Crew installs tidegates

Workers pour concrete into a cast that supports the new Winter Slough tide gate in the Julia Butler Hansen Refuge for the White-tail Deer. The US Army Corps of Engineers is replacing three gates in the refuge. Photo by Stevan Morgain.

Steamboat Slough Road is still closed and work continues on the Julia Butler Hansen refuge tide-gates this week.

The US Army Corps of Engineers have two more weeks of work left on the second of the three tide gates being replaced in the refuge. Last Friday the Corps poured the first of several layers of concrete on the Winter Slough tide gate.

The tide gate replacement is part of the ongoing work in the refuge. The refuge’s old tide gates are being removed and replaced with new self-regulating, side mounted gates that will be less susceptible to clogging at the mouth of the gate.

The concrete work on the Winter Slough gate is the first step in building the concrete collar that will hold the new gate in place.

Corps Supervisor Morris Frazier said each of the concrete pours must pass a test before additional concrete can be added to the mix, and the concrete must have adequate water content to dry properly.

“Concrete gets its strength from how it hardens,” said Frazier. “If it hardens too fast or slow it won’t have the proper strength.”

Southwest Concrete is supplying the concrete.

“The concrete we are using here in the refuge is the same formula used by the Fish and Wild Life Department to build fish-ladders and bulkheads,” said Frazier.

The construction crew started its work by digging down about 20 feet and removing the old Winter Slough tide gate apparatus. Next they installed sheet-piling to aid in setting the forms for the concrete collar that will eventually hold the new tide gate in place.

The replacement gate is more salmon friendly.

“The old gate was hinged at the top and automatically opened up-and-down with the tides,” said Frazier, “the new gate is different in that it swings horizontally.”

Frazier said fish biologists have discovered that a tide gate that swings from side-to-side moves more slowly in the water than one that swings up and down.

“That means less fish are injured and the slower movement gives the salmon more time to swim around the gates,” he said.

The Corps plans to install one more tide gate near the refuge office.

“The last gate is near the east end of Steamboat Slough Road,” said Frazier.

Each tide gate installation takes about eight weeks. The Corps should be finished sometime in November or December.