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any stormwater runoff in a discharge regulated under a numeric effluent limitation for TSS imposed under the New Jersey Pollution Discharge Elimination System (NJPDES) rules, N.J.A.C. 7:14A, or in a discharge specifically exempt under a NJPDES permit from this requirement. The water quality design storm is one and one-quarter (1.25) inches of rainfall in two (2) hours. Water quality calculations shall take into account the distribution of rain from the water quality design storm, as reflected in Table 1. The calculation of the volume of runoff may take into account the implementation of nonstructural and structural stormwater management measures. Table 1: Water Quality Design Storm Distribution Cumulative Cumulative Time Rainfall Time Rainfall (Minutes) (Inches) (Minutes) (Inches) 0 0.0000 65 0.8917 5 0.0083 70 0.9917 10 0.0166 75 1.0500 15 0.0250 80 1.0840 20 0.0500 85 1.1170 25 0.0750 90 1.1500 30 0.1000 95 1.1750 35 0.1330 100 1.2000 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 142

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 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

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. 6. Additional information and examples are contained in the New Jersey Stormwater Best Management Practices Manual, which may be obtained from the address identified in subsection 25-29.7. 143

7. In accordance with the definition of FW1 at N.J.A.C. 7:9B-1.4, stormwater management measures shall be designed to prevent any increase in stormwater runoff to waters classified as FW1. 8. Special water resource protection areas shall be established along all waters designated Category One at N.J.A.C. 7:9B and perennial or intermittent streams that drain into or upstream of the Category One waters as shown on the USGS Quadrangle Maps or in the County Soil Surveys, within the associated HUC14 drainage. These areas shall be established for the protection of water quality, aesthetic value, exceptional ecological significance, exceptional recreational significance, exceptional water supply significance, and exceptional fisheries significance of those established Category One waters. These areas shall be designated and protected as follows: (a) The applicant shall preserve and maintain a special water resource protection area in accordance with one of the following: (1) A 300-foot special water resource protection area shall be provided on each side of the waterway, measured perpendicular to the waterway from the top of the bank outwards or from the centerline of the waterway where the bank is not defined, consisting of existing vegetation or vegetation allowed to follow natural succession is provided. (2) Encroachment within the designated special water resource protection area under paragraph (1) above shall only be allowed where previous development or disturbance has occurred (for example, active agricultural use, parking area or maintained lawn area). The encroachment shall only be allowed where applicant demonstrates that the functional value and overall condition of the special water resource protection area will be maintained to the maximum extent practicable. In no case shall the remaining special water resource protection area be reduced to less than one hundred fifty (150) feet as measured perpendicular to the top of bank of the waterway or centerline of the waterway where the bank is undefined. All encroachments proposed

et as measured perpendicular to the top of bank of the waterway or centerline of the waterway where the bank is undefined. All encroachments proposed under this subparagraph shall be subject to review and approval by the Department. (b) All stormwater shall be discharged outside of and flow through the special water resource protection area and shall comply with the Standard for Off-Site Stability in the "Standards for Soil Erosion and Sediment Control in New Jersey," established under the Soil Erosion and Sediment Control Act, N.J.S.A. 4:24-39 et seq. (c) If stormwater discharged outside of and flowing through the special water resource protection area cannot comply with the Standard for Off-Site Stability in the, "Standards for Soil Erosion and Sediment Control in New Jersey," established under the Soil Erosion and Sediment Control Act, N.J.S.A. 4:24-39 et seq., then the stabilization measures in accordance with the requirements of the above standards may be placed within the special water resource protection area, provided that: (1) Stabilization measures shall not be placed within one hundred fifty (150) feet of the Category One waterway; (2) Stormwater associated with discharges allowed by this section shall achieve a ninety-five (95%) percent TSS post-construction removal rate; (3) Temperature shall be addressed to ensure no impact on receiving waterway; 144

