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Third Party Oversight 19 Water, Waste & Land, Inc. <br />San Luis Mine January 10, 1993 <br />6.0 CONSTRUCTION OVERSIGHT AND QA TESTING <br />' 6.1 CONSTRUCTION OVERSIGHT <br />Construction field oversight work began on November 11, 1993 and concluded on <br />' December 8, 1993 when the embankment and tailings disposal facility expansion construction <br />was substantially completed. A registered professional engineer from WWL w:~s on site for <br />a majority of each construction day from November 17 through December 8, 1993. The <br />engineer generally observed and reviewed all phases of construction activities undertaken both <br />by BMRI and subcontractors including: <br />• construction techniques and material placement methods, <br />• borrow area excavations and general material types, <br />• QA sampling and testing including VLDPE welding, vacuum and destructive tests, <br />and fill material density, gradation and permeability tests, <br />• shift changes between the day and night crews to verify continuir~ of material <br />selection from the borrow areas and placement methods by the operators, <br />• QA test results conducted both on-sight and off-sight, and <br />• technical submittals. <br />1 <br />Daily field logs were completed by the engineer. Copies of the logs a-e located in <br />Appendix A. <br />Several occasions arose during construction when materials or construction techniques <br />' being employed may have created some concern with the DMG. Examples inc ude isolated <br />areas where drain spacing was greater than the specified 40 feet and isolated truckloads of <br />' embankment fill containing significant quantities of oversized materials. As these occurrences <br />were infrequent, the engineer decided not to immediately contact the DMG, but did note any <br />t potential problems in the daily field logs and in the weekly reports to the DMG, and also <br />brought the materials/techniques to the attention of the field QA personnel in a timely matter. <br />This allowed on-site QA personnel to verify materials/techniques before additional construction <br />activities covered the areas in question. <br />6.2 QUALITY ASSURANCE TESTING <br />In general, QA test results provided to date appear to be adequate anc valid. This <br />includes results from tests conducted before and after third-party oversight Table 6.1 <br />provides a summary of the frequency of QA tests conducted on construction materials as of <br />November 23, 1993 (BMRI, 1993r). <br /> <br /> <br />