North Stonington — Following litigation over disputed work on Hewitt Dam, an arbitrator has ordered the town to pay Mattern Construction the remainder of the contracted cost.

The total amount awarded to Mattern Construction was $54,000. However, the contractor has to pay the town $18,300 in additional engineering expenses.

The dispute arose between the town and Mattern as the work on the dam, located on the Shunock River on the Hewitt Farm property, neared completion in June 2015.

At the time, George Mattern, owner of Mattern Construction said, the conflict was concentrated on one item in the budget: the cofferdam, a structure which keeps part of a waterway dry for construction work.

First Selectman Shawn Murphy said in a phone interview last week that Mattern did not construct the entire cofferdam as it was specified in the plan, and since the cofferdam failed "on two or three occasions," the town decided to withhold payment on that item in the contract.

The Board of Selectmen met in executive session several times on the subject last spring.

The town initially paid half of the $100,000 budgeted for the cofferdam, and then only an additional $5,000 after it was completed.

The budget line for the cofferdam was a lump sum, Mattern said, meaning that amount would ultimately be due regardless of how the cofferdam was constructed.

He noted the company had taken responsibility for cleaning up the area when the water spilled over the cofferdam. The arbitrator agreed with his assessment.

"We've probably done 50 projects, 100 projects that contained lump sum and unit price pay items and we've never been questioned on lump sum pay items," Mattern said. "I'm very surprised it happened."

At a Board of Selectmen meeting on Jan. 12, Murphy said he wasn't pleased but that the town accepted the agreement.

"It's not good for the town in the long run, and I don't necessarily agree with the results," Murphy said.

The dispute led to "communication breaking down" between the town and Mattern, according to Murphy, and as a result the town never submitted its punch list of nonconforming elements of the dam that must be addressed for final payment of the contract.

These items include the grout work, which is failing in several areas, and parts of the mortar work where vegetation has grown through.

Murphy said the town would be submitting the punch list now that the arbitration has been completed. Mattern said he "didn't know about the list's existence" until recently.

The dam was damaged in a March 2010 flood that led to extensive repairs, including merging two spillways, reinforcing the walls and the construction of a riprap to prevent erosion.

"I just feel bad for the town of North Stonington in general," Mattern said. "They're getting a reputation of not treating contractors fairly (and) wasting money on legal fees."

n.lynch@theday.com

Twitter: @_nathanlynch