Officials from two Wisconsin state agencies and the Rock-Koshkonong Lake District say surveying efforts are underway to determine how much and in what year debris recently found underneath the Indianford Bridge was placed in the Rock River.
State agencies involved include: the Department of Transportation (DOT) and the Department of Natural Resources (DNR).
The debris was located after GOE, an Iowa-based dive team, investigated the riverbed on Aug. 24. The team was hired by RKLD after area residents said they saw materials falling from the bridge during construction last year, RKLD officials have said.
According to DOT Indianford Bridge project design engineer Kurt Johnson, a team, including two DOT surveyors and DOT project manager Mark Schweiger, arrived at the bridge last Thursday, Oct. 3, to document debris underneath the bridge, and determine, if possible, how and when it had been placed.
RKLD Chairman Alan Sweeney and a representative from Black River Falls-based Lunda Construction, the company hired by the DOT to perform bridge repair work last year, accompanied the team, Johnson said.
“We know there is debris in the river from our construction project last year,” Johnson said.
According to Johnson, DOT surveyors were hoping to determine how much debris was underneath the bridge and its origins. An older bridge, spanning the Rock River in Indianford, was demolished in 1955. He said a question remains about whether all the debris under the bridge was from a single project, citing the potential for a buildup of debris from more than one project.
Said Johnson: “Another aspect has to do with where the bridge is located. It is relatively close to the dam and very close to a lot of current. The most important thing is safety and that’s what we are dealing with during construction.
“During construction last year, and this year, the water was high and there is a lot of flow there. We have to be sure we are not putting employees at risk.”
A “limited debris” protocol was allowed for the bridge construction project, he said.
As of Oct. 7, Johnson said he had not yet seen any findings from the DOT surveyors’ analysis.
A DNR survey had been recently rescheduled. After both the DNR and DOT surveys are completed, the two agencies will meet, he said.
“We hope to have both surveys completed by the end of October.” Rain and high water could interrupt or postpone the process, he said.
“Last Thursday, there were high flows in the river. The DNR is facing the same constraints. Another aspect is low visibility in the water. It’s hard to really see anything,” Johnson said.
DNR Environmental Analysis Specialist Shelley Warwick said the DNR was planning to send a conservation warden to the site on Oct. 7. The action was postponed due to high water, she said, but was rescheduled for Tuesday, Oct. 15, with hope that water will recede and there will be less turbidity.
Warwick said she and a DOT representative were also planning to attend.
The conservation warden will use an underwater camera, she said. Water cloudiness is expected to be a challenge at the site, she added.
“We will be reconvening toward the end of this month to discuss our next steps, that are yet undefined,” she said.
Typically when safety hazards are identified, there is contractual language used by the DOT limiting debris that can enter the water to “not over 5 inches in diameter,” she said.
Depending on the circumstances, language modifications can occur on a case-by-case basis. The goal is to obtain a balance between environmental concerns and safety, Warwick said.
Describing activities from Oct. 3, Sweeney said the DOT surveyors used sonar equipment, which he described as “similar to a fish finder,” to locate debris.
The team also brought hydro camera equipment, Sweeney said.
“They walked the bridge several times … and they took some pictures,” Sweeney said.
The process took about three hours, he added.
Describing the mechanics of sonar, Sweeney said the device “shows a rectangular bar reflection of what is out there.”
After viewing images made by the sonar device, Sweeney said: “Yes, they did find something, but whether it was a pile of rocks or concrete was hard to tell. I assume on a sandy bottom river it is not a pile of rocks.”
High water and fast-moving currents made using the equipment difficult, Sweeney said, but the team was able to see some concrete with rebar after lowering a hydro camera on the upside of the river and behind a pier near the west bank where there was less turbulence, he said.
“We are undergoing a process and waiting to see how it plays out,” Sweeney said.
In the interim, he said, any information he receives from the DOT or DNR will be shared at the next RKLD board meeting, scheduled for Oct. 17, 6 p.m., at the Edgerton City Hall, he said.