Site closure

U.S. EPA, Cost of In Situ Treatment of Fuel Oxygenate, Site Closure and the Total Cost of Cleanup, Conference on Remediation, National Ground Water Association, New Orleans, November 13-14, 2003. 

Monitoring remedial progress requires monitoring of both groundwater and aquifer media samples for compounds of concern and other indicator parameters. Typically, groundwater samples should be collected and analyzed monthly, or quarterly at a minimum. More frequent sampling is not usually justified because groundwater flow is relatively slow and biochemical reactions in the subsurface are typically slow compared with laboratory reactions. Confirmatory soil samples are routinely collected, prior to site closure, to demonstrate that cleanup objectives have been achieved. 

Since the remaining residual hydrocarbons were localized, and had no impact on groundwater quality, a risk-based closure approach was taken, and subsequently approved for site closure. This case history is typical of many UST sites in that full removal of hydrocarbons below regulatory levels is not achievable for a variety of reasons. This will be further discussed in Chapter 13 (Site Closure). 

Natural attenuation was favorably received and approved as an appropriate remedial alternative for these two sites. Periodic gauging and monitoring of key parameters will continue for a minimum period of 2 to 3 years to demonstrate continued stability and/or decline in dissolved BTEX prior to site closure. 

Considering the remote location of JACADS, the problems involved in coordinating multiple contractors on the island, and the time and cost penalties inherent in educating another contractor, continuation of the operating contract (with appropriate changes to accommodate closure) appears to be justified. With the benefit of the lessons learned at JACADS, the use of another operations contractor to perform site closure at continental U.S. sites should be considered. The best strategy to employ will depend on site-specific considerations. 

Technology expected to treat contaminants more rapidly than other in situ technologies, leading to more rapid site closure and reduction in liability. 

Quickly remediates contaminants, allowing for rapid site closure. 

In general, biodegradation technologies may have difficulty meeting site closure requirements. 

At a brownfield site in Illinois, the biopile process was used with air sparging to treat soils contaminated with petroleum hydrocarbons and by-products of asphalt production. Treatment at the 13- to 15-acre site occurred for one year, and site closure was achieved as a result of the process. The project cost was approximately 100,000, which was significantly less than the estimated cost of landfilling the contaminated soil (D21948R, pp. 3, 5). 

The ORC system is designed to treat a plume with a peak BTEX concentration of 25 ppm and close the site in 1 year. The values for the air sparging system were derived independently by the site consultant and site closure is expected in 3 years (D138231). 

According to the vendor, the full-scale remediation of contaminated soil at the McKin Superfund site in Gray, Maine, was 2,900,000. This figure included the costs for salaries and wages, rental, supplies, subcontractors, fuel, and other professional services. It did not include the expenses associated with mobilization, site characterization, pilot-scale treatability testing, waste material disposal, site closure, or demobilization (D14110W, p. 64). 

---