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Page 2 June 29,2020 <br /> Total Petroleum Hydrocarbons (TPH, i.e., DRO and GRO), metals, chloride, nitrate, sulfate, semi- <br /> volatile organic compounds (SVOCs, acid compounds only), the volatile organic compounds (VOCs) <br /> benzene, toluene, ethylbenzene, and xylenes (BTEX), pH, salinity, electrical conductivity, pH, and <br /> sodium adsorption ratio(SAR). <br /> Figure 1 is a location map of the spill site. Table 1 summarizes the results of the soil sample analytical <br /> data along with Colorado Soil Evaluation Values (Soil Screening Levels), Groundwater Protection <br /> Levels,and soil background sample chemistry data for samples previously collected near the Evaporation <br /> Pond in 2018. The Colorado Soil Evaluation Values and Groundwater Protection Levels are published <br /> by the Colorado Department of Public Health and Environment Hazardous Materials and Waste <br /> Management Division (CDPHE HMWMD). Soil background samples are discussed in more detail in <br /> the letterreport of April 6,2018,titled:Logan Wash Mine Evaporation Pond—Soil Sampling Results. <br /> Photographs of the spill site immediately after and several days after the spill are in Attachment A.The <br /> complete laboratory analytical report for the soil analysis is in Attachment B. <br /> Findings <br /> Table 1 shows that of the inorganic parameters tested in both background and the spill-site sample(LW- <br /> Retort Spill 052620), the level or concentrations of the parameters of pH, calcium, and magnesium <br /> exceeded the range in the background samples.With the exception of arsenic,none of the concentrations <br /> of parameters tested in the spill-site sample exceeded Colorado Soil Evaluation Values. In addition, <br /> CDPHE uses an arsenic soil concentration threshold value of 11 mg/Kg (determined by a U.S. <br /> Environmental Protection Agency—Region 8 background survey of soils)to assess potentially impacted <br /> soils(CDPHE,2014). Soil sample LW-Retort Spill-052620 had a concentration of 8 mg/Kg. <br /> Arsenic(total)in retort water has ranged from 0.0192 to 630 µg/L,with an average of 13.56 µg/L in 31 <br /> samples collected since 2008 during semi-annual sampling at Logan Wash Mine.The state standard for <br /> arsenic in groundwater is 10 µg/L and 100 µg/L for drinking water supply and agriculture use, <br /> respectively.The state chronic standard for arsenic for aquatic life is 150µg/L. <br /> Of note, the spill-site sample showed undetectable results for selenium. This is unusual as selenium is <br /> prevalent in soils in western Colorado. <br /> The analytical results for organic constituents show undetectable concentrations of BTEX and SVOC <br /> compounds. Diesel Range Organic(DRO) compounds were detected at 8 mg/Kg and Gasoline Range <br /> Organic compounds(GRO)were not detected.DRO and GRO combined make up the total volatile and <br /> extractable petroleum hydrocarbons(TPH). The Colorado Division of Oil and Public Safety(OPS)has <br /> established a threshold value of 500 mg/Kg for TPH,at which further analytical testing should occur for <br /> poly-nuclear aromatic hydrocarbons (PAHs). The Colorado Oil and Gas Conservation Commission <br /> (COGCC)also uses the threshold of 500 mg/Kg for TPH. <br /> The parameters of electrical conductivity, salinity,and SAR were within the range for background soils <br /> samples collected in the area. <br /> Conclusions and Recommendations <br /> It is evident from the presented data above,that the spilled retort water has not significantly impacted the <br /> wetted soils in the bar ditch. While pH, calcium, and magnesium exceeded their background ranges, <br /> these constituents in soils can vary dramatically by soil type and they do not present a significant health <br /> risk(no state standards exist for calcium and magnesium in the soil screening levels or groundwater).If <br /> these constituents are the result of retort water impact,it is expected that they will attenuate with time as <br /> AYe1de11_SHa11062920.doc <br />