2026 05 Storm Water Management Report rcd 5 6 2026

Point of Analysis #1 Storm Event Existing Peak Proposed Peak Percent Flow Rate (cfs) Flow Rate (cfs)* Reduction Current 2-year 1.44 1.35 6.3% Current 10-year 2.41 2.18 9.5% Current 100-year 4.45 4.27 4.0% Projected 2-year 1.75 1.64 6.3% Projected 10-year 2.94 2.61 11.2% Projected 100- 5.76 5.59 3.5% year Point of Analysis #2 Storm Event Existing Peak Proposed Peak Flow Rate (cfs) Flow Rate (cfs)* Current 2-year 0.07 0.11 Current 10-year 0.14 0.24 Current 100-year 0.30 0.37 Projected 2-year 0.09 0.14 Projected 10-year 0.18 0.24 Projected 100- 0.41 0.47 year *Increase in proposed peak flow rate is due to addition of sidewalk within the Prospect Avenue right-of-way at the request of the Township. Increase in flows do not exceed 0.10 cfs and can be considered de minimus. Point of Analysis #3 Storm Event Existing Peak Proposed Peak Flow Rate (cfs) Flow Rate (cfs)* Current 2-year 0.09 0.13 Current 10-year 0.22 0.25 Current 100-year 0.53 0.52 Projected 2-year 0.13

0.22 0.25 Current 100-year 0.53 0.52 Projected 2-year 0.13 0.17 Projected 10-year 0.30 0.33 Projected 100-year 0.76 0.69 *Drainage area to POA #3 is reduced as a result of the development, however, a small increase in peak flows occurs due to the HSG D soils being utilized for the proposed condition while HSG B soils are utilized for calculations in the existing condition. Increase in flows are less than 0.05 cfs can be considered de minimus. 8. Water Quality Compliance In accordance with the West Orange Stormwater Control Ordinance, section 25-29.4.r.2(a), major developments are required to provide 80% TSS removal for the stormwater runoff from the net increase in motor vehicle surface. The project proposed a net decrease of motor vehicle surface of 0.009 acres (0.276 acres in the existing condition and 0.267 acres in the proposed condition) therefore water quality is not required, however, the proposed bioretention basin has been designed to treat 0.064 acres of motor vehicle surface in the proposed condition to 80% TSS removal. For reference, the project proposes a net increase in on-site impervious area of 0.04 acres. Mavis Tire Supply, LLC July 2025 DEC# 1956-24-04187 8 Last revised May 2026