CME Associates Review 2

\ ASSOCIATES Chairman and Members of the West Orange Township Planning Board July 29, 2024 Re: West Essex Highlands, LLC (PB 24-01) Our File No. VWRP0179.01 Preliminary & Final Site Plan - Review #2 Page 9 10. Submit a clear Post-Development Drainage Area Map that is to scale. 11. We note that the Point of Analysis (POA) in the Pre- and Post-Development Drainage Area maps are inconsistent; the POA’s should be the same to verify consistency in the analysis. The stormwater analysis should be revised as necessary. 12. The impervious time of concentration calculations for large scale infiltration basin #1, small scale infiltration basin #2, porous pavement system #3, small scale infiltration basin #7, porous pavement system #8, porous pavement system #9, small scale infiltration basin #10, porous pavement system #11, and small scale subsurface infiltration basin #12 must be revised. It is not acceptable to use a pervious time of concentration calculation for impervious areas. 13. The Post-Development Drainage Area Map must be revised to depict time of concentration flow paths for DA #2, DA #3, DA #7, DA #8, and the un-detained drainage areas. Additionally, the Tc line for DA #10 must be labeled. 14. The overland flow areas listed for DA #1 and DA #6 on the Post-Development Drainage Area Map shall be reviewed for consistency with the areas listed in the “Total Undetained to PA-1” note as the overland flow areas do not add to the total un-detained area. 15. The overland flow areas listed for DA #2, DA #4, DA #7, DA #9, DA #10 and DA #11 on the Post-Development Drainage Area Map shall be reviewed for consistency with the areas listed in the “Total Undetained to PA-2” note as the overland flow areas do not add to the total un-detained area. 16. The ‘Total Undetained to PA-1’ and ‘Total Undetained to PA-2’ notes on the Post- Development Drainage Area Map shall be evaluated. It appears un-detained impervious areas are incorrectly indicated as ‘pervious’ and un-detained pervious areas are incorrectly indicated as ‘pervious’. This discrepancy must be resolved. 17. Sheet SP-21 depicts a 24” HDPE inlet pipe to large-scale basin #1 at invert elevation 24.00, whereas the basin bottom is at elevation 23.50. This discrepancy must be resolved. Further, the basin bottom at elevation 23.50 must be depicted on the plan. 18. The top of grate elevation for outlet

whereas the basin bottom is at elevation 23.50. This discrepancy must be resolved. Further, the basin bottom at elevation 23.50 must be depicted on the plan. 18. The top of grate elevation for outlet structure #1 is inconsistent between Sheet SP-21, SP- 25 and the hydrographs. This discrepancy must be resolved. 49. Sheet SP-25 must be revised to indicate top of grate in lieu of ‘100 year overflow elevation’ on the outlet structure #1 detail. 20. The Stormwater Management Report indicates that exfiltration will be utilized for small scale infiltration basin #2, however, the hydrograph routings do not include exfiltration. This discrepancy must be clarified. ‘S:\West Orange\Pianning Board\VWRPO179,01 - West Essex Highlands, Inc\Review #2 07-29-24 docx