Alternatives for Managing the Nation's Complex Contaminated Groundwater Sites (2013) / Chapter Skim
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3 Remedial Objectives, Remedy Selection, and Site Closure
3 Remedial Objectives, Remedy Selection, and Site Closure
Pages 75-112
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From page 75... ...
. Many of these efforts appear to be in response to the slow pace of cleanup of contaminated groundwater; the inability of many technologies to meet drinking water-based cleanup goals in a reasonable period of time, particularly at sites with dense nonaqueous phase liquids (DNAPLs)
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From page 76... ...
This includes sustainability concepts that have become relevant to decision making regarding remedy selection and modification in the past few years. The topic of setting cleanup objectives has a long history and was a significant component of the debates in the 1980s during the passage of the Superfund Amendments and Reauthorization Act (SARA)
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From page 77... ...
, remedial alternative assessment (Feasibility Study) , remedy selection (Record of Decision)
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From page 78... ...
At most Superfund facilities with groundwater contamination, federal and state drinking water standards (such as maximum contaminant levels, MCLs, and non-zero maximum contaminant level goals) are established as ARARs and hence the groundwater cleanup goals.
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From page 79... ...
Balancing Criteria. On a case-by-case basis, the remedy selection criteria (particularly the balancing criteria) are "balanced in a risk management 2 DNAPL may migrate within the area of waste management.
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From page 80... ...
In some cases, the difference between the federal MCL and the state MCL is more than an order of magnitude. For example, the federal drinking water limit for cis-1,2-dichloroethene (cis-1,2-DCE)
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From page 81... ...
. An issue discussed in Chapter 7 but introduced here is that of the discount rate and its role in remedy selection in addressing one of the nine NPL criteria, namely cost effectiveness.
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From page 82... ...
Massachusetts 5 ppb 5 ppb 70 ppb n/a New Jersey 1 ppb 1 ppb 70 ppb n/a (state MCL) (state MCL)
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From page 83... ...
Drinking Water 2 ppb n/a State Code of http://www.state. (state MCL)
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From page 84... ...
That is, statements as explicit as "70% reduction in concentration" or "removal of mobile DNAPL" are not provided as definitions of "maximum extent practicable." The main statutory reference to the term "maximum extent practicable" is found in CERCLA in reference to practicability during remedy selection, where practi cability reflects a balancing of the nine criteria specified in the NCP (EPA, 2009a, p. 4, footnote 9)
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From page 85... ...
. Thus, as long as the remedy is chosen in accordance with the NCP and is performing in accordance with reasonable environmental engineering practices, that is the end of decision making with respect to what is practicable for remedy selection.
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From page 86... ...
are imposed. According to the NCP, institutional controls are supposed to supplement, not substitute for, active remediation "unless such active measures are determined not to be practicable, based on the balancing of trade-offs among alternatives that is conducted during remedy selection" [40 CFR § 300.430(a)
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From page 87... ...
. EPA's RCRA guidance specifies that cleanup levels be set at federal drinking water standards (where they exist)
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From page 88... ...
In the Committee's opinion, this may be a major reason that federal agencies prefer CERCLA, where they will maintain lead agency status, even though RCRA provides greater flexibility in establishing remedial objectives and points of compliance. Federal facilities that are being transferred to non-federal ownership are subject to additional oversight under CERCLA Section 120(h)
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From page 89... ...
And third, at many complex sites attaining drinking water standards throughout the contaminated groundwater zone is difficult and unlikely for many decades, which can complicate the latter stages of remediation. Interim and Emergency Responses At most complex sites, actual cleanup activity begins long before the selection of a final remedy.
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From page 90... ...
. At the MEW site responsible parties removed contaminated soil, conducted soil vapor extraction, and installed localized groundwater extraction and treatment systems long before the development of a regional remediation strategy (EPA, 2009b)
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From page 91... ...
to drinking water standards quickly. Because the history of groundwater cleanup is still relatively recent, in that few sites with remedies have been
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From page 92... ...
The remedial alternatives should be reviewed to determine the timeframe, the cost, and the practicality of reducing the concentrations in groundwater to drinking water standards. This requires the transparent exchange of technical and cost information between regulators and responsible parties.
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From page 93... ...
