As indicated earlier, another limitation with regard to operational ranges is that DERP funding may not be used to fund cleanup at these sites. That limitation can be problematic in that some of the largest locations where CWM is known to be buried are on operational ranges (such as Redstone Arsenal).
Emergency response to a situation where a CWM or potential CWM is identified either on or off an installation or at an established BRAC or FUDS is generally “a situation in which there is an imminent and substantial threat to human health or the environment and which requires immediate and expeditious action to eliminate the threat” (EPA, 2010). As indicated previously, the RCRA Munitions Rule provides an exemption from permitting requirements for emergency response. However, the preamble to the final rule indicates that a responder should consult with an applicable state regulator if there is time.
Once an emergency is over, however, depending on the potential for additional munition items (including CWM) and location of the site, the site may become a FUDS. The Spring Valley site in Washington, D.C., was initiated as an emergency response in 1993 and has become one of the longest-active FUDS in the nation.
TYPES OF REMEDIES
Two types of remedies may be considered for CWM-containing MRSs. CWMs may be left in place with institutional “land-use controls” (LUCs) and continued monitoring, or they may be actively removed and destroyed. In addition, when CWMs are actively removed and destroyed, RCWM destruction may take place onsite (close to the point of extraction), or they may be transported to a specifed offsite location for destruction. The types of remedies for CWM-containing MRS are discussed below.
Leave in Place with Institutional (Land-Use) Controls
Buried CWM can be left in place with LUCs to prevent unauthorized access and with deed restrictions to prevent future uses that are incompatible with buried munitions. Most often, this type of remedy is accompanied by emplacement of an engineered cap and continued monitoring of media (such as groundwater) for an indefinite period to detect migration of contamination or fuctuations in contaminant concentrations. If unexpected migration or contaminant fuc-tuation is detected, additional remedies may be considered. Sometimes, this type of remedy is accompanied by active treatment, such as pumping and treating of contaminated groundwater.
The leave-in-place remedy is commonly used in both RCRA and CERCLA cleanups. It is used when leaving contamination in place can be shown to be acceptable from a risk perspective and when removal of contamination would be technically impracticable or financially prohibitive. It is also used when the physical removal of contamination and later treatment can be shown to pose a health or environmental risk. That was the case at Old O-Field at Aberdeen Proving Ground, Maryland, where, among other concerns, reactivity of energetic materials was thought to pose an unacceptable risk to workers. CWM at Old O-Field was consolidated and buried on the site with a specially designed cap and indefinite monitoring of air and groundwater. As an NPL site, it is reviewed every 5 years as required by the National Oil and Hazardous Substances Pollution Contingency Plan.
The leave-in-place remedy is typically far less expensive than removal, but there is a continuing cost and liability and, of course, long-term restrictions on land use and associated loss of economic beneft that may be associated with that long-term use. Implicit in this remedy is the need to maintain ownership and control of the affected land area. For that reason, the remedy is limited to active installations. It may also be used at BRAC sites or at non-BRAC closures, such as Rocky Mountain Arsenal, where a federal land manager retains control over future land use. Although the remedy theoretically could be used at FUDS, it is unlikely to be acceptable to landowners, adjacent landowners, and state and local government.
Active Removal and RCWM Destruction
In accordance with DOD’s interim guidancefor CWM responses (U.S. Army, 2009e), “Munitions with an unknown liquid fll that are determined to be CWM and any CWM recovered during a CWM response will normally be treated (destroyed) on site using approved contained destruction technology.” With the remove-and-destroy approach, buried CWM is eliminated permanently and, assuming that the remainder of the MRS site (including contaminated soil) is remediated to accepted standards, the land may be returned to beneficial use.
Removal and destruction would entail location of the CWM, removal from the burial site, and then contained destruction. Although it would be most efficient, as indicated in an earlier National Research Council report on international technologies (NRC, 2006), to move the RCWM directly from the burial site to the destruction device, interim storage for some period is sometimes required. Most RCWM can be safely stored in an IHF, as described previously. Destruction of the RCMW with a contained destruction technology would involve the EDS or one of the EDTs, as described previously. The IHF and EDS or EDTs could be approved as TUs with the limitation that they would not be able to be operated for longer than 2 years.