Fractured Rock Sites –Challenges and Significance for the Superfund Program

EPA Fractured Rock Workshop

John PrinceEPA Region 2 Remedy Selection/Design and Construction ManagerJanuary 14, 2013

Challenges

• Fractured rock much more difficult to characterize than unconsolidated aquifers

• Investigative approaches can be time consuming and costly

• Matrix diffusion causes retardation of plume movement BUT can result in large volumes of mass in the rock matrix

• Aquifer restoration is a challenging goal for many fractured rock sites

Significance

• Priority science need in Region 2 due to the large number of contaminated fractured rock sites in the region’s Superfund and RCRA programs

• Budget limitations/few shortcuts

• Many older sites with matrix diffusion may not achieve RAOs

Changes in Superfund?

Nothing has Changed:

"EPA expects to return usable ground waters to their beneficial uses wherever practicable, within a time frame that is reasonable given the particular circumstances of the site. When restoration of ground water to beneficial uses is not practicable, EPA expects to prevent further migration of the plume, prevent exposure to the contaminated ground water, and evaluate further risk reduction" (40 CFR 300.430(a)(1)(iii)(F)).

TI Waiver?

What it is not:

Looking Forward

• Implement investigative techniques that more accurately characterize the site

• Involve technical support staff

• Optimize old sites

• Strategies for new sites:• RI/FS SOW needs to include fractured rock

investigative techniques • Feasibility Study needs to:

• Consider “realistic” RAOs - mass reduction or reduction of flux from source area

• Evaluate technologies that address mass in the rock matrix

• If TI Waiver for part of site, remedial alternatives to restore/protect remainder of the site

Questions?