New Jersey says averaged sample results cannot close a cleanup until contamination is fully mapped
An October 21, 2026, state notice treats compliance averaging as a remedial action, so investigators must first sample to the edges of contamination and show it on site maps.
Redevelopers of contaminated New Jersey sites who plan to show a cleanup is finished by averaging soil sample results may need more sampling before that approach can support closing the cleanup. On October 21, 2026, the New Jersey Department of Environmental Protection ("NJDEP") issued a notice through its site remediation email list reminding licensed professionals and responsible parties that "full delineation (horizontal/vertical) of contaminants is required when a compliance averaging methodology is selected as part of a remedial action at an area of concern," and pointing to N.J. Admin. Code § 7:26E-5.2(a)(3).
N.J. Dep't of Env't Prot., Requirement to Complete Delineation to Appropriate Remediation Standards When Using Compliance Averaging Methodologies as Remedial Actions (Oct. 21, 2026); N.J. Admin. Code §§ 7:26E-1.6(b)(8)(ii), 7:26E-5.2(a)(3)