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From: DelFrate, Todd@Waterboards [mailto:Todd.Del Frate@waterboards.ca.gov] Sent: Friday, November 21, 2014 8:49 AM To: Taj Bahadori Cc: Hold, Howard@Waterboards; Michael Carroll; Joyesh Chandra; 'Isham, Julian'; DelFrate, Todd @Waterboa rds Subject: RE: Double -screening for new groundwater well MW -6 at Foothill Landfill Taj, staff understands your concern. However, before staff concurs please provide a table of historical groundwater elevations from site wells that backup your assertion of a declining water table. What is the expected decrease annually? What has the decrease been over the last five, ten, fifteen years, etc. This will help staff concur with the modified well construction. Please provide as soon as possible so that staff may provide a concurrence and the project proceeds on schedule. Thank you. From: Taj Bahadori [mailto:tbahadori@sjgov.org] Sent: Thursday, November 20, 2014 3:20 PM To: DelFrate, Todd@Waterboards Cc: Hold, Howard@Waterboards; Michael Carroll; Joyesh Chandra; 'Isham, Julian' Subject: FW: Double -screening for new groundwater well MW -6 at Foothill Landfill Hi Todd, As you know the water table has substantially dropped in the valley and probably will continue to drop in the future. We are concerned that we might have to re -drill deeper wells at our landfills. Regarding our new well MW -6 at Foothill, we would like to propose installing a double -screened well (design attached). This well would have two screened intervals separated by an inflatable "packer" (photos attached). This allows us to sample the top ten feet of the aquifer, and only when the groundwater declines below the first screened interval, we can take out the packer and pump, insert the pump into the lower screened section, and collect samples from the lower section. This will prolong the life of the well and save us the expense and trouble of having to re -drill a new well a while longer. We have drilled 2 similar wells at Corral Hollow landfill and Kim Schwab was involved with those well constructions. The Corral Hollow design included three screened intervals, with sand and bentonite inside the riser (rather than a packer) separating the upper from lower screened sections. When an upper section goes dry, the separating bentonite and sand will be blasted out with water. The disadvantage of this method is that the blasted bentonite and sand cause turbidity and sampling has to be delayed until the groundwater clears. The packer, on the other hand, can be easily removed and GW sampled immediately. We have spoken to our vendor; Greg Drilling, and they have constructed this type of well and are familiar with the packer process. I have attached a picture of the packer. The Viton body packer is used widely in environmental work, is inert in water and does not add any VOCs. Please let us know if this is acceptable. We are hoping to install this well in December and start monitoring the well before the end of the year. Thanks, Taj 209-953-7316 Iq