ARCHIVED REPORTS XR0009291 - Laserfiche WebLink

Home Browse Search

I Geological reelutles Inc Page 2 Groundwater Monitoring Report Project No 723 2 June 20,2005 ' b GTI, the CMTTM wells were so tightly coiled from shipping that it was difficult to install Y � g Y pp g ' the wells without the tubing corkscrewing in the borehole, even when the casing was stretched out on the ground in the sun to warm and relax the coils The result of this twist in the tubing is that depth to water measurements could not be made because the instrument ' probe becomes lodged in the small chambers of the tubing Subsequently, Del-Tech Geotechnical Support has procured a micro-water level meter that can be used in the CMTTM wells The first quarter of 2005 was the first time that the well chambers could be sounded and they are now included in the quarterly monitoring scheme Groundwater gradient calculations show that shallow groundwater flow is N59°E at 0 0034 ftIft This is consistent with the site's historical directions that have been predominantly to the northeast The intermediate and deep aquifer zones' gradients were calculated to be N5311E at 0 004 ft/ft and N55°E at 0 0038 ft/ft, respectively The deepest aquifer zone gradient monitored by wells MW-101, MW-307, MW-308 and MW-309 was calculated to be S31°W at 0 0025 ft/ft This direction is anomalous to the other three calculated gradients but additional monitoring is needed to determine trends with the inclusion of the CMTTM wells Field evidence recorded during borehole installation indicates that petroleum hydrocarbon contamination is present on the adjacent property across N El Dorado Street—an active Shell service station The Valentine (Castle Motors) site plume extends off site toward the Shell Station and evidence suggests that a co-mingled plume may be present The lateral extent of the groundwater plume is undefined down gradient of CMTTM well set MW-8/108/208/308 ' A limited site investigation should take place to define the down gradient extent of the plume This should consist of direct push probe drilling methods such as CPTTM to collect discrete groundwater samples rather than installing additional monitoring wells A work plan to accomplish this task has been sent to SJC/EHD for approval ' We have recommended that interim remediation be considered before this plume migrates any further and the cost for cleanup continues to increase A work plan for interim remedial action utilizing high vacuum dual phase extraction, air stripping and carbon filtration of extracted groundwater technologies has been sent to SJC/EHD for approval SJC/EHD approved the work plan in their March 7, 2005 letter and the costs for the extraction and treatment system procurement, installation, and operation is underway Our goal is to have the interim remedial action plan installed and operational by the end of 2005 1 1