CENTERVILLE -- A new dam is expected to have a major impact on 181 homes formerly within a 100-year flood plain.
This week, officials sent a letter to those affected residents informing them they are no longer in a flood plain. City Manager Steve Thacker explained that the city has had the flood plain map amended by the Federal Emergency Management Agency, and it was made official Aug. 23.
With that amendment, the area was changed to a 500-year event, meaning that any year there is a 0.2 percent chance the area will be inundated with debris.
Now, residents can contact their insurance holders to have their premiums changed. Before, Thacker explained, some people were paying $400 a year, while others paid up to $4,800 for homeowner's insurance because of the former designation.
"We estimate that's $200,000 a year for those homeowners," he said.
Eliminating those premiums and improving safety were possible due to the completion of the Centerville Canyon Debris Dam project. The project was completed via a partnership between Davis County and Centerville.
Completion of the dam is expected to benefit downstream property owners in two significant ways, according to city reports. The first is the protection of life and property that it provides.
However, officials say that many will also benefit financially as the FEMA hazard map is revised and homes are removed from the regulatory flood plain, thereby eliminating the requirement of flood insurance.
Talk of this project began many years ago.
In 2005, the first estimate for the project placed it at $7 million. That's when the county and city decided to team up their resources and work with the Utah Geological Survey office for a study to determine the magnitude of the potential threat.
The study was completed in 2009. Initial thoughts to build a 55-foot-high structure with a 160-foot crest length were deemed as not workable because the proposed 12,000-square-foot structure was too high, potentially displacing a popular foothill path and bridge as well as downstream vegetation and impacting downstream artifacts.
Officials were able to come up with a new design that reduced the footprint by 40 percent and lowered the cost to $2.15 million, according to a city report. The length of the canyon impacted was also reduced to less than 200 feet.
This plan involved a 12-foot-high debris rack.
The project was included on the Davis County Flood Control capital improvement plan. It was completed in June by Bowen Construction of Centerville. Geo-strata of Salt Lake City provided the geotechnical engineering.
Final construction cost was $1.85 million. The city paid $240,000 for all engineering fees and the application/revision of the flood plain maps.
"This is fantastic for the city," Thacker said. "The county really came through as an excellent partner in this."
But, Thacker added, the county has been very helpful and a good partner on several flood control projects in the city during the last few years.
"This is just the most recent," Thacker added. "We appreciate them very much."