Prompted by new information on why the first phase of the 7-year-old Chemin Metairie Parkway continues to sink, the City Council voted late Monday to authorize legal action.

The five-member council voted 4-0 — with Councilman Ken Stansbury abstaining — to authorize attorney William Melancon to initiate legal proceedings.

However, the motion to pursue legal action did not specify a defendant, and first-term Mayor Ken Ritter declined Tuesday to name the target. He said the suit would be filed in a few weeks.

The Lafayette-based engineering firm Fenstermaker oversaw design and construction of Chemin Metairie Phase One, a 2.6-mile two-lane road that runs from the traffic circle at La. 92 to a circle at La. 89.

Completed in 2008, the road immediately started to subside and forced the city to close the roadway for repairs. Those repairs turned out to be not enough, and this year Youngsville officials authorized $1.3 million to fix the road again.

William Fenstermaker, the engineering firm’s president and CEO, said in an email Tuesday that the company stands behind its work on the roadway and said Chemin Metairie Parkway has created an economic boon for Youngsville.

“It is unfortunate that the city of Youngsville has chosen to file this suit,” he said. “Hopefully it doesn’t cost the citizens of the city too much because the roadway was built to the standards that they could afford at the time.”

Fenstermaker said he hopes that local residents will “see the value that has been created” and will give the engineers the credit they deserve “once the facts are aired.”

Youngsville council members Monday evening sat from 6 p.m. to past 8:30 p.m. in a closed-door executive session listening to a presentation by Melancon, who has been the city’s attorney over the parkway’s legal aspects since problems arose.

Ritter said council members were presented with new information in the executive session that swayed the council to authorize legal proceedings.

The current work on the road, which entailed digging down into and tearing up the asphalt, uncovered “sufficient evidence” that the road was “not built according to specifications,” Ritter said in a telephone interview.

He declined to get more specific.

Ritter said the road will be back together and ready for traffic by the July 4 weekend.

Dianne McClelland, the only veteran legislator on the council, said, “There was new information about details that absolutely justified litigation for compensation. We’re spending a lot of money on this road.”

Chemin Metairie Phase One’s shortfalls have outlasted the political terms of those who have tried to deal with the problems: former Mayor Wilson Viator is now retired, and four of five council members are gone.

It’s also been a headache for Fenstermaker. In one contentious council meeting in August 2014, Fenstermaker engineer Dax Douet was on the defensive.

He said Chemin Metairie was built for a 10-year life instead of 20 because Youngsville in the mid-2000s had only $7 million to spend. With that budget, the initial road was laid with only 4 inches of asphalt instead of 9 inches, which was called for in the 20-year design.

Douet noted the increased business and gold-plated property values the road brought. He also said heavy-haul truck traffic was in part to blame for tearing up the road. Traffic forecasts back then underestimated the number of trucks carrying cane, cement, oilfield supplies, house-building supplies and other materials that would use the road.

When it came time to build Chemin Metairie Phase Two, Youngsville had $13 million to spend and a blueprint of what not to do. Completed in 2013 with 10 inches of concrete instead of asphalt, Phase Two has not shown signs of deterioration.