(Subsection 22-9.5)
*For contiguous buildings (attached dwelling units of two (2) or more two-family units and/or multi-family units), a minimum of two thousand five hundred (2,500) GPM may be used. (Ord. #1045, §9.5)
a. Sanitary Sewer System.
1. All installations shall be properly connected with Keansburg Municipal Utilities Authority sanitary sewer system prior to the issuance of a certificate of occupancy.
2. Subdivisions shall be connected to the existing public sanitary sewer system.
b. System Planning, Design and Placement.
1. The planning, design, construction, installation, modification, and operation of any treatment works shall be in accordance with the applicable NJDEP regulations implementing the New Jersey Water Pollution Control Act (N.J.S.A. 58:10a-1 et seq.) and the New Jersey Water Quality Planning Act (N.J.S.A. 58:11A-1 et seq.)
2. All sanitary sewers, including outfalls, shall be designed to carry at least twice the estimated average design flow when flowing half full. In the case of large interceptor sewer systems, consideration may be given to modified designs.
3. Average daily residential sewer flow shall be calculated as shown in Exhibit 7.
4. System design and placement shall comply with the specifications of the Keansburg Municipal Utilities Authority and the Bayshore Regional Sewerage Authority, as applicable. (Ord. #1045, §9.6)
(Subsection 22-9.6)
a. Based on 100 gallons per day (gpd) per person for single-family detached units and 75 gpd for other housing types (rounded).
b. Based on 65 gpd per person (rounded). Note: These figures do not include allowance for infiltration/inflow. Determination of infiltration/inflow should be made and added to the sewer flow figures shown in this exhibit.
c. Based on four times daily sewer flow (rounded).
a. Purpose.
1. It is hereby determined that the waterways within the Borough of Keansburg are at times subjected to flooding; that such flooding is a danger to the lives and property of the public; that such flooding is also a danger to the natural resources of the Borough of Keansburg, the County and the State; that development tends to accentuate flooding by increasing storm water runoff, due to alteration of the hydrologic response of the watershed in changing from the undeveloped to the developed condition; that such increased flooding produced by the development of real property contributes increased quantities of waterborne pollutants, and tends to increase channel erosion; that such increased flooding, increased erosion, and increased pollution constitutes deterioration of the water resources of the Borough of Keansburg, the County and the State; and that such increased flooding, increased erosion and increased pollution can be controlled to some extent by the regulation of storm water runoff from such development. It is therefore determined that it is in the public interest to regulate the development of real property and to establish standards to regulate the additional discharge of storm water runoff from such developments as provided in this Chapter.
2. The storm water management plans submitted shall demonstrate careful consideration of the general and specific concerns, values and standards of the municipal master plan and applicable County, regional and State storm drainage control program, any County mosquito commission control standards, and shall be based on environ-mentally sound site planning, engineering and architectural techniques.
3. Development shall use the best available technology to minimize off-site storm water runoff, increase on-site infiltration, simulate natural drainage systems, and minimize off-site discharge of pollutants to ground and surface water and encourage natural filtration functions. Best available technology may include measures such as retention basins, recharge trenches, porous paving and piping, contour terraces and swales.
b. System Strategy and Design. Storm water management system strategy and design shall comply with the specifications set forth in the construction specifications.
c. Detention - When Required. Detention will be provided for all major subdivisions and all major site plans resulting in more than ten thousand (10,000) square feet of impervious surface. In such developments, the after development peak rate of flow from the site will not exceed the corresponding flow which would have been created by similar storms prior to development. (Ord. #1045, §9.7)
a. Curbs.
1. The standard curb section used shall be twenty (20') feet in length. All concrete used for curbs shall be prepared in accordance with the requirements by class concrete of the New Jersey Department of Transportation, Standard Specifications for Road and Bridge Construction (latest edition). The twenty-eight (28) day compressive strength of the concrete used shall be not less than the following:
2. Curbs and/or combination curbs and gutters shall be constructed of Class B concrete, air-entrained (5,000 p.s.i.)
3. Where drainage inlets are constructed, but curbs are not required, curbing must be provided at least ten (10') feet on each side of the inlet, set back one (1') foot from the extension of the pavement edge.
