GENERAL46097 - Laserfiche WebLink

Home Browse Search

Water quality constituents of concern to the AVF identified on Fish Creek include trace metals, sulfate, and TDS. An evaluation of concentration levels present in the mine dischazge indicate TDS to be the constituenC most likely to place a restriction on the quality of irrigation water. Rule 2.06.8(5)(b) identifies material damage as increases in electroconductivity to levels above a threshold value at which crop yields decrease. The relationship between electroconductivity and TDS has been demonstrated level by Seneca Coal Company, in the permit application. The operator has submitted an analysis based on amass-balance loading of TDS in Fish Creek. Concentrations of TDS in mine effluent were the maximum values from Spoils Spring Number 1 in the Cow Camp Creek drainage. Mean flow values for June and July were used for Cow Camp Creek, Bond Creek, and an upstream location on Fish Creek in the calculations. Results indicated significant dilution would take place and maximum expected TDS concentrations of 607 mg/I were expected in Fish Creek below the mine. The maximum TDS level projected would correspond to a conductivity of less than 1 mmho/cm. A conservative estimate of the relationship between imgation water salinity and root zone soil salinity, as referenced in USDA Handbook 60, is 1 to 1.5, respectively. Thus, irrigation water applied with a specific conductance of 1 mmho/cm would result in root zone soil water with a specific conductance of 1.5 mmho/cm. No decrease in production of any of the species identified in data submitted by the operator would be expected unless the conductivity of the irrigation water were to exceed 1 mmho/cm. No significant decreases in productivity would occur unless root zone soil water salinity were to exceed 1.5 mmho/cm. Given the limited effect of Seneca II Mine dischazge on Fish Creek surface water quality, it is deduced that alluvial ground water quality should not be significantly impaired. Recharge of the Fish Creek_alluvium from the_Cow Camp and Bond Creek-tributazies would be expected to be minimal compared to upstream contributions. Sub-imgation would be expected to be less affected by mine dischazge than irrigation using surface waters. A conservative estimate of the expected effect of mining indicates that no material damage would result. AVF Findin¢s The Division has determined that an alluvial valley floor exists within the affected or adjacent azea. Therefore, the following fmdings aze in order for the alluvial valley floors known as Fish Creek, Grassy Creek and Little Grassy Creek. Fish Creek; The Division fmds that activities proposed by the applicant will not interrupt, discontinue, or preclude farming on the alluvial valley floors that aze imgated or naturally sub-irrigated. (4.24.3(1)). 40