Township of Mannington, NJ Improvements and Design Standards

All proposed streets in a subdivision of land shall be classified as either a loop street, a cul-de-sac street or a Township collector as defined on Plates 2, 3, and 4.[1] All loop streets and cul-de-sac streets shall be entirely contained within the Township of Mannington and may not extend across a municipal boundary line so as to be partly in another municipality. All proposed streets in a subdivision, including cul-de-sac streets, loop streets and the portion of collector streets within the Township, shall provide access only to lots which meet the area dimension and lot configuration standards for such lots with land entirely within the Township of Mannington.

[Amended 5-4-1989 by Ord. No. 89-7]

Editor's Note: Plates 2, 3 and 4 are included at the end of this chapter.

Loop streets, cul-de-sac streets, and other existing minor streets shall be so designed and integrated into the circulation pattern of the subdivision and the immediate area so as to discourage through traffic.

Township collectors shall be designed to provide for the extension and connection of existing streets except when such a connection will result in a major diversion of traffic from major collectors or arterials through the subdivision.

When a subdivision adjoins land susceptible to being subdivided, suitable provisions shall be made for optimum access of the remaining and/or adjoining tract to existing or proposed streets within the proposed subdivision.

Access shall be designed in all major subdivisions according to the following standards:

All major subdivisions bounded by arterials, major collectors, and minor collectors as defined by the Functional Classification System contained within the approved Township Master Plan shall control access to said streets by having all driveways intersect marginal service streets, parallel streets, or streets intersecting said arterials, major collectors, and county-local roads.

When a subdivision of five or more lots borders on an existing Township street, or county-local road reverse frontage or a marginal service road may be required.

When a proposed street (Township collector) will serve more than 50 lots in a fully developed subdivision, all driveways within that subdivision shall intersect loop streets, cul-de-sac streets or marginal service roads.

All subdivisions which control access to existing Township or county roads by reverse frontage or marginal service roads shall construct an adequate buffer between the development and the existing street. The buffer for reverse frontage shall consist of densely planted nursery grown trees to a depth of 20 feet as indicated on Plate 5. Plate 6 indicates the required landscaped area for marginal service roads.[2]

[2]

Editor's Note: Plates 5 and 6 are included at the end of this chapter.

No subdivision showing reserve strips controlling access to streets or other areas, either developed or undeveloped, shall be approved except where the control and disposal of land comprising such strips has been given to the governing body after recommendation by the approving authority.

(8)

A subdivision that adjoins or includes existing Township streets that do not conform to the right-of-way widths specified in the Township Master Plan in the street cross section requirements of this chapter shall dedicate the additional land needed to conform to the right-of-way standards. If the subdivision is along one side of the road, 1/2 of the required extra width shall be dedicated.

(9)

A cul-de-sac shall provide access to a minimum of six lots and a maximum of 14 lots. No cul-de-sac shall exceed 750 feet in length measured from the intersecting street right-of-way to the end of the turnaround right-of-way. The minimum radius of a cul-de-sac shall be 50 feet in zoning districts with a minimum lot width of 150 feet or more and 60 feet in zoning districts with a lot width requirement of less than 150 feet. The right-of-way radius of the turnaround shall be 60 feet and 70 feet for these respective zoning districts. No cul-de-sac turnaround shall exceed a radius of 70 feet except if an adequate landscaped circle is provided in which two-way traffic is maintained.

(10)

All streets and subdivisions should be so oriented as to permit, within the limits of practicability and feasibility, the buildings constructed thereon to maximize solar gain.

[Added 6-7-1984 by Ord. No. 84-3]

Specific design requirements. The following specific design requirements shall be met in the construction of new streets or the improvements of existing streets:

When connecting street lines deflect from each other at any one point by more than 10° they shall be connected by a curve with a radius conforming to standard engineering practice so that the minimum sight distance shall not be less than 100 feet for cul-de-sacs, 150 feet for loop streets, and 300 feet for collectors and arterials.

A tangent of at least 200 feet shall be introduced between reverse curves on arterial and collector streets.

