USACE FUSRAP Maywood Team Develops a Mechanism to Evaluate Residual Radon Exposure Potential at Vicinity Properties Where Remediation of Accessible Contamination has been Completed

The Maywood FUSRAP Team is obligated, under its approved remedy selection decision document, to demonstrate substantive compliance with New Jersey Administrative Code 7:2812(a)2, establishing an indoor limit of three PicoCuries per liter above background for radon-222 (Rn-222). The Maywood Team explores various avenues for dealing with the radon issue and provides an alternative for demonstrating substantive compliance with the radon remediation standard by answering the question: “In certain conservative situations, can compliance with the radon standard be demonstrated without performing monitoring?” While monitoring may be the most definitive method for demonstrating compliance, a logical argument can be made that when radiological remediation removes the potential source for Rn-222 above background, monitoring is unnecessary. This position is defended through the use of historical physical radon measurements which illustrate that indoor radon was not a pre-remediation problem, and postremediation soil sampling data which demonstrate that the source of the potentially elevated Rn222 levels have been successfully mitigated. Monitoring recommendations are made for situations where insufficient data exists to make definitive determinations or when unremediated sources affecting habitable structures remain on a given property. Additional information regarding recommended techniques and references for effective monitoring of indoor radon are included in this paper. This paper may benefit teams that have similar regulatory commitments and/or have need to make assessments of radon exposure potential based upon historical monitoring data and available soils concentration data.