A framework for assessing risk reduction due to DNAPL mass removal from low permeability soils
- R. Allan Freeze Engineering, Inc., White Rock, British Columbia (Canada)
- Colorado State Univ., Fort Collins, CO (United States)
Many emerging remediation technologies are designed to remove contaminant mass from source zones at DNAPL sites in response to regulatory requirements. There is often concern in the regulated community as to whether mass removal actually reduces risk, or whether the small risk reductions achieved warrant the large costs incurred. This paper sets out a framework for quantifying the degree to which risk is reduced as mass is removed from shallow, saturated, low-permeability, dual-porosity, DNAPL source zones. Risk is defined in terms of meeting an alternate concentration level (ACL) at a compliance well in an aquifer underlying the source zone. The ACL is back-calculated from a carcinogenic health-risk characterization at a downstream water-supply well. Source-zone mass-removal efficiencies are heavily dependent on the distribution of mass between media (fractures, matrix) and phases (dissolved, sorbed, free product). Due to the uncertainties in currently-available technology performance data, the scope of the paper is limited to developing a framework for generic technologies rather than making risk-reduction calculations for specific technologies. Despite the qualitative nature of the exercise, results imply that very high mass-removal efficiencies are required to achieve significant long-term risk reduction with technology, applications of finite duration. 17 refs., 7 figs., 6 tabs.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- OSTI ID:
- 447161
- Report Number(s):
- ORNL/TM-13305; ON: DE97050722; TRN: 97:001173-0002
- Resource Relation:
- Other Information: PBD: Aug 1996; Related Information: Is Part Of In situ remediation of DNAPL compounds in low permeability media fate/transport, in situ control technologies, and risk reduction; PB: 318 p.
- Country of Publication:
- United States
- Language:
- English
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