Permits & Development - Encroachment(EP)/Driveway(DW) Permits - 2012_PS-1201501 thru PS-1202000_ - PS-1201992

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Mr. Gil Moore July 13, 2012 6437 Banner Street, Lodi Page 3 of 3 Well Destruction Work flan between the older outer annular grout seal and the younger inner grout seal. This may be aggravated by silt and clay suspended in the eater in the well during the casing removal that may be trapped between the older and younger grouts_ A continuous pour means that each additional pour will intermingle and set up as one pour. Should the attempt to pull out the well casing be unsuccessful, movement of the casing without co-movement of the grout seal of even a fraction of an inch will break what seal exists between the casing and the annular grout seal. Jarring the casing without appreciable movement may do the same. This could create a vertical conduit between the well casing and the annular cement grout that may not be addressed by pressure grouting as proposed. The proposal to over-drilling the wells down to the saturated zone, presumes the annular grout seal maintains a good seal with the well casing in the saturated zone. This is applicable only with a bentonite grout seal, but not necessarily with a portland cement grout and a PVC casing, such as is the situation at the subject site. The 'popsicle' destruction method that EHD has found to be successful was applied on shallow wells of fifteen or less feet in depth and constructed with a neat cement grout seal of not more than five feet below grade. The well is removed by pulling out all in one piece the surface cement pedestal, casing; and intact cement grout adhered to the casing. The filter pack remained at the bottom of the well. EHD has determined that it is less of a concern if the filter pack remains at the bottom of the well in the sand strata and that this method meets the intent of Section 13.17.6, of the Standards. Due to the issues noted above, the proposed AGE 'popsicle' method is acceptable provided the casing is successfully removed and the entire cement seal remains attached on the removed casing. If the casing is not removed entirely, or the original cement seal remains in parts or entirely adhered to the borehole, then the well and boring must be over-drilled to full depth of the original well to remove all materials used to construct the well. The resulting borehole rnust then be sealed from bottom to surface with an approved sealant that is under pressure using a tremie pipe. If you have any comments and/or questions, please contact Nuel Henderson at the address noted on this correspondence or telephone him at (209) 468-3436. Sincerely, Nuel Henderson, PG ✓Adrienne Ellsaesser Engineering Geologist Acting Program Coordinator c: CVRWQCB—James Barton, Sacramento c: SWRCB-CUF -- Mark Owens, Sacramento c: San Joaquin County 'UMD -- Steve Winkler U AGE —Timothy Cuellar