REP37807

• Permit No: M1988112
• IBM Index Class Name: Report
• Doc Date: 5/17/1994
• Doc Name: SAN LUIS PROJECT TAILIGNS DISPOSAL AREA PHASE II RAISE 1 FINAL CONSTRUCTION REPORT
• Media Type: D
• Archive: No

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San Luis Project Phase U Raise 1 8xpanaion -Final Conawction Report
frequency was increased in an attempt to delineate areas which do not meet the specification. The
azeas identified as containing out of specification material were infrequent and relatively small in
areal extent (tb acre maximum). A conservatively estimated total of approximately 0.75 acres out
of the 23 acres of drainage blanket material placed prior to use of the screening plant may not meet
the specifications. These areas contain some material which was out of specification with regard
to the allowable percent passing the No. 200 sieve (fines).
On November 19, 1993, the Division verbally approved the placement of embankment fill material
over 0.17 acres of suspected out of specification drainage blanket material located at the south of
the embankment abutment. BMRI followed the verbal approval from the Division with a
confirmation letter to the Division on November 24, 1993. The drainage blanket material in this
area would never be in contact with tailings since the embankment covers that area. Of the
remaining material which may be out of specification, 0.12 acres is located at or above the
maximum tailings elevation within the required freeboard. Therefore, an estimated 0.46 acres of
drainage blanket material that will be in contact with tailings may not meet specifications; this
represents approximately 0.8 percent of the Phase II expansion area. The maximum thickness of
tailings to be placed over any area containing out of specification material is 20 feet with 0.12 acres
of the 0.46 acres having a maximum tailings thickness of less than 10 feet.
The azeas of drainage blanket material which are suspected to be out of specification typically
contain some material which has 35-40 percent fines (the maximum specified is 35 percent) which
is primarily a result of their relative deficiency in the coazser fractions. With a small increase in
the coazse fraction (5-10 percent) these materials would meet the specifications, hmwever, this would
have little or no actual effect on the material permeability. As the permeability of the drainage
blanket is the primary issue with regazd to the function of this layer, laboratory permeability testing
of samples of the out of specification material prepared at field densities was conducted. The results
of these tests aze presented in Table 1.