Laserfiche WebLink
1. <br />• I( <br />SUMMARY ANO CONCLUSIONS <br />1~ Data, analyses, and conclusions of a hydrologic investigation in the <br />vicinity of CFSI Steel Corporation's Allen and Maxwell Mines are presented <br />] 1n this report. These mines are underground coal mines located in Las Animas <br />County on the Purgatoire River approximately 30 miles west of Trinidad, <br />~l Colorado. The study included characterization of the hydraulic properties <br />of the coal seam, overburden, and alluvium by field and laboratory tests. <br />f~ A combination of drill holes and backhae pits were used to investigate the <br />distribution of alluvium and terrace materials in the vicinity of the Maxweli <br />--~ Mine. Estimates of eventual inflows to the Maxwell Mine were made and these <br />~: were coupled with water quality data on mine and stream discharges to calcu- <br />~ late the expected effect of mining on the quality of waters in the Purgatoire <br />,, > River. A water balance was used to estimatg the deep percolation from the <br />active refuse pile at'the Allen Mine. The chemical characteristics of the <br />I supsurface discharge from the refuse pile were determined and the influence <br />of the waste material~on the quality of stream waters was estimated. <br />• _ Oata_from_ this imLestigation~studies by others,_and from.the_ALlen <br />Mine indicate a-very_low._water_-bearinq.capacit~of_strata in the Raton forma- <br />l - --- .--- ----- <br />Lion. , <br />~- <br />7 - The ground_water~inflows td the Maxwell Mine are expected to be on the <br />orde^ r of 180 gpm at full mine development. The source of this discharge <br />is the coal seam and vertical flow through the overburden in response to <br />the drawdown caused by the mine. This estimate of inflow is consistent with <br />the inflow now being observed in both the Maxwell and Allen Mines. Using a <br />conservatively estimated value for mean low flow in the Purgatoire River, <br />- .r <br />> discharge_of this inflow will cause an estimated increase of dissolved solids <br />in the_stream equal to 47 mo/i_ The increase in the average dissolved <br />solids concentration in the mean annual flow at the Maxwell nine location <br />--- ~ wtil~6e about-13 mg/1. Estimated. changes in trace element concentrations <br />-~ are very small. Simiiar conclusions were reached relative to the effect of <br />._.----- <br />current mine discharge from the Alien, the estimated increase in dissolved <br />I solids being 32 mg/1. It is estimated that the combined contribution of the <br />1 current_Maxwell anil A11en discharges and_ the_ ac_tiv_e__refuse-Di.le~t_Lhe~ll.len <br />~~~ --~ to the total salt pickup between Stonewall and Madrid is about 2~ercent. <br />