4. Open joints shall be provided at intervals of ten (10') feet. One-half (1/2") inch bituminous expansion joints shall be provided every twenty (20') feet.
b. Sidewalks and Bikeways.
1. Sidewalks and Graded Areas.
(a) Sidewalks shall be four (4") inches thick except at points of vehicular crossing where they shall be at least six (6") inches thick. At vehicular crossings, sidewalks shall be reinforced with welded wire fabric mesh or an equivalent.
(b) Concrete sidewalks shall be Class C concrete, having a twenty-eight (28) day compressive strength of four thousand five hundred (4,500) p.s.i. Other paving materials may be permitted depending on the design of the development.
(c) Graded areas shall be planted with grass or treated with other suitable ground cover and their width shall correspond to that of sidewalks.
2. Bikeways.
(a) Bicycle Paths. Dimensions and construction specifications of bicycle paths shall be determined by the number and type of users and the location and purpose of the bicycle path. A minimum eight (8') foot paved width should be provided for two-way bicycle traffic and a five (5') foot width for one-way traffic.
(1) Choice of surface materials, including bituminous mixes, concrete, gravel, soil cement, stabilized earth and wood planking, shall depend on use and users of the path.
(2) Gradients of bike paths should generally not exceed a grade of five (5%) percent, except for short distances.
(b) Bicycle Lanes. Lanes shall be four (4') feet wide, or wide enough to allow safe passage of bicycles and motorists.
(c) Bicycle-safe drainage grates shall be used in the construction of all residential streets.
1. Street Grade.
(a) Minimum street grade permitted for all streets shall be 0.5 percent; but streets constructed at this grade shall be closely monitored and strict attention paid to construction techniques to avoid ponding. Where topographical conditions permit, a minimum grade in excess of 0.75 percent shall be used.
(b) Maximum street grade shall be eight (8%) percent.
2. Intersections.
(a) Minimum intersection angle. Street inter-sections shall be as nearly at right angles as possible and in no case shall be less than seventy-five (75) degrees.
(b) Minimum centerline offset of adjacent intersections. New intersections along one side of an existing street shall, if possible, coincide with any existing intersections on the opposite side of each street. Use of "T" intersections in subdivisions shall be encouraged. To avoid corner-cutting when in-adequate offsets exist between adjacent intersections, offsets shall be at least between one hundred and seventy-five (175') to two hundred (200') feet between centerlines.
(c) Minimum curb radius. Intersections shall be rounded at the curbline, with the street having the highest radius requirement as shown in Exhibit 8 determining the minimum standard for all curblines.
(d) Grade. Intersections shall be designed with a flat grade wherever practical. Maximum grade within intersections shall be five (5%) percent except for collectors which shall be three (3%) percent.
(e) Minimum centerline radius; minimum tangent length between reverse curves; and curb radii. Requirements shall be as shown in Exhibit 8.
(f) Sight triangles. Sight triangle easements shall be required and shall include the area on each street corner that is bounded by the line which connects the sight or "connecting" points located on each of the right-of-way lines of the intersecting street. The planting of trees or other plantings or the location of structures exceeding thirty (30") inches in height that would obstruct the clear sight across the area of the easements shall be prohibited; and a public right-of-entry shall be reserved for the purpose of removing any object, material or otherwise, that obstructs the clear sight.
The distances shown in Exhibit 9 between the connecting points and the intersection of the right-of-way lines shall be required.
3. Pavement.
(a) Pavement design for local and collector streets and parking areas shall adhere to the following specifications for their full paved area as shown on Exhibit 10.
