Caltrans Pours Concrete Into $45M Ten Mile River Bridge Project in Mendocino

Fri July 11, 2008 - West Edition
Frank Hartzell



California constructors have built some of the most spectacular projects in human history including the Golden Gate Bridge, Shasta Dam and drilled the transcontinental railroad through the Sierra Nevada.

But building bridges in the 21st century has proved a vexing environmental challenge with greater cost overruns than all of the above.

Two Bay Area bridges have broken all records with cost overruns in billions of dollars and many years.

A project to build a bridge over Mad River in Humboldt County has baffled regulatory agencies and contractors for four years now, despite a seismic priority.

While the problem seems to loom larger all the time, Caltrans engineers, along with some fellow construction company officials point to contractor Golden State Bridge as one company that has crafted a proactive approach that works for the modern bridge builder — and stays on budget.

“The proactive approach really makes a huge difference,” said Obadiah Elliot, general manager of Castle Concrete Pumping in Santa Rosa, Calif. Elliot’s company recently finished the pumping for a 800-ft. (243 m) deck pour by Golden State Bridge on the $45 million oceanfront Ten Mile River Bridge.

“Golden State Bridge is by far the most organized and proactive company that I’ve dealt with. They are always setting up meetings ahead of time, getting everybody to the table and we think these problems through. If we can’t we go back to the drawing board until we do,” said Elliot.

The approach that has worked for Golden State in building bridges over fish hatcheries in Central California and on the Ten Mile River Bridge project came up in visits to other jobsites where environmental issues had created slowdowns.

Unlike Elliot, the Caltrans workers and some other contractors didn’t want to speak on the record but suggested a story documenting how new strategies can overcome environmental hurdles would be a great idea.

Elliot agreed there are many old timers who are good at bridge building who get frustrated with what they see as red tape.

“They say a bridge is just a bridge, let’s just get out there and build it. Nowdays, in order to get that bridge built you have to be more sensitive to other issues and take a more proactive approach,” he said.

The Ten Mile River Bridge is in California’s Coastal Zone, meaning all activities are regulated by the California Coastal Commission, a separate layer of environmental regulations not found elsewhere, and one known for its independent streak.

Caltrans officials were stunned when their first Ten Mile River Bridge was shot down after all plans had been finalized by the fellow state agency over public access, scenic values and environmental impacts. New plans had to be quickly drafted, with Caltrans officials reporting they worked late nights on that surprise.

The latest environmental challenge on the actual job was a successful pump in June that Castle Concrete did for Golden State, which poured the concrete. William A. Reames of Golden State Bridge characterized the requirement as not letting a drop of water from the cure sweat into the river below from pour of 1000 ft. (304.8 m) of bridge deck.

“They are thinking we have to have zero tolerance, which means we can’t have a drop of water hit the Ten Mile River.We told them that we could not do that and substantially comply with the contract cure specifications,” said Reames.

The compromise found was to keep it just “wet enough,” It was possible not to run water across the deck constantly, thanks in part to the damp coastal climate.

“We could minimize the water runoff, but the deck must be water cured, “ Reames said.

There are problems with that approach of course.

“There is a chance we could have shrinkage cracks which we can fill in,” said Reames.

Thinking ahead has meant understanding how and why different environmental officials will work on the Ten Mile River Bridge project.

An example was timing the driving of the last sheet pile for the shoring to be timed with the tide. That allowed fish inspectors to rescue any trapped fish in shallow water, rather than deep water, saving both time and fish.

“We know what the biologists have to do and we have it planned that we can be working on something else while that is going on.”

It has been as simple as finding out who the bird expert is and getting that person to the job before cutting the trees and having the project held up over an unidentified nest.

Reames says the problems certainly haven’t all been solved and the regulators are holding out in some areas that may be hard to overcome.

Another difficult restriction found on jobs where migratory fish are present and in “typhoon” climates where a dry summer is followed by winter deluge is narrow time frames for work windows.

The original Ten Mile contract called for one long work window followed by much shorter windows in successive years. “We needed the long window the first year. We did not need any window the second year and a long window in the third could result in us not needing a fourth. “

Golden Sate Bridge is working with Caltrans to try to accomplish this.

“Caltrans has the permits and they do the negotiating. We tell them what we can accomplish.”

Whether the job finishes in 2010 or 2011 may depend on figuring a proactive way to make the windows work around early morning pile driving restrictions, earlier sunsets in the fall that far north, a plethora of environmental issues and unexpected factors such as winter rains or even ocean storms.

Vibrating pile, which don’t make as much noise as a pile-driving hammer, were used to get piles started. The contractor built sound protections for the vibrating pile driver as well as the strike hammer.

“Their definition of driving a pile was different from ours. We did it their way and hopefully something was learned from this.”

Like on every job, problems have arisen that defy any advance planning. The worst was unacceptably loud pile driving sounds on one pier, the sounds mysteriously emerging not where originating but yards away.

In that case, a bubble curtain was used to protect fish from pile driving sounds, although fish numbers in the river are uncertain at best. The curtain, used on the new Bay Bridge and Martinez Bridge projects was refashioned for a much smaller and yet equally sensitive context.

Reames sums up the strategy the company uses;

“We met with the agencies prior to and during construction to ensure that we understood what they wanted and that they could see what we were doing. We have made sure that our crews understand how important our compliance is and how quickly we must respond once we discover a problem. We have also been very up front with doing the required reporting if we have a problem rather than trying to hide it.”

Castle Concrete used Schwing Concrete Boom Pumps on the job. For the big deck pump in June they fashioned a 52 meter and 47 meter boom pump and worked them in tandem, with plastic underneath to prevent spills.

The construction workers hustled like an Indy pit crew to maximize the reach of the gigantic pumps, keeping the concrete flowing constantly while containment boxes were moved and the gigantic pumps were switched back and forth.

“It took us 20 minutes to move the pump. everybody was grabbing the outrigger pads and running down the dock.”

Equipment on the Ten Mile River Bridge job included a CMI Terex Bidwell Division deck finishing machine, a Delmag D-46 and two 150-ton Groves cranes.

The proposed $45 million concrete replacement bridge is 1479-ft. (450 m) long and 45-ft. (13.7 m) wide with two, 12-ft. (3.6 m) lanes and 6-ft. (1.8 m) shoulders. A 5-ft. (1.5 m) wide accessible sidewalk will be constructed on the West Side of the bridge to accommodate users of the Coastal Trail, according to the Caltrans Web site. CEG