Aberdeen Township City Zoning Code
§ 25-5.23
Surface Water Management.
[Ord. No. 18-1990]
a.
Purpose. It is the purpose of this section to promote the public health, safety and general welfare and to allow the natural recharge of groundwater supplies, protect the ecological health and function of streams and the quality of the waters, alleviate hazards to health and property from surface water run-off, and minimize public and private losses due to surface water run-off damage. Neither property owners whose land is at a lower elevation nor neighboring property owners nor the public at large should bear the cost incident to surface water run-off damage caused by land disturbance. Rather, these costs should be borne in the first instance by the individual property owner or developer who engages in the disturbance which may result in increased or altered surface water run-off.
b.
Word Usage. Unless specifically defined in Section 25-2, words or phrases used in this section shall be interpreted so as to give them meanings they have in common usage and to give this section its most reasonable application.
c.
General Provisions. The following provisions shall be applicable to all methods of surface water management governed by this section unless specifically exempted or waived in accordance with the provisions of this section:
1.
No application for development shall be deemed complete unless the Township Engineer has certified to the approving authority that the applicant has provided the Engineer with sufficient information for it to determine whether or not the proposed development will conform to Township run-off standards, run-off details and stormwater detention facility design criteria.
2.
Planning Board Approval.
(a)
The surface water management plan or any major amendment thereof shall be approved by the Planning Board in the manner and form and according to the regulations hereinafter set forth.
The Planning Board, in approving said surface water management plan, may impose lawful conditions or requirements designated or specified on or in connection therewith. These conditions and requirements shall be provided and maintained as a condition of the establishment, maintenance and continuance of any use or occupancy of any structure or land.
3.
Maintenance and Safety.
(a)
At the time of approval of the plan, responsibility for continued maintenance of surface water run-off control structures and measures shall be stipulated and recorded in the resolution of approval.
(b)
Where continued maintenance is to be the responsibility of the applicant, a proposed maintenance agreement, a form to be provided by the Township, shall be submitted. The agreement shall specify maintenance responsibility and standards during and after completion of the proposed activity and upon approval, shall be recorded by the applicant in the Office of the Monmouth County Clerk. The applicant shall thereafter file a copy of the recorded agreement with the Township Planning Department. The Township shall retain the right to enter and make repairs and improvements where necessary to ensure that all control measures as well as areas dedicated to surface water retention or groundwater recharge are adequately maintained and preserved. The Township may charge the owner for the costs of these services if such maintenance is his responsibility.
(c)
Where continued maintenance of a detention basin is to be the responsibility of the Township, the following provisions shall apply:
(1)
The applicant shall maintain the basin during the construction phase of the project.
(2)
As a condition of final approval and prior to acceptance of the basin by the Township, the applicant shall enter into an escrow agreement with the Township, which agreement shall include a statement that the escrow contribution is made in consideration of the Township assuming all future maintenance of the basin. The form of agreement shall be provided by the Township. The agreement, upon execution, shall be recorded by the applicant in the Office of the Monmouth County Clerk. The applicant shall thereafter file a copy of the recorded agreement with the Township Planning Department.
(3)
The amount of the escrow contribution shall be based upon area of the detention basin on an acreage basis, which shall include the plan area at the top of the bank plus an additional twenty-five (25) feet at the top of the bank encircling the basin. The amount of the escrow contribution shall be calculated according to the following formula:
Nine thousand ($9,000) dollars per acre of area of basin, plus twenty-five thousand ($25,000) dollars per basin for repairs and major maintenance.
The total of the above shall be multiplied by a factor of one and one-tenth (1.1) to cover the cost of the first year of maintenance.
The minimum contribution, regardless of the size of the basin, shall be thirty-five thousand ($35,000) dollars.
