Backfilling a stretch of a sewer ditch is a Cat backhoe while a Cat dozer partially covered by the backhoe spreads fill throughout the sewer cut and a Hamm roller follows to compact soil. Approximately 72,000 ft. (21,960 m) of storm and sanitary sewer and
Just south of the small city of Stillwater, Minn., on the shore line of the St. Croix National Scenic Riverway bordering the state of Wisconsin, the town’s residents, visitors and interstate commuters are seeing a new, diamond interchange take shape above the river’s bank.
Sparked by the construction of the long anticipated replacement to Stillwater’s historic lift bridge, the interchange will connect Minnesota trunk highways 36 and 95 to the future bridge crossing over the river to Wisconsin TH 64.
The Lift Bridge, for decades carrying traffic volumes well beyond its original design capacity between the states of Minnesota and Wisconsin, is located in the heart of Stillwater, approximately 20 mi. (32 km) east of St. Paul and Minneapolis. The next nearest interstate crossing is approximately 9 mi. (14 km) to the south.
This river town is a regional attraction and well known for its bucolic qualities, small shops, pubs, restaurants and recreational activities on the river. The new bridge will by-pass Stillwater and eliminate the current and congested mix of interstate and visitor traffic running through the city’s downtown center and free up the downtown streets for its residents and visitors
Before construction began, TH 36, an east/west trunk highway running east out of Minneapolis rolled into Oak Park Heights, another small river town located about a mi. south of Stillwater. As the highway dipped down the slowly descending hill, it made a sweeping turn to the north on a fly-over bridge and merged with northbound TH 95.
Continuing north, the highway brought motorists into the shopping and business center of downtown Stillwater and to the narrow, two lane lift bridge which crosses over the St. Croix River nearly at water level.
For the interchange construction, the design-build team of Ames/Lunda Joint Venture took on the project with a bid cost of $58.1 million. The total estimate for the bridge construction and approaches on both sides of the river is $580 million to $676 million.
Both companies take on projects throughout the mid-west. Ames Construction is based out of Burnsville, Minn., and going into 51 years of experience and specializes on heavy civil and industrial construction.
Lunda Construction was founded in 1938 and has its headquarters in Black River Falls, Wis. It takes on heavy civil, bridge and industrial construction.
With federal approval and financing in place after decades of discussion, technical and environmental studies and reports, pier construction for the new bridge began in May, 2013. While pier construction continued on the flowing river with very little disruption to the area’s residents, visitors and commuters, it has been a much different story on dry land.
As barges stationed with cranes, backhoes and construction crews clustered around the sites of the pier construction on the wide expanse of the river, dozens of workers moved in on 175 acres of a small hill rising above the river’s west bank.
Though at times the weather was hot, the work hard and the hours long, the construction crews had a clear view of the on-going pier work for the new St. Croix River Crossing and the tree covered bluffs of the scenic St. Croix River Valley.
Supported by a good contingent of heavy equipment, Ames Construction excavating and grading crews wasted no time. They methodically and quickly rearranged the local landscape, topography and old highway connection to fit in the new highway interchange linking the two Minnesota highways and local road network to the future bridge.
Staff from both the Minnesota Department of Transportation (MnDOT) and Ames Construction are pleased with the progress to date on the interchange work.
“I think Ames Construction has done a very good job,” said Jon Chiglo, MnDOT project engineer for the work. “They had a little bit of a late start because the contract was executed a little late. All in all, though, we’re on schedule to complete the work as intended by the end of next year.”
“Work went well in 2013. The schedule was very aggressive yet the contractor and owner were able to mitigate issues to meet the contract milestones,” added Jason Block, project manager of Ames Construction.
Along with building the interchange, the scope of the project includes the reconstruction of 3 mi. (4.8 km) of TH 36 and 1 mi. (1.6 km) of TH 95, laying and relocating thousands of feet of water and sewer mains including several private utilities. Nine filtration ponds will be dug as part of the storm sewer system.
The contract also called for the reconstruction of the Beach Road Bridge which carries local traffic over TH 36 nearly a mi. (1.6 km) west of the river.
For most of the construction season, the site of the road work looked like a giant sandbox filled with every kind of heavy equipment.
Scattered throughout the project last summer at any one time were more than two dozen pieces of heavy equipment including Cat backhoes, dozers, loaders, blades and Bobcat and Volvo equipment. Side and belly dump tractors and trailers roamed in between the digging and grading work moving materials in, out and throughout the site.
At peak construction time last year, Block estimated there were 80 construction workers on site and approximately 80,000 man hours were worked through the end of last year. Though weather has not created any major delays, comfort levels for the working crews have taken a hit with a temperature swing of 100 degrees between the hot, tropical summer of last year and the sub-zero artic cold of this winter.
Even with a June, 2013 start, construction crews met the fast paced construction schedule when they shut down late last year.
