The Ramp Creek Site is located in western Heath in Licking County, Ohio. The site consists of a 350-acre ground water plume of petroleum hydrocarbons and five surface impoundments. The source of the ground water contamination is an old refinery, which is now a bulk gasoline terminal and pipeline transfer station owned by Marathon-Ashland. The refinery was originally built by Pure Oil Co. during the 1920s.
In 1970, petroleum began seeping into Ramp Creek. In 1973, Ashland installed a recovery well on its property. From 1975-81, U.S. EPA administered a clean-up near Ramp Creek and recovered approximately 400,000 gallons of petroleum. In 1989, the City of Heath complained to Ohio EPA that oil seeping into its sanitary sewer was adversely affecting its waste water treatment plant.
In 1990, the Ohio EPA filed a complaint against Ashland and Union Oil Co. of California (Unocal) in the Licking County Court of Common Pleas. In 1991, a Consent Order for Preliminary Injunction was entered in the court, signed by Ashland, Unocal and Ohio EPA. Ashland/Unocal agreed to characterize the nature and extent of the contamination, calculate the human health and environmental risks and evaluate clean-up options in a feasibility study. This work was completed in 1998.
On April 23, 1999, Ohio EPA public noticed its preferred plans for the impoundment area and ground water contamination and on Oct. 25, 1999, issued its decision documents. On Dec. 1, 1999, a consent order was entered into the Licking County Court of Common Pleas in which Ashland/Unocal agreed to design and implement remedial actions in accordance with Ohio EPA’s Preferred Plans and Decision Documents.
In 2005, Unocal and Chevron Corporation merged, and Chevron is now acting as the responsible party.
Remediation of the Impoundment Area: The impoundments were used for wastewater treatment, oil-water separation, oil recovery, storm water management and as a disposal area for tank bottom waste, caustic waste, waste lime and debris. The impoundments consisted of several feet of bottom sludge and a relatively thin layer of floating sludge. In 1993, Ashland/Unocal skimmed off most of the floating sludge. In 2000-2001, Ashland/Unocal stabilized the bottom sludge in-situ by injecting binding reagents. The impoundment area was capped with 2 feet of clay soil, 6 inches of top soil and planted with grass. Ohio EPA approved the completion of the remedial action construction on Jan. 8, 2001. The impoundment area is inspected quarterly and the integrity of the stabilized sludge remains good.
Remediation of the Ground Water: The contamination consists of a combination of “free-phase” hydrocarbons and dissolved benzene, ethylbenzene, toluene and xylenes (BTEX). Ground water is being cleaned up by using a combination of vacuum enhanced recovery (VER), free-phase removal, bioventing and monitored natural attenuation. Ohio EPA approved the completion of the construction of the remediation system on Dec. 3, 2002. Ashland and Chevron have expanded the VER system and are conducting enhanced bioremediation technology pilot studies.
As of the end of 2008, a total of 127,059 gallons of liquid hydrocarbons have been recovered from the vadose zone. Recent core samples have demonstrated that the VER system is reducing the thickness of the hydrocarbons, and ground water data indicates that BTEX concentrations have declined. The monitored natural attenuation area was evaluated in 2008, but it is too early in the process for Ohio EPA to determine the effectiveness of natural attenuation. Indirect evidence suggests natural attenuation is occurring in accordance with predictions.
Photograph 1: Site before clean-up activities.
Photograph 2: Site after clean-up activities.
Photograph 3: Installation of vacuum extraction/bioventing system, Sept. 26, 2003.
Photograph 4: View of global oxidizer, Sept. 26, 2003.
Photograph 5: Looking south, impoundment area as it looks today.
Summary date: January 2009