Text · page 7 of 351
Engineer’s Report December 2025 in Appendix A. The proposed development will disturb approximately 0.54± acres (0.01± acres of total disturbance area is within Quaker Road ROW (US 20A) for pavement connection and restoration) and will consist of 0.31± acres of pervious area with 0.39± acres of impervious area. Because the proposed development is a redevelopment with a disturbance area less than one acre, only erosion and sediment control measures are required. Hydrographs representing pre-development and post-development runoff have been generated using the Soil Conservation Service-TR-55 and TR- 20 methodology utilizing HydroCAD software. Hydrographs for the 1, 10, 25, and 100-year storm events under existing conditions and the 1, 10, 25, and 100-year storm events under proposed conditions were generated and are included in Appendix A. The post developed discharge rates from the proposed stormwater conveyance system will not exceed the existing runoff rates for the 1-year, 10-year, 25-year, and 100-year storm events of the corresponding pre-development drainage area. The following table summarizes these pre-development and post development peak runoff conditions for the project site: Stormwater Runoff Summary Proposed Swale Pre-Development Post Development High Water Peak Runoff Rate Peak Runoff Rate Elevation (ft) (cfs) (cfs) Top of Bank 902.00 (Link “PRE”) (Link “POST”) (Pond “SWALE”) 1-Year 0.45 0.45 900.91 10-Year 1.07 0.93 901.23 25-Year 1.46 1.24 901.40 100-Year 2.29 2.11 901.93 3. NYSDEC SPDES General Permit The proposed development will result in less than 1-acre of soil disturbance and therefore does not require a NYSDEC SPDES General Permit for Stormwater Discharges from Construction Activity, GP-0-25-001 or preparation of the associated Stormwater Pollution Prevention Plan (SWPPP). However, temporary erosion and sediment control measures were incorporated into the design plans. Greenman-Pedersen, Inc. GPI No. WNY-2500056.00 Page 7