4. Lighting. Lighting shall be designed in accordance with a plan designed by the utility company; or the standards recommended in the IES Lighting Handbook, shown in Exhibit 11, shall be used as a guideline.
d. Water Supply: System Design and Placement.
1. System design and placement shall comply with all applicable NJDEP, AWWA, and Keansburg Municipal Utilities Authority requirements with the strictest standards governing.
2. Fire Hydrants.
(a) Size type, and installation of hydrants shall be in accordance with local practice, or shall conform to the American Water Works Association standard for dry barrel hydrants (AWWA C-502). Hydrants shall have at least three (3) outlets; one outlet shall be a pumper outlet and other outlets shall be at least two and one-half (2 1/2") inch nominal size. Street main connections should be not less than six (6") inches in diameter. Hose threads on outlets shall conform to National Standard dimensions. A valve shall be provided on connections between hydrants and street mains. All pipe, fit-tings, and appurtenances supplying fire hydrants shall be AWWA- or ASTM-approved.
(b) All fire hydrants shall conform to the colorcode system as shown in Exhibit 12.
e. Sanitary Sewers: System Design and Placement. Design and placement of sanitary sewer systems shall reflect New Jersey State regulations and guidelines which implement the New Jersey Water Pollution Control Act (N.J.S.A. 58:10A-1 et seq.) and the New Jersey Water Quality Planning Act (N.J.S.A. 58:11A-1 et seq.) and the requirements of the Keansburg Municipal Utilities Authority.
f. Storm Water Management: System Demand, Strategy, and Design.
1. Storm Water Management: System Demand.
(a) Watershed storm water management re-quires the determination of two runoff parameters: runoff peak rates of discharge and runoff volume. Both parameters shall be used in the comparison of predevelopment and post-development conditions.
(b) Peak rate of discharge calculations shall be used to determine the configurations and sizes of pipes, channels, and other routing or flow control structures. Runoff volume calculations shall be used to determine the necessity for, and sizing of, detention and retention facilities.
(c) Runoff peak rate of discharge calculation. The peak rate of runoff for areas of up to one-half (1/2) of a square mile shall be calculated by the Rational Method or derivatives. The equation for the Rational Method is:
Qp = CIA
Where
Qp = the peak runoff rate in cubic feet per second (CFS)
C.= the runoff coefficient
I.= the average rainfall intensity in inches per hour (in./hr.), occurring at the time of concentration tc (minutes)
tc = the time of concentration in minutes (min.)
A.= the size of the drainage area
(1) Typical C values for storms of 5 to 10 years between periods are provided in Exhibit 13. Runoff coefficients in the following sources may also be used:
U.S. Department of Commerce, Bureau of Public Roads, May 1965, Design of Roadside Channels - Hydraulic De-sign Series No. 4 as supplemented or amended; and Department of Transportation, Federal Aviation Administration, July 1970, AC150/5320-5B, Airport Drainage, as supplemented or amended.
(2) The time of concentration (tc) shall be estimated from Exhibit 14. The analysis shall also consider the procedure outlined in Sections 3.12(c) for Technical Release (TR) No. 55, Urban Hydrology for Small Water-sheds, U.S. Department of Agriculture, Soil Conservation Series, as supplemented and amended (S.C.S. method).
(3) Rainfall intensity as a function of duration and storm recurrence frequency shall be based upon geographically appropriate data as depicted in the plates in technical paper No. 25, Rainfall Intensity Duration-Frequency Curves, U.S. Department of Commerce, Weather Bureau, as supplemented and amended. Rainfall intensity values may also be estimated from Exhibit 15. Intensity curves may be based on local rainfall frequency data, where available. In all instances, a minimum time of concentration of five (5) minutes should be used. For storm sewer design, use the following frequencies:
(i) 10 year up to 21 inches
25.year over 21 inches
50.year over 48 inches
(ii) 50 year from low points (sags)
(iii) 50 year for culverts
(4) The size of the drainage area shall include on-site and off-site lands contributing to the design point.