Longitudinal grades on Township collectors or roads of higher functional classification shall not exceed 4%. The longitudinal grade of any other local street shall not exceed 8%. All changes in grade shall be connected by vertical curves of at least 50 feet for each 2% (or portion thereof) difference in grade to ensure proper sight distance which will conform to good engineering practice.

The longitudinal grade of any street shall not be less than 1/2 of 1%. Grades between 1/2 of 1% and 1% may require monolithic curb and gutter construction to ensure adequate drainage.

Intersections:

Street intersections shall be at a minimum angle determined by the road classification. All intersections shall be at 90 degrees except that cul-de-sac or loop streets which intersect a Township collector or county-local road shall have a minimum angle of 75° and a cul-de-sac which intersects a loop street shall have a minimum angle of 60°.

No more than two streets shall meet or intersect at any one point and the center line of both intersecting streets shall pass through a common point. Any two intersections shall be separated by the following distances:

	Classification	Minimum Distance Between Intersections (feet)
	Arterials county collectors	350
	Township collectors, county-locals	250
	Loop streets, culs-de-sac	200
	Whenever two roads of different functional classification intersect, the minimum separation standards of the more important road shall be followed.

The maximum grades of all intersections shall be 3% except that intersections involving only Township collectors or other local streets shall have a maximum grade of 4%.

The block corners at intersections shall be rounded at the curb line with the street having the highest radius requirement determining the minimum standard for all curb lines.

	Classification	Radius (feet)
	Arterials county collectors	40
	Township collectors, county-locals	30
	Loop streets, culs-de-sac	20

For both major and minor subdivisions, clear sight triangle easements shall be required at all intersections in addition to the right-of-way requirement described above. Within such triangles, no vision-obstructing object shall be permitted which exceeds a height of 30 inches above the elevation of the intersecting streets except for lighting standards. The sight triangle is defined as the area of vision which enables a motorist entering a road to perceive oncoming vehicles and which enables oncoming vehicles to perceive the entering vehicle. This area is bounded by the intersecting street lines and the straight line connecting street sight points, one each located on the two intersecting street center lines. "Sight points" are defined as being the following distances from the intersection:

	Classification	Distance (feet)
	Arterials	400
	County major collectors	300
	County minor collectors	250
	Township collectors, county-locals	200
	Loop streets	150
	Culs-de-sac	110
	These points are to be connected to a point 90 feet from the intersection of the street center lines. Plates 7 through 10[3] illustrate the required sight-triangle easements. The sight easement shall describe two overlapping triangles whenever the intersecting roads are of Township collector or above functional classification. The easement for intersections involving cul-de-sac or loop streets shall only include the sight triangle needed for the motorist entering the intersecting street.

[3]

Editor's Note: Plates 7 through 10 are inclded at the end of this chapter.

Street construction standards. All subdivisions shall be served by paved public streets with an all weather base and pavement with an adequate crown. All new streets and improvements to existing streets shall adhere to the following standards:

The minimum pavement width shall be in accordance with the following standards and as illustrated on Plates 11 through 16:[4]

Type of Street	Lanes No.	Width (feet)	Shoulder Width (feet)	Type	R.O.W. (feet)
County major collector	2	12	6	1	86
County minor collector	2	12	6	2	66
County local	2	11	6	2	50
Township collector	2	11	6	1	50
Loop	2	11	5	1	50
Cul-de-sac	2	11	3	1	50

Shoulder types:

Paved.

[2]

Application, oil and stone and gravel.

In areas proposed for less intense development (minimum lot sizes over one acre), the minimum shoulder shall be compacted gravel with oil.

[4]

Editor's Note: Plates 11 through 16 are included at the end of this chapter.

All new and existing streets shall be constructed or improved to fulfill the above minimum requirements. The subdivider shall be responsible for improving only 1/2 of the street immediately adjacent to the subdivision, except in cases where off-site contributions are required. If off-site contributions are required the subdivider may be responsible for improving more than 1/2 of the street and other nearby streets or intersections.

Deceleration and acceleration lanes shall be constructed outside of the normal cartway as determined necessary by the Township Engineer.

