Design Storm Frequency for Closed Conduits. Ten years, or if the above results in a conduit size at least equivalent to a sixty (60") inch reinforced concrete pipe — 25 years.

Design Storm Frequency for Open Channels. Ten years, or if the tributary area exceeds 320 acres — 25 years.

Run-off Calculations. Run-off determination should be made using the rational formula or, in unusual cases, other methods with the prior approval of the Planning Board. Upstream areas should be considered based on the full development potential according to current zoning or current use, whichever is most restrictive. Run-off coefficients used should generally fall in the following ranges classification: fully developed public parks, open space and land conservation range of coefficient 0.15-0.30; low density residential 0.30-0.45; minimum density residential 0.40-0.60; high density residential 0.55-0.70; commercial and industrial 0.60-0.90; pavements, roadways, shoulders 1.00.

Velocity Restrictions in General; Closed Conduit. Velocity in closed conduit at design flow should be at least two and five-tenths (2.5') feet per second but not more than the velocity which would cause erosion damage to the conduit.

Velocity Restrictions in General; Open Channel. Velocity in open channel at design flow shall be not less than one-half (1/2') foot per second (0.5 FPS) and not greater than the velocity which will begin to cause erosion or scouring of the channel. Sufficient soil testing to determine the character of the channel shall be made by the developer and shall be made available to the Planning Board at the time of drainage review.

Design Formula and Friction Factors. The Manning Formula will be used by the Borough Engineer to review the adequacy of proposed drainage facilities. Other formula may be used in particular cases with the previous agreement of the Planning Board. A friction factor ("n") of 0.012 will be used for non-porous concrete pipe; a factor of 0.024 will be used for fully coated corrugated metal pipe. Commensurate factors will be used for other pipe types or shapes. A friction factor ("n") not less than 0.012 will be used for fully lined concrete channels: a factor not less than 0.025 will be used for good earth channels and a factor of not less than 0.05 will be used for fair to poor natural streams and water courses. Commensurate factors will be used for other channel types.

All drainage facilities carrying run-off from tributary areas larger than 1/2 square mile or 320 acres must be a stream encroachment approval of the New Jersey Department of Environmental Protection, Division of Water Resources. Evidence of such approval shall be required to be submitted prior to the final approval of the site plan.

All non-pipe culverts under roadways shall be designed for AASHO H20-44 loading. All culverts of any type shall be carried to the roadway right-of-way and shall terminate with headwalls or other approved end treatment. All conduits terminating or beginning in open channels shall be provided with headwalls or other appropriate end treatment.

Responsibility for Design. Within the criteria established by and subject to the review and approval of the Planning Board, all designs of a site are the responsibility of the developer, and he shall be responsible for and bear the entire cost of any and all investigations, tests, reports, surveys, samples, calculations, designs, researches or any other necessary to the completion of the site design. The standard set in this ordinance shall be taken to be the minimum necessary to meet its purposes as set forth elsewhere herein. The responsibility of the Planning Board shall be to see that these minimum standards are followed and, in those cases not covered by these standards sufficient precautions are taken to assure that the eventual site design is conducive to the implementation of the purposes of this section. The Planning Board may employ professionals in various disciplines to advise and assist them in their determinations. Any decision of the Planning Board regarding the suitability of sufficiency of any design proposal, taken upon advice of their professional and subject to the provisions of this section shall be deemed conclusive.

Design Data. To properly execute the design of the site, it is anticipated that the developer will obtain or cause to be obtained certain design data including, but not limited to, soil test and analyses, traffic studies and traffic projections, surveys, reports and similar design data. Any and all data obtained by the developer, or by others retained by him to complete the design of the site, shall be made available to the Planning Board's professional consultants, for the purposes of reviewing the proposed site design. Should the Planning Board feel the design data submitted are not sufficient for the purposes of completing a full review of the site proposal, they may request the applicant provide such additional information as is deemed necessary. Until the applicant supplies such information, no submission under the provisions of this section shall be termed complete. Nothing contained herein shall be interpreted to prevent the Planning Board from making or causing to be made such independent studies, calculations or other undertakings as they deem necessary in view of any proposal.

Design Standards. When a developer determines that it will be necessary to utilize design standards in addition to those minimum requirements established herein, he is advised to consult the Planning Board, prior to his beginning the detailed sign, for review and approval of his proposed design standards. Standards utilized should be accepted national standards, commonly used in this area. All such design standards shall be approved by the Planning Board Engineer.