(4) The encroachment shall only be allowed where the applicant demonstrates that the functional value and overall condition of the special water resource protection area will be maintained to the maximum extent practicable; (5) A conceptual project design meeting shall be held with the appropriate Department staff and Soil Conservation District staff to identify necessary stabilization measures; and (6) All encroachments proposed under this subsection shall be subject to review and approval by the Department. (d) A stream corridor protection plan may be developed by a regional stormwater management planning committee as an element of a regional stormwater management plan, or by a municipality through an adopted municipal stormwater management plan. If a stream corridor protection plan for a waterway subject to subsection 25- 29.4g,8. has been approved by the Department of Environmental Protection, then the provisions of the plan shall be the applicable special water resource protection area requirements for that waterway. A stream corridor protection plan for a waterway subject to paragraph g,8. shall maintain or enhance the current functional value and overall condition of the special water resource protection area as defined in paragraph g,8(a)(1) above. In no case shall a stream corridor protection plan allow the reduction of the Special Water Resource Protection Area to less than one hundred fifty (150) feet as measured perpendicular to the waterway subject to this subsection. (e) This subsection does not apply to the construction of one (1) individual single family dwelling that is not part of a larger development on a lot receiving preliminary or final subdivision approval on or before the effective date of the Stormwater Management Rules*, provided that the construction begins on or before five (5)

or final subdivision approval on or before the effective date of the Stormwater Management Rules*, provided that the construction begins on or before five (5) years from effective date of the Stormwater Management Rules.* (Ord. No. 2063-06 § 4) 25-29.5 Calculation of Stormwater Runoff and Groundwater Recharge. a. Stormwater runoff shall be calculated in accordance with the following: 1. The design engineer shall calculate runoff using one of the following methods: (a) The USDA Natural Resources Conservation Service (NRCS) methodology, including the NRCS Runoff Equation and Dimensionless Unit Hydrograph, as described in the NRCS National Engineering Handbook Section 4-Hydrology and Technical Release 55 - Urban Hydrology for Small Watersheds; or (b) The Rational Method for peak flow and the Modified Rational Method for hydrograph computations. 2. For the purpose of calculating runoff coefficients and groundwater recharge, there is a presumption that the preconstruction condition of a site or portion thereof is a wooded land use with good hydrologic condition. The term "runoff coefficient" applies to both the NRCS methodology at subsection 25-29.5a,1(a) and the Rational and Modified Rational Methods at subsection 25-29.5a,1(b). A runoff coefficient or a groundwater recharge land cover for an existing condition may be used on all or a portion of the site if the design engineer verifies that the hydrologic condition has existed on the site or portion of the site for at least five (5) years without interruption prior to the time of application. If more than one (1) land cover have existed on the site during the five (5) years immediately prior to the time of application, the land cover with the lowest runoff potential shall be * Editor's Note: Ordinance No. 2063-06 codified herein was adopted March 21, 2006. 145

used for the computations. In addition, there is the presumption that the site is in good hydrologic condition (if the land use type is pasture, lawn, or park), with good cover (if the land use type is woods), or with good hydrologic condition and conservation treatment (if the land use type is cultivation). 3. In computing preconstruction stormwater runoff, the design engineer shall account for all significant land features and structures, such as ponds, wetlands, depressions, hedgerows, or culverts that may reduce preconstruction stormwater runoff rates and volumes. 4. In computing stormwater runoff from all design storms, the design engineer shall consider the relative stormwater runoff rates and/or volumes of pervious and impervious surfaces separately to accurately compute the rates and volume of stormwater runoff from the site. To calculate runoff from unconnected impervious cover, urban impervious area modifications as described in the NRCS Technical Release-55, Urban Hydrology for Small Watersheds and other methods may be employed. 5. If the invert of the outlet structure of a stormwater management measure is below the flood hazard design flood elevation as defined at N.J.A.C. 7:13, the design engineer shall take into account the effects of tailwater in the design of structural stormwater management measures. b. Groundwater recharge may be calculated in accordance with the following: 1. The New Jersey Geological Survey Report GSR-32 A Method for Evaluating Ground- Water Recharge Areas in New Jersey, incorporated herein by reference as amended and supplemented. Information regarding the methodology is available from the New Jersey Stormwater Best Management Practices Manual; at http://www.state.nj.us/dep/njgs/; or at New Jersey Geological Survey, 29 Arctic Parkway, P.O. Box 427, Trenton, New Jersey 08625-0427; (609) 984-6587. (Ord. No. 2063-06 § 5) 25-29.6 Standards for Structural Stormwater Management Measures. a. Standards for structural stormwater management measures are as follows: 1. Structural stormwater management measures shall be designed to take into account the existing site conditions,

