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HomeMy WebLinkAboutSDP200800128 Calculations 2008-08-11SIEG MAINTENANCE Erosion & Sediment Control Narrative Albemarle County, Virginia August 11, 2008 McKee CARSON LANDSCAPE ARCHITECTS - CONSULTING ENGINEERS - LAND PLANNERS 301 East High Street, Charlottesville, VA -22902 Tel: 434 - 979 -7522 Fax: 434-977-1194 www.mckeecarson.com TABLE OF CONTENTS Erosion and Sediment Control Plan Check List Erosion and Sediment Control Narrative Sediment Trap Design SIEG MAINTENANCE Erosion and Sediment Control Plan Check List CHECKLIST EROSION AND SEDIMENT CONTROL PLANS Plan No.: 8 I6 Plan Name: M AJIV FF N "C E NARRATIVE Project Description - Briefly describes the nature and purpose of the land disturbing activity, and the area (acres) to be disturbed. Existing Site Conditions - A description of the existing topography, vegetation and drainage. Adjacent Areas - A description of neighboring areas such as streams, lakes, residential areas, roads, etc., which might be affected by the land disturbance Off -Site Areas - Describe any off -site land disturbing activities that will occur including borrow sites, waste or surplus areas, etc.). Will any other areas be disturbed? Soils - A brief description of the soils on the site giving such information as soil name, mapping unit, erodibility, permeability, depth, texture and soil structure. Critical Areas - A description of areas on the site which have potentially serious erosion problems (e.g., steep slopes, channels, wet weather /underground springs, etc.). Erosion & Sediment Control Measures - A description of the methods which will be used to control erosion and sedimentation on the site. (Controls should meet the specifications in Chapter 3 of the Handbook.) Permanent Stabilization - A brief description, including specifications, of how the site will be stabilized after construction is completed. Stormwater Runoff Considerations - Will the development site cause an increase in peak runoff rates? Will the increase in runoff cause flooding or channel degradation downstream? Describe the strategy to control stormwater runoff. Calculations - Detailed calculations for the design of temporary sediment basins, permanent stormwater detention basins, diversions, channels, etc. Include calculations for pre- and post - development runoff. Maintenance - A schedule of regular inspections and repair of erosion and sediment control structures should be set forth. Checklist for Erosion and Sediment Control Plans Page 2 Minimum Standards - All applicable Minimum Standards must be addressed. The following minimum standards must be included in all narratives: 1.5(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. 1.5(4): Sediment basins and traps, perimeter dikes, sediment barriers and other measures intended to trap sediment shall be constructed as a first step in any land disturbing activity and shall be made functional before upslope land disturbance takes place. 1.5(5): Stabilization measures shall'be applied to earthen structures such as dams, dikes and diversions immediately after installation: 1.5(17): Where construction vehicle access routes intersect paved public roads, provisions shall be made to minimize the transport of sediment by (vehicular) tracking onto the paved surface. Where sediment is transported onto a public road surface, the road shall be cleaned thoroughly at the end of each day. Sediment shall be removed from the roads by shoveling or sweeping and transported to a sediment control disposal area. Street washing shall be allowed only after sediment is removed in this manner. This provision shall apply to individual subdivision lots as well as to larger land disturbing activities. 1.5(18): 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 disposition of temporary measures shall be permanently stabilized to prevent further erosion and sedimentation. Checklist for Erosion and Sediment Control Plans Page 3 SITE PLAN Vicinity Map - A small map locating the site in relation to the surrounding area. Include any landmarks which might assist in locating the site. Indicate North - The direction of north in relation to the site. Limits of Clearing & Grading - Areas which are to be cleared and graded. Existing Contours - The existing contours of the site. Final Contours - Changes to the existing contours, including final drainage patterns. Existing Ve etation - The existing tree lines, grassed areas, or unique vegetation. Soils - The boundaries of different soil types. Existing Drainage Patterns - The dividing lines and the direction of flow for the different drainage areas. Include the size (acreage) of each drainage area. Critical Erosion Areas - Areas with potentially serious erosion problems. (See Chapter 6 of the Handbook for criteria.) Site Development - Show all improvements such as buildings, parking lots, access roads, utility construction, etc. Location of Practices - The locations of erosion and sediment controls and stormwater management practices used on the site. Use the standard symbols and abbreviations in Chapter 3 of the Handbook.) Off -Site Areas - Identify any off -site land disturbing activities (e.g., borrow sites, waste areas, etc.). Show location of erosion controls. (Is there sufficient information to assure adequate protection and stabilization ?) Detail Drawings - Any structural practices used that are not referenced to the E &S Handbook or local handbooks should be explained and illustrated with detail drawings. Checklist for Erosion and Sediment Control Plans Page 4 MISCELLANEOUS INFORMATION Dust Control Construction Entrance - Wash rack if necessary. Note for the erosion control measures located on subdivision lots: "The developer shall reserve the right to install and maintain all erosion control measures required by this plan regardless of the sale of any lot." N. A- Waste Areas - Must comply with all waste area regulations (See Attachment #1). Nr A - Borrow Areas - Must comply with all borrow area regulations (See Attachment #2). Z!25% Slopes (Section 4.2.3 of Zoning Ordinance) 11/18/92 SIEG MAINTENANCE Erosion and Sediment Control Narrative 11 August, 2008 Project Description The SIEG Maintenance property is located in Albemarle County. The property is located on tax maps /parcels TMP 59 -23D, TMP 59 -23F and TMP 59 -23C1. The site is located in L -1 zoning area. The proposed development is an extension of the existing parking lot. The existing parking lot has 54 spaces and the proposed parking lot will have 96 parking spaces. The total disturbed area is approximately 1.98 acres. Existing Site Conditions The SIEG Maintenance site is mostly impervious with existing one -story brick and metal warehouse and parking lots. Most of the site has slope close to 5% with some critical slopes on west and north sides of the existing building and parking lots. The site has one drainage area and most of the runoff goes to existing culvert located on south -east corner of the property. Adjacent Areas The site includes a total of 2.92acres and located on U.S. Route 250. It is bordered along its western boundary by Northridge office (TMP 59 -23B), and along its eastern boundary by the Moser Clinic TMP 59 -23C). A CSX railway track is located on the northern side of the property. Off -Site Areas Required fill for this site must come from a borrow site with an approved E &S plan. Name and address of the owner must be provided to the county to verify at or before the pre construction meeting. If the fill site is still unknown at the time of construction, the contractor must use fill from an approved supplier. Soils Soil information is described in the soil map attached with Erosion and Sediment Control Details Plan Sheet 11). Critical Areas The critical areas of the project site have been shown on the Erosion and Sediment Control plan. Erosion and Sediment Control Measures Unless otherwise indicated, all erosion and sediment control practices will be constructed and maintained according to minimum standards and specifications of the Virginia Erosion and Sediment Control Handbook (1992). Temporary Construction Entrance - E &S Std. & Spec. 3.02 A Temporary Construction Entrance shall be installed where indicated. The Construction Entrance shall be paved with a wash rack. SIEG MAINTENANCE Erosion and Sediment Control Narrative 2. Construction Road Stabilization- E &S Std. & Spec. 3.03 Construction Road Stabilization shall be placed to stabilize the grading on the proposed entry driveway and parking lots. 3. Silt Fence with Wire Support- E &S Std. & Spec. 3.05 -1 Silt Fence with wire support shall be installed in a sequenced manner as shown on the plan. 4. Silt Fence Drop Inlet Protection- E &S Std. & Spec. 3.07 -1 Silt Fence Drop Inlet Protection shall be installed as shown on the plan. 5. Temporary Diversion Dike - E &S Std. & Spec. 3.09 Diversion Dikes shall be installed as shown on the plan to direct clean water away from the construction area. Diversion Dikes shall be stabilized by EC -2 matting wherever slope is grater than 2 %. 6. Temporary Right -of -Way Diversion- E &S Std. & Spec. 3.11 Right -of -Way Diversion shall be installed as shown on the plan to direct runoff from disturbed area towards the proposed sediment trap. 7. Temporary Sediment Trap E &S Std. & Spec. 3.13 Sediment Traps shall be installed as shown on the Erosion and Sediment Control plan and detail sheets. Outlet Protection - E &S Std. & Spec. 3.18 Outlet Protection shall be installed where shown on the plans. See attached calculations for dimensions. 9. Topsoiling - E &S Std. & Spec. 3.29 Topsoil will be stripped from areas to be graded and stockpiled for later use. Stockpile locations shall be located on -site and are to be stabilized with temporary vegetation. Selection of the seed mixture will depend on the time of year it is applied. Prior to land- disturbing activities, the contractor shall submit a supplementary E & S plan to the owner covering the off -site stockpile area which would have to be approved by the plan approving authority before any off -site activity commences. 