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City of Unalaska - Alaska Wastewater Treatment Plant

(SEATTLE - June 23, 2011) - The U.S. Department of Justice (DOJ) has filed a Clean Water Act complaint on behalf of the U.S. Environmental Protection Agency (EPA) against the City of Unalaska, Alaska, and the State of Alaska for long-standing and repeated Clean Water Act violations.

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Overview of Facility

The City of Unalaska (“City”) is a municipal corporation located in the Aleutian Island chain approximately 800 miles southwest of Anchorage, Alaska. The City owns and operates a municipal sewage treatment facility. EPA issued a NPDES permit to this facility on December 15, 2003 (No. AK004345-1). The permit expired on February 1, 2009. Because the City submitted a timely application for renewal, the permit was administratively extended and remains in effect until the State of Alaska issues the next permit.

The City’s wastewater treatment facility serves both the City of Unalaska and Amaknak Island. It is a primary treatment facility that removes solids from domestic and industrial wastewater with a rotary sheer screen, followed by disinfection using ultraviolet radiation. Screened solids are disposed of at the City’s municipal landfill. The City’s landfill contributes leachate to the collection system and is a source of biochemical oxygen demand (BOD) loading to the facility.

The City’s wastewater treatment facility discharges pollutants into South Unalaska Bay, which opens into the Bering Sea. South Unalaska Bay provides habitat for several threatened and endangered species including the Steller sea lion, northern sea otter, humpback whale, fin whale, sperm whale, Steller’s eider, Kittlitz’s murrelet, and short-tailed albatross. Alaska water quality standards designate South Unalaska Bay for use in aquaculture, seafood processing and industrial water supply, contact and secondary recreation, growth and propagation of fish, shellfish, other aquatic life, and wildlife, and harvesting for consumption of raw mollusks or other raw aquatic life.

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From October 2004 through September 2011, the City has reported over 5,500 violations of effluent limits. The following table identifies the specific number of violations for each parameter:

Hydrocarbons 19

Fecal Coliform - Monthly 540

Fecal Coliform - Daily 77

Flow 292

BOD and TSS (mass)-Daily and Monthly 876

BODand TSS (mg/l)-Daily and Monthly 1,299

BODand TSS (% Removal)-Monthly 2,248

Total Residual Chlorine 222

Failure to Sample 4

Total 5,577

The City’s discharge monitoring reports submitted after September 2011 indicate that the City continues to violate its NPDES Permit for several of these limits.

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Injunctive Relief

The proposed settlement calls for the City to construct and operate an upgraded treatment facility by the end of 2015, and to implement several interim measures that will reduce the severity and frequency of violations before the upgrades are completed.

Influent Pump Station Improvement Project – completed and operational by December 31, 2012.

  • This project includes replacing existing constant speed motor drives with either one or two variable speed motor drives. This replacement will permit the pumps to stabilize influent flows and optimize treatment processes. This project is expected to enhance the effectiveness of the current UV disinfection system and significantly reduce fecal coliform in the effluent by the end of 2012. The estimated values of the upgrades are $86,000 or $118,000, depending on whether one or two pumps are needed. 

Landfill Leachate Tank – completed and operational by September 30, 2013.

  • This project includes constructing a storage tank into which landfill leachate will be pumped and aerated before discharge into the sewer collection system. Landfill leachate is a significant source of BOD loading to the treatment facility. Aeration in the leachate tank will reduce the level BOD in the influent. Flow stabilization associated with the leachate tank will further increase the effectiveness of the UV disinfection system. The estimated capital cost is $2.8 million.

Chlorination/Dechlorination System – completed and operational by December 31, 2014.

  • This system includes chlorine contact tanks, a dechlorination system, and related chemical feed equipment. The chlorine contact tanks will have solids removal equipment that will function until the new treatment facility becomes operational. A temporary pump station will be constructed to convey screened wastewater from the existing treatment building to the new chlorine contact tanks. Additional disinfection through chlorination will further reduce fecal coliform discharges. The estimated capital cost is $2.5 million and annual operating cost is $67,000.

Chemically Enhanced Primary Treatment Facility – completed and operational by December 31, 2015.

