Laserfiche WebLink
• <br />Memo to Larrv Oehler 3 May 5, 1994 <br />lost, the drainage layer will be flooded, and a hydrostatic head <br />equal to the thickness of the tailing will be applied to the <br />liner. Utilizing inputs to the above formula found in Figure 3 of <br />the January 1994 report prepared by water, waste and Land (WWL), <br />and giving the facility the benefit of the doubt in regard to each <br />input within the constraints discussed in the WWL report, yields <br />the following result: <br />h= 40 2x10_b <br />2 9x10-5 <br />h = 4.47 feet <br />Analyzing for the worst case scenario from the inputs available in <br />the WWL Figure 3 yields: <br />h= 40 9x10_6 <br />2 2x10-5 <br />h = 8.94 feet <br />IN EITHER CASE THE DESIGN HYDRAULIC BREAK IS LOST <br />The foregoing analysis is based upon testing results for the Phase II <br />drainage blanket, whereas most of the drainage blanket under the free <br />water pond would be part of the Phase I installation. However, since <br />there is no legitimate permeability data for the Phase I drainage <br />layer, this analysis represents the best information available. <br />The Division can conclude from this analysis that there is a <br />significant probability that extreme hydrostatic head is being applied <br />to the liner beneath the free water pond in both the up~er and lower <br />impoundment areas, with a resultant exponential increase n the rate of <br />seepage through the liners in these areas. The analyses aan be refined <br />based upon the receipt of additional permeability data for the drainage <br />blanket and the tailing, and seepage rates can be estimated for the <br />impoundment below the free water ponds utilizing the soil liner <br />permeabilities currently available, as well as those data on soil liner <br />permeability to be provided by BMRI based on laboratory tests. These <br />seepage rates could then be used to estimate the potential or degree of <br />saturated flow toward the water table that may be induced below the <br />tailing facility if the specific retention of the soils beneath the <br />impoundment are exceeded. <br />BMRI will likely argue that initial tailing deposition into the San <br />Luis facility resulted in an extremely low permeability layer of tails <br />