Remediation Status: Site closed

Why the technology was selected:
The owner was in a hurry to construct on the site.

Date implemented:
July 2005

Final remediation design:
There is a collection pipe under the half of the building that was built on the former dry cleaner's location. It leads to one end of the building and vents above the roof. A blower unit was installed in the vent piping but was later bypassed to convert the system to passive operation. There is a cleanout access in the piping at ground level.

Results to date:
The system is still operating passively. It has had little to no effect on the contaminants underground. Indoor air test results are inconclusive as to the effect of venting because the system was installed during construction so there are no unvented samples for comparison but indoor air rarely showed traces of dry cleaning chemicals. The subslab effluent results indicated consistentlevels of tetrachloroethylene higher than the Tier I non-residential indoor air critera of less than 0.00909 mg/Kg/cubic meter. Trichloroethylene and vinyl chloride occasionally exceeded also.

Next Steps:
The site is closed based on a Tier 2 Missouri Risk-Based Corrective Action Risk Assessment. Indoor Air was not part of the Tier 2 assessment as it was considered an incomplete pathway due to the mitigation.