2026 05 05 Response Letter rcd 5 6 2026

Mavis Tire Supply, LLC May 5, 2026 Page 7 of 21 9. Table 5-1 on page 5 of the stormwater report states that the bioretention basin does not have a maximum drain time since underdrains are proposed which is incorrect. The capacity of the underdrain system must be sufficient to allow the basin to drain within 72 hours while still retaining moisture below the surface for uptake by vegetation. Response: The enclosed Stormwater Report has been revised to provide basin drain time calculations and note the calculated drain time within Table 5-1 of the stormwater report. 10. The Point of Analysis #1 Table on page 6 shows that the proposed peak flow rate will be reduced for each storm event. However, it remains for the Applicant to demonstrate that the post-construction runoff hydrographs for the current and projected 2 year, 10 year and 100 year storm events will not exceed, at any point in time, the pre-construction hydrographs for the same storm events. Response: The Applicant requests a waiver from §25-29.4.s, to permit a deviation from strict compliance with this requirement. Testimony will be provided at the Zoning Board hearing. 11. The stormwater collection system calculations in the stormwater report must be revised to consider the stormwater conveyed through the existing 6" CIP upstream of the existing round inlet. Response: The pipe sizing calculations have been revised to account for the existing 6” CIP pipe upstream of the round inlet. Our office conservatively assumed the pipe will be flowing full into the proposed stormwater conveyance system. An upstream invert to the building was not identified, therefore, a conservative slope of 5% was utilized which follows the approximate pavement surface grade along the pipe run. 12. The stormwater report has a section which shows the results of several test pits performed on site. The test pit locations must be shown on the plans. At this time, our office cannot confirm if the required number of test pits were performed or if the minimum separation from the seasonal high water table to proposed basin was met. Response: The grading, drainage, and utility plans have been revised to indicate the locations of where the soil test pits and borings were performed on site, per the Infiltration Testing Report prepared by ECS. 13. The drainage area maps and hydrograph summary reports must be revised to include a separate

soil test pits and borings were performed on site, per the Infiltration Testing Report prepared by ECS. 13. The drainage area maps and hydrograph summary reports must be revised to include a separate drainage area within the ROW as sidewalk is now proposed. Response: The enclosed Stormwater Report has been revised to include a separate drainage area within the ROW to account for the proposed sidewalk.