A. 
Jurisdiction. Pursuant to N.J.S.A. 40: 27-6.2a and N.J.S.A. 40:27-6.6e all land development which will cause stormwater to drain either directly or indirectly to a County road or through any drainageway, structure, pipe, culvert or facility for which the County is responsible for the construction, maintenance or proper functioning shall provide a stormwater management plan in accordance with the standards and criteria established in this chapter.
B. 
Requirements.
(1) 
Stormwater drainage improvements shall be required to provide sufficient design and capacity to satisfactorily accommodate the anticipated impact upon a County road or County-maintained drainage facility from the increased runoff created by any land development.
(2) 
In the Pinelands area, the standards of N.J.A.C. 7:50-6, Part VIII, of the Comprehensive Management Plan for stormwater drainage improvements shall be met.
C. 
Waivers. The applicant may request a waiver from strict compliance with the stormwater management regulations and procedures herein established as outlined in § 86-310. The DRC may waive or adjust individual standards as may be reasonable and within the general purpose of this chapter.
It is not practical to show all possible stormwater design standards in this section. Therefore, standards from the following references shall be considered in the planning and design of all stormwater management systems affecting County highways, bridges, drainageways, and related structures and facilities.
A. 
Residential Site Improvement Standards of the New Jersey (Chapter 7) Administrative Code, Title 5, Chapter 21, except where modified by the County. (Note: Where reference is made to approvals by the municipal engineer, a municipal agency, municipal attorney, or similar reference, it shall mean the County Engineer, County agency, County Counsel, etc.)
B. 
Construction practices shall conform to Standards for Soil Erosion and Sediment Control in New Jersey, N.J.A.C. 2:90-1, as administered by the New Jersey Department of Agriculture.
C. 
Highway drainage structures shall be designed, where applicable, in accordance with the Design Manual-Roadway, New Jersey Department of Transportation.
D. 
Inlets, catch basins, and manholes shall be designed in accordance with the Standard Specifications for Road and Bridge Construction, New Jersey Department of Transportation.
E. 
Urban Hydrology for Small Watersheds, Technical Release No. 55 (TR-55), U.S. Department of Agriculture, Soil Conservation Service, Engineering Division.
F. 
Design and Construction of Urban Stormwater Management Systems, ASCE Manuals and Reports of Engineering Practice No. 77.
G. 
Green Infrastructure Guidance Manual for New Jersey, Rutgers Cooperative Extension Water Resources Program.
A. 
Techniques. The following techniques may be appropriately utilized regarding stormwater management:
(1) 
Detention basins.
(2) 
Perforated pipe within stone trench.
(3) 
Retention basins.
(4) 
Grassed swales and vegetative areas.
(5) 
Infiltration facilities.
(6) 
Concrete lattice block surfacing.
(7) 
Seepage pits.
(8) 
Decreased impervious area coverage.
B. 
Proposed stormwater management techniques are not limited to the ones listed above. If an alternate system is proposed, sufficient rationale for using that system shall be provided. The use of other control methods not listed above shall be subject to the review and approval by the County Engineer and DRC.
C. 
Stormwater management techniques shall be tailored to specific site characteristics, such as depth to seasonal high groundwater, soil types and topography.
A. 
A written report shall accompany the stormwater management plan and shall include the following items:
(1) 
A narrative summarizing the methods proposed to accommodate stormwater runoff to and from the site. Any impacts to a County stormwater management facility shall be addressed in this narrative.
(2) 
A summary narrative and table comparing predevelopment and post-development rates and volumes for the two-, ten-, fifty- and 100-year storm events.
(3) 
Drainage calculations for existing and proposed conditions; drainage design plans depicting existing and proposed information, and supporting documentation, such as watershed subarea data, worksheets, hydrograph data, drainage area map (on-site and off-site), stormwater facilities plans, including profile and cross section details, structure elevations, including pipe inverts (inflow and outflow), grate, spillway top of embankment, soil boring logs and locations; stormwater management basin maintenance plan narrative, construction schedule, analysis of existing County facilities to accommodate proposed development.
