravel construction entrances shall be maintained in accordance with Part 3 of this Section, and Section 3.02 of the VESCH,to the satisfaction of the Engineer until the site has been stabilized. The cost of temporary gravel construction entrances shall include the gravel, truck wash racks and washwater, etc. and all maintenance activities required. 2.11 TEMPORARY SOIL STABILIZER A. The temporary agent for soil erosion control shall consist of an especially prepared highly concentrated powder which,when mixed with water,forms a thick liquid such as"Enviroseal 2001"by Enviroseal Corporation, "Terra Control"by Quattro Environmental, Inc.,or"CHEM- CRETE ECO-110" by International CHEM-CRETE Corporation, and having no growth or germination inhibiting factors. The agent shall be used for hydroseeding grass seed in combination with other approved amendments resulting in a highly viscous slurry which, when sprayed directly on the soil, forms a gelatinous crust. 32135-002102276V::5/7/2014 02276-8 GAC Upgrades for the Crozet and Scottsville WTPs PART 3 -- EXECUTION 3.01 INSTALLATION AND MAINTENANCE A. Erosion and sedimentation control devices shall be established prior to the clearing operations in a given area. Where such practice is not feasible, the erosion and sedimentation control device(s)shall be established immediately following completion of the clearing operation. B. The Contractor shall furnish the labor, materials and equipment required for routine maintenance of all erosion and sedimentation control devices. Maintenance shall be scheduled as required for a particular device to maintain the removal efficiency and intent of the device. Maintenance shall include but not be limited to 1)the removal and satisfactory disposal of trapped sediments from traps or silt barriers and 2)replacement of filter fabrics used for silt fences. Sediment removed from erosion and sedimentation control devices shall be disposed of in locations that will not result in off site sedimentation as acceptable to the Engineer, at no additional cost to the Owner. C. The Contractor shall provide temporary sedimentation traps at all locations shown on the Contract Drawings and for the settling of water pumped from the excavations or intercepted by drainage ditches for keeping water out of the excavations or to protect existing structures. The Contractor shall seed and mulch the earthen embankment with temporary or permanent vegetation immediately after installation. The Contractor shall remove trapped sediment from the basins when the design capacity has been reduced by 25% to maintain their effectiveness or as indicated by the Engineer. Sediment material removed from the basins shall be disposed by the Contractor in locations that will not result in off-site sedimentation as acceptable to the Engineer, at no additional cost to the Owner. 1. Inspect temporary sediment traps at least once every 14 days and within 48 hours after each runoff producing rainfall event. Remove sediment and restore the trap to its original dimensions when the sediment has accumulated to one-forth the design volume of the trap. Place the sediment that is removed in a designated disposal. area and replace the contaminated part of the aggregate facing. 2. Check the structure for damage from erosion or piping. Periodically check the depth of the spillway to ensure it is a minimum of 1.0 ft. below the low point of the embankment. Immediately fill settlement of the embankment to slightly above design grade. Riprap displaced from the spillway must be replaced immediately. 3. After all sediment-producing areas have been permanently stabilized and permission has been obtained from the plan approving authority, remove the structure and all unstable sediment. Smooth the area to blend with the adjoining areas and stabilize properly. D. The Contractor shall provide temporary diversions at all locations noted on the Contract Drawings. All temporary diversions shall outlet at a temporary sediment trap or other appropriate structure. 1. Inspect temporary diversions at least once every 14 days and within 48 hours after each runoff producing rainfall event. Immediately remove sediment form the flow area and repair the diversion ridge. Carefully check outlets and make timely repairs 32135-0021022761/::5/7/2014 02276-9 GAC Upgrades for the Crozet and Scottsville WTPs as needed. When the area protected is permanently stabilized and permission has been obtained from the plan approving authority, remove the ridge and the channel to blend with the natural ground level and appropriately stabilize it. E. Silt fence shall be erected as shown on the Drawings and specified herein. Silt fence shall be erected and maintained to the satisfaction of the Engineer until a vegetative ground cover has been established. Replacement of the filter fabric, if required by the Engineer,will be at the Contractor's expense. 1. Inspect silt fence at least once every 14 days and within 48 hours after each runoff producing rainfall event. Make required repairs immediately. 2. Should the fabric of a silt fence collapse, tear, decompose or become in-effective, replace it promptly. 3. Remove sediment deposits as necessary to provide adequate storage volume for the next rain and to reduce pressure on the fence. Take care to avoid undermining the fence during cleanout. 4. Remove all fencing materials and unstable sediment deposits and bring the area to grade and stabilize it after the contributing drainage area has been properly stabilized. Removal of silt fence shall be permitted only with the prior approval of the Engineer, or the local governing agency. F. Riprap shall be graded so that the smaller stones are uniformly distributed through the mass. The Contractor may place the stone by mechanical methods, augmented by hand placing 144.0, where necessary or ordered by the Engineer. The placed riprap shall form a properly graded, dense, neat layer of stone. The placed riprap shall have a minimum depth of 24 inches. Filter fabric shall be used under all riprap. The filter fabric must meet the requirements in Section 3.19 of the VESCH. G. Riprap and stone for erosion control shall be dumped and placed in such manner that the larger rock fragments are uniformly distributed throughout the rock mass and the smaller fragments fill the voids between the larger fragments. Rearranging of individual stones by equipment or by hand shall only be required to the extent necessary to secure the results specified above,to protect structures from damage when rock material is placed against the structures or to protect the underlying Filter Fabric from damage during installation. H. The Contractor shall provide Culvert Inlet Protection at all locations noted on the Contract Drawings. 1. Inspect Culvert Inlet Protection at least once every 14 days and within 48 hours after each runoff producing rainfall event. Remove sediment and restore the inlet protection to its original dimensions when the sediment has accumulated to one-half the design depth. Place the sediment that is removed in a designated disposal area and replace the contaminated part of the gravel facing. 2. Check the structure for damage from erosion or piping. Stone or riprap displaced from the berm must be replaced immediately. 32135-002\02276V:5/7/2014 02276-10 GAC Upgrades for the Crozet and Scottsville WTPs 3. After all sediment-producing areas have been permanently stabilized and permission has been obtained from the plan approving authority, remove the structure and all unstable sediment. Smooth the area to blend with the adjoining areas and stabilize properly. I. Engineer may direct the Contractor to place Straw with Net, Curled Wood or Coconut Fiber SSB's and Synthetic SSM's in permanent channels or on slopes at other locations not shown on Drawings. 1. All temporary and permanent channel linings shall be unrolled in the ditch in the direction of the flow of water. Temporary and permanent linings shall be installed in accordance with the requirements of Section 3.36 of the VESCH and per manufacturer's specifications. 2. During the establishment period, check grass,SSB and SSM-lined channels at least once every 14 days and within 48 hours after each runoff producing rainfall event. For grass-lined channel once grass is established,check periodically and after every runoff producing rainfall event. Immediately make repairs. It is particularly important to check the channel outlet and all road crossings for bank stability and evidence of piping and scour holes. Give special attention to the outlet and inlet sections and other points where concentrated flow enters. Remove all significant sediment accumulations to maintain the designed carrying capacity. Keep the grass in a healthy, vigorous condition at all times. J. The Contractor shall provide temporary slope drains at all location noted on the Contract Drawings, and at other locations as may be directed by the Engineer. 