Diesel Dual Phase Vacuum Extraction  

UST DIESEL RELEASE PROBLEM

Remtech was engaged by a major bus terminal to remediate an estimated 7,000 gallon diesel fuel release from a twenty thousand gallon (20,000) underground storage tank. The 0.33-acre plume of fuel was located with 33 monitoring wells under a bus wash/service building and parking lot. Remtech secured reimbursement from the State’s Leaking Underground Trust Fund for this project.

UST DIESEL RELEASE REMEDIATION SOLUTION

Seventeen (17) recovery wells were installed following removal of the leaking UST. A Remtech dual-phase vacuum extraction system was installed that consisted of a rotary claw blower, knockout tank, oil/water separator (OWS), multimedia pre-filters and activated carbon post-filters. This project was complicated by tight clay soils (conductivity of 6.3 x 10-6 cm/sec) and iron bacteria floc that created a biofilm that clogged filtration systems.

Dissolved air floatation (DAF) and calcium chloride coagulation/ flocculation were added to the oversized OWS to assist with the separation of fuel from the bio-floc.  For every gallon of fuel recovered, 1/3rd gallon of fuel entrained iron bacteria sludge had to be removed. Sludge entrained fuel was separated by placing solids in sludge thickening tanks with extended retention times. This was one of the worst iron bacteria fowling problems encountered in the State of Georgia.

IIron bacteria buildup in the wells required well rehabilitation with surge blocks, jetting, hydrochloric acid, calcium hypochlorite, hydrogen peroxide, citric acid, glycolic acid, and HC-2000 injection. 48.44% of the free product was removed during the first four (4) years of operation of the dual phase extraction system.

To accelerate the completion of this remediation project, approval was received from the State to inject Remtech's proprietary HC-2000 bioremediation accelerator and desorption agent.  92.63% of the remaining free product was removed with seven (7) injections of HC-2000 during the final year of the treatment program. The small quantity of free product remaining was determined to be immobile, stable, with no impacted downstream receptors.

An estimated 2,300 gallons of fuel were recovered over a five year period (not including bioremediated fractions of free product). This project was completed as a low risk site and a No Further Action Letter was received from the State UST Program.

UST DIESEL RELEASE REMEDIATION COST/BENEFITS

Project costs were completed for approximately $159/cy even with the unusual elevated iron bacteria biomass which accounted for over 30% of project costs. The client was reimbursed for this project by the State GUST Fund.