B. 
A downstream analysis and impact statement shall be prepared and submitted for review, if requested by the County Engineer.
A. 
Stormwater management plans and facilities shall be designed to accommodate runoff from the development of the site for the two-year, ten-year, fifty-year, and 100-year storm events so that predevelopment peak flow rates and volumes that impact on downstream properties, watercourses, and/or drainage systems are not increased.
B. 
Existing drainage problems affecting the County roads and drainage facilities shall be addressed in the proposed development area even if there is no change or a decrease in impervious cover from predevelopment and post-development.
C. 
Stormwater runoff or natural drainage water shall not be diverted as to overload existing drainage systems, cause flooding or erosion, or create the need for additional drainage facilities on other property.
D. 
Stormwater management plans shall consider the natural drainage water which originates not only within the development boundaries but which also originates from the total natural watershed. Drainage calculations shall be computed to include the entire portion of the watershed.
E. 
Stormwater management facilities designed as an infiltration basin shall provide for the bottom of the basin to be a minimum of two feet above the elevation of the seasonally high water table.
F. 
Soil borings and soil logs.
(1) 
At least one soil boring and soil log shall be provided for each stormwater management facility. All soil borings are to extend at least five feet below the bottom of the proposed stormwater management facility.
(2) 
For stormwater management facilities having a surface area greater than 1/2 acre, additional soil borings are required at a rate of one boring for every 1/2 acre.
(3) 
Soil borings shall be provided at a rate of one per 150 linear feet of swale or trench for all linear stormwater management facilities, such as stone trenches.
(4) 
The soil logs shall include the following information:
(a) 
Description of soil depth below existing surface.
(b) 
Estimated depth to seasonal high groundwater.
(c) 
Depth of groundwater, if encountered.
(d) 
Soil percolation rates.
G. 
New stormwater management basins side slopes for earthen dams, embankments or berms shall not exceed three horizontal to one vertical.
H. 
To the maximum extent practical, all stormwater management basins should have length to width ratios of at least two to one for the distance between the basin inflow and its outflow.
I. 
Stormwater management facilities where emergency overflow cannot be provided must be sized to at least accommodate the 100-year storm.
J. 
Discharge outlets from stormwater detention basins shall be designed to normally operate without manual, electric, or mechanical controls. Outlet pipes shall have a minimum diameter of 12 inches; however, outlet flow limiting devices having a minimum diameter of six inches may be incorporated into the outlet structure. Trash racks shall be installed at the intake to the outlet from the stormwater management basin if the intake has a diameter of 12 inches or greater.
K. 
Energy dissipaters shall be provided at all inflow and outflow locations to reduce water velocity and soil erosion. All pipe ends shall be designed with an appropriate headwall.
L. 
Positive outflow to an existing drainage system or stream shall be provided for all stormwater detention and retention facilities which may affect County roads or drainage. Such outflow shall not be directed across pedestrian walkways or roadway border areas by overlay and flow.
M. 
No pipe size in the County storm drainage system shall be less than 15 inches in diameter.
N. 
Materials used in construction of storm sewers within existing or proposed County rights-of-way shall be reinforced concrete pipe, ductile iron, or, when approved by the County Engineer, corrugated polyethylene, and corrugated aluminum.
O. 
Construction of storm sewers within the County right-of-way should not be laid directly beneath the curbline when extending sewers parallel with the roadway in order to avoid, if possible, potential curb or gutter settlement as well as potential shallow cover concerns when the curb is installed.
P. 
Appropriate soil erosion and sediment control measures shall be incorporated into the design of the stormwater management facilities.
Q. 
All development, except lands within the Pinelands Area, shall adhere to requirements of the New Jersey Department of Environmental Protection regarding wetland areas and their related buffer and/or transition areas as regulated under the Wetlands Act of 1970 and the Freshwater Wetlands Protection Act.[1] Development within the Pinelands Area shall adhere to the requirements of the Pinelands Commission.
[1]
Editor's Note: See N.J.S.A. 13:9A-1 et seq., and N.J.S.A. 13:9B-1 et seq., respectively.
