No application for development shall be approved unless the Township Engineering Department has certified to the approving authority in writing that:
A. 
The applicant has provided the Engineering Department with sufficient information for it to determine whether or not the proposed development will conform to Township runoff standards, runoff control details and stormwater detention facility design criteria.[1]
[1]
Editor's Note: Ordinance No. 91-33, adopted 11-18-1991, provided that drainage calculations should be added to completeness checklists for preliminary subdivisions and site plans.
B. 
In the judgment of the Township Engineer the proposed development will substantially conform to the standards and design criteria set forth in this article.
[Amended 11-18-1991 by Ord. No. 91-33]
No land area in the Township shall be developed so that:
A. 
The drainage of any adjacent area is adversely affected.
B. 
The natural drainage pattern of the area is significantly altered.
C. 
Soil erosion during and after development is increased over the natural erosion rate.
D. 
Any downstream area is subjected to increase in flooding or erosion.
In order to duplicate as nearly as possible natural drainage conditions, the 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 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 water.
[Amended 11-18-1991 by Ord. No. 91-33]
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. 
Dry wells or leaching basins which control stormwater runoff through ground absorption and temporary storage.
D. 
Porous asphaltic pavement, 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 stores and dissipates stormwater through ground absorption.
F. 
Any combination of the abovementioned techniques which serves to limit stormwater runoff from a given site to conform to the requirements of § 126-280, Runoff standards.
[Amended 11-18-1991 by Ord. No. 91-33]
G. 
Preservation of natural vegetation.
H. 
Plantings and trees shall not be used in detention basins.
[Added 11-18-1991 by Ord. No. 91-33]
[Amended 11-18-1991 by Ord. No. 91-33]
A. 
Existing stormwater runoff and proposed inflow hydrographs shall be determined by the United States Department of Agriculture, Soil Conservation Service, Technical Release No. 55, Urban Hydrology for Small Watersheds (TR-55) method, as amended, by the Handbook for Stormwater Detention Basins, Somerset County, New Jersey, and the most recent addendum of each publication, or as modified by the Township Engineer.
B. 
Existing and proposed peak stormwater runoff rates shall be determined by the method specified above, for the one- , ten-and one-hundred-year design storms. The existing and proposed peak flow shall be compared for each storm so that conformance with § 126-280, Runoff standards, may be determined by the Township Engineer.
C. 
Hydrographs for storms other than the one , ten- and one hundred-year design storms and existing and/or proposed conditions may be required by the Township or other concerned agencies.
D. 
If the conditions of § 126-280, Runoff standards, are not met by the proposed condition, on-site stormwater detention and/or ground absorption shall be provided to create conditions which do comply. If a regional detention facility is currently available and if the Township Engineer approves, the developer may be allowed to make a contribution to the regional facility instead of constructing a basin on site.
E. 
Detention basin routings for the one- , ten- and one-hundred-year design storms shall be provided along with detention basin plans and performance statistics. Routings for other design storms may also be required by the Township.
F. 
Copies of calculations required for other concerned agencies shall also be provided to the Township.
G. 
Berms and dikes used to create impoundment areas shall be adequately stabilized and the slopes protected against failure or breaching. The control structure design and berm core materials shall be chosen to prevent seepage through the berm. Detention basin berms shall be designed to comply with applicable New Jersey Department of Environmental Protection and Soil Conservation Service regulations and the Somerset County Handbook for Stormwater Detention Basins.
H. 
Minimum slopes within detention basins shall be 2% for vegetated areas and swales. A minimum slope of 1% shall be allowed for smooth, impervious low flow channels.
I. 
Outfalls from detention/retention basin shall design to be stable and not to create conditions which violate § 126-280, Runoff standards.
J. 
Detention/retention basins should be situated on the site so as to naturally intercept the runoff for the one-hundred-year Somerset TR 55 storm. If the basin cannot be situated to naturally intercept overflow from the storm sewer system, then the portions of the storm sewer system necessary to intercept the storm runoff prior to its leaving the site must be able to convey the one-hundred-year Somerset County TR-55 storm to the basin.
K. 
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.
L. 
Retention basins shall be designed to maintain a minimum water level of three feet year round.
M. 
Seepage pits should be designed to contain 85% of the runoff volume of the developed one-hundred-year design storm. The alternative shall be to design the seepage pit as a detention basin with the percolation as the outflow control. The developed one-hundred-year storm hydrograph shall be used for this design.
N. 
Ground absorption systems shall only be used 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.
O. 
The use of underground detention for public facilities is discouraged for reasons of maintenance. If, in the opinion of the Township Engineer, there is not a viable alternative to an underground facility, it shall be incumbent on the applicant to provide a design which is maintainable. Such systems must have access manholes with rungs at all junction and pipe ends; be constructed of durable materials; have sufficient inside dimensions to allow for a person to walk (60 inches high minimum); and have a minimum pitch of 1%.
P. 
Underground detention on commercial sites must also be designed for ease of maintenance, but the physical requirements will be reviewed individually. The plan shall include a maintenance schedule acceptable to the Township Engineer for the owner. Deviation from the schedule will be considered a variation from the approval site plan. (See §§ 126-109, 126-113 and 126-115.)
Q. 
Provisions shall be made to provide for emergency overflow. Overflow shall be contained or directed such that no adverse conditions are created on site and that the conditions of § 126-280, Runoff standards, are not violated.
R. 
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 Council, the procedures for the construction, dedication and acceptance and maintenance of such facilities set forth in Part 9, Subdivisions, of this chapter, including but not limited to performance and maintenance bonds, inspections, etc., shall govern.
S. 
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 Commission as approved by the Township Engineer or the Somerset-Union Soil Conservation District under agreement, except where the Township Engineer has determined that conditions peculiar to a certain site warrant exception.
T. 
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.
[Added 4-4-2005 by Ord. No. 05-12]
Landscaping design for stormwater facilities shall utilize the plant selections and designs in accordance with New Jersey Stormwater Best Management Practices Manual, Chapter 7. Any departure from the species/designs identified in Chapter 7 will not be accepted unless there is a written request for such departure, which characterizes the unique circumstances that necessitate an alternate approach. The Township reserves the right to select species from Chapter 7 that will require minimal maintenance and that will create minimal vegetative litter that might otherwise clog the drainageways and outlet structures.
Prior to the granting of any site development approval, the applicant may be required to enter into an agreement with the municipality, in form satisfactory to the Municipal 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 Part 11, provided 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 or 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 or by another qualified engineer acceptable to 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.