Alternatives for Managing the Nation's Complex Contaminated Groundwater Sites (2013) / Chapter Skim
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1 Introduction
1 Introduction
Pages 13-36
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From page 13... ...
Over the past 30 years, some progress in meeting mitigation and remediation goals at hazardous waste sites has been achieved. For example, of the 1,723 sites ever listed on the National Priorities List (NPL)
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From page 14... ...
Remedy in place means that a remedial strategy has been implemented and is in the performance assessment stage of the site's life cycle, while response complete means that remedial actions have been completed, 1 "Contamination remaining in place," as used in this report, is consistent with the interagency definition of hazardous substances, pollutants, or contaminants remaining at the site above levels that allow for unlimited use and unrestricted exposure (UU/UE)
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From page 15... ...
The central theme of this report is how the nation will deal with the complex hazardous waste sites where contamination remains in place at levels above those allowing for unlimited use and unrestricted exposure. REGULATORY RESPONSE TO GROUNDWATER CONTAMINATION The federal regulatory regime for responding to groundwater contamination consists of several key statutes and regulations enforced primarily by the EPA's Office of Solid Waste and Emergency Response (see Box 1-2 for an overview of the major U.S.
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The simplest geology is uniform media, like well-sorted sand (called homogeneous) , while more complex heterogeneous geology includes such varied media as poorly sorted sand with lenses of silt and clay.
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From page 17... ...
Complexity is also directly tied to the contaminants present at hazardous waste sites, which can vary widely and include organics, metals, explosives, and radionuclides. Some of the most challenging to remediate are dense nonaqueous phase liquids (DNAPLs)
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RCRA Corrective Action: RCRA is the primary federal statute regulating how wastes (solid and hazardous wastes) must be managed at facilities that treat, store, or dispose of hazardous wastes to avoid potential threats to human health and the environment.
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Relevant and Ap propriate Requirements are any Federal or duly promulgated state standard, requirement, criterion, or limitation under any other federal environmental law that addresses problems or situations similar to the conditions at a site and that is "well suited" to a site. MCLs promulgated under the Safe Drinking Water Act are considered to be ARARs for sites regulated under CERCLA because of the potential for people to ingest the groundwater derived from a contaminated aquifer.
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From page 20... ...
As more remediation began, it became clear that reaching drinking water standards such as maximum contaminant levels (MCLs) , which were the applicable or relevant and appropriate requirements (ARARs)
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Other regulatory programs provide similar remedial guidance for active sites, including those with underground storage tanks. The Departments of Energy and Defense have developed their own processes that mirror the remedial process found within CERCLA, but using different terminology, while the states implement the federal laws over which they have primacy as well as state programs that encompass additional contaminated sites.
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From page 22... ...
Once these are in place, remedial action objectives are set, and then remedial alternatives are evaluated and a remedy selected that will meet those objectives within a "reasonable"4 time 4 The definition of "reasonable" has been debated for many years at EPA and in state regulatory agencies. There are no statutory or regulatory definitions of this term in the context of soil and groundwater cleanup.
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From page 23... ...
For example, institutional controls like deed restrictions are often necessary for long-term management at sites where physical or hydraulic containment of the contamination is a component of the final solution. Whether long-term management sites will ever attain contamination levels below those allowing for unlimited use and unrestricted exposure is often uncertain; at many sites, perpetual management may be necessary, particularly those with recalcitrant contaminants.
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From page 24... ...
Indeed, many sites closed under the UST program have residual contamination left in place, some at levels above those allowing for unlimited use and unrestricted exposure. In the case of Superfund, an NPL delisting does not necessarily have to be based on the attainment of MCLs if the human health and environmental risk of the remaining contamination is minimal, groundwater migration is controlled, and remediation is technically impracticable (see Chapter 2)
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From page 25... ...
. Each of the NRC studies has, in one form or another, recognized that in almost all cases, complete restoration of contaminated groundwater is difficult, and in a substantial fraction of contaminated sites, not likely to be achieved in less than 100 years.
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provided a comprehensive review of groundwater and soil remediation technologies, focusing on three classes of contaminants that have proven very difficult to treat once released to the subsurface: metals, radionu clides, and DNAPLs, such as chlorinated solvents. The report concluded that "removing all sources of groundwater contamination, particularly DNAPLs, will be technically impracticable at many Department of Energy sites, and long-term containment systems will be necessary for these sites." Natural Attenuation for Groundwater Remediation (NRC, 2000)
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From page 27... ...
; it does not imply removal or destruction of all contaminants. Cleanup is the restoration of the affected site to a condition allowing for UU/UE which generally implies meeting drinking water standards in the case of contaminated groundwater.
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The y axis could be any decision variable used to measure the remedial objective (e.g., the contaminant concentration at a point of compliance)
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TCE and other contaminants are thought to be migrating vertically and horizontally from the source areas, affecting groundwater downgradient of the base including the potable water supply to the City of Anniston, Alabama. The interim Record of Decision called for a groundwater extraction and treatment system, which has resulted in the removal of TCE in extracted water to levels below drinking water standards.
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From page 30... ...
4. The Future of Treatment Technologies he intractable nature of subsurface contamination suggests the need T to discourage future contaminant releases, encourage the use of innova tive and multiple technologies, modify remedies when new information becomes available, and clean up sites sustainably.
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From page 31... ...
, the military, the Department of Energy, and state remediation programs. For all programs, the Committee sought information on the total number of sites, the costs expended to date and to clean up remaining sites, and the number of sites affecting a drinking water supply.
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From page 32... ...
It should be noted that the report does not comprehensively discuss the need to discourage future contaminant releases, as significant progress has been made in this area. That is, it is now so expensive to manage contaminated sites that potentially responsible parties will go to great lengths to avoid causing groundwater contamination.
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From page 33... ...
." PRPs would pay ELMO to assume liability and site management, and the payment would cover expected damages and management costs for as long as the contamination remains above levels allowing for unlimited use and unrestricted exposure. The Committee could not agree on the details of such a proposed entity, but all members agreed that future consideration of such an organization could potentially provide a number of advantages to all parties, especially in the context of long-term management of sites.
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From page 34... ...
2012. Manual, Defense Environmental Restoration Program No.
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From page 35... ...
2011. Policy for Refocusing the Air Force Environmental Restoration Program.
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