No application for development shall be approved unless the Township Engineer has certified to the approving authority in writing that:
A. 
The applicant has provided the Township Engineer with sufficient information for him to determine whether or not the proposed development will conform to Township runoff standards, runoff control details and stormwater detention facility design criteria.
B. 
In the judgment of the Township Engineer, the proposed development will substantially conform to these standards and design criteria set forth herein.
A. 
Retention and detention basins as may be required for surface runoff and drainage control shall be located on-site and within the zoning district permitting that use, subject to the requirements outlined herein. Such basins shall be considered accessory uses and also subject to the conditions of § 170-159 of this chapter.
B. 
Such stormwater control improvements may be located within the setback lines of the area to be improved, excluding landscape transition buffers or landscape strips as may be required by Part 2, Zoning.
Where it can be demonstrated, at the time of Planning Board review, that such on-site basin location within the zoning district permitting that use is impractical due to engineering feasibility factors, then the Planning Board may permit such basins to be located off-tract and/or out of the zoning district, provided that the following requirements are met:
A. 
All of the conditions noted in this article are met in addition to § 170-159 of this chapter.
B. 
The location of the basin does not hinder or discourage the appropriate development and use of the property on which it is located or the use of adjacent land and buildings.
C. 
Permanent access or easement to the basin for maintenance purposes shall be provided.
D. 
Utilization of other nearby off-tract basin facilities is not feasible or practicable as determined by the Township Engineer.
Basins other than those providing long-term water retention, such as at a recreational or irrigation lake or basin facility serving three or more properties, shall be designed to be dewatered with the side slopes and floor of such basins to be sodded. Where dewatering is not practical, then areas adjacent to such basins shall contain protective landscaping (e.g., thorny, decorative shrubs), arranged so as to restrict access to its edge. Where basins in general are to be located in parking lots or areas adjacent to pedestrian or vehicular traffic, dense plantings of shrubs to act as barriers and adequate low-level lighting for safety precautions shall be required.
A. 
No land area in the Township shall be developed so that:
(1) 
The maximum rate of stormwater runoff from the area from any storm up to and including the one-hundred-year-probability storm (which shall be known as the "design storm") is increased over what occurs there under existing conditions. The one-hundred-year-probability, twenty-four-hour, Type II storm shall be as defined by publications of the Soil Conservation Service, or shall be a one-hundred-year probability storm as defined by publications of the Department of Environmental Protection for the size of site in question.
(2) 
The drainage of adjacent areas is adversely affected.
(3) 
Soil erosion during and after development is increased over what naturally occurs there.
(4) 
Soil absorption and groundwater recharge capacity of the area is decreased below what occurs under existing conditions.
(5) 
The natural drainage pattern of the area is significantly altered.
B. 
Provisions should be made for retention of runoff from small storms long enough for settlement of particulates. Specifically, the stored runoff from 1 1/4 inches of rainfall occurring in two hours must allow only 90% to be evacuated from the detention facility during 36 hours, or during 18 hours in the case of dry basins in residential areas. This requirement for retention may be waived for residential areas where runoff is passed in sheet flow over 30 feet of lawn or leaf-mulch area, and the full extent of retention will not be required where this would require outlets less than three inches in diameter.
In order to duplicate as nearly as possible natural drainage conditions, regulation and control of stormwater runoff and erosion for any land area to be developed shall be through on-site water detention and/or ground absorption systems which include, but are not limited to, the following:
A. 
Detention areas which may be depressions in parking areas, excavated basins, basins created through use of curbs, stabilized earth berms or dikes, or any other form of grading which serves to temporarily impound and store waters.
B. 
Rooftop storage, through temporary impoundment and storage of stormwater, on flat or slightly pitched building rooftops by use of drain outlets which restrict the stormwater runoff from the roof surface.
C. 
Drywells or leaching basins which control stormwater runoff through ground absorption and temporary storage.
D. 
Porous pavement or gravel, which preserves the natural ground absorption capacity of a site and provides a subsurface reservoir for temporary storage of stormwater.
E. 
Any system of porous media, such as gravel trenches drained by porous wall or perforated pipe, which temporarily store and dissipate stormwater through ground absorption.
F. 
Any combination of the above mentioned techniques which serve to limit stormwater runoff from a given site to what presently occurs there.
G. 
Preservation of natural vegetation.
A. 
Stormwater detention facilities shall be designed to contain an amount equal to the increase in volume of runoff which would result from development of any site. The volume of runoff shall be computed on the basis of the one-hundred-year-probability storm, as previously defined. The difference between the runoff from one-hundred-year storm after development and the runoff from a two-year storm prior to development shall be known as the "runoff excess."
B. 
The runoff shall be computed for each site using accepted, published runoff coefficients such as found in Urban Hydrology for Small Watershed, Technical Release No. 55 Engineering Division, Soil Conservation Service, United States Department of Agriculture, January 1977, and as may be modified by the Township Engineer. The range of coefficients for each land use and surface type reflects differences in land slope, intensity of development, amount of impervious surface and degree of ground saturation due to antecedent precipitation.
C. 
The runoff shall be determined for each site for both existing and proposed conditions and the difference in the two, or runoff excess, shall be used to determine the capacity of the stormwater detention facilities. If any such facility will contain water under normal conditions, the amount so contained shall not be counted in calculating the capacity required for the detention of water for the design storm.
D. 
