No abstract

No abstract

No abstract

No abstract

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden to Department of Defense, Washington Headquarters Services, Directorate for Information SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITORS ACRONYM(S) ESTCP SPONSOR/MONITOR'S REPORT NUMBER(S)Environmental Security Technology Certification Program 901 North Stuart Street, Suite 303 Arlington, VA 22203 DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES ABSTRACTThe primary objective of this report is to describe the results of the last round of monitoring conducted in July 2004, their relationship to the results of pervious rounds, and their implications for the longevity and hydraulic performance of the permeable reactive barrier (PRB). ii ACKNOWLEDGEMENTS This study was funded by the Department of Defense's (DoD) Environmental Security Technologies Certification Program (ESTCP) through the Naval Facilities Engineering Service Center (NFESC). Battelle, under contract to NFESC conducted the laboratory and field investigation associated with the study. The authors also acknowledge the support provided by Mary Parker from Navy's Southern Division and by several staff from Tetra-Tech EMI, the on-site Navy contractor, who provided additional field support. SUBJECT TERMSiii EXECUTIVE SUMMARYA permeable reactive barrier (PRB) filled with zero-valent iron (ZVI) was installed at former Naval Air Station (NAS) Moffett Field in April 1996 and monitored periodically for the next 8 years. This pilot-scale PRB intercepts the more concentrated core of a relatively large regional groundwater plume of CVOCs that is approximately two miles long and a mile wide. The primary objective of this report is to describe the results of the last round of monitoring conducted in July 2004, their relationship to the results of pervious rounds, and their implications for the longevity and hydraulic performance of the PRB.The primary contaminant in the plume is trichloroethylene (TCE). Considerable amount of cis-1,2 dichloroethylene (DCE) is also present in the groundwater, thus indicating that some natural attenuation through anaerobic reductive dechlorination is underway at the site. The cleanup targets for these two compounds are the same as the federal drinking water standards or maximum contaminant levels (MCL) of 5 ppb (TCE) and 70 ppb (DCE).The long-term monitoring of this PRB showed that the ZVI continues to react strongly with the chlorinated volatile organic compounds (CVOC), primarily TCE and DCE, present in the groundwater. For the first time in July 2004, there were signs that a treated water front was exiting the PRB, fl...