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13. Contractor shall install a bentonite seal in the annular space above the <br /> sand pack. Add bentonite gradually to avoid bridging. Contractor shall <br /> measure the depth of the bentonite plug using a weighted tape. <br /> 14. Contractor shall hydrate the bentonite seal after placement with five (5) <br /> gallons of distilled or Engineer-approved water for each 2.5 vertical feet of <br /> seal. <br /> 15. Contractor shall add sufficient water to hydrate the bentonite. Contractor <br /> shall add water to the bentonite seal and allow the bentonite to.hydrate for <br /> minimum of 30 minutes. Contractor shall measure the water elevation over <br /> the bentonite after adding water and again 30 minutes later. If water <br /> elevation has dropped during that time, then Contractor shall wait for <br /> another 30 minutes before grouting with neat cement. <br /> 16. Contractor shall pump neat cement through a tremie pipe filling the annular <br /> space from the top of the bentonite seal upward. The bottom of the tremie <br /> pipe shall be maintained below the top of the cement to prevent free fall <br /> and bridging. <br /> 17. Contractor shall place neat cement in a single pour for wells up to 100 feet <br /> deep. For wells deeper than 100 feet, the Contractor shall pour neat <br /> cement in two pours, the second pour being at least 24 hours after the first <br /> pour. <br /> 18. When drilling with hollow stem augers, the hollow stem of the auger may <br /> be substituted for the tremie pipe, provided the bottom of the augers are no <br /> more than 10 feet above the top of the neat cement layer within the well. <br /> 19. Contractor shall place neat cement in the boring up to the existing grade. <br /> Contractor shall allow neat cement to settle overnight. After neat cement <br /> settlement, Contractor shall place additional neat cement to a level as <br /> indicated in the construction figures. <br /> 20. Contractor shall install the well enclosure and do the surface completion <br /> only after the neat cement has hardened. <br /> E. Contractor shall record the following information on the Drillers Log: <br /> 1. Depth to water-bearing zones <br /> 2. Total depth of bore hole <br /> 3. Depth from ground surface to top and bottom of the well screen interval <br /> 4. Depth from ground surface to top of the sand pack interval <br /> 5. Depth from ground surface to top of the bentonite plug <br /> 6. Height above the ground surface of the top of the well casing <br /> 7. Height above the ground surface of the top of the steel protective casing. <br /> San Joaquin County <br /> Groundwater Monitoring well Specifications 8 Public Works Dept <br /> Solid Waste Division <br />