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Reporting Period September 8, 1997 -September 15, 1997 Page 2 <br />Main Crossing (Wall F-1 and F-2) In Progress Complete 9/26 <br />Wall G In Progress Complete 9/19 <br />Pond SG-1 and Culvert CCW-1B In Progress Complete 9/26 <br />Wall H Completed 9/11 <br />Water Tank Extension Indefinite Hold <br />Lower Sylvester Gulch Road Begin 8/27 Complete 10/3 <br />Field Observations, Data Collection, and Ongoing Evaluations <br />A complete inspection was performed by MCC on September 13, 1997 to visually observe and <br />evaluate the stability of slopes within the project area. Data collection efforts and evaluation or <br />re-evaluation of specific areas of concern continues. Individual areas are discussed in detail in the <br />following sections. Supporting documentation is attached for your review. <br />Lower Sylvester Gulch Road: Clearing and topsoil stripping has been completed on <br />approximately 98% of the lower Sylvester Gulch Road. Excavation work is in progress in <br />areas where water and slope stability issues are not of concern (between Stations 37 and 50), <br />and drainage control measures are being installed above or at the top of other cut slopes in <br />advance of major excavation work. Observation of the cleared slopes showed no failures or <br />slumping on September 13, and no previously undiscovered springs were exposed. In <br />addition to planned drainage facilities, MCC plans to dewater (via french drains) any springs <br />or groundwater encountered during excavation of the benched slopes, and has approximately <br />2000 feet of additional slotted pipe on-site to be prepared for this possibility. <br />The latest reading on inclinometer I-2 (September 12) shows the same small creep type <br />movement as previously observed and reported. Inclinometer I-2 will be unaffected by <br />construction and will be maintained and monitored during construction and for the long term. <br />Most of the survey prisms placed earlier this year are also unaffected and will remain in place <br />for long-term surface monitoring. Additional monitoring installations, including replacement <br />mirrors and a replacement for inclinometer I-4, are planned, and the locations of other <br />potential piezometers and inclinometers are being evaluated. <br />Upper Sylvester Gulch Road: On Wednesday, September ]0, a new failure was reported <br />and observed at the previously failed fill area at approximately Station 63+50. The failure <br />occurred in a previously disturbed section of the cut slope, between the construction haul road <br />and the existing top of the cut slope, and appeared to be a continuation or reappearance of <br />one of the scarps that occurred during the initial failure in early July. The failure mass was a <br />distinct semi-circular wedge of soil approximately 8 feet high by 8 feet thick by 60 feet long <br />that split off the cut slope and dropped approximately 6 feet, however, the scarp did not <br />extend into the roadway. The failure was probably caused by excavation efforts, which had <br />created a steepened slope in this location during removal of previously placed fill material. <br />The Contractor was directed to regrade and flatten the slope and re-establish drainage, and no <br />additional cracking was observed later in the week. Surface surveys continue to indicate no <br />