(5) Computer software adaptations of the Rational Method calculations are acceptable provided that their data and graphic printout allow review and evaluation.
(6) The peak rate of runoff for areas greater than one-half (1/2) square mile shall be calculated by the hydrograph analysis method as outlined in TR No. 55 (S.C.S. method), as supplemented and amended.
(d) Runoff volume calculation.
(1) Runoff volume shall be calculated by the hydrograph analysis method as outlined in TR No. 55 (S.C.S. method). This method shall be used for water-sheds with drainage areas of less than five (5) square miles. For drainage areas of less than twenty (20) acres, the Universal Rational Method hydro-graph approximation may be used as an alternative.
(2) Runoff volume for drainage areas of greater than five (5) square miles shall be calculated by Special Report No. 38, Magnitude and Frequency of Floods in New Jersey with Effects of Urbanization, State of New Jersey, Department of Environmental Protection, Division of Water Resources (Stankowski Method).
(3) Computer software adoptions of these runoff value calculations are acceptable provided that their data and graphic printout allow review and evaluation.
2. Storm Water Management: System Strategy.
(a) A system emphasizing a natural as opposed to an engineered drainage strategy shall be encouraged.
(b) The applicability of a natural approach depends on such factors as site storage capacity, open channel hydraulic capacity, and maintenance needs and resources.
(c) Hydraulic capacity for open channel or closed conduit flow shall be determined by the Manning Equation, or charts/nomographs based on the Manning Equation. The hydraulic capacity is termed Q and is ex-pressed as discharge in cubic feet per second. The Manning Equation is as follows:
Q.= (1.486/n) AR2/3 S1/2 where
n = Manning's roughness coefficient
A.= Cross-sectional area of flow in square feet
R.= Hydraulic radius in feet (R = A/P, where P is equal to the Wetted Perimeter)
S.= Slope of conduit in feet per foot
The Manning roughness coefficient to be utilized are shown in Exhibit 16.
(d) Velocities in open channels at design flow shall not be less than five-tenths (.5') foot per second and not greater than that velocity which will begin to cause erosion or scouring of the channel. Permissible velocities for swales, open channels and ditches are shown in Exhibit 17.
(e) Velocities in closed conduits at design flow shall be at least two (2') feet per second but not more than the velocity which will cause erosion damage to the conduit.
3. Storm Water Management: System Design-Pipe Capacity, Materials, and Placement.
(a) Pipe size shall be dictated by design runoff and hydraulic capacity.
(b) Hydraulic capacity shall be determined by the Manning Equation, except where appropriate, capacity shall be based on tailwater analysis and one-year high tide.
(c) In general, no pipe size in the storm drain-age system shall be less than fifteen (15") inch diameter. A twelve (12") inch diameter pipe will be permitted as a crossdrain to a single inlet.
(d) All discharge pipes shall terminate with a precast concrete or corrugated metal end section or a cast-in-place concrete headwall with or without wingwalls as conditions required.
(e) Materials used in the construction of storm sewers shall be constructed of reinforced concrete, ductile iron, corrugated aluminum, or corrugated steel. The least expensive materials shall be permitted unless site and other conditions dictate otherwise. Specifications referred to, such as ASA, ASTM, AWWA, etc., should be the latest revision.
(1) Reinforced concrete pipe:
(i) Circular reinforced concrete pipe and fittings shall meet the requirements of ASTM C-76.
(ii) Elliptical reinforced concrete pipe shall meet the requirements of ASTM C-507.
(iii) Joint design and joint material for circular pipe shall conform to ASTM C-443.
(iv) Joints for elliptical pipe shall be bell and spigot or tongue and groove sealed with butyl, rubber tape, or external sealing bands conforming to ASTM C-877.
(v) All pipe shall be Class II unless a stronger pipe (i.e., higher class) is indicated to be necessary.