1. Inspect the temporary slope drain and supporting p ry diversion at least once every 14 days and after every runoff producing rainfall event and promptly make necessary repairs. When the protected area has been permanently stabilized, temporary measures may be removed, materials disposed of properly, and all disturbed areas stabilized appropriately. K. The Contractor shall provide temporary construction entrances at all locations noted on the Contract Drawings, and at all other locations as may be directed by the Engineer. 1. Maintain the gravel pad in a condition to prevent mud or sediment from leaving the construction site. This may require periodic topdressing with VDOT #1 course aggregate. Inspect each construction entrance at least once every 14 days and within 48 hours after each runoff producing rainfall event and clean out as necessary. Immediately remove all objectionable materials spilled, washed, or tracked onto public roadways. 2. Contractor shall provide wash rack and wash water for temporary construction entrances. The roadway under the temporary construction entrance shall be graded to drain into temporary sediment traps until construction activities cease and site around temporary construction entrance has been permanently stabilized. L. Permanent or temporary soil stabilization shall be applied to denuded areas within seven days after final grade is reached on any portion of the site. Temporary soil stabilization shall be applied within seven days to denuded areas that may not be at final grade but will remain 32135-002102276V::5/7/2014 02276-11 GAC Upgrades for the Crozet and Scottsville WTPs dormant(undisturbed)for longer than 30 days. Permanent stabilization shall be applied to areas that are to be left dormant for more than one year. Preparation of areas for permanent stabilization shall be performed in accordance with Section 2.32 of the VESCH. 1. Reseed and mulch temporary seeding areas where seedling emergence is poor, or where erosion occurs, as soon as possible. Do not mow. Protect from traffic as much as possible. 2. Generally, a stand of vegetation cannot be determined to be fully established until soil cover has been maintained for one full year from planting. Inspect seeded areas for failure and make necessary repairs and reseedings within the same season, if possible. 3. Reseeding — If a stand has inadequate cover, re-evaluate choice of plant materials and quantities of lime and fertilizer. Re-establish the stand after seedbed preparation or over-seed the stand. Consider seeding temporary, annual species if the time of year is not appropriate for permanent seeding. 4. If vegetation fails to grow, soil must be tested to determine if acidity or nutrient imbalance is responsible. 5. Fertilization — On the typical disturbed site, full establishment usually requires refertilization in the second growing season. Fine turf requires annual maintenance fertilization. Use soil tests if possible or follow the guidelines given for the specific seeding mixture. M. Additional Requirements 1. All storm sewer piping shall be blocked at the end of every Working day until the inlet is constructed above grade. 2. All streets around the construction area shall be scraped as necessary to prevent accumulation of dirt and debris. 3. The Contractor shall provide adequate means to prevent sediment from entering storm drains, curb inlets (curb inlet filter box), ditches, streams, or bodies of water downstream of any area disturbed by construction. Excavation materials shall be placed upstream of trench or other excavation to prevent sedimentation of offsite areas. In areas where a natural buffer area exists between the Work area and the closest stream or water course, this area shall not be disturbed. 4. The Engineer may direct the Contractor to place additional sediment and erosion control devices at other locations not shown on the Drawings. 5. The Contractor agrees to hold the Owner or any of its agents harmless from any and all liability, loss or damage that may arise out of a violation to the Erosion and Sediment Control Ordinance. 6. The Contractor shall monitor and take precautions to control dust, including, but not limited to, use of water or chemical dust palliative, limiting the number of vehicles allowed on site, minimizing the operating speed of all vehicles. 32135-002102276V:5/7/2014 02276-12 GAC Upgrades for the Crozet and Scottsville WTPs 3.02 INSPECTIONS AND MAINTENANCE A. The Contractor shall be responsible for the implementation of the Maintenance and Inspection Procedures as written by the Engineer. The implementation must comply with guidelines as set forth in General Virginia Pollutant Discharge Elimination System Permit Regulation for Discharges of Storm Water From Construction Activities(9 VAC 25-180)and VPDES General Permit No. VAR10. B. The Contractor shall designate a Qualified Person to perform inspections required by this Section 02276. The following areas are to be inspected and maintenance performed, if needed, at least once every 14 calendar days and within 48 hours of the end of runoff producing storm event. 1. Disturbed areas of the construction site that have not undergone final stabilization 2. Erosion and sediment control structures 3. All locations where vehicles enter or exit the site 4. Material storage and construction laydown areas that are exposed to precipitation and have not been finally stabilized C. When a Storm Water Pollution Prevention Plan (SWP3) is provided in the Contract Documents, the Qualified Person shall follow the practices inspection and maintenance requirements described in the SWP3. (See the Appendix for the SWP3, if applicable). All appropriate records required by the SWP3 shall be maintained on site. D. Immediate action will be taken to correct deficiencies to BMPs. The State reserves the right to stop all construction activities not related to maintaining BMPs until such deficiencies are repaired. E. In areas that have been finally stabilized, inspections and, if necessary, maintenance by Contractor will occur at least once per month for the duration of the contract or project, whichever is longer. F. During inspections the following will be observed and appropriate maintenance procedures taken: 1. The conformance to specifications and current condition of all erosion and sediment control structures. 2. The effectiveness and operational success of all erosion and sediment control measures. 3. The presence of sediments or other pollutants in storm water runoff at all runoff discharge points. 4. If reasonably accessible, the presence of sediments or other pollutants in receiving Waters. 32135-002102276V::5/7/2014 02276-13 GAC Upgrades for the Crozet and Scottsville WTPs 5. Evidence of off-site tracking at all locations where vehicles enter or exit the site. G. An inspection checklist is included in the SWP3. This checklist must be completed during each inspection, dated, and signed by the Qualified Person conducting the inspection. Completed inspection checklist shall be kept on-site with the Contract Documents and submitted to the Engineer on a monthly basis. The Contractor will repair deficiencies within 24 hours of inspection. 3.03 REMOVAL OF TEMPORARY SEDIMENT CONTROL STRUCTURES A. At such time that temporary erosion and control structures are no longer required under this item, the Contractor shall notify the Engineer and Albemarle County of its intent and schedule for the removal of the temporary structures,and obtain the Engineer's approval in writing prior to removal. Once the Contractor has received such written approval from the Engineer, the Contractor shall remove, as approved, the temporary structures and all sediments accumulated at the removed structure shall be returned upgrade. In areas where temporary control structures are removed,the site shall be left in a condition that will restore original drainage. Such areas shall be evenly graded and seeded as specified in Section 02910, Final Grading and Landscaping. 3.04 NOTICE OF TERMINATION A. When all construction activities have ceased,final stabilization has been implemented by the Contractor, and the site is in compliance with the VPDES permit, the Contractor, together with the Engineer shall submit a Notice of Termination. Nome - END OF SECTION - 32135-002102276V::5/7/2014 02276-14 GAC Upgrades for the Crozet and Scottsville WTPs SECTION 02500 SURFACE RESTORATION PART 1 -- GENERAL 1.01 THE REQUIREMENT A. Provide all labor, equipment, and materials necessary for final grading, topsoil placement, and miscellaneous site work not included under other Sections but required to complete the work as shown on the Drawings and specified herein. 