N.J. Admin. Code § 7:10-11.13

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

Section 7:10-11.13 - Pretreatment requirements

(a) General regulations for pretreatment are as follows:

1. The number of pretreatment units shall be such that when any single unit is out of service the remaining pretreatment unit(s) comply with the detention time and surface loading rate requirements of this section for at least the average daily demand on the treatment plant. A minimum of two pretreatment units is required for surface water treatment.

2. Sufficient data shall be included in the engineer's report submitted pursuant to 7:10-11.5 to establish the type and application rate of the chemicals required for pretreatment.

3. Each pretreatment basin shall be equipped with a drain or drains to facilitate dewatering.

4. Adequate provision shall be made for the removal of sludge. Where sludge is expected to be voluminous, consideration should be given to mechanical methods of removal.

5. Water treatment sludge shall be disposed of in accordance with applicable State and Federal law and regulations.

(b) Pretreatment chemicals shall be applied to water where there is sufficient agitation to ensure rapid and uniform dispersion of each chemical throughout the water, such as at pump suctions, rapid mix basins or static mixers.

(c) Regulations for flocculation are as follows:

1. Flocculation is required for all surface waters.

2. Flow-through velocities shall not be less than 0.5 feet per minute or greater than 1.5 feet per minute, with a detention time for floc formation of not less than 30 minutes.

3. Flocculation shall be accomplished by agitation under mixing conditions. Agitators shall be driven by variable speed drives, with the peripheral speed of paddles ranging from 0.5 to 3.0 feet per second.

4. The flocculation unit shall have compartments and inlet and outlet facilities to minimize short-circuiting and to permit floc to pass from the flocculator to the subsequent treatment unit without impairment. The velocity of flocculated water through pipes or conduits to settling basins shall not be less than 0.5 or greater than 1.5 feet per second.

5. Flocculation (or reaction) time for solids contact units shall be calculated on the basis of the input flow and the volume occupied by the agitated mixture of slurry with the water being treated. For horizontal flow units, the calculation shall be based on the volume of the flocculation or reaction chamber.

(d) Regulations for sedimentation are as follows:

1. Pretreatment by sedimentation is required for all surface waters, unless pilot test data submitted pursuant to 7:10-11.8(d)1 demonstrate that sedimentation pretreatment is not necessary.

2. The minimum depth of the sedimentation basin shall be 10 feet, with ample allowance for sludge accumulation or sludge removal equipment and a depth of water flow of at least six feet.

3. Inlet and outlet facilities shall be designed so as to minimize short-circuiting. Submerged inlet ports shall be located so as to avoid creating a disturbance of the settled floc.

4. The maximum surface loading rates (gallons per minute per square foot) are as follows:

	Flocculation
	or Iron
	or Manganese	Lime
	Removal	Softening
Ground Water	0.5	1.0
Surface Water	0.375	0.75

5. For around-end baffling in a horizontal plane, the maximum surface loading rate pursuant to (d)4 above shall be reduced by 50 percent.

6. For horizontal units, the minimum detention time shall be four hours for surface water and two hours for lime softening treatment plants.

7. The water velocity through settling basins shall not exceed 0.5 feet per second.

8. The Department may approve the use of tube or plate settlers if justification is provided for reduced detention times. In such cases, a pilot plant study shall be implemented to demonstrate satisfactory operation.

i. Sufficient freeboard shall be provided above the top of the settlers to prevent freezing of the units in outdoor installations. The construction of outdoor units is discouraged.

ii. The maximum surface loading rate shall not exceed two gallons per minute per square foot of horizontal tube settler area.

9. Outlet weir loadings shall not exceed 20 gallons per minute per foot of length of settled water. When orifices are used rather than weirs, their size, number and arrangement shall be such as to produce loadings equivalent to the requirements for weirs. Weirs or orifices shall be arranged to produce uniform flow rates over the area of the sedimentation tank.

(e) Regulations for solids-contact units are as follows:

1. Solids-contact units for flocculation, lime softening, iron or manganese removal, and for settling.

2. Solids-contact units shall be installed and initially operated under the supervision of the manufacturer's representative.

3. Each solids-contact unit shall facilitate satisfactory flocculation of the water before it enters the settling area.

4. Surface loading rates for solids-contact units shall be calculated on the basis of the input flow and the horizontal area of flow in the clarification zone at a level five feet below the level of the discharge weirs or orifices. The maximum surface loading rates (gallons per minute per square foot) are as follows:

	Flocculation
	or Iron
	or Manganese	Lime
	Removal	Softening
Ground Water	1.0	2.0
Surface Water	0.75	1.5

5. Each solids-contact unit shall be equipped with sampling taps to facilitate collection of water samples from various locations within the unit to ensure its efficiency.

6. Outlet weir loadings shall not exceed 20 gallons per minute per foot of length of softened water, or 10 gallons per minute per foot of length of flocculated water. Where orifices are used rather than weirs, their size, number and arrangement shall be such as to produce loadings equivalent to the requirements for weirs. Weirs or orifices shall be arranged to produce uniform vertical flow rates over the area of the solids-contact unit.

7. Each solids-contact unit shall be equipped for effective concentration of sludge and to facilitate sludge draw-off and disposal.

8. Sludge piping shall be arranged so as to facilitate operation and cleaning. Piping shall not be less than three inches in diameter and shall allow for flushing with clear water.

9. Sludge valves shall be located outside of the solids-contact tank.

10. Each solids-contact unit shall be equipped to allow manual override of any pre-set automatic intermittent withdrawal of sludge.

N.J. Admin. Code § 7:10-11.13