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<br />Memo to Cathy Begej - 2 - March 13, 1990 <br />The contention by KCC that the possible high SAR overburden materials will not <br />be impacted by mining is completely false. One has to just look at Maps 12a <br />and 13a (Geologic Cross Sections F and G, respectively) and note the dip of <br />the rock beds to know that the mine pit will indeed intersect those possibly <br />high SAR strata. <br />In the interest of having meaningful baseline information so proper planning <br />of sodic overburden placement can be done, the following questions and <br />comments should be directed to KCC: <br />1. KCC must commit to drilling and sampling the overburden in the Pit 2 area <br />prior to mining. The sampling should be done in such a way as to <br />intercept the suspect zones as identified by overburden analyses of <br />samples from drillholes 028-80-28C (100-200 feet section) and 028-80-23C <br />(200-318 feet section). The drillnole placement and physical and <br />chemical analyses should be chosen in consultation with Division <br />personnel as required by Rule 2.04.6(2)(o)(ii). If the sampling <br />indicates acid-forming, toxic forming, or alkalinity-producing materials <br />then KCC should commit to developing a plan to selectively handle these <br />materials to ensure that they do not contaminate the groundwater or end <br />up with less tnan four feet of non-toxic surface cover. Such sampling <br />and handling plans must be completed prior to any further mining or <br />development in the Pit 2 area. <br />2. Since the same possibly sodic overburden was encountered in the Pit 1 <br />area by Drillhole 028-80-23C, KCC should immediately begin an overburden <br />sampling program for materials removed from the strata in question. <br />Additionally, KCC should sample overburden backfilled into the 720 Pit <br />and develop a mitigation plan for the 720 Pit which ensures that sodic <br />material will be kept above the postmining groundwater surface and at <br />least four feet below the final reclaimed surface. <br />Exchangable Sodium Percentage (ESP) Values - Pit 2 A <br />The ESP values given on the Overburden Analysis Forms were supposed to have <br />been obtained by using SAR values. KCC claims that ESP values were derived by <br />use of a correlation graph from Diagnosis and Improvement of Saline and Alkali <br />Soils (USDA Handbook 60 ). When I use the nomograph that I believe they would <br />use for tnis purpose (Figure 27 - Page 103) my derived ESP values do not even <br />come close to the ones on the analysis forms. The only conclusion I can come <br />to at this point is that the ESP values were calculated by using raw data that <br />the Division does not have. <br />KGC states that ..the Wyoming and Montana guidelines utilized by the ML RD in <br />suitability determinations...do not contain criteria with respect to LESP]." <br />KCC should know that ML RD presently does not have guidelines for suitab ility <br />with respect to soils and overburden. <br />KCC also states that all high ESP values were in samples located outside the <br />Pii 2 area. While this is technically true, the high ESP value samples were <br />in strata that would be intercepted by the mine pit. <br />