complete drainage report rev 9

West Essex Highlands West Orange Twp, NJ 8/26/24 Sizing Basis: Filterra High Capacity biofiltration system has received final certification from the NJDEP for 80% TSS removal. Per the NJDEP, Filterra HC is considered a Green Infrastructure (GI) MTD. The sizing for the Filterra HC system under NJDEP regulations is based on the methodology outlined in Chapter 5 of the NJDEP BMP Manual. The NRCS method is utilized to determine a water quality flow rate for the drainage area in question. To validate the sizing, the parameters below were assumed. Design Parameters: Design Storm = Filterra HC Media Flow Rate = Allowable Ponding in Filterra = NJDEP Water Quality Design Storm (1.25-inch/2-hour storm event) 300 inches/hour 9” Design Summary: Utilizing NRCS Method and HydroCAD software, a hydrograph can be derived to represent the design storm. The WQ flow is routed to an appropriately sized Filterra unit. Since the Filterra system can provide up to 9” of ponding, some flow attenuation is possible. The Filterra system is able to accommodate a portion of the water quality volume in the head space above the media and release it at the system’s NJDEP certified maximum treatment flow rate. Site Designation Impervious Drainage Area (sf) Pervious Drainage Area (sf) Tc (min) POA-3-FT-1 963 3,241 5.40 4'x4' Standard Offline Filterra HC POA-3-FT-2 1,325 1,537 5.40 4'x4' Standard Offline Filterra HC MTD-3 2,008 1,368 0.70 6'x4' Standard Offline Filterra HC MTD-4 7,201 9,187 1.50 12'x6' Standard Offline Filterra HC MTD-9 2,050 270 1.50 6'x4' Standard Offline Filterra HC MTD-10 3,893 5,247 1.50 8'x6' Standard Offline Filterra HC MTD-11 6,684 8,130 1.80 12'x6' Standard Offline Filterra HC MTD-12 2,694 1.80 6'x4' Standard Offline Filterra HC MTD-13 5,554 1.20 10'x6' Standard Offline Filterra HC MTD-14 2,943 1.10 7.83'x4.5' Standard Offline Filterra HC MTD-15 869 368 0.40 4'x4' Standard Offline Filterra HC MTD-16 957 216 0.60 4'x4' Standard Offline Filterra HC MTD-17 4,626 1,159 1.60 8'x6' Standard Offline Filterra HC MTD-18 4,582 1,677 1.50 8'x6' Standard Offline Filterra HC MTD-21 2,050 270 1.30 6'x4' Standard Offline Filterra HC MTD-22 3,893 5,247 1.30 8'x6' Standard Offline Filterra HC 3,290 Filterra HC Model Size Thank you for the opportunity to present this to you and your client. Please do

dard Offline Filterra HC MTD-22 3,893 5,247 1.30 8'x6' Standard Offline Filterra HC 3,290 Filterra HC Model Size Thank you for the opportunity to present this to you and your client. Please do not hesitate to contact me should you have any additional questions. Sincerely, Taylor Murdock Project Engineer Contech Engineered Solutions, LLC.