Groundwater Remediation Project for Chloroform Contamination

Site Background

This site has been in operation as a GMP-certified synthetic pharmaceutical plant since 1987.  In its early years, the plant temporarily used trichloromethane (chloroform) in its processes but this was discontinued after process adjustments. In 2012, trace amounts of trichloromethane were detected by the Ministry of Environment in on-site monitoring wells.

Concentrations were found to be gradually rising, and by 2018, they exceeded regulatory standards, leading to the site’s designation as a groundwater pollution control site and the establishment of a control area.

Pollution Status

Following a multi-phase investigation and evaluation, the source and spread of groundwater pollution were confirmed to be localized to trichloromethane contamination in the groundwater, concentrated around the underground wastewater treatment facility. Pollution extended to the base of the site’s first aquifer at an average depth of 13 meters (12-15 meters) below the surface. The wastewater facility is situated at the site’s downstream boundary, an area characterized by low-permeability strata. Contaminants leaked from early operations had persisted, binding to silt-clay particles and gradually diffusing, creating a long-term pollution source.

Remediation Approach

To prevent pollutant spread beyond the facility,  ApolloTech implemented an In Situ Chemical Oxidation  approach using alkaline-activated persulfate to treat groundwater contaminants without the risk of generating secondary pollution products. After a pilot test to establish the reagent injection radius and effectiveness, four full-scale injections were conducted. A multi-depth double-packer injection system was employed to deliver reagents precisely in high-concentration, low-permeability zones. Reagent ratios and volumes were adjusted based on updated contaminant concentration data, distribution, and baseline water quality after each phase. Groundwater contamination levels dropped significantly at the project start, and after the second injection, concentrations met remediation targets. The downstream boundary area concentrations remained consistently low, allowing for early validation and de-listing.

Award-Winning Research

The ApolloTech team developed a method for using detector tubes to quickly screen chloroform concentration levels in groundwater on-site. This innovation allowed for real-time adjustment of reagent ratios, injection volumes, depths, and pressures, enhancing remediation efficiency. This research was presented at the “2022 Soil and Groundwater Pollution Remediation” conference and received a merit award.