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HomeMy WebLinkAboutWPO201100037 Correspondence 2023-02-01ROUDABUSH, GALE & ASSOC. , Inc. A PROFESSIONAL CORPORATION Serving Virginia Since igg6 MONTH DAY. 2023 Mr. David James Albemarle County Community Development 401 McIntire Road Charlottesville, VA 22902 RE: WPO 201100037 Dear Mr. James, I have reviewed your comments dated January 4, 2023 and I am offering my responses below in bold. 1. Sheet 2: a. There may be additional drainage area not accounted for with the 15" pipe. Please verify total drainage area to ext. detention. 15" pipe from under Carroll Creek Rd to forebay not shown correctly. Response: An aerial survey was conducted by RGA on 1/9/2023 to determine the as -built topography of the site and a follow-up field visit on 1/10/2023 confirmed the presence of a ditch along the northern perimeter of the as -built drainage area. The updated drainage area has been shown on this submittal, including the area being captured by the 15" pipe under Carroll Creek Road. The total drainage area has been updated from 5.44 acres to 5.54 acres on both the as -built plan and the as -built calculations. b. Show as built site condition. Response: As -built site conditions as captured in the 1/9/2023 aerial survey have been included on Sheet 2 in the "As -Built Drainage Area" inset in addition to the previously captured as -built data pertaining to the SWM facility and a photomosaic of the site from the aerial survey. c. Provide percent impervious area treated by the ext. det. Response: Acreage and percent impervious area have been included on Sheet 2 in the "As -Built Drainage Area" inset. The calculations have also been updated to include the as -built impervious percent of the drainage area (18.6%). 999 Second Street SE. Charlottesville. VA 22902. www.Roudabush.com 434.977.0205 WP0201100037 Glenmore K2B Phase A 1/31/2023 2. Sheet 3: a. Show the as -built design WSE of ext. Det. Response: The as -built WSE of the extended detention facility, as measured in the updated as -built calculations have been provided on Sheet 3 in the "Extended Detention Basin #1," "Forebay Spillway," and "Emergency Spillway" insets. b. Correct the as -built information shown in the 'Riser/Emergency Spillway' detail. Response: The emergency spillway crest elevation was corrected from 299.8' to 300.1' in the "Riser/Emergency Spillway" detail on Sheet 3. The'W' through "24" CL. III RCP MULTI -STAGE RISER" has been removed and the text has been boxed to indicate that this is the correct size and material for the riser. Boxes have been added around other details to confirm as -built status. 3. Provide level spreader detail. Response: A level spreader detail has been provided on Sheet 3 of this submittal. 4. Show the grading of the LS channel on the up -stream side of the lip. Response: Updated grading has been provided, based on the aerial survey performed by RGA on 1/10/2023 showing the grading of the level spreader on the up -stream side of the lip and extending further to either side of the level spreader to show a greater level of detail than on the previous submittal. The grading for the SWM facility has remained unchanged from the previous submittal, and is shown with 1' contours, as opposed to the remainder of the site, which uses 2' contours. 5. Show 3' wide section of #3 or #57 stone, underlain by filter fabric installed below the lip. Response: This has not been provided. The developer has been notified. 6. Recommend at least 9-in depth in LS channel. Response: The level spreader channel is in excess of 9-inch depth, as shown on the level spreader detail on Sheet 3. 7. Recommend the ends of LS be tied back into slope to avoid scouring around the ends. Response: The developer has been notified of this recommendation. 999 Second Street SE. Charlottesville. VA 22902. www.Roudabush.com Page 2 of 3 WP0201100037 Glenmore K2B Phase A 1/31/2023 Reports/CRDs: 1. Please submit easement plat for the SWM facility easement adjustment. Easement to be recorded prior to release. Response: The easement plat for the SWM facility easement adjustment has not been recorded yet at the time of this submittal. I believe these responses adequately address your comments related to the previous as - built submittal. Please review them and do not hesitate to reach out with any questions or comments about this letter or the updated submittal. Sincerely, Colin Sahs 999 Second Street SE. Charlottesville. VA 22902. www.Roudabush.com Page 3 of 3