(4)
Upon certification by the Township Engineer that the project is complete and the guarantee bond for the project may be released, acceptance of the basin by the Township shall be specifically stated in the resolution authorizing the bond release. The Township shall retain from the cash portion of the bond a sum equal to the escrow contribution calculated by the Township Engineer in accordance with the formula in paragraph c3(c) above. In the event the case portion of the bond is less than the escrow contribution, the developer shall post the deficit in cash prior to release of the bond. Any interim bond reductions authorized by the Township shall not be constructed to mean that all or any part of the detention basin has been accepted by the Township nor shall any such interim reduction reduce the cash portion of the bond to an amount less than the escrow contribution.
(5)
The escrow contribution does not include maintenance of the lot or open space area in which the detention basin is located.
(d)
In the interest of safety to the public, all detention basin outlet structures, existing or proposed, shall be equipped with a debris rack or grating to prohibit entry by persons or by material which may cause clogging. The owner shall be responsible for insuring that such device is functioning properly at all times and is locked in place to discourage removal by unauthorized persons. Design and placement of the safety debris rack should keep in mind the protection of the public at all times to avoid accidental entry or injury.
4.
As-Built Certification. Prior to the acceptance by the Township of any surface water management facilities, the developer's engineer shall certify that said facilities were constructed in accordance with the approved plan, and submit as-built plans for the Township records.
d.
Surface Water Management Plans.
1.
Applicability.
(a)
Plan required. Approval by the municipal agency of a surface water management plan shall be prerequisite to each of the following:
(1)
Preliminary approval of a major subdivision, including that of a planned residential development.
(2)
Preliminary approval of a site plan, including that of a planned residential development.
(3)
Approval of an application to use the residential cluster option.
(4)
A permit for any land disturbance or any construction.
(b)
Exemptions. A surface water management plan shall not be required where:
(1)
The vegetative cover of the land will not be disturbed.
(2)
The site will be used for agricultural or gardening purposes.
(3)
The land disturbance will take place on sites of one (1) acre or less already occupied by a residential dwelling.
(4)
The application for development is for a single-family dwelling.
(5)
The application is for a minor subdivision.
(c)
Waiver. The municipal agency may waive the requirement of a surface water management plan on sites of three (3) acres or less, upon the recommendation of the Township Engineer, where it is satisfied that the proposed activity will not result in surface water run-off damage.
2.
Information Required. A surface water management plan submitted pursuant to this section shall contain the following information:
(a)
Map. A map at a scale of no smaller than one (1) inch to one hundred (100) feet [one to one thousand two hundred (1:1,200)], showing the following:
(1)
Soils of the site prepared from the Monmouth County soil survey map. Appended to this map shall be text describing the pertinent properties and characteristics of the soils shown on this map.
(2)
Topography and drainage, showing contours at five (5) foot intervals where slopes exceed ten (10%) percent and at two (2) foot intervals where slopes are ten (10%) percent or less. Areas officially designated as floodways and flood fringe areas, according to the rules and regulations for delineation of flood hazard areas, as adopted by the New Jersey Water Policy and Supply Council, shall be shown.
(3)
Major vegetative types.
(4)
Location of all proposed changes to the site whether of a permanent or temporary nature, including but not limited to impervious surfaces, improvements or modifications to watercourses, interception of presently dispersed flow and other factors which may affect surface water run-off.
(5)
Location of all proposed measures for surface water run-off control.
(6)
Area of the watershed which drains through the site and the location of the site within the watershed.
(b)
Narrative description. A narrative description shall be submitted, showing proposed measures for surface water run-off control the sequence of installation of the surface water run-off control measures as related to the progress of the project.
(c)
Maintenance agreement. An appropriate maintenance or escrow agreement shall be submitted in accordance with the provisions of subsection 25-9.2.
(d)
Engineering reports. Detailed engineering reports of the following:
(1)
Computations of the surface water run-off, both rate and volume, from the site in the predevelopment condition and in the postdevelopment condition.
(2)
Soil logs and other investigations as needed for proper review of the surface water management plan.
(3)
Detailed engineering plans and performance capabilities of the surface water collection system and the surface water run-off measure.
(e)
Hydrologist's or engineer's statement. A written statement by a hydrologist or licensed engineer shall be submitted, certifying that the proposed surface water management plan will meet all the standards as set forth in subsection 25-5.23d3 and, where applicable, the design standards set forth in subsection 25-5.23e below.
