Closure and Johnston Atoll Chemical Agent Disposal System (2002)

The closure activities at JACADS consist of decontamination and removal of process equipment and building structures and some soil removal and disposal. Although no requirement for groundwater treatment is anticipated at Johnston Island, other CSDP disposal sites might require groundwater treatment, which would affect the closure process and the ultimate postclosure monitoring at those sites.

The actual JACADS closure activities should be defined in a detailed closure work plan. The work plan is separate from the closure plan as it contains a great amount of detail about each specific activity that is to be conducted during closure. The plan will be agreed to by all parties involved and approved by EPA Region IX, the regulatory authority with oversight responsibility for JACADS. In this sense, the work plan can be considered a legal document that contains the essential postclosure activities and the postclosure report and certification for the JACADS site. In addition, the closure work plan may also include certain additional elements that the Army plans for closures of other sites where circumstances are different.

A draft RCRA facility assessment (RFA) for JACADS was submitted to EPA for approval on December 12, 2000. This RFA, which forms the basis for developing a closure work plan and a set of postclosure activities, suggested that 19 areas of interest (AOIs) require no further action and that 52 solid waste management units (SWMUs) and 24 AOIs are potentially contaminated and require further action (investigation). These AOIs and SWMUs range in size from about 100,000 square feet to less than 100 square feet. Typically, in a commercial facility closure, they would be combined into as few units as possible for the execution of the closure plan. Based on the information in the RFA and subsequent data from any further field investigations, a closure work plan will be developed that specifies closure activities as well as any postclosure activities.

Demolition activities at JACADS present a particular set of issues, as not all buildings and surfaces are expected to be contaminated with agent or other toxic compounds. Sampling activities for demolition waste consists of confirming whether or not the wastes are contaminated and ensuring that adequate data are compiled to support the classification and disposal methods to be used. Each pile sampled for disposal purposes must be documented as coming from the location specified in the sampling plan. This will ensure that the waste from a particular pile will not contain unknown or unanticipated contaminants that would prevent disposal. It is vital that the final closure report submitted to EPA contain a full and detailed account of what was done, how it was done, and the ultimate disposition of all demolition wastes.

The sampling procedures that are used during postclosure activities depend upon the identified areas of concern, specific contaminants in all media, and the required end states (i.e., cleanup levels to be attained). Sampling methods must be scientifically defensible and statistically sound. For example, polychlorinated biphenyl (PCB) sampling protocols for soil disposal specify the number of samples, the frequency, the compositing guidelines, the sample preservation methods, etc. (Keith, 1988, 1990). Although JACADS has chemicals other than PCBs, applying the principles behind the development of the PCB guidelines provides a very useful approach that is widely accepted by EPA. Sampling methods for postclosure may be similar to those for monitoring closure activities. For JACADS, these methods must address the specific contaminants identified in the RFA and in the closure plan: metals, volatile organic compounds, semivolatile organic compounds, agents, and agent degradation products. The philosophy behind postclosure sampling should be to develop and implement procedures that clearly demonstrate that specified end states have been met and that there are no further risks to people or the environment.

Sample analyses should be performed in a laboratory certified for the necessary procedures, and they must be able to meet detection limits in the expected media and chemical mixtures. Some analyses are specified by existing EPA protocols, but this is not the case for agent and agent degradation products. Both the closure plan and the postclosure plan should precisely define the protocols to be used for these classes of compounds, including precision and accuracy for expected contaminants.

The methodology used for the area survey should define procedures to ensure that adequate samples are taken for each area designated for closure activities in the RFA and work plan. Closure activities could include soil removal, demolition, soil remediation, sediment remediation, and groundwater or surface water treatment. An example of a procedure often accepted by EPA is to assess an excavation for cleanliness by analyzing samples taken from the sides and bottom of the excavation. In some circumstances, these samples may be composited, but the technique is unique to each site and to each AOI or SWMU. The postclosure sampling plan should strive to minimize the number of samples needed while demonstrating that the agreed-on cleanup goals have been met.

If required, pump-and-treat groundwater remediation and/ or in situ bioremediation are options, but unlike with soil excavation, it may take years for contaminant concentrations to reach the agreed end point. The postclosure part of the closeout activities plan should contain a well-defined exit strategy for any necessary postclosure remediation, based on a sampling methodology that defines progress and determines when the end point is reached.

Careful and thorough records documenting closure activities should be kept. These records might include:

• photographic data, including video recordings where appropriate

• thorough and complete field notes that fully describe the samples taken, where taken, chain-of-custody procedures, sample preservation procedures, holding times, and similar items

• documentation showing that the personnel performing the work were qualified and certified when appropriate

• actual postclosure sampling activities with planned activities for AOIs, SWMUs, etc. in order to establish whether all required activities were accomplished

The postclosure survey report should fully and completely document all activities and all results (data), and it should certify that the closure has been done in compliance with the work plan and all applicable laws and regulations. A professional engineer licensed in the state where the closure was done must attest to the report. (In the case of JACADS, the state is California, where the EPA Region IX office is located.) Appendix E provides two sample tables of contents from industrial RCRA closure survey reports accepted by EPA; they can be used as a guide to the contents of the final and interim reports required. Box E-1 shows the table of contents for a final facility RFI postclosure report. Box E-2 shows the table of contents for an interim remedial measures report, used to obtain EPA conditional approval for the cleanup of specific areas prior to final facility closeout.

As noted earlier, long-term monitoring requirements for remediated sites most commonly involve groundwater treatment and/or ongoing soil treatment. The monitoring requirements will be specific to each site and to the chemicals treated. For JACADS closure, because the only groundwater present on Johnston Island is that beneath the original 6 percent of the island that is naturally occurring, and since the facility is not on this land, no groundwater monitoring is planned by the Army. Postclosure monitoring plans at each facility should be developed in a manner that will demonstrate what is to be monitored and when the remediation is complete.