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<br />' Ssn Luis Project - Phase n Raise t t?xpenaion Cotuwction Statue Report <br />' The following sections describe the various field engineering decisions which have occurred <br />during expansion construction of the tailings area. Only field changes to the approved Permit <br />' Amendment and July 13, 1993 Phase II, Raise 1 Design Report are discussed. <br />4.2 Extent of Liner Placement <br />' The approved amendment discussed expansion of the disposal area in two phases associated with <br />' each embankment raise. <br />To reduce the disruption to operations which would be associated with two phases of liner <br />placement during Raise 1 and 2 construction and limit the seaming of liner sections, the Owner <br />has elected to line the entire ultimate impoundment area in a single liner campaFgn during Raise <br />1 construction. The ultimate azea to be lined is depicted on Figure C-6 in the Permit <br />Amendment, dated September 1989. This change was noted in the September 13, 1993 letter <br />from Alana Scott to Larry Oehler. <br />4.3 Subgrade Preparation - ~~` }' <br />1 <br />In azeas where the insitu soil will receive overlying fill materials, the soil is moisture <br />' conditioned to provide a damp workable material and compacted with 3-4 passes of a vibrating <br />sheepsfoot roller. Although no specification for compaction of this material was included in the <br />' original Earthwork Technical Specifications, compaction has and will continue to be adopted <br />during all construction. <br />' 4.4 Fill Materials <br />' Surveys for potential borrow sources for conswction fill materials were performed prior to the <br />initiation of work. In general, the available borrow sources consist of variable colluvial and <br />' alluvial soils which tend to change gradations with depth and spacial distribution. As a result <br />the search for suitable borrow materials is constantly ongoing. Source of silty sandy gravel is <br />also available from the open pit mining activities at the site. Previous material specifications <br />t used for construction of Phase I were tailored to the sources of borrow known to be available <br />at that time. It was anticipated during Phase I and in Phase II Raise 1, that within the limits of <br />prudent engineering, some modification of the specification for fill materials might be required <br />based on material avajlability. <br />' October, 1993 ti SRK Project No. 14725 <br />