1.02 RELATED WORK SPECIFIED ELSEWHERE A. Section 02200 - Earthwork B. Section 02276 - Erosion and Sedimentation Control C. Section 02910 - Final Grading and Landscaping PART 2 -- MATERIALS 2.01 TOPSOIL A. Topsoil shall meet the requirements of Section 02200 — Earthwork. PART 3 -- EXECUTION 3.01 FINAL GRADING A. Following approval of rough grading the subgrade shall be prepared as follows: 1. For riprap, bare soil 24 inches below finish grade or as directed by Engineer. 2. For topsoil, scarify 2-inches deep at 4 inches below finish grade. 3.02 TOPSOIL PLACEMENT A. Topsoil shall be placed over all areas disturbed during construction under any contract except those areas which will be paved, graveled or rip rapped. B. Topsoil shall be spread in place for lawn and road shoulder seed areas at a 4-inch consolidated depth and at a sufficient quantity for plant beds and backfill for shrubs and trees. C. Topsoil shall not be placed in a frozen or muddy condition. 32135-002102500:5/7/2014 02500-1 GAC Upgrades for the Crozet and Scottsville WTPs D. Final surface shall be hand or mechanically raked to an even finished surface to finish grade as shown on Drawings. E. All stones and roots over 4-inches and rubbish and other deleterious materials shall be removed and disposed of. - END OF SECTION - 14410., 32135-002102500:5/7/2014 02500-2 GAC Upgrades for the Crozet and Scottsville WTPs SECTION 02510 PAVING AND SURFACING PART 1 -- GENERAL 1.01 THE REQUIREMENT A. The Contractor shall furnish all labor,equipment and materials and perform all operations in connection with the construction of asphalt concrete pavement, asphalt concrete overlay, gravel roads,concrete curb and gutter, repair and reconstruction of existing asphalt concrete pavement, repair of existing gravel roads, and pavement markings complete as specified herein and as detailed on the Drawings. B. All new roads including the replacement of portions of the existing roads shall be to the limits, grades,thicknesses and types as shown on the Drawings. Patches for pipe crossings and areas damaged during the construction work shall be asphalt and/or gravel,depending upon the material encountered, unless otherwise indicated. 1.02 RELATED WORK SPECIFIED ELSEWHERE A. Requirements of related work are included in Division 1, Division 2 and Division 3 of these Specifications. 1.03 RELATED SECTIONS A. Section 02200 - Earthwork B. Section 03300 - Cast-In-Place Concrete 1.04 STANDARD SPECIFICATIONS A. Except as otherwise provided in the Specifications or on the plans, all work shall be in accordance with the Virginia Department of Transportation Road and Bridge Specifications except that any reference to "VDOT", "Department" or"Unit" shall mean the "Owner". B. Except with the approval of the Engineer, the placing of asphalt concrete surface paving shall be subject to the Seasonal and Weather Restrictions set forth in VDOT Specifications. PART 2 -- MATERIALS 2.01 SELECT FILL A. The Contractor shall place select fill as necessary to complete the embankments,shoulders, subgrade foundation and replacement for removed unsuitable material in accordance with VDOT Section 303, and Section 02200, Earthwork. 32135-002102510:5/7/2014 02510-1 GAC Upgrades for the Crozet and Scottsville WTPs 2.02 GRAVEL A. All work, including materials, associated with gravel shall be in accordance with VDOT Section 202, Crusher Run Aggregate, Size No. 26. 2.03 AGGREGATE BASE COURSE (ABC)AND SUBBASE COURSE A. All work, including materials,associated with Aggregate Base Course shall be in accordance with VDOT Sections 308, Subbase Course, and 309, Aggregate Base Course, except Articles 308.05 and 309.06 shall be deleted. Material shall be Type I Aggregate Base Material, Size 21A or 22, conforming with the applicable section of VDOT Section 208, Subbase and Aggregate Base Material. 2.04 ASPHALT CONCRETE PAVEMENT A. All work, including materials, associated with asphalt pavement shall be in accordance with VDOT Sections 315,Asphalt Concrete Pavement, and 211, Asphalt Concrete, except that Article 315.08 shall be deleted. Base Course shall be Superpave BM 25.0. Intermediate Course, if required, shall be Superpave IM 19.0A. Surface course shall be Superpave 8M 9.5A. B. The job mix formula shall be delivered to the Engineer at least two (2) weeks prior to beginning paving operations. 2.05 CONCRETE CURB AND GUTTERS A. Concrete shall be Class B in accordance with the requirements of Section 03300, Cast-In- Place Concrete, except that concrete shall be air-entrained to provide an air content of 6% ± 1.5%. B. Premolded expansion joint filler for expansion joints shall conform to ASTM D 1751 and shall be 1/2-inch thick, minimum. 2.06 ASPHALT TACK COAT A. All work, including materials, associated with asphalt tack coat shall be in accordance with Section 310, Tack Coat, of the VDOT Standard Specifications for Roads and Structures, except that Article 310.04 shall be deleted. 2.07 ASPHALT PRIME COAT A. All work including materials associated with Asphalt Prime Coat shall be in accordance with Section 311, Prime Coat, of the VDOT Specifications except that Article 311.04 shall be deleted. Application rates shall be 0.40 gallons of asphalt per square yard of pavement with a cover of#68 coarse aggregate at 30 pounds per square yard of pavement. 32935-002102510:5/7/2014 02510-2 GAC Upgrades for the Crozet and Scottsville WTPs PART 3 -- EXECUTION 3.01 EMBANKMENT A. The embankment shall be constructed in accordance with Section 02200, Earthwork. 3.02 SUBGRADE A. The subgrade, where shown on the Drawings, shall be compacted in accordance with Section 02200 - Earthwork. 3.03 BASE COURSE A. The finished base course of all paving shall be ABC and shall be of the thickness shown on the Drawings, formed true to crown and grade. Gravel roads, including repair to existing gravel roads shall be ABC and shall be of the thicknesses shown on the Drawings, formed true to crown and grade. No fill material except new ABC shall be placed on top of existing gravel. A. The finished base course of all paving shall be ABC and shall be of the thickness shown on the Drawings, formed true to crown and grade. Finished density shall be as specified in VDOT Section 309, Aggregate Base Course. 3.04 ASPHALT CONCRETE PAVEMENT A. Prior to placement of the asphalt concrete base course,the aggregate base course shall be inspected for damage or defects and repaired to the satisfaction of the Engineer. The surface of the base course shall be approved by the Engineer. B. The prime coat shall be applied to the surface of the approved base course as described in VDOT Section 311, Prime Coat. Equipment for applying the prime coat shall be power- oriented pressure spraying or distributing equipment suitable for the materials to be applied and approved by the Engineer. C. The asphalt concrete base shall be placed and compacted on the base course in layers not to exceed four inches. D. Prior to placement of the asphalt concrete surface course, the base/binder course shall be inspected for damage or defects and repaired to the satisfaction of the Engineer. E. The tack coat shall be applied to the surface of the approved base/binder course as described in VDOT Section 310. Equipment for applying the tack coat shall be power-oriented pressure spraying or distributing equipment suitable for the materials to be applied and approved by the Engineer. F. The Asphalt Concrete Surface Course shall be placed and compacted in accordance with requirements of VDOT Specifications. 32135-002102510:5/7/2014 02510-3 GAC Upgrades for the Crozet and Scottsville WTPs 3.05 CONCRETE CURB AND GUTTER A. The expansion joint filler for concrete curb and gutters shall be cut to conform with the cross section of the curb. Expansion joints shall be spaced at intervals of not more than 25-feet. Formed control joints shall be installed at intervals not exceeding 10 feet. Depth of joint shall be 1/3 the thickness. Curved forms shall be used where radii are indicated; straight segments shall not be permitted. Upon removal of the forms, exposed curb faces shall be immediately rubbed down to a smooth and uniform surface. No plastering shall be permitted. 3.06 UNDERGROUND UTILITY LINES A. Where an underground utility line is beneath the new roadway, the backfilling shall be carried out with special care,and the final consolidation shall be accomplished by a vibratory roller. Construction of the roadway over the trench shall be deferred as long as practicable. 