(vi) The minimum depth of cover over the concrete pipe shall be as designated by the American Concrete Pipe Association, as follows:
(2) Ductile iron pipe shall be centrifugally cast in metal or sand-lined molds to ANSI A21.51-1976 (AWWA C151-76). The joints shall conform to AWWA C111. Pipe shall be furnished with flanges where connections to flange fittings are required. Pipe should be Class 50 (minimum). The outside of the pipe should be coated with a uniform thickness of hot applied coal tar coating and the inside lined cement in accordance with AWWA C104. Ductile iron pipe shall be installed with Class C, Ordinary Bedding.
(3) Corrugated aluminum pipe. Within the public right-of-way and where severe topographic conditions or the de-sire to minimize the destruction of trees and vegetation exists, corrugated aluminum pipe, pipe arch or helical corrugated pipe may be used. The material used shall comply with the Standard Specifications for Corrugated Aluminum Alloy Culvert and Under Drains AASHTO designation M196 or the Standard Specification for Aluminum Alloy Helical Pipe AASHTO designation M-211. The minimum thickness of the aluminum pipe to be used shall be: less than twenty-four (24") inch diameter or equivalent, seventy-five thousanths (.075") inch (fourteen gauge); twenty-four (24") inch diameter and less than forty-eight (48") inch diameter or equivalent, one hundred and five thousandths (.105") inch (twelve gauge); forty-eight (48") inch but less than seventy-two (72") inch diameter or equivalent, one hundred thirty-five thousandths (.135") inch (ten-gauge); and seventy-two (72") inch diameter or equivalent and larger, one hundred sixty-four thousandths (.164") inch (eight-gauge).
(4) Corrugated steel pipe may be used in place of corrugated aluminum and shall meet the requirements of AASHTO Specification M-36. Coup-ling bands and special sections shall also conform to AASHTO M-36. All corrugated steel pipe shall be bituminous coated in accordance with AASHTO M-190, Type A minimum.
(a) Pipe bedding shall be provided as specified in Design and Construction of Sanitary and Storm Sewers, ASCE Manuals and Re-ports on Engineering Practice No. 37, prepared by A Joint Committee of the Society of Civil Engineers and the Water Pollution Control Federation, New York, 1969.
(b) Maintenance easements shall be provided around storm water facilities where such facilities are located outside of the public right-of-way. The size of the easement shall be dictated by working needs.
4. Storm Water Management: System Design-Inlets, Catch Basins, and Manholes.
(a) Inlets, catch basins and manholes shall be designed in accordance with State Highway Department Standard Plans and Specification. Frame and grates shall be Campbell Foundry Company Pattern No. 2617 Bicycle Grates with stream-flowing grating, or equal.
(b) Inlet spacing shall be designed to limit gutter flow width to six (6') feet but shall not be more than four hundred (400') feet.
(c) Manhole spacing shall be increased with pipe size.
(d) Manholes shall be precast concrete, brick or concrete block coated with two (2) coats of portland cement mortar.
(e) If precast manhole barrels and cones are used, they shall conform to ASTM Specification C-473 with round rubber gaskets joints, conforming to ASTM Specification C-923. Maximum absorption shall be 8 percent in accordance with ASTM Specification C-478, method A.
(f) If precast manholes are utilized, the top riser section shall terminate less than one (1') foot below the finished grade and the manhole cover shall be flush with the finished grade.
(g) Manhole frames and covers shall be of cast iron conforming to ASTM Specification A-48 Class 30 and be suitable for H-20 loading capacity. All manhole covers in rights-of-way or in remote areas shall be provided with a locking device. The letters "Year 19 " and the words "Storm Sewer" shall be cast integrally in the cover.
5. Storm Water Management: System Design-Detention Facilities.
(a) Development shall use the best available technology to accommodate storm water management by natural drainage strategies as indicated in this section.
