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, 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-inch (1 ") 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 onethird (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-inch and a maximum spacing between bars offour (4) inches. In addition, the design of trash racks must comply with the requirements of Section 13-8.407B.

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 inches in diameter.

5. Stormwater management basins shall be designed to meet the minimum safety standards for stormwater management basins at Section 13-8.407.

6. Where tailwater will affect the hydraulic performance of a stormwater management measure; the Design Engineer shall include such effects in the measures design.

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 Section 13-8.403 of this ordinance.

C. Manufactured treatment devices may be used to meet the requirements of Section 13-8.403 of this ordinance, provided the pollutant removal rates are verified by the New Jersey Corporation for Advanced Technology and certified by the Department.

D. The design of stormwater conveyance systems shall incorporate the use of the curb cuts that will direct stormwater runoff into vegetated swales and other vegetated to allow the disconnection of impervious areas. This method shall be used to drain roadways, parking lots and landscaped areas.

E. Longitudinal and cross drains shall be designed to convey runoff resulting from a storm of 25-year frequency.

F. Stormwater quantities shall be calculated using the Rational Method. Rainfall intensity shall be as determined from the rainfall intensity curves for Morris County contained in the Morris County Stormwater Management Technical Guide. The minimum time of concentration shall be 10 minutes.

G. Storm sewers shall be of reinforced concrete pipe with a minimum rating of Class III or a NJDOT approved equal high-density polyethylene. Pipeline capacities shall be determined using Manning's Equation with roughness coefficients of 0.013 for concrete and 0.01 for polyethylene. Minimum pipe size shall be 15 inches.

H. Pipelines shall be placed on grades, which will assure a minimum velocity of two feet per second when flowing one-half full.

1. Manholes or inlets shall be provided at intervals not exceeding 400 feet and wherever branches are connected or changes occur in alignment or grade, excepting the first inlet in a collection system along a cartway. Alignment of pipes shall be straight between manholes and inlets. Manholes and inlet pipes shall be straight between manholes or inlets. Manholes and inlet castings shall be of cast iron construction suitable for heavy-duty highway traffic loading. Grate patterns shall be in accordance with Section 13-8.403 of this Ordinance.

J. Where storm sewers included pipelines and vegetated swales are installed in easements, said easements shall be a minimum of 20 feet in width.

K. The use of natural vegetated swales in lieu of inlets and pipes are encouraged to be used for drainage purposes.