HomeMy WebLinkAboutWPO201400023 Review Comments Stormwater Management Plan 2014-03-28� OF AL
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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: Yancey Elementary School wastewater treatment plan
Plan preparer: W.W. Assoc., [hwhite @wwassociates.net]
Owner or rep.: Albemarle County School Board [lcsnoddy @kl2albemarle.org]
Plan received date: 13 Mar 2014
Date of comments: 27 Mar 2014
Reviewer: Glenn Brooks, P.E.
A. Erosion Control Plan (WP0201400023)
1. Provide limits of clearing and grading.
2. Use diversion dikes to direct drainage to the trap(s).
3. Off -site water through the ditch is being directed through the disturbed area, and released without
protection. Unless there is a way to avoid disturbed area, this is considered sediment laden water.
4. The drip field clearing is too large to be protected by silt fence.
5. Silt fence should not be used across contours, as this will channelize rather than filter.
6. The initial drainage area for the trap was not found. It appears to be the same as the proposed
permanent stormwater facility in the calculation. This misses parts of the disturbed area, and does not
appear to be the worst case.
7. MS -19 must be considered from the discharge points of the project to the receiving stream.
B. Stormwater Management
1. The Yancey school site already has two BMP's on record. Both are on this side of the site. Locations
can be viewed at the county web site GIS application. These must be reflected on the plans.
2. This plan appears to use the rational method for routings. A 24hr rainfall distribution must be used to
demonstrate detention compliance. The analysis should be considering the school development area,
or the area of improvement only.
3. The water quality calculation has used a 4.5 acre area. This is incorrect. The project area in the
erosion control narrative is 2 acres. The drainage area to the facility is 1.28 acres. Ideally, removal
rates should be based on an analysis of the entire school site (not the parcel area, but the school
development area), with an overall approach to stormwater management for the entire development..
If removal rates are to be computed based on the proposed improvements, which would be roughly the
captured area to the facility, this gives about 12% impervious, and a removal rate of about 68% in the
rural areas.
Because the previous comments appear to require substantial revision, further details for the proposed
facilities were not reviewed.
File: E1_ esc, swm _GEB_YanceyWasteTreatment.doc