The minimum total asphalt surface thickness for all pavements shall be 3 1/2 inches of FABC-2, Mix No. 5. Two inches to be laid and used as running surface until all settlement is completed, then brought to final grade with an overlay of 1 1/2 inches and such additional material as shall be needed to compensate for settlement. The minimum subbase shall be four inches of soil aggregate Type 5, Class A, or, as an alternate subbase, with Planning/Zoning Board approval, six inches of soil aggregate Type 2, Class B. No bituminous concrete pavement shall be laid until the existing subbase has been prepared and thoroughly compacted with an approved roller.

The minimum requirements of any new street shall be in accordance with the specifications and procedures set forth in the New Jersey State Highway Department Standard Specifications (1961) and all addenda or revisions thereto.

Whenever curbing and guttering are required under this chapter, it shall be constructed in a manner approved by the Township Engineer. If concrete, the curbing and gutters shall meet the following specifications:

The concrete to be used for curbs and gutters shall be Class B concrete as specified in the New Jersey State Highway Specifications for Curbs and Gutters.

Expansion joints shall be provided at intervals of 20 feet.

Concrete curbs shall be eight inches wide at their base and not less than six inches wide above the roadway pavement. The rear top corner of this curb shall have a radius of 1/4 inch and the front top corner shall have a radius of 1 1/2 inches.

Combination curbs and gutters shall be constructed on a base of sand, or other similar pervious material six inches in depth and extending 12 inches beyond the rear face of the curb and 12 inches beyond the face of the curb. The total width of the curb and gutter shall be 30 inches. The dimensions of the particular parts of the combined curb and gutter shall be as follows: (See Plate 4.)[5]

The top of the curb shall be six inches in width.

[2]

The rear of the curb shall be 12 inches in height.

[3]

The width of the curb at the gutter elevation shall be seven inches.

[4]

The height of the curb face at the gutter shall be six inches and the depth of the gutter at the street face shall also be six inches.

[5]

All exposed edges shall be rounded with a radius of 3/4 inch to one inch.

[5]

Editor's Note: Plate 4 is included at the end of this chapter.

Openings for driveway access shall be in such width as shall be determined by the Township Engineer, but in no case more than 15 feet at the edge of the pavement. The curb at such driveway openings shall be depressed to the extent that 1 1/2 inches extend above the finished pavement. The rear top corner of this curb shall have a radius of 1/4 inch and the front top corner shall have a radius of 1 1/2 inches.

All work shall be inspected through the course of construction by the Township Engineer or his/her duly authorized representative who shall be notified 48 hours in advance before any work is started or completed.

§ 70-89 Drainage.

General design considerations:

The drainage system of a proposed subdivision should be adequate to carry off and/or store the stormwater and natural drainage water which originates not only within the subdivision boundaries, but also that which originates from the total natural watershed surrounding the property in question.

The drainage system shall be designed to control the amount and rate of stormwater runoff. A general principle for major subdivision design shall be to not increase the parcel's amount or rate of stormwater runoff by the use of structural and nonstructural measures.

Whenever possible, any major development's drainage system shall be designed for the recharge of groundwater and the retention of stormwater on site.

Provisions shall be made to limit the amount of sedimentation and other pollutants that may enter a natural watercourse as a result of the development.

Where possible, a subdivision's stormwater management design shall preserve stream channels, floodplains, and wetlands in their natural condition to act as buffers against flooding and pollution.

No stormwater runoff or natural drainage water shall be so diverted as to overload existing drainage systems, create flooding, or require the construction of additional drainage facilities in other private or public lands without proper and approved provisions being made for remedying these off-site or off-tract conditions.

For all subdivisions, land subject to periodic or occasional flooding (floodplain areas) shall not be plotted for residential occupancy nor for any other purpose which may endanger life or property or aggravate the flood hazard. Such land within a plat shall be considered for open land use.[1]

Editor's Note: See Ch. 57, Flood Damage Prevention.

Specific design considerations:

For all subdivisions where the average elevation of the lot or the elevation of the building site is below the crown of the existing or proposed road, the lot shall be properly graded to ensure proper drainage away from buildings and to prevent the ponding of stormwaters in front, side, or rear yards. A grading plan must be submitted for such lots to ensure proper drainage prior to subdivision approval.