3.
Standards and Principles. The following standards and principles shall be applicable to all surface water management measures:
(a)
Rate of run-off. The peak rate of run-off for a two (2)-year, ten (10)-year and one hundred (100)-year storm from a site during and after development shall not exceed the predevelopment peak rate of run-off, or exceed the capacity of downstream drainage facilities.
(b)
Minimize increase. The increase in total volume of run-off from a site during and after development, from the predevelopment total volume of run-off shall be minimized.
(c)
Control measures. Run-off control measures shall be used both to reduce run-off and to increase recharge. Natural and artificial recharge areas and systems should be employed wherever practicable to minimize the volume of surface water run-off. Proposed site usage shall also be considered with regard to site run-off contaminant levels. On sites containing prime aquifer recharge areas, as delineated by the appropriate critical areas map, surface water run-off control measures which recharge water to the groundwater shall be required.
(d)
Run-off to remain in watershed. Run-off within a site shall ultimately leave the site in the same watershed in which it originated and shall be released in such a manner as to not substantially increase predevelopment erosion of adjacent properties.
(e)
Stormwater control.
(1)
Stormwater-retarding structures shall control all storms occurring more frequently than once in one hundred (100) years including Type III storms as defined by the Soil Conservation Service.
(2)
All facilities located within the Township designed for eventual evacuation of stormwater diverted to them, shall be designed in such a manner to provide for the gradual release of ninety (90%) percent of the run-off from a rainfall measuring one and one-fourth (1 1/4) inches occurring in two (2) hours or less, which release shall be timed so as to be accomplished as close as is reasonably possible to a point in time thirty-six (36) hours after the start of such rainfall; provided, however, that such evacuation from a facility serving residential projects may be designed to accomplish the ninety (90%) percent evacuation from a similar storm time so as to be accomplished at a point in time as close as is reasonably possible to eighteen (18) hours after the start of the rainfall. The specific provisions regarding the timing of evacuation may be waived if the evacuation is accomplished through piping with a maximum diameter of three (3) inches or if the water to be evacuated has reached the facility via unchanneled sheet flow over fifty (50) or more feet of lawn or vegetation of an equivalent nature, provided that said flow shall not cross over any land, improved or unimproved, which may reasonably be expected to add any contaminants or pollutants to the flow which may adversely affect the central supply and which would not be removed from the flow by its passage over the lawn or vegetative area.
(g)
Inlet systems. The inlet system from the final junction to the retarding structure shall be designed to handle one hundred (100)-year storms.
(h)
Water velocity at pipe outlets. The maximum velocity at pipe outlets shall be seven (7) feet per second. To the greatest possible extent, the plan shall avoid the concentration of flow and shall provide for dissipation of velocities at all concentrated discharge points.
(i)
Setback requirements. The top of the excavation or the toe of the outside slope shall be set back twenty-five (25) feet from adjoining nonresidential property lines and fifty (50) feet from an adjoining property line of a lot on which there is a residential use. The edge of the design high water for detention basins shall be set back one hundred (100) feet from existing or proposed dwelling units.
(j)
Calculation of run-off values. Run-off values shall be calculated by the Soil Conservation Service method, the rational method (Q = CIA) or other methods acceptable to the Township Engineer. Either the Monmouth County Engineering Department standards for the coefficient of run-off, as set forth in the Monmouth County Land Subdivision Resolution, on file in the office of the Township Engineer, or other generally accepted engineering standards, whichever are more stringent, should be used.
(k)
Use of existing control measures. Maximum use should be made of presently existing surface water run-off control measures, including but not limited to berms, terraces, grassed waterways, swamps, swales, ditches, woodlands, floodplains, favorable hydrologic soils or watercourses.
(l)
Run-off control measures. Run-off control measures listed in Urban Hydrology for Small Watersheds, TR 55, United States Department of Agriculture, Soil Conservation Service, on file in the office of the Township Engineer, may be employed.
