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1. What is a seal coat?

A seal coat consists of sealing existing cracks in the pavement, adding a layer of asphalt binder, adding a layer of small rock, and covering the rock with an asphalt coat. This process usually happens in 3 steps as shown below.

• Step 1: Seal the existing cracks in the pavement ("crack seal")
  • During this step, all small and large cracks in the existing pavement surface are routed and filled. Routing is the process of sawing a crack so that it is wide enough to fill with the sealing material. Generally, this process is completed in a few hours per block depending on the amount of cracking that needs to be sealed. Flaggers or other traffic control may be present during crack seal activities.
• Step 2: Place asphalt and rock layers ("chip seal")
  • After the crack seal material has set up (generally a few weeks or months after crack sealing), the chip seal process is applied to the pavement surface. The chip seal consists of adding a layer of asphalt binder ("tack") to the pavement surface a few minutes ahead of adding a layer of small rock. The rock is then compacted with rollers following closely behind the seal coat operations. Flaggers and other traffic control will be present to direct traffic around the chip seal operations. Traffic may drive on the new surface immediately after rolling is completed.
  • Excess rock will be swept up with a street sweeper a day or two after the chip seal operations are complete.
• Step 3: Cover rock with an asphalt coat ("fog seal")
  • The final step of a Seal Coat project is to add an asphalt coat called a "fog seal" to seal in any loose rocks to prevent them from coming loose. Prior to the fog seal being applied, the street will be swept again by a street sweeper to pick up any remaining loose rocks. The fog seal generally takes about 30 to 60 minutes to dry before traffic is allowed to drive on it.

2. Can I get in and out of my driveway while they are working?

Generally, you will be able to get in and out of your driveway at all times except for the following times:

• Between when the asphalt binder layer is applied and the rock is compacted (up to 15 minutes of delay)
• After the fog seal is applied, there will be a 30 to 60 minute period where you will not be able to access your driveway until the fog seal has dried

3. Why does the city do seal coat projects?

Seal Coat projects are one component of the city's comprehensive pavement management program. Pavement surfaces tend to wear out much faster than the other components of a street (such as curbs, sidewalks, and utilities) due to the impacts of heavy vehicles. Seal Coat projects are generally reserved for when a pavement surface is in relatively good condition and is intended to keep the pavement in good condition. If a pavement surface has a number of cracks but is otherwise in good condition, a Seal Coat is likely still a good maintenance activity to prolong the life of the street.

4. How long do seal coats last before they need to be done again?

Seal Coats generally last 7 to 10 years or more depending on the condition of the pavement underneath.

5. Why do seal coats when mill and overlays last longer?

There are a few reasons to consider Seal Coats instead of Mill and Overlays:

• Seal Coats cost about a third of what a Mill and Overlay project does or about one-tenth of a Full Depth Reclamation.
• Seal Coats are effective at preserving roads that have many cracks. Cracks typically will reappear on a Mill and Overlay pavement within a year or two and require additional crack sealing at that time.
• Seal Coats are good for preventative maintenance. Mill and overlays and full depth reclamations are typically used reactively to counteract known issues.

6. Aren't seal coats messy, won't rocks get up in my yard or elsewhere on my property?

It is true that seal coats are "messier" than other types of maintenance projects due to the nature of using loose rocks as a pavement surface. However, the loose rocks are generally confined to the pavement surface or the curb area and should not be put in your yard. The loose rocks are swept up twice after the chip seal process is complete, one time a day or two after the chip seal process and another time about a week after the chip seal process is complete. Any loose rock in the street should be picked up during one of those two sweepings.

7. Will the loose rocks chip my windshield?

It is very unlikely that any loose rocks will chip your windshield due to a few different factors. First, we usually only use seal coats on lower-speed streets which will reduce the ability for rocks to become projectiles to be sent toward another car's windshield. Second, the rock used for the seal coats is only about one fourth inches in diameter, which won't cause much damage if it does hit your windshield.

8. What types of streets are good candidates for seal coat projects?

Generally, seal coats are good for streets that are already in good shape that we want to keep in good shape. Seal coats can be used on streets that have a decent amount of cracking already as long as the cracks are sealed with the seal coat project. Pavement that has wide cracks, "alligator" cracking, consistent large potholes, or surface spalling (pavement that is losing its "smoothness") are probably not good candidates for Seal Coats and would instead benefit from a mill and overlay or a full depth reclamation.

9. How is parking affected by seal coat projects?

Parking will be limited at times during a seal coat project so that the contractor can complete the work effectively. "No Parking" signs will be posted at least 48 hours in advance of parking restrictions going into effect. When the parking restrictions are in effect, vehicles still parked in the construction area may be subjected to ticketing and/or towing. We will try to contact the vehicle owner(s) if we find any vehicles still parked on the street during parking restrictions.

Parking restrictions may be posted for the following work:

• Crack sealing (usually in effect for 1 to 2 days)
• Seal coat (usually in effect for 1 to 2 days)
• Fog seal (usually in effect for 1 to 2 days)