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resulting in a key depth of only one foot. These areas should be monitored for seepage as mining progresses. The slurry wall's designed alignment was altered to avoid an existing high pressure gas line. This gas line was potholed in advance of the slurry wall construction and found to be more than nine feet deep. The gas line surfaced and ran above grade to an existing block valve assembly 230 feet north of the intended slurry wall alignment. A directive was given to alter the original slurry wall alignment to the north approximately 230 feet so that the slurry wall would cross the high pressure gas line where the line was above grade. This jog in the slurry wall alignment can be seen at Station 37+50 to 43+00 on Plate 1. The slurry wall alignment returned to its original proposed alignment to the west of the gas line. Likewise, because the pipeline crosses through the entire site, it was crossed again at the opposite side of the property. Excavators were required to trench below and around the pipeline as the designed slurry wall alignment crosses its location along the north side of the site. This northern crossing of the gas line occurred at Station 78+25 and no change in slurry wall alignment was required. The gas line was five feet deep at this crossing. A change in the proposed slurry wall alignment was required to avoid an existing silt pond utilized by the aggregate mining operations. This silt pond had highly saturated, low strength, unconsolidated silts up to 75 feet in depth. To avoid potential trench failure, the slurry wall alignment was re-routed south and east of this pond (Station 57+00 to 67+00). Overburden soils stockpiled on the site were used to construct a working platform for the re-aligned portion of the slurry wall. The final alignment ~' is shown on Plate 1. From Station 66+00 to 73+00, the slurry wall traverses an area which had been stripped of overburden during mining operations. Fines content in the slurry wall backfill was found to be in the low end of the acceptable range in this area. Aker slurry trench backfilling operations were completed, the construction area was regraded and a cap constructed over the slurry wall. Along the northwest corner of the site, the bedrock exhibited a high sand content. The bedrock key depth was extended from three feet to up to five feet in this area. Highwall configuration and reservoir side slope stability will continue to require consideration as mining activities continue. Mining operations should not be allowed within 25 feet of the slurry wall. Unmined sand and gravel along the slurry wall interior provides the major stabilizing force counteracting the outside hydrostatic forces prior to placement of the reservoir slope backfill. To L prevent highwall stuffs and slurry wall damage, the reservoir slope should be reclaimed to at least a 3:1 (horizontal to vertical) slope along the highwall as soon as possible. In order to prevent slope -5-