See inside one of the city’s largest sewer pipes as MSD makes progress on repairs
LOUISVILLE, KY – More than 20-feet below Main Street, repairs are well underway on one of the city’s most essential sewer lines. This pipe known as the Ohio River Interceptor carries 40 percent of the community’s wastewater to MSD’s Morris Forman Water Quality Treatment Center for proper treatment and release to the Ohio River.
MSD contractors are currently installing extra support for the failing concrete structure. Ring beams brace the upper and side curves of the pipe while steel lagging is installed between the ring beams to complete the support system. This extra support of the pipe is needed beginning at Fourth Street and proceeding west for 160 feet, due to a structural failure MSD discovered on August 19.
To date, crews have completed 110 feet of this ring-beam and lagging system. Once the extra structural support is complete, crews can begin building a new pipe inside the damaged one. They will do this by installing corrosion-resistant PVC panels that fit together by hand and are sealed to the unique shape of the pipe. MSD is creating the new pipe between Fourth and Seventh streets, and the underground repairs should be complete by the end of the year.
MSD Executive Director Tony Parrott states, “MSD and its contractors continue to work as diligently and safely as possible to repair this essential piece of infrastructure that provides service to 40 percent of Jefferson County. We will continue to communicate our message about the need to repair and even replace infrastructure that is vital for not only the health and safety of our community but for economic vitality as well.”
This link contains video of the installation of the ring beam and lagging system.
Click and drag your mouse over the video to rotate the view (Best viewed in Google Chrome)
Inspection reveals structural failure compounded by heavy rains
On August 19, a routine in-pipe camera inspection revealed that the potential cave-in had become a reality. Contractors discovered a 5- by 2-feet section of the Main Street pipe had collapsed just west of Fourth Street. Further inspections revealed a large void, or empty space, under the pavement just west of Fourth Street. The void was 40-50 feet across in both directions, and 25 feet deep at the worst spot. The void left the roadway unsupported in the area with a gas and water line suspended in the void.
Heavy rains in August compounded the problem by washing the loose sandy soil through into the pipe the hole in the side of the pipe. The force of the water carried this soil downstream in the pipe. The area received more than 4 inches of rain from August 1 through 26, when filling of the void began. Crews worked 24/7 to slowly fill the void with a light-weight grout, making sure the suspended gas and water lines were protected. Surveys show the pavement rose 1.5 to 1.75 inches after the void was filled, as compared to surveys before the void was filled.
Traffic was reduced to only one lane on the north side of Main Street midway between Third and Fourth streets to ensure public safety. An early inspection of the pipe from June 21 shows a deteriorated pipe with exposed rebar, but no cave-in.
MSD commissioned an inspection of the concrete Ohio River Interceptor — an 84-inch sewer pipe — in November 2017 and used technology that allows engineers to analyze the pipe without having to empty it. The resulting March 2018 report, reveals that some of the concrete and rebar support systems have worn away between Fourth and Seventh streets.
MSD closed the southside parking lane on Main Street between Fourth and Seventh streets in April to ensure public safety from the threat of a potential cave-in of the pipe. Work then began with a team of consultants to develop a plan to repair this vital infrastructure with the least disruption to this vibrant area of our community.
The $20 million repair project requires a “pump-around” to remove wastewater flow from the damaged section of pipe so that workers can go underground and make repairs from within the 7-foot tall pipe. Workers enter the pipe through existing hatches in the pavement at Fourth and Main streets.
Constructing the pump-around required seven weeks of basically building a temporary sewer system on the surface with four parallel pipes, which total three linear miles. Wastewater pumped out of the damaged pipe is temporarily re-routed west along River Road to Ninth Street where it re-enters the large sewer pipe and continues its path to MSD’s Morris Forman Water Quality Treatment Center for treatment and release to the Ohio River.
The repair to the pipe and dismantling of the pump-around system should be complete by the end of the year.