All streets shall be provided with catch basins and pipes where necessary for proper surface drainage. Dry wells are specifically prohibited as alternatives to catch basins, or as a method of recharge.

The materials used for drainage facilities and appurtenances shall be in conformance with Standard Specifications for Road and Bridge Construction of the New Jersey Department of Transportation, 1961, and all addenda. The technique for calculations and design parameters shall be by the rational method for drainage sheds less than four acres and the Soil Conservation Service method for drainage sheds above four acres. The following recurrence interval parameter shall be adhered to: minor inlets, two years; low points, five years; sump inlets, 10 years; minor stream structure, (50 acres or less), 10 years; major stream structures with no headwaters, 25 years; and major stream structures with maximum headwater, 100 years. Single Type B inlets shall not be designed to catch more than 5 1/2 cubic feet per second, regardless of head, but shall not be spaced greater than 500 feet center to center. Discharge and collection systems shall not be designed for inlet head under any circumstances.

Drainage structures which are located on state or county highway rights-of-way shall be approved by the State or County Highway Engineer's office, and a letter from that office indicating such approval shall be directed to the Township Planning/Zoning Board and shall be received prior to the final plat approval. Drainage structures proposed on a brook or stream with a drainage area of 1/2 square mile (320 acres or greater) shall be approved by the New Jersey Division of Water Policy and Supply, and a letter from the office shall be directed to the Planning/Zoning Board Chair.

All proposed subdivisions or developments abutting a brook or stream whose drainage area, up to and including the subdivision or development, is greater than 50 acres shall be required to secure a stream encroachment permit from the New Jersey Division of Policy and Supply, Bureau of Floodplain Management, prior to the authorization of final approval. Furthermore, a copy of the permit shall be forwarded to the Planning/Zoning Board and shall be attached to the final engineering plans of same.

Road drainage. The use of swales for road drainage purposes may be permitted at the discretion of the Township Planning/Zoning Board, provided that the subdivision is under 20 lots, the minimum lot size is greater than one acre, and that the grade does not exceed 6% nor is less than 1/2 of 1%. In subdivisions with more than 20 lots, swales may only be permitted along roads in which reverse frontage has been provided. Where these conditions are not met or where drainage conditions warrant, curbing and guttering shall be required along all existing and proposed streets. In minor subdivisions, curbing and guttering may be required where drainage or traffic conditions warrant or when the subdivision is in proximity to existing curbed and guttered areas.

Land drainage. All surface drainage shall be piped unless the developer demonstrates that the use of swales is a more appropriate form of conveyance to the satisfaction of the Township Planning/Zoning Board. The use of swales shall not be permitted where the adjacent lot sizes on the same tract are 25,000 square feet or less.

(8)

Swales, where permitted, shall be designed according to the following standards:

Swales shall have a parabolic or trapezoid shape.

Side slopes of a swale along a road shall not be steeper than 4:1 adjacent to the road and 2:1 on the slope away from the road. Side slopes of swales not along a road shall not exceed 3:1.

Trees, brush and stumps, as well as other objectionable material are to be cleared and disposed of so as not to interfere with construction or proper functioning of the waterway.

Separate areas filled are to be compared as needed to prevent unequal settlement that will cause damage in the completed waterway.

Waterways and outlets shall be protected against erosion by vegetative means as soon after construction as practical before diversions or other channels are outletted into them. Seeding, fertilizing, mulching, and sodding shall be in accordance with the applicable standards as determined by the Soil Conservation Service of the State of New Jersey.

(9)

Storm sewer pipe shall be installed in accordance with proper engineering practices and shall be designed according to the following standards:

The pipe shall be concrete or aluminum as required by the Township Engineer. Nonreinforced concrete pipe shall conform to AASHOM-86 for specified diameter and strength class. Reinforced concrete pipe shall conform to AASHOM-170 for specified diameter and strength class. Aluminum alloy pipe shall conform to AASHOM-197 for specified diameter and strength.

All drainage pipes shall have a minimum diameter of 15 inches. The pipe shall be laid in straight alignment, between manholes. All transitions in slope, change of direction or pipe size shall be confined to manholes, catch basins, or other accessible structure.