(m)
Cluster development. The use of cluster development and conservation easements should be considered to reduce the rate or volume of surface water run-off, to reduce the total area of impervious surfaces and to preserve open space and topographic features critical to surface water run-off control.
(n)
Construction of run-off control measures. The plan shall consider construction of specific water run-off control measures prior to beginning other land disturbance activities.
(o)
Completion of run-off control measures. All water-carrying structures and/or detention areas shall be completed and stabilized prior to certification of completion by the Township Engineer and acceptance by the Township.
(p)
Vegetative cover. Reestablishing vegetative cover shall be in accordance with Standards for Soil Erosion and Sediment Control in New Jersey, adopted by the Freehold Soil Conservation District, latest edition.
(q)
Standards for run-off control measures.
(1)
All measures for surface water run-off control measures shall be equal to or exceed the standards for such measures as promulgated by the New Jersey State Soil Conservation Committee and the Freehold Soil Conservation District, which shall be on file in the office of the Township Engineer.
(2)
Where applicable, an applicant shall certify through a licensed engineer that proposed stormwater management facilities have been designed in a manner consistent with dam safety and other design standards in accordance with the then current state of the art for such structures and in accordance with any and all standards which may be required by law or regulation.
4.
Grading Plans.
(a)
A certified grading plan shall be submitted by the developer prior to the issuance of a building permit. The grading plan shall show no less than a two (2%) percent slope for surface run-off, not to exceed two (2) lots; alternatively, lawn outlets must be provided. Grading plans showing slopes exceeding four (4%) percent must be approved for erosion protection by the Township Engineer.
(b)
Prior to the issuance of more than eighty (80%) percent of the Certificates of Occupancy for each block, a certified as-built grading plan shall be submitted by the developer, indicating that the approved grading plan is being complied with. For purposes of this section "block" shall be defined as a lot or lots bounded by streets, highways, rivers and prominent streams as the same shall be depicted on the Official Tax Map of the Township of Aberdeen.
e.
Detention Basins. In addition to all other provisions of this section, where a surface water management plan includes a detention basin, the following provisions shall apply:
1.
Dry Detention Basins. The following design standards shall apply to all dry detention basins:
(a)
Side slopes shall be one (1) vertical to three (3) horizontal.
(c)
An area fifteen (15) feet wide with a maximum slope of two (2%) percent shall be constructed at the top of the bank surrounding the basin.
(d)
To provide accessibility to the bottom, an area with a minimum width of eighteen (18) feet and having a slope no greater than one to four (1:4) shall be constructed.
(e)
If the areas described in paragraphs a1(c) and (d) above require stabilization, they shall be stabilized by paving blocks for Fire Emergency Access Lane.
(f)
All storm sewer discharge outlets into the basin shall be at the grade of the basin's bottom.
(g)
All stabilization of conduit shall be by riprap or concrete.
(h)
The top of the excavation or the toe of the outside shall be set back twenty-five (25) feet from adjoining nonresidential property lines and fifty (50) feet from an adjoining property line of a lot on which there is a residential use. The edge of the design highwater for detention basins shall be set back one hundred (100) feet from existing or proposed dwelling units.
(i)
Vegetative stabilization cover shall be provided throughout the basin and landscaping shall be provided on the perimeter.
(j)
The basin floor shall lie two (2) feet above the seasonal high ground water table.
(k)
Discharge structure. The discharge structure shall be in accordance with the following standards:
(1)
A minimum twelve (12) inch diameter discharge is recommended (except where a three (3) inch diameter orifice is required for water quality measures).
(2)
Trash rack and safety protections shall be provided for all smaller diameter outlets.
(3)
All stored stormwater must discharge from the basin within two (2) days (forty-eight (48) hours).
(4)
No detention basins shall be located in floodways, wetlands or floodplains.
2.
Recharge Basins. Where a recharge basin is to be constructed, the standards for dry detention basins, as set forth above, shall be applicable, together with the following:
(a)
The applicant shall provide detailed soils data for each basin site, to include:
(1)
Soils data to a depth of at least six (6) feet below the proposed basin floor.
(2)
The elevation of the seasonal high ground water table. The seasonal high water table must be at least two (2) feet below the proposed basin floor.