In the Committee's experience, EPA and state drinking water standards usually drive groundwater cleanup rather than the results of site-specific risk assessment. This can lead to responsible parties, regulators, and the public having an incomplete understanding of risk-related issues, including the plausibility of the scenarios that are driving decision making, the likely site risks at the present and in the future, and site risks reduced to date.
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From page 94... ...
. This is not an uncommon occurrence at complex sites, where contaminant concentrations may reach an asymptote beyond which there is very little, if any, further decline in concentration despite continued operation of an active remedy.
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From page 95... ...
. Despite the existence of these risks, few remedy selection decisions consider them in a quantitative way (Leigh and Hoskin, 2000)
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From page 96... ...
Reasons for uncertainty may include a lack of experimental data in the dose range of interest or lack of understanding of the mode of action for carcinogenesis. In the case of groundwater contamination, an important source of uncertainty in risk assessment is often the choice of use scenarios for contaminated groundwater.
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From page 97... ...
Table 3-2 presents some sources of uncertainty and variability in risk assessment for contaminated groundwater. Additional Strategies for Goal Setting Many strategies have been developed and accepted by regulators to acknowledge site complexity and inherent technical and cost barriers to achieving drinking water standards, yet provide a path forward that reduces risk and retains the ability to determine when unrestricted use is appropriate.
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From page 98... ...
. Eighty-five TI waivers have been issued for ground 8 "Applicable requirements" are those "cleanup standards, standards of control, and other substantive environmental requirements, criteria, or limitations promulgated under federal environmental or state environmental or facility sitting laws that specifically address a hazardous substance, pollutant, contaminant, remedial action, location, or other circumstance found at a CERCLA site." 40 C.F.R.
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From page 99... ...
Alternate Concentration Limits Alternate concentration limits (ACLs) , which apply at CERCLA and RCRA sites, allow the use of a remediation goal in groundwater that is protective of surface water into which contaminated groundwater discharges, rather than the drinking water standard.
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From page 100... ...
The ESTCP (2011) report on alternative strategies for site management makes it clear that alternative remedial objectives are not used in many situations where they might apply, despite their attractiveness for dealing with complex sites.
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From page 101... ...
Timeframes beyond 20 years were felt to reduce the likelihood of holding parties accountable for remedial performance. Despite these initiatives, there is still widespread reluctance by federal and state regulatory agencies to accept the concept of alternative remedial objectives.
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From page 102... ...
, impacts on various environmental media and natural resources, and community involvement can be assessed under existing remedy selection schemes. However, ethical and equity considerations, indirect economic costs and benefits, and employment and capital gain (among others)
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From page 103... ...
In the hazardous waste arena, the leader in sustainability is the Sustainable Remediation Forum (or SURF, http://www. sustainableremediation.org)
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From page 104... ...
At a Naval Air Station Superfund facility in Weymouth, Massachusetts, EPA modified an excavation remedy to allow reuse of the soil as a subgrade fill layer rather than disposing of the soil offsite, which "significantly reduced energy con sumption associated with truck trips for off-site disposal and importing common fill and allowed for the beneficial reuse of the excavated materials in a manner which is protective of human health and the environment." Emissions of regulated air pollutants were also reduced (EPA, 2010d)
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From page 105... ...
. Legal Basis for Considering Sustainability As mentioned previously, sustainability criteria are not included explicitly in CERCLA or RCRA guidance on remedy selection or modification (e.g., the feasibility study guidance, EPA, 1988b)
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From page 106... ...
Of course, potentially responsible parties including the military may decide voluntarily to implement a remedy that goes beyond what might be selected by application of the nine remedy selection factors, based on a general good neighbor policy or adoption of a policy such as sustainable development. There is greater incentive to use sustainability factors in remedy selection when the costs of the remedial alternatives are similar.
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From page 107... ...
However, in the absence of statutory changes, remedy selection at private sites regulated under CERCLA cannot consider the social factors, and may not include the other economic factors, that fall under the definition of sustainability. At federal facility sites, the federal government can choose, as a matter of policy, to embrace sustainability concepts more comprehensively.
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From page 108... ...
2010. Draft Underground Storage Tank Low Threat Site Closure Policy.
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From page 109... ...
1996a. The Role of Cost in the Superfund Remedy Selection Process.
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From page 110... ...
2011d. Groundwater Road Map Recommended Process for Restoring Contaminated Groundwater at Superfund Sites.
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From page 111... ...
for risk as sessment at hazardous waste sites.
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