D&G Sunoco

  
Richmond, Kentucky  
SITE ADDRESS: 635 Big Hill Avenue
 

Richmond, KY 40476
   
   
CONTACT INFO: Dale Croucher
  Greg Moody
  859/623-9810
   
PROJECT COST: $850,000.00
The former D&G Sunoco site was operated as a service station from 1960 to 1988. The site had two 8,000 gallon, one 4,000 gallon, three 2,000 gallon, and one 1,000 gallon underground storage tanks (USTs), all containing gasoline, removed from the site. Following an initial investigation by others, Mr. Lloyd (currently of Alpha-Omega Environmental Management) continued the site investigation and subsequent corrective action. Both soil and groundwater was impacted with one monitoring well briefly containing free product. Ten groundwater monitoring wells were eventually installed on- and off-site to monitor contaminant concentrations and flow conditions.

Following tank removal, the two subsequent pits were overexcavated and soil and groundwater samples collected. Analyses indicated that both soil and groundwater was impacted beyond the property boundary. Since the contaminants had migrated below Big Hill Avenue (US 25), further excavation was not feasible. Geologically, the site consisted of silty clay down to approximately 12 feet where a weathered shale and limestone layer was encountered. A more competent limestone was encountered at approximately 15 feet with numerous large floats rising as much as six feet.

This complex geology presented quite a challenge in capturing and treating gasoline contaminants (BTEX) that were as high as 9 mg/L. An in-situ flush and treat remedial design was implemented that consisted of collecting groundwater at the downgradient property boundary then pumping through a 2,000 lb. granular activated carbon (GAC) unit. The discharge from the GAC unit was then mixed with nutrients to promote bioremediation and injected upgradient. This closed loop system was the first bioremediation UST corrective action plan to be approved by the Kentucky Division of Waste Management.

As the contaminant concentrations continued to decrease, the nutrient injection was halted in favor of more cost-effective techniques to address the remaining residual such as dual phase extraction (DPE) and monitored natural attenuation (MNA).