"To protect public health and the environment" is the mission of the Columbia Boulevard Wastewater Treatment Plant. Stewardship of our natural resources and service to the community are the underlying reasons that many plant employees chose a career in wastewater treatment.

 

The plant operates every day, around the clock. The staff is specially trained to manage, monitor and adjust the treatment process. Dozens of pump stations and hundreds of miles of sewer lines are part of the system that brings wastewater to the facility 24 hours a day.

 

The Tryon Creek Wastewater Treatment Plant, a second wastewater treatment plant south of Portland, is also monitored at the Columbia Boulevard facility.

 

Portland first began treating its wastewater in 1952. Before then the city's industrial discharges, agricultural waste and sewage emptied directly into the Willamette River causing it to become dangerously contaminated. Fish died and authorities told people to stay out of the water. When Portland citizens realized it would take new infrastructure to help clean up the problem, they voted for a $12 million bond issue to build a wastewater treatment facility.

 

The Columbia Boulevard Wastewater Treatment Plant is the last stop for Portland's wastewater before it's discharged into the Columbia River. A trip through the treatment plant removes most of the suspended solids and dissolved materials and sends a river water quality effluent to the Columbia River. Some of the solids are recycled and applied to land as a beneficial soil supplement.

 

The Columbia Boulevard Plant has a two-phase treatment process. In the primary phase, large debris is screened out and goes to a solid waste landfill. Grease, oil and floatable solids are skimmed off. Settleable solids are collected and thickened prior to further treatment.

 

In the secondary phase, naturally occurring microorganisms feed on organic pollutants in the wastewater and the resulting residue is separated. After disinfection, the water flows into the Columbia River.

 

The final phase is the processing of biosolids. The treatment of solids removed during the primary and secondary phases produces biosolids. The goal in processing biosolids is to extract water to make a concentrated, stable material and to speed natural decomposition. Microorganisms play a key role in this phase too. Microorganisms living at a constant temperature in an oxygen-free environment aid decomposition of solids. Belt presses squeeze out water. Biosolids are used as a soil supplement on dry pasture land.

 

New and innovative wastewater treatment technology is vital to meet the needs of Portland's growing population. The plant has been continually improved and expanded since it was built in 1952. In 1969, the primary treatment process was expanded and modernized. In 1974, the secondary treatment process was added. In 1979, twin belt presses were added. In 1982, anaerobic digesters were expanded.

 

An anoxic flow process added to the secondary phase in 1993 makes Columbia Boulevard one of the largest treatment plants in the country to convert to this process. The $12 million addition eliminates unwanted microorganisms and minimizes the need for chlorination while increasing secondary treatment flow from a maximum of 120 million gallons per day to 200 million gallons per day.

 

Headworks Building In 1997, Environmental Services opened the new Headworks facility, replacing one of the oldest parts of the Columbia Boulevard plant. The Headworks provides preliminary wastewater treatment. Large screens remove debris, grit, and sand from the wastewater flow. The facility is totally enclosed and chemical scrubbers clean the air before it is discharged. Landscaping around the building features native plants, a pond, and a wetlands.
	Dry Weather Primary Clarifiers In 2000, Environmental Services completed construction of new dry weather primary clarifiers. These huge covered, concrete sedimentation tanks are designed to remove solids, oil, and grease from dry weather sewage flow. To control sewage odors, two chemical scrubbing towers capture and clean air from the tanks. The towers can filter about 33,000 cubic feet of air per minute.
Influent Pump Station In 2000, Environmental Services completed construction of the Columbia Slough Consolidation Conduit, or the Big Pipe, to keep combined sewage from overflowing to the Columbia Slough. To get this mixture of stormwater and sewage from the Big Pipe to the Headworks, Environmental Services built a new influent pump station (IPS) in 1999. The IPS is about 96 feet long, 30 feet wide and 40 feet deep. Above ground, the only visible part of the IPS is a small building the houses electrical and control systems. The facility has three small motor-driven pumps that pump up to 30 million gallons per day (mgd) during dry weather. During heavy rain  storms, three larger pumps are activated to pump an additional 75 mdg, making the total pumping capacity 105 mgd.
	Dechlorination Facility Environmental Services uses sodium hypochlorite, a strong bleach, to disinfect treated wastewater before it is discharged to the Columbia River. To reduce chlorine residual to no more than one part per million, Environmental Services built a dechlorination facility on the banks of the Columbia at Hayden Island. The facility uses liquid sodium bisulfite to dechlorinate treated wastewater.The facility opened in 2000 and has a four-cell mixing chamber and a separate 2,000 square foot chemical storage and metering building.

  

The Columbia Boulevard Wastewater Treatment Plant is committed to eliminating odors that are perceptible beyond the plant's boundaries. Environmental Services will spend $5 million dollars to meet that goal by 2006. The plant currently uses natural biofilters and chemical scrubbers to capture foul odors from wastewater and sludge. People who live within two miles of the plant are invited to become odor monitors to help us control odors.