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Jim Pinasco <br /> October 22, 1992 <br /> Page Three <br /> Recommendation <br /> Intervals that were perforated should have been those <br /> suspected to have a micro-annulus as interpreted from sonic <br /> logging. This recommendation is especially relevant if the <br /> interval with a micro-annulus is adjacent to an aquitard unit. <br /> Comment 4 <br /> On page 3-15, the Draft Report states that an excess of four <br /> cubic yards of cement was pumped into Well 1. <br /> Recommendation <br /> GSU interprets that excessive amounts of grout would not <br /> have been necessary had the aquitard units (not the permeable <br /> units) been perforated. <br /> Comment 5 <br /> On page 3-15, the Draft Report states: <br /> "Due to the apparent high permeability of the Lower Tulare, <br /> as indicated by the inability to raise the water level during <br /> drilling or to draw the well down during well purging, a cement- <br /> sand grout, mixed in the ratio of 7 gallons of water per 94 <br /> pounds of Portland Type I-II cement and 130 pounds of sand, was <br /> used for the first list. . . .The second lift (used) a neat cement <br /> grout, mixed in the ratio of 5. 3 gallons of water per 94 pounds <br /> of Portland Type I-II cement and 2 pounds of bentonite powder, <br /> was used. " <br /> Recommendation <br /> Grout used for the first lift was probably too thin. The <br /> Department of Water Resources Bulletin 74-81 states that neat <br /> cement grout should be mixed at the ratio of 4 .5 to 6 . 5 gallons <br /> of water per 94 pound sack of cement. <br /> The mixing ratio quoted in the Draft Report for the second <br /> lift is questioned by GSU for validity. GSU has not witnessed <br /> bentonite-cement grout mixed with so little water. Typically, <br /> bentonite-cement grout cannot be mixed with less than 6. 5 gallons <br /> of water per 94 pound sack of cement. <br />