Big Ten football equals crowds and traffic in the heart of Madison, WI. About 80,000 people poured into Camp Randall for the opening football game for the University of Wisconsin Badgers on Sept. 5.
Many of those fans traveled down University Avenue, where just a few weeks earlier construction crews were laying multiple utilities in a single trench.
Throughout the street reconstruction project, a strict deadline loomed because the city of Madison and University of Wisconsin were adamant that University Avenue open in time for football season.
That deadline was met – but it was not without challenges.
In October 2008, utilities were given an eight-month notice that the city of Madison was reconstructing University Avenue, a major thoroughfare from the downtown through the campus.
The local combination utility, Madison Gas and Electric Co. (MGE), quickly evaluated its needs. MGE notified the city that it wanted to reinforce its downtown natural gas system and add major underground electric distribution lines to meet future customer demand. Both of these installations are significant energy feeds for Madison and the metro area.
MGE generates and distributes electricity to 137,000 customers in Dane County, WI, and purchases and distributes natural gas to 141,000 customers in seven south central and western Wisconsin counties. MGE is the principal subsidiary of MGE Energy.
American Transmission Co. (ATC) said it was essential that an underground electric transmission pipe be added for future load growth. ATC owns, operates, builds and maintains the high voltage electric transmission system serving portions of Wisconsin, Michigan, Minnesota
By December 2008, the city reviewed the utility infrastructure needs and the looming deadline. Its engineers – working with MGE and ATC – came up with a solution. The only way the work could progress on schedule was if gas, electric distribution and electric transmission shared one trench and worked simultaneously.
This may have been the first time in Wisconsin that these major types of utilities shared one trench.
Due to utility construction work, traffic flow was reduced to one or two lanes on University Avenue. Heavy downtown vehicle traffic backed up and crawled past workers. Students on foot, bikes and mopeds zipped through the area. Getting construction equipment in and out of the area was difficult.
Another aspect of the project was a directional bore required under the adjacent State Street – a popular campus retail/entertainment district. The 900 foot bore was 22 feet below the street with 300 feet of lay down area. This side project was challenging due to the constricted spaces and the many students that frequented the area.
Going into the project, all the parties involved knew that the combination of tight deadlines and spaces would require excellent coordination.
MGE took the lead on the utility work. ATC contracted with MGE to head the construction of transmission facilities.
MGE then turned to its primary contractor – KS Energy Services – to do all the construction work. KS Energy is a provider of natural gas, electric and telecommunications construction services in the U.S. Joining the project as a subcontractor was InterCon Construction Inc., which installed the ATC facilities because it specializes in high voltage underground utility installations.
“The success of this complicated project began with solid relationships,” said Dennis Klumb, president and CEO of KS Energy Services.
John Yogerst, MGE’s Assistant Vice President of Gas Operations, agreed: “MGE and the city of Madison have a long history of working well together. Additionally, KS Energy and InterCon have a good working relationship with each other and with MGE. We knew we could pull together to do quality work and meet the deadline.”
It took six months of meetings to prepare for eight weeks of work. For complicated projects, planning ahead is essential to smooth coordination once workers hit the trenches.
Success is in the details
- Before the bidding process, partners worked closely with the City of Madison so its street contractors were well prepared. Digital files were shared with the city. MGE and ATC had routes marked and inserted into the City of Madison’s CAD file as individual layers and incorporated into the city’s plan set for bidders.
- A narrative describing each utility’s facility and route was included in the city’s specifications. Each prospective bidder was aware of the scope of the utility construction and could bid and plan accordingly.
- MGE and ATC worked with a third party consultant to develop a new design, including a fluidized thermal backfill, so the distribution and transmission could be separated by a three foot allowance rather than the standard six foot allowance.
- Meetings with ATC determined trench cross sections for various trenching scenarios.
- Coordination was key. Weekly meetings were held between MGE, KS Energy and InterCon to prepare for upcoming construction. Partners also held weekly scheduling meetings with the City of Madison and its contractors.
- Individual coordination sessions helped resolve specific issues that kept the flow of pedestrians, vehicles, trains, construction equipment and business deliveries moving.
