New Jersey Administrative Code › Title 19 - OTHER AGENCIES › NEW JERSEY MEADOWLANDS COMMISSION › Chapter 5 - SUBDIVISION REGULATIONS › Subchapter 7 - DESIGN STANDARDS › Section 19:5-7.8 - Drainage

Current through Register Vol. 56, No. 14, July 15, 2024
(a) Each
				  subdivision submitted shall be reviewed by the NJMC to ensure the adequacy of
				  all drainage provisions proposed within said subdivision and that potential
				  adverse drainage conditions on all adjoining property resulting from such
				  development have been addressed appropriately.
(b) Drainage systems shall be designed in
				  accordance with
				  19:4-8.6.
(c) In addition to the requirements of
				  19:4-8.6, the following shall
				  apply to drainage systems in proposed ROWs and subdivision drainage easements:
1. All pipeline and open channel drainage
				  systems shall be designed to convey the maximum discharge commensurate with
				  design.
2. Pipes shall be
				  considered "flowing full" at maximum capacity.
3. Minimum design velocity of "flowing full"
				  condition for drainage piping shall be two feet per second, or as otherwise
				  approved on a case-by-case basis by the NJMC.
4. For drainage systems utilizing pipes that
				  are 48-inch pipelines and larger, vertical and horizontal deflections may
				  utilize 100-foot, or greater, radius curves.
5. The spacing between inlets shall not
				  exceed 400 feet or a design inlet flow of six cubic feet per second; whichever
				  condition shall be more stringent. Access manholes shall be spaced at a maximum
				  of 400 feet intervals through ROWs and at pipe junctions where there are no
				  catch basins. However, a recommended spacing length shall be 300 feet to allow
				  for easier access to pipes for inspection and maintenance.
6. "Dish" street intersections shall not be
				  permitted. Sufficient catch basins shall be installed at street intersections
				  and low points in the street to avoid gutter overflow.
7. Reinforced concrete pipe shall be utilized
				  in ROWs and shall have appropriate cover for the design load
				  proposed.
8. Catch basins and
				  manholes shall be constructed in accordance with New Jersey Department of
				  Transportation Standard Specifications for Road and Bridge Construction, 2001
				  Edition, incorporated herein by reference, as amended and supplemented, which
				  can be obtained from the New Jersey Department of Transportation, 1035 Parkway
				  Avenue, PO Box 600, Trenton, NJ 08625-0600. Castings shall conform to NJDOT
				  Standard Specification for Road and Bridge Construction.
9. Permissible design velocities in open
				  channels shall be as follows:
Table 5-4
Permissible Design Velocities in Open
						  Channels
Excavation Material
Velocity
						  (fps)
Fine sand to firm loam
2.0 to 3.0
Stiff clay to hardpan
3.0 to 5.0
Concrete lined ditch
10 (maximum)
10. Channel
				  and ditch banks shall be protected by use of vegetation and/or rip rap as
				  design velocity dictates.
11. The
				  minimum Manning's roughness coefficient "n," used in the Manning's equation
				  listed in 19:4-8.6(b)4  i,
				  shall be as follows for the calculation of discharge flows in open channels:
Table 5-5
Minimum Manning's Roughness Coefficient "n"
						  Used in the
Calculation of Discharge Flows in Open
						  Channels
Channel Type and
						  Condition
Manning's "n"
Concrete lined ditch--good condition
0.013
Unlined ditch--good condition
0.025
Natural streams and watercourses--fair to
0.030
						  to 0.150
poor condition
12. If an
				  alternative flow formula is used, discharge coefficients shall be equivalent to
				  the Manning's roughness coefficient "n" specified in (c)11 above.