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Home My WebLink AboutWPO202000034 Action Letter 2020-11-04COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, North Wing Charlottesville, Virginia 22902-4596 Phone (434) 296-5832 Fax (434) 972-4126 November 4, 2020 Mr. Jim Taggart, PE Roudabush, Gale & Associates, Inc. 999 Second Street, SE Charlottesville, VA 22902 RE: WPO202000034 Belvedere Phase 5 — VSMP VSMP Variance Request — Energy Balance Compliance Dear Mr. Taggart, Your request for a variance from the energy balance standards (9VAC25-840-66.B.3) for channel protection is approved. Calculations indicate a maximum flowrate of Q=0.143 cis is required to satisfy energy balance requirements. This results in an orifice size of 1-inch. Based on existing facilities with low -flow orifices, a 1-inch orifice is highly prone to clogging and will not function without consistent maintenance. Therefore, a 3-inch orifice was modeled and the flow from this orifice results in a discharge of Q=0.494 cis. This variance requests the use of a 3-inch orifice instead of a 1-inch orifice. Considering the discharge is below 1 cfs and the increase from 0.143 cfs to 0.494 cfs is considered insignificant from the perspective of providing channel protection, this request is approved. Sin ly, V F ank V. Pohl, PE, CFM County Engineer COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, North Wing Charlottesville, Virginia 22902-4596 Phone (434)296-5532 Fax (434) 972-4126 November 4, 2020 Mr. Jim Taggart, PE Roudabush, Gale & Associates, Inc. 999 Second Street, SE Charlottesville, VA 22902 RE: WP0202000034 Belvedere Phase 5 — VSMP VESCP Variance Request — Mud Traps Dear Mr. Taggart, Your request to utilize modified mud traps for the referenced project as shown on the approved plans is approved. Mud traps are not included in the VESCH, however, considering the application, the relatively small contributing drainage area, and the proximity to the stream, this type of measure is allowed if constructed and maintained properly. This approval does not waive the authority of the Erosion and Sediment Control Inspector to require additional measures or revoke this variance if these measures are deemed to be inadequate or are improperly maintained. Sjncerely, ran PE, CFM County Engineer