Manhole Rebuild and Cable Modification
The State of Illinois planned an extensive renovation project for the intersection of Rt59 and Lockport Rd. This project impacted our customer’s communications cables in an existing manhole. Our scope of work included rebuilding the manhole without disrupting communications, shortening the new manhole to accommodate the lower subgrade, and relocating the conduit duct packages to make room for a crossing water main.
This project proved to be challenging because our customer brought us in late to this large State road project. As a result we were now holding up the road contractor who was ready to proceed. The pressure was on from the state and their contractors. Now a complex job became more difficult due to a shortened schedule, and the nature of the surrounding environment.
The first problem was traffic control. The safety of the public and our employees depended on a sound plan.
The project was at the Northwest intersection of Rt59 and Lockport Rd. Neither the State nor the Village would let us permanently close down any lanes on Rt59 or Lockport Rd. We were forced to close lanes daily and re-open them at the end of the day. This meant that we also had to set steel plates over our excavation every night. All of this cost valuable time and made it very difficult to complete the job within an already shortened time table. There was also safety concerns due to the large amount of pedestrian traffic that walked in the area of our job site. Overall, a lot of time and effort was spent on devising a traffic control plan that was set up and removed on a daily basis, while still keeping our employees and pedestrians safe. We worked very closely with our in house safety professionals and traffic engineers within the Illinois Department of Transportation to come up with a comprehensive traffic control plan.
The second challenge was poor soil structure. The excavated side walls surrounding the manhole were mostly sand and gravel. This, along with heavy traffic on Rt59 threatened us with collapse of the surrounding road at all times. As a result we had to take extreme care in excavating around the existing manhole. We devised an excavation plan at our pre job meeting with the help of our Safety Director (who is a CSP), a representative from a local excavation safety company, our project managers and IDOT engineers. Together we came up with a shoring and excavation plan that used a combination of a tracked excavator and hydro-vac. truck to excavate the area around the existing manhole walls. We were able to shore up the sides and stabilize the road using a hybrid shoring strategy that utilized timber shoring and hydraulic shoring jacks.
The added challenge that made this project more difficult was the nature of the infrastructure we were required to work around and modify. All of the lines running through the manhole were either older copper cables encapsulated in lead sheath or fiber optic cable. These two categories of cable are both very fragile and sensitive. It is very difficult to navigate around these cables while demolishing and rebuilding a manhole. There is large amount of telecommunications utilization on these lines, including hospitals, fire and police departments. It was imperative that no lines be damaged during construction. We came up with a strategy to build a false roof to collect any debris that would fall into our excavation while we demolished the concrete walls. This allowed us to safely and quickly demolish the manhole roof and side walls without risking damage to any customer equipment.
Experienced employees, pre planning and our large fleet of equipment allowed us to complete this job with no down time, safety incidents or damage to customer infrastructure while completing the task at hand within the shortened time table.
CASE STUDY GALLERY
