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HomeMy WebLinkAboutWPO201400015 Assessment - Environmental 2014-02-25 EROSION AND SEDIMENT CONTROL PROJECT NARRATIVE AND STORMWATER MANAGEMENT REPORT FOR VERDANT LAWN RESIDENCE VERDANT LAWN LANE CHARLOTTESVILLE, VIRGINIA i,TH Op D r. i FEBRUARY 24, 2014 Lie. No. 051495 0 2/24/141 PREPARED BY: �y DRAPER ADEN ASSOCIATES S1ONAL 700 HARRIS STREET, SUITE E CHARLOTTESVILLE, VA 22903 DAA PROJECT No.C 13104C-01 =raw: Draper Aden Associates It,ngincering • Sur%cVing • En\irllnmental Ser\ices TABLE OF CONTENTS PART I: EROSION AND SEDIMENT CONTROL NARRATIVE 4 A. PROJECT DESCRIPTION 4 B. EXISTING SITE CONDITIONS 4 C. ADJACENT PROPERTY 4 D. PLANNED OFFSITE ACTIVITIES 5 E. SOILS 5 F. CRITICAL EROSION AREAS 5 G. EROSION AND SEDIMENT CONTROL MEASURES 6 H. STRUCTURAL PRACTICES 10 I. VEGETATIVE PRACTICES 11 J. PERMANENT STABILIZATION 12 K. CONSTRUCTION SCHEDULE 12 L. MAINTENANCE 13 PART II: STORMWATER MANAGEMENT REPORT 15 A. STORMWATER MANAGEMENT OVERVIEW 15 B. WATER QUALITY ANALYSIS 16 C. WATER QUANTITY ANALYSIS 16 APPENDICES APPENDIX A—Soil Survey Report E&S and SWM Narrative—Verdant Lawn Residence Page 2 of 15 Part 1: Erosion & Sediment Control Narrative A. PROJECT DESCRIPTION The project consists of the construction of an approximately 5,000 square foot(footprint) residence with a pool and associated driveway in Albemarle County, Virginia. The project will have a total disturbed area of approximately 9.6 acres. This includes the area for the house, driveway, grading and landscaping. There is approximately 23,500 square feet impervious area in the pre-developed condition and approximately 14,500 square feet of this area will be removed with the project. Construction will add approximately 39,650 square feet for a total impervious area of 48,650 square feet(1.12 acres). The project is anticipated to begin in the spring of 2014 and be completed by the summer of 2015 with construction lasting for approximately 12 to 15 months. B. EXISTING SITE CONDITIONS The site is located on Verdant Lawn Lane. The house will be constructed on a 143.8 acre farm known as Verdant Lawn. The farm currently has entrances off of Old Ballard Road and Ivy Road (Route 250)and includes driveways to the farm manager's house, a guest cottage, a farm center and a dairy barn. The parcel is zoned RA (Rural Areas). The property is generally hilly and slopes to water courses along three sides. The majority of the site is grazed fields with sporadic large trees. The location of the driveway and house is at the high point of the property (approximately elevation 610'). Slopes at the house are generally around 2-7% but fall off with slopes up to 3:1 in all directions.These are long slopes which sheet flow to several valleys as they leave the site and enter the adjacent water courses. Elevations along the property lines generally range from 470' to 500'. All runoff ends up in Ivy Creek which flows along the west and north sides of the property and continues to flow to the northeast. C. ADJACENT PROPERTY The property is bordered by Ivy Creek and additional rural zoned properties to the north and west, CSX Railroad and Ivy Road (US Route 250) to the south and a tributary to Ivy Creek and Old Ballard Road(State Route 677) to the east. The site of the house is surrounded by grazed fields. The house sits approximately 900' from Ivy Road, 1,100' from Ivy Creek and 1,300' from Old Ballard Road. E&S and SWM Narrative—Verdant Lawn Residence Page 3 of 15 No disturbance on adjacent properties will be required. All runoff enters Ivy Creek or its tributary prior to flowing onto any downstream properties. D. PLANNED OFF SITE ACTIVITIES It is not anticipated any off-site cut or fill sites or other types of disturbance will be required. Should additional off-site areas be required, a site plan and erosion and sediment control plan for that area will need to be prepared as an independent project from this project. The contractor shall be responsible for implementing the approved erosion and sediment control plan along with final stabilization and maintenance of all off-site areas. E. SOILS A USDA National Resource Conservation Service (NRCS) Soil Resource Report for the site was obtained. In summary, the majority of the property is classified as Cullen loam or Hayesville loam. The majority of the project areas falls within Map Unit 19B —Cullen loam, 2 to 7 percent slopes and Map Unit 36B - Hayesville loam, 2 to 7 percent slopes. Refer to Appendix A for the complete report with descriptions of each soil type. F. CRITICAL EROSION