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i • <br />ilattle Mountain Resources, Inc. <br />Mr. Bill Lyle <br />January 29, 2000 <br />Page 2 of 4 <br />A) Pre-Treatment <br />The pre-treatment train consists oflime-soda ash water softening, pH adjustment, <br />and pre-reverse osmosis (RO) membrane separation . <br />B) RO Units <br />The main components of the treatment system aze two 200-gpm RO modules that <br />contain 144 X00 square foot membrane units. <br />C) Post Treatment <br />The post-treatment system consists of pH adjustment before discharge. <br />D) RO By-Product Water Treatmeut <br />The reject concentrate water from the RO units is treated using quick lime to <br />precipitate sulfate (S04) in a form of gypsum. This treated water is then passed <br />through a series of clarifiers to remove the gypsum as sludge. Acentrifuge- <br />dewateringsystem is used to de-water the sludge. The solid portion of the sludge is <br />fwther dried at a contained unit and is subsequently transported to an ofl=site <br />facility for disposal. A sludge analysis conducted on representative samples <br />identifies that the generated sludge passes the TCLP analysis. The water from the <br />clarifiers and centrifuge is mixed with influent water that returns to the treatment <br />plant. <br />Cost Estimation <br />The purpose of this cost analysis is to determine the Operation and Maintenance (Ct&M) cost <br />associated with treating recovered groundwater at the subject site over the operational life of <br />the treatment plant. ERNW has used fast hand knowledge of the temporary systems O&M <br />costs and the design knowledge ofthe permanent system to develop this analysis. ']~he <br />permanent treatment plant is designed to handle a throughput of up to 900 gpm with an output <br />of up to 450 gpm. Because of the remote location, ERNW has included various system <br />redundancies to deliver a 400-gpm output during the first yeaz of operation. After the first year <br />of operation and achieving steady state groundwater recovery, the estimated plant throughput <br />is estimated at I50 to 180 gpm, but maintains the capacity to manage and treat the 450 gpm <br />design capacity. <br />The redundancies that have been designed into the treatment plant will extend it's anticipated <br />life span by a factor of two. This will reduce system component failure and reduce severe <br />wear and teaz generally experienced by a 24-hour plant operation of this type. In addition, <br />because of the extra capacity, the system operator can bypass to other units while the staff <br />maintains the off-line treatment unit. <br />