An ordinance of spring lake heights borough, county of monmouth, state of new jersey enacting chapter 22-530 "stormwater control"," to the borough of spring lake heights land use regulations




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НазваниеAn ordinance of spring lake heights borough, county of monmouth, state of new jersey enacting chapter 22-530 "stormwater control"," to the borough of spring lake heights land use regulations
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§22-530.4: Calculation of Stormwater Runoff and Groundwater Recharge

A. Stormwater runoff shall be calculated in accordance with the following:

1. The design engineer shall calculate runoff using one of the following methods:

  1. The USDA Natural Resources Conservation Service (NRCS) methodology, including the NRCS Runoff Equation and Dimensionless Unit Hydrograph, as described in the NRCS National Engineering Handbook Section 4 – Hydrology and Technical Release 55 – Urban Hydrology for Small Watersheds; or

  1. The Rational Method for peak flow and the Modified Rational Method for hydrograph computations.

For the purpose of calculating runoff coefficients and groundwater recharge, there is a presumption that the pre-construction condition of a site or portion thereof is a wooded land use with good hydrologic condition. The term "runoff coefficient" applies to both the NRCS methodology at §22-530.4 (A)(1)(a) and the Rational and Modified Rational Methods at Section §22-530.4 (A)(1)(b). A runoff coefficient or a groundwater recharge land cover for an existing condition may be used on all or a portion of the site if the design engineer verifies that the hydrologic condition has existed on the site or portion of the site for at least five years without interruption prior to the time of application. If more than one land cover have existed on the site during the five years immediately prior to the time of application, the land cover with the lowest runoff potential shall be used for the computations. In addition, there is the presumption that the site is in good hydrologic condition (if the land use type is pasture, lawn, or park), with good cover (if the land use type is woods), or with good hydrologic condition and conservation treatment (if the land use type is cultivation).

  1. In computing pre-construction stormwater runoff, the design engineer shall account for all significant land features and structures, such as ponds, wetlands, depressions, hedgerows, or culverts, that may reduce pre-construction stormwater runoff rates and volumes.

  2. In computing stormwater runoff from all design storms, the design engineer shall consider the relative stormwater runoff rates and/or volumes of pervious and impervious surfaces separately to accurately compute the rates and volume of stormwater runoff from the site. To calculate runoff from unconnected impervious cover, urban impervious area modifications as described in the NRCS Technical Release 55 – Urban Hydrology for Small Watersheds and other methods may be employed.

  1. If the invert of the outlet structure of a stormwater management measure is below the flood hazard design flood elevation as defined at N.J.A.C. 7:13, the design engineer shall take into account the effects of tailwater in the design of structural stormwater management measures.

  1. Groundwater recharge may be calculated in accordance with the following:

1. The New Jersey Geological Survey Report GSR-32 A Method for Evaluating Ground-Water Recharge Areas in New Jersey, incorporated herein by reference as amended and supplemented. Information regarding the methodology is available from the New Jersey Stormwater Best Management Practices Manual; at http://www.state.nj.us/dep/njgs/; or at New Jersey Geological Survey, 29 Arctic Parkway, P.O. Box 427 Trenton, New Jersey 08625-0427; (609) 984-6587.

  1. Design of stormwater conduit systems shall utilize the Sandy Hook, 25-year rainfall. §22-530.5: Standards for Structural Stormwater Management Measures

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 one-third (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 of six inches. In addition, the design of trash racks must comply with the requirements of §22-530.7 (B).

  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.

  1. 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.

  2. Stormwater management basins shall be designed to meet the minimum safety standards for stormwater management basins at §22-530.7.

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 §22-530.3 of this ordinance.

C.Manufactured treatment devices may be used to meet the requirements of §22-530.3 of this ordinance, provided the pollutant removal rates are verified by the New Jersey Corporation for Advanced Technology and certified by the Department.

