The City of Burien will launch a "Slurry Seal" road maintenance program on Aug. 7 which will close various roads for a day at a time as the work is done. What is it? The city said,Slurry Seal is "a mixture of fine aggregate about one-eighth to one-quarter of an inch (at maximum size) and emulsified asphalt that is "painted" on residential roads. This preventive maintenance preserves the life of existing asphalt and "coats" it from the long term effects of continual water penetration and sun. Think of it as a coat of paint on the sidings of your house or deck treatment for extending the life of your brand new deck. Slurry seal is a cost-effective roadway treatment very similar to that previously mentioned and provides a new wearing surface and it usually lasts three to seven years on top of the actual life of the pavement.

Slurry seals are typically applied during warm, sunny weather to accelerate the curing process. The application process requires a one-day road closure."

The process is a fraction of the cost of asphalt overlay or complete road reconstruction. 

According to the city:

"As an example for 1000-feet stretch of residential street:
Slurry Sealing - $ 12,000 (engineering and construction costs)
Asphalt Overlay - $120,000 (engineering and construction costs)
Road Reconstruction - $500,000 to $600,000 (engineering and construction costs)"

They say the process extends the life of streets in average to fair condition by some three to seven years depending on traffic and conditions. Residents may notice that the road surface is initially not as smooth but street sweepers and normal traffic will over the course of a year result in a much smoother and long lasting surface.

They note that residents will be notified via postcard of impending street closures and "Residents within the project area will receive information in several phases. First, project information will be sent to residents in late April. Next, residents will receive additional mailers such as a postcard of who the contractor is and what date the overall project will begin. Third, residents will receive door hanger reminders at least 72-hours before work on their respective streets are to begin.
On the day of work, the contractor will make one last effort to contact residents whose cars are within the immediate work area. Also, signs will be placed along the roadway reminding residents of the temporary no parking areas.
Driving on the fresh slurry will damage your car! Please allow for it to dry in 4 - 6 hours. If you drive on the fresh slurry you may be held responsible for the cost of reapplying the slurry. Please plan ahead."

They offer more information on the project here.