REP19624

• Permit No: M1988112
• IBM Index Class Name: Report
• Doc Date: 5/15/1995
• Doc Name: SAN LUIS PROJECT
• From: WESTEC
• To: DMG
• Media Type: D
• Archive: No

Third Party Oversight 9 Weter, Waste & Land, Ine.
' San Luis Mine June 9, 1994
' 3.0 CONSTRUCTION OVERSIGHT AND QUALITY ASSURANCE TESlNNG
' 3.1 CONSTRUCTION OVERSIGHT
Construction field oversight work began on November 11, 1993 and concluded on
December 8, 1993 when the embankment and tailings disposal facility expansion construction
was substantially completed. A registered professional engineer from WWL was on site for
a majority of each construction day from November 17 through December 8, 1993. On-site
observation was scheduled to accommodate the two-shift per day construction schedule. The
engineer generally observed and reviewed all phases of construction activities undertaken both
by BMRI and subcontractors including:
^ Construction techniques and material placement methods,
^ Borrow area excavations and general material types,
^ QA sampling and testing including VLDPE welding, vacuum and destructive tests,
and fill material density, gradation and permeability tests,
' ^ Shift changes between the day and night crews to verify continuity of material
selection from the borrow areas and placement methods by the operators,
' ^ QA test results conducted both on-sight and off-sight, and
' ^ Technical submittals.
Daily field logs were completed by the engineer. Copies of the logs are located in
' Appendix A.
Several occasions arose during construction when materials or construction techniques
' being employed may have created some concern with the DMG. Examples include isolated
areas where drain spacing was greater than the specified 40 feet and isolated tnuckloads of
embankment fill containing significant quantities of oversized materials. As these pccurrences
were infrequent, the engineer decided not to immediately contact the DMG, but did note any
potential problems in the daily field logs and in the weekly reports to the DMG, and also
brought the materials/techniques to the attention of the field QA personnel in a timely matter.
This allowed on-site QA personnel to verify materials/techniques beforeadditional oonstruction
activities covered the areas in question.
3.2 QUALITY ASSURANCE TESTING
In general, QA test results provided appear to be adequate and valid. This includes
' results from tests conducted before and after third-party oversight. Table 3.1 provides a
summary of the frequency of QA tests conducted on construction materials based on the Final
Construction Report (SRK, 19941.