3.07 JUNCTION WITH OTHER PAVING A. Where new asphalt concrete pavement abuts existing asphalt concrete pavement, the existing pavement shall be cut back to insure obtaining the specified compaction of the new pavement courses and interlocking adjoining courses. Existing subbase courses shall be cut back from the subgrade level of the new pavement on a one-on-one slope into the existing pavement, and the asphalt courses of the existing pavement shall be removed for an additional 6-inches back from the slope. The edge of the existing asphalt courses shall be saw cut straight and true. The faces between new and existing asphalt courses shall receive an application of tack coat. 3.08 ASPHALT CONCRETE OVERLAY A. Where asphalt concrete is proposed to be placed over an existing asphalt surface, the surfaces shall be thoroughly cleaned by power brooming and a tack coat shall be applied in accordance with VDOT Section 310, Tack Coat, prior to installing the overlay. The overlay shall be applied in accordance with Subsections 2.06 and 3.05 and Standard Details shown on the Drawings. - END OF SECTION - 32135-002102510:5/7/2014 02510-4 GAC Upgrades for the Crozet and Scottsville WTPs SECTION 02604 UTILITY STRUCTURES PART 1 -- GENERAL 1.01 THE REQUIREMENT A. Furnish all materials, labor, equipment,and tools required for the design,fabrication,delivery and installment of utility structures and appurtenances in accordance with the Drawings and as specified herein. 1.02 RELATED WORK SPECIFIED ELSEWHERE A. Section 02200— Earthwork B. Section 03200— Reinforcing Steel C. Section 03250— Concrete Accessories D. Section 03300—Cast-in-Place Concrete E. Section 03400— Precast Concrete F. Section 05540—Castings 1.03 REFERENCE SPECIFICATIONS, CODES AND STANDARDS A. Without limiting the generality of the other requirements of the specifications,all work herein shall conform to the applicable requirements of the following documents. All referenced specifications, codes, and standards refer to the most current issue available at the time of Bid. 1. ASTM C478 — Specification for Precast Reinforced Concrete Manhole Sections 2. ASTM C857 — Minimum Structural Design Loading for Underground Precast Concrete Utility Structures 3. ASTM C990 - Specifications for Joints in Concrete Pipe, Manholes,and Precast Box Sections Using Preformed Flexible Joint Sealants 1.04 SUBMITTALS A. Submit samples and/or Shop Drawings in accordance with Section 01300, Submittals. W B. In addition to items listed in Section 03400, Precast Concrete, Shop Drawings shall include, but not be limited to: 32135-002102604.5/7/2014 02604-1 GAC Upgrades for the Crozet and Scottsville WTPs 1. Complete layout and installation Drawings and schedules with clearly marked dimensions. 2. Material certificates on all piping materials. 3. Structural design calculations sealed by a P.E. registered in the Commonwealth of Virginia. Design calculations for precast manholes and vaults shall include confirmation structures adequately resist flotation when they are totally empty and subjected to groundwater full height of structure. 4. Results of leakage test PART 2 -- PRODUCTS 2.01 PRECAST MANHOLES, VAULTS, AND METER BOXES A. Precast utility structures shall be furnished with waterstops,sleeves and openings as noted on the Drawings. Box out for wall pipes shall conform accurately to the sizes and elevations of the adjoining pipes. Precast utility structures shall be watertight and conform to the requirements of ASTM C 478 and ASTM C857 with the following modifications there to: 1. Materials shall conform to Section 03400, Precast Concrete. 2. Manholes shall meet the following: a. Manhole section shall have an internal diameter of 4'-0", unless noted otherwise. b. Minimum manhole wall thicknesses shall be 5 inches for 4 foot and 5 foot diameter manholes,6 inches for 6 foot diameter manholes and 7 inches for 7 foot diameter manholes. c. Manholes and utility structures shall include ballast concrete and/or other means necessary to insure manholes resist flotation when empty and subjected to groundwater full height of structure. d. Precast manholes and utility structures shall be as manufactured by NC Products/Oldcastle, Tindall Products, or equal. 3. The date and name of manufacturer shall be marked inside each precast section. 4. No more than two lift holes may be cast or drilled in each section. 5. Dimensions shall be as shown on the Drawings. 6. Covers and frames shall be as specified in Section 2.13. 7. Mechanical Details such as piping, electrical, and other details shall be as shown on the Drawings. 32135-002102604:5/7/2014 02604-2 GAC Upgrades for the Crozet and Scottsville WTPs B. Joints between manhole and utility structures riser sections and at base slabs shall be groove type. New 2.02 JOINT SEALANT A. Joint sealant shall be a preformed flexible sealant conforming to the requirements of ASTM C990, paragraph 6.2, Butyl Rubber Sealant.Joint sealant shall be Pro-Stik Butyl Sealant by Press-Seal, Butyl-Nek Join Sealant by Henry,CS-102 Butyl Rubber Sealant for all Precast Structures by ConSeal, or equal. 2.03 COVERS AND FRAMES A. Covers and frames shall comply with Section 05540, Castings and shall be provided by the utility structure manufacturer. B. Manhole covers and frames shall meet the following requirements: 1. Locate so that there is ready access to the manhole steps 2. Clear opening shall be a minimum of 22 inches, unless otherwise indicated on the Drawings. 3. Watertight manhole frames and covers shall be suitable for 20 psi internal pressure and shall be Neenah Model R-1915, Type P or L or equal cast in place. 4. Non-watertight manhole covers shall be perforated and shall be Neenah Model R- 1668, or equal. 5. Storm drain grated inlet frames and grates shall be Neenah R-1878-B7G, East Jordan Iron Works V5660, or equal. 6. Curb inlet frames and grates shall be Neenah R-3067, East Jordan Iron Works EJ 7030, or equal, and shall include frame, grate, and hood. C. Vault covers shall have lifting handles and shall be bolted with stainless steel bolts complying with Section 05050, Metal Fastening. D. All frames and covers shall be given one shop coat of asphalt or coal tar varnish, unless otherwise specified. E. Frames and covers shall be identical throughout the Contract. 2.04 FLEXIBLE JOINT SEALER A. Flexible joint sealer shall be a rubber ring waterstop as manufactured by Fernco Joint Sealer Co., or equal. 2.05 EPDXY BONDING AGENT A. Epoxy bonding agent shall conform to Section 03250, Concrete Accessories. 32135-002102604:5/7/2014 02604-3 GAC Upgrades for the Crozet and Scottsville WTPs PART 3 -- EXECUTION 3.01 DESIGN CRITERIA A. Minimum structural design loading for underground precast concrete vaults shall be as indicated in ASTM C857, unless otherwise noted herein. Precast items subjected to vehicular traffic shall be designed for H-20 traffic loading. Other precast items shall be designed for a vertical live load of 300 psf. B. Walls of precast items shall be designed for a vertical surcharge of 100 psf. C. Precast manholes and vaults shall be designed to resist flotation when totally empty and subjected to groundwater full height of the manhole/vault. 3.02 FABRICATION AND CASTING A. Fabrication and casting shall conform to Section 03400, Precast Concrete, and to Section 03300, Cast-in-Place Concrete. B. All base sections designated to receive concrete ballast and all electrical manholes shall extend monolithically a minimum of 6 inches beyond the outside face of the wall for the entire periphery. All other utility structures shall have a standard base. C. Utility structures built around existing pipe shall have a cast-in-place base slab. 3.03 HANDLING, TRANSPORTING, AND STORING A. Handling,transporting and storing of precast items shall comply with Section 03400, Precast Concrete. 3.04 INSTALLATION A. Installation shall conform with Section 03400, Precast Concrete and with the manufacturer's recommendations or to Section 03300, Cast-in-Place Concrete. B. Frames and covers or grates shall be set so that tops are at elevations indicated on the Drawings or flush with finished grade where no elevation is indicated. C. Joints between riser sections shall be sealed with joint sealant. D. All openings in utility structures shall have flexible rubber sleeves sized to fit the connecting pipe and installed to provide watertight joints in accordance with the manufacturer's recommendations. The interior of the sleeve shall be filled with Class B concrete. E. Openings that are too large for flexible rubber sleeves shall utilize rubber bladder seals which are expanded by water injected using a pressure pump. F. All units shall be installed plumb and level. 32135-002102604:5/7/2014 02604-4 GAC Upgrades for the Crozet and Scottsville WTPs G. All lift holes and joints shall be filled with non-shrink grout conforming to Section 03600, grout inside and out. H. The manhole frames shall be set to their required elevations either with grade rings or with two or three courses of brick masonry laid around the top of the upper wall section. Such brick work shall be given a 1-inch mortar coat on the inside and out. I. Concrete ballast shall be placed so that it bears directly on the utility structure base against the outer wall monolithically encircling the structure for the full height indicated on the Drawings. Additional ballast may be required where the depth or elevation of the structure varies from the Drawings. J. Brick or Concrete Block Brick or concrete block shall be laid with broken joints and all horizontal and vertical joints filled with cement-sand mortar. Outside of walls shall be plastered with a minimum 1-inch thick coat of cement-sand mortar troweled smooth. K. Connection to Existing Pipe 1. Verify the diameter and invert elevation of existing pipe to be connected to new utility structures prior to beginning work on the structures. 