Degree of Toxicity above moderate The capacity-related SSOs pose an above moderate risk or threat to potential receptors because, though diluted by I&I, the SSOs are not treated and would contain bacteria at levels exceeding human health standards and potentially toxic to aquatic organisms. Degree of Toxicity: above moderate The blockage-related SSOs pose an above moderate risk or threat to potential receptors because these SSOs consist of untreated sewage. Susceptibility to Cleanup or Abatement 1 0 Susceptibility to Cleanup: no For capacity-related SSOs, less than 50% of these SSOs was amenable to cleanup or containment because the collection system, storm drains, and creeks were also flowing full at the time. Susceptibility to Cleanup: yes For blockage-related SSOs, greater than 50% of each was susceptible to cleanup as the Discharger response time was adequate (average of about 1 hour). However, we note that the actual average SSO recovery was about 27 percent. Final Potential for Harm Score 5 5 This is the value for capacity-related SSOs. This is the value for blockage-related SSOs
Degree of Toxicity. Above Moderate Milk and propylene glycol pose an above moderate risk to aquatic species. While the apparent toxicity is low, the BOD of milk and propylene glycol is significant and has the propensity to deplete oxygen in receiving waters. The BOD of milk is on the order of 100,000 mg/L, and the BOD of propylene glycol is higher. The discharge effluent limit for BOD is typically around 30 mg/L. The concentration of BOD in very high quality to moderately polluted waters is between 1 and 8 mg/L. Susceptibility to Cleanup or Abatement 0 Susceptibility to Cleanup: yes 50 percent or more of the alleged discharge was susceptible to cleanup or abatement. SSI flushed Facility storm drains and removed up to 5,800 gallons of water, milk and propylene glycol from Xxxxxxx Canyon Creek to the satisfaction of the California Department of Fish and Wildlife representative onsite.
Degree of Toxicity. Moderate A score of 2, moderate, is selected because levels of nitrogen discharged to groundwater pose a moderate risk to human health. Nitrogen discharged from the facility (over 200 mg/L) may elevate nitrate concentrations in groundwater to levels that exceed the U.S. EPA Maximum Contaminant Level (MCL) for drinking water (45 mg/L). Nitrate exceeding the MCL can cause methemoglobinemia.2
Degree of Toxicity. Acute toxicity testing is a direct measurement of the toxicity of the discharge on juvenile fish. In this case, the Discharger continuously subjects rainbow trout, which is an indicator for thousands of other species that reside in San Francisco Bay, to its effluent for 96 hours. Therefore, the Regional Water Board alleges that the degree of toxicity of the discharge from these violations is high.
Degree of Toxicity above moderate For the April 2, 2017, SSO, an “above moderate” degree of toxicity is selected because the sewage discharged was not treated, was potentially toxic to aquatic organisms, and contained bacteria at levels exceeding human health standards. Therefore, the discharge posed an above moderate risk to potential receptors. Susceptibility to Cleanup or Abatement 0 Susceptibility to Cleanup: yes The April 2, 2017, SSO occurred during dry weather; therefore, greater than 50 percent of the SSO was susceptible to cleanup. However, the Settling Respondent did not recover any of this SSO. Final Potential for Harm Score 6 A value of 6 (3+3+0) applies to the April 2, 2017, SSO.
Degree of Toxicity. Significant The discharge consisted of pure cellular concrete. Cellular concrete poses a significant threat to potential receptors and is detrimental to aquatic life. Lime, a constituent of cement, when dissolved in water can raise pH to above 12, which is caustic, corrosive, and fatal to aquatic life. • In general, fish and other xxxx-breathing organisms subjected to high pH suffer the following: (1) extreme respiratory dysfunction from either direct chemical erosion (similar to burning) of sensitive xxxx tissue and/or impairment of gas exchange at the xxxx surface; (2) irreversible chemical xxxxx of optic and olfactory tissues; (3) loss of equilibrium due to respiratory distress and evacuation of the gas bladder, and 4) ultimately death (XxXxx and Xxxx, 1971). • Water Quality Publication 3-A of the California Water Resources Control Board, page 236, discusses how extreme pH levels are lethal to common fish and invertebrate species. Some fish, for example, will die at a pH of only 9.2, but even the most resistant fish species tested cannot survive long at a pH of 10.1 (DFW Biosignificance Report). In addition, the concrete mixture included a protein stabilized surfactant foam that has moderate toxicity to aquatic species that are dependent on the transport of dissolved oxygen (MSDS). • 96hr LC50 = 87 mg/L for fathead minnows PENALTY FACTOR ASSESS- MENT DISCUSSION • 48hr EC50 = 321 mg/L for water fleas Suscepti- bility to Cleanup or 0 Susceptibility to Cleanup: Yes Greater than 50 percent was susceptible to cleanup. The Discharger removed >50 percent of the cellular concrete from the Creek channel and storm drain system. Abatement
Degree of Toxicity. The evaluation of this factor 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. Potential receptors are human, environmental, and ecosystem exposure pathways. In this case, the sanitary sewer overflow was raw sewage, and is known to contain highly elevated concentrations of coliform organisms, biochemical oxygen demand, and ammonia. Discharges of sewage to surface water must typically be treated to a high standard to prevent adverse impacts to aquatic life. Toxicity is the degree to which a substance can damage a living or non-living organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ. In this case, the discharge consisted of raw sewage, which contains pathogens, nitrogen, ammonia, and biological oxygen demand. Fish are highly sensitive to even small concentrations of ammonia. Elevated levels of these constituents can lead to low dissolved oxygen in the receiving water, impacts to aquatic life, and impacts to human health. Because the discharged material possesses “an above-moderate risk or a direct threat to potential receptors,” a score of 3 was assigned for this factor.
Degree of Toxicity moderate The 1.6-MG discharge posed a moderate risk because the discharge fits the Enforcement Policy definition that “… the characteristics of the discharged material have some level of toxicity or pose a moderate level of concern regarding receptor protection ….” The wastewater is chlorinated to as high as 3.4 mg/L. The U.S. EPA Water Quality Criterion for chlorine to prevent acute (lethal) effects to aquatic life is 0.019 mg/L.
Degree of Toxicity moderate The 2.2-MG discharge posed a moderate risk because the bacteria and viruses in undisinfected wastewater fit the Enforcement Policy definition of “… pose a moderate level of concern regarding receptor protection.”
Degree of Toxicity moderate The 5.3-MG discharge posed a moderate risk because the pollutants in primary wastewater fit the Enforcement Policy definition by posing “…a moderate level of concern regarding receptor protection.” Primary treatment typically achieves only about 30 percent BOD and 60 percent TSS removal whereas the minimum standard for secondary treatment is 85 percent removal.
