SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Mike Infurna [EH] From: Jim Barton [jbarton@waterboards.ca.gov] Sent: Tuesday, June 30, 2009 6:10 AM To: John Carrow; Mike Infurna [EH] Cc: Paul Anderson Subject: Re: Well Installation at Lincoln St. Hi John, Mike gets in around 0800 hours PDT (1000 hours CDT) , so we can talk then. Or let me know what time works best for you. Thanks. Jim James L.L. Barton, P.G. Engineering Geologist California Regional Water Quality Control Board Central Valley Region, 11020 Sun Center Drive, Suite 200, Rancho Cordova, CA 95670 office (916) 464-4615 fax (916) 464-4704 >>> "Carrow, John" <JCarrow@pscnow.com> 6/29/2009 9:06 PM >>> Jim, I thought I would give you a heads up on our situation out here in Stockton at Colombo Toscana. We drilled the boring for the 80 foot well located near the Texaco well No. 14 on Tuesday the 23rd. This is the well about fifteen feet east of the sidewalk of Lincoln St. The rig we were using had a difficult time getting through 50 to 60 foot zone mainly because of the weight of the rig. We encountered sand at 65 feet with silty sand and thin sand layers to 80 feet. We decided to stick with the plan and install the well with a TD of 80 feet. Well installation appeared to go smoothly with the exception that the well wanted to float up in the auger. The next day we drilled the boring for the 120 foot well about 4 feet west of the 80 foot well. The geology was identical based on the drilling and the cuttings. We encountered a coarser grained sand at 85 feet but we unable to collect a sample because we had no catcher in the shoe of our sampler and it was difficult to determine what was slough and what was sample. Cuttings and the slough were a medium to coarse grained sand. The 90 foot sample and every sample after that was a silty clay with no sand and only a damp moisture content. We continued this boring to 130 feet but based on the difficulty in sampling and the lack of water, I decided that a well installed at this depth would be dry or produce very little water. We abandoned this hole as a boring. When we arrived to develop the 80 foot well today we found filter sand from the boring up to 40 feet. We don't know what happened but we speculate that the casing broke when we were installing the well and trying to hold it in place. We must have poured sand directly into the casing and screen. Gregg Drilling will fix this well in accordance with CA regs. I would like them to over drill and remove the casing. Drill the well to 87 feet and place 10 feet of screen from 77 to 87 feet. This would straddle the sand we encountered in the 130 foot boring. Our grout inspector from San Joaquin County is out of the office until Friday. When I called they referred me to Mike, who suggested we contact you to discuss my proposal for fixing this situation. Mike has voiced concerns about sealing off the permeable formation in the 70 to 80 foot range. I believe that if Gregg does this correctly and we drill down the additional 7 feet we can have a better producing well than a well with an 80 foot TD. Some added information, the well installed east of the Colombo Toscana building was screened with a TD of 119. 1. This was developed by bailing, surging and pumping. We removed 160 gallons from the well at a pumping rate of approximately 0.65 gpm. We were not able to sustain a higher pumping rate. I feel confident that the replacement well installed with a TD of 87 feet will be capable of similar if not better discharge. 1