2. Provide adequate protection to prevent damage to the existing pipe. 3. Provide adequate means for plugging and/or transferring the existing flow in the pipe to allow for the construction of inverts and grouting. 4. Cut off the existing pipe sufficiently for connection to the new structure and remove. 5. Thoroughly clean all foreign matter and coat the pipe surface with epoxy adhesive where the pipe joins the new structure. 6. Install a flexible joint sealer around the pipe. 7. Grout inside and outside of wall penetration with nonshrink grout. L. Backfill structures in accordance with Section 02200, Earthwork. M. Clean all structures of any accumulation of silt,debris, or foreign matter and keep clean until final acceptance of the work. N. Excavation shall conform to Section 02200, Earthwork. O. Structure bases shall bear on a minimum of 8 inches of compacted stone unless otherwise indicated on the Drawings. P. Channel Inverts 1. Inverts shall be placed using Class B concrete with forms sufficient to provide a smooth half-round shape as shown on the Drawings. Manhole bases employing full depth precast inverts are acceptable. 32135-002102604:5/7/2014 02604-5 GAC Upgrades for the Crozet and Scottsville WTPs 2. Where the slope of the line does not change through a manhole, a constant slope shall be maintained in the invert. Where slope changes occur within a given manhole, the transition shall be smooth and shall occur at the approximate center of the manhole. 3. Inverts shown on the Drawings are taken at the center of the manhole unless otherwise noted. 3.05 ADJUSTMENTS TO EXISTING UTILITY STRUCTURES A. Adjust structures as indicated on the Drawings using concrete or cast iron adjustment rings by approved methods. B. Clean covers and inlet castings of all foreign material and paint with one coat of coal tar epoxy. 3.06 ADJUSTING COLLARS AND FINAL ADJUSTMENTS A. Adjusting collars shall be as shown on the Drawings. Final adjustments shall be made so that the manhole ring and cover will be smooth and flush with the finished grade of the adjacent surface, or as otherwise indicated on the Drawings for manholes shown above grade. 3.07 FLUSHING AND TESTING A. Obstruction - After backfilling, all sewers shall be inspected for obstructions and shall be flushed with water. Flushing shall be a minimum velocity of 2.5 feet per second for duration acceptable to the Engineer. Flushing shall remove all dirt, stones, pieces of wood and other debris which accumulated in the sewer during construction. The Contractor shall provide a means acceptable to the Engineer for removal of debris flushed from each section of sewer. If after flushing, any obstructions remain, they shall be removed at the Contractor's expense. B. Visual Inspection - Sewer lines shall be visually inspected from every manhole by use of mirrors, television cameras, or other devices for visual inspection, and the lines shall all exhibit a fully circular pattern when viewed from one manhole to the next. Lines which do not exhibit a true line and grade or have structural defects shall be corrected to meet these qualifications. C. Leakage-Sewers shall be tested for leakage. The program of testing shall fit the conditions as mutually determined by the Engineer and the Contractor. The Contractor shall take all necessary precautions to prevent any joints from drawing while the sewers or their appurtenances are being tested. The Contractor shall, at his own expense, correct any excess leakage and repair any damage to the pipe and their appurtenances, or to any structures resulting from or caused by these tests. D. Leakage Test Procedure-Each section of sewer shall be tested by closing the lower end of the sewer to be tested and the inlet sewer of the upper manhole with stoppers and filling the pipe and manhole with water to a point 6 feet above the crown of the open sewer in the upper manhole, or, if ground water is present, 6 feet above the sections average adjacent ground water level as indicated by a monitor well installed adjacent to each manhole. The 32135-002102604:5/7/2014 02604-6 GAC Upgrades for the Crozet and Scottsville WTPs line shall be filled with water prior to testing and allowed to stand until the pipe has reached its maximum absorption, but not less than two (2) hours. After maximum absorption has been reached, the head shall be re-established and tested for at least six (6) hours maintaining the head specified above by measured additions of water. The sum of these additions shall be the leakage for the test period. If ground water is present to a height of at least 6 feet above the crown of the sewer at the upper end of the pipe section to be tested, the leakage test may be made by measuring the rate of infiltration using a suitable weir or other measuring device approved by the Engineer. Whether the test is made by infiltration or exfiltration,the allowable leakage shall not exceed 100 gallons per day per inch of diameter per mile of sewer being tested. Where the actual leakage exceeds the allowable, the Contractor shall discover the cause and correct it before the sewer will be accepted. For the purpose of this subsection, a section of sewer is defined as that length of sewer between successive manholes or special structures or stubouts for future connections. E. Low Pressure Compressed Air Test - If the leakage cannot be located by infiltration or exfiltration testing, this type test may be used. The pipeline shall be considered acceptable, when tested at an average pressure of 3.0 psi greater than the average back pressure of any groundwater that may submerge the pipe, if the section under test does not lose air at a rate greater than 0.0030 cfm per sq. ft. of internal pipe surface. F. Deflection Test-No sooner than thirty(30)days after final backfill installation,each section of PVC pipe shall be checked for vertical deflection using an electronic deflecto-meter or a rigid "Go-No-Go" device. Vertical deflection shall not exceed five (5) percent of the inside pipe diameter for PVC pipe. Where the actual deflection exceeds the allowable, the Contractor shall discover the cause and correct it before the pipe will be acceptable. For the purpose of this subsection, a section of sewer is defined as that length of sewer between successive manholes or special structures or stubouts for future connections. G. Cost of Testing and Repairs-Any and all work necessary to bring the line into conformance with the infiltration and deflection specifications shall be performed by the Contractor at no extra cost to the Owner. All apparent sources of infiltration and excessive deflection shall be repaired by the Contractor. The Contractor shall provide all water, plugs, hoses, pumps, equipment, etc. necessary for the proper flushing and testing of the sewers. - END OF SECTION - 32135-002102604:5/7/2014 02604-7 GAC Upgrades for the Crozet and Scottsville WTPs [THIS PAGE INTENTIONALLY LEFT BLANK] SECTION 02831 STEEL FENCING PART 1 -- GENERAL 1.01 THE REQUIREMENT A. The Contractor shall furnish and install steel fencing, posts, gates,etc.,where shown on the Drawings and in compliance with these Specifications. B. Fencing shall be of the chain link type topped with barbed wire. The 6-foot high fabric shall clear the final grade by 3 inches, and shall be topped with three strands of barbed wire. The barbed wire shall be angled outward at the top. All components which are to be galvanized shall be hot dipped galvanized, coating to be 1.8 ounces per square foot of surface. Alternate coatings which employ a zinc coating of less than 1.8 ounces per square foot are not acceptable. 1.02 RELATED WORK SPECIFIED ELSEWHERE A. Section 03300 - Cast-in-Place Concrete. 1.03 SUBMITTALS A. Shop Drawings shall be furnished in accordance with Section 01300, Submittals. PART 2 -- PRODUCTS 2.01 CHAIN LINK FABRIC A. Fabric shall be 9 gauge aluminum coated wire woven in a 2-inch diamond mesh conforming to ASTM A491. Top and bottom selvage to have a barbed finish. Minimum weight of coating shall be 0.40 ounce per square foot of wire surface. The coated wire shall have a minimum tensile strength of 80,000 lbs. per square inch. B. Install fabric 3 inches above ground level. Fence shall be stretched tight and securely fastened to posts at points spaced 12 inches apart maximum. 