Targus was retained to perform an environmental site assessment (Phase I ESA and additional non-ASTM services) of a recently-constructed apartment property. As an additional service, Targus conducted short-term screening of a subset of the ground-contact dwelling units for radon.
A substantial minority of units were found to exceed the EPA Action Level of 4.0 picoCuries per liter of air (pCi/L). In an effort to secure more reliable indicators of average radon concentrations, long-term post-closing testing was conducted. Replicate detectors retrieved after a six-month exposure period confirmed elevated radon levels in a subset of units tested, including those that were found to be elevated during the initial screening. An additional round of testing was conducted over a period of 12 months in the units that previously had average radon concentrations exceeding 3.0 pCi/L.
Elevated radon concentrations were consistently detected in certain individual buildings and were absent in others. In light of the widespread radon in small (typically four units) problem buildings, and predictable performance, interior pressurization was selected as the remedy.
Targus engaged a building contractor to install piping from heating, ventilation, and air conditioning (HVAC) closets to louvers in exterior walkways and installed small fans with timer controls connected to the return ducts. Following these early adjustments, radon concentrations were demonstrated through subsequent long-term testing to have been reduced to below 4.0 pCi/L.