  • Chemically enhanced primary treatment (“CEPT”) involves chemical addition to enhance solids removal. Chemically enhanced primary clarifiers typically remove 65 to 90% of influent suspended solids and metals and 40 to 60% of the BOD.
  • The CEPT facility includes new head works with screens, chemical addition and flocculation basins, sedimentation tanks and solids processing and handling facilities. Solids processing facilities include a sludge holding tank, sludge dewatering and drying equipment. Electrical equipment upgrades include a new emergency power generator. The new CEPT facility will allow the City to meet its current permit limits. The estimated capital cost is $12.9 million, with a potential additional $2 million for land acquisition, if needed. The estimated annual operating cost is $462,000 per year.

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Pollutant Reductions

Through implementation of the proposed Consent Decree, the City of Unalaska will eliminate approximately 1,029,000 pounds of pollutants each year:

  • Fecal Matter 955,000 pounds per year
  • Biological Oxygen Demand (“BOD”): 59,000 pounds per year
  • Total Suspended Solids (“TSS”): 15,000 pounds per year

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Other Significant Provisions

Fecal Coliform Requirements

The current limits for fecal coliform are:

  • 10,000 bacteria per 100 milliliters (average monthly)
  • 15,000 bacteria per 100 milliliters (daily maximum).

Based on anticipated results of chlorination, the City has agreed to comply with considerably more stringent limits by December 31, 2014:

  • 200 bacteria per 100 milliliters (average monthly)
  • 400 bacteria per 100 milliliters (average weekly).

Reservation Regarding Future NPDES Permitting

Paragraph 66 sets forth the parties’ express acknowledgement that a future NPDES permit:

  • may require treatment methods or upgrades beyond those required in the Consent Decree;
  • that such treatment methods or upgrades may require the City to dismantle, replace, or upgrade the construction projects implemented under the Consent Decree; and,
  • that the Consent Decree provides no basis, evidence, or defense regarding treatment methods and limitations in future NPDES permits.

The reservation of rights in paragraph 66 is, therefore, necessary to ensure that the current enforcement action is resolved without prejudice to EPA’s position on future NPDES permit requirements.

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Health and Environmental Effects

  • Wastewater discharges frequently contain levels of E. coli, other biological and chemical agents that exceed permitted level, including total suspended solids (TSS) and hydrocarbons.
  • Total suspended solids indicate the measure of suspended solids in wastewater, effluent or water bodies. High levels of TSS in a water body can diminish the amount of light that penetrates the water column and reduce photosynthesis and the production of oxygen. 
  • Biological Oxygen Demand (BOD) is an indirect measure of the biologically degradable material present in organic wastes. A high BOD indicates an abundance of biologically degradable material that will consume oxygen from the water during the degradation process. It may take away oxygen that is needed for aquatic organisms to survive.
  • South Unalaska Bay is listed as an impaired waterbody for BOD, primarily due to discharges from seafood processing operations in the area. However, discharges from the City’s wastewater treatment facility also contribute to reduced concentrations of dissolved oxygen in South Unalaska Bay.
  • According to the U.S. Fish & Wildlife Service (FWS), fecal coliform in the facility’s discharge poses a threat to threatened and endangered species in South Unalaska Bay. In particular, Steller’s eiders overwinter in large numbers in the Bay and have been observed roosting or feeding near the discharges from the wastewater treatment facility. This places Steller’s eiders at high risk of exposure to fecal bacteria and other pollutants.
  • Additionally, the outfall from the City’s waste water treatment plant is located within the critical habitat for the northern sea otter. Bacterial infections have been documented in a recent study of sea otters in Alaska. In 2010, FWS raised concerns about the exposure of sea otters to sewage discharges from the City’s facility, which may increase exposure to various infectious agents, and has concluded that discharges from the City’s facility may adversely affect sea otters.
  • The National Marine Fisheries Service raised similar concerns for endangered sea lions when the City’s permit was reissued in 2002.

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Civil Penalty

  • The City of Unalaska, Alaska will pay a total civil penalty of $340,000.
  • The State of Alaska is a co-Defendant in this case; therefore, the United States will not share the civil penalty with the State of Alaska.

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Comment Period

The proposed settlement, lodged in the U.S. District Court for the District of Alaska, is subject to a 30-day public comment period and final court approval. Information on submitting comments is available at the Department of Justice website.

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For more information, contact:

Clarke Thurmon
Water Enforcement Division
1200 Pennsylvania Ave., NW
(Mail Code 2243A)
Washington, DC 20460
(202) 564-5587
Clarke Thurmon (

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