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Failing chipseal will be repaired
beginning in May weather permitting
By Sharon Kivisto
posted 2/22/2007
A combination of factors caused the poor condition of the chipseal applied to roads on Lopez and San Juan Islands in 2005 and 2006, according to Public Works staff. The problems have been identified and the roads will be fixed using one of three different methods beginning as early as May 15 weather permitting.
The chip rock did not embed properly in the asphalt emulsion for several reasons. The aggregate, while it met specifications, was too big. It measured as 5/8" by fitting through a screen, but it wouldn't have qualified if measured as a cube - in other words some of the pieces were long and skinny.
The best way to make sure the aggregate is embedded properly is to roll it three times. The county would need to purchase more equipment in order to do so. Speed is also a factor. Slower moving vehicles help embed the rock into the emulsion, faster moving traffic causes rocks to roll out of the emulsion.
The emulsion is temperature sensitive and should be applied between May 15 and August 15. The work in 2006 was done after August 15.
In order to make sure the chip seal problem is resolved, Public Works staff consulted with other county's road departments. Many of them have modified their approaches in the past ten years as the emulsion technology has changed, according to the report presented to the county Council Tuesday, Feb. 20, 2007.
The Public Works Dept. will use the following methods to repair all of the 2006 chipseal work and some of the 2005 work:
- Fog Seal Only - application of thin coat of asphalt on top of existing surface. This will help with rock retention.
- Fog Seal with a Choke Rock - as above with sand or 1/4 " crushed rock applied on top of the asphalt. This will help with rock retention and reduce apparent roughness.
- Chipseal with smaller aggregate and Fog Seal - this will provide a new surface with significantly reduced apparent roughness. It has not yet been determined if this can be accomplished in one chipseal pass of if two, a pre-leveling and a wear course, are required.
The asphalt emulsion for this year's chipseal will be purchased from Vancouver, Washington. The vendor will provide a distributor, an operator and an inspector. The operator and inspector will provide training for the county road crew. The low temperature emulsion requires a 40 degree F surface temperature to apply.
Since new equipment cannot be purchased in time for this year's repairs, it will be rented.
Chipseal? But the road looks okay!
By Joanruth Baumann
Manager of Programs and Planning
San Juan County Public Works Dept.
posted 06/07/05
The old saying "Pay me now, or pay me later" is especially true when applied to the life of road surfaces. You may not be able to see it but surfaces are constantly deteriorating, admitting water, loosening their bond with the ground and beginning to break apart. Sometimes you can see the cracking or sagging of the surface. Other times you cannot.
It's easy to see why a road section that is cracking or breaking needs some serious attention. It's less obvious why a section that looks pretty solid would need another chipseal surface applied. The answer lies in the economics of the types of repairs a deteriorating road needs and how the costs might differ.
Over the life time of a road, without care, it will deteriorate through a predictable set of conditions. After use for about 40% of its useful life, a road might still look good but will be starting to break down in minor ways. If you chipseal the road at this time, it will cost about $.70/sf to bring it back to a like-new state. If you let the road go until it has consumed 70% of its useful life and the cracks and bulges are becoming obvious, the cost to repair and restore the road rises to about $3.50/sf. If you wait longer, say until it has used up 90% of its life and the potholes are hard to ignore, this road has sustained enough damage under the surface that it has to be reclaimed - that is scratched up and resurfaced with recycled material. This can cost $6.15/sf to do. If, on the other hand, if you let your road go until it has no life left in it, it can take about $14.00/sf to dig up and reconstruct the road.
Our goal is to get our roads up to a good condition and then keep them there. By chipsealing once every 7 or 8 years, we save the County multiple times that amount down the road. (No pun intended!) We could never afford to maintain our roads if we waited until they were all in need of repairs. We think this is the smartest dollar we can spend for the County.
So we make the most of the dry summer months (the only time chipseal can be applied) and spend three months rotating through the islands, tending to roads that are reaching that magic 40%. We try to minimize inconvenience and sweep it up after the needed three to five day wait. Thanks to all of you who took the delays this summer with good humor and made our jobs easier with a smile.
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