(3)
The soil percolation rate for the soils at the elevation of the proposed basin floor.
(b)
Recharge enhancement by means of stone filled trenches or porous pipe, shall be situated at the lowest elevation of the basin.
(c)
Where practical, the basin floor elevation shall be established at or above waterways or storm sewers in the area.
(d)
Where the basin floor elevation is established at or above waterways or storm sewers in the area, alternate discharge measures for emergency basin drainage, such as "plugged" outlet pipes in place at the basin floor elevation, shall be provided. Manual valves are optional.
3.
Wet Detention Basins (Ponds).
(a)
Where a wet detention basin is to be constructed, the applicant shall provide an environmental study which includes the following:
(1)
Recharge water volume, to include storm run-off, stream flow and ground water elevation.
(2)
Recharge water quality, to include run-off from parking lots, streets and roofs. Sources of pollution shall be identified.
(3)
Basin floor soils, impervious strata is required.
(4)
Aeration requirements (dissolved oxygen). Basins with on-site recharge only may require supplementary aeration.
(5)
Aquatic community development to include water depth minimum five (5) feet, fish stocking species.
(b)
A safety edge five (5) feet wide and eighteen (18) inches below the design high water level shall be constructed around the entire interior perimeter of the basin slope.
4.
Maintenance. Detention basins 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 build-up 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 health problem, unless approved as a multifunction facility to include water such as a pond. Failure to maintain detention basins to the degree that mosquito or other noxious pest habitats develop is a violation of the Mosquito Extermination Act (N.J.S.A. 26.9-1, et seq.) and shall subject the owner to civil sanctions by the Township Health Department. An annual maintenance report addressing the function, condition, safety and aesthetics of the facility shall be prepared by the owner and submitted to the Township Manager by December 1 of each year.
f.
Review and Approval of Plans. Surface water management plans shall be reviewed by the Planning Board, which may receive the advice and assistance of the Township Engineer, the Freehold Soil Conservation District, the Monmouth County Mosquito Control Commission and the Environmental Commission. The Planning Board's consideration of applications shall be guided by, but not limited to, the following factors:
1.
The suitability and effectiveness of the plan.
2.
The existing topography, vegetation, hydrologic factors and soil conditions.
3.
The groundwater supply, groundwater recharge, and discharge areas, wet soils and the depth to the seasonal high water table.
4.
The natural drainage flow and pattern.
5.
Rainfall intensity and duration for two (2)-year, ten (10)-year, twenty-five (25)-year and one hundred (100)-year storms.
6.
Critical and environmentally sensitive areas on the site.
7.
Land uses in both the immediate vicinity of the site and the surrounding drainage region.
8.
Aesthetics and compatibility with the adjoining uses both on and off site.
9.
Other applicable environmental, resource or public health protection ordinances, statutes or regulations.
g.
Application Procedure for Plan Unrelated to a Development Application.
1.
Copies of Plan and Application. At least ten (10) days and no more than twenty (20) days before a regular meeting of the Planning Board, the applicant shall submit twelve (12) copies of a surface water management plan as set forth in subsection 25-5.23d and three (3) completed copies of an application form which shall be obtained from the Secretary of the Planning Board.
2.
Copies to Municipal Officials; Reports. The Secretary of the Planning Board shall forward a copy of the application to the Township Engineer, the Planner and such other officials as the Board shall direct and shall request that each of them file a written report of his findings and recommendations, giving full consideration to the standards and principles set forth in this section and stating whether the application is feasible and sound from an engineering standpoint.
4.
Signatures upon Approval. If the application is approved, said approval shall be noted on the plan, and it shall be signed by the Chairman and the Secretary of the Planning Board.
5.
Time for Approval or Denial. Approval shall be granted or denied within forty-five (45) days after submission of a complete application to the Secretary of the Planning Board or within such further time as may be consented by the applicant. Failure of the Planning Board to act within the period prescribed shall constitute final approval, and a certificate of the Township Clerk as to the failure of the Board to act shall be issued at the request of the applicant.