By Sharon Michael, The Chronicle, 4/9/98
A draft report now circulating among county and city officials detailing Pacific International Engineering's proposed multimillion-dollar solutions to Twin Cities flooding will be available to the public by the end of the month.
In earlier presentations before local government officials, the consulting engineering firm demonstrated a specially designed computer model that uses actual data from five major floods in the last 26 years to test conceptual solutions to area flooding.
PIE project manager Albert Liou constructed a sophisticated model of the Chehalis River watershed that duplicates past floods and forecasts river levels under various storm conditions.
The model also allows engineers to test proposed flood-control solutions by "raining" on the model.
It took Liou eight months to perfect the model, which also can calculate the effect of adding fill in the flood plain and measure the influence of other development activities.
"You've got a good tool," PIE manager Harry Hosey told Lewis County commissioners in January. "It simulates reality and provides good results."
Using the model, PIE consultants designed structural changes they believe would "virtually eliminate flooding" in the basin:
Excavation under Centralias Mellen Street Bridge and overbank excavation at other points along the Chehalis River north and south of the bridge.
Modifications to the Skookumchuck Dam, including installation of an inflatable rubber gate on top of the dam to increase reservoir capacity and larger outflow structures to allow for faster release of stored water.
In combination, Hosey said, these modifications could reduce the flood level at Mellen Street from 7 feet to 1 foot. Hosey said a 4-foot flood reduction at Mellen Street would keep Interstate 5 from flooding.
For several days in 1996, portions of I-5 between Centralia and Chehalis were under several feet of water. Closure of the main ground transportation link from Canada to Mexico cost an estimated $80 million a day. Flooding also closed I-5 in 1990.
Flood damage to residential and business properties totaled nearly $20 million in 1990 and $30 million in 1996. Flood victims qualified for Federal Emergency Management Agency reimbursement of up to 75 percent of damage. State emergency funds paid for up to 12 percent of property losses.
PIE's tentative flood control projects show the kind of flood level reductions that could be achieved, Lewis Countys Bob Berg said. But he warned it is "important to keep the level of expectation reasonable.
"We're not there yet," Berg added.
Completing the computer model and testing conceptual solutions is just phase one of the project.
The $550,000 spent to date has paid for a detailed survey of the watershed, and for a state-of-the-art computer model to test proposed structural changes to waterways and dams.
An additional $600,000 in transportation money allocated by the Legislature will be used for public meetings, environmental studies and preliminary design work.
Berg said public review of the project proposal is critical.
"Please look at it with a discriminating eye - even a jaundiced eye," he urged. "If this does not have public support and public involvement, it won't work."
Duane Bryant, Lewis County Flood Control Zone citizens advisory committee chairman, and Ilona Petersen, Chehalis Subzone committee chairwoman, declined to comment on PIE's proposal until they see the published report.
Phase two of the project would include developing engineering plans and obtaining required permits, if commissioners approve moving beyond the planning phase. County engineer Pete Ringen said county projects typically are approved in stages.
PIE's proposed engineering solutions are fairly simple, but the 900-square-mile Chehalis River watershed is complex, Berg pointed out.
"There is a huge concern that we don't pass our problems downstream," he emphasized.
Construction of the proposed projects is estimated to cost about $80 million. But Hosey and county officials say the proposed flood-control measures could be an alternative to spending $60 million to $80 million in state and federal transportation money to elevate I-5 above the high water mark.
"Everyone we've presented this to has said this may work," Berg said.
Berg and Hosey have demonstrated the model to legislators and Lewis County's congressional delegates.
But because the proposed project doesn't fit neatly within the jurisdiction of any single federal agency, Berg and Hosey have been shuttled from one to another to make their financial appeals.
"Government has got to think outside of boxes," Berg added. "We need federal up-front money and federal commitment."