(b) Nonstructural management practices, such as open space acquisition, stream encroachment and flood hazard controls shall be coordinated with detention requirements. Changes in land use can often reduce the scope and cost of detention provisions required by means of appropriate change in runoff coefficients.
(c) Detention and all other storm water management facilities shall conform to the standards under the New Jersey Storm Management Act, N.J.S.A. 40:55D-1 et seq.
(d) Where detention facilities are deemed necessary, they shall accommodate site runoff generated from two (2) year, ten (10) year, and one hundred (100) year storms considered individually, unless the detention basin is classified as a dam, in which case the facility must also comply with the Dam Safety Standards, N.J.A.C. 7:20. These design storms shall be defined as either a twenty-four (24) hour storm using the rainfall distribution recommended by the U.S. Soil Conservation Service when using Soil Conservation Service procedures (such as U.S. Soil Conservation Service, "Urban Hydrology for Small Watersheds", Technical Release No. 55) or as the estimated maximum rainfall for the estimated time of concentration of runoff at the site when using a design method such as the Rational Method. Runoff greater than that occurring from the one hundred (100) year, twenty-four (24) hour storm will be passed over an emergency spillway. Detention will be pro-vided such that after development the peak rate of flow from the site will not exceed the corresponding flow which would have been created by similar storms prior to development. For purposes of computing runoff, 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.
(e) In calculating the site runoff to be accommodated by a detention facility, the method to be used is a tabular hydrograph method as presented in TR No. 55 (S.C.S. method) as supplemented and amended.
(f) Detention facilities shall be located as far horizontally from surface water and as far vertically from groundwater as is practicable.
(g) Detention facilities shall not intercept the post-development groundwater table, where practicable.
(h) The following list of general structural criteria shall be used to design storm water detention basins. Due to the uniqueness of each storm water detention basin and the variability of soil and other site conditions, these criteria may be modified or appended at the discretion of the Municipal Engineer if reasons for the variances are indicated in writing.
6. Detention Components: Principal Outlets (Quantity Control).
(a) To minimize the chance of clogging and to facilitate cleaning, outlet pipes shall be at least six (6") inches in diameter. Similarly, riser pipes, if utilized, shall be at least eight (8") inches in diameter. All pipe joints are to be watertight, reinforced concrete pipe. In addition, trash racks and/or anti-vortex devices shall be required where necessary.
(b) Eight (8") inch thick anti-seep collars are to be installed along outlet pipes. Reinforcement steel shall be No. 5 bars at twelve (12") inches both ways with two (2") inches of cover on both faces (minimum).
(c) Where necessary, a concrete cradle shall be provided for outlet pipes.
(d) All principal outlet structures shall be concrete block or reinforced concrete. All construction joints are to be watertight.
(e) Suitable lining shall be placed upstream and down-stream of principal outlets as necessary to prevent scour and erosion. Such lining shall conform to the criteria contained in Hydraulic Engineering Circular No. 15-Design of Stable Channels with Flexible Linings published by the Federal Highway Administration of the U.S. Department of Transportation or Standards for Soil Erosion and Sediment Control in New Jersey published by the N.J. State Soil Conservation Committee.
7. Detention Components: Principal Outlets (Quality Control).
(a) Based upon the requirement limiting the size of the outlet to a minimum of six (6") inches in diameter, water quality control shall be maintained by providing an amount of storage equal to the total amount of runoff which will be produced by the one-year frequency SCS Type III twenty-four (24) hour storm, or a 1.25 inch, two (2) hour rain-fall at the bottom of the proposed detention basin along with a minimum three (3") inch diameter outlet.
(b) The invert(s) of the principal outlet(s) used to control the larger storms for flood control purposes would then be located at the resultant water surface elevation required to produce this storage volume. Therefore, the principal outlets would only be utilized for storms in excess of 1.25 inch, two (2) hour event which, in turn, would be completely controlled by the lower, three (3") inch outlet. If the above requirements would result in a pipe smaller than three (3") inches in diameter, the period of retention shall be waived so that three (3") inches will be the minimum pipe size used. It should be remembered that, in all cases, the basin should be considered initially empty (i.e., the storage provided for the quality requirements and the discharge capacity of its outlet should be utilized during the routing of the larger flood control storms).
