Cowlitz Waste Water Facts
What is an Underground Injection Control (UIC) Program, Class V well?
As outlined in EPA's literature (Basic Information about Class V Injection Wells); "A Class V well is used to inject non-hazardous fluids underground. Most Class V wells are 'low-tech' and depend on gravity to drain fluids directly below the land surface. Dry wells, cesspools, and septic system leach fields are examples of simple Class V wells. Because their construction often provides little or no pretreatment and these fluids are injected directly into or above an underground source of drinking water, proper management is important.
More sophisticated Class V wells may rely on gravity or use pressure systems for fluid injection. Some sophisticated systems include advanced wastewater disposal systems used by industry."
What is Proposed by the Cowlitz Tribe to Manage Wastewater at the Casino Resort?
The Cowlitz Tribe is passionate about protection of the environment and, therefore, chooses to use advanced wastewater treatment prior to injecting the water into the ground instead of "low-tech" methods. Unlike "low-tech" systems allowed under the UIC Program, the advanced treatment system employed by the Tribe uses microfiltration membrane technology that has been used successfully on Class V wells on Tribal Trust Land in Washington State and EPA Region 10 for advanced protection of groundwater. The membrane technology allows the treatment system to produce reclaimed water (reclaimed water in the jar on the right; wastewater in the jar on the left) that has been tested for meeting primary drinking water standards at the end of the treatment process. After advanced treatment, the Class V well will infiltrate the treated water through 120 feet of fine unsaturated soil (vadose zone) where additional treatment and filtration will occur before it enters the groundwater.
How Does the Cowlitz System Compare to a Residential On-site Wastewater System?
Because the Cowlitz Tribe has opted to employ an advanced treatment system rather than a low-tech system, the Cowlitz system has far less impact on the environment than what is typically from single-family residences. By comparison, the initial Casino development (70,000 to 100,000 gallons per day) using the advanced treatment plant will:
- Reduce the biological waste concentrations (biochemical oxygen demand) to 1% to 2% of the concentrations coming from a septic tank. The initial Casino development is similar to having one single-family home (on a septic tank and drainfield) per 75 acres of land or two homes on the entire Cowlitz Reservation (152 acres).
- Reduce the total nitrogen concentration to 6% to 12% of the concentrations coming from a septic tank. The initial Casino development is similar to having one single family home (on a septic tank and drainfield) per 10 acres of land or 15 homes on the entire Cowlitz Reservation.
Unlike a low-tech, on-site wastewater system, the Cowlitz system employs (24 hours/7 days per week) continuous monitoring of the water reclamation plant performance (through a sophisticated controls and reporting system), and overall performance of the system will be operated and monitored by licensed operations staff with overview by EPA through the UIC program.
- Submitted by Michael Ollivant, Project Design and Consulting Engineer, Parametrix Inc.