10. Temporary Seeding: E &S Std. & Spec. 3.31 All areas temporary disturbed by construction (like diversion dike etc) will be stabilized with temporary seeding immediately following the conclusion of clearing operations. Unless otherwise specified, permanent seeding will be done with a seed mix approved by the Owner prior to application in accordance to E &S Std. and Spec. 3.31 of the 1992 Virginia Erosion and Sediment Control Handbook. 11. Permanent Seeding: E &S Std. & Spec. 3.32 All areas disturbed by construction will be stabilized with permanent seeding immediately following the conclusion of clearing operations. Unless otherwise specified, permanent seeding will be done with a seed mix approved by the Owner prior to application in accordance to E &S Std. and Spec. 3.32 of the 1992 Virginia Erosion and Sediment Control Handbook. SIEG MAINTENANCE Erosion and Sediment Control Narrative 12. Mulching: E &S Std. & Spec. 3.35 Areas which have been temporarily/ permanently seeded, diversion dikes, fill diversion should be mulched immediately following seeding. 13. Dust Control - E &S Std. & Spec. 3.39 Dust Control practices shall be employed to prevent surface and air movement of dust from exposed soil surfaces and reduce the presence of airborne substances which may be harmful or injurious to human health, welfare, or safety, or to animal or plant life. Permanent Stabilization 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 for longer than 30 days. Permanent stabilization shall be applied to areas that are to be left dormant for more than one year. 2. During construction of the project, soil stockpiles and borrow areas shall be stabilized or protected with sediment trapping measures. The applicant is responsible for the temporary protection and permanent stabilization of all soil stockpiles on site as well as borrows areas and soil intentionally transported from the project site. 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 is uniform, mature enough to survive and will inhibit erosion. 4. Sediment traps, perimeter dikes, sediment barriers and other measures intended to trap sediment shall be constructed as a first step in any land- disturbing activity and shall be made functional before upslope land disturbance takes place. 5. Stabilization measures shall be applied to earthen structures such as dikes and diversions immediately after installation. Minimum Standards Installation of all erosion and sediment control measures shall conform to the 1992 Virginia Erosion and Sediment Control Handbook. Critical measures required on this project are summarized below: 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 for longer than 30 days. Permanent stabilization shall be applied to areas that are to be left dormant for more than one year. SIEG MAINTENANCE Erosion and Sediment Control Narrative 2. During construction of the project, soil stockpiles and borrow areas shall be stabilized or protected with sediment trapping measures. The applicant is responsible for the temporary protection and permanent stabilization of all soil stockpiles on site as well as borrows areas and soil intentionally transported from the project site. 3. 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, is uniform, mature enough to survive and will inhibit erosion. 4. Sediment basins and traps, perimeter dikes, sediment barriers and other measures intended to trap sediment shall be constructed as a first step in any land- disturbing activity and shall be made functional before upslope land disturbance takes place. 5. Stabilization measures shall be applied to earthen structures such as dams, dikes and diversions immediately after installation. 6. Sediment traps shall be designed and constructed based upon the total drainage area to be served by the trap or basin. a. The minimum storage capacity of a sediment trap shall be 134 cubic yards per acre of drainage area and the trap shall only control drainage areas less than three acres. b. Surface runoff from disturbed areas that is comprised of flow from drainage areas greater than or equal to three acres shall be controlled by a sediment basin. The minimum storage capacity of a sediment basin shall be 134 cubic yards per acre of drainage area. The outfall system shall, at a minimum, maintain the structural integrity of the basin during a twenty - five year storm of 24 -hour duration. Runoff coefficients used in runoff calculations shall correspond to a bare earth condition or those conditions expected to exist while the sediment basin is utilized. 7. Cut and fill slopes shall be designed and constructed in a manner that will minimize erosion. Slopes that are found to be eroding excessively within one year of permanent stabilization shall be provided with additional slope stabilizing measures until the problem is corrected. 8. Concentrated runoff shall not flow down cut or fill slopes unless contained within an adequate temporary or permanent channel, flume or slope drain structure. 9. Whenever water seeps from a slope face, adequate drainage or other protection shall be provided. 10. All storm sewer inlets that are made operable during construction shall be protected so that sediment -laden water cannot enter the conveyance system without first being filtered or otherwise treated to remove sediment. 