8. Detention Components: Emergency Spillways.
(a) Vegetated emergency spillways shall have side slopes not exceeding three (3) horizontal to one (1) vertical.
(b) Emergency spillways not excavated from noncompacted soil, shall be suitably lined and shall comply with criteria contained in Hydraulic Circular No. 15 or Standards for Soil Erosion and Sediment Control.
(c) Maximum velocities in emergency spill-ways shall be checked based on the velocity of the peak flow in the spillway resulting from the routed Emergency Spillway Hydro-graph. Where maximum velocities exceed those contained in Exhibit 17, suitable lining shall be provided.
9. Detention Components: Dams and Embankments.
(a) The minimum top widths of all dams and embankments are listed below. These values have been adopted from the Standards for Soil Erosion and Sediment Control in New Jersey published by the New Jersey State Soil Conservation Committee.
MINIMUM TOP WIDTHS
(b) The design top elevation of all dams and embankments after all settlement has taken place, shall be equal to or greater than the maximum water surface elevation in the basin resulting from the routed Freeboard Hydrograph. Therefore, the design height of the dam or embankment, defined as the vertical distance from the top down to the bottom of the deepest cut, shall be increased by the amount needed to insure that the de-sign top elevation will be maintained following all settlement. This increase shall not be less than five (5%) percent. Where necessary, the Engineer shall require consolidation tests of the undisturbed foundation soil to more accurately determine the necessary increase.
(c) Maximum side slopes for all dams and embankments are three (3) horizontal to one (1) vertical.
(d) All earth fill shall be free from brush, roots, and other organic material subject to decomposition.
(e) Cutoff trenches are to be excavated along the dam or embankment centerline to impervious subsoil or bedrock.
(f) Safety ledges shall be constructed on the side slopes of all detention basins having a permanent pool of water. The ledges shall be four (4') to six (6') feet in width and located approximately two and one-half (2 1/2') to three (3') feet below and one (1) to one and one-half (1-1/2') feet above the permanent water surface.
(g) The fill material in all earth dams and embankments shall be compacted to at least ninety-five (95%) percent of the maximum density obtained from compaction tests performed by the appropriate method in ASTM D698.
10. Detention Facilities in Flood Hazard Areas.
(a) There will be no detention basins in the floodway except for those on-stream.
(b) Whenever practicable, developments and their storm water detention facilities should be beyond the extent of the flood hazard area of a stream. When that is not feasible and detention facilities are proposed to be located partially or wholly within the flood hazard area (as defined by the New Jersey Division of Water Resources), or other areas which are frequently flooded, some storm conditions will make the facility ineffective at providing retention of site runoff. This will happen if the stream is already overflowing its banks and the detention basin, causing the basin to be filled prior to the time it is needed. In such cases, the standards established in these regulations will be modified in order to give only partial credit to detention capabilities located within a flood hazard area. The credit will vary in a ratio in-tended to reflect the probability that storage in a detention basin will be available at the time a storm occurs at the site.
(c) In addition, detention development must be in compliance with all applicable regulations under the Flood Hazard Area Control Act, N.J.S.A. 58:15A-50 et seq.
(d) Detention storage provided below the elevation of the edge of the flood hazard area will be credited as effective storage at a reduced proportion as indicated in the table below:
SIZE OF STORAGE AREA*
*Area contributing floodwaters to the flood hazard area at the site in question. This effective detention storage will be required to provide for drainage of the developed land in accordance with the criteria already established in these regulations. However, the gross storage considered for crediting will not exceed that which would be filled by runoff of a one hundred (100) year storm from the site.
