N.J. Admin. Code § 7:14A-13.5 - Determination of the reasonable potential to cause an excursion above the SWQS as a basis for requiring inclusion of water quality based effluent limitations

(a) Water quality based effluent limitations shall control all pollutants or pollutant parameters (either conventional, nonconventional, or toxic pollutants, including whole effluent toxicity) which are or may be discharged at a level which will cause, have the reasonable potential to cause, or contribute to an excursion above the Surface Water Quality Standards.

(b) When determining whether a discharge causes, has the reasonable potential to cause, or contributes to an instream excursion above any Surface Water Quality Standard the Department shall evaluate and consider existing controls on point and nonpoint sources of pollution, the variability of the pollutant or pollutant parameter in the effluent, the sensitivity of the test species to toxicity testing (when evaluating whole effluent toxicity), and, where appropriate, the available dilution of the effluent in the receiving water.

(c) The dilution of the effluent in the receiving water shall be determined in accordance with 7:9B-1.5(h).

(d) A separate determination of reasonable potential shall be made for each pollutant or pollutant parameter of interest (either conventional, nonconventional, or toxic pollutants, including acute and chronic whole effluent toxicity) that is or may be discharged from the facility. These determinations shall be based on a WLA or site specific allocation.

(e) The discharge shall be determined to cause an excursion above the Surface Water Quality Standards if the maximum reported effluent concentration, considering the criteria averaging period, for the pollutant of interest is greater than the WLA or the site specific allocation for that pollutant.

(f) The discharge shall be determined to contribute to an excursion above the Surface Water Quality Standards if the maximum reported effluent concentration, considering the criteria averaging period, for the pollutant of interest when considered collectively with other discharges to the receiving water is greater than the WLA determined for that pollutant.

(g) The discharge shall be determined to have the reasonable potential to cause an excursion above the Surface Water Quality Standards if the maximum projected effluent concentration is greater than the WLA or site specific allocation determined for that discharge for that pollutant or pollutant parameter. The maximum projected effluent concentration shall be calculated in accordance with the USEPA TSD, as amended and/or supplemented, unless the permittee demonstrates for a given pollutant of interest that none of the methods in the TSD are applicable and that an alternative statistical method more accurately estimates the maximum projected effluent concentration.

(h) Where an effluent concentration is directly caused by a documented facility upset, or other unusual event which has been identified and appropriately remedied by the permittee, data collected during the period of upset may be eliminated when making a determination of reasonable potential. Data no longer representative of effluent quality because of process modification or pollution prevention activities undertaken shall not be used when making a determination of reasonable potential.

(i) (Reserved)

(j) (Reserved)

(k) When the Department determines that a discharge does not cause, have reasonable potential to cause, or contribute to an excursion above the water quality standards for a specific pollutant or pollutant parameter; or that data are insufficient to make such a determination:

1. Except as specified in (k)1i through iii below, water quality based effluent limitations shall not be required for that pollutant or pollutant parameter.

i. Where the discharge is in compliance with an existing water quality based effluent limitation and the permittee provides treatment for the limited pollutant or pollutant parameter , the reissued permit shall include a water quality based effluent limitation for the affected pollutant or pollutant parameter unless the permittee demonstrates to the satisfaction of the Department that a water quality based limitation is no longer required and that the existing effluent quality is anticipated to be maintained.

ii. When the Department determines in accordance with (k)1i above that a water quality based effluent limitation is not required for the reissued permit, the fact sheet for the reissued permit shall include a summary of effluent data for the pollutant or pollutant parameter, a justification for eliminating the effluent limitation, and a determination that eliminating the effluent limitation is not anticipated to cause or contribute to an exceedance of the surface water quality standards.

iii. When the Department determines in accordance with (k)1i above that a water quality based effluent limitation is not required for the reissued permit, the discharge permit shall be reopened and modified to include water quality based effluent limitations if the effluent quality changes so as to cause, contribute, or have the reasonable potential to cause or contribute to an excursion above the Surface Water Quality Standards.

iv. The Department shall consider the following factors when making a determination regarding reasonable potential for discharges with existing water quality based effluent limitations:

(1) The permit compliance history for the facility, including the compliance history for the specific pollutant or pollutant parameter and any permit conditions related to the pollutant or pollutant parameter;

(2) The reliability of the treatment process; and

(3) The ratio between the permitted or actual effluent flow and the base flow of the receiving water;

2. Effluent limitations other than water quality based limitations may be required for the pollutant or pollutant parameter in accordance with 7:14A-13.3; and

3. The Department may determine that monitoring for specific pollutant or pollutant parameters shall be included in the permit.

