Public Township Council Meeting — Packet

DRAFT PROPOSED REVISIONS – OCTOBER 2011 40 0.1660 105 1.2250 45 0.2000 110 1.2334 50 0.2583 115 1.2417 55 0.3583 120 1.2500 60 0.6250 2. For purposes of TSS reduction calculations, Table 2 below presents the presumed removal rates for certain BMPs designed in accordance with the New Jersey Stormwater Best Management Practices Manual. The BMP Manual may be obtained from the address identified in subsection 25-29.7, or found on the Department's website at www.njstormwater.org. The BMP Manual and other sources of technical guidance are listed in subsection 25-29.7. TSS reduction shall be calculated based on the removal rates for the BMPs in Table 2 below. Alternative removal rates and methods of calculating removal rates may be used if the design engineer provides documentation demonstrating the capability of these alternative rates and methods to the review agency. A copy of any approved alternative rate or method of calculating the removal rate shall be provided to the Department at the following address: Division of Watershed Management, New Jersey Department of Environmental Protection, PO Box 418, Trenton, New Jersey, 08625-0418. 3. If more than one BMP in series is necessary to achieve the required eighty (80%) percent TSS reduction for a site, the applicant shall utilize the following formula to calculate TSS reduction: R = A + B - (AxB)/100 Where R = total TSS percent load removal from application of both BMPS, and A = the TSS percent removal rate applicable to the first BMP B = the TSS percent removal rate applicable to the second BMP Table 2: TSS Removal Rates for BMPs Best Management Practice TSS % Removal Rate Bioretention Systems 90 Constructed Stormwater 90 Wetland Extended Detention Basin 40-60 Infiltration Structure 80 Manufactured

90 Constructed Stormwater 90 Wetland Extended Detention Basin 40-60 Infiltration Structure 80 Manufactured Treatment Device See subsection 25-29.6c. Sand Filter 80 Vegetative Filter Strip 60-80 Wet Pond 50-90 4. If there is more than one onsite drainage area, the eighty (80%) percent TSS removal rate shall apply to each drainage area, unless the runoff from the subareas converge on site in which case the removal rate can be demonstrated through a calculation using a weighted average. 5. Stormwater management measures shall also be designed to reduce, to the maximum extent feasible, the post-construction nutrient load of the anticipated load from the developed site in stormwater runoff generated from the water quality design storm. In achieving reduction of nutrients to the maximum extent feasible, the design of the site shall include nonstructural strategies and structural measures that optimize nutrient removal while still achieving the performance standards in subsections 25-29.4f. and g. 166