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�MkSWIAIIT nics 2661 MWAPO a CA ssM April 26,1989 Dalton Bietz Lodi Metal Tech P.O.Box%7 r CA;95241 wAr ..,".n �? RE: Addendum to Wcu'h Plan dated 16 November 1988: Project#&.'-'39 Dear W. )Bretz, In response to my'phone conversation with Diane Hinson of San �tacefHealth fdbiet, Emiironmentsl Health Division,.I atm writing this addendum to our preliminary site assessment work plan dated 16 November 19668. The County's matin coikeern is"*.one soil boring would not adequately define the extent of soil contamination at this site,ind that mound water mord",may be necessisay in the futuze. I assured her that we did not intod that.one bodag would fully defame a l problem if it exists,but that we Intended it to 6 a preliminmy 11i66WAMt of the proWft' If the data gathered from tis boring indicates that adder exploratory work is i+eoessary,then we would pet for *at work. That work is outlined below.. 6 Two to three soRborings would be placed at about 30 feet from the center of the excavation and one monitoring well.wouldbe ro lled at a distance of less than 10 beet from where the tank was located(Figaim 2)4.Groundwater gradient will be evvaluated`hom av ble data and the. ging well 0.ac ed downVadient of the tank. A wellt will be obtained if it beconv* apparent that a monitoring well is needed to assess the probWnnu do tie of . is g 1 <;Feet thick,tt well w tem E' It: Otherwise, the well will tete at t a uikes lower bounding aquitud I ay layer). The monitoring well will be constructed of 2 inch threaded-faint PVC plc Whedule 40), perforated from the bottom of the.w H to at least 10 feat above the watttom. Number 3 sand will be used to aioea#e a films pack that adends,from the bottom of themell to 2 feet above the perforated zone. Above the filter pack will be placed a 310 5 foot thick granular bentonite seal. A cement/bentonite gmttt will}a*,pressure insta)led in the annular space above the bentonite seal by using a tt+eutie tom. Thsgrout.n, eture will be as tallows: 10 gallons of;water, 2 pounds(2 pig ire,and one sack of cement. The monis waft wiU-be secured and a surface seal obtained byceiment ing'in a water-tight well box and a`loc.king COP'°A schematic diagram of the well construction is shown in Figure 3.