More than $206 million in improvements to clean the air and water are planned at the Marathon refinery in Stark County.

The work includes $170 million in new equipment to produce low-sulfur diesel fuel, said Michael R. Armbrester, division manager for the Ohio Refining Division.

In addition, $36 million is earmarked to improve waste water from the plant and to build a 10-mile pipeline to the Tuscarawas River in southern Stark County, Armbrester said Wednesday.

Construction of the $170 million distillate hydrotreater is expected to begin in the spring, he said.

At present, the refinery in Canton and Canton Township produces two grades of diesel fuel. The project will mean that those two grades will be discontinued and a new grade with less sulfur will be refined at the plant, he said.

The Canton refinery produces about 1 million gallons of diesel and 1.2 million gallons of gasoline a day, along with kerosene, propane and asphalt.

The change is needed to comply with tightening federal limits on sulfur in diesel fuel.

The improvement is expected to create five to 10 jobs in Canton, Armbrester said.

Construction will be on the refinery’s north side off Gambrinus Avenue Southwest in Canton.

”Making this kind of investment in the refinery really keeps us viable into the future,” Armbrester said.

Marathon has applied for air permits for the project. Those plans are under review by the Ohio Environmental Protection Agency and the Canton Health Department, which handles air pollution matters in Stark County, said EPA spokesman Mike Settles.

Armbrester said the water improvements are necessary because the Ohio EPA intends to tighten the refinery’s discharge permits in 2008 and 2010.

That will require the installation of four heat exchangers costing $2 million to assure that the water being discharged to Hurford Run is not above 98.6 degrees, he said.

There is no maximum temperature on the plant’s current discharges, which typically total 1.5 million gallons a day.

In addition, Marathon will spend up to $4 million to capture and recycle fluoride to keep it from going into Hurford Run.

About 40 percent of the fluoride comes from well water and 60 percent is from the plant and its processes, he said.

To deal with salts in the discharge water, Marathon wants to build a 10-mile pipeline through Canton, Perry and Bethlehem townships. The line, 16 inches in diameter, would run from the Canton refinery to the southwest to the river and would cost $30 million.

The company is determining the best route but hopes to follow utility rights of way for much of the route, he said.

The company currently discharges into Hurford Run, which flows into Nimishillen and Sandy creeks before going into the Tuscarawas River.

The pipeline discharge would have no effect on the Tuscarawas River, and the change would mean less negative effect on the smaller streams, Armbrester said.

He said the EPA is receptive to the change, though no decision has been made.

Plans call for the fluoride and pipeline projects to be done by 2010, he said.

Marathon is the fifth largest refiner in the United States. Its Canton plant employs 585.