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<br />Creek, two under Stewart Gulch, and two under Parachute Creek. The pipelines <br />• would be placed at least 3 feet below the bottom of each of these drainages. In <br />addition, the entire length of both pipelines will be buried to a depth of about 3 feet, <br />well below the frost line. Both pipelines will be constructed of steel. Thus, there is <br />little potential for a pipeline breach to occur except under an extreme seismic event, <br />and the project area is in an area of low seismicity. The final design of the pipeline <br />will include appropriate consideration of regional seismicity. In addition to steel <br />core construction, the product pipeline, which contains the higher concentrations of <br />sodium carbonate/sodium bicarbonate, will have three layers of insulation, <br />including fusion-bonded epoxy, closed-cell polyurethane foam, and an outer layer of <br />high-density polyethylene. This construction and a burial depth of 3 feet will <br />minimize the potential for large quantities of fluid to escape into surface waters <br />even if a breach were to occur. A description of the methods used to lay the pipes is <br />given in Section 2.2.3. <br />Prevention of impacts to surface waters due to excessive runoff from well pads and <br />other well field features will be accomplished by employing best management <br />practices for erosion control, including water bars, sediment barriers, and mulch <br />applications, as appropriate (see Section b.b). All disturbed sites within the well field <br />will be stabilized using suitable techniques, e.g., mulching or annual vegetation) to <br />prevent erosion until perennial vegetation has become established and reclamation <br />is complete. Final reclamation and revegetation of mining panels will be initiated <br />• as soon as is reasonably practicable. <br />Site protection plans will be developed, as appropriate, for both sites to minimize <br />the potential for adverse impacts resulting from any discharges to adjacent surface <br />water drainages (see Section 5.0). An evaporation pond associated with the <br />Parachute Site processing facilities will be used to hold wastes from the cooling <br />tower and boiler and discharge from the process water treatment plant. <br />Approximately 31 gpm of wastes from these sources will enter the evaporation pond <br />(Kvaerner 1998f). The pond will be lined to prevent seepage, and no discharge from <br />the pond is anticipated. The evaporation pond is isolated from natural drainages <br />and will be designed to accommodate the 100-year precipitation event. As a result, <br />the evaporation pond is unlikely to be vulnerable to overtoppping or dam failure <br />due to flooding. No adverse impacts to surface waters from use of the evaporation <br />pond are anticipated. <br />8.3 GROUNDWATER <br />As discussed in Section 8.2, it is anticipated that water for the Yankee Gulch Project <br />would be provided by water taken from the Colorado River under an existing <br />surface water right. The water right may also allow water to be withdrawn from <br />existing water wells in the Parachute Creek drainage. Use of existing water rights <br />would eliminate any new depletion of groundwater as a result of commercial <br />• operation of the Yankee Gulch Project. <br />American Soda, L.L.P. 8_10 <br />Commercial Mine Plan <br />Augusl IR. 1998 <br />