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M • Page 1 of 2 • Mike Infurna [EH] From: Amy Terrell [aterrell@waterboards.ca.gov] Sent: Wednesday, March 09, 20112:23 PM To: Leonard, Todd Cc: Mike Infuma [EH]; Jackson, Bob Subject: Re: CPS Stockton Cap-Liner Repair During Soil Investigation Thank you for the procedural detail Todd, You are cleared to cut scoop cut bore sample grout fill patch and formally repair the liner once all the borings are completed. I can see why you expect to sample through the liner and seal it up again. Its an ambitious undertaking, but You've got it thought out. The quality of the data you will obtain from beneath the liner will be difficult to obtain any other way. If you have any questions, you may contact me as follows: Amy Terrell Regional Water Quality Control Board Central Valley Region 11020 Sun Center Drive Suite 200 Rancho Cordova, CA 95670-6114 (916)464-4680 aterrel I @waterboards.c@ gov >>> Todd Leonard <tleonard@rubikenvironmental.com> 3/9/2011 1:56 PM >>> Amy, Here is the procedure we will follow to maintain the integrity of the cap/liner system the CPS Stoc during our soil investigation: kton site Prior to advancing the hollow stem auger, an 18 inch diameter section of the asphalt cap will be saw cut (i.e. cored) and removed. The underlying 10 inches of soil will be excavated carefully by hand. A utility knife and/or saw will then be used to cut a 12" diameter hole in the GSE Gundseal liner material to provide access to the underlying soil with the auger. Following completion of the sampling and extraction of the augers, the boring will be filled with the grout material to the base of the liner. The hole will then be backfilled to the base of the surrounding asphalt and a temporary mounded asphalt patch will be installed. After the completion of all of the borings (6 in the north pond and 4 in the south pond), a contractor authorized by GSE for the installation and repair of the Gundseal liner will saw cut and remove enough asphalt around each boring location to provide sufficient area to install a patch on the liner per the manufacturers recommendations (see Section 9.0 in the attached GSE Installation Quality Assurance Manual). Since the patch must overlap the hole in the liner by 12 inches, each saw cut area will be approximately 42 inches in diameter. The soil will again be carefully removed by hand down to the liner. The liner will then be cleaned of debris and dust in advance of installing the patch. GSE indicates that the patch can just be laid over the hole without any adhesive because the bentonite will form a seal; however, the patches installed at the Stockton site will also be 3/14/2011