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Sylvester Gulch Piezometers <br />East Fork: <br />Piezometer 97-89 is not showing a reduction in the ground water table since the spring thaw. The <br />ground water levels at this location have been stable since March 2005 at 34 feet below the ground <br />surface. The existing 2nd quarter 2006 ground water level is the highest recorded since 1998. <br />Uooer West Fork• <br />Ground water levels in piezometers 97-149 and 97-154 measured during the 2°d quarter 2006 have <br />increased by 4 feet since August 2005. <br />Between F-Wall and East Fork and F-Wall: <br />Piezometers 97-102, 97-110, 97-111 aze still showing generally increasing trends in Bound water <br />levels since 2005 that exceed the general seasonal fluctuations. Jn particulaz, the Bound water in <br />piezometer 97-I11 has increased by at least 29 feet since 2005 and ground water levels reached <br />within 2 feet of the ground surface. Since the spring thaw the ground water levels at this location <br />have decreased slightly (by 3 feet) however, ground water is still within 5 feet of the ground <br />surface. During the 2°d quarter 2006, the ground water measured at F-Wall has shown increases by <br />7 feet since August 2005. The ground water at this location is now within 37 feet of the ground <br />surface. <br />The high ground water levels measured at this location coupled with the displacement of the F-Wall <br />recorded last year during the annual structural review aze a concern. It is recommended that the <br />ground water levels in each of these piezometers be measured in subsequent months. The integrity <br />of the F-Wall will also be checked during the annual structural review for 2006, and if additional <br />displacement and degradation is found (since that noted in 2005) it is suggested that remedial action <br />be undertaken. <br />Road to Sylvester Gulch: <br />The ground water in piezometer 98-49 has been generally increasing since 2002 and is currently up <br />approximately a total of 3 feet. This increasing trend is a concern because the ground water is <br />within 15 feet of the ground surface and may cause instability in the colluvium material triggering a <br />landslide. <br />t The ground water in piezometer 98-56 has been generally increasing since 2002 (up approximately <br />7 feet). During the 2°d quarter 2006, the ground water level at this location continued to increase <br />and is currently at approximately 40 feet below the ground surface. The ground water level in this <br />' piezometer will be monitored closely in future months to track the increasing trend and determined <br />if remedial action may be required. <br />The ground water table measured in piezometers 98-52 and 98-56 are showing gradual increases in <br />the ground water table since August 2005, without any decrease post spring thaw. <br />Barr Engineering Company 2n° Quarter 2006 <br />06/26-031 Geotechnical Monitoring <br />