HAVERHILL - On-again, off-again plans to bring a new coke plant to Haverhill may be on again.

Sun Coke, a Knoxville-based subsidiary of Sunoco, has considered putting a coke plant in Haverhill for several years, but the up-and-down domestic steel industry has always put a damper on its plans.

Now, company officials say they are close to finalizing a long-term contract that would allow construction of an estimated $135 to $175 million facility in one of two locations: Haverhill or Indiana.

"This is definitely on the front burner again," said Dale Walker, senior vice president of operations with Sun Coke. "The steel industry has really been through a tumultuous time. We've had this project close several times, and the customer was in the position where they could not make a long-term commitment."

Coke is produced by heating coal to extreme temperatures in absence of air. The coke is used primarily in blast furnaces in the production of iron and steel. Walker said Sun Coke's process is a unique, state-of-the-art process that "really sets the standard for coke plant emissions in the U.S."

"The way our process works, we don't make any chemical byproducts," he said, adding that the only real byproduct of the process is super-hot, inert gases.

Walker said the ultimate decision about where to locate the plant will be decided upon in the next few months, but that each potential location brings its own benefits.

A major benefit to Sun Coke by locating the facility in Haverhill would be a spin-off effect with its sister company, Sunoco. The adjacent Sunoco chemical plant could use steam generated at the coke plant instead of high-priced natural gas.

"If we're going to do this in Ohio, we have one opportunity to do it," Walker said, referring to the critical timing involved in planning a plant that would work in tandem with the existing Sunoco chemical facility. "The timeframe is pretty short."

Economically, construction of a plant in southeast Ohio could bring hundreds of jobs in the construction phase.

"It's a sizable number, probably 800 at its peak," Walker said, adding that when operational such a facility would probably initially provide 50 to 60 jobs.

Sun Coke requested a modification of its original permit from the Ohio Environmental Protection Agency. Walker said the modification was necessary to allow the facility to be better constructed in phases.

The possibility of the new plant has economic development experts hopeful that if built, the plant may be the first ray of sunshine on the economic horizon.

Bill Dingus, executive director of the Greater Lawrence County Area Chamber of Commerce, said construction of such a plant could have "tremendous residual effects" on Lawrence County.

"The area from between Wheelersburg and Hanging Rock is really a joint community between Scioto and Lawrence counties," Dingus said. "We really view that as an extension of Lawrence County.

In addition, he said having a source of coke in the area could spark other iron-related industries.

"Coke is not a finished product," Dingus said. "It's usually used to develop other products. To have a close resource will definitely be a benefit."

Even though the outcome is not finalized yet, Dingus sees the selection process as positive for the area.

"Just the fact that we're still in the running is excellent," he said. "It's nice to be around the table."

So what are the odds the plant will be built in Haverhill?

"It's too early to tell," Walker said. "We like the idea of it because it's associated with an affiliate company. This is something we've hoped would happen for a long time. We've certainly felt very welcome in the community."

For more information about Sun Coke, visit: www.suncoke.com. Sunoco Inc. (NYSE: SUN) closed at $42.40 Monday, up 19 cents.