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Natalia ... • From: Robert McClellon [EH] Sent: Monday, December 22, 2014 3:59 PM To: Natalia Subbotnikova [EH] Subject: FW: Double -screening for new groundwater well MW -6 at Foothill Landfill From: DelFrate, Todd@Waterboards [ma ilto:Todd. Del Frate@waterboa rds.ca.gov] Sent: Tuesday, November 25, 2014 9:47 AM To: Taj Bahadori Cc: Hold, Howard@Waterboards; Michael Carroll; Joyesh Chandra; 'Isham, Julian'; DelFrate, Todd@Waterboards; Robert McClellon [EH] Subject: RE: Double -screening for new groundwater well MW -6 at Foothill Landfill Taj, thanks for the overview of valley GW conditions and the review of GW elevation data at the foothill landfill. Staff has reviewed the revised well design submitted and is concerned the design now being proposed is penetrating 40 feet of water bearing zone. The County has not provided any geologic evidence that a continuous water bearing zone at this site exists. Furthermore, staff had approved a work plan with a well design that is similar to well MW -5. This design is a more sophisticated and complex design that requires greater scrutiny. As such, by 9 January 2015, please revise and submit a work plan that reflects the design change and describe the rational for the design change. Secondly, prepare geologic cross sections with all site groundwater wells to characterize the subsurface conditions. Include screen intervals and historic high and low groundwater elevations and last known VOC detections at each well. Foothill Landfill is a large site with data points spaced at great distances, reducing confidence in subsurface details. Please do not overextend your knowledge of the underlying geology without supporting data. A proper assessment will take several cross sections to flesh out. Staff will send a formal letter for the file. Any questions let me know. We look forward to your revised work plan. Thank you. From: Taj Bahadori [mailto:tbahadori@sjaov.ory] Sent: Monday, November 24, 2014 4:17 PM To: DelFrate, Todd@Waterboards Cc: Hold, Howard@Waterboards; Michael Carroll; Joyesh Chandra; 'Isham, Julian' Subject: RE: Double -screening for new groundwater well MW -6 at Foothill Landfill ••• The Central Valley has been in overdraft for several decades. Last year the County had to replace one well at the Foothill landfill (MW -1), two wells at the Harney Lane landfill (MW -3 and MW -4), and two wells at the North County landfill (G-2