District combines process treatment and reuse
In 1997, when Chemi-Con Materials announced that it needed to more than double its process water discharge, Port of Moses Lake, Wash., faced a dilemma: It would have to accommodate the company’s need or face losing one of Moses Lake’s major employers. (The port district, chartered as a municipality to encourage economic development in the Moses Lake area, owns and operates a regional airport as well as the corporate park that is home to Chemi-Con.)
Historically, Larson Wastewater Treatment Plant had handled the company’s wastewater treatment. Managing up to 600,000 gallons of flow per day, the facility already was operating at 70 percent capacity and was not designed to remove total suspended solids (TDS) from process water. Therefore, it could not accommodate the proposed increase in capacity (65,000 gallons per day) without modification and expansion.
However, the changes were not feasible; adding pre-treatment technology would cost well over $10 million, and an expansion would likely trigger a long and costly planning process. As a result, the port teamed up with city and county officials, company executives and other local industry leaders to examine the alternatives for treating process water.
The task force wanted to expand treatment capacity beyond the levels stipulated by Chemi-Con, and, in doing so, it hoped to attract additional industry to the area. Land application — using process water from the industrial park to irrigate nearby cropland — was the port’s best bet.
“TDS are low-grade fertilizer — concentrations of boron, phosphorus, calcium, sodium and sulfate,” says Albert Anderson, industrial development manager for the Port of Moses Lake. “Environmentally, land application makes sense because we’re taking a waste product and turning it into a desirable product. And land application is favored by the Washington Department of Ecology for managing TDS, which streamlined the regulatory review process and helped us meet local industry’s needs quickly.”
In mid-1999, Port of Moses Lake began construction of the land-application system. Led by Albany, Ore.-based Cascade Earth Sciences, the development includes a mile-long gravity sewer that collects the wastewater and channels it via a pump station through 3.6 miles of mainline into a lagoon. The 29-million-gallon lagoon is covered with a four-acre, floating, polypropylene cover to keep it from attracting flocks of birds to the airport area.
A second pump station sends the water through 1.15 miles of irrigation pipeline to a pair of computer-controlled center pivot irrigation systems that water 102 acres of cropland. Minerals that are not taken up by alfalfa are flushed to a zone below the roots of the crop and above the level of local groundwater, Anderson explains.
Completed in June 2000, the lagoon storage and field irrigation system handles 250,000 gallons per day and can be expanded to accommodate 1 million gallons per day. Costing $3.8 million, the project was partially funded with a $1.4 million grant from the U.S. Department of Commerce Economic Development Administration and a $1 million loan from Washington’s Community Economic Revitalization Board.
Already, new users are coming online. Four months ago, the U.S. Forest Service began using the system to handle the washwater from a new forest fire attack base at the Grant County Airport. Chemical manufacturer Moses Lake Industries soon will begin diverting its process water to the facility.
For more information about the land-application system, contact Albert Anderson, industrial development manager for the Port of Moses Lake, at (509) 762-5363 or [email protected].