(l) When the Department is unable to determine for one or more pollutants or pollutant parameters of interest whether the discharge from a particular facility will cause, have the reasonable potential to cause, or contribute to an excursion above a Surface Water Quality Standard, the permit for that facility shall include effluent monitoring requirements for each pollutant or pollutant parameter where such a determination cannot be made. The discharge permit shall be reopened and modified to include water quality based effluent limitations if subsequent monitoring demonstrates that the discharge causes, contributes, or has the reasonable potential to cause or contribute to an excursion above the Surface Water Quality Standards.

(m) For a facility that discharges any pollutant which is present in the process intake water, the Department may, on a site specific basis, determine that the discharge does not cause, have reasonable potential to cause, or contribute to an excursion above the water quality standards in accordance with the following:

1.

(Reserved)

2.

(Reserved)

3. The discharge shall meet the following conditions:

i. The source for all of the intake water shall be the receiving water body. Hydrologically connected waterbodies may be determined to be the same waterbody if the water is completely mixed within a reasonable distance of the outfall location and if the chemical characteristics of the waterbodies are essentially identical. Chemical characteristics may be evaluated on a parameter by parameter basis. For discharges where the intake water is attributed to more than one source, this condition may be applied to the proportion of the intake water attributable to the receiving water or hydrologically connected waterbody;

ii. The discharge shall not contribute any additional mass of the pollutant of interest to the process intake water. This determination shall be based on a statistically rigorous analysis of intake water and outfall data that is representative of various operating conditions and influences over time and demonstrates that there is no significant difference at the 99th percent probability level between the intake concentrations and loadings and the outfall concentrations and loadings. For a DTW, this condition shall be deemed to be met if there is no significant difference at the 99th percent probability level between the intake concentrations and loadings of the public drinking water supply in the area served and the effluent concentrations and loadings. Where the source water is attributed to more than one water supply source, this condition may be applied to the proportion of the source water attributable to the receiving water or hydrologically connected waterbody;

iii. The discharger shall not chemically or physically alter the intake water to cause an adverse impact to the receiving stream for any pollutant of interest in the process intake water;

iv. The pollutant shall not accumulate at the outfall location or at the edge of the mixing zone in such a way as to increase the concentration of the pollutant. The Department may require submission of an acceptable mixing zone study to satisfy this requirement; and

v. The timing and/or location of the discharge shall not cause adverse impacts in the receiving waterbody that would not have occurred if the pollutant had remained in the waterbody.

4. The permit shall include the necessary monitoring conditions to ensure continuing compliance with the conditions listed in (m)3 above.

5. The discharge permit shall be reopened and modified to include water quality based effluent limitations if subsequent monitoring demonstrates that the discharge causes, contributes, or has the reasonable potential to cause or contribute to an excursion above the surface water quality standards at N.J.A.C. 7:9B.

6. The permit fact sheet shall include a description of the treatment process and specific reasons for making the determination that the discharge does not cause, have reasonable potential to cause or contribute to an excursion above the water quality standard for the pollutants or pollutant parameters subject to this subsection.

7. For any pollutant or pollutant parameter where the conditions listed in (m)3 above cannot be met, reasonable potential shall be determined in accordance with (d) through (k) above.

8. For site remediation projects, reasonable potential shall be determined in accordance with this subsection only for pollutants not subject to remediation.

Notes

N.J. Admin. Code § 7:14A-13.5

Administrative correction.
See: 29 N.J.R. 3822(a).
Amended by R.2009 d.372, effective 12/21/2009.
See: 41 N.J.R. 1565(a), 41 N.J.R. 4735(a).
In (c), updated the N.J.A.C. reference.