2.02 POSTS A. Posts and rails shall be galvanized standard weight pipe conforming to the requirements of ASTM F1083. W 1. Line Posts: Line posts shall be Schedule 40, 2-3/8 inch O.D. galvanized pipe with minimum bending strength of 201 pounds under a 6-foot cantilever load. Line posts shall be spaced at a maximum 10-foot O.C. 32135-002102831:5/7/2014 02831-1 GAC Upgrades for the Crozet and Scottsville WTPs 2. Terminal Posts: All end, corner, intermediate, and pull posts and gate leaves 6'0" wide and less shall be 2-7/8 inch O.D. galvanized Schedule 40 pipe with minimum bending strength of 381 pounds on 6-foot cantilever load. Gate posts for gate leaves shall be Schedule 40 pipe complying with ASTM F1083 of diameters as follows: Gate Leaf Width Pipe O.D. Weight per Ft. 0' to 6' 2-7/8" 5.79 lbs. Over 6' to 13' 4" 9.1 lbs. Over 13' to 18' 6-5/8" 18.97 lbs. Over 18' 8-5/8" 24.7Ibs. 2.03 TENSION WIRE A. Top and bottom tension wire shall be No. 7 gauge aluminum coated steel wire. Fabric shall be securely tied to tension wire at intervals not to exceed 24-inches. 2.04 POST TOPS AND BARBED WIRE SUPPORTS A. Gate,end, corner and line post tops shall be malleable iron or pressed steel and shall be hot dipped galvanized conforming to ASTM A153. B. Extension arms for supporting the three(3)strands of barbed wire for line posts shall be of pressed steel with malleable iron base, or solid aluminum alloy castings. C. Angles for line post extension arms shall be approximately 45 degrees from the vertical and the top slot for barbed wire shall be a minimum of 12 inches above the fabric and a minimum of 10 inches from the fence line. 2.05 BARBED WIRE A. Barbed wire shall consist of three strands of 12-1/2 gauge aluminum coated steel wire with 4-point barbs of 14 gauge aluminum wire spaced 5 inches apart,conforming to ASTM A585. B. Additional strands of barbed wire shall be added beneath the chain link fabric at all ditch crossings to maintain the security of the fence installation. 2.06 BRACES AND TOP RAILS A. Braces and top rails (where shown on the Drawings)shall be 1.66-inch O.D., Schedule 40 galvanized pipe with minimum vertical bending strength of 202 pounds on 10-foot span. B. Top rails shall be continuous and shall pass through the post tops. The coupling used to join the top rail lengths shall allow for expansion. Brace rails shall be provided at all terminal posts, located between the top and grade lines and extend from the terminal post to the first adjacent post. Braces shall be securely fastened at both ends. Brace ends for receiving brace rails shall be malleable iron or castings of 356.0(formerly SG70A)alloy, or equivalent of ASTM B26 or 8108. C. Truss and stretcher bands shall be 1/8-inch x 7/8-inch pressed steel, supplied with carriage bolts and nuts. Bolts shall be 5/16-inch by 1 1/4-inch. Truss rods shall be 3/8-inch nominal diameter. 32135-002102831:5/7/2014 02831-2 GAC Upgrades for the Crozet and Scottsville WTPs 2.07 FABRIC TIES A. Wire ties shall be preformed 0.148-inch diameter(9 gauge)aluminum. Flat band type ties shall be 1100-H18 or 3003-H14, .064-inch thick by 1/2-inch wide. B. Hog rings for attaching tension wire to fabric shall be 0.105-inch diameter,Alloy 1100-H14. 2.08 GATES A. Gate frames shall be made of 2-inch O.D. ASTM F1083 pipe, 2.72 lbs. per foot hot dipped galvanized. Fabric shall match fence. Gate frames shall be welded or assembled with riveted corner castings. Gate frames shall be equipped with 3/8-inch diameter adjustable truss bars. Hinges shall be ball and socket. B. Gate shall be equipped with positive latching device with provision for padlocking. Personnel gates shall be minimum 36-inch clear opening. 2.09 SLIDING GATE A. Sliding gates shall be cantilever type of the same height as adjacent fence. Gate shall be constructed of 2-1/2-inch O.D. Schedule 40 pipe 2-inch O.D. braces. Unit shall be similar in construction to swing gates. B. The main entrance gate shall be a double slide cantilever type gate with electric gate operators and vehicle detector loops for automatic operation. C. The truck entrance gate shall be a single cantilever type gate with electric gate operator and vehicle detector loop for closing operation. D. Gate Operators shall be heavy duty rated for high frequency commercial installation. Motors shall be 1 HP minimum, 480V, 3-phase. E. Card Reader shall be provided under Section 11050, Access Security System. 1. Intercom shall provide full two way communication between the gate and the Control Building control room and reception room. Intercom speaker at the gate shall be pedestal mounted adjacent to the card reader. Intercom speaker in the control room shall be wall-mounted adjacent to remote push button for gate operation. Intercom speaker and remote push button in control room shall be mounted in control console by distributed control system contractor. 2. Operation of the gate shall be as follows: a. Entrance - A driver or pedestrian can open the gate from the card reader device. The gate shall also be opened manually from the remote push button located in the control room. Should the gate encounter an obstruction during the closing cycle, the gate shall automatically reverse to the open position and the timer reset to full cycle. Auxiliary contacts shall be provided as required to receive gate open command signals from the loop detectors, card reader system, or the remote push buttons. 32135-002102831:5/7/2014 02831-3 GAC Upgrades for the Crozet and Scottsville WTPs b. Exit — The gate shall remain open until manually closed via remote pushbutton in the control room. 3. The gate shall be furnished complete with all operating controls by the fence supplier. Loop detectors shall be installed as directed by the Engineer including interconnecting wiring to the gate operating controls. Power control and intercom wiring shall be furnished and installed to provide a complete operational system. 4. Gate operator system shall be as manufactured by Customline, Inc.; Crusader Division of McKinney Electronics, or equal. PART 3 -- EXECUTION 3.01 INSTALLATION A. All line posts shall be spaced equidistant in the fence line on a maximum of 10-foot centers. Posts shall be set plumb in concrete bases as detailed on Drawings. The top of the posts shall be brought to a smooth grade line. The wire fence shall be set accurately to line and grade and shall be plumb. B. End, corner, pull or intermediate posts shall be placed in the following locations: corners; changes in direction;abrupt changes in grade; intervals no greater than 500 feet in the fence line. Each end or gate post shall have one brace assembly and each corner or intermediate post shall have two brace assemblies. C. Horizontal braces shall be provided at all terminal posts, corner posts, and intermediate posts between top rail and ground and shall extend from the above-mentioned posts to the first adjacent line posts. Braces shall be securely fastened to the line posts by brace ends and brace bands and to the terminal posts by approved rail end connectors. Diagonal brace rods shall be trussed from the brace end on the line post back to the terminal post, corner post or intermediate post and fastened to it by an approved connector. 3.02 POST FOUNDATIONS A. Post holes shall be in true alignment and of sufficient size to provide a permanent foundation of concrete. Holes shall be well centered on the posts. A minimum diameter of 12 inches shall be required for all posts. B. Post foundations shall be carefully rodded or tamped into place. The top of concrete shall extend 2 inches above ground line and shall be neatly troweled and leveled up from edges to the posts so as to have a pitch outward in all directions. C. No materials shall be installed on the posts, nor shall any load be applied to the posts within 3 days after the individual post foundation is completed. D. All concrete shall be Class"B"in conformance with Section 03300, Cast-in-Place Concrete. 3.03 RESETTING OF EXISTING FENCE 32135-002102831:5/7/2014 02831-4 GAC Upgrades for the Crozet and Scottsville WTPs A. Where shown on the Drawings that resetting of existing fence is required, the fence, after resetting, shall be in a condition that is equal to or better than before the fence was removed. B. The Contractor shall replace any of the fence components which have been unnecessarily damaged by him. 3.04 PADLOCK AND KEYS A. One solid brass padlock shall be furnished with each gate. Padlocks shall be master keyed to the system specified under Section 08710, Finish Hardware. 3.05 TEMPORARY FENCING A. The Contractor shall furnish and install all temporary fencing and appurtenances as shown on the Drawings or as required during construction to adequately secure the site prior to installation of the permanent fence. - END OF SECTION - 141,0, ;ems 32135-002102831:5/7/2014 02831-5 GAC Upgrades for the Crozet and Scottsville WTPs [THIS PAGE INTENTIONALLY LEFT BLANK]. SECTION 02910 FINAL GRADING AND LANDSCAPING PART 1 -- GENERAL 1.01 THE REQUIREMENT A. Furnish all labor, equipment, and materials necessary for final grading,topsoiling, seeding, and miscellaneous site work not included under other Sections, but required to complete the work as shown on the Drawings and specified herein. Under this Section, all areas of the project site disturbed by excavation, materials storage, temporary roads, etc., shall be reseeded as specified herein. 