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<br />' San Luu Project - Phase ^ Rsiae 1 Expansion Corotnxtion Statue Report <br />b.7.4 Solution Collection Ditches <br />' Covering the portions of the 40-mil. VLDPE liner which are exposed in the solution collection <br />ditches located downstream from the embankment will provide additional protection to the liner <br />in this azea and reduce the potential for liner damage in these areas. <br />7.0 CONCLUSIONS <br />The field engineering changes which have been implemented during the construction of the Phase <br />II, Raise 1 embankment and disposal azea expansion do not alter the tfesign intent or <br />' performance of the tailings disposal area and are consistent with sound $eld engineering <br />judgement. These changes have been implemented to facilitate construction and match or <br />' improve the design and specifications to actual field conditions encountered during the <br />construction, <br />' The Division's concerns over the suitability of the liner cover material are shared by BMRI and <br />the design engineer. Although a portion of the liner cover material has been placed by the <br />' earthwork contractor, it has not been accepted by the design engineer's field representative's <br />final inspection. Testing of the in-place liner cover material is ongoing and if the in-place <br />material does not meet the gradation specifications, this material will be blended or removed to <br />' meet the specifications. <br />Although not required to complete permeability testing of the liner cover material in any <br />' approved permit document, the design engineer has completed permeability testing of the liner <br />cover material to verify that the material is more permeable than the tailings and will, therefore, <br />' promote drainage from the tailings. In addition, calculations relating to head and potential <br />seepage rates from the liner system demonstrate that the system will perform better than <br />expected and limit the seepage potential to less than the original predictions. At the request of <br />' the Division, additional test work will also include an evaluation of any consistent zoned <br />variability in the gradations of the entire liner cover material profile which could act to prohibit <br />water movement. <br />Field engineering changes to the material specifications for the material for the embankment <br />' raise construction will not alter the intent of the design or the performance of the thin layer <br />deposition in the tailings disposal azea. The material used for the embankment raise is similaz <br />' to the material used on the upstream face of the initial embankment raise. The evaluation of <br />CPT data presented in the Phase II, Raise 1 Design Report of the tailings dewatering which <br />October, 1993 ~ SRK Rojcd No. 14725 <br />