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Ms. Gail Wiggett Project 20C42-001.026 <br /> June 25, 1998 <br /> Page 2 <br /> Well Standard). Thus, the weighted tape passed through the upper 5 feet of the grout <br /> column. The tremie pipe was removed from the hole and the well casing was pulled. <br /> Approximately 44 feet of casing were removed. A second firm tag of the grout indicated <br /> the level was approximately 10 feet bgs. Tremie pipe was replaced to 15 feet bgs. The <br /> grout resumed at 4:20 P.M. An additional 5 cubic yards of grout were placed to ground <br /> surface. This quantity included approximately 2.5 cubic yards to fill the void from the <br /> concrete pad wellhead. <br /> ISSUES <br /> Prior to and after placement of the initial four cubic yards of grout, several issues were <br /> raised. These issues and respective responses are presented as follows: <br /> • The plan to remove the casing and tremie grout the borehole was a significant <br /> deviation from the proposed perforation and pressure grout method outlined in <br /> the workplan. <br /> — The well driller's log indicated that the well had a 10-inch-diameter casing, but <br /> the actual casing was 8-inch diameter. The wellhead was removed to determine <br /> if a 10-inch-diameter casing was present as an outer sleeve, enclosing the <br /> observed 8-inch-diameter casing. No other casing was present and the annular <br /> space was open to the formation. EMCON verbally notified you of these <br /> observations 3 days prior to the well grouting activities and indicated at this <br /> time that we would remove the casing in the interval to 55 feet to meet the <br /> intent of Section 13.17.6 of the PHS/EHD Well Standards. Removing the <br /> casing allowed direct contact of the grout with the formation over the interval <br /> grouted. <br /> • The grout required at a groundwater contamination site in San Joaquin County <br /> consists of either neat cement, cement containing up to 4 percent bentonite, or a <br /> 100 percent bentonite grout. <br /> — The initial grout order was a 10-sack mix, consistent with state standards. <br /> Upon arrival of Ron Rowe and discussion of the grout mix, the grout <br /> requirements were discussed and the grout order was changed to neat cement <br /> consistent with the county requirements. <br /> • Grout must be placed in a continuous pour to 5 feet bgs. <br /> SACW:\P1POC4nC420012.6DE-9Nba s:I <br />