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anion is sulfide. The pH is generally around 8. 2. The concentrations of major cations, total <br /> dissolved solids and nitrate (possible due to agricultural return flow)increase during periods of <br /> low flow(base flow). Total suspended solids (TSS) are higher downstream than upstream of the <br /> Loadout, with average values of 2,439 and 3, 175 milligrams per liter(mg/1), respectively. <br /> Section B, Item III of this document includes a discussion of the probable hydrologic <br /> consequences (PHC) of the Loadout on surface water quantity and quality and a discussion of the <br /> surface water monitoring plan. Alluvial valley floors (AVF's) are discussed in Section B, Item <br /> XIV of this document. <br /> Ground Water <br /> Ground water information is located in Tabs 7, 13, 14, and 15 of the PAP. A summary of this <br /> information can be found in Section B, Item III of this document, along with specific findings <br /> related to ground water hydrology. <br /> The reclaimed coal storage and tipple area of the Loadout was situated on alluvial and colluvial <br /> materials overlying the Lewis shale. Waters from the Lewis shale are a primarily calcium and <br /> sodium bicarbonate type although sulfate type water also occurs in the Lewis shale. The potential <br /> source of sulfates is the reduction of sulfide materials and organic materials in shales. <br /> The Lewis shale has low hydraulic conductivity. It is generally considered to be an aquitard that <br /> retards transmission of surface water to the underlying regional aquifer, the Twentymile <br /> Sandstone. This low conductivity results in low well yields which, along with poor water quality <br /> characteristics, preclude the use of Lewis shale waters for use other than stock watering (Seneca <br /> II -W Permit Application, HGTI application Attachment 7- 1). <br /> The alluvial material also has relatively low hydraulic conductivity (approximately 0. 1 to 0. 01 <br /> feet/day) due to its high composition of silts and clays. These alluvial waters are of poor quality <br /> due to the proximity of the Lewis shale, contributions from agriculture, and the ephemeral nature <br /> of Dry Creek(although the applicant reports that water is taken from Dry Creek bellow the <br /> Loadout and used for irrigation). <br /> Section B, Item III of this document includes a discussion of the PHC of the Loadout and the <br /> railway loop on ground water quality and quantity and a further discussion of the ground water <br /> monitoring plan. <br /> Climate <br /> The region is characterized by a semi -arid steppe climatic regime with cold winters and mild to <br /> cool summers. The prevailing wind is from the northwest(reversing at night due to southeasterly <br /> upslope winds). Average annual precipitation is 16 inches and the growing season in the region <br /> is approximately 94 days. Climatic information was collected from the Hayden <br /> Station, one mile away, and the Seneca II-W Mine, six miles south of the Loadout. <br /> More detailed climatic information can be found in Tab 8 of the PAP. <br /> 6 <br />