2020 Cape and Slurry Seal
The Cape and Slurry Seal Project is an effort on the part of the City’s Engineering and Maintenance Divisions to perform preventive maintenance on existing street pavements. The surface treatments; which include cape seals and slurry seals are all designed to extend the pavement life of each street. The work is less intensive than a reconstruction project, but more economical, which allows for a greater number of streets to be treated.
This year’s project includes a total of 225 street segments, consisting of approximately 27 centerline miles of roadway and covering 5.7 million square feet of pavement surface. The work is scheduled for the summer of 2020.
A portion of the project is being funded by a grant from CalRecycle. The grant not only contributes toward the improvement of City streets, but it also helps to promote the diversion of discarded rubber tires from the landfill. The rubber from scrapped tires is ground and mixed into an asphalt blend that strengthens the pavement sealants used in this project. The estimated number of tires diverted through this project is 26,000 tires.
Funding for the project also includes voter-approved funding from Measure B, Measure BB, and the Vehicle Registration Fee (VRF). The Alameda County Transportation Commission allocates these funds to local agencies for use on various transportation improvement projects including this one.
Anticipated Impacts on the Public
Temporary lane closures will occur when cape and slurry seal work is in process. Traffic flow may even be affected on streets adjacent to where the work is occurring.
Parking will be restricted on streets when cape or slurry seal work occurs. No parking signs will be posted in advance of the parking restrictions and advance notices will be delivered to nearby properties.
Work will occur in a series of activities. The sequence of activities may vary, but the following can be expected:
- weed spraying
- weed removal
- crack sealing
- base repairs/skin patches
- chip seal (cape streets only)
- slurry seal (all streets)
- restriping of traffic lanes
- curb ramp installations
Base Repairs and Skin Patches – Base repairs are localized repairs in the pavement where a portion of the pavement is ground out and replaced with new asphalt. Base repairs are usually performed in relatively small areas of pavement where pavement base is no longer supporting the pavement surface properly. A skin patch is used to level out portions of pavements where surface depressions exist.
Crack Sealing – Crack sealing involves placing elastic material directly into cracks in pavement. Water intrusion into pavement cracks causes pavement deterioration. Sealing the cracks prevents water intrusion from occurring and extends the useful life of the pavement. Prior to crack sealing, all cracks will be sprayed with herbicide to remove weed growth. Streets receiving a slurry seal will be crack sealed.
Slurry Seal – Slurry seals involve spraying a mixture of polymer modified asphalt emulsion, well-graded fine aggregate, mineral filler, and water on the pavement surface. It is used to fill cracks and seal areas of old pavements, to restore a uniform surface texture, to seal the surface to prevent moisture and air intrusion into the pavement, and to improve skid resistance. Streets that are in relatively good condition will be slurry sealed in order to preserve its condition.
Cape Seal – A cape seal is a thin surface treatment constructed using a two-step process. The first step involves placing a “chip seal,” which places small graded stone (chips) on a liquid asphalt blend that is sprayed on the pavement surface. The chip seal is rolled to embed the chips securely to the surface. The second step involves a slurry seal, which is applied on top of the newly applied chip seal (normally one or two weeks after). Streets that are in fair condition or worse will be cape sealed.
Curb Ramps – Part of the effort to maintain the pavement will involve improving the street intersections with new curb ramps. The intersections will receive new curb ramps if a sidewalk has no existing curb ramps in place or if the existing curb ramps were built under an older standard. Curb ramps will be installed after the placement of slurry seal.