By J. Patrick Pepper
DEARBORN — Before the city gets where it’s going, it has to know where it’s been.
At least that’s the thinking in the recent hiring of two consulting firms to evaluate different aspects of the $330 million federally mandated CSO project that haven’t gone according to plans.
The project – which is aimed at eliminating sewage discharge into the Rouge River by containing the overflow in retention structures when wet-weather events overwhelm the city drainage system – has been a source of uncertainty for city leaders since planning began in the early 1990s.
As many as three design concepts were considered before it eventually was decided to pursue the relatively untested — but theoretically least invasive — method of sinking retention caissons at strategic points along the Rouge.
However, the caisson construction has been anything but smooth, with four of the eight sites tied up in litigation between the contractors and the city.
Site 3, between Rotunda and Michigan Avenue on the west bank of the Rouge, is the worst of the bunch. The caisson is incomplete, cracked, out-of-round and leaning to the side. Contractor Walbridge (known as Walbridge Aldinger at the time) walked off the job without completing it because of problems it blames on poor city engineering reports.
Site 5, near the former Visteon office complex at Ford Road and Greenfield, has been another ongoing problem. The contractor, Barton-Malow, has indicated it is willing to work with the city on the issue, but again has contended that poor engineering reports are to blame for the problem.
The other sites currently in litigation are not damaged – just behind schedule.
Mayor John O’Reilly Jr. on Thursday said the hiring of infrastructure consulting firm Parsons Brinckerhoff Inc. should clear up some of the disputes on the damaged sites and help in litigation. PB will analyze all of the paperwork held by NTH Consultants Ltd., the firm the contracted by the city to oversee the CSO, to try to figure out the events that led to such poor construction of the two multimillion-dollar concrete shafts.
“We just need to get an objective set of eyes on this to see what got us to this point,” O’Reilly said.
“The city of Dearborn has never professed to be an expert on the construction of these things, which is why we contracted all this work out in the first place. The contractors were supposed to know what they were doing, and hopefully we will have a better picture of that now.”
In addition to looking at the paper trail, PB engineers will try to determine if the shafts are still usable in their compromised state. O’Reilly said preliminary indications are that Site 5 probably is remediable, but Site 3 is of less certainty.
Any costs associated with the fixes would be sought in the lawsuits, as well as refunds for accepting the damaged structures, O’Reilly said.
Also hired to help re-evaluate the overall capacity of the CSO was engineering firm CDM Inc. The federal Clean Water Act, which mandated the project, provides that the retention capacity must be able to handle the largest flooding event projected over a 100-year period.
But city officials recently realized that the CSO as currently planned could provide more capacity than required. O’Reilly said he believes the discrepancy arose out of the several designs considered over the course of the project, pointing specifically to the “Super Tunnel” design.
The Super Tunnel was a 17-foot diameter tunnel that was supposed to run from one side of the city to the other and provided far more capacity than would be needed. It was a relatively cost-effective solution and considered a cutting-edge design at the time.
Construction was undertaken, only to be abandoned shortly thereafter when it was discovered that bedrock in Dearborn was about three times deeper than the 50 feet initially thought.
But, O’Reilly said, apparently the inflated capacity associated with the Super Tunnel may have been used as the benchmark, instead of the 100-year level when later designs were drawn up. Either way, he said, it doesn’t mean that any of the eight current shafts were unnecessary; rather, further caisson constructions at other sites might not be necessary.
“My goal is to comply with the law and do it as cost-effectively as possible, and that’s why we brought these consultants in,” O’Reilly said.
By J. Patrick Pepper