Sedgwick County has had outdoor sirens since the 1950s, when residents feared air raids and nuclear bombs as well as tornadoes. But the sirens will become obsolete unless the county spends up to $1.5 million to update them by Jan. 1, 2013, county commissioners learned Tuesday.
None of the receivers on the county's 101 sirens is capable of interpreting a new narrowband signal required by the Federal Communications Commission, said Randall Duncan, the county's emergency services director.
The most expensive option, upgrading to digital, would allow the county to target a specific area where the storm threats are most severe, instead of sounding sirens across the whole county, as it does now.
"We could specifically target in on the area of warning, plus we would leave alone the businesses and other economic concerns outside of the area of warning without interrupting," said Duncan, speaking at the weekly meeting of commissioners and county staff.
The county now uses a central transmitter. A digital update would give each siren its own transmitter and receiver. That would allow the county to activate only devices inside areas where the National Weather Service considers a storm to pose the most severe threat.
In the past, some county commissioners have questioned whether specific warnings are preferable, contending that people could drive into dangerous areas if they don't hear a siren near them.
The digital sirens also would include sensors that would report back to the county on the siren's performance. The county now relies on residents to report whether sirens in their areas sounded or not, and those reports aren't always reliable, Duncan said.
A digital system would cost $850,000.
Commissioners could choose to update the analog system sirens now in use at a cost of about $300,000, Duncan said.
An analog update would allow the sirens to "hear" the new signals, but would not give them new capabilities, Duncan said. The county would have to continue to rely on feedback from Wichitans to determine how the sirens are performing.
Either way, Duncan said, the county would need to spend an additional $700,000 to replace the sirens' "noisemakers."
Currently, 79 of the 101 noisemakers are obsolete because some of their parts are no longer made, he said.
The County Commission last year approved $857,300 to update the receivers to digital. But the project was put on hold for more deliberation.
If the county does nothing to upgrade its sirens, it will face a substantial cost to dismantle the system, Duncan said.
County staff will study the matter for a couple of months before putting it on the commission's agenda.