11. Before newly constructed stormwater conveyance channels or pipes are made operational, adequate outlet protection and any required temporary or permanent channel lining shall be installed in both the conveyance channel and receiving channel. SIEG MAINTENANCE Erosion and Sediment Control Narrative 12. When work in a live watercourse is performed, precautions shall be taken to minimize encroachment, control sediment transport and stabilize the work area to the greatest extent possible during construction. Nonerodible material shall be used for the construction of causeways and cofferdams. Earthen fill may be used for the structures if armored by nonerodible cover materials. 13. When a live watercourse must be crossed by construction vehicles more than twice in any six - month period, a temporary vehicular stream crossing constructed of nonerodible material shall be provided. 14. All applicable federal, state and local regulations pertaining to working in or crossing live watercourses shall be met. 15. The bed and banks of a watercourse shall be stabilized immediately after work in the watercourse is completed. 16. Underground utility lines shall be installed in accordance with the following standards in addition to other applicable criteria: a. No more than 500 linear feet of trench may be opened at one time. b. Excavated material shall be placed on the uphill side of trenches. Effluent from dewatering operations shall be filtered or passed through approved sediment trapping device, or both, and discharged in a manner that does not adversely affect flowing streams or off -site property. d. Material used for backfilling trenches shall be properly compacted in order to minimize erosion and promote stabilization. Restabilization shall be accomplished in accordance with these regulations. f. Applicable safety regulations shall be complied with. 17. Where construction vehicle access routes intersect paved or public roads, provisions shall be made to minimize the transport of sediment by vehicular tracking onto the paved surface. Where sediment is transported onto a paved or public road surface, the road surface shall be cleaned thoroughly at the end of each day. Sediment shall be removed from the roads by shoveling or sweeping and transported to a sediment control disposal area. Street washing shall be allowed only after sediment is removed in this manner. This provision shall apply to individual development lots as well as to larger land- disturbing activities. 18. 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 authority. Trapped sediment and the disturbed soil areas resulting from the disposition of temporary measures shall be permanently stabilized to prevent further erosion and sedimentation. SIEG MAINTENANCE Erosion and Sediment Control Narrative 19. Stormwater Runoff Consideration (MS -19) Properties and waterways downstream from development sites shall be protected from sediment deposition, erosion and damage due to increases in volume, velocity and peak flow rate of stormwater runoff for the stated frequency storm of 24 -hour duration in accordance with the following standards and criteria: a. Concentrated stormwater runoff leaving a development site shall be discharged directly into an adequate natural or man -made receiving channel, pipe or storm sewer system. For those sites where runoff is discharged into a pipe or pipe system, downstream stability analyses at the outfall of the pipe or pipe system shall be performed. b. Adequacy of all channels and pipes shall be verified in the following manner: 1) The applicant shall demonstrate that the total drainage area to the point of analysis within the channel is one hundred times greater than the contributing drainage area of the project in question; or 2) (a) Natural channels shall be analyzed by the use of a two -year storm to verify that stormwater will not overtop channel banks nor cause erosion of channel bed or banks; and b) All previously constructed man -made channels shall be analyzed by the use of a ten - year storm to verify that stormwater will not overtop its banks and by the use of a two -year storm to demonstrate that stormwater will not cause erosion of channel bed or banks; and c) Pipes and storm sewer systems shall be analyzed by the use of a ten -year storm to verify that stormwater will be contained within the pipe or system. c. If existing natural receiving channels or previously constructed man -made channels or pipes are not adequate, the applicant shall: 1) Improve the channel to a condition where a ten -year storm will not overtop the banks and a two -year storm will not cause erosion to the channel bed or banks; or 2) Improve the pipe or pipe system to a condition where the ten -year storm is contained within the appurtenances; or 3) Develop a site design that will not cause the pre - development peak runoff rate from a two -year storm to increase when runoff outfalls into a natural channel or will not cause the pre - development peak runoff rate from a ten -year storm to increase when runoff outfalls into a man -made channel; or 4) Provide a combination of channel improvement, storm water detention