2011-11-03_HYDROLOGY - C1982056 (2)

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1D , aoassay Narrative for Twentymile Coal Company — Site 62 3 Quarter 2011 On August 16, 2011 Aqua -Tox, Inc. initiated and conducted a two species, 7 -day, renewal, chronic bioassay using composite effluent samples from Twentymile Coal Company. Subsequent composite effluent samples were received on August 18 & 20, 2011 to complete the chronic bioassays. Each sample was delivered on -site via Fed -Ex or UPS to the appropriate ATI personnel with chains -of- custody for each sampling event. All three sampling events were chilled and preserved with ice /ice packs when received on -site. The samples arrived at ATI with respective temperatures of 12.8, 12.8, 13.2, 13.6, 12.8, 13.0, and 13.4 °C. Each sampling event was given the unique lot # 081611 -labc upon arrival at ATI. The two species utilized per permit regulations were the vertebrate, Pimephales promelas (fathead minnow), and the invertebrate cladoceran Ceriodaphnia dubia. The EPA methods used to conduct these bioassays were method 1000.0 for P. promelas , and 1002.0 for C. dubia (USEPA 2002). Both methods are cited from Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms (USEPA 2002). Modeling the Water Quality Control Division of the Colorado Department of Health's Guidelines for Conducting Whole Effluent Toxicity Tests (1998), each bioassay was conducted under state and federal protocol. The five concentrations of effluent the two species were exposed to during the 7 -day testing period were 12.5 %, 25 %, 50 %, 75 %, and 100% per permit. Both bioassays were run with equal control replicates using MHFSW. Each dilution was made with composite sample effluent and moderately hard fresh synthetic water (MHFSW) prepared in the lab. Site 62 proved to have major detrimental toxicological effects in the form of survival throughout the Ceriodaphnia dubia chronic bioassay. Using the Linear Interpolation method (ICp), the C. dubia IC25survivai >62.50% and the IC25reproduction = 32.55 %. The C. dubia bioassay was analyzed for significant differences in survival and reproduction using the Fisher's Exact Test and Dunnett's Test; significant differences were displayed for survival and reproduction statistics. The C. dubia concentration with least observed effect difference for survival (LOECsurvivai) =75 %. The C. dubia concentration with least observed effect difference for reproduction (LOECreproduction) = 50 %. Site 62 proved to have minor detrimental toxicological effects in the form of survival or growth throughout the Pimephales promelas chronic bioassay. Using the Linear Interpolation method (ICp), the P. promelas IC25survivai >100 %, and the IC25growth >100 %. Utilizing the Steel's Many -One Rank Test and the Dunnett's Test, the P. promelas bioassay was analyzed for significant differences in survival and growth; minor differences were displayed. The P. promelas concentration with least statistical difference for survival (LOECsurvivai) =100 %. The P. promelas concentration with least statistical difference for growth (LOEC =100 %. The 1C25survival values assigned to the Ceriodaphnia dubiva bioassay are below the state mandated 1C25/1WC >100 %. Therefore, based on the analytical computations of these biostatistics, Site 62 is proven non- compliant with the chro is WET portion of its Colorado State Discharge Permit for the third quarter of 2011 (CDPEH 1998). The IC25survival values assigned to the Pimephales promelas bioassay are equal to the state mandated 1C25/1WC >100 %. Therefore, based on the analytical computations of these biostatistics, Site 62 is proven compliant with the chronic WET portion of its Colorado State Discharge Permit for the third quarter of 2011 (CDPEH 1998).