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Knight Piesold <br /> CONSULTING <br /> The SPLP test(EPA method 1312) is conducted to approximate metal leaching when a material is exposed <br /> to rainwater. Similar to the TCLP, the SPLP uses a 1:20 mix of solids with water and an 18-hour agitation <br /> period. The pH of the water is adjusted to simulate rainwater pH (approximately 5 for the area west of the <br /> Mississippi). Following the agitation period, the residual solution is analyzed for pH, electrical conductivity, <br /> hardness, metals, and major cations and anions. Laboratory data is included in Attachment 1. <br /> : .0 DISCUSSION OF RESULTS <br /> The ABA test results are shown in Table 1. Results of the ABA testing indicate the materials tested are <br /> slightly acid generating as evidenced by the low paste pH, which ranges from 4.41 to 4.74. However, the <br /> long-term acid generating potential of the materials is considered low to very low due to the low sulfide- <br /> sulfur content(0.05 to 0.06 weight percent[wt%]sulfide-S). Generally, materials with a sulfide-sulfur content <br /> of less than 0.1 wt% sulfide-S are considered non-acid generating (GARD Guide, 2014). The low paste pH <br /> is likely a result of residual sulfosalt minerals that have slight excess acidity that is evidenced by the high <br /> sulfate soluble sulfur(Table 1). <br /> Table 1 ABA Results <br /> Sample ID Paste Total Sulfate-S Sulfide-S Insoluble S AGP NP NNP <br /> pH S (by dill.) <br /> pH Kg Kg Kg <br /> Units Units °70 % % % CaCO3/T CaCO31T CaCO3fT <br /> SGLLC W-1 4.41 0.44 0.23 0.09 0.12 2.8 0.7 -2.10 <br /> SGLLC C-1 4.74 0.22 0.15 0.05 0.02 1.6 1.0 -0.60 <br /> SGLLC E-1 4.72 0.28 0.18 0.05 0.05 1.6 1.5 -0.10 <br /> The TCLP tests indicate that none of the materials tested can be considered hazardous waste (Table 2). <br /> All of the tests indicate low leachability of the TCLP metals compared to the standards. With the exception <br /> of barium, lead, and zinc, metals leaching was below detection limits. <br /> Table 2 TCLP Results <br /> Sample ID Arsenic Barium Cadmium Chromium Lead Mercury Selenium Zinc <br /> Units m /L m /L m /L m /L m /L m /L m /L m /L <br /> TCLP Limits 5 10 1 5 5 0.2 1 5 <br /> SGLLC W-1 <0.10 0.24 <0.10 <0.10 0.75 <0.002 <0.10 0.31 <br /> SGLLC C-1 <0.10 0.12 <0.10 <0.10 0.49 <0.002 <0.10 0.27 <br /> SGLLC E-1 <0.10 0.16 <0.10 <0A0 2.34 <0.002 <0.10 0.43 <br /> The SPLP results were compared to the instream water quality standards for Clear Creek for Segment 2B <br /> as defined by the Colorado Water Quality Control Commission (WQCC). The WQCC established water <br /> quality standards that are protective of the beneficial use of each stream segment. Segment 2 defined <br /> beneficial use is for water supply, agriculture, aquatic life (cold), and recreation. The standards used for <br /> comparison to the SPLP leachates are either referred to as table value standards (TVS) established by the <br /> WQCC in Regulation 37 (WQCC, 2020) or listed in Regulation 38 (WQCC, 2018) (Attachment 2). The TVS <br /> standards are calculated based on hardness. Only those constituents that exceeded the water quality <br /> standards are shown in Table 3. The full data set is included as Attachment 1. It is notable that this reach <br /> of Clear Creek has been determined by the WQCC to be impaired with respect to cadmium and zinc(Clear <br /> January 14,2021 <br /> DV-21-0024 4 of 6 <br />