26 03 25 CME Engineering Review 2

—=—_ ; Consulting & Municipal ee ENGINEERS A Subsidiary of Artheon, Inc. Chairman and Members of the West Orange Township Zoning Board March 25, 2026 Re: Mavis Tire Supply, LLC (ZB-25-07) Our File No. 115.WRZ0105.V01 (60001) Preliminary & Final Major Site Plan with ‘C’ & ‘D’ Page 6 Variances and Tree Removal Permit - Review #2 3. The Applicant proposes to have the roof runoff discharge to the underground detention basin. It states in Chapter 11.2 of the New Jersey Stormwater Best Management Practices Manual that an extended detention basin (Non-Gl) can only be used to address the stormwater runoff quantity control aspects of the development when a waiver or variance is obtained from N.J.A.C. 7:8-5.3 as it is not considered to be green infrastructure. Therefore, the Applicant requires a waiver from §25-29.4p (green infrastructure standards) of the Ordinance. 4. The stormwater report should be revised to include stability calculations for the stone riprap in the bioretention basin. 5. The times of concentration shown in the Existing Conditions input Summary Table on page 3 do not match the times of concentration in the hydrograph summary reports. Revise accordingly. 6. The existing peak flow rates shown in the Existing Conditions Flow Summary Table on page 3 and in the Point of Analysis #1 Table on page 6 of the stormwater report do not match the existing peak flow rate in the hydrograph summary reports. Revise accordingly. 7. The following information shown in the Proposed Conditions Input Summary Table on page 4 of the stormwater report does not match the same within the hydrograph summary reports. The time of concentration of PDA-Bioretention Basin (Pervious) sf The time of concentration of PDA-Bioretention Basin (Impervious) The drainage area of PDA-Uncontrolled (Pervious) The time of concentration of PDA-Uncontrolled (Pervious) The drainage area of PDA-Uncontrolled (Impervious) ™~@ 20 The time of concentration of PDA-Uncontrolled (impervious) Revise accordingly. 8. The proposed peak flow rates shown in the Proposed Conditions Flow Summary Table on page 4 of the stormwater report do not match the Point of Analysis #1 Table on page 6 of the stormwater report nor the proposed peak flow rate in the hydrograph summary reports. Revise accordingly. 9. Table 5-1 on page 5 of the stormwater report states that the bioretention basin does not have a

mwater report nor the proposed peak flow rate in the hydrograph summary reports. Revise accordingly. 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. 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. H:\Legacy\Howell-FS1\SEC\West Orange\Zoning Board\1 15 WRZ0105 VO1 - Mavis Tire Supply, LLC\26-03-25 Review #2.dacx