The size of the pipe, slope and invert elevations shall be submitted on a final drainage plan.

In those areas where the groundwater elevation is such that roadway subbase instability could occur from same, the Planning/Zoning Board Engineer shall reserve the right to require extra strength porous concrete pipe in lieu of either reinforced concrete or corrugated aluminum storm sewer conduit for the purpose of adequately underdraining the surrounding soil and stabilizing the affected subbase.

Slotted drain pipe shall not be permitted except if approved by the Township Engineer.

(10)

Where a subdivision is traversed by a watercourse, surface or subsurface drainageway, channel or stream, or a subdivision proposes the creation of such surface or subsurface drainageways, there shall be provided and dedicated a drainage right-of-way easement to the Township. The width of the drainage easement required shall be determined by the Township Engineer based upon the width needed to accommodate future stormwater run off and to allow sufficient area for maintenance or construction activities. A minimum width of all drainage easements shall be 40 feet or 20 feet from the edge of the watercourse.

(11)

Detention basins shall be designed in accordance with the following criteria:

Inflow Q shall be designed for a twenty-five-year recurrence interval under full development conditions within the subdivisions.

Outflow Q shall be designed based on the capacity of the nearest downstream drainage structure, and it shall not be more than the ten-year recurrence interval under full development conditions within the subdivision.

All detention basins shall have a minimum freeboard of one foot above the design high-water level and shall likewise have an emergency spillway capable of discharging flow from a design storm with a recurrence interval of 100 years. Where the depth of high water in any basin exceeds two feet, then a fence of minimum height of eight feet and made of approved material shall be required.

Detention basins are not permitted where soils have a percolation rate of less than five minutes per inch or more than 60 minutes per inch.

(12)

Retention basins shall be designed in accordance with the following criteria:

Inflow Q shall be designed as required for detention basins.

Outflow Q shall not be considered for any basin whose soil percolation rate is in excess of six minutes per inch.

The bottom elevation of all retention basins shall be a minimum of two feet above the seasonal high-water table. Overflow and freeboard design shall be as previously specified for detention basins. Fencing requirements shall likewise be as previously specified for detention basins.

The preferred side slope of the banks for either detention or retention basins shall be a 5:1 ratio with a minimum acceptable ratio of 3:1 if conditions do not permit.

Retention basins are not permitted where soils have a percolation rate of less than five minutes per inch or more than 60 minutes per inch.

(13)

Collection basis.

The collection basis shall be designed in accordance with the rational method expressed as the equation Q= AIR where:

	Q =	Volume of run off in cubic feet per second
	A =	The contributory drainage area, in acres, both within and outside the boundary of the subdivision.
	I =	Coefficient of runoff applicable to the drainage area. It shall consider the soil character, slope of area and degree of ultimate development as determined by current zoning. In general, the values of the run off coefficient will fall within the following range:

	Classification	Coefficient
	Park lands, golf courses, etc	0.15 to 0.30
	Densities below DU/acre	0.30 to 0.50
	Densities of 2 DU/acre and above	0.50 to 0.70
	Commercial and industrial	0.70 to 0.90

For composite areas of various classifications, the coefficient for the predominate area shall be used for all calculations.

R =

Rainfall intensity. A minimum intensity of 2.75 shall be used.

(14)

Flow design criteria. Velocity of flow shall be determined by Manning's Formula:

	V = 1 486R2/3S1/2 n
	R =	Hydraulic radius of conduit, or area of stream divided by wetter perimeter.
	S =	Slope of hydraulic grade line, or for open channels or ditches, the slope of the water surface.
	n =	the coefficient of friction.
		Acceptable values of "n" are:
		.015 for circular cross section, nonporous concrete pipe.
		.015 for pipes 18 inches or smaller in diameter and concrete lined ditches.
		.025 for clear unlined ditches.
		.03 to .15 for fair to poor natural streams and watercourses.
		Other cross sections of pipe materials shall have commensurate friction factors as may be approved by the Township Engineer.

	Permissible Design Velocities Open Channel Ditches
	Material	Velocity (feet per second)
	Fine sand to loam	2.5 to 3.5
	Clay to hardpan	3.75 to 6.0
	Concrete lined	15
	Pipe	*
	*Minimum design velocity at "flowing full" condition shall be three feet per second. Pipes shall be considered "flowing full" at maximum capacity.

