N.J. Admin. Code § 7:9A-9.4

Current through Register Vol. 56, No. 21, November 4, 2024

Section 7:9A-9.4 - Distribution boxes

(a) A distribution box shall be required for all gravity flow systems and all gravity dosing systems where the effluent shall be distributed between two or more separate distribution laterals. The following requirements shall be met:

1. Distribution boxes shall be water-tight and constructed of sound and durable materials which will resist decay or corrosion by sulphuric acid, frost damage, cracking or buckling due to backfilling or other anticipated stresses.

2. The distribution box shall be set perfectly level and shall be installed as follows:

i. In the case of disposal beds, the distribution box shall be installed directly on the filter material within the disposal bed.

ii. In the case of disposal trenches, the distribution box shall be set on a layer of gravel or a concrete footing extending downward below the maximum expected depth of frost penetration. Where gravel is used, the gravel shall extend laterally a minimum of six inches beyond the sides of the distribution box.

3. A separate outlet shall be provided for each distribution lateral. The inverts of all outlets shall be securely set at the same level which shall be a minimum of two inches above the bottom of the box. When installation is complete the distribution box shall be filled with water at which time the installation shall be checked to make sure that it is level. Adjustments shall be made as necessary so that all outlets are permanently and securely fixed at exactly the same elevation prior to backfilling.

4. The invert of the inlet shall be at least one inch above the invert of the outlets. Where dosing is employed, or where the connecting pipe from the pre-treatment unit has a steep slope, measures shall be taken to prevent direct flow of effluent across the distribution box resulting in unequal distribution of effluent among the distribution box outlets. This may be accomplished by installation of a baffle or elbow within the distribution box or by use of two distribution boxes connected in series. In the latter case, all outlets of the first distribution box shall be sealed off except for the outlet which discharges to the second distribution box.

5. Distribution boxes shall be provided with a means of access which may be a removable lid in the case of smaller boxes. Access to larger boxes may be provided by means of manholes and inspection ports with removable water-tight covers. In any case, the following requirements shall be met:

i. Access openings must be adequate in size and located to facilitate removal of accumulated solids and inspection of the inlet and all outlets.

ii. All access openings shall be extended to within 12 to 18 inches of the finished grade surface.

iii. Access openings shall be constructed in such a manner as to prevent the entrance of surface water.

N.J. Admin. Code § 7:9A-9.4

Amended by R.1999 d.314, effective 9/20/1999.
See: 31 N.J.R. 1416(a), 31 N.J.R. 2741(a).
In (a)3, substituted "securely" for "rigidly" following "shall be' in the first sentence.
Amended by R.2012 d.066, effective 4/2/2012.
See: 43 N.J.R. 478(a), 44 N.J.R. 1047(a).
In the introductory paragraph of (a), inserted "separate", and deleted "which are not inter-connected" following "laterals".