Missouri Wastewater Plant

Wasting no Waste On Lower Meramec

By Bruce Buckley

When the Metropolitan St. Louis Sewer District was formed in 1954, it was charged with the responsibility of consolidating more than 70 independent wastewater districts.

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More than 50 years later, MSD is continuing those efforts with the construction of the Lower Meramec River Wastewater Treatment Plant southwest of St. Louis.

The new plant will replace two existing open lagoon treatment plants, the Meramec and Baumgartner lagoons. The plant will divert discharged treated water, which currently flows to the Meramec, into the Mississippi. It's a project that requires miles of tunnels through rock and wetlands.

The $230 million first phase is being tackled by three teams under separate contracts.

The wastewater treatment plant team, which is led by construction manager Jacobs Inc./Kwame Building Group Inc. Joint Venture, oversees site preparation, the new plant and the 1.5-mi.-long outfall sewer that discharges to the Mississippi.

Construction manager Shannon & Wilson/Black & Veatch Joint Venture of St. Louis is undertaking the nearly 4-mi.-long Baumgartner tunnel. Under a separate contract, Shannon & Wilson/Black & Veatch are also overseeing the construction of a lift station, which will bring waste from the tunnel to the treatment plant.

Accommodating Growth Spurt

The original vision of the Meramec project was conceived in the 1970s, but nearly 30 years later, designers and contractors are working in a much different world.

The area around the plant site has seen tremendous development in recent years, creating thousands of new neighbors. Concerns about odors affecting nearby residents, including pupils at a grade school, led to a design that would keep sewage underground or otherwise enclosed on the plant site, rather than running it through open channels.

"There's been a lot of development since the lagoons had gone in," said Brian Hoelscher, director of engineering at MSD. "We needed to take into account the neighbors' needs as well as the district's need to treat sewage."

Noise and traffic were also concerns. During preparation of the 203-acre site, crews created a new access entrance to help alleviate strain on local roads.

The site lies within a floodplain, so crews brought in approximately 850,000 cu. yd. of engineered structural fill to elevate the footprint of the new plant. An additional 370,000 cu. yd. of fill was added to another area where future expansions will take place.

The main components of the plant include a three-story process building, a secondary treatment building, two primary clarifiers, two trickling filters and two secondary clarifiers. The main process plant is designed in brick and glass with a steel structure.

Sewage at the plant will flow through the 90-ft.-diameter primary clarifiers to the 150-ft.-diameter secondary clarifiers and the covered 120-ft.-diameter trickling filters. The flow moves through a series of pipes with diameters up to 64 in. via an underground gallery that connects the structures.

The process plant itself is set on pilings that run an average of 90 ft. into rock below.

This job created some tricky situations for workers trying to line up the plant with the gallery, which is not on pilings.

"We had differential settlement between the pile-supported structures and the non-pile-supported structures that required some reworking," said Chris Powell, Jacobs Inc. project manager.

The Jacobs/Kwame team also built the 1.5-mi. outfall sewer, which routes a 78-in.-diameter reinforced concrete pipe to the Mississippi. The sewer route, which reached as deep as 20 ft. and went through wetlands, was open cut, backfilled and restored. Mitigation included nearly 11 acres of wetlands design and planting.

Although the treatment plant sits near the Meramec River, MSD chose to divert discharge to the Mississippi.

"The Meramec is one of the most pristine and well-used rivers in Missouri, and we chose to discharge to the Mississippi instead," said MSD spokesman Lance LeComb.

With some careful planning, the contractor, Goodwin Brothers Construction of Crystal City, Mo., kept hassles to a minimum.

"The contractor was able to jump in and do it during the time of year when the river wouldn't bother him that much," Powell said. "They got it completed on time and under budget."

Construction of the treatment plant and outfall projects began in October 2003 and were completed in June.

Tunneling Ahead

Work on the Baumgartner tunnel project and lift station wasn't quite so smooth.

The project, which began in December 2003 and is expected to be complete in October, consisted of digging a tunnel nearly 21,000 lin. ft. long at depths up to 202 ft. below grade through solid limestone and shale.

A tunnel-boring machine was brought in to cut an approximately 12.5-ft.-wide channel that would hold an 8-ft.-wide reinforced concrete pipe. Nearly 37,000 yds. of cellular grout will be placed between the pipe and the tunnel.

The tunnel also includes three 30-ft.-wide access shafts and five drop shafts of 6 ft. to 10 ft. in diameter, which bring flows into the tunnel.

