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<br />Letter to Alana Scott 2 December 23 1993 <br />specified in the November 2, 1993 letter from Larry Oehler to Ken <br />Kluksdahl. The reasons for that requirement are as follows: <br />1. Installation of tailings piezometers was a requirement <br />incorporated into Permit No. M-88-112 by approval of the 1989 <br />amendment to the permit (response nos. 15 & 29, Permit <br />Amendment Adequacy Responses, 1/9/90). The momentum generated <br />by BMRI's failure to instal the required tailing piiezometers <br />during construction of the main embankment will not be allowed <br />to carry over to the tailings piezometers required for Phase <br />II, Raise 1. <br />Tailings piezometers at Raise 1 were an independent <br />recommendation made by WWL during a meeting between WWL and <br />the Division on 11/2/93. WWL is a third party technical <br />oversight engineer accepted by both the Division and BMRI; WWL <br />confirmed their continued support for installation of tailings <br />piezometers during a phone conversation on 12/22/93 (verbal <br />communication, Clint Strachen, WWL). <br />3. BMRI has requested, and received approval of, a specification <br />change to use a material with greater fines content to <br />construct Raise 1. One of the issues that has been involved <br />with utilization of the material with greater fines content, <br />has been the potential impact on drainage and desiccation of <br />beach tailing that will form the foundation for Raise 2. <br />Tailings piezometers will provide continuous information on <br />the ability of the tailings to drain during the filling of <br />Phase II. The Raise 2 lift foundation investigation (which <br />will continue to be a requirement regardless of tailings <br />piezometers) will provide only one time, or snap-shot <br />information on the state of drainage. An advantage to <br />continuous information on the state of drainage wound be lead <br />time provided for planning of Raise 2 if unforseen drainage <br />problems develop. BMRI has indicated that downstream or <br />centerline raises would be constructed in the event that the <br />tailings materials are not suitable for construction of the <br />upstream raises (response no. 15, Permit Amendment Adequacy <br />Responses, 1/9/90). A change to downstream or centerline <br />raises would require an amendment to BMRI's permit which could <br />require considerable lead time. <br />BMRI has stated their belief that the tailings piezometers will not <br />provide meaningful data, particularly in terms of the source layers <br />for water collected by the piezometers. BMRI should be aware that <br />the Division is concerned with any degree of saturation in the <br />Raise 2 foundation area, regardless of the source layer location <br />and thickness, and believes that the tailings piezometers will <br />provide information on presence of saturation or development of a <br />phreatic surface that could have a bearing on the stability of <br />