AREAS Critical slopes as identified by the County GIS are shown on the plans. Minimal disturbance will be made to these slopes. Regular inspections shall be conducted across the entire site to ensure these slope do not become erosive as construction progresses. In general, the contractor shall minimize the areas disturbed at on time and shall immediately apply seed and mulch to denuded areas after work is performed. G. EROSION AND SEDIMENT CONTROL MEASURES Unless otherwise indicated, all vegetative and structural erosion and sediment control measures shall be constructed and maintained according to the latest standards and specifications of the Virginia Erosion and Sediment Control Handbook. Unless waived or approved by local administrator,the minimum standards of VESCR shall apply. MINIMUM STANDARDS: All Minimum Standards must be followed: 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 E&S and SWM Narrative—Verdant Lawn Residence Page 4 of 15 shall be applied within seven days to denuded areas that may not be at final grade but will remain dormant for longer than 14 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 contractor is responsible for the temporary protection and permanent stabilization of all soil stockpiles on site as well as 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 and sediment basins 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. E&S and SWM Narrative—Verdant Lawn Residence Page 5 of 15 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. 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 these 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. c. Effluent from dewatering operations shall be filtered or passed through an 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. e. 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 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 E&S and SWM Narrative—Verdant Lawn Residence Page 6 of 15 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 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 VESCP. Trapped sediment and the disturbed soil areas resulting from the disposition of temporary measures shall be permanently stabilized to prevent further erosion and sedimentation. 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: i (a). 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 ii (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. ii (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 ii (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: E&S and SWM Narrative—Verdant Lawn Residence Page 7 of 15 • i. 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 the bed or banks;or ii. Improve the pipe or pipe system to a condition where the ten-year storm is contained within the appurtenances; or iii. 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 iv. Provide a combination of channel improvement, stormwater detention or other measures which is satisfactory to the VESCP authority to prevent downstream erosion. d. The applicant shall provide evidence of permission to make the improvements. 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 stormwater detention, he shall obtain approval from the VESCP 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 stormwater management criteria, individual lots or parcels in a residential, commercial or industrial development shall not be considered to be separate development projects. Hydrologic parameters that reflect the ultimate development condition shall be used in all engineering calculations. E&S and SWM Narrative—Verdant Lawn Residence Page 8 of 15 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. H. STRUCTURAL PRACTICES 1. TEMPORARY CONSTRUCTION ENTRANCE—3.02 A stone or asphalt pad, located at the point of vehicular ingress and egress to the construction site. The purpose is to prevent or reduce the amount of mud transported to the public road. Sediment dislodged or washed from the vehicle should be contained within a proper sediment trapping area. 2. SILT FENCING—3.05 Silt fence sediment barriers will be installed down slope of disturbed areas to filter sediment laden runoff. 3. INLET PROTECTION—3.07 Inlet protection will be installed on all inlets as they are installed to filter sediment laden runoff before entering storm drain inlets and piping systems. 4. CULVERT INLET PROTECTION—3.08 Stone ring installed around the entrance to culverts to allow sediment to settle before it enters the pipe and is conveyed downstream. 