1.02 RELATED WORK SPECIFIED ELSEWHERE A. Section 02276 - Erosion and Sedimentation Control. B. Section 02500 - Surface Restoration. 1.03 SUBMITTALS A. Submit the following in accordance with Section 01300, Submittals. 1. Product Data 2. Certification of all materials 3. Three (3)copies of composition and germination certification and of test results for grass seed. PART 2 -- PRODUCTS 2.01 CONTRACTOR'S RESPONSIBILITIES A. Furnish and submit certification for the materials used as specified in the General Conditions, Division 1 and Division 2. 2.02 TOPSOIL A. Upon completion and Engineer's approval of the rough grading, the Contractor shall place the topsoil over all areas disturbed during construction under any contract except those areas which will be paved, graveled or rip rapped. Topsoil shall not be placed in a frozen or muddy condition and shall contain no toxic materials harmful to grass growth. Topsoil shall be as defined under Section 02200, Earthwork. 2.03 WATER A. Water shall be furnished to the Contractor by the Owner from existing facilities as directed by the Engineer. 32135-002102910V::5/7/2014 02910-1 GAC Upgrades for the Crozet and Scottsville WTPs B. The Contractor shall furnish all hoses and connections necessary to complete the landscaping work. 2.04 FERTILIZER A. Fertilizer shall be a complete commercial fertilizer with components derived from commercial sources. Fertilizer composition shall be determined from field soil sampling in appropriate number taken by the Contractor and analyzed by the Cooperative Extension Service Soil Testing Laboratory at VPI &SU or by a reputable commercial laboratory. Contractor shall furnish fertilizer in accordance with the recommendations of the testing laboratory and Section 3.32 of the Virginia Erosion and Sediment Control Handbook (VESCH). B. Fertilizer shall be delivered in standard size bags marked with the weight, analysis of contents, and the name of the manufacturer. Fertilizer shall be stored in weatherproof storage areas and in such a manner that its effectiveness will not be impaired. 2.05 LIME A. Contractor shall use an agricultural grade of limestone. Quantity shall be determined from field soil sampling in appropriate number taken by the Contractor and analyzed by the Cooperative Extension Service Soil Testing Laboratory at VPI & SU or by a reputable commercial laboratory. Contractor shall furnish lime in accordance with the recommendations of the testing laboratory and Section 3.32 of the VESCH. B. At least 50% shall pass a No. 200 U.S.S. mesh sieve. At least 90% shall pass a No. 100 U.S.S. mesh sieve and 100%shall pass a No. 10 U.S.S. mesh sieve. Total carbonates shall not be less than 80% or 44.8% Calcium Oxide equivalent. For the purpose of calculation, total carbonates shall be considered as Calcium Carbonate. 2.06 GRASS SEED A. Provide the kinds and amounts of seed to be seeded in areas disturbed by the construction work. All seed shall bear an official "Certified Seed" labeled and meet the requirements in Section 3.32 of the VESCH. All seed must have been certified by Virginia Crop Improvement Association within twelve (12) months immediately preceding the planting of such material on the job. B. The inoculant for treating legume seed mixture shall be a pure culture of nitrogen-fixing bacteria prepared specifically for the species. Inoculants shall not be used later than the date indicated on the container. Inoculants should be applied at two times the supplier's recommended rate on dry seedings and five times the recommended rate when included in hydroseeder slurry. The quality of the seed shall conform to the following: Minimum Minimum Maximum Seed Purity Germination Weed Seed Type (%) (%) (%) Kentucky 31 Tall Fescue 97 85 0.50 Perennial Ryegrass 98 90 0.50 32135-002102910V.:5/7/2014 02910-2 GAC Upgrades for the Crozet and Scottsville WTPs Minimum Minimum Maximum Seed Purity Germination Weed Seed Type (%) (%) (%) Kentucky Bluegrass 97 85 0.50 Annual Ryegrass 97 90 0.50 Weeping Lovegrass 98 87 0.50 German Millet 98 85 0.50 Cereal (Winter) Rye 98 85 0.50 Redtop 94 80 0.50 C. Seed mixtures to be used on the project shall be as follows: P - 190#/acre Kentucky 31 Tall Fescue, 5#/acre Perennial Ryegrass, 5#/acre Kentucky Bluegrass TW - 50#/acre Annual Ryegrass, 50#/acre Cereal (Winter) Rye TSP -- 100#/acre Annual Ryegrass TSU -- 50#/acre German Millet Note: PW - Permanent Seeding TW - Temporary Winter Seeding TSP - Temporary Spring Seeding TSU - Temporary Summer Seeding D. On cut and fill slopes 2:1 or steeper add 20#/acre of Weeping Lovegrass to the P seed mixture in the Spring and add 20#/acre Annual Ryegrass in Fall and Winter. 2.07 WOOD CELLULOSE FIBER MULCH A. For use in hydroseeding grass seed in combination with fertilizers and other approved additions, shall consist of especially prepared wood cellulose fibers such as "Conwed", "Silva-Fiber", or approved substitute, and have no growth or germination inhibiting factors, and be dyed green. B. The wood cellulose fiber shall have the additional characteristic of dispersing rapidly in water to form a homogeneous slurry and remain in such state when agitated in the hydraulic mulching unit, or adequate equal, with the specified materials. C. When applied, the wood cellulose fiber with additives will form an absorptive mat but not a plant inhibiting membrane,which will allow moisture, natural or mechanical,to percolate into underlying soil. D. Fiber mulch can be applied over top of newly seeded areas immediately after seed mixture is applied to soil bed or applied as part of the hydroseeded slurry containing the seed mixture. Anchored straw mulch shall be used in place of fiber mulch during hot and dry summer months and late fall. Fiber mulch can be used to tack (anchor) straw mulch. All fiber mulch shall adhere to requirements set forth in Section 3.35 of the VESCH. 32135-002102910V:5/712014 02910-3 GAC Upgrades for the Crozet and Scottsville WTPs E. The mulch shall be supplied, compressed in packages containing 50 pounds of material having an equilibrium air dry moisture content at time of manufacture of 12% plus or minus 2%. Wood cellulose fiber mulch shall be stored in a weatherproof storage area and in such a manner that effectiveness will not be impaired. 2.08 STRAW MULCH A. Straw used for mulch shall be wheat or oats. Straw shall be undamaged, air dry, threshed straw,free of undesirable weed seed. Straw mulch shall be spread by hand or machine and must be anchored or tacked down. Straw mulch is not required for seeded areas treated with a temporary soil stabilizer. All straw mulch shall adhere to requirements set forth in Section 3.35 of the VESCH. 2.09 TEMPORARY SOIL STABILIZER A. The temporary agent for soil erosion control shall consist of an especially prepared highly concentrated powder which,when mixed with water,forms a thick liquid such as"Enviroseal 2001"by Enviroseal Corporation,"Terra Control"by Quattro Environmental, Inc.,or"CHEM- CRETE ECO-110" by International CHEM-CRETE Corporation, and having no growth or germination inhibiting factors. The agent shall be used for hydroseeding grass seed in combination with other approved amendments resulting in a highly viscous slurry which, when sprayed directly on the soil, forms a gelatinous crust. 2.10 SOIL STABILIZATION BLANKET (SSB) A. The SSB shall be as specified in Section 02276 - Erosion and Sedimentation Control. 2.11 SYNTHETIC SOIL STABILIZATION MAT (SSM) A. The SSM shall be as specified in Section 02276 — Erosion and Sedimentation Control. 2.12 RIPRAP AND HERBICIDES A. Furnish and install sufficient quantity of landscape gravel or riprap to cover over the ground to a minimum 4-inch depth for gravel and 24-inch depth for riprap, unless otherwise noted, or indicated on the Drawings. Also furnish and apply an approved herbicide to the subgrade surface just prior to installing the landscape gravel or riprap. B. During placing,the stone shall be graded so that the smaller stones are uniformly distributed through the mass. The Contractor may place the stone by mechanical methods,augmented by hand placing where necessary or ordered by the Engineer. The placed riprap shall form a properly graded, dense, neat layer of stone. C. All topsoil and vegetative matter shall be removed from the subgrade surfaces prior to the application of the weed killer(herbicide)and to the placement of landscape gravel or riprap. Apply commercial-type herbicide as preemergence control of miscellaneous grasses and broadleaf weeds in granular or liquid form such as "Treflan", "Dymid", or approved substitute. Methods and rates of application shall be in strict compliance to manufacturer's directions and acceptable to the Engineer. 