(e) As an alternative to the approach outlined in paragraph f,2. above, if the developer can demonstrate that the detention provided would be effective, during runoff from the one hundred (100) year, twenty-four (24) hour Type II storm, peaking simultaneously at the site and on the flood hazard area, the developer's plan will be accepted as complying with the provisions of paragraph f,2. above.
(f) In making computations under paragraphs f,2. or f,5. above, the volume of net fill added to the flood hazard area portion of the project's site will be subtracted from the capacity of effective detention storage pro-vided. Net fill is defined as the total amount of fill created by the project less the amount of material excavated during the construction of the project, both measured below the excavation of the one hundred (100) year flood but above the elevation of low water in the stream.
(g) Where detention basins are proposed to be located in areas which are frequently flooded but have not been mapped as flood hazard areas, the provisions of either paragraphs f,2. or f,5. will be applied substituting the elevation of a computed one hundred (100) year flood for the elevation of the flood hazard area in paragraph f,2.
11. Detention Facilities: Maintenance and Repair.
(a) Responsibility for operation and maintenance of detention facilities, including periodic removal and disposal of accumulated particulate material and debris, shall remain with the owner or owners of the property with permanent arrangements that it shall pass to any successive owner, unless assumed by a governmental agency. If portions of the land are to be sold, legally binding arrangements shall be made to pass the basic responsibility to successors in title. These arrangements shall designate for each project the property owner, govern-mental agency, or other legally established entity to be permanently responsible for maintenance, hereinafter in this section referred to as the responsible person.
(b) Prior to granting approval to any project subject to review under this Chapter, the applicant shall enter into an agreement with the municipality (or county) to ensure the continued operation and maintenance of the detention facility. This agreement shall be in a form satisfactory to the Municipal Attorney, and may include, but may not necessarily be limited to, personal guarantees, deed restrictions, covenants, and bonds. In cases where property is subdivided and sold separately, a homeowners association or similar permanent entity should be established as the responsible entity, absent an agreement by a governmental agency to assume responsibility.
(c) In the event that the detention facility be-comes a danger to public safety or public health, or if it is in need of maintenance, the municipality shall so notify in writing the responsible person. From that notice, the responsible person shall have fourteen (14) days to effect such maintenance and repair of the facility in a manner that is approved by the Municipal Engineer or his designee. If the responsible person fails or refuses to perform such maintenance and repair, the municipality may immediately proceed to do so and shall bill the cost thereof to the responsible person.
12. Storm Water Management: System Design-Protecting Water Quality.
(a) In addition to addressing water quantity generated by development, a storm water management system shall also enhance the water quality of storm water runoff.
(b) In order to enhance the water quality of storm water runoff, storm water 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 SCS Type III twenty-four (24) hour storm or a 1.25 inch two (2) hour rainfall.
(c) The water quality design storm shall be con-trolled by best management practices. These include but are not limited to the following.
(1) In "dry" detention basins, provisions shall be made to ensure that the runoff from the water quality design storm is retained such that not more than ninety (90%) percent will be evacuated prior to thirty-six (36) hours for all nonresidential projects or eighteen (18) hours for all residential projects. The 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 which would require an outlet size diameter of three (3") inches or less. Therefore, three (3") inch diameter orifices shall be the minimum allowed.
(2) In permanent ponds or "wet" basins, the water quality requirements of this Chapter shall be satisfied where the volume of permanent water is at least three times the volume of runoff produced by the water quality design storm.
(3) Infiltration practices such as dry wells, infiltration basins, infiltration trenches, buffer strips, etc., may be used to satisfy this requirement pro-vided they produce zero runoff from the water quality design storm and allow for complete infiltration within seventy-two (72) hours.
(4) Other suitable best management practices, contained in New Jersey Storm-water Quantity/Quality Management Manual (State of New Jersey, Department of Environmental Protection, February 1981) shall be consulted. (Ord. #1045, §9.8)
