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The second well boring MW-10 was completed on April 29, 2006. The boring was <br /> advanced to 41.5 feet below grade surface (bgs) using 8 inch outer diameter hollow <br /> stem augers. Encountered geology was as follows: silty sand was encountered from <br /> surface to 5 feet bgs; from 5 to 15 feet bgs sandy gravel was encountered;from 15 to 20 <br /> feet bgs was gravelly sand; from 20 to 37.50 feet bgs silt was encountered and from <br /> 37.50 to 41.50 feet bgs was sand. First ground water was encountered at 15 feet bgs as <br /> perched ground water. Local ground water was encountered at 23 feet bgs. Monitoring <br /> well MW-10 was constructed on April 29, 2006. The 8-inch boring was reamed using 12 <br /> inch outer diameter hollow stem augers with a wooden plug in the lead bit. The 12- <br /> inch boring was advanced to 40 feet bgs. MW-10 was constructed using same material <br /> as for well MW-11. Bottom of casing was set at 40 feet bgs with screened interval from <br /> 39.5 to 24.5 feet bgs. Filter pack was placed from 40 to 21 feet bgs. The bentonite seal <br /> was constructed from 21 to 16 feet bgs. Grout was placed from 14 feet bgs to grade <br /> level. Well protection features were constructed and consisted of a lockable above <br /> grade steel casing and four steel bollards. Well Details are provided in Appendix A. <br /> City of Riverbank Wastewater Treatment Plant Monitoring Well Installation May 2006 <br /> DE Project No.:109-06 8 Rev.0 <br />