Project Description

CASE STUDY: Chemically Oxygenated Granular Activated Carbon {COGAC™) Injection

This case study presents site information, remedial injection material, injection method and post injection results at a petroleum hydrocarbon underground storage tank (UST) release site in the state of Colorado. This was one of the first sites in which Remington utilized the standardized COGAC™ formulation for which we have long term groundwater data.

Site Information

In the treatment area, the groundwater occurred within a silty clay material common in the area and well known to present difficulties for in-situ remediation techniques. The depth to groundwater was relatively shallow at approximately 5 to 10 feet below ground surface (bgs). The shallow injection interval and smear zone media combined to make this site a potentially problematic site for remedial injection.

Remedial Material

One injection event of standardized COGAC™ was conducted over a 5- day period between October 28, 2013 and November 1, 2013. Between 100-gallons per point and 50-gallons per point of a 12% COGAC™ solution was injected into each of 73 injection points. A total of 8,800 gallons of the remedial material was injected during the event.

Remedial Injection Method

The remedial injection method used at the injection site utilized Direct Push Technology (DPT) and Remington’s auger/packer system. Given the shallow injection interval, our proprietary auger/packer system was utilized to focus the remedial material into the impacted smear zone. The injection grid was spaced on a 7.5-foot grid as allowed by above ground structures and below ground utilities and determined by the inferred plume map (attached). In this case, the injection interval of 5-10 feet was utilized as a single zone. Total cost for the project was less than $50,000.00.

COGAC™ Remedial Injection Results

As shown on the following graphs, dissolved phase benzene concentrations within the injection area, were reduced to below regulatory levels immediately after the injection event. Total petroleum hydrocarbon concentrations decreased as well, however, this was not a factor for regulatory considerations.

This site is significant as it was one of the early COGAC TM injection sites for which approximately 3-years of data are available for review. During that time, there was no rebound observed in any of the monitored constituents of concern (CoCs). Also significant, monitoring wells located outside of the injection area had dissolved phase benzene present in the groundwater. Dissolved phase benzene concentrations in these wells maintained historical levels and fluctuations with no discernable downward trend.

Historical Benzene Data Monitoring Wells Within Injection Area

Historical Benzene Data Monitoring Wells Outside of Injection Area