andards for structural stormwater management measures are as follows: 1. Structural stormwater management measures shall be designed to take into account the existing site conditions, including, for example, environmentally critical areas, wetlands; flood-prone areas; slopes; depth to seasonal high water table; soil type, permeability and texture; drainage area and drainage patterns; and the presence of solution-prone carbonate rocks (limestone). 2. Structural stormwater management measures shall be designed to minimize maintenance, facilitate maintenance and repairs, and ensure proper functioning. Trash racks shall be installed at the intake to the outlet structure as appropriate, and shall have parallel bars with one (1) inch spacing between the bars to the elevation of the water quality design storm. For elevations higher than the water quality design storm, the parallel bars at the outlet structure shall be spaced no greater than one-third (1/3) the width of the diameter of the orifice or one-third (1/3) the width of the weir, with a minimum spacing between bars of one (1) inch and a maximum spacing between bars of six (6) inches. In addition, the design of trash racks must comply with the requirements of subsection 25-29.8d. 3. Structural stormwater management measures shall be designed, constructed, and installed to be strong, durable, and corrosion resistant. Measures that are consistent with the relevant portions of the Residential Site Improvement Standards at N.J.A.C. 5:21-7.3, 7.4, and 7.5 shall be deemed to meet this requirement. 4. At the intake to the outlet from the stormwater management basin, the orifice size shall be a minimum of two and one-half (2 1/2) inches in diameter. 146

5. Stormwater management basins shall be designed to meet the minimum safety standards for stormwater management basins at subsection 25-29.8. b. Stormwater management measure guidelines are available in the New Jersey Stormwater Best Management Practices Manual. Other stormwater management measures may be utilized provided the design engineer demonstrates that the proposed measure and its design will accomplish the required water quantity, groundwater recharge and water quality design and performance standards established by this section. c. Manufactured treatment devices may be used to meet the requirements of this section, provided the pollutant removal rates are verified by the New Jersey Corporation for Advanced Technology and certified by the Department. (Ord. No. 2063-06 § 6) 25-29.7 Sources for Technical Guidance. a. Technical guidance for stormwater management measures can be found in the documents listed at paragraphs 1. and 2. below, which are available from Maps and Publications, Department of Environmental Protection, 428 East State Street, P.O. Box 420, Trenton, New Jersey, 08625; (609) 777-1038. 1. Guidelines for stormwater management measures are contained in the New Jersey Stormwater Best Management Practices Manual, as amended. Information is provided on stormwater management measures such as: bioretention systems, constructed stormwater wetlands, dry wells, extended detention basins, infiltration structures, manufactured treatment devices, pervious paving, sand filters, vegetative filter strips, and wet ponds. 2. The New Jersey Department of Environmental Protection Stormwater Management Facilities Maintenance Manual, as amended. b. Additional technical guidance for stormwater management measures can be obtained from the following: 1. The "Standards for Soil Erosion and Sediment Control in New Jersey" promulgated by the State Soil Conservation Committee and incorporated into N.J.A.C. 2:90. Copies of these standards may be obtained by contacting the State Soil Conservation Committee or any of the Soil Conservation Districts listed in N.J.A.C. 2:90-1.3(a)4. The location, address, and telephone number of each Soil Conservation District may be