Portions of Warm Springs Avenue and East Starview Drive remain closed until the slopes stabilize and the rock fall risk is diminished, the Ada County Highway District announced Monday.
ACHD crews starting removing fallen rocks on Starview Drive on Monday. If the road remains boulder-free in coming days, ACHD may consider at least a partial reopening.
Warm Springs Avenue, however, continues to shed rocks and cannot be considered for reopening at this time, ACHD’s Engineering and Maintenance departments concluded on Friday.
The highway district has hired a geotechnical firm to study the situation and provide options for interim steps and a long-term solution to the long-standing problem. A report is expected by mid-March.
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Several large rocks broke loose from the Warm Springs Mesa, forcing the closure of portions of Warm Springs and East Starview on Jan. 10.
Warm Springs Avenue is closed from Starcrest Drive to East Parsnip Peak Drive, and Starview is closed from Warm Springs to South Mill Point Lane.
During the closure, residents of the Mesa will still be able to use Starcrest and Windsong Drive to access the area.
Those needing to travel downtown from east of the Mesa will have to use ParkCenter Boulevard until further notice.
The rocks are likely falling because of the recent rain and thaw, which has destabilized the fragile slope where rocks often move in the spring, according to ACHD. The winter’s weather pattern – snow, followed by weeks of subfreezing cold, followed by rain and higher temperatures – is believed to have touched off a fresh round of erosion.
In January of 2015, Warm Springs was closed for two weeks between Starview and Starcrest after a 50-ton boulder fell onto the road. After a contractor removed a number of teetering rocks, ACHD crews placed more than 1,200 feet of concrete guard rail along two areas at the foot of the Mesa to block stones from getting to the road.