By Phil Dodd
As Montpelier’s streets slowly recover from a major outbreak of potholes, city officials are considering new methods they could try in future years to make better and longer-lasting patches, including one technique already being used in larger Chittenden County municipalities, in Waterbury, and soon, Stowe.
This 2019 pothole season in Montpelier was one of the worst in years, if not the worst. Streets and roads in other towns in Vermont also suffered. For example, Charlie Woodruff, Waterbury’s public works director, said it was “a terrible year for potholes and frost heaves.”
Currently, Montpelier uses looser “cold patch” asphalt in the winter and early spring to fill potholes temporarily, but that material is difficult to work with in cold weather and can only be put in place when the potholes are not filled with water or ice. Moreover, cold patch only lasts a few weeks at best, requiring some potholes to be filled repeatedly during pothole season.
Once warm weather arrives and the local asphalt plant opens, Montpelier mostly shifts over to using “hot mix” from the asphalt plant. Hot mix creates a much longer-lasting patch, sometimes lasting several years.
Montpelier Public Works director, Tom McArdle, said pothole repair has been slowed this spring by the rainy and cool weather. The rain leaves potholes full of water, which prevents filling, and hot mix can only be applied at 40 degrees or above. “You have to have good conditions for a lasting patch,” he noted.
McArdle said he would like to reduce the amount of cold-patching the city does and that the easiest way to accomplish that is to repave more streets. “The more we can spend on rehab projects, the less time and money we have to spend on cold patch,” he said. For example, he said, last year there were a lot of potholes on College Street, but after repaving last summer, “there were no potholes this year.”
Paving roads is expensive, however, so unless and until the city’s repaving budget is raised, McArdle is also looking at better patching techniques. “One thing we will try in the future is to use our Vactor to suck water and foreign material out of potholes before patching,” he said.
The Vactor is essentially a big vacuum that is normally used to clear storm drains and sewers. McArdle called it “the most versatile piece of equipment we have in our inventory.” Sucking water out of the potholes would allow for quicker patching and perhaps a better seal, even with cold patch.
The other technique the city is looking at would involve buying a portable “hot box,” fueled by propane or oil, that can be used during cold weather to heat up cold patch—making it easier to work with—or to create hot mix by recycling old asphalt. The hot boxes, sometimes call hot patchers, can be put on a trailer or on the back of a truck.
McArdle said the price of such units—$20,000 to $30,000 or more—is “not out of reach.” But unless money can be freed up from the city’s equipment budget, McArdle said he will probably have to wait to make a request for a hot box in the budget that will be put together next fall and voted on in March 2020. If that happens, the hot box would not be in use until the winter and spring of 2021.
Waterbury has had a propane-fueled hot box on a trailer for a couple of years that the town uses primarily to heat up cold patch. “Heated cold patch lasts a little better,” said Woodruff. “You can get it into cracks and crannies better, and it lasts longer, although it is still a temporary solution. But there are no temperature restrictions like with hot mix, you just have to get the water out of the potholes.”
Another benefit of using the heated cold patch is that it easier to shovel out from the back of a trailer compared with the bed of a truck, he said. Waterbury also uses the hot box on cool days in the spring and fall when it gets hot mix from the plant and wants to keep it warm longer.
Stowe has been using its own jury-rigged system to heat up cold patch, but is trying to fit the purchase of a manufactured hot box into its current budget, according to Town Manager, Charles Safford. “We hope to have one by next winter,” he said. “We believe we’ll get better adhesion with heated cold patch when filling potholes.”
One company that sells the hot box systems is Viking-Cives of Vermont, based in Williston. Company salesman Mike Murray said the problem with using cold patch that has not been heated is that “it only lasts a week and then you have to go fill it again.”
He said he used to sell the hot box systems in the Midwest, where they are more common. “Burlington was one of the first places in Vermont that bought one. Then the units were purchased by nearby towns such as South Burlington and Colchester, and now the concept is spreading to places like Waterbury,” Murray said.
He noted Colchester bought a hot box trailer in part because of personnel issues. Their workers were getting sore shoulders from shoveling unheated cold patch out of a chest-high truck, he said.
Murray said that the hot boxes can be used either to heat up cold patch or create hot mix. “You can mix some virgin asphalt and chunks of recycled asphalt and then have a timer to start melting the asphalt in the night so it is ready to go in the morning.”
McArdle said Montpelier has quite a bit of recycled asphalt at the stump dump which it could use in a hot box to make hot mix when the asphalt plant is closed. That plant does not open until mid-April because that is the earliest that temperatures allow road paving to occur in Vermont.
A hot box—in addition to the use of the Vactor—would hopefully improve the pothole situation in Montpelier, but unless something changes, it looks like it could be some time before the city might purchase a hot box.
Meanwhile, city workers are continuing to patch the many potholes that opened up this past winter and early spring. McArdle said progress is being made, but added “we’ll be at it for a while.”