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a _ Awl 1 q <br /> ik <br /> NMIk <br /> f <br /> 3. PRESENT INVESTIGA'T'ION <br /> In January 1991 EA installed one injection well, two piezometers,two permanent soil vapor <br /> monitoring cluster wells,° 11 at fonnerne vapor traction Exxon RSwell, <br /> 7-3942 (Figure water <br /> 3) In Febr ary three addi- <br /> groundwater monitoring <br /> tional vapor extraction wells were installed after the construction of a planned shopping center a <br /> the site was delayed. After the access permit was granted in April, a groundwater monitoring <br /> well(MW 11)was installed on the parking lot of Crestwood Hospital(figure 2). <br /> 3.1 BOREHOLE DRILLING <br /> d 21 January, Ig February,and 17 April 1991,a total of 12 boreholes <br /> During the weeks of 14 an <br /> were drilled with a rotary drill at the locationshollow <br /> -stein <br /> show in Figur�si2land 3`VeW�}slwc eCnst.tiled <br /> (License Number C57:4g2390) <br /> under permits from San Joaquin County Public I-lealth Services, Environmentalov1calt}w Division, <br /> vis[ll- <br /> and City of Stockton Public Works Department(wells MW 12, RW4,V3) the d A. <br /> Th sail sampling,and well a[nassllation,which ortment of depths,depending onprotocol <br /> purpose of the well. <br /> The borings were drilled <br /> 3.2 INSTALLATION OF GROUNDWATERISOIL MON ITORINGIEXTRACTION <br /> ,WELLS <br /> boundary <br /> tile site <br /> On 15 January one injection well�(,WWFI!createinstalled <br /> hyd�aulic barrien tile western <br /> isolttting the <br /> site from asuss- <br /> 3). Injection of water into this . e of <br /> round- <br /> pected offsite source of petrol cntndiredctionr Static groundwbons and ater was encounearea of t <br /> ered abottt30 feet <br /> water extraction in the upgrad <br /> below ground surface with and 1 25 well <br /> hollow stem aleted uger. Thefeet bgs tn a well�tw stconstruct d with <br /> borehole was drilled with a <br /> 4-inch-diameter Schedule 40,flush-threaded PVC pipe. The well screen consisted of 0.020 inch <br /> slotted PVC pipe. <br /> In order to monitor the performance of IW: (and monitoring wells MW4 and MW7 that will be <br /> tes,two piezorneters <br /> used for injection)in creating a showcn n Figunt ee 3�tTl ejboie two rel oles were drilled with an(g finch) <br /> were installed at the locations <br /> diameter hollow-stem auger. The piezometers were constructed with 2-inch-diameter Schedule- <br /> 40 <br /> che u e40 PVC pipe. The well screens consisted of 0.020-inch slotted PVC pipe. <br /> On lb January two soil vapor monitoring cluster wells (PSV 1, <br /> PSV2) were installed at the loca- <br /> tions shown in Figure 3. Each cluster well was designed to monitor vapors at two diff erent <br /> feet <br /> s and tile <br /> depths. Separate 1-ince casings,one screened 7-12 feet screened intervals were intentionally pl^cod]n strati of sanu er screened 29.` "or silt in <br /> bgs, were installed; the <br /> each boring; the sand pack extended from the bottom of the screen to one Foot above eac.+ <br /> G <br /> . ,6Y�.MY7+Yim4ll� <br />