or other measures which is satisfactory to the plan- approving authority to prevent downstream erosion. d. The applicant shall provide evidence of permission to make the improvements. SIEG MAINTENANCE Erosion and Sediment Control Narrative e. All hydrologic analyses shall be based on the existing watershed characteristics and the ultimate development of the subject project. f. If the applicant chooses an option that includes storm water detention he shall obtain approval from the locality of a plan for maintenance of the detention facilities. The plan shall set forth the maintenance requirements of the facility and the person responsible for performing the maintenance. g. Outfall from a detention facility shall be discharged to a receiving channel, and energy dissipaters shall be placed at the outfall of all detention facilities as necessary to provide a stabilized transition from the facility to the receiving channel. h. All on -site channels must be verified to be adequate. i. Increased volumes of sheet flows that may cause erosion or sedimentation on adjacent property shall be diverted to a stable outlet, adequate channel, pipe or pipe system, or to a detention facility. j. In applying these storm water runoff criteria, individual lots or parcels in a residential, commercial or industrial development shall not be considered to be separate development projects. Instead, the development, as a whole, shall be considered to be a single development project. Hydrologic parameters that reflect the ultimate development condition shall be used in all engineering calculations. k. All measures used to protect properties and waterways shall be employed in a manner which minimizes impacts on the physical, chemical and biological integrity of rivers, streams and other waters of the state. General construction notes for Erosion and Sediment Control plans The plan approving authority must be notified one week prior to the pre - construction conference, one week prior to the commencement of land disturbing activity, and one week prior to the final inspection. 2. All erosion and sediment control measures will be constructed and maintained according to minimum standards and specifications of the Virginia Erosion and Sediment Control Handbook and Virginia Regulations VR 625 -02 -00 Erosion and Sediment Control Regulations. 3. All erosion and sediment control measures are to be placed prior to or as the first step in clearing. 4. A copy of the approved erosion and sediment control plan shall be maintained on the site at all times. Prior to commencing land disturbing activities in areas other than indicated on these plans including, but not limited to, off -site borrow or waste areas), the contractor shall submit a supplementary erosion control plan to the owner for review and approval by the plan approving authority. SIEG MAINTENANCE Erosion and Sediment Control Narrative 6. The contractor is responsible for installation of any additional erosion control measures necessary to prevent erosion and sedimentation as determined by the plan approving authority. 7. All disturbed areas are to drain to approved sediment control measures at all times during land disturbing activities and during site development until final stabilization is achieved. 8. During dewatering operations, water will be pumped into an approved filtering device. The contractor shall inspect all erosion control measures periodically and after each runoff producing rainfall event. Any necessary repairs or cleanup to maintain the effectiveness of the erosion control devices shall be made immediately. 10. All fill material to be taken from an approved, designated borrow area. 11. All waste materials shall be taken to an approved waste area. Earth fill shall be inert materials only, free of roots, stumps, wood, rubbish, and other debris. 12. Borrow or waste areas are to be reclaimed within 7 days of completion per Zoning Ordinance section 5.1.28. 13. All inert materials shall be transported in compliance with section 13 -301 of the Code of Albemarle. 14. Borrow, fill or waste activity involving industrial -type power equipment shall be limited to the hours of 7:OOam to 9:OOpm. 15. Borrow, fill or waste activity shall be conducted in a safe manner than maintains lateral support, or order to minimize any hazard to persons, physical damage to adjacent land and improvements, and damage to any public street because o slides, sinking, or collapse. 16. The developer shall reserve the right to install, maintain, remove or convert to permanent stormwater management facilities where applicable all erosion control measures required by this plan regardless of the sale of any lot, unit, building or other portion of the property. 17. Temporary stabilization shall be temporary seeding and mulching. Seeding is to be at 75 lbs /acre, and in the months of September to February to consist a 50/50 mix of Annual Ryegrass and Cereal Winter Rye, or in March and April to consist of Annual Rye, or May through August to consist of German Millet. Straw mulch is to be applied at 80lbs/ 100sf. Alternatives are subject to approved by the County erosion control inspector. 