In addition to the standards of the County, the stormwater management facilities in the Pinelands Area shall be designed to comply with the requirements and standards of the New Jersey Pinelands Comprehensive Management Plan, as administered by the Pinelands Commission.
A. 
Drainage calculations shall be provided which demonstrate conformance with the standards of N.J.A.C. 7:50-6.84 of the Comprehensive Management Plan and describe any deviations from County standards.
B. 
In any Pinelands Area, no development within wetlands or within 300 feet of wetlands is permitted unless the developer can demonstrate that the development will not result in an adverse impact on wetland areas as determined by the Pinelands Commission.
A. 
Stormwater management shall provide for the control of a water quality design storm. The water quality design storm shall be defined as the one-year frequency S.C.S. Type III, twenty-four-hour storm or 1.25 inches of rainfall falling uniformly in two hours.
B. 
In addition to addressing water quantity generated by development, a stormwater management system shall also prevent, to the greatest extent feasible, an increase in nonpoint pollution.
C. 
The water quality storm shall be controlled by best management practices. These include, but are not limited to, the following:
(1) 
In dry detention basins serving residential development, provisions shall be made to ensure that the runoff from the water quality design storm is retained, such that not more than 90% will be evacuated prior to 18 hours.
(2) 
In dry detention basins serving nonresidential development, provisions shall be made to ensure that the runoff from the water quality design storm is retained, such that not more than 90% will be evacuated prior to 36 hours.
(3) 
Retention time shall be considered a brim-drawdown time and therefore shall begin at the time of peak storage. The retention time shall be reduced in any case that would require an outlet size diameter of three inches or less. (Therefore, three-inch diameter orifices shall be the minimum allowed. The minimum is only for water quality outlets.)
(4) 
In permanent ponds or wet basins, the volume of permanent water is at least three times the volume of runoff produced by the water quality design storm.
(5) 
Infiltration practices, such as dry wells, infiltration or retention basins, infiltration trenches and buffer strips, may be used to satisfy this requirement, provided that they produce zero runoff from the water quality design storm and allow for complete infiltration within 72 hours.
Prior to final approval being issued, the applicant shall provide the following:
A. 
A construction cost estimate for the stormwater management facilities approved by the DRC. If additional construction is proposed, as part of the approval process, these costs shall be combined into one cost estimate.
B. 
A performance guarantee in the amount of the cost estimate approved by the County.
A. 
The County Engineer shall inspect all stormwater management facilities approved by the DRC and to be accepted and maintained by the County or covered under a County drainage covenant.
B. 
The County reserves the right to inspect all stormwater management facilities that will drain stormwater to a County-owned right-of-way or facility owned or maintained by the County.
C. 
For all stormwater management facilities approved by the DRC and to be accepted and maintained by the County or covered under a County drainage covenant, the applicant's engineer shall provide a certification that the facility has been built in accordance with the plans and specifications of the approved plans and as-built construction plans for the drainage facility have been submitted.
A. 
A stormwater maintenance schedule shall be required, as part of any subdivision or site plan application, which is subject to review and approval by the DRC. At a minimum, the stormwater maintenance schedule shall include the following:
(1) 
The party responsible for the maintenance of the stormwater facility.
(2) 
Type and frequency of maintenance required. All basins shall be cleaned initially upon stabilization of landscaped areas. Cleaning shall consist of the dredging and removal of all silts and fines from the bottom and side slopes of the basin.
(3) 
Equipment required for the maintenance of said facility.
(4) 
Cost of such maintenance.
B. 
The construction schedule for the completion of the stormwater management basins and the development shall include phases which address protection of the basin from erosion and sediment generated during construction of the development, as well as the removal of sediment from the basin and other structures during construction and after development.
C. 
A clear accessway of 15 feet shall be provided to all stormwater facilities (basins) for the purpose of assuring vehicular access for maintenance activities and shall be at a slope no greater than 10:1.
D. 