5. TEMPORARY DIVERSION DIKE—3.09 Mounds of earth used to divert clean runoff around the construction activities and to divert runoff from disturbed areas to appropriate trapping measures 6. SEDIMENT TRAP—3.13 A temporary ponding area where sediment laden runoff is diverted and allowed to settle prior to leaving the site. 7. TEMPORARY SLOPE DRAIN—3.15 An above ground pipe used to temporarily convey water down a slope without causing erosion. 8. LEVEL SPREADER-3.21 A Filtrexx Soxx installed at a consistent grade at the outlet of storm pipes to spread the flow over a longer section to prevent erosion of the downstream slopes. 9. DUST CONTROL—3.39 Dust control measures will be used over the whole site to reduce surface and air movement of dust during land disturbance,demolition,and construction activities. E&S and SWM Narrative—Verdant Lawn Residence Page 9 of 15 I. VEGETATIVE PRACTICES GENERAL: A permanent vegetative cover shall be established on denuded areas not otherwise permanently stabilized by concrete, pavement or landscaped mulched beds. Permanent vegetation shall not be considered established until a ground cover is achieved that is uniform, mature enough to survive and will inhibit erosion. New vegetation shall be maintained for one full year after planting. New seeding shall be supplied with adequate moisture, especially late in the season, and in abnormally hot or dry weather. Stabilization practices shall be accomplished in accordance with the appropriate VESCH Std. & Spec. and as per the Erosion and Sediment Control Plan. Selection of the appropriate seed mixture for temporary seeding will depend upon the time of year it is applied. 1. TOPSOILING—3.30 A 2"to 4" layer of topsoil will be applied to all landscaped and grassed areas. The topsoil shall be free of rocks and debris. Topsoil allows a stronger and healthier stand of grass to establish quickly to stabilize unpaved areas of the site. 2. TEMPORARY SEEDING—3.31 Temporary seeding shall be applied over cleared areas that will not be brought to final grade within 14 days. Temporary seeding mixes shall be as described in VESCH Std. & Spec. 3.31. • Sequence of Installation: When cleared areas will not be brought to final grade within 14 days. • Maintenance: Refer to Std. & Spec. 3.31; areas which fail to establish vegetative cover adequate to prevent rill erosion are to be reseeded. • Removal Event: As needed for future earthwork. 3. PERMANENT SEEDING—3.32 Used on all areas at final grade and will not receive hardscape or other landscape. Permanent seeding shall also be used on all areas that are not at final grade and that will be left dormant for a period of more than 1 year. If conflicts exist between the project specifications and the VESCH Std. &Spec. 3.32,the more stringent requirement shall apply.Permanent seeding mixes and rates are found in VESCH Std. & Spec. 3.32. • Sequence of Installation: Within 7 days of achieving final grade • Soil Testing Requirements: Refer to Std. & Spec. 3.32 • Maintenance: Refer to Std. & Spec. 3.32; areas which fail to establish vegetative cover adequate to prevent rill erosion are to be immediately reseeded, following identification of the cause of poor germination. E&S and SWM Narrative—Verdant Lawn Residence Page 10 of 15 4. MULCHING—3.35 Application of plant residues or other suitable materials to the soil surface to prevent erosion by protecting the soil surface from raindrop impact and reducing the velocity of overland flow. It is also used to foster the growth of vegetation by increasing available moisture and providing insulation against extreme heat and cold. Mulching will be applied throughout construction on denuded areas. 5. BLANKET MATTING—3.36 Biodegradable matting installed over steep slopes to hold the earth and seed in place while a good stand of vegetation is established. J. PERMANENT STABILIZATION All areas within the limits of disturbance shall be stabilized with permanent seeding, landscaping,or pavement following the final grading. K. CONSTRUCTION SCHEDULE 1. A pre-construction conference will be required. Contact Albemarle County and all appropriate parties to set up the meeting at least one week prior to starting construction. 2. The contractor is responsible for obtaining for all applicable permits. 3. All items of work necessary to complete this project shall be in compliance with all local, state, and local codes. 4. Prior to any land disturbing activity,contractor shall provide the name,certification information,and contact information of the designated responsible land disturber(RLD) to the Albemarle County. 