The Second Street Subsite is one of seven subsites comprising the Hastings Groundwater Contamination Site. The subsite is a former Manufactured Gas Plant (MGP) property, which occupied one city block located at the eastern edge of the Hastings downtown shopping district. The MGP operated from the 1880s to 1930, when natural gas became available in the Hastings area. After abandonment by the MGP operator, the property was acquired by the City of Hastings, and various structures, including a building housing the Police Department, were constructed.
Contamination of the soils and groundwater resulted from historical waste disposal practices. The contamination includes benzene, polycyclic aromatic hydrocarbons and related organic compounds produced during the coal gasification process. The contaminated groundwater has migrated a distance of about one-half mile from the MGP property.
Current Site Status and Cleanup Actions to Date
- In 1996, EPA performed a soil-gas investigation to determine the locations of localized areas of soils contamination. After extensive field investigation efforts to determine the extent of groundwater contamination, EPA completed a Feasibility Study (FS) in 2002.
- A Record of Decision (ROD) for the ground water operable unit was completed by EPA in 2003. The selected remedy includes continuation of the ongoing cleanup activities initiated by EPA as Removal Actions. In addition, the selected remedy calls for treatment of the down-gradient ground water contaminant plume using two different technologies. The groundwater will be treated utilizing an in-situ bioremediation (PDF) (1.5M, 2 pp) process, by injection of chemicals known as oxygen release compound and by the use of conventional groundwater extraction and treatment (PDF) (526 K, 2 pp).
Current Funding Status
- EPA has spent approximately $2 million in performance of field investigations. This work included sampling of the soils, soil gas and groundwater and completion of the feasibility study for the groundwater operable unit.
- EPA has spent more than $2 million in performance of the first Removal Action (RA), which began operation in 1997 and more than $1 million in performance of the second Removal Action, which began operation in 2001.
- The cost estimate used by EPA to prepare the ROD for the ground water operable unit was $6.5 million. This amount is a present worth value based on discounting of costs to be incurred in future years.
- EPA obligated $200,000 in 2004 to fund the start of the RA, which included continuation of soil vapor extraction (SVE) (PDF) (80 K, 2 pp) and ground water treatment activities originally initiated as Removal Actions. These ongoing activities are mitigative in nature and additional actions are needed to control offsite migration of the groundwater contaminant plume.
- EPA anticipates $600,000 to start the next phase of remedial action, in-situ bioremediation utilizing chemical oxidation technology (PDF) (172 K, 2 pp). This process involves injection of oxygen release compounds directly into the contaminated plume using a series of wells.
- Subsequent to completion of the bioremediation phase, EPA anticipates installing the groundwater extraction and treatment system in 2007. This action is necessary to capture and treat the contaminant plume located down-gradient from the in-well aeration (IWA) treatment system. The capital costs are estimated at $400,000. The annual operation and maintenance costs are estimated to be approximately $50,000.
For more information on the projects at this site, please read the Hasting Groundwater Contamination Fact Sheet (PDF) (30 K, 10 pp) on the Region 7 Superfund Web site.
- EPA initiated treatment of the contaminated soils and groundwater at the source and utilized soil vapor extraction (SVE) (PDF) (80 K, 2 pp) and groundwater extraction and treatment in January 1997. These activities used Comprehensive Environmental Response, Compensation, and Liability Act (1980) (CERCLA) Removal Action Authority.
- The SVE system has removed more than 24 tons of contaminants from the soils. The groundwater treatment system has removed and treated more than 20 million gallons of contaminated groundwater at the subsite.
- EPA initiated treatment of the down-gradient groundwater contaminant plume in 2001, utilizing a recently developed technology known as in-well aeration (IWA). This activity was also funded using EPA's Removal Action Authority.
- The City of Hastings, Nebraska, has cooperated with the EPA investigations and performs the day-to-day operation of the treatment system located on the former Manufactured Gas Plant (MGP) property pursuant to an Administrative Order on Consent (OAC).