2022 08 Drainage Report

The Township of West Orange and NJAC 7:8 flow reduction requirements are as follows: 2-year: 50% reduction 10-year: 25% reduction 25-year: Maintain existing flow (no reduction requirement) 100-year: 20% reduction It is the intention of the design of this facility to comply with the Stormwater Management Best Management Practices Manual. Ill. EXISTING D GE CONDITI! The area to be analyzed consists of approximately 3.71 acres and is comprised of impervious, brush and wooded areas. Currently, the majority of stormwater runoff generated by the subject site drains to Mount Pleasant Avenue at the south-east corner of the site through overland flow. The subject site has been evaluated with the following drainage sub-watershed areas as depicted on the Existing Drainage Area Map included within the Appendix of this report. Study Area Mount Pleasant Avenue: This area consists of the entire site to be disturbed, which includes impervious, brush and wooded areas. As noted above, under existing conditions, stormwater runoff generated by this area is ultimately tributary to Mount Pleasant Avenue via overland flow. SOIL TYPE SOIL TYPE NAME Ecce BogCc Boonton loam, 8 to 15 percent slopes, extremely stony € HanBe Haledon silt loam, 0 to 8 percent slopes, extremely stony Cc YaobBe Yalesville — Boonton — Holyoke complex, 0 to 8 percent slopes, c extremely stony USBONB [1] Urban land, Boonton substratum — Boonton complex, 0 to 8 percent slopes [1] No soil group was provided by NRCS, therefore B rating was assumed for existing conditions while D rating soils were assumed for proposed conditions. SHI Builders August 2022 DEC# 4266-99-001 -2-