Within the first 7,000 lin. ft. of work, crews struck a horizontal seam in the rock that sent water from the Meramec straight into the tunnel at rates of up to 150 gallons per minute.

"There was a concern that we'd hit a conduit with pretty endless access to water," the MSD's Hoelscher said. "We were lucky enough to have an excavated quarry nearby so we could look at those rock formations."

Unfortunately for crews, the seam ran horizontally through the path of the tunnel, dropping only 20 ft. in elevation across 7,000 ft.

Tunnel boring was shut down, and a $5 million tunnel grouting program began, which delayed the schedule by 43 days.

The delay has sent subs working long hours to get the project back on schedule.

The lift station project, which began in July 2004, was scheduled to complete in March.

Delays in other aspects of the project have caused setbacks, and crews are pushing to complete the station by the end of the year, in time for a mandated plant opening in January.

"The biggest challenge there has been meeting the schedule," said Tom Abkemeier, project manager with Shannon & Wilson. "They were delayed getting started and now they've got subs working double shifts and on weekends. We just need to get the plant and pumps operational on time."

The lift station construction includes a 120-ft.-diameter circular shaft dug 200 ft. deep.

Approximately 100 ft. upstream, a 26-ft.-diameter screening structure is being built.

The 200-ft.-deep structure will contain two 8-ft.-wide bar screens.
Working around the shaft has caused congestion.

"Those guys are working 20 stories below grade in a 120-ft.-diameter shaft with as many as nine cranes sitting around it, lifting people and materials in and out,"

Abkemeier said. "It's tough enough being on a site with three different GCs working in close proximity to each other."

Although the Lower Meramec project will go a long way toward further consolidating the sewage district, the district has other projects under its $3.7 billion, 20-year capital improvement plan that will take other small plants offline and bring their flows to the Lower Meramec.

The plant is currently designed to handle flow of up to 15 million gallons per day, but it can be expanded to 60 million gallons in the future.

Information Superhighways

Missouri's 1,100-plus mi. of interstates 70, 44, 55, 64, 29 and 35 provide critical MiddlOne area where the federal government continues to have a strong guiding role is in technology. Intelligent Transportation Systems are being looked at as a cost-effective way to address congestion.

Basic 511 systems are starting to roll out across the country. The $1.67 billion T-Rex project in Denver is among the new projects that include ITS, using cameras and sensors to monitor traffic while alerting drivers of congestion via dynamic message signs.

This year, Florida became the 23rd state to activate 511 service on its roads.

But the 50-year vision of ITS is more far-reaching. The Vehicle-Infrastructure Integration initiative under U.S. DOT is working with vehicle manufacturers to create information exchanges between vehicles and traffic managers. Data from cars could be collected to identify congestion, and traffic alerts could be sent directly to drivers in their cars rather than via signs.

Mike Walton, professor of civil engineering at University of Texas in Austin, said automated guideway systems could also be created to help manage traffic.

"Fifty years down the road, I think we'll have much of the system in place," he said.
e-America links to the national system.

On Aug. 2, 1956, Missouri became the first state to award a contract with the new interstate construction funds, inking a deal for work on U.S. Route 66 - now Interstate 44 - in Laclede County.

Also that day, Missouri awarded a contract for work on U.S. 40 - now Interstate 70, the Mark Twain Expressway - in St. Charles County. Cameron & Joyce Inc. of Keokuk, Iowa, began construction on Aug. 13, 1956.

For the 50th anniversary, a ceremony and unveiling of a sign commemorating this first construction project under the federal highway act was held June 28, 2006, in St. Louis.

Also, as part of 50th anniversary plans, a public policy forum was held June 22 at the University of Missouri at Columbia. Three panels discussed the past, present and future of the state's highway system.

Even though the interstate system accounts for less than 4 percent of Missouri's total roadway, it carries 38 percent of the state's total traffic volume.

Transportation Dedication

To handle growing traffic concerns, planners are looking increasingly at dedicated lanes. Urban areas continue to look at HOV and HOT lanes to help address congestion. Last year, Virginia DOT signed a $900 million deal with Fluor to construct four HOT lanes on portions of Interstate 495.

With significant growth in truck traffic in recent decades, many experts are pushing for dedicated truck lanes on Interstates.

"Truck traffic has become such a big part of our economy, we'll have to separate them from automobiles in the near future," said Kumares Sinha, a professor of civil engineering at Purdue University in West Lafayette, Ind.

Bridging the Gap

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