Leominster, MassachusettsIndoor Air Quality Services
Ambient Engineering was selected by the property management firm of a large, multi-family residential development to assess each apartment for potential radon hazards and, if appropriate, to remediate radon concentrations to acceptable levels. The apartment complex is located in a turn-of-the-century mill complex near downtown Leominster, Massachusetts. The mill buildings were converted to residential units in 1987, after closure of the former manufacturing facility, and an additional 26 multi-level townhouses were constructed on the property.
A radon assessment was performed for the 65 below-grade and on-grade units at the complex. In accordance with US Environmental Protection Agency protocols for short-term radon testing, liquid scintillation charcoal canisters were placed in each unit under closed-building conditions. The units were placed in bedrooms or living areas, away from external influences such as doors, windows, exterior walls, and, heating ducts. Instructions were given to each tenant regarding radon and the radon testing protocol. The canisters were retrieved after 48 hours and submitted to a radon testing laboratory for analysis.
After evaluation of the data, Ambient prepared a report confirming that radon concentrations above the US Environmental Protection Agency action level were present in one apartment in the main complex, and in a second unit in an outlying building. Ambient prepared a specification for radon mitigation in the impacted apartments. Vacuum testing was conducted to determine the potential effectiveness of installing a sub-slab pressurization system and the number of slab penetrations that would be required. Based on the results of these tests, a sub-slab depressurization system, with one slab penetration, was installed in the apartments, under Ambient’s direction. Three-inch diameter vacuum piping was extended to an outside wall of the building, with a Radonaway GP301 fan located at ground level outside of the building for maintenance and access. Post-mitigation testing was conducted to ensure that levels of radon were acceptable after mitigation.
A radon assessment was performed for the 65 below-grade and on-grade units at the complex. In accordance with US Environmental Protection Agency protocols for short-term radon testing, liquid scintillation charcoal canisters were placed in each unit under closed-building conditions. The units were placed in bedrooms or living areas, away from external influences such as doors, windows, exterior walls, and, heating ducts. Instructions were given to each tenant regarding radon and the radon testing protocol. The canisters were retrieved after 48 hours and submitted to a radon testing laboratory for analysis. 
After evaluation of the data, Ambient prepared a report confirming that radon concentrations above the US Environmental Protection Agency action level were present in one apartment in the main complex, and in a second unit in an outlying building. Ambient prepared a specification for radon mitigation in the impacted apartments. Vacuum testing was conducted to determine the potential effectiveness of installing a sub-slab pressurization system and the number of slab penetrations that would be required. Based on the results of these tests, a sub-slab depressurization system, with one slab penetration, was installed in the apartments, under Ambient’s direction. Three-inch diameter vacuum piping was extended to an outside wall of the building, with a Radonaway GP301 fan located at ground level outside of the building for maintenance and access. Post-mitigation testing was conducted to ensure that levels of radon were acceptable after mitigation. 