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Groundwater Quality Monitoring Plan <br /> 90 <br /> • Trichlorophenol - used in the manufacture of herbicides, primarily <br /> 2,4,5-TP (Silvex) which has been banned in the United States for <br /> decades. <br /> • Tetrachlorophenol -used as a preservative. <br /> • Pentachlorophenol (PCP) - used as an antimicrobial wood preservative <br /> and historically coating on utility poles and cross arms. PCP is often <br /> mixed with creosote or other wood coating products. The US EPA is <br /> phasing out the uses of PCP over five years beginning in 2022. Wood <br /> treatment facilities will be allowed to use their existing stocks of PCP <br /> for wood treatment until 2027. Due to the high toxicity of PCP, it is <br /> normally used for toxicity calculations for chlorophenols. <br /> Phenol is similar to chlorophenol and is an important industrial chemical used <br /> as a precursor to many different materials and useful compounds. Phenol is <br /> readily soluble in water and sources of it in groundwater would be limited to <br /> industrial facilities. In general, chlorophenols and phenol are considered a <br /> problem in drinking water systems because they have a strong pungent odor in <br /> very small concentrations. The odor makes the water undesirable to drink <br /> regardless of the risk factors associated with toxicity. <br /> Chlorophenol As stated in Reg 41 —Basic Standards for Groundwater (page 56) "The organic <br /> and chemicals chlorophenol and phenol were moved from Table 1 (Human Health <br /> Phenols(cont.) Standards)to Table 2 (Secondary Drinking Water Standards), and the proposed <br /> standards were set equal to the Ambient Water Quality Criteria for the <br /> chemicals.The reason for the change is that although the two chemicals pose a <br /> significant health risk at much higher concentrations, taste and odor <br /> considerations are a concern at lower concentrations." <br /> Chlorophenols and phenols are not associated with sand and gravel mining and <br /> may only be a concern if the mining site were adjacent to a wood treatment <br /> facility. Broderick Wood Products (BWP) Superfund site in Denver and is <br /> adjacent to the Koppers Wood Treatment facility. Both sites have been studied <br /> extensively and groundwater contamination was identified off-site and in the <br /> neighborhood. Molen & Associates has collected groundwater monitoring <br /> samples at the BWP site. Reports generated for the EPA demonstrate that the <br /> PCP concentrations are below the detection limits in many of the on-site and <br /> off-site wells.The reported concentrations indicate that even at a facility where <br /> PCP was used,the concentrations in groundwater are too low to be detected by <br /> standard analytical equipment with a detection limit of 1 microgram/liter. <br /> Reg 41 — Basic Standards for Groundwater generally considers chlorophenols <br /> and phenols as a pollutant of concern due to the odors and taste in drinking <br /> water, and if PCP or phenols are in detectable concentrations, a toxicity hazard. <br /> The LGE West Farm site is not near a wood treatment facility or any <br /> manufacturing facility and chlorophenols and phenols should not be in the <br /> groundwater. Mining activities will not introduce any chlorophenols or phenols <br /> into the environment. For these reasons chlorophenols and phenol should be <br /> excluded from the parameter monitoring list. <br /> �Tl MOLEN LG Everist Monitoring Plan <br />