§22-530.6 Sources for Technical Guidance

  1. Technical guidance for stormwater management measures can be found in the documents listed at 1 and 2 below, which are available from Maps and Publications, New Jersey Department of Environmental Protection, 428 East State Street, P.O. Box 420, Trenton, New Jersey, 08625; telephone (609) 777-1038.

1 Guidelines for stormwater management measures are contained in the New Jersey Stormwater Best Management Practices Manual, as amended. Information is provided on stormwater management measures such as: bioretention systems, constructed stormwater wetlands, dry wells, extended detention basins, infiltration structures, manufactured treatment devices, pervious paving, sand filters, vegetative filter strips, and wet ponds.

2. The New Jersey Department of Environmental Protection Stormwater Management Facilities Maintenance Manual, as amended.

  1. Additional technical guidance for stormwater management measures can be obtained from the following:

1. The "Standards for Soil Erosion and Sediment Control in New Jersey" promulgated by the State Soil Conservation Committee and incorporated into N.J.A.C. 2:90. Copies of these standards may be obtained by contacting the State Soil Conservation Committee or any of the Soil Conservation Districts listed in N.J.A.C. 2:90-1.3(a)4. The location, address, and telephone number of each Soil Conservation District may be obtained from the State Soil Conservation Committee, P.O. Box 330, Trenton, New Jersey 08625; (609) 292-5540;

§22-530.7: Safety Standards for Stormwater Management Basins

  1. This section sets forth requirements to protect public safety through the proper design and operation of stormwater management basins. This section applies to any new stormwater management basin.

  2. Requirements for Trash Racks, Overflow Grates and Escape Provisions

1. A trash rack is a device designed to catch trash and debris and prevent the clogging of outlet structures. Trash racks shall be installed at the intake to the outlet from the stormwater management basin to ensure proper functioning of the basin outlets in accordance with the following:

  1. The trash rack shall have parallel bars, with no greater than six inch spacing between the bars.

  2. The trash rack shall be designed so as not to adversely affect the hydraulic performance of the outlet pipe or structure.

  1. The average velocity of flow through a clean trash rack is not to exceed 2.5 feet per second under the full range of stage and discharge. Velocity is to be computed on the basis of the net area of opening through the rack.

  2. The trash rack shall be constructed and installed to be rigid, durable, and corrosion resistant, and shall be designed to withstand a perpendicular live loading of 300 lbs/ft sq.

2. An overflow grate is designed to prevent obstruction of the overflow structure. If an outlet structure has an overflow grate, such grate shall meet the following requirements:

  1. The overflow grate shall be secured to the outlet structure but removable for emergencies and maintenance.

  2. The overflow grate spacing shall be no less than two inches across the smallest dimension.

  3. The overflow grate shall be constructed and installed to be rigid, durable, and corrosion resistant, and shall be designed to withstand a perpendicular live loading of 300 lbs./ft sq.

3. For purposes of this paragraph, escape provisions means the permanent installation of ladders, steps, rungs, or other features that provide easily accessible means of egress from stormwater management basins. Stormwater management basins shall include escape provisions as follows:

a. If a stormwater management basin has an outlet structure, escape provisions shall be incorporated in or on the structure. With the prior approval of the reviewing agency identified in §22-530.7(C) a free-standing outlet structure may be exempted from this requirement.

  1. Safety ledges shall be constructed on the slopes of all new stormwater management basins having a permanent pool of water deeper than two and one-half feet. Such safety ledges shall be comprised of two steps. Each step shall be four to six feet in width. One step shall be located approximately two and one-half feet below the permanent water surface, and the second step shall be located one to one and one-half feet above the permanent water surface. See §22-530.7(D) for an illustration of safety ledges in a stormwater management basin.

  2. In new stormwater management basins, the maximum interior slope for an earthen dam, embankment, or berm shall not be steeper than 3 horizontal to 1 vertical.

