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March 16, 1988 <br />Roberts Oil Company <br />Page 9 <br />Materials to be used for construction of the ground water quality monitoring <br />wells will include 2 -inch I.D. interior/exterior flush threaded PVC Schedule <br />40 casing. Well screen perorations will be precision machine slotted. <br />Screen slot sizes will be 0.20 inch, or as determined by hydrogeologic <br />conditions. Screen/casing strings will be threaded together. The use of <br />solvent glues will not be allowed in assembling the screen/casing strings. <br />Gravel pack material will be clean, rounded, water -worn material, and will <br />b,5 installed in the annular space adjacent to the well screen, to a distance 1 <br />to 2 feet above the top of the well screen section. Within the annular space <br />above the gravel pack material, a 2 foot thick granular bentonite slurry will <br />be placed as a seal. The remaining portion of the annular space will be <br />sealed with a cement/bentonite slurry to ground surface.- To protect the <br />monitoring well from accidental damage or tampering, a traffic rated box <br />will be placed over the top of the well, at grade, with an Internal locking <br />cove r. <br />Task 6: Well Development <br />After construction and installation, the ground water quality monitoring <br />wells will be developed to improve the hydraulic conductivity between the <br />wells and the natural formation. Well development will consist of manually <br />bailing or mechanically pumping to remove residual silts and clays left from <br />the drilling operations. At least ten (10) well volumes of ground water will <br />be removed. After development, the well will be allowed to recharge for <br />approximately 24 hours, enabling Exceltech to collect a representative <br />ground water quality sample, and to measure the thickness of any floating <br />product. Ground water generated by the development efforts will be <br />drummed, and stored onsite. Should the laboratory analytical results of <br />ground water quality samples collected from the installed wells under Task <br />7 indicate that ground water is contaminated, it shall be the responsibility <br />of Roberts Oil Company to properly dispose of any contaminated water. <br />Exceltech can assist Roberts Oil Company in making arrangments for <br />transportation and disposal of any contaminated water on a time and <br />material cost basis. <br />