SITE INFORMATION AND CORRESPONDENCE_FILE 2

Home Browse Search

Page 1 of 3 Mike Infurna [EH] From: Mike Infurna [EH] Sent: Tuesday, November 06, 2007 2:44 PM To: 'ravgeohydrologic@verizon.net' Subject: RE: Best California Gas Ltd SS # 172, 7647 Pacific Ave, Stockton,CA 95207 as for MW-12, ok to drill out to TD plus 1-foot. Ensure the driller has a method (lead tip/rods)to keep the augers centered. MW-12 has 65 feet of grout. The conductor casing (cc)is only 20 feet long. without a lead tip/rods to TD, the augers will drift off the grout from 20' bgs on. The SJCEHD will require MW-12 to be at least grouted from 74' bgs to -3' deeper than anticipated over-excavation will end at. for example, if the pit is 12 feet deep and as the wp says, three feet deeper for o/ex, you may go as deep as 15'bgs. You can either plan on neat cement, cement with 3-5% bentonite (Aqua Gel or Premium Gold) added to cement grout from TD +1 foot (74'bgs)to 15'bgs. A NON hardening grout (bentonite slurry, chips, pellets) is to be used from 15'bgs to the surface to complete the well destruction. THis will allow digging in the pit/at the well column without shattering the cement grout. OR, you may use a NON harding bentonite slurry grout the entire drill out for MW-12 (from TD +1 foot to surface) if you'd like. I offer the cement grout deeper option since it's cheaper for a 10.5" hole from 74' to 15.....your choice- combo grout, or all non-hardening. as for the nested wells, there can be NO lead tip used on the auger and still expect to drill without problems with the overlap and impacting the quarter inch steel cc. The SJCEHD will require BOTH of the casings to be grouted prior to drill out. I recommend thin cement grout w/o bentonite. This will allow casings to be sealed off if the auger drifts off the hole as it passes the bottom of the cc. OK to o/drill with the grout un-set. This will allow an easy drill in case you can manage to stay on center as you drill out MW-1 1 (60'). If not and the augers drift off the original hardened grout from 20' bgs to the bottom of the grout. As and option, If the driller can insert rods down both MW-11 to 60' and VW-3 to 35', then no grout is needed as the augers should stay relatively on center. In the past, I have noticed typical drill rods DO NOT insert into 2" PVC wells. Different rods/inserts are needed. Check with your driller. These conductors casings (cc) are not grouted in. That is, my records show NO grout annulus outside the cc to the borehole. These cc were just placed as protection for future drills in the UST pit and to allow the grout NOT to leak out and grout the USTs in place. The last wells I drilled out with non-grouted cc developed problems and the drillers were not ready to handle them. Long time on site not doing anything waiting for tools/rods/torch/etc got expensive in money and patience. One problem was a spinning cc as the cuttings or missed matched angles jammed it all together. The hoists couldn't pull up the load, they couldn't separate the augers from the cc and no torch was onsite or the USTs weren't inerted to anyones satisfaction to light one anyway...and the site went to...well you can imagine. talk with the drillers to see if they can do something to keep the cc from spinning. If they do spin, see if they can either separate the augers and the cc or be prepared for ???? I recommend a cutting torch and/or other cutting tools are onsite. ensure the tanks are inerted in case of an open flame or sparks from a cutting wheel.. Contamination levels disqualify these wells from being just pressure grouted, as an original option. But I will entertain this option as a last resort, based on field conditions and if no other option is available.. update the work plan to reflect the above conditions and your plans and submit it to me quickly. Make sure the INSTALLATION details for the replacement wells are in this plan too. I'll need at least a map of the location of the wells, construction specs, etc (typical well installation work plan stuff---not enough details in the wp). and do this BEFORE the Executive Summary gets here. then send me the well destruction permit application and $60 fee sometime during the -1-week notification period. update your schedule accordingly please. I'll need to: 1-approve the work plan.(letter) 2- post the site/notify the surrounding populace (letter) 11/16/2007