Construction and remediation at brownfield sites in densely populated urban-residential areas requires diligence and specific considerations for surrounding receptors.
The presence of chlorinated volatile organic compounds (CVOCs), specifically trichloroethene (TCE), in soil and groundwater at a metro Boston site presented unique challenges during soil excavation activities for an apartment complex. Subsurface investigations included pre-characterization soil sampling to develop a soil management plan and designate the final disposition of soils and installation of monitoring wells to monitor the TCE-impacts in groundwater. The soil data was used to evaluate the anticipated level of off-gassing during excavation of TCE-impacted soils. A ground-level garage was incorporated into the building design to mitigate vapor intrusion risks associated with the TCE-impacted media that remain in place. A comprehensive real-time air quality monitoring program was developed with regulatory input to monitor the wind direction, Total VOCs, and TCE concentrations along the perimeter of the site using a Photoionization Detector and a Frog 4000/5000 portable gas-chromatograph at 15-min increments. The plan included trigger concentrations and contingencies for additional samples to be collected immediately at the surrounding properties and agreements with residences and a middle school for indoor air sampling should the outdoor results exceed the residential imminent hazard level for TCE of 6 µg/m3 (1.1 ppbV). The monitoring was complicated by a trigger concentration set near the reporting level of the unit (5.37 µg/m3 [1 ppbV]). The factory-calibration of the unit, including retention time was checked several times a day using a custom formulated TCE gas at a concentration of 26.3 µg/m3 (4.9 ppbV). The project serves as an example of a successfully executed residential excavation with close receptors, significant regulatory involvement, and real-time monitoring. The construction activities have been completed and the site is currently on track for closure under the state regulatory program in early 2020.
- Geosyntec Authors: Dariusz Chlebica, Jessica Yeager, Zach Grosso
- All Authors: Dariusz Chlebica, Jessica Yeager, Zach Grosso
- Title: 36th Annual International Conference on Soils, Sediments, Water, and Energy
- Event or Publication: Event
- Practice Areas: Air Quality Management and Air Pollution Control
- Citation: Multiple Geosyntec practitioners will present at the virtual 36th Annual International Conference on Soils, Sediments, Water, and Energy on October 19-23, 2020.
- Date: October 19-23, 2020
- Location: Virtual
- Publication Type: Poster Presentation