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Stockton Propeller, Inc., OCI Case #15242 Date Samples Collected: June 3, 2021 Sample SP-04A exceeds the TTLC for chromium and chromium VI, and the STLC for antimony, cadmium, and chromium. Pursuant to California Code of Regulations, title 22, section 66261.24(a)(2), this sample exhibits the characteristic of toxicity. It should be noted that the results were out of holding time, however, the results still exceed the thresholds for chromium V1 using the EPA 7199 standard. Chromium VI concentrations would be expected to decrease over time as there are many more pathways for the reduction of chromium VI to chromium III than there are for the oxidation of chromium III to chromium VI so the value would be slightly higher if analyzed sooner. However, the concentrations of chromium VI found in the sample was high enough that the change in concentration would not be expected to be significant. The laboratory also analyzed the data as a liquid for both chromium and chromium VI instead of a solid. Because of this the results are in mg/L (converted from ug/L for chromium VI) and not mg/kg. Converting the mg/L to mg/kg to compare with the TTLC is approximately 1:1 with the levels recovered so high the minor difference is a moot point. Sample SP-04A also exceeds the TCLP concentration for cadmium, and chromium, which pursuant to California Code of Regulations, title 22, section 66261.24(a)(1)(B), shows the sample exhibits the RCRA characteristic of toxicity and hence is a RCRA hazardous waste. The pH for this sample is 2.16 which does not exceed the regulatory threshold. As noted above, we have not received the laboratory results for Sample SP-04B for neither cyanide nor the Fish Bioassay, when the results come in and if they are deemed significant, we will make an addended report. Sample SP-05A/B: The samples were collected in the warehouse from an unlabeled, one third full, white poly 55- gallon container with no top of"Alodine" rinse water solution. M. Belmont and Stockton Propeller, Inc. staff confirmed that the unlabeled container was another "Alodine" rinse solution. M. Belmont stated that staff dips metal plane parts in the "Alodine" solution and then into the rinse water to complete the process. M. Belmont stated that they allow the rinse water to evaporate to dispose of it and hook up a heating unit to the barrel to accelerate the evaporation. When we were there the heating unit was attached to this container. The rinse water is a waste because they evaporate it to dispose of it into the atmosphere The samples were tested for total metals, WET, TCLP metals, pH, chromium VI, and Fish Bioassay. Sample SP-05A exceeds the TTLC for chromium and chromium VI, and the STLC for antimony, cadmium, and chromium. Pursuant to California Code of Regulations, title 22, section 66261.24(a)(2), this sample exhibits the characteristic of toxicity. It should be noted that the results were out of holding time, however, the results still exceed the thresholds for chromium VI using the EPA 7199 standard. Chromium VI concentrations would be expected to decrease over time as there are many more pathways for the reduction of chromium V1 to chromium III than there are for the oxidation of chromium III to chromium VI so the value would be slightly higher if analyzed sooner. However, the concentrations of chromium VI found Page: 10