  1. Variance or Exemption from Safety Standards

1. A variance or exemption from the safety standards for stormwater management basins may be granted only upon a written finding by the appropriate reviewing agency (municipality, county or Department) that the variance or exemption will not constitute a threat to public safety.


Depicted is an elevational view.

4' TO WIDE, SLOPE GENTLY TOWARD THE POOL. FOR DRAINAGE

12" TO 18' ABOVE WATER SURFACE

PERMANENT WATER LEVEL

44___ 30" BELOW WATER SURFACE




SLOPE TO BE STABLE




4' to B` WIDE, SLOPE GENTLY FOR DRAINAGE






NOTE: NOT DRAWN TO SCALE

NOTE: FOR BASINS WITH PERMANENT
POOL OF WATER ONLY

  1. Illustration of Safety Ledges in a New Stormwater Management Basin

§22-530.8: Requirements for a Site Development Stormwater Plan

A. Submission of Site Development Stormwater Plan

  1. Whenever an applicant seeks municipal approval of a development subject to this ordinance, the applicant shall submit all of the required components of the Checklist for the Site Development Stormwater Plan at §348-8.39.8(C) as part of the submission of the applicant's application for subdivision or site plan approval.

  1. The applicant shall demonstrate that the project meets the standards set forth in this ordinance.

  2. The applicant shall submit 15 copies of the materials listed in the checklist for site development stormwater plans in accordance with §22-530.8(C) of this ordinance.

B. Site Development Stormwater Plan Approval

The applicant's Site Development project shall be reviewed as a part of the subdivision or site plan review process by the municipal board or official from which municipal approval is sought. That municipal board or official shall consult the engineer retained by the Planning and/or Zoning Board (as appropriate) to determine if all of the checklist requirements have been satisfied and to determine if the project meets the standards set forth in this ordinance.

C. Checklist Requirements

The following information shall be required:

  1. Topographic Base Map

The reviewing engineer may require upstream tributary drainage system information as necessary. It is recommended that the topographic base map of the site be submitted which extends a minimum of 200 feet beyond the limits of the proposed development, at a scale of 1"=200' or greater, showing 2-foot contour intervals. The map as appropriate may indicate the following: existing surface water drainage, shorelines, steep slopes, soils, erodible soils, perennial or intermittent streams, waterways that drain into or upstream of the Category One waters, wetlands and flood plains along with their appropriate buffer strips, marshlands and other wetlands, pervious or vegetative surfaces, existing man-made structures, roads, bearing and distances of property lines, and significant natural and manmade features not otherwise shown.

  1. Environmental Site Analysis

A written and graphic description of the natural and man-made features of the site and its environs. This description should include a discussion of soil conditions, slopes, wetlands, waterways and vegetation on the site. Particular attention should be given to unique, unusual, or environmentally sensitive features and to those that provide particular opportunities or constraints for development.

3. Project Description and Site Plan(s)

A map (or maps) at the scale of the topographical base map indicating the location of areas of impervious surface including, but not limited to existing and proposed buildings, roads, parking areas, utilities, structural facilities for stormwater management and sediment control, and other permanent structures. The map(s) shall also clearly show areas where alterations occur in the natural terrain and cover, including lawns and other landscaping, and seasonal high ground water elevations. A written description of the site plan and justification of proposed changes in natural conditions shall also be provided.

4. Land Use Planning and Source Control Plan

This plan shall provide a demonstration of how the goals and standards of §22-530.2 through sections §22-530.5 are being met. The focus of this plan shall be to describe how the site is being developed to meet the objective of controlling groundwater recharge, stormwater quality and stormwater quantity problems at the source by land management and source controls whenever possible.

5. Stormwater Management Facilities Map

The following information, illustrated on a map of the same scale as the topographic base map, shall be included:

  1. Total area to be paved or built upon, proposed surface contours, land area to be occupied by the stormwater management facilities and the type of vegetation thereon, and details of the proposed plan to control and dispose of stormwater.