5. Phase I—Initial E&S Measures and Demolition a. Install construction entrances as shown on the plan. Disturb the minimum area needed to install the entrances.Install Filtrexx Soxx to create sediment trapping areas adjacent to the entrances. b. Construct the sediment trap. Disturb the minimum area needed to install the trap. During construction,temporary diversion should be installed just uphill of the trap to divert all upstream runoff around the trap. Silt fence should also be installed just downstream of the proposed disturbed area. c. Install blanket matting and permanent seeding along all slopes leading to the sediment trap once grading is complete. E&S and SWM Narrative—Verdant Lawn Residence Page 11 of 15 d. Once vegetation has been established within the trap, the temporary silt fence and diversion shall be removed. e. Install perimeter silt fence and diversion dikes. Immediately seed all diversion dikes. f. Install temporary slope drain into the sediment trap. g. Install culvert inlet protection h. Begin demolition of items as shown on the plans. i. Throughout construction activities, apply dust control measures according to VESCH std. & spec. 3.39.Any and all material or debris tracked onto a public or private road surface will be cleaned thoroughly at the end of each day. Sediment shall be removed from roads by shoveling or sweeping and be transported to a sediment controlled disposal area. j. Apply temporary seeding and mulching as necessary. 6. Phase 2—Driveway Construction a. Maintain perimeter erosion and sediment control measures as shown on the plans. Erosion and sedimentation controls shall be maintained until such a time as a vegetative cover is established uphill of the measures. b. Begin clearing and grubbing of the site.Topsoil should be stockpiled and saved for use during final site grading. Clearing and grubbing activities should be performed as needed for the next construction activity and not across the entire site at once. c. All stockpiles shall be surrounded by silt fence and seeded in compliance with MS-19. d. Begin initial grading of the driveway. All excavated material and debris shall be stockpiled or disposed of in a lawful manner. Albemarle County is to be notified prior to any hauling to or from any offsite borrow or waste area. e. Install storm sewer pipes and swales as shown on the plans. Install storm drain inlet protection,outlet protection and level spreaders as the system is installed. f. Use appropriate dust control measures for disturbed areas as well as temporary seeding and straw mulching as necessary. g. Complete driveway construction. h. All stormwater pipes and structures shall be cleaned of all sediment build up. i. Once upstream areas have been stabilized and have established vegetation, removal of the E&S measures associated with the driveway may take place. E&S and SWM Narrative—Verdant Lawn Residence Page 12 of 15 7. Phase 3—House Site Area a. Maintain sediment trap and temporary slope drain from previous phase.Inspect the sediment trap from structural deficiencies and accumulated sediment. Make repairs as required. b. Relocate the construction entrances as shown on the plan. Disturb the minimum area needed to install the entrances. c. Install new perimeter silt fence and diversion dikes. Immediately seed all diversion dikes. d. Begin clearing and grubbing of the site.Topsoil should be stockpiled and saved for use during final site grading. Clearing and grubbing activities should be performed as needed for the next construction activity and not across the entire site at once. e. All stockpiles shall be surrounded by silt fence and seeded in compliance with MS-19. f. Begin initial grading of the house site. All excavated material and debris shall be stockpiled or disposed of in a lawful manner.Albemarle County is to be notified prior to any hauling to or from any offsite borrow or waste area. g. Install additional erosion and sediment control measures as shown on the plans and as deemed necessary by the RLD,engineer or the university. h. Use appropriate dust control measures for disturbed areas as well as temporary seeding and straw mulching as necessary. i. Install storm sewer pipes and drains as shown on the landscape plans. Install storm drain inlet protection,outlet protection and level spreaders as the system is installed. j. Finalize major activities associated with house construction and utility installation. k. Apply permanent seeding and straw mulching to all disturbed area, outside of the hardscape and mulched landscaped areas. 