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Groundwater and River Monitoring
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2007 - 2008 Accomplishments
- Over 214 samples were collected from the Colorado River and over 395 groundwater samples were collected from wells during 2008. Installation of 8 additional groundwater monitoring wells was completed in 2008, bringing the total number of wells to more than 120. Three new river channel sampling locations were added, bring the total to 12.
- The Upland In-Situ Pilot Study was completed in December 2008. Post completion monitoring will continue into 2009.
- The Revised Work Plan for East Ravine Groundwater Investigation was approved by DTSC in July 2008 and DOI in November 2008.
- The first phase of the supplemental soil investigation was completed in October 2008. More than 700 soil samples were collected in nine areas outside the compressor station.
- A Corrective Measures Study (CMS)/Feasibility Study (FS) Work Plan was approved by DTSC on June 13, 2008.
- The Floodplain In-situ Pilot Study was completed in late 2007 and a completion report was submitted in March 2008. Results show in-situ to be a successful remediation technique for hexavalent chromium; three out of four pilot test wells had reductions of hexavalent chromium from thousands of parts per billion (ppb) to less than 0.2 ppb in just six months. Post completion monitoring will continue into 2009.
- The Final RFI Volume 1: Site Background and History was approved by DTSC and DOI in August 2007.
- Five slant wells (in 2 well casings) were installed on the California shoreline in spring 2007. These angled wells allow for samples to be collected from groundwater in soils below the bottom of the Colorado River, for the purpose of delineating the southern extent of
groundwater affected by chromium.
- Five new vertical wells and three new slant wells were installed on the Arizona shoreline of the River during March and April 2008. These wells allow for groundwater samples to be collected for the purpose of delineating the eastern extent of groundwater affected by chromium.
- A programmatic (overarching) Biological Assessment was completed in January 2007 to cover remediation and investigation projects at the Station up to the final remedy. For habitat improvement, approximately 400 mesquite trees were planted on the Havasu National Wildlife Refuge and a drip irrigation system was installed to ensure their survival.
- Annual monitoring determined that no archaeological or historical sites were affected by field activities in 2007. Route 66 was nominated for the National Register of Historic Places and the protective covering over Route. 66 continues to be monitored and maintained throughout all field activity.
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