Site design features identified under Article
IV, §
179-12B above, or alternative designs in accordance with Article
IV, §
179-13 above, to prevent discharge of trash and debris from drainage systems, shall comply with the following standard to control passage of solid and floatable materials through storm drain inlets. For purposes of this section, "solid and floatable materials" means sediment, debris, trash, and other floating, suspended, or settleable solids. For exemptions to this standard see Subsection B below.
A. Grate.
(1) Types. Design engineers shall use one of the following grates whenever
they use a grate in pavement or another ground surface to collect
stormwater from that surface into a storm drain or surface water body
under that grate:
(a)
The New Jersey Department of Transportation (NJDOT) bicycle-safe
grate, which is described in Chapter 2.4 of the NJDOT Bicycle Compatible
Roadways and Bikeways Planning and Design Guidelines; or
(b)
A different grate, if each individual clear space in that grate
has an area of no more than 7.0 square inches, or is no greater than
0.5 inch across the smallest dimension.
(2) Examples.
(a)
Examples of grates subject to this standard include grates in
grate inlets, the grate portion (non-curb-opening portion) of combination
inlets, grates on storm sewer manholes, ditch grates, trench grates,
and grates of spacer bars in slotted drains.
(b)
Examples of ground surfaces include surfaces of roads (including
bridges), driveways, parking areas, bikeways, plazas, sidewalks, lawns,
fields, open channels, and stormwater system floors used to collect
stormwater from the surface into a storm drain or surface water body.
(3) For curb-opening inlets, including curb-opening inlets in combination
inlets, the clear space in that curb opening, or each individual clear
space if the curb opening has two or more clear spaces, shall have
an area of no more than 7.0 square inches, or be no greater than 2.0
inches across the smallest dimension.
B. The standard in Subsection
A above does not apply:
(1) Where each individual clear space in the curb opening in existing
curb-opening inlet does not have an area of more than 9.0 square inches;
(2) Where the municipality agrees that the standards would cause inadequate
hydraulic performance that could not practicably be overcome by using
additional or larger storm drain inlets;
(3) Where flows from the water quality design storm as specified in N.J.A.C.
7:8 are conveyed through any device (e.g., end-of-pipe netting facility,
manufactured treatment device, or a catch basin hood) that is designed,
at a minimum, to prevent delivery of all solid and floatable materials
that could not pass through one of the following:
(a)
A rectangular space 4 5/8 (4.625) inches long and 1 1/2
(1.5) inches wide (This option does not apply for outfall netting
facilities.); or
(b)
A bar screen having a bar spacing of 0.5 inch.
Note that these exemptions do not authorize any infringement
of requirements in the Residential Site Improvement Standards for
bicycle-safe grates in new residential development [N.J.A.C. 5:21-4.18(b)2
and 21-7.4(b)1].
(4) Where flows are conveyed through a trash rack that has parallel bars
with one-inch spacing between the bars, to the elevation of the water
quality design storm as specified in N.J.A.C. 7:8; or
(5) Where the New Jersey Department of Environmental Protection determines,
pursuant to the New Jersey Register of Historic Places Rules at N.J.A.C.
7:4-7.2(c), that action to meet this standard is an undertaking that
constitutes an encroachment or will damage or destroy the New Jersey
Register listed historic property.