1. All stormwater pipes and structures shall be cleaned of all sediment build up. m. Once upstream areas have been stabilized and have established vegetation, notify the inspectors for an inspection. 8. Phase 4—Finalize Construction a. Once approval is acquired from the inspector,remove all perimeter measure. E&S and SWM Narrative—Verdant Lawn Residence Page 13 of 15 t y b. Reinstall the diversion dikes and silt fence associated with the initial sediment trap construction. c. Begin to remove the sediment trap. Dispose of accumulated sediment in a lawful manor. d. Fill in sediment trap area to return to pre developed grades. e. Apply permanent seeding and straw mulching to all disturbed areas. f. Once the sediment trap area has been stabilized and vegetation is established, notify the inspectors for a final inspection. After final approval, all remaining erosion and sediment control measures shall be removed within 30 days. g. Remove all equipment,construction materials and debris from the site. L.MAINTENANCE Prior to any land disturbing activity, contractor shall provide the name, certification information, and contact information of the designated Responsible Land Disturber(RLD) to Albemarle County. In general, all erosion and sediment control measures will be checked at least every two weeks and/or after each significant rainfall. During construction, the contractor's designated RLD will be responsible for inspecting and repairing damaged erosion/sediment control measures.The following items will be checked in particular: 1. The silt fence barrier will be checked for undermining or deterioration of the fabric. Sediment shall be removed when the level of sediment deposition reaches half way to top of barrier. 2. The sediment trap will be checked for structural integrity and sediment build up. Sediment shall be removed when the level of the sediment reaches half the wet storage depth. 3. Roadways outside of the limits of disturbance shall be checked to ensure minimal sediment and mud is being tracked offsite. Construction entrances shall be upgraded as required. Ensure sediment trapping areas adjacent to the construction entrances are properly capturing and treating the entrance. 4. The seeded and mulched areas will be checked regularly to ensure that a good stand is maintained. Areas should be fertilized and reseeded as needed. Refer to ESC Technical Bulletin#4. 5. Provide remedial stabilization and seeding for a period of one year after construction. E&S and SWM Narrative—Verdant Lawn Residence Page 14 of 15 Part 2: Stormwater Management Report A. STORMWATER MANAGEMENT OVERVIEW The property drains in all directions to the boundary lines. Ivy Creek flows along the west and north sides of the property and one of its tributaries flows along the east side of the property. Ivy Creek flows to the northeast and the tributary flows to the north. A CSX Railroad runs between the property and US Route 250. This blocks the southern runoff and diverts half to the west into Ivy Creek and half to the east into the tributary. The project site area drains into three major valleys on the property. Two of these, analysis point#1 and #2 flow to the west and into the tributary. The third, analysis point #3, drains to the southwest, along the railroad, into an onsite farm pond and into Ivy Creek. All the runoff eventually flows to a point in Ivy Creek to the northeast of the property. B. WATER QUALITY ANALYSIS The overall disturbance associated with this work is approximately 9.6 acres. In the pre- developed condition, there are approximately 0.55 acres of impervious area, or 6% of the project area. In the post-developed condition, there are approximately 1.12 acres of impervious area, or 12% of the project area. The average land cover condition in Virginia is 16% impervious area. Per the Performance Based Water Quality Calculations, development which results in under 16% impervious area is considered a low density development and no water quality measures are required. Using the entire property area of 143.8 acres, the percentage of impervious area is also well below the 16% threshold. C. WATER QUANTITY ANALYSIS Water quantity was analyzed at three points as it leaves the property. The Albemarle County GIS was used to determine the overall drainage area to each point. At all three analysis points,the total drainage area is more than 100 times greater than amount of site area which drains to that point. This triggers the 1% rule, which states no water quantity control measures are required where the project area is less than 1% of the overall drainage area. E&S and SWM Narrative —Verdant Lawn Residence Page 15 of 15