FORT COLLINS, Colo. — Fallout from the March concrete spill that killed 5,600 fish in the Big Thompson River has heightened considerations of how those rebuilding U.S. Highway 34 will protect the embattled river that runs along the highway.

The three-year, $50 million project to repair damage U.S. 34 sustained during the 2013 flood begins in mid-October, closing 3 miles of the highway east of Drake until Memorial Day. Contractors are tasked with creating a more symbiotic relationship between the river and the rebuilt road while avoiding a fish kill or similar ecological mishap during the upcoming years of intense construction in the narrow canyon, reported The Coloradoan (http://noconow.co/2ckGoVr).

“We’re here to do everything in our power to make sure nothing happens like what happened in March,” said Jenny Bradtmueller, district environmental manager at Kiewit, the contractor selected by the Colorado Department of Transportation for the project.

For each of the project’s five phases, Kiewit must compile a stormwater management plan, a lengthy document explaining how workers will avoid impacting the river. Only the plan for the initial phase of construction — the October-to-May closure, which will mostly consist of rock-blasting in two areas — has been completed.

Some of the safeguards in place include:

Placing berms, or barriers, made of onsite material in the middle of the river and placing bulkheads, or walls, upstream to divert water around the construction site.

If groundwater or river water seeps through the berm, it will be pumped out of the work area, tested and treated if necessary before returned to the river.

Daily inspections of the work site and construction materials.

Future construction that carries a risk of concrete or grout reaching the river will use a berm or barrier process, with the potential addition of plastic sheeting wrapped around the berms.

American Civil Constructors inadvertently killed 5,600 fish on the Big Thompson River in March while pouring concrete for a bridge on Larimer County Road 43 near Drake. The Littleton-based contractor began inspecting berms and covering them with plastic sheeting after a suspected issue with a berm led to concrete and grout seeping into the river. The Coloradoan has requested but not received a copy of ACC’s stormwater management plan for the project, which was supervised by the Central Federal Lands Highway Division and Larimer County.

Kiewit’s plan for the first phase of U.S. 34 work is less comprehensive than plans for future phases because initial construction isn’t expected to come into contact with the river, Bradtmueller said. Construction design is still underway for the rest of the project.

The rebuild of U.S. 34 and the river comes three years after a devastating storm unleashed a year’s worth of rain on the canyon in five days. The Big Thompson River hasn’t been the same since.

As soil and rocks slid down mountainsides, the swelling river swallowed debris, clogging pools vital to fishery survival and reproduction. The torrent of water tore apart riverbanks. The aftermath: The river’s famous rainbow and brown trout population was washed away.

Emergency repairs — crucial at the time to rebuild roads and reconnect the stranded tourist town of Estes Park to Colorado’s Front Range — didn’t exactly beckon fish back to the river.

U.S. 34 was reopened to travelers in three months, but the river running along side it was as straight and narrow as an irrigation ditch, according to Coloradoan reports at the time. Its banks were barren. The new Big Thompson lacked biological diversity and a suitable home for fish and other aquatic life.

Because flood mitigation wasn’t part of emergency repairs, the canyon and its residents were no better protected against a flood than they were before.

DRY SEASON:Fort Collins is officially in a drought

“Whenever you have a disaster, you have immediate responsibilities,” said Larry Rogstad, area wildlife manager with Colorado Parks and Wildlife. “There was always a commitment to coming back and making things as good or better than they were before the flood.”

Now, CDOT and about 10 other agencies say they’re making good on that promise.

They’ll rebuild U.S. 34, replacing temporary asphalt, embankment fill and guardrails. They’ll build wider bridges that can carry more water and roads more resistant to wash-out during floods.

They will rebuild the river so it can carry more water and meander through the canyon, remove silt buildup that nature would’ve taken 50 years to clear and replant the banks.

“After the ’76 flood, it took up to a decade for the fish population to bounce back,” CDOT spokesman Jared Fiel said. “This time, we’re going to work with folks so we can create habitat for the fish and that population can bounce back a lot quicker.”

Agencies including CPW, Larimer County and the Big Thompson River Coalition contributed to the design and planning for different phases of the project, and some of those groups will be on the ground assisting with restoration efforts. The groups have been meeting for more than eight months, and Fiel said the unusually collaborative nature of the project has expedited the process.

Fiel said CDOT leaders are confident Kiewit, which also completed emergency repairs on U.S. 34 in 2013, will do the job right.

“They know that this isn’t just a road that takes you from point A to point B,” Fiel said. “U.S. 34 is where you take people when they come from out of town. This is a place of pride and beauty. People hold this area very dear to their hearts, and the Kiewit folks recognize that.”

Timeline

September 2013: A devastating flood destroys much of U.S. Highway 34 and the Big Thompson River, washing out roads and tearing up riverbanks.

December 2013: Emergency repairs on U.S. 34 are completed less than three months after the flood.

June 2015: CDOT picks Kiewit, the contractor that carried out emergency repairs, to rebuild U.S. 34.

March 2016: A construction mishap on Larimer County Road 43, a project unaffiliated with CDOT, leads to an estimated 5,600 fish being killed on the North Fork of the Big Thompson River and the river’s main stem.

July 2016: CDOT begins short-duration lane closures on part of U.S. 34 as rock-blasting begins.

Mid-October 2016 to Memorial Day 2017: U.S. 34 will be closed to all but canyon residents between mile markers 77 and 80 as major rock-blasting takes place.

2019: Projected completion of U.S. 34 and Big Thompson rebuild

Big Thompson fish kill series

This is Part 2 of a series of stories.

Part 1: An investigation of the construction error that killed 5,600 fish on the Big Thompson last spring

Part 3, out later this month: The Coloradoan presents new findings on the fish kill after receiving responses to public records requests.


Information from: Fort Collins Coloradoan, http://www.coloradoan.com