Stop Chasing Contamination: DEP Implements Compliance Averaging Guidance

NJDEP SRP LogoOn September 24, 2012 the NJDEP finalized the Technical Guidance for the Attainment of Remediation Standards and Site-Specific Criteria. The new Guidance provides helpful information for applying appropriate remediation criteria and determining compliance. However, the standout piece of information is that compliance averaging, like the use of 95 percent upper confidence limit of the mean (95 UCL) and 75%/10x, can now apply to Sites in New Jersey. These compliance options have been accepted by the PADEP for years, and REPSG has applied these statistical strategies at many Sites in Pennsylvania.

HOW DOES THIS IMPACT YOUR NEW JERSEY REMEDIATION?

75%/10x is a useful statistical analysis strategy for remediation involving point-source impacts, like underground storage tanks or small spills. As long as the specified number of samples is collected and the analytical results of 75% of those samples are compliant with the remediation standard, the soils under investigation are in compliance. This approach can eliminate the need to chase low-level contamination that can sometimes persist after the removal of a heating oil tank; for example, in the case of benzo(a)pyrene and number 4 fuel oil.

95 UCL is another helpful statistical analysis strategy that can now be utilized at Sites in NJ. This method identifies uniform contamination and estimates the average concentration at the 95 UCL. If the average concentration is below the remediation standard, the associated soils are compliant; even some samples within the dataset have concentrations above the remediation standard.

Do you think that compliance averaging could help speed up remediation at your Site? REPSG can apply our statistical experience to your New Jersey projects. Leave a comment below or please feel free to contact me at jcutright@repsg.com.