32135-002102910V::5/7/2014 02910-4 GAC Upgrades for the Crozet and Scottsville WTPs D. The herbicide selected shall be safe for use around ornamental plantings, have long-lasting weed control, and shall be resistant to leaching away under excessive rainfall. E. A second application of the herbicide shall be made on the surface of the landscape gravel or riprap sometime after the first six(6)months, but not later than twelve(12)months. Same methods and rates apply as specified previously. 2.13 TREE SHRUB PLANTING A. Provide trees and shrubs as shown on the Drawings and as specified in Section 3.37 of VESCH. PART 3 -- EXECUTION 3.01 GRADING A. After approval of the rough grading, the Contractor shall commence his preparations of the subgrade for the various major conditions of the work as follows: 1. Bare soil for riprap area at subgrade(24-inches below final grade, or as directed by the Engineer). 2. Topsoil for lawn and road shoulder seed area - scarify 2-inch depth of subgrade (4-inches below final grade) prior to placing topsoil. B. Final surface grading of the topsoiled, landscape graveled, and riprapped areas shall be mechanically raked or hand raked to an even finished surface alignment. 3.02 TOPSOIL A. Topsoil shall be spread in place for quantity required for lawn and road shoulder seed areas at 4-inch consolidated depth, and sufficient quantity for certain plant beds and backfill for shrubs and trees as specified. B. Topsoil shall be hospitable as a growth medium meeting all requirements as indicated by Sections 3.30 & 3.32 of VESCH. 3.03 HYDROSEEDING AND GRASS A. The Contractor shall grow a stand of grass on disturbed areas. The Contractor shall be responsible for the satisfactory growth of grass throughout the period of the one-year guarantee from Contract Closeout. B. The Contractor's work shall include the preparation of the topsoil and bare soil seed bed, application of fertilizer, limestone, mulching, inoculant, temporary soil stabilizer, watering, and other operations necessary to provide a satisfactory growth of sod at the end of the one-year maintenance period. 32135-002102910V::5/7/2014 02910-5 GAC Upgrades for the Crozet and Scottsville WTPs C. When hydraulic seeding method is used, include all additives and amendments required. A "Reinco", "Finn",or"Bowie"type hydromulcherwith adjustable nozzles and extension hoses, or approved substitute, shall be utilized. General capacity of tank should range from 500 to 2,500 gallons, or as approved by the Engineer. D. Hydraulic seeding shall be carried out in three steps. Step one shall consist of the application of lime. In step two the seed mixture shall be mixed with the fertilizer, wood cellulose fiber mulch, and any required inoculants and applied to the seed bed. The seed mixture can be applied as a separate process prior to the application of the slurry mixture. Step three shall consist of application of top dressing during the first spring or fall,whichever comes first, after step two. E. Top dressing shall consist of a commercial grade fertilizer plus Nitrogen or other analysis as may be recommended by soil testing. Types and application rates of seed mixtures shall be as shown in the Seeding Schedule. F. Ingredients for the mixture and steps should be dumped into a tank of water and thoroughly mixed to a homogeneous slurry and sprayed out under a minimum of 300-350 pounds pressure, in suitable proportions to accommodate the type and capacity of the hydraulic machine to be used. Applications shall be evenly sprayed over the ground surface. The Contractor shall free the topsoil of stones, roots, rubbish, and other deleterious materials and dispose of same off the site. The bare soil, except existing steep embankment area, shall be rough raked to remove stones, roots, and rubbish over 4-inches in size, and other deleterious materials and dispose of same off the site. G. No seeding should be undertaken in windy or unfavorable weather,when the ground is too wet to rake easily,when it is in a frozen condition,or too dry. Any bare spots shown in two to three weeks shall be recultivated, fertilized at half the rate, raked, seeded, and mulched again by mechanical or hand broadcast method acceptable to the Engineer. H. Areas that have been seeded with a temporary seed mixture shall be mowed to a height of less than 2-inches and scarified prior to seeding with the permanent seed mixture. I. The Contractor shall provide, at his own expense, protection for all seeded areas against trespassing and damage at all times until acceptance of the work. Slopes shall be protected from damage due to erosion, settlement,and other causes and shall be repaired promptly at the Contractor's expense. J. The Contractor shall water newly seeded areas of the lawn and road shoulder mix once a week until the grasses have germinated sufficiently to produce a healthy turf, or unless otherwise directed by the Engineer. Each watering shall provide three(3)gallons per square yard. The Contractor shall furnish all necessary hoses, sprinklers, and connections. K. The first and second cutting of the lawn grasses only shall be done by the Contractor. All subsequent cuttings will be done by the Owner's forces in a manner specified by the Contractor. 32135-002102910V::5/7/2014 02910-6 GAC Upgrades for the Crozet and Scottsville WTPs 3.04 SOIL STABILIZATION BLANKET (SSB) A. All channels and slopes indicated on the Drawings shall be lined with a SSB. The area to be covered shall be properly graded and hydroseeded before the blanket is applied. Installation shall be in accordance with Section 02276, Erosion and Sedimentation Control. 3.05 SOIL STABILIZATION MAT(SSM) A. All channels and slopes indicated on the Drawings shall be lined with a SSM. The area to be covered shall be properly graded before the mat is applied. Once the mat is placed and anchored, the area shall be seeded and mulched in accordance to this Specification and Section 3.36 of the VESCH. Installation shall be in accordance with Section 02276, Erosion and Sediment Control. 3.06 MAINTENANCE A. The Contractor shall be responsible for maintaining all seeded areas through the end of his warranty period. Maintenance shall include but not be limited to,annual fertilization,repair of seeded areas, irrigation(until permanent vegetation is fully established),and weed control. The Contractor shall provide, at his own expense, protection for all seeded areas against trespassing and damage at all times until acceptance of the work. Slopes shall be protected from damage due to erosion, settlement, and other causes and shall be repaired promptly at the Contractor's expense. B. Annual fertilization shall consist of an application of 500#/acre of 10-10-10 commercial grade fertilizer, or its equivalent and 60#/acre of nitrogen in early fall, or other analysis as may be determined by soil test. Annual fertilization shall be in addition to top dressing and shall be performed by the Contractor each fall season after planting until the work is substantially complete. C. Mowing shall be scheduled so as to maintain a minimum stand height of 4-inches or as directed by the Engineer. Stand height shall be allowed to reach 8 to 10-inches prior to mowing. D. All seeded areas shall be inspected on a regular basis and any necessary repairs or reseedings made within the planting season, if possible. If the stand should be over 60% damaged, it shall be re-established following the original seeding recommendations. E. Weed growth shall be maintained mechanically and/or with herbicides. When chemicals are used,the Contractor shall follow the current Virginia Agricultural Experiment Stations'weed control recommendations and adhere strictly to the instructions on the label of the herbicide. No herbicide shall be used without prior approval of the Engineer. 3.07 CLEANUP A. The Contractor shall remove from the site all subsoil excavated from his work and all other debris including, but not limited to, branches, paper, and rubbish in all landscape areas,and remove temporary barricades as the work proceeds. B. All areas shall be kept in a neat, orderly condition at all times. Prior to final acceptance, the Contractor shall clean up the entire landscaped area to the satisfaction of the Engineer. 32135-002102910V::5/7/2014 02910-7 GAC Upgrades for the Crozet and Scottsville WTPs 3.08 SEEDING SCHEDULE A. All seeding and mulching to be completed by the Contractor shall conform to Sections 3.32 and 3.35 of the VESCH. No permanent seeding shall be performed from May 1 -August 31 and November 1 —February 31. Temporary seed mixtures will be used during these times if seeding is necessary. Areas seeded with temporary seed mixtures shall be reseeded by the Contractor at no additional cost to the Owner with permanent seed as directed by the Engineer. B. 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