The Old Baumgartner Road Bridge in Oakville will be closed until at least October as county officials work to replace the 70-year-old bridge after it was damaged beyond repair during heavy spring rains.

Contractor United Bridge Builders was set to begin preparing for bridge demolition as soon as Tuesday — after the Call went to press — with demolition to follow soon, county Department of Transportation spokesman David Wrone told the Call.

“We expect the bridge to be rebuilt and the road reopened by early to mid-October, barring some horribly nasty weather,” he said. “And if we get two to three weeks of continuous rainfall, that’ll slow it up a bit.”

The county closed the bridge in April after inspectors declared the bridge unsafe to cross when severe storms damaged the concrete abutments that hold up the bridge deck, worsened by heavy currents from Mattese Creek, which crosses under the bridge.

The aging concrete bridge was already on the county’s radar for replacement, and officials sent out a request for proposals, or RFP, in December to replace it as part of a primarily federally funded project with an estimated cost of $821,825.

That estimate included some road re-alignments that the county decided not to pursue, so United Bridge Builders was the lowest bid at $518,000, Wrone said.

“The bridge would have been closed eventually, but it was just moved up a bit by the powerful erosion,” he said.

Until the bridge is replaced and reopened, residents have to circumvent it by taking Heintz and Baumgartner roads. When school starts next month, Mehlville School District buses will also have to bypass the closure by taking the same alternative bus stops the district initially used in the spring.

Construction took months to get off the ground because of utility-related issues that were unavoidable, Wrone said, including a sanitary line of the Metropolitan St. Louis Sewer District that ran through the creek near the bridge that had to be moved.

The county also had to schedule two times for Ameren Missouri to shut down power to its lines near the bridge for work to take place, he added.

Old Baumgartner is one of three decrepit bridges across the county that inspectors have been eyeing for years. In 2013, the county requested that East West Gateway add replacement of the bridges to the region’s Transportation Improvement Program that places a priority on projects for federal transportation funding.

The county has four full-time bridge inspectors who inspect the 200 county-owned bridges at least once a year, and more if a bridge has issues that need to be continually monitored, Wrone said.

“I can’t tell you if (Old Baumgartner) was the second worst or first worst, but it was certainly in bad shape,” he said. “We have four full-time people who do nothing but inspect bridges and make sure our system is safe.”