Diving Services, Kennedy Mill Bridge over Herrington Lake
Kentucky Transportation Cabinet
KY 152, Burgin, KY
Kennedy Mill Bridge provides a critical link to KY 152 traffic crossing over Herrington Lake between Mercer and Garrard Counties, carrying nearly 2,000 vehicles per day. Due to a failure in the bridge deck and deterioration of the truss, the original structure, built in 1924, was demolished and replaced with a two-lane continuous span steel plate girder with 8-foot shoulders and no posted weight restrictions limiting movement of emergency services and commercial trucks. Walsh Construction contracted Marine Solutions to provide diving services for the construction of the new bridge, including anchor installation, bridge demolition, multibeam hydrographic survey, and acoustic imaging. The water depth at the new bridge location is 180 feet, therefore the client had to come up with a creative anchoring system for their 400-ton ringer crane and barges. Marine Solutions first task was to install eight 3-inch diameter by 13-foot-long hollow spin lock anchor rods. The crew cored eight 3-1/2-inch diameter by 13-foot deep holes to set anchors in at depths between 45 and 55 feet. The 170-pound anchor was then placed into the hole and set with a hydraulic impact. A 40-inch diameter anchor lug plate weighing 1,000 pounds was then placed and secured on the anchor rod, set with a hydraulic jack to 8,300 psi, and the hollow anchor rod was then pressure grouted. Once completed, the anchors allowed Walsh to moor their equipment and start construction of the bridge. Due to accelerated construction efforts, the bridge was opened 11 months ahead of schedule, much to the delight of residents, marinas, and local officials.