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Kennedy/Jenks Consultants <br /> t' 3IR IEngineers and Scientists <br /> L IN V I R O N i41 E 1•i ! M L HEALTH Marathon Plaza, Tenth Floor <br /> "—i4^!' "�=C 303 Second Street <br /> i'v�.. San Francisco,California 94107 <br /> 28 August 1991 415-243-2150 <br /> FAX 415-896-0999 <br /> Mr. Michael Higgins <br /> Regional Water Quality Control Board <br /> 3443 Routier Road, Suite A <br /> Sacramento, California 95827-3098 <br /> Subject: Lincoln Village Center <br /> Well Destruction Proposal <br /> K/J 900109.40 <br /> Dear Mr. Higgins: <br /> Thank you for the opportunity to review the destruction proposal for San Joaquin County <br /> (Lincoln Village Maintenance District) wells Number 1, 2, 4, and 6. As you are aware, <br /> wells 1, 2, and 6 penetrate through the contaminated water bearing Zone "A" at Lincoln <br /> Village Center (LVC). Therefore, it is important that these wells are properly destroyed to <br /> minimize the possibility that they will act as conduits for the vertical migration of volatile <br /> organic compounds (VOCs). Based on our preliminary review, we have a number of <br /> concerns regarding the adequacy of the proposed well destructions to provide protection <br /> against the vertical migration of VOCs to the lower water bearing zones. <br /> In general it should be noted that the recommendations of the current proposal does not <br /> appear to address the specific lithology in the area. We believe that at a minimum, it will <br /> be necessary to puncture the blank casing and pressure grout the well throughout the <br /> depths corresponding to suspected aquitards, therefore creating an adequate seal within <br /> the formation. Based upon our lithologic evaluation of the area, we have defined a Zone <br /> "C" aquifer from a depth of approximately 180 to 260 feet. A well defined aquitard <br /> apparently exists from a depth of 140 to 180 feet. All well casings should be punctured <br /> or ripped and the formation pressure grouted throughout this zone. Tile remaining <br /> lithology consists of thinner clay and sand zones. Because of this, we would recommend <br /> that casing from 40 to 180 feet be punctured and pressure grouted to provide protection <br /> for intermediate water bearing zones. Based upon this evaluation, we would like to <br /> recommend the following changes to the proposed destruction of each well. <br /> Wells 1 and 2 <br /> It appears that wells number 1 and 2 have been mislabeled. Based upon our recent <br /> videotapes, well number 1 is open to a depth of approximately 187 feet, below which the <br /> well is filled with sediments. The casing is perforated from a depth of 164 feet to the <br /> bottom of the well. Well number 2 showed no evidence of cave-in, and was open to a <br /> depth of approximately 275 feet. Perforations were located from a depth of 212 to 252 <br /> feet. Both of these wells should be destroyed as previously discussed. <br />