In the case of detention facilities utilizing porous media for ground absorption, such as drywell, porous pavement or the like, the volume of the porous media above the water table shall be large enough to contain the total volume of runoff excess within the voids. Ground absorption systems shall be used only where the infiltration rate of the receiving soil is acceptable as determined by percolation tests and soil borings, or as determined by the Township Engineer. Provisions shall be made to contain overflow on such systems on-site or to surface drain the overflow in such a way as not to adversely affect any other property.
E. 
If detention facilities utilizing surface impoundment, such as detention basins or rooftop storage, are used, sufficient volume to fully contain the total volume of runoff excess shall be provided. The outlets of such facilities shall discharge in such a way as not to adversely affect any other property. If rooftop storage is proposed, the weight of the impounded water on the roof shall be accounted for in the structural design of the building, and the roof shall be designed to provide maximum protection against leakage. If berms or dikes are used to create the impounding area, they shall be adequately stabilized and the slopes protected with vegetative cover, paving or rip-rap to protect against failure or breathing.
F. 
If a combination of different stormwater detention techniques is used, combined volume of the systems shall be large enough to fully contain the total volume of runoff excess.
G. 
Stormwater detention facilities shall be constantly maintained by the owner to ensure continual functioning of the systems at design capacity and to prevent the health hazards associated with debris buildup and stagnant water. In no case shall water be allowed to remain in any facility long enough to constitute a mosquito-breeding, disease or any other type of health problem, unless approved as a multifunction facility to include water, such as a pond. If the land or stormwater detention facility or facilities are proposed to be dedicated to the Township and said dedication is accepted by the Township, the procedures for the construction, dedication and acceptance and maintenance of such facilities set forth herein, including but not limited to performance and maintenance bonds, inspections, etc., shall govern.
H. 
Detention and sediment and erosion control facilities shall be designed in conformance with the Standards for Soil Erosion and Sediment Control in New Jersey of the New Jersey State Soil Conservation Committee, as approved by the Township Engineer or the Salem County Soil Conservation District under agreement, except where the Township Engineer has determined that conditions peculiar to a certain site warrant exception.
I. 
Sediment and erosion control measures shall be installed prior to any other site development, shall apply to all aspects of the proposed development, and shall be in operation during all stages of development. Increased runoff and sediment, resulting from modified soil and surface conditions caused by the proposed development, shall be minimized and where possible, retained on-site.
J. 
For each detention basin, an emergency spillway shall be provided which will accommodate flows from storms in excess of the design storm. Outlets shall be designed so as to reduce the maximum rate of outflow from the design storm after development to a rate not in excess of that which would have occurred prior to development as required by § 170-160A(1) above, both for the peak instantaneous flow and the peak hourly flow, and to provide for retention of runoff from small storms as required by § 170-160B above. Outlets shall effect the maximum practicable degree of detention of runoff from storms of intermediate size. If an affirmative showing is made that storage in an amount less than the runoff excess will satisfy requirements of § 170-160 for both the design storm and for storms respectively 1/4, 1/2, 3/4 of that amount of rainfall, then that reduced amount of storage will be sufficient to satisfy the requirements of this chapter. In making this determination, all lands in the site shall be assumed, prior to development, to be in good condition (if the lands are pastures, lawns or parks) with good cover if the lands are woods, or with conservation treatment (if the land is cultivated) regardless of conditions existing at the time of computation.
K. 
Outlet waters from the site or the detention facility shall be discharged at such locations and velocities as not to cause additional erosion, or to create additional channels below the development.
Prior to the granting of any site development approval, the applicant may be required to enter into an agreement with the Township, in form satisfactory to the Township Attorney, requiring the installation and maintenance by the applicant and the applicant's successors in interest, of such improvements on or to the site or imposing such limitations upon the development thereof, as are deemed necessary by the Planning Board for implementing the standards and criteria set forth in this chapter, providing that the municipality may cause such improvements to be installed or maintained and developments in violation of such limitations to be corrected at the expense of the applicant or the applicant's successors in interest, if they shall fail to do so, and granting to the municipality such rights and easements as shall be reasonably required for access by the municipality to such improvements and developments for such purposes. The agreement shall also provide for inspection annually and after each major flood by the Township Engineer and by another qualified engineer acceptable to the Township Engineer, at the expense of the applicant and the applicant's successors in interest, and for the undertaking by the applicant and successors of such corrective measures as are shown by such inspection to be required for the proper functioning of the facilities.
Such improvements and developments on the site, during and upon completion of their construction, shall be subject to inspection and approval by the Township Engineer, who shall be notified by the applicant at least 24 hours prior to the start of construction. No underground installation shall be covered until inspected and approved. Approval or reasons for withholding approval shall be given promptly, and in any event within 45 days after inspection. If work proceeds without such approval or not in compliance therewith, the Township Engineer, in addition to any other remedies available to the municipality, may issue an order requiring immediate cessation of the affected work and prohibiting resumption thereof until approval is obtained or noncompliance corrected.
Prior to the acceptance by the Township of any stormwater facilities, the developer's engineer shall certify that said facilities were constructed in accordance with the approved plan.
A. 
The provision of separate detention facilities for a number of single sites is generally more expensive and more difficult to maintain than provision of joint facilities each serving a number of sites. In such cases, a properly planned staged plan and program of detention facilities may be approved by special ordinance; and, in such a case, compliance with detention requirements for areas first developed may be postponed at early stages while preliminary work is being undertaken, sites acquired and construction funds accumulated.
B. 
In such a case, an initial money contribution will be levied upon each developer, proportionate to the runoff excess of his proposed development. Such funds will be held in escrow for use in carrying out the joint plan. Construction and maintenance responsibility for the joint facilities will be determined and specified as part of the plan.