18. Permanent stabilization shall be lime and fertilizer, permanent seeding, and mulch. Agricultural grade limestone shall be applied at 90lbs/ 1000sf, incorporated into the top 4 -6 inches of soil. Fertilizer shall be applied at 1000lbs /acre and consist of a 10 -20 -10 nutrient mix. Permanent seeding shall be applied at 1801bs /acre and consist of 95% Kentucky 31 or Tall Fescue and 0 -5% Perennial Ryegrass or Kentucky Bluegrass. Straw mulch is to be applied at 801bs /100sf. Alternatives are subject to approved by the County erosion control inspector. SIEG MAINTENANCE Erosion and Sediment Control Narrative 19. Maintenance: All measures are to be inspected weekly and after each rainfall. Any damage or clogging to structural measures is to be repair immediately. Silt traps are to be cleaned when 50% of the wet storage volume is filled with sediment. All seeded areas are to be reseeded when necessary to achieve a good stand of grass. Silt fence and diversion dykes which are collecting sediment to half their height must be cleaned and repaired immediately. 20. All temporary erosion and sediment control measures are to be removed within 30 days of final site stabilization, when measures are no longer needed, subject to approval by the County erosion control inspector. Management Strategies Construction should be sequenced so that grading operations can begin and end as quickly as possible. 2. The job contractor shall be responsible for the installation and maintenance of all erosion and sediment control practices. 3. Sediment trapping measures shall be installed as a first step in grading and shall be seeded and mulched immediately following installation. 4. Areas which are not to be disturbed shall be clearly marked by flags, signs, etc. Soil stockpiles and borrow areas Topsoil will be stripped from areas to be graded and stockpiled for later use. Stockpile locations shall be located on -site and are to be stabilized with temporary vegetation. Selection of the seed mixture will depend on the time of year it is applied. Construction Schedule It is our understanding that site work construction will be beginning once final approvals have been received. Maintenance All erosion and sediment control measures will be checked weekly, after each runoff - producing rainfall event and repaired as necessary. Seeded areas will be checked regularly to ensure that a good stand is maintained. Reseeding and straw mulch will be applied as necessary. SIEG MAINTENANCE Sediment Trap Design ipany:clarsa:= 1) Enter Project No.: 2) Enter trap identification number: 3) Enter additional trap identification (e.g. centerline stationing): 4) Enter area draining into trap (AC) ( <3.0): storage required (CY): storage required (CF): wet storage required (CF): dry storage required (CF): 810 ST1 Upstream Base of Fill 1.45 194 5246 2623 2623 5) Enter depth of excavation (ft) ( < =4.0):2.00 6) Enter side slopes of excavated wet storage area (_:1):1.00 area of top of wet storage (1st try) (SF):1507 1st try width of wet storage (ft):19 1st try length of wet storage (ft):79 7) Enter a new value for width:35.00 8) Enter a new value for length:43.06 top area based on new width & length (SF):1507 bottom area (SF):1211 average area (bottom, top) (SF).1359 volume based on average area (CF).2718 volume required (CF):2623 okay?YES 9) Repeat steps (8) and (9) until volume requirement is exceeded and dry storage 11w => 2 10) Enter H(0), which is also D(2) (ft) (0.5 <= H(0) < =4.0): 11) Enter side slopes of dry storage volume (_:1): width of basin (ft): length of basin (ft): dry storage 11w: volume based on average area (CF): dry storage volume required (CF): okay? ST1 AREA =1.45 Ac. ELEVATION L W D Z BOTT 39 31 2.0 1.0 WET 43 35 1.5 2.0 DRY 49 41 WEIR 8.7 2.5 1.50 2.00 41 49 1.20 2639 2623 YES r............. Car$Qir : 1) Enter Project No.: 2) Enter trap identification number: 3) Enter additional trap identification (e.g. centerline stationing): 4) Enter area draining into trap (AC) ( <3.0): storage required (CY): storage required (CF): wet storage required (CF): dry storage required (CF): 810 ST2 Upstream Base of Fill 0.60 80 2171 1085 1085 5) Enter depth of excavation (ft) ( < =4.0):2.00 6) Enter side slopes of excavated wet storage area (_:1):1.00 area of top of wet storage (1 st try) (SF).1055 1st try width of wet storage (ft):19 1st try length of wet storage (ft):55 7) Enter a new value for width:64.00 8) Enter a new value for length:16.48 top area based on new width & length (SF):1055 bottom area (SF):749 average area (bottom, top) (SF).902 volume based on average area (CF):1804 volume required (CF):1085 okay?YES 9) Repeat steps (8) and (9) until volume requirement is exceeded and dry storage I/w => 2 10) Enter H(0), which is also D(2) (ft) (0.5 <= H(0) < =4.0): 11) Enter side slopes of dry storage volume (_:1): width of basin (ft): length of basin (ft): dry storage l /w: volume based on average area (CF): dry storage volume required (CF): okay? IMM - ST2 AREA =0.60 Ac. ELEVATION L W D Z BOTT 12 60 2.0 1.0 WET 16 64 1.0 3.0 DRY 22 70 WEIR 3.6 2.0 1.00 3.00 70 22 0.32 1314 1085 YES q, 9 C Z I i %Illfiv