N.J. Admin. Code § 7:14A-8.18

Current through Register Vol. 56, No. 19, October 7, 2024

Section 7:14A-8.18 - Specific operating criteria and construction standards applicable to permit by rule authorizations for underground injection into seepage pits

(a) This section sets forth the operating criteria and construction standards for underground injection into seepage pits under a permit-by-rule pursuant to 7:14A-8.5(b)4 or 5.

(b) Design requirements are as follows:

1. When required to protect against accumulation of fine particles that would impair the proper functioning of the seepage pit, a multiple compartment septic tank shall be designed and constructed in accordance with 7:9A-8.2.

2. The percolating area shall be the total outside surface area of the seepage pit lining below the inlet and exclusive of any soil horizons with a percolation rate slower than 40 minutes per inch. The bottom of the seepage pit shall not be counted as part of the percolating area. The minimum percolating area shall be determined from the following table based upon the maximum daily volume of discharge and a weighted average of the percolation or permeability rates of all soil layers exposed in the sidewalls. In no case, however, shall the percolating area be less than 110 square feet.

Minimum Area Required for Seepage Pits, Based on One
Gallon Liquid Per Day, and Based on the Percolation Rate of the Soil
Average Percolation Rate	Minimum Area Per Gallon Per Day
(Min/inch)	(Square feet)
10 or less	0.48
11 to 20	0.72
21 to 30	0.96
31 to 40	1.20
over 40	not acceptable

(c) Construction requirements are as follows:

1. Seepage pits shall be constructed within an excavation affording adequate working space and shall be constructed of stone, brick, cinder, precast concrete or concrete block, or similar material laid dry with open joints where permeable strata have been penetrated, except that if the seepage pit is not of circular construction or if the surrounding ground is subject to cave-in, all horizontal joints shall be mortared so as to prevent structural failure. The following requirements shall be met:

i. All joints above the inlet, in all cases, shall be made watertight;

ii. Before placement of backfill, all sidewall areas shall be scarified; and

iii. The bottom of the seepage pit shall be filled with coarse gravel to a depth of one foot unless the bottom is in a sand or gravel formation.

2. Seepage pits shall be backfilled according to the following procedure:

i. The space between the excavation and the seepage pit wall shall be backfilled with at least three inches of coarse gravel or filter material meeting New Jersey Department of Transportation's standards for coarse aggregate sizes 3, 4 and 24.

ii. Where cinder or concrete blocks are laid with core openings exposed, the space between the excavation and seepage pit wall shall be backfilled with at least six inches of two and one-half inch crushed stone or gravel.

iii. Backfill above the inlet shall be of earth similar to that found at the site which is free from large stones, tree stumps, broken masonry or waste construction material, and shall be thoroughly compacted by hand or mechanical tamping methods. The use of heavy machinery for this purpose is prohibited.

3. Covers shall be constructed of reinforced concrete, shall be a minimum of three inches in thickness, watertight, and shall be designed and constructed so as not to be damaged by any load which is likely to be placed upon them.

4. At least one access opening with a removable, watertight cover and a minimum dimension of 24 inches shall be provided. Access openings shall meet the following requirements:

i. Access shall be adequate to permit pumping out of the pit as well as inspection and maintenance of the inlet;

ii. When the cover of the seepage pit is deeper than 12 inches below finished grade, the access opening shall be extended to within 12 inches of finished grade by means of a concrete riser with cast-iron manhole cover;

iii. When the access opening is below finished grade, a permanent marker at finished grade shall be provided to indicate its location; and

iv. When the access opening is at or above finished grade, the cover shall be bolted, locked or otherwise secured to prevent access by children.

(d) Requirements for the submission of certifications are as follows:

1. Any facility qualifying for this permit by rule shall submit an as-built certification from a New Jersey licensed professional engineer which certifies that the system was designed and constructed in accordance with the requirements of this section. The certification and a NJPDES-1 form shall be submitted within 30 days of the completion of construction to:

NJDEP

Division of Water Quality

Bureau of Nonpoint Pollution Control

PO Box 029

Trenton, New Jersey 08625-0029

N.J. Admin. Code § 7:14A-8.18

Amended by R.2004 d.47, effective 2/2/2004.
See: 35 N.J.R. 169(a), 35 N.J.R. 1331(a), 36 N.J.R. 813(a).
In (d), updated address.
Amended by R.2009 d.7, effective 1/5/2009.
See: 40 N.J.R. 1478(a), 41 N.J.R. 142(a).
In (a), updated the N.J.A.C. reference.