On behalf of the Kansas Department of Health and Environment, Burns & McDonnell began comprehensive investigation activities at a former manufactured gas plant (MGP) site in 1998, in accordance with the State Water Plan (SWP). Site characteristics and history include:
- Former MGP was active from 1886 to 1906
- The city of Wellington purchased the property in 1913
- The city uses the plant building for the Wellington School District
The objectives of the comprehensive investigation were:
- Fully delineate the extent of possible impacts to soil and groundwater
- Define locations of remaining below ground former structures
- Characterize site geology and hydrogeologic conditions
- Site assessment
- Site investigation
- Air sampling
- Feasibility study
Soil and groundwater at the site contained polynuclear aromatic hydrocarbons (PAHs), benzene, toluene, ethylbenzene and xylenes (BTEX), and metals at varying concentrations. Based on groundwater sampling conducted at the site, a dissolved phase plume was identified under the plant building, which is used by the school district.
To address the indoor air quality issue created by the presence of dissolved phase under the structure, indoor air sampling was initiated in 2001. Sampling consists of quarterly monitoring of the indoor air quality by placing Summa canisters at approximately 3 to 4 feet in height (normal breathing height for children) in four locations throughout the building. An orifice is attached to the Summa canisters to allow for a four-hour sample to be collected. A mechanical inspection of the building heating ventilation and cooling (HVAC) system was conducted by a Burns & McDonnell mechanical engineer. Modifications were made to the existing HVAC system to move the existing air intake and create a positive pressure inside the building, and reduce the potential for vapor migration into the building. Additionally, alternatives for vapor mitigation systems are being evaluated.