The City of Walla Walla Public Works Department is working on locating and fixing pavement damaged by frost heaves. Frost heave occurs when water in the soil freezes and expands. This expansion is very powerful and can move or destroy what had seemingly appeared to be solid construction.
The amount of precipitation the area received between December 2016 and February 2017 was comparable to the amount of precipitation the area received between December 1995 and February 1996, during which time there was significant flooding. From December 2016 to February 2017, the area received 5.75 inches of rain and 34.1 inches of snow. From December 1995 to February 1996, we received 9.43 inches of rain and 25.3 inches of snow.
Because we had above average amounts of precipitation and endured a rare period of sustained, below-freezing temperatures, the soil froze to a much greater depth than usual. The average low in December 2016 was 22.8 degrees, which is 5.6 degrees below the average. In January 2016, the average temperature was 21.5, which is 14 degrees below the normal average. In addition, the overnight low temperatures in December and January were below freezing on all but five nights.
In the past, frost heaves popped up during the course of the normal freeze-thaw cycle. The Public Works Department allowed the soil to dry out and settle, and then crews repaired the pavement. This year, frost heaves have been far more damaging to the streets than in the winter of 1995-96. To date, crews have identified 72 areas of pavement damaged by frost heave. They are prioritizing the list and will begin working on the top seven locations. Those areas include the following:
- Bridge St. from Alder St. to Ruth St.
- Howard St. from Alder St. to Pleasant St.
- Maple St. from 1st Ave. to Catherine St.
- Cherry St. from 5th Ave. to 6th Ave.
- Ankeny St. from Whitman St. to Pleasant St.
- Sycamore St. from Whitman St. to Pleasant St.
- Division St. from Walla Walla Ave. to Isaacs Ave.
Since plants are not making hot-mix asphalt until late March or early April, repairs will be very temporary. Crews will dig out 12 to 18 inches of street surface and saturated subsurface material. They will partially fill the hole with a foundation of larger rock, which will not sink into the wet soil, and top it with finer rock. Once hot-mix asphalt is available, crews will pave over these areas. Until temporary repairs can be made to all of the spots damaged by frost heave, we encourage citizens to avoid driving over them. To report frost heaves or other areas in need of repair, call the Street Division at 527-4363 or email .