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r WESTERN GEO-ENGINEERS <br /> SECTION 5.2 <br /> MONITOR WELL CONSTRUCTION <br /> Upon completion, the exploratory boreholes were converted into ground water <br /> monitoring wells. Thesa monitoring wells were constructed using 2" diameter <br /> schedule 40 "PVC" blank and factory slotted (0.02") casing with threaded flush <br /> joints. No solvents or cements were used. The wells were installed to monitor the <br /> upper most water bearing stratum with care to allow for water level fluctuations. <br /> pp zein was <br /> Well construction details are presented in Appendix A. After the casing <br /> installed the annulus around the screen section of the well was filled with clean <br /> medium aquarium sand (100% retained on #35 sieve), then a sounding (a weight <br /> attached to a measuring tape was lowered into the auger until tension on the 'ape <br /> decreased, indicating the weight was resting on top of the sand) was performed to <br /> determine the level of sand prior to staging out (retrieving) a five foot section of the <br /> auger. This procedure of filling the annular space with sand, sounding to check <br /> level of the sand and pulling or staging out a five foot section of auger was repeated <br /> until the sand filled the annular space four to five feet above the top of the screen. <br /> After the sand pack was in place the remaing auger was removed and another <br /> sounding made to varify that the sand pack had filled the annular space to the <br /> 4 proper level. A six inch neat cement seal was'then placed above the sand pack to <br /> prevent the next seal (6" hydrated bentonite) from working its way into the sand <br /> Following the bentonite seal a cement grout was <br /> pack and into the screen slots. <br /> then placed in the ainnulus to within one foot of the surface. This surface seal <br /> placement was witnessed by an inspector with the San Joaquin County Health Dept. <br /> The "PVC" riser was then protected by barricades until a traffic box could be <br /> installed once contruction of the station was allowed to proceed and final grade was <br /> realized. Trafic box installation was completed by Walton Engineering on June 22, <br /> iJ88. <br /> s <br /> 6 <br /> I� <br /> 1 <br /> page 16 <br />