In situ remediation is the overall term for an accepted suite of technologies that are useful in remediation of polluted sites. In situ remediation treats pollution "in place", below the ground surface and without significant disturbance. Physical extraction, biologic activity, chemical modification, or other processes are employed to remove, degrade or stabilize pollutants in soil and groundwater. In many instances, this result is accomplished through the introduction of substances into the subsurface of a site. This discharge of substances intended to change groundwater quality requires a permit from DEP. DEP has developed a general permit for the most common in situ remedial activity - enhanced aerobic biodegradation. In situ remedial activities not covered by a general permit may still be authorized through the issuance of an individual groundwater discharge permit or a temporary discharge authorization, as appropriate for the proposed activity. 

In Situ Groundwater Remediation: Enhanced Aerobic Biodegradation (DEP-REM-GP-001)

Fact Sheet

The General Permit for In Situ Groundwater Remediation: Enhanced Aerobic Biodegradation authorizes oxygenation of groundwater at a controlled rate to enhance in situ aerobic degradation of organic pollutants and allows use of several different sources of oxygen and delivery methods. Supplemental nutrients or cultured bacteria may also be added under the general permit framework. Chemical oxidation of pollution is not authorized under this general permit; and the permit incorporates limits on ozone and hydrogen peroxide to ensure their use solely as an oxygen source for biodegradation.

Registration must be submitted to the department and approved for activity to be authorized pursuant to this general permit. Qualitative or quantitative evidence of pollution is required for any authorization pursuant to a general permit for in-situ remediation. The general permit allows for DEP issuance of a certificate of coverage in lieu of an approval of registration for authorization of certain activities, and also provides for limited self-implementation upon registration.

Groundwater monitoring is typically required, especially for potentially affected supply wells. The monitoring objective is to document that groundwater quality outside the delineated zone of influence is not affected. Additional monitoring may be needed to verify that remedial objectives are met. The environmental professional is required to evaluate monitoring data to determine and report any indications of unexpected outcomes and mitigation is required for adverse conditions caused by the discharge. Reporting and recordkeeping requirements for discharge and monitoring activities are specified, and combined reporting is allowed when reporting is also required under DEP remedial program requirements.