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Memo to Dave Berry Bowie No. 2 Third Supplemental Response page 4 '...extensive detail will have to be provided to describe the collection and diversion of these ground waters and the long term stabilization of the potentially effected 80 foot high cut slopes and 50 foot high fill embankments. This will constitute both a significant operational facility and reclaimed configuration design challenge.' " "In the conclusion of this additional geotechnical study, Maxim Technologies states; 'We do not believe expansion of the reclaimed slope fill to be a concern for the long term stability of the slopes.' This totally unsupported conclusion, which appears in contradiction to Maxim's earlier statements will require specific justification. I suspect, that under saturated (swollen) conditions these soils may exhibit altered material strength characteristics. Further, the altered strength of the swollen soils may significantly change the stability of reclaimed fills constructed of these materials." In support of MAXIM's conclusion, Mr. Stover presents his opinion of the two fold basis for their statement within his January 21, 1997 submittal letter. Mr. Stover's first justification is as follows: (a) "As per Maxim ;s recommendations, the reclaimed fill is to be placed with a mositure content at or above optimum moisture and compacted to at least 85% of the maximum modified Proctor density. At optimum moisture, the majority of the void space within the soil structure is filled with water so the soil will not have a willingness to accept water and swell. Therefore, a fill placed to this specification will not accept extenbsive mositure and therefore will not swell enough to cause strength deterioration." My experience, related above, leads me to disagree with Mr. Stover's scvenario for expansive soil performance. In the short term, if carefully controled during placement, sensitive soils can be compactedto 85% of the maximum modified Proctor density. In the short term, many of these soils will perform acceptably. During the operation of the mine when stringent maintenance of surface drainage is practiced, these soils may perform acceptably. Following reclamation, however, under conditions of little or zero maintenance, many of these fills will be exposed to increased moisture. Under saturated or super-saturated conditions, these sensitive soils will experience the swell response determined by MAXIM and reported within figures 8 through 13 in their July 10, 1997, "Preliminary Geotechnical Engineering Study" (Section 2, Volume VII). In the worst case, as depicted in figure 10 of this report, a soil exhibited an approximate 13% volumetric expansion when saturated. If this were to occur within a backfilled soil wedge originally placed at 85% relative density, the final expanded soil density might