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Division of
Engineering & Roads

1026 W. Broadway Ave.
Spokane, WA 99260-0170
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Market Street (Parksmith Dr to Farwell Rd) Closure Monday, April 11, 2016
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Road Maintenance Activities

Cement Treated Base Residential Slurry Seal
Standard Chip Seal Pre-Coated Chip
Fog Seal Crack Sealing
Grind & Inlay Program Dust Control
Patching Pothole Patching
Rehabilitation Asphalt Overlay Program
Gravel Road
Rehabilitation & Restoration


Dust Control

The unpaved roads of Spokane County inevitably generate dust during dry periods. In an effort to suppress these dust emissions and irritations associated with air born particles, Spokane County allows property owners and residents to contract for the application of County approved dust palliatives on County roads, at the homeowner/s or property owner/s expense. This can be accomplished by contacting an authorized contractor utilizing an approved dust suppression product. This expense is completely placed on the home owners and costs vary depending on road lengths and variance of prices between contractors.

Dust Control Season

The time frame for the dust control season varies year to year based on several factors such as weather and road conditions. The 2015 dust control season ceased on June 18th rather than the scheduled date of June 30, 2015 due to extreme fire danger.

For additional information or a list of approved contractors please contact:
Spokane County Division of Engineering and Roads (509) 477-3600.

Cement Treated Base

Spokane County began this process in 1999. The intent of these projects is to improve the underlying structure of the road and create an all season road. This process eliminates the closing of a road due to the freeze thaw season. This process decreases the high cost of maintaining these roads which are utilized frequently by heavy equipment.

This process involves a contractor pulverizing the existing asphalt in to a 3-inch minus material then adding dry Portland cement to the surface. This matter is then mixed with water to a depth of 8-10 inches. A 3 shot bituminous surface treatment is added to the road surface. This process does require that we close the road to local traffic only due to a curing time of about 2 weeks. Weight restrictions are in force during this period of time.

Residential Slurry Seal

Damaged areas are first crack sealed and repaired. A Type 2 slurry seal (a mixture of fine gradated rock with emulsified asphalt) is applied by a contractor. The slurry is applied by a squeegee off the back of a truck. The road is typically shut down for approximately 4 to 6 hours. The slurry material creates a sealant on the road and rejuvenates the surface.

Standard Chip Seal

Chip sealing is the most common resurfacing method in Spokane County. Chip Sealing is usually used to pave long stretches of rural roads, but has also been used on urban roads with success. Emulsified oil is applied to the road surface, with road chips added on top. There may be some minor delays during the application. This process helps seal the road and provides a new riding surface.  To view a map of scheduled chip sealing routes, please link to:  Chip Seal Status Map

Pre-Coated Chip

A new process that coats standard rock chips with 1% oil at the hot mix plant. These pre-coated chips bind together better than the non-coated chips when applied to the road with hot asphalt oil. We expect this method to use fewer chips and less asphalt oil. This road surface will produce less dust and fly rock for area drivers. The road can be swept and striped in the same day.

Fog Seal

This process is used to rejuvenate the asphalt surface which degrades and oxidizes with time due to environmental and other conditions. The fog seal is applied to the surface with a small amount of emulsified oil (50% diluted with water). The oil fills in the crevices and small cracks and helps to extend the life of the existing pavement.

Crack Sealing

To combat the effects of water penetration into the sub grade, Spokane County applies a flexible crack sealant into and over cracks that are ¼” wide or greater. Cracks are sealed before overlaying, fog sealing, or chip sealing a road. When the crack filler dries it leaves the crack sealed from any further infiltration, extending the life of the road a few more years or until the next scheduled repair or replacement. Arterial roads are evaluated yearly for crack sealing candidates.

Gravel Road Rehabilitation & Restoration

The rehabilitation process involves re-ditching, repairing or replacing culverts, fixing soft spots, shaping and in some cases widening the road. These roads usually receive 4 inches of new base rock and 3 inches of new top rock.

The preservation process involves regrading, light ditching and applying 2-4 inches of top rock to the existing surface. These roads are prioritized by traffic and need due to maintenance problems.


(Pavement removal and replacement) - When an area of road surface is damaged it is repaired and then a layer of hot asphalt mix and base rock area applied. The arterial roads are a priority. Roads to be chip sealed, fog sealed or overlay require these repairs.

Pothole Patching

This process involves removing debris, cleaning, adding new material if needed, and applying a temporary asphalt material. These patches are usually repaired at a later date with a permanent fix or are repaired during the next rehabilitation or preservation project.


This process usually involves a road that has failed structurally with the existing asphalt and base. It is also used to rehabilitate and pave existing gravel roads or rehabilitate an existing paved road to add capacity and correct safety issues. The depth of asphalt and base rock is determined by a pavement section design.

Asphalt Overlay Program

This process involves grinding some of the old asphalt off and relaying new asphalt. Spokane County overlays approximately one to two miles of road per year. This is used as preservation for our urban arterials.

Grind & Inlay Program

Old pavement is ground or removed to a depth of about two inches and replaced with new asphalt. The grindings (removed asphalt) are recycled for future use.

This process is used for residential roads that have too many defects to make it cost effective to apply a slurry seal. This process involves grinding the existing asphalt, freshening up the rock or sub-base, fixing major curb, sidewalk and drainage problems and then applying new asphalt.