- The city of Madison was just one of the entities. The partners also worked with Wisconsin’s departments of Administration and Transportation, the University of Wisconsin Facilities Management, Wisconsin & Southern Railroad and local business owners associations.
The joint trench was built in three different configurations:
- First configuration: MGE’s 12 inch steel gas main and the ATC 8 inch steel pipe were installed. The excavated trench cross section was 4 feet wide and 5 feet deep. This gave both steel pipes 2 feet of separation with a standard trench depth of 5 feet. During backfill, the lines were separated with plywood form work so MGE’s gas main could be encased in compacted sand and ATC’s cable pipe could be encased in a fluidized thermal backfill (FTB);
- Second configuration: The concrete encased electrical duct package was added. The excavated trench cross section with all three utilities was 9 feet wide and 6 feet deep. The MGE electric duct was aligned in the middle of the joint trench and maintained 2 feet of separation with MGE gas and 3 feet of separation with ATC cable pipe. During backfill, the gas main was separated from the electric utilities and encased in sand. The electric duct and the cable pipe were encased in FTB to dissipate the heat generated by these utility packages; and
- Third configuration: Electric duct and the cable pipe were installed. This excavated cross section was 6 feet wide and 6 feet deep. Once again, the two electric utilities had 3 feet of separation and were encased in FTB.
In many locations along the route, the three entities used every inch of trench width available.
The work zone was restricted to an area that was 24 feet wide. To maximize efficiency and safety, KS Energy Services staged its work and that of its subcontractor, InterCon Construction. Vehicles in the work zones were controlled using flag persons – directing out trucks with spoil and directing in trucks with sand, concrete and FTB. The steel pipelines were built alongside of the trenches, giving space for welders and pipe layers to work on their respective facilities.
Pedestrian crossings were of utmost importance. Temporary bridges were constructed over the trenches so that pedestrian and bicycle traffic would be unimpeded. In many cases, work was performed below these bridges as pedestrians crossed above. KS Energy often had some of its employees work as “ushers” to help pedestrians cross the busy work zone in areas where large machines and trucks were operating right next to the crosswalks. KS Energy met the goal of maintaining public safety in these areas.
MGE took out of service and pressure tested approximately 6,000 feet of 12 inch steel gas main starting near a 150 megawatt co-generation power plant co owned by MGE and the University of Wisconsin. The main runs along a rail corridor finishing near the university’s football stadium called Camp Randall.
This main had been operating at 175 PSI since installed in 1970. The existing line was tested to 600 PSI and then pressurized to 400 PSI to use it as a feed for the new 12 inch steel main installed along the University Avenue corridor. KS Energy then tied into the existing 12 inch steel gas main and installed operator monitor regulator stations to reduce the pressure from 400 PSI to 175 PSI. This maintains MGE’s feed to its 175 PSI system. KS Energy then installed the new 12 inch .375 wall steel gas main starting from the newly uprated 12 inch 400 PSI gas main.
Electric distribution, transmission
MGE Electric Distribution designed and constructed 2,600 feet of 15 duct, 5 inch concrete encased PVC duct and eight precast manholes. The electric system installation was designed to avoid municipal utility conflicts. Specific orientation and spacing of the electric distribution package and the transmission carrier pipe was necessary to ensure that thermal loading (heat dissipation) concerns were addressed. MGE used FTB to address this concern and to ensure timely backfilling and quality compaction.
ATC installed approximately 6,000 feet of 8 inch steel pipe and three manholes as provisions for future installation of a 138 kilovolt transmission cable. ATC identified the project as a future need, and by installing the pipe early, while the street was under construction, saved approximately 50 percent on the cost of the project. A high pressure, fluid filled design was used to avoid conflicts with existing underground transmission infrastructure in the area.
“The University Avenue reconstruction was one of the most difficult projects in the history of KS Energy Services,” Klumb said. “We successfully met the deadline due to the detailed planning and coordination that made this a team effort. From the top down, there was cooperation from the engineers, surveyors, supply chain, construction companies, utilities and other partners.”
FOR MORE INFORMATION:
KS Energy Services, (262) 574-5100, www.ksenergyservices.com
InterCon Construction, (608) 227-7473, www.infrastrux.com