Presently, Portland is already reducing pollutants at their source and plans to expand the practice under their CSO plan. The city will continue to aggressively implement an industrial pretreatment program that requires companies to remove their toxic and other nonconventional wastes from their wastewater before discharging it to the city's sewers. Portland also sweeps its streets twice a year, removing 17,000 cubic yards of material that would otherwise end up in the treatment plant or be piped into the city's waterways. The city will expand its efforts to clean the sewers to prevent waste from accumulating and thus impeding the flow of water to the treatment facility. The city also plans to improve its system's ability to move waste after it gets into the sewer system.
Many sewer systems rely on gravity to get waste to the treatment plant.
Pumping stations are used when gravity can't do the job. The Portland plan calls for optimizing the capacity of two pumping stations, which are now overwhelmed during storms. The city also plans to build a storage facility near one of the stations to detain storm flow, which can then be pumped to the treatment plant in dry periods. Storage facilities are among the more expensive elements of the plan, accounting for just under one-fourth of the total CSO plan costs. Controlling flow before it gets into the sewer system is another major element of Portland's CSO plan.