Santa Rosa eyes restoration of Colgan Creek
An ambitious but long-delayed bid to restore an urban creek in southwest Santa Rosa to a more natural state took a key step forward this week when the city awarded the construction contract for the first phase of the project.
The Santa Rosa City Council on Tuesday approved a $1.6 million contract to rebuild a 2,250-foot section of Lower Colgan Creek near Elsie Allen High School.
The $16 million project has been 15 years in the making. It aims to breathe life back into a stretch of creek that for decades has been confined to an inhospitable concrete flood control channel.
"It's absolutely exciting," said Rita Miller, an engineer in the city's utilities department. "It's really an important creek restoration project and we want the community to know that we're moving forward with it."
City officials were heartened to see the winning bid, by Team Ghilotti of Petaluma, come in 42 percent below the city's estimate.
The city's civil engineer on the project, Greg Dwyer, was amazed at how aggressively the bidding was on the job, with 20 construction firms analyzing the project and 10 submitting bids.
The drought has allowed many contractors to work through their backlogs during the winter months, leaving them with far fewer projects lined up for the spring and summer, Dwyer said.
"That's why they were so hungry," he said. "The drought's a bad thing, but in this case it works out for us for construction."
Work is expected to start in mid-June and run through mid-October, the only time when major construction in creeks is generally permitted. Construction will take place along Bellevue Avenue from Dutton Meadow to where the creek crosses Bellevue.
The full project covers a 1.4-mile stretch from West Victoria Drive near Hearn Avenue to the high school. The work to restore one of the city's most polluted creeks has been broken into three phases. Other sections could take years to complete and only if additional grant and other funds can be identified, Dwyer said.
Before major work begins this summer, any fish will be removed from the creek and relocated. Then the creek will be diverted through a large culvert and the concrete walls of the flood channel will be removed, Dwyer said.
The streambed will then be widened onto adjacent property, giving the creek room to roam. Allowing the creek to meander is important because it slows the waterway down, providing better habitat for aquatic life and improving water quality. It also will increase the creek's capacity to handle a 100-year flood event.
"Flood plains are nature's way of dissipating energy," Dwyer said.
The goals of the project are similar to those of the Prince Memorial Greenway along Santa Rosa Creek, but with a simpler design aesthetic, Dwyer said. The project represents the current best practices in creek restoration, which eschews concrete walls in favor of natural materials like willows for bank stabilization, he said.
A series of pools will be constructed to create aquatic habitat and replace a concrete barrier to fish near the Burgess Avenue bridge. Large logs will be anchored in the creek bed to catch debris and mimic natural snags that create variation in the creek course and depth.
Thousands of native plants, many specifically designed to shade and cool the creek, will be replanted throughout the area. This form of bioengineering is complex and required hydrology studies to ensure the project struck the right balance between habitat creation and flood control, Dwyer said.