Cowlitz Tribe submits plan for handling wastewater from planned casino

The Cowlitz Indian Tribe has submitted a proposal to the U.S. Environmental Protection Agency to handle sewage at its future casino resort outside of La Center by injecting up to 400,000 gallons a day of treated wastewater deep into the ground.

The membrane bioreactor system that will treat the wastewater before it’s injected underground is “state-of-the art green technology” designed to meet federal drinking water standards, tribe Chairman William Iyall said.

“It’s a very advanced plant,” he said Thursday. “We’re confident we’re going to meet all the requirements the EPA has.”

The EPA hasn’t finished reviewing the proposal yet. However, such injection wells aren’t unheard of — the EPA has allowed the Tulalip, Nisqually, Skagit, Squaxin and Grand Ronde Tribes to build wastewater injection systems on Tribal Trust lands similar to the one the Cowlitz Tribe has proposed, according to Parametrix, the tribe’s engineering consultant.

The tribe is proposing the vadose injection well system because it cannot hook up to the city of La Center’s sewer system, as the massive casino would be built outside the city’s urban growth boundary. The tribe submitted its initial documents to the EPA in May requesting approval under the Authorization by Rule, which would allow the tribe to proceed with construction without further permits. The Columbian obtained copies of the documents under the Public Records Act.

The tribe already has begun moving dirt at its 152-acre reservation just west of Interstate 5, with an official groundbreaking set for early 2016. Anticipated to open in mid-2017, the $510 million casino-resort will be built in four phases, the first of which will include a new freeway interchange at Exit 16 and a casino-resort with a 67,000-square-foot gaming area, along with restaurants, a showroom and support areas. At full buildout, the project will feature 152,000 square feet of gaming, 424 hotel rooms, restaurants, showrooms, tribal administration offices, retail, restaurants and a gas station.

The tribe’s $13.4 million wastewater treatment and disposal system would include an on-site wastewater reclamation plant. The reclaimed wastewater would be reused for flushing toilets, laundry, summer irrigation and decorative fountains, reducing the amount of water injected into the wells. All reclaimed water lines and valves would be tagged to warn the public it’s not intended for drinking.

Reclaiming the water “mirrors the tribe’s values for protection of all our resources,” Iyall said, adding that as climate change progresses and aquifers dry up, the need for water reclamation will increase.

“There is clearly a need for the future to reclaim this resource,” he said.

Excess reclaimed water would be stored in tanks, treated to drinking water standards and then pumped into seven vadose injection wells ranging from 60 to 160 feet deep, according to a feasibility study by Parametrix. (“Vadose” means unsaturated ground).

The groundwater in the sand-and-gravel Troutdale, Ore., aquifer, which supplies most of Clark County’s drinking water, lies 280 feet below the surface, 120 to 220 feet below the proposed injection zone. The groundwater movement is extremely slow: It would take about six months for the injected water to enter the groundwater and another four years for it to reach the edge of the casino property, according to Parametrix.

To prevent the injection of contaminants into the aquifer, “the facility will require redundancy and a high degree of reliability,” Derek Schruhl with the EPA’s Ground Water Unit stated in his Sept. 4 letter to the Cowlitz Tribe.

There is no confining layer between the Troutdale aquifer and the ground surface, according to the EPA, which informed the tribe in September that any fluid injected into an underground source of drinking water must meet federal drinking water standards.

“It’s part of our review to ensure the systems are designed and operated in a manner that doesn’t endanger the underground drinking water,” Schruhl said Tuesday.

Iyall has agreed to follow the EPA’s conditions, which include creating an operations plan with water sampling to ensure protection of the drinking water below the casino’s well field. In addition, he agreed to install three groundwater monitoring wells upstream of the injection site, in the well field and on the north edge of the property.

The tribe also investigated the feasibility of disposing of reclaimed water using an on-site drainfield, rapid infiltration basin or surface irrigation. However, tests by Pacific Groundwater Group determined the upper surface soils drained poorly and could not handle large volumes of wastewater.