In the event that the stormwater management system becomes a danger to the public health or safety, or if it is in need of maintenance, the County shall notify, in writing, the responsible party by certified mail. The responsible party shall have 14 days to perform such maintenance and repair the facility subject to the review and approval of the County Engineer. If the responsible party either refuses to repair or conducts such repair in a manner unacceptable to the County Engineer, the County may immediately proceed with the repair or maintenance of the facility and bill the costs thereof to the responsible party.
E. 
For applications in the Pinelands Area, the stormwater maintenance requirements of N.J.A.C. 7:50-6.84(a)6vii of the Comprehensive Management Plan shall also apply.
A drainage covenant may be required by the DRC if a County road or drainage facility is incorporated into the stormwater management plan of a site plan or subdivision application. The drainage covenant shall conform to the Declaration of Covenants and Restrictions for Drainage Structures found on the County website.
A. 
County right-of-way. No proposed drainage facilities, or parts thereof, shall be located within either an existing or proposed County right-of-way or easement without the permission of the County Engineer.
B. 
Drainage facilities owned and maintained by the County. Prior to the utilization of a County-owned and -maintained drainage facility, applicants must receive approval from the DRC, with the recommendation of the County Engineer. The applicant's request to use or expand use of a County-owned or -maintained drainage facility must be made in writing addressed to the County Engineer.
A. 
A drainage easement may be required to permit access to operate and maintain a stormwater facility.
B. 
All drainage easements shall be clearly identified and be labeled with bearings and distances prepared by a professional land surveyor. The drainage easement shall be a minimum of 20 feet wide.
A. 
The following information shall be submitted for developments that utilize a County drainage facility to accommodate site generated runoff.
(1) 
The existing and proposed flow and volume discharging into the County-owned and -maintained drainage facility.
(2) 
A determination as to whether or not the existing County drainage facility would need to be enlarged.
(3) 
The rationale for proposed use of the County facility.
(4) 
Identification of all permits required as a result of the proposed utilization. The applicant shall be responsible for obtaining all necessary permits, prior to receiving a final approval by the DRC.
(5) 
Signed and sealed design plans prepared by a professional engineer licensed in the State of New Jersey, and signed and sealed survey plan by a New Jersey professional land surveyor of the property to be improved.
(6) 
An engineering cost estimate in accordance with § 86-309 of this chapter.
B. 
In determining whether or not to permit the utilization of a County-owned and -maintained drainage facility, the County Engineer shall consider existing and proposed flows, condition and capacity of the existing system, existing drainage problems, site topography, soils, depth to seasonal high water table, municipal requirements, and the condition and capacity of the existing or proposed County drainage facility.
A. 
In the event that the applicant proposes to discharge, by pipe, swale, sheet flow or any other means, stormwater from the development site to, over, or through any other off-site point, then it shall be the responsibility of the applicant to demonstrate that such stormwater discharges are consistent with the rate and general directions of predevelopment natural stormwater flows.
B. 
All easements deemed necessary by the County to utilize off-site property for stormwater discharges must be obtained by the applicant.
A. 
Where a proposed development affects an existing bridge or culvert and the existing structure has adequate waterway area and is not scheduled for replacement, the applicant shall widen the culvert to the width of the proposed right-of-way and bridge to planned curb-to-curb pavement width plus an additional 10 feet for roadside border area.
B. 
If the culvert or bridge is scheduled for early replacement or is of such construction that widening is impractical in the opinion of the County Engineer, the applicant shall design and construct a new schedule in accordance with Article 600 of this chapter.
C. 
Plans for proposed work shall have the approval of the County Engineer and from all other agencies having jurisdictional review authority. The County Engineer upon approving plans and reviewing the design engineer's construction cost estimate, will set the amount of a guarantee to be posted with the County in order to ensure the satisfactory completion of work.
D. 
Material testing shall be provided by the applicant during construction, and results shall be supplied to the County Engineer from a certified testing laboratory within two weeks after facility installation and prior to release of the performance guarantee.
E. 
Upon acceptance of the improvement by the County Engineer and the posting of a two-year maintenance guaranty, the performance guaranty may be released.