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Proposed Changes to New Jersey Groundwater Standards
On January 2, 2024, NJDEP published a proposed rulemaking that contains significant changes to the Ground Water Quality Standards (GWQS) promulgated at N.J.A.C. 7:9C. The proposed revised standards are applicable to Class II-A groundwater designated for potable use, which is the default designation for all groundwater in New Jersey. As such, these standards frequently dictate the allowable concentration of chemicals in groundwater at remediation sites and for NJPDES Discharge to Groundwater permits. The proposed changes include significant reductions to many of the GWQS and are expected to result in increased remediation costs as well as reevaluation and potentially additional remediation at previously closed sites.
The proposed rulemaking includes changes to the health-based Groundwater Quality Criteria based on updated toxicological information, changes to the Practical Quantitation Levels (PQLs) that can be reliably achieved by groundwater testing laboratories, changes to numeric rounding procedures, and additional statutory language that will allow NJDEP to more quickly enact these changes in the future by referencing drinking water standards already promulgated.
The GWQS for each chemical is based on the higher of the health-based Groundwater Quality Criteria and the PQL. A reduction in the GWQS may therefore result from a reduction in the Groundwater Quality Criterion (indicating the chemical is more toxic than previously thought), or from a reduction in the PQL (indicating the chemical is now measurable at lower concentrations), or both. We’ve noted substantial reductions in the proposed PQLs for many compounds which, in practice, may or may not be achievable by most laboratories using common analytical methods. The resulting GWQS will dictate the allowable concentration of the chemical in Class II-A groundwater at remediation sites and for permitted discharges to groundwater. Of the 65 proposed GWQS, 50 will become more stringent, and 13 will become less stringent.
Additionally, New Jersey’s Site Remediation Program requires remediators to reevaluate previously closed sites for chemicals where any applicable GWQS has been reduced by an order of magnitude or more. This reevaluation will, at a minimum, extend the aerial extent and duration of Classification Exception Areas (CEA) used to prevent use of contaminated groundwater, and in many cases may require additional groundwater remediation to meet the reduced GWQS. The changes also have the potential to increase natural resource damage penalties calculated by NJDEP. The following GWQS are proposed to decrease by an order of magnitude or more:
| Chemical | Current GWQS (ug/L) | Proposed GWQS (ug/L) |
| 1,1-biphenyl | 400 | 5.0 |
| Cobalt | 100 | 2 |
| Cyanide (free) | 100 | 5.0 |
| 1,3-dichlorobenzene | 600 | 5 |
| Heptachlor epoxide | 0.2 | 0.020 |
| Methoxychlor | 40 | 0.1 |
| Vinyl chloride | 1 | 0.035 |
NJDEP is aware of thousands of remediation sites, both active and closed, that are contaminated by one of these seven chemicals, and expects the proposed GWQS reductions to have potentially significant economic impacts on these sites.
A virtual public hearing on the proposed rulemaking has been scheduled for January 30, 2024, and written comments on the proposed rulemaking may be submitted electronically until March 2, 2024. If you are interested in learning more about the proposed changes, wish to submit comments, or want to better understand how these changes may impact your ongoing or previously completed remediation project, please contact Michael Dillon or one of our in-house technical consultants.
