Pilot project planned for chip seal alternative | City brief

Mar 05, 2014

The council is paving the way for a pilot project to try an alternative to chip seal when maintaining city streets.

Mukilteo City Council on Monday authorized Mayor Jennifer Gregerson to sign an interlocal agreement with Snohomish County to go in on BWC paving projects.

BWC or “bonded wearing course” is a paving alternative that is topped with a thin layer of asphalt.

With the interlocal agreement, the city can include its paving projects in Snohomish County’s Overlay Program each year, according to city staff.

The agreement allows Mukilteo to partner with the county in the design, engineering, traffic control, grinding, overlay and other pavement-related work on its projects – and at the same pricing structure.

As such, the city will receive competitive bids for its city projects from a contractor, staff said.

After residents complained, the mayor halted the city’s Pavement Preservation Program to find alternatives to chip seal that work well and look good.

Adopted by the council in 2007, the program called for the chip sealing of streets on a rotating schedule. About 20 miles of streets have been chip sealed. There are still 42 miles left to treat.

The mayor’s new Preserving Our Streets plan includes trying BWC in pilot projects on 88th and 92nd streets, followed by looking at other alternatives and hosting open houses.

Chip seal is estimated to last 7-10 years. It involves laying a layer of oil, covering it with about 3/8 inch of rock chips and seating them with a roller, then sealing it with another layer of oil. Another black seal helps smooth out the street.

BWC is estimated to last 10-20 years. It also starts with a layer of oil but is then capped with 3/4 inch of asphalt.

With the asphalt layer, BCW provides a smoother ride, there is no lose rock or dust, and it can be open to traffic in 10 minutes, staff said.

Asphalt costs $26 per square yard, whereas chip seal is around $4.68 a square yard and BWC is about $7.55.

-Sara Bruestle

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