Degree of Toxicity of the Discharge. 3 The degree of toxicity considers the physical, chemical, biological, and/or thermal characteristics of the discharge, and the risk of damage the discharge could cause to the receptors or beneficial uses. A score between 0 and 4 is assigned. The discharge of untreated wastewater to surface water poses an above moderate risk or a direct threat to potential receptors for at least four reasons:
Degree of Toxicity of the Discharge. The evaluation of the degree of toxicity considers the physical, chemical, biological and/or thermal characteristics of the discharge, waste, fill, or material involved in the violation or violations and the risk of damage the discharge could cause to the receptors or beneficial uses. A score between 0 and 4 is assigned based on a determination of the risk or threat of the discharged material. Evaluation of the discharged material’s toxicity should account for all the characteristics of the material prior to discharge, including, but not limited to, whether it is partially treated, diluted, concentrated and/or a mixture of different constituents. Toxicity analysis should include assessment of both lethal and sublethal effects such as effects on growth and reproduction. The Enforcement Policy assigns a score ranging from 0 to 4 based on a determination of the risk or threat level of the discharged material to potential receptors (i.e., human, environmental, and ecosystem health exposure pathways) being negligible (0) to significant (4). The discharged material consists of approximately 450 gallons of potable water and approximately 135 pounds of CETCO Super Gel X which is a drilling fluid additive providing increased lubrication and cooling, solids transport ability, and stabilization of bore holes. Based on the toxicological information in the Safety Data Sheet, Version #45 revised on September 20, 2021 (Safety Data Sheet) for the drilling additive, prolonged inhalation may be harmful, causes damage to organs through prolonged or repeated exposure and prolonged exposure may cause chronic effects. Acute toxicity of the product is unknown. The ecotoxicity in the Safety Data Sheet states that the product is not classified as environmentally hazardous. However, this does not exclude the possibility that large or frequent spills can have a harmful or damaging effect on the environment. Given these facts, the unauthorized discharge posed a moderate risk or threat to potential receptors and the chemical characteristics of the discharged material have some level of toxicity. These considerations therefore warrant a factor of 2 (moderate).
Degree of Toxicity of the Discharge. Significant (4) A score between 0 (negligible) and 4 (significant) is assigned based on a determination of the risk and threat of the discharged material. A factor of 4 is assigned to this discharge. The Enforcement Policy defines a factor of 4 as the “[d]ischarged material poses a significant risk or threat to potential receptors (i.e., the chemical and/or physical characteristics of the discharged material far exceed risk factors and pose a significant threat to potential receptor uses).” Crude oil and produced water discharges pose a significant risk or threat to potential ecosystem health because crude oil consists of harmful pollutants such as total petroleum hydrocarbons and often contain substances such as benzene, chromium, iron, mercury, nickel, nitrogen, oxygen, sulfur, toluene, and xylene which are toxic to fish and wildlife through ingestion and inhalation. Produced water consists of high concentrations of suspended silica and high salinity with the presence of substances such as dissolved sodium ions, potassium, magnesium, chloride, and sulfate. Produced water may also contain naturally occurring radioactive elements such as radium. Fish and wildlife may experience various toxicological effects that include immune and reproduction system issues as well as disrupted organ function. Furthermore, benzene, toluene, and xylene found in crude oil are carcinogenic compounds that can dissolve or deform cell membranes. Cell membranes contain enzymes and transport proteins to cells. Once damaged active membranes may not have the ability to transport proteins leading to cell death. Benzene in particular has the ability to damage cells, cause cellular mutations and cancer by uncontrolled cell growth leading to wildlife and human deaths.
Degree of Toxicity of the Discharge. 2 The degree of toxicity considers the physical, chemical, biological, and/or thermal characteristics of the discharge. A score between 0 and 4 is assigned based on a determination of the risk and threat of the discharged material. A score of 2 is defined as follows: “Discharged material poses a moderate risk or threat to potential receptors (i.e., the chemical and/or physical characteristics of the discharged material have some level of toxicity or pose a moderate risk or threat to potential receptors).” Discharges of sediment to surface waters can cloud the receiving water, reducing the amount of sunlight reaching aquatic plants, clog fish gills, and smother aquatic habitat and spawning areas. Sediment can also transport other materials such as nutrients, metals, and oils and grease which can cause toxicity to aquatic organisms. Excess sediment in water poses a moderate level of concern to ecosystem health exposure pathways because of the likelihood that the discharged material will harm aquatic life. Therefore, a score of 2 was selected.
Degree of Toxicity of the Discharge. Untreated wastewater would be expected to have a deleterious effect on the environment, including causing potential nuisance in the near shore areas. Raw or diluted wastewater typically has elevated concentrations of biochemical oxygen demand, total suspended solids, oil and grease, ammonia, high levels of viruses and bacteria, trash (only in the case of raw sewage) and toxic pollutants (such as heavy metals, pesticides, personal care products, and pharmaceuticals). These pollutants exert varying levels of impact on water quality, and, as such, will adversely affect beneficial uses of receiving waters to different extents. These conclusions are based on general knowledge of untreated wastewater and not on laboratory analysis of any specific SSO discharge conducted by the Discharger. December 17-19 and 22, 2010, SSOs, and Other Capacity Related Wet Weather SSOs The toxicity of the discharge for SSOs that occurred during wet weather conditions was medium. Since storm related SSOs are diluted with storm runoff and groundwater, they would not pose the same level of toxicity as an equal volume of raw sewage during non-storm conditions. While the Discharger provided calculations showing the levels of solids and biochemical oxygen demand for December 2010 SSOs were theoretically within federally permittable discharge standards because of dilution, Water Board prosecution staff maintains that solids and biochemical oxygen demand are just indicator parameters of an acceptable level of treatment, and that low levels of these indicator parameters alone (without treatment) is not proof that the sewage in the December 2010 SSOs were equivalent to sewage that has in fact gone through treatment processes. Biologically treated sewage reduces other pollutants that are not reflected in those two indicator parameters. Viruses and bacteria that are present in undisinfected wastewater at such levels where dilution alone cannot mitigate potential negative effects pose a serious water quality concern. Bacteria and viruses levels in raw sewage are typically tens of thousands times greater than safe levels. The sewage in the December 2010 SSOs was only diluted by ten to a hundred times. Furthermore, samples of the Corte Madera Creek indicated levels above bacteria water quality standards19. Other toxic pollutants such as ammonia, metals, pharmaceuticals, and personal care products, while diluted, may also been present at toxic concentrations in the discharge.