  1. Details of all stormwater management facility designs, during and after construction, including discharge provisions, discharge capacity for each outlet at different levels of detention and emergency spillway provisions with maximum discharge capacity of each spillway.

6. Calculations

  1. Comprehensive hydrologic and hydraulic design calculations for the pre-development and post-development conditions for the design storms specified in §22-530.3.

  2. When the proposed stormwater management control measures (e.g., infiltration basins) depends on the hydrologic properties of soils, then a soils report shall be submitted. The soils report shall be based on onsite boring logs or soil pit profiles. The number and location of required soil borings or soil pits shall be determined based on what is needed to determine the suitability and distribution of soils present at the location of the control measure.

7. Maintenance and Repair Plan

The design and planning of the stormwater management facility shall meet the maintenance requirements of §22-530.9.

  1. Waiver from Submission Requirements

The municipal official or board reviewing an application under this ordinance may, in consultation with the municipal engineer, waive submission of any of the requirements in §22-530.8(C)(1) through (C)(6) of this ordinance when it can be demonstrated that the information requested is impossible to obtain or it would create a hardship on the applicant to obtain and its absence will not materially affect the review process.

  1. Site Plan Checklist

Major development applications shall require the Applicant shall complete and submit a copy of the Site Conditions Checklist, which can be found immediately following this Section.

S e Rd

In addition to the prescribed information in §22-530.7: Requirements for a Site Development

Stormwater Plan, Part C- Checklist Requirements, the following elements should be considered

and presented as appropriate and in combinations sufficient to adequately indicate the existing

site conditions and that of the surrounding environs:

Yes

No

Not










Applicable













Hydrology










Perennial or intermittent streams as shown on the USGS 7.5










Minute Quadrangle Maps and as indicated in the Soil Survey

of Monmouth County, New Jersey










Special water resource protection areas along all waters

designated Category One at N.J.A.C.










7:9B and perennial/intermittent streams that drain

into/upstream of the Category One waters as

shown on the USGS Quad Maps Soil Survey










Wetlands, NJDEP Linear Non-Tidal Wetlands, Marshlands

and NJDEP Letter of Interpretation findings FEMA Q3 Flood










Data 100 Year-Floodplains and Floodways










Boundaries and Buffers










Appropriate buffers to streams, rivers, wetlands, marshlands,

ponds, lakes and other water bodies as specified in pertinent










"ordinances, rules, regulations, statutes or other provisions of

law imposed by local, County, State or Federal agencies"










Existing and proposed bearing and distances of property lines










Existing and proposed conservation, maintenance,

construction, sight, utility, drainage and right-of way

easements and dedications

In addition

Stormwater

and presented

site conditions

Yes

to the

Plan,

No

as

prescribed information

Part C- Checklist

appropriate and

and that of the surroundin

in §22-530.7: Requirements for a Site Development

Requirements, the following elements should be considered

in combinations sufficient to adequately indicate the existing

environs:

Pervious and vegetated surfaces, i.e. woodlands, grasslands

and other significant natural features










Native and invasive stands of vegetation










Vegetated habitat for Threatened and Endangered Species










Gli= ands










Steep slopes (10% or greater)










Colloidal soils










Highly erodible soils, with an erodibility factor (K) of .40 or

greater










Seasonal high water table










Soils subject to d amic com action and compacted soil










.










Shrink swell potential










Deeply fractured bedrock

Hardpans andElciasi h pans



















Existing Man Made Structures and Activities










Existing buildings and significant permanent manmade

features










Roads by classification, parking areas and other impervious

surfaces










Bridges and culverts










Utilities, sub-surface and above ground mining / quarry

operations and blasting areas










Acid or other hazardous runoff










Areas of fill and buried debris










Wellheads and associated ground water withdrawals










Pipes, discharges and BMP's of existing stormwater utilities










Groundwater mounding










Septic systems and wells of adjacent lots










Leaking sanitary lines










Previous land use (agricultural, industrial, commercial)



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