JACKSONVILLE — Plans to notch the city's reservoir dam passed a big hurdle when the U.S. Army Corps of Engineers ruled last month that sediment studies to determine chemical contamination are not required, says the project's planner.
Savings without the study requirement will be in the tens of thousands of dollars, said Scott English of Ashland, whose Northwest Biological Consulting firm is doing design work for the city.
"I think primarily one of the reasons we weren't required to do any more is that this is not an industrial area," said English. The fact that the reservoir is "not in an urbanized area makes it a lot easier to make this call."
Jacksonville is under pressure from the state to remove the dam, which has been labeled a hazard for people and property below it on Jackson Creek and is likely to fail in a major flood. The City Council has set aside $50,000 for studies on breaching the dam and $150,000 toward the work. The dam was built in 1912 but hasn't been used for water storage since the 1950s.
"It looks like we have passed a milestone on the sediment evaluation," Joe Sheahan, a project manager with the Corps, wrote to English in an email. One of the big issues will be how to control sediment moving in the event of a flood, he added.
"The next step is more detailed surveying and engineering design for breaching to the extent necessary to restore the creek," said English.
The Corps of Engineers and the Oregon State Division of Lands will need to issue joint fill and removal permits for the process after studies and reviews by multiple state and federal agencies.
"You really have to involve a lot of different agencies plus stakeholders as well," said English. He expects public meetings on the process and presentations to the City Council.
A project description calls for removing about 30,000 cubic yards of sediment and rock, and using some of the material to restore the natural flow of the creek from the dam base to the natural channel upstream. Excess materials would be placed in an adjacent quarry, where the rock for the dam was originally mined.
The Corps' Portland Sediment Evaluation Team determined that no sediment testing is necessary after reviewing a report submitted in November by English. The Corps found that the reservoir site met criteria excusing it from testing.
Under the standards, more than 80 percent of the material must be sand, gravel or other inert materials in areas of high current with less than 0.5 percent total organic compounds.
The project area is sufficiently removed from sources of pollution that could contaminate the sediment, and current and historical land uses would not contribute to contamination, the team determined.
The restored channel and reservoir area would be graded, shaped and planted with native vegetation to create a riparian zone and stabilize sediments.
"It's a fairly complicated process to remove a dam, so simple solutions may not always work," said Sheahan.
Sheahan said he is looking for basic designs at this time, rather than spelling out what must be done.
"They may come up with an innovative process within the operating budget they have," said Sheahan.
Studies and approval might be accomplished by summer, said English, but funding for the project is not certain at this time. Work must be done during the creek's dry season.
The reservoir is located 1¬1/4 miles west of Jacksonville on Reservoir Road, in the city's Forest Park.
Tony Boom is a freelance writer living in Ashland. Reach him at firstname.lastname@example.org.