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Attachment A <br />Discussion <br />There are two basic approaches to address water quality impacts from the forrrter oil shale <br />retort. First, attempting to prevent groundwater from coming in contact with the former <br />retort area, by various means; and second, treating or disposing of water that has come in <br />contact with the former retort area. OOSI had previously considered actions for <br />decontamination of the retorts and has also taken actions to reduce water from contacting <br />the spent shale in the retorts. These actions are discussed below. <br />The evaluation of the potential treatment of retort discharge water obviously involves the <br />consideration of contaminants of concern in the water and what treatment technologies <br />maybe available that may successfully treat the discharge water. OOSI has collected <br />water quality data for the retort discharge periodically over the last several years at <br />various locations along the discharge piping system. Retort water has been collected at <br />the Lower Bench Vault, located approximately 100 ft from the sealed L-1 Portal; the <br />Upper Manhole, located approximately 3,800 ftdown-pipe of the L-1 Portal; and the <br />Lower Manhole, located approximately 5.5 miles down-pipe of the L-1 Portal neaz the <br />Evaporation Pond. <br />Generally, these data (Table 1 in this document and Table 2 of Exhibit G) show that <br />contaminants of concern include the organic compounds of benzene, toluene, <br />ethylbenzene, and xylene (BTEX), total petroleum hydrocarbons (TPH), oil and grease, <br />and phenolics and inorganic compounds such as boron, calcium, chloride, fluoride, <br />potassium, sodium, and sulfate. The BTEX compounds have been detected in <br />concentrations below state groundwater standards at the Lower Bench Vault, but have not <br />been detected at the Lower Manhole location. Of the inorganic compounds, boron and <br />fluoride have exceeded the agricultural groundwater standards and sulfate contributes the <br />most to total dissolved solids (TDS) with concentrations between 3,500 and 4,000 mg/L. <br />fiDS ranges as high as 6,600 mg/L. The presence of large concentrations of inorganic <br />solutes such as sulfate and TDS in general, are of high importance since passive <br />treatment of these parameters is considered difficult. <br />The data in Table 1 do not show a perceptible trend towazds better water quality with <br />time, and under current discharge conditions, the retort water will likely not meet <br />applicable surface water or groundwater standards within 5 years. <br />As shown in Table 1, Exhibit G of the amendment, the average measured dischazge of <br />retort water is 4.8 gallons per minute (gpm). This average is affected by higher flows that <br />resulted after retorts were shut-in for repairs. Retort dischazge has typically ranged <br />between 2.5 and 3.0 gpm in the last two years. OOSI is currently sampling the retort <br />discharge on an annual basis. <br />In 1999, OOSI submitted a Retort Closure Plan (Technical Revision No. 1) whereby it <br />was proposed to shut-in the retort bulkheads and allow head in the retorts to recover to <br />ambient groundwater levels and natural hydraulic gradients. DRMS accepted this plan <br />and it was implemented on February 8'", 2000. However, several months later <br />4 <br />