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a. Standards for structural stormwater management measures are as follows:
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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).
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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 30-157.8d.
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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.
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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.
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5. Stormwater management basins shall be designed to meet the minimum safety standards for stormwater management basins at subsection 30-157.8.
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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 subsection 30-157.4 of this chapter.
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c. Manufactured treatment devices may be used to meet the requirements of subsection 30-157.4 of this chapter, provided the pollutant removal rates are verified by the New Jersey Corporation for Advanced Technology and certified by the Department. (Ord. No. 2006-06 § 3)
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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, New Jersey Department of Environmental Protection, 428 East State Street, P.O. Box 420, Trenton, New Jersey, 08625; Telephone (609) 777-1038.
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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: bio-retention systems, constructed stormwater wetlands, dry wells, extended detention basins, infiltration structures, manufactured treatment devices, pervious paving, sand filters, vegetative filter strips, and wet ponds.
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2. The New Jersey Department of Environmental Protection Stormwater Management Facilities Maintenance Manual, as amended.
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b. Additional technical guidance for stormwater management measures can be obtained from the following:
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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 obtained from the State Soil Conservation Committee, P.O. Box 330, Trenton, New Jersey 08625; (609) 292-5540;
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2. The Rutgers Cooperative Extension Service, 732-932-9306; and
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3. The Freehold Soil Conservation Districts, 4000 Kozlowski Road, Freehold New Jersey, 07728, (732) 683-8500. (Ord. No. 2006-06 § 3)
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a. This subsection sets forth requirements to protect public safety through the proper design and operation of stormwater management basins. This subsection applies to any new stormwater management basin.
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b. Requirements for Trash Racks, Overflow Grates and Escape Provisions.
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1. A trash rack is a device designed to catch trash and debris and prevent the clogging of outlet structures. Trash racks shall be installed at the intake to the outlet from the stormwater management basin to ensure proper functioning of the basin outlets in accordance with the following:
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(a) The trash rack shall have parallel bars, with no greater than six (6) inch spacing between the bars.
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(b) The trash rack shall be designed so as not to adversely affect the hydraulic performance of the outlet pipe or structure.
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(c) The average velocity of flow through a clean trash rack is not to exceed two and one-half (2.5) feet per second under the full range of stage and discharge. Velocity is to be computed on the basis of the net area of opening through the rack.
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(d) The trash rack shall be constructed and installed to be rigid, durable, and corrosion resistant, and shall be designed to withstand a perpendicular live loading of three hundred (300) lbs./ft. sq.
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2. An overflow grate is designed to prevent obstruction of the overflow structure. If an outlet structure has an overflow grate, such grate shall meet the following requirements:
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(a) The overflow grate shall be secured to the outlet structure but removable for emergencies and maintenance.
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(b) The overflow grate spacing shall be no less than two (2) inches across the smallest dimension.
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(c) The overflow grate shall be constructed and installed to be rigid, durable, and corrosion resistant, and shall be designed to withstand a perpendicular live loading of three hundred (300) lbs./ft. sq.
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3. For purposes of this paragraph, escape provisions means the permanent installation of ladders, steps, rungs, or other features that provide easily accessible means of egress from stormwater management basins. Stormwater management basins shall include escape provisions as follows:
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