2008-04-15_REVISION - M1980244 (325)

Home Browse Search

16 Main project area hydrologic conditions 3.8 Squaw Gulch Current Conditions The Squaw Gulch drainage and the MLE permit boundary are shown on Figure 3.1. Squaw Gulch is asouthwest-oriented, ephemeral drainage that crosses the diatreme- granite boundary. Squaw Gulch drains into Cripple Creek approximately 4,700 feet southwest of where Highway 67 crosses the drainage. Historical mine features within the Squaw Gulch drainage include: historical and residual waste rock stored behind the Mary McKinney cribbing; spoils piles from old glory holes and adits located above Highway 67, historical mill tailings deposited in Squaw Gulch below Highway 67 and historic townsites of Anaconda and Mound City. The current Cresson Project disturbance in the drainage consists of the SGOSA. The SGOSA construction started in 1993. Rock placement in the SGOSA will continue through approximately 2014 under the proposed MLE. The MLE also proposes to extend the size and volume of the SGOSA to include the SGOSA extension. The limits of the SGOSA extension are shown on Figure 1.2. Surface Water Surface water conditions in Squaw Gulch are assessed at four locations between the stormwater sediment pond below the SGOSA and the confluence of the Squaw Gulch and Cripple Creek: SG-05, SG-06, SG-07, and SG-10. Sample stations are shown on Figure 3.1. The period of record, water quality statistics, streamflow data and field parameter data summaries have been compiled for the sample stations SG-05, SG-06, SG-07, and SG-10, and are provided in Tables A19 through A22 (Attachment A), respectively. Surface water flows in Squaw Gulch are seasonal and generally low (0 to 164 gpm). Flows, if observed, occur in the spring due to snowmelt runoff and/or in the summer due to seasonal rains and runoff. Flow rates, when multiple stations report flow, increase downstream. The surface waters in Squaw Gulch are characterized as calcium-sulfate waters. A piper plot (Figure 3.6) shows the major ion water chemistry for the Squaw Gulch drainage surface water stations. Data show that for samples collected in the same monitoring period (usually the same day), pH values increase downstream from 4.2 su (average) at SG-05 to 6.2 su (average) at SG-07. Nitrate values range from 0.61 to 5.8 mg/L. Sulfate values generally increase in the downstream direction from 285 (average) at SG-05 to 690 (average) at SG-10. Groundwater Groundwater conditions in Squaw Gulch are monitored via a network of three monitoring wells and one shallow piezometer (Figure 3.1). The monitoring wells are designated SGMW-3A (diatreme), SGMW-36 (alluvium/shallow diatreme), and SGMW-5 (granite). Monitoring wells with the "B" designation are generally shallow and are screened in the alluvium and the shallow bedrock. Monitoring wells with the "A" designation (or no suffix) are generally deeper and are screened in the bedrock. The shallow piezometer is 2736 Cripple Creek & Victor Gold Mining Company Water Management Consultants