N.J. Admin. Code § 7:14A-23.15 - Screening and comminution

(a) All sewage treatment plants shall be provided with a means for screening or comminuting coarse material in the sewage. Except in small plants with a design capacity of less than 150,000 gallons per day, screening equipment shall be of the mechanical type.

(b) Operation of mechanically cleaned devices shall be continuous or automatically controlled.

(c) Bar screens shall conform to the following:

1. Bars of nonmechanical screens preceding treatment plants shall be spaced so that the maximum clearance between bars is not greater than 1 1/2 inches and not less than one inch;

2. Clear openings for mechanically cleaned screens shall not be less than 5/8 inch;

3. Bar clearance for coarse racks or screens preceding mechanically cleaned screens or comminutors shall not exceed 1 3/4 inches;

4. At sewage pumping stations, openings in bar screens shall be at least one inch smaller than the solid size which can be handled by the pump;

5. Motors shall be of the type suitable for operation in a damp atmosphere if placed below ground;

6. The screen chamber shall be designed to provide a velocity through the screen of not less than one foot per second at average flow and not more than three feet per second, based on the screen openings projected vertically between the invert and the crown;

7. Hand-cleaned screens shall be inclined from 30 degrees to 45 degrees from horizontal; and

8. Where only one mechanical screen is provided, auxiliary hand-cleaned screens shall be provided for use in case of failure of the mechanically cleaned screens.

(d) Disposal of screenings shall be in conformance with the following:

1. Adequate facilities shall be provided for prompt removal, handling and sanitary disposal of screenings;

i. A platform shall be provided at the top of hand-raked screens; and

ii. Appropriate containers shall be provided for removal of screenings;

2. An appropriate method shall be provided for drainage of screenings, both on the platform and in containers, such that water content is not a limitation to ultimate disposal. The disposal and treatment method for the drainage from the screenings shall be indicated;

3. Where screen chambers are located substantially below grade, a suitable hoist shall be provided. Such chambers shall have a stairway and adequate lighting; and

4. Screen chambers shall be adequately ventilated. Where required, forced draft fans with explosion-proof motors shall be installed.

(e) Comminutors shall be in conformance with the following:

1. Comminuting devices shall have slots not less than 1/4 inch wide and be designed to cut or shred material below the surface of the sewage. Comminuting capacity shall be adequate to handle peak flows when the largest unit is out of operation;

2. A bypass screen shall be provided except where there are multiple units; and

3. Gates shall be provided to isolate each channel, and provisions shall be made for the removal of mechanisms for repair and maintenance.

Notes

N.J. Admin. Code § 7:14A-23.15