Ambient Air Monitoring MGP Site Adjacent to Missouri State Capitol

Ameren Services Company had an electrical substation and storage facility located on a site once used as a coal-gasification plant.

Coal tar residue, a by-product of the coal gasification process, contaminated the soil at the site. The site was located in an environmentally-sensitive area near the Missouri River, at the foot of the Missouri State Capitol building. Ameren retained GEI to conduct perimeter ambient air monitoring during the MGP remediation activities at the site.

GEI developed a comprehensive Ambient Air Monitoring Plan (AAMP) and a Quality Assurance Project Plan (QAPP) for this project. We developed site-specific, risk-based ambient air quality standards for this site. We based our standards on the project’s expected duration and human health risks from specific CPCs, or contaminants of potential concern, identified for both the surface and subsurface soils.

GEI was responsible for the design, installation, operation, calibration, and maintenance of the real-time and time-integrated air monitoring equipment at four stations along the perimeter of the project site.

The real-time air monitoring system included a combination of “fixed” air monitoring stations to continuously measure concentrations of volatile organic compounds (VOCs) and particulate matter less than 10 micron in aerodynamic size (PM10). The real-time stations operated 24 hours a day, 7 days a week.

The time-integrated air monitoring system included operation of four stations, each equipped with sampling equipment designed to collect integrated ambient air samples for VOCs, polynuclear aromatic hydrocarbons (PAHs) and PM10 over a 72-hour sampling period. The use of 72-hour sampling periods dramatically reduced the total number of samples analyzed, thus reducing the overall cost of the ambient air-monitoring program. The time-integrated sampling system also operated 24 hours a day, 7 days a week for the 4 ½-month duration of the project. On-site meteorological data was also collected.

We conducted this project in conjunction with the research we performed on behalf of the Electric Power Research Institute (EPRI), collecting data to evaluate the effectiveness of the real-time system.

GEI was responsible for providing daily air monitoring reports to the remediation contractor and weekly briefings during project meetings. GEI was also responsible for preparing and submitting the results of the air monitoring activities in a final project air monitoring report.