§ 70-90 Lot configuration.

Lot dimensions and area shall not be less than the requirements of Part 3, Zoning, of this chapter.

Insofar as practical, side lot lines shall be at right angles to straight streets and radial to curved streets.

Where additional right-of-way has been required to bring existing rights-of-way up to standard, lots shall begin at the proposed right-of-way line and all setback shall be measured from that line.

For proper development of the land within the Township, lots shall have an average length no greater than 250% of the average width, except where the width exceeds three times the zoning requirement.

Where there is a question as to the suitability of a lot or lots for their intended uses due to factors such as poor drainage conditions or where percolation tests or test borings show the ground conditions to be inadequate for proper on-lot sewage treatment, the Planning/Zoning Board may, after adequate investigation, withhold approval of such lots. If approval is withheld, the Board shall specify the reasons for such denial in the minutes.

§ 70-91 Natural features.

The important natural features of a site shall be preserved in the design of all subdivisions. Natural features which shall be protected include the natural terrain, wetlands, wooded areas, vistas, natural drainageways, and lakes. A developer shall only be permitted to significantly alter or encroach on the existing natural features if the Planning/Zoning Board is convinced that the alteration is the minimum necessary to allow the use of the land for the intended purpose and that there are no alternatives to the subdivision design which would eliminate or mitigate any adverse impact on natural features.

§ 70-92 Trees.

The clearing of woodland shall be strictly controlled. The stripping of trees from a lot and the filling, or the alteration of the water table in wooded areas shall be prohibited except if an extensive replacement tree planting program has been approved by the Township Planning/Zoning Board. All subdivisions and developments shall be designed to have minimal impact on existing woodland. The siting of structures shall be such as to preserve the maximum number of trees over 15 inches in diameter and all trees over 24 inches in diameter.

Shade trees. In all major subdivisions, shade trees shall be provided along the road frontage. Two trees properly planted, staked, and fertilized shall be provided for every 100 feet of road frontage except if an equivalent number of trees are preserved within 50 feet of the right-of-way. All shade trees shall meet the following requirements:

Trees shall be a deciduous variety (oak, hard maple) native to the area and shall be approved by the Planning/Zoning Board.

Trees shall be nursery grown and shall have a minimum caliper of 1 1/2 inches measured three feet above the ground.

Trees shall be planted where required by the Planning/Zoning Board in a planting strip 10 feet from the edge of the shoulder when the road has been designed according to the approved cross sections.

§ 70-93 Topsoil protection.

No topsoil shall be removed from the site or used as spoil. Topsoil moved during the course of construction shall be redistributed within the subdivision so as to provide at least four inches of cover to all areas of the subdivision and shall be stabilized by seeding or planting.

§ 70-94 Pedestrian circulation.

A pedestrian circulation system shall be provided for all major subdivisions over 20 lots and may be required whenever an interior street system is utilized. The system shall include sufficient sidewalks and interior walkways to provide safe pedestrian movement between residential units and to provide access to environmental amenities, recreation areas, and other forms of pedestrian attraction within, adjacent to, or in proximity (1/2 mile) of the site. The circulation system shall connect with any existing or proposed adjacent developments and may or may not be related to the street system. The Township Planning/Zoning Board shall review and approve the proposed circulation system.

In all major subdivisions, sidewalks shall be required along both sides of roads classified as Township collectors or county-local roads.

Whenever a pedestrian circulation system is not required, the following design standards shall apply:

Sidewalks may be required by the Planning/Zoning Board along both sides of culs-de-sac, loop streets, and major collectors.

When the subdivision is within 1/2 mile of a pedestrian attractor which includes commercial establishments, municipal or governmental offices, schools, places of worship, post offices and recreation areas, sidewalks shall be required to allow pedestrian movement to such facilities.

Sidewalks or interior walkways may be required to provide access to environmental amenities within or adjacent to the subdivision.

The Planning/Zoning Board may require sidewalks on both sides of a street near intersections or at such other locations due to pedestrian safety considerations.