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D. A. Berry - 2 - January 21, 1997 <br />stabilit}~'. BRL will revise this discussion to indicate it will communicate any cut slope, fill <br />embankment, or drainage facility design modification or mitigative implementation to the DMG <br />prior to its implementation. BRL will also indicate it will submit a summary geotechnical <br />construction report to the DMG, summarizing the geotechnical problems encountered, and the <br />mitigative methods implemented during the construction. <br />The memo also requests responses to outstanding geotechnical concerns as follows: <br />1. Inclinometers Monitoring and Reporting <br />The introduction was revised to commit to monitoring and reporting the data from the <br />inclinometers. <br />2. Use of Filter Fabrics <br />The introduction was revised to explain and clarify the use of filter fabrics. <br />3. Expansive Soils Shear Strength <br />The DMG is concerned that in the reclaimed configuration, swelling and low-strength soils <br />will be unconfined and exposed to extensive moisture. In this configuration materials will <br />exhibit their swollen, deteriorated "ultimate" plastic regime strengths. The DMG notes <br />that Maximum makes a "totally unsupported conclusion" when its states "We do not <br />believe expansion of the reclaimed slope fill to be a concern for the long term stability of <br />the slopes". Maxim's conclusion is based on the following two factors: <br />a. As per Maxim's recommendation, the reclaimed fill is to be placed with a <br />moisture content at or above optimum moisture and compacted to at least <br />85% of the maximum modified Proctor density. At optimum moisture, the <br />majority of the void space within the soil structure is filled with water so <br />the soil will not have a willingness to accept water and swell. Therefore, <br />a fill placed to this specification will not accept extensive moisture and <br />therefore will not swell enough to cause strength deterioration. <br />b. Maxim does have considerable experience working with expansive soils. <br />Their conclusion that they do not believe expansion of the reclaimed slope <br />fill to be a concern for the long term stability of the slopes is supported by <br />experience. For the DMG to refer to Maxim's conclusion as "totally <br />unsupported" is inappropriate at best. <br />The DMG notes that Maxim projects the likelihood of encountering significant ground water in <br />the azea of the portal bench, where the highest cuts and slopes are projected to be constructed. <br />Maxim and BRL are puzzled by this concern. Maxim's report states in part: "Based on the <br />available grading plans, the only appazent critical areas for shallow ground water appear to be in <br />