Crews took down the fly-over bridge early on in the construction season and completed most of the interchange last fall. Approximately .5 mi. (.8 km) of TH 36 was completed and about one mi. (1.6 km) of TH 95 was paved. And, the new Beach Road Bridge was finished and opened on schedule for the residents of Oak Park Heights and Stillwater.
Last years’ work was notable for the large amount of cut and fill caused by the hill side terrain and its convoluting contours. It affected every part of the job from the surface road work to the underground utilities, Block said.
“There is a significant cut on old TH 36 to build the new road and we took that cut and placed it for the embankment on new TH 95,” he said. At the same time, “we slid the new alignment of TH 95 a couple of hundred feet to the west up into the bluff where it is probably 30 feet (9 m) higher than the old road.”
“There was a tremendous amount of excavation for the sewer work because of the existing contours and grades out here,” Block continued. “We had one manhole where we had to dig down 38 feet to tie in to so we had to engineer shoring or slide rail boxes for that. We had two double back trench boxes in service for most of the project to date.”
Pipe crews will eventually lay approximately 45,000 ft. (13,700 m) of 12 to 60 in. (30 to 152 cm) storm sewer, 16,000 ft. (4,880 m) of sanitary sewer and 19,000 ft. (5,800 m) of water main.
Excavation quantities include 4 million cu. yds. (3.06 million cu m) of excavation for the road and sewer work and 3 million cu. yds. (2.3 million cu m) of excavation for the ponds.
Paving crews are expected to place 78,000 ton (70,200 t) of asphalt and pour 2,000 cu. yd. (1,530 cu m) of concrete for the Beach Road bridge and curb and gutter work.
Sewer work involved several pipe jacking operations including a 72 in. (183 cm) storm sewer pipe. Crews pushed three of them under a set of railroad tracks to the nearby Xcel King Electric Energy plant and the other below TH 95.
Construction crews kept both highways open to traffic except for one weekend closure of TH 95 to take down the 400 ft. (122 m) fly over bridge.
“It went well,” Block said of the closure. “We were able to shut down 95 on a Friday night last spring and we had it back open by mid-day that Sunday.”
Demolition crews recycled the rebar and concrete from the bridge to be used on other projects. However, crushed rock and recycled bituminous stripped out from the original road pavement were used as road base on this project while excavated dirt was trucked throughout the site for fill.
As demolition crews tore into the bridge, sewer crews took advantage of the road closure to dig three storm sewer trenches across the closed highway.
The mid-June start to this project was one of the bigger challenges to this project because of the amount of work scheduled.
“Our project is a design-build, so when we were awarded the contract, we were also required to do the design,” Block said. “After we generated the design drawings and started construction, our schedule was very abbreviated with the relocation of TH 36 and 95 and with all the underground utilities we had to complete.
“To keep on schedule, twelve hour work shifts were common on this project as well as some night work on some parts of the job to minimize the impact on traffic,” Block said.
As in any highway project that creates disruption to daily traffic patterns and habits, advanced and on-going publicity plays a big part in the coordination of construction staging and the success of the project itself.
“There are a lot of dynamic things happening in a very small area and it’s important for folks to know what is coming up,” said Jessica Wiens, MnDOT public information officer.
MnDOT public information staff is relying on all electronic and traditional methods to get the word out including the MnDOT Web site for this project, e-mail updates to approximately 2,600 registered users to date and a Facebook page.
This road project in combination with the bridge construction, though, stands out among the many active MnDOT projects Wiens remarked, because of the high public interest in the construction of the bridge.
“Because the bridge is so many years in the making there is a really high level of interest in not just the traffic impacts but what is the engineering behind the bridge design and what is happening on the river,” Wiens said.
A recent survey by MnDOT staff showed that the public is happy with the public information campaign surrounding the bridge and road work and are hungry to learn more about the details of the bridge construction itself.
“We had a lot of positive feedback regarding the information we’re sending out,” Wiens said. “They want more pictures and explanations to what specifically the crews are doing on the river as opposed to just the daily traffic impacts.”
Much of the information distributed to the public addresses the bridge construction with pictures, videos and graphics to describe in layman terms the principles behind the work going on in the river.
This coming construction season, though, Wiens expects traffic impacts will have a higher following since the last stretch of TH 36 reconstruction will take place surrounded by businesses and residents.
“There are a lot more residents and businesses impacted by the 2014 construction than last year. So, right now we’re executing our strategy to keep everyone informed,” Wiens said.
When crews return to work this spring once the long, cold winter relinquishes its hold on Minnesota, Ames workers will complete the remainder of the TH 36 work on top of the hill, complete the final section of the TH 95 work and lay the remaining pipe.
All road approach work on the Minnesota side of the river will be completed late this fall. The road connection to the new bridge on the Wisconsin side of the river will begin this spring. MnDOT and the Wisconsin Department of Transportation (WisDOT) expect to have the new bridge open for traffic in the fall of 2016.