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HomeMy WebLinkAboutWPO200800041 Review Comments Stormwater Management Plan 2008-04-25ALg�,�� �'IRGINZ� COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, Room 227 Charlottesville, Virginia 22902 -4596 Phone (434) 296 -5832 Fax (434) 972 -4126 Project: SDP - 2007 - 00105, Brownsville Elementary School, Major Amendment Plan preparer: Scott Collins , Collins Engineering [email: scott @collins -en ing eering com] Owner or rep.: Joseph Werres, County of Albemarle [email: jwerres @albemarle.orc] Date received: 09 October 2007 (plan date 08 October 2007) Rev.l 09 January 2008 (plan date 01 January 2008) Rev2: 11 Apr 2008 Date of Comment: 10 October 2007 Rev.1 08 February 2008 Rev2: 25 Apr 2008 Engineer: Allan Schuck Rev.1 Max Greene Rev2: Jonathan Sharp [phone: 566 -2578] All comments for the major amendment to the final site plan for Brownsville Elementary School have been addressed. All ESC and SWM comments must be addressed prior to major amendment approval. A. Final Major Amendment: An approved E &SC and SWM plan are required before the final site plan can be approved. B. Stormwater Management Plans 1. The 48" manhole (Structure 22) should be sized larger because of the 42" pipe running to it. This may have an affect on the outlet structure weir dimensions. 2. Please label the elevations of the orifice and weir, and label the weir length and location in the manhole (is it centered in the manhole ?). 3. The low flow orifice should specify a trash rack. 4. Please specify the critical durations used for the 2, 10, and 100 year routings. 5. The raintank detail specifies a cover of 2 feet required over the facility, when only 1 foot is provided at the north -east corner of the facility. 6. The control structure information in the calculation package does not match the plans. 7. A SWM bond is not computed for County projects. C. Erosion and Sediment Control Plans 8. Please provide the Albemarle County Erosion Control Notes, verbatim (provided following comments). 9. Please show the outlet protection symbol at the outlet of the SWM facility. 10. The drainage area map going to the facility appears to be wrong in some areas. Drainage may exceed 3 acres; a basin may be necessary. 11. The wet storage for the trap cannot exceed 4 feet in depth. 12. Please provide an adequate channel analysis for the swale downstream of the facility running to the buffered stream. 13. An ESC bond is not computed for County projects. General construction notes for Erosion and Sediment Control plans 1. 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. 5. 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. 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. 9. 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 50150 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 901bs /1000sf, incorporated into the top 4 -6 inches of soil. Fertilizer shall be applied at 10001bs /acre and consist of a 10 -20 -10 nutrient mix. Permanent seeding shall be applied at 180lbs /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 80lbs /100sf. Alternatives are subject to approved by the County erosion control inspector. 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.