The city of Medical Lake has awarded a nearly $5.7 million contract to a joint-venture partnership headed by Hoffman Contractors Inc., of Spokane, for construction of a new wastewater treatment facility that will serve the Medical Lake area.


The partnership, which also includes Kearsley Construction Inc., of Spokane, is expected to begin work on the treatment facility this month and to complete the project by December 1999, says Doug Ross, Medical Lakes public works director. Hoffman is the managing partner.


The treatment plant is to be built on an about six-acre site in north Medical Lake, near the citys current lagoon-system treatment facility, says Ross.


The new plant will include a 24,000-square-foot aeration basin; two, 70-foot diameter clarifiers; a 4,000-square-foot dewatering building; a 4,500-square-foot final treatment building; a 1,700-square-foot headworks building; a 1,600-square-foot laboratory and operations building; and two small pump-station buildings.


In addition to constructing those structures, the joint venture also will install all of the equipment needed to run the new plant.


Medical Lake currently has a three-lagoon system that discharges treated water into nearby Deep Creek. Ross says two of those lagoons will be abandoned when the project is completed, and the eight acres that they occupy will be drained and used for future expansion of the plant. The third lagoon will remain in use as an overflow area during peak periods.


In addition to the citys lagoon-system, there are two other wastewater-treatment plants in Medical Lakeon the Eastern State Hospital campus and at Lakeland Villagethat handle effluent from Eastern State Hospital and other state institutions nearby and are operated by Washington state. They currently discharge treated wastewater into West Medical Lake, says Allison Esvelt, a project manager at Esvelt Environmental Engineering, the Spokane firm that designed the facility for the city of Medical Lake.


After the citys new treatment plant is constructed, the state plans to remove both of its plants from service. It will erect a lift station at the Eastern State Hospital campus that will pump sewage to the citys new treatment plant, says Esvelt.


The state, which will pay the city for treatment, will install a line to carry effluent from the lift station to the citys treatment plant. The state also will install a second, companion pipe that will carry treated and filtered wastewater from the treatment plant to West Medical Lake. Some treated wastewater from the plant also will be discharged into a tributary that flows into Deep Creek.


The new plant will use an oxidation treatment system and will have the capacity to process about 1 million gallons of effluent a day, Esvelt says. In the oxidation process, raw sewage enters the plant through the headworks building, where it is screened for large objects.


From there, the organic solids enter the plants large aeration basin. Aeration is the process of supplying oxygen to microorganisms, which eat the solids.


After being aerated, the effluent then will enter one or both of the plants clarifiers, which will separate the microorganisms from the wastewater. The wastewater then will move to the final treatment building, where it will be disinfected and discharged either into West Medical Lake or Deep Creek. Meanwhile, the collected solids will be pumped to a sludge storage tank. Two to three days a week, solids from that storage tank will be pumped to a belt filter press, which will squeeze the water out of the waste, leaving a substance thats suitable for composting.


Ross says the new facility is needed because the three older plants cant meet water quality-standards set by the state Department of Ecology. He says the new plant and the states cost in hooking up to it are expected to cost between $11 million and $13 million in all to complete, including the cost of engineering studies, equipment, and construction. In addition to the $5.7 million construction contract and the $2 million to purchase the equipment, the states part of the project will cost $1.8 million, engineering and design of the plant will cost $1.7 million, and at least another $500,000 will be spent on landscaping and a walkway around the plant.


The project is being funded with a grant from the Centennial Clean Water Fund, and with loans from the states Public Works Trust Fund and from the Department of Ecology. The city of Medical Lake is pitching in about $1 million.


The states part of the work will be covered under a separate contract thats expected to go to bid by the end of this year. Ross says the Washington state Department of Social and Health Services, the state agency that operates Eastern State Hospital, will request $1.8 million from the Legislature to pay for that work.