HUDSON – Reducing salt in New Hampshire waterways while keeping roadways safe in winter is one reason Nashua Sand and Gravel owner Todd Hansen created perhaps the state’s first private salt brine production facility for plow trucks.

But it’s not the only reason: There’s also business.

“We have customers from three states, because this isn’t available for contractors anywhere else,” Hansen said during a recent tour of his facility on Route 102 in Hudson, which began operation this fall. “We just had a truck come from Portland, Maine.”

Hansen decided to get into the brine business this year partly because winter is slow for the sand and gravel business. His operation, at rented space at Tamarack Landscaping near the Londonderry border, cost him about $125,000 to set up, Hansen said, adding that this winter will determine whether he’s a genius or a joker.

“We’ll find out,” he said.

Hansen’s brine system has holding tanks that can handle as much as 100,000 gallons of water, plus pumps and tools to mix up the brine.

Hansen said the mix of water and salt in brine is carefully measured to lower that freezing point as much at possible. And I do mean carefully: He uses a hydrometer to get “in the ballpark” while mixing salt and water, then a refractometer – which measures the refractive index of water – to get as close to 23.3 percent as possible.

Private plow truck operators can buy a nozzle system that hooks onto the back of pickup trucks, slipping right into the trailer hitch and powered by the truck battery, for as little as a couple thousand bucks. The system Hansen sells has four sprays, each with three nozzles – called fan, 3-stream and pencil – like a fancy shower head. They rotate into position depending on the job that needs to be done, which in turn depends upon the air temperature, ground temperature, humidity and what the weather will be like in the next few hours.

A tote of brine, 275 gallons, costs about $100. It fits in the bed of a full-sized pickup (although it weighs 3,000 pounds, so the suspension better be good), allowing them to spray as they plow, just as many now release dry sand.

Communities have been using trucks to put down road salt to make roads safer in winter for decades. Why replace it with brine, which is a mix of roughly three-quarters water to one-quarter salt?

To be more effective while using less salt, that’s why. This can produce environmental benefits and cost savings and, since last year’s shortage of road salt may be repeated, can make the difference between running out and having your supplies last all winter.

Salt, as well as other chloride chemicals, is effective on icy roads and walkways because it binds with water molecules and makes it harder for the molecules to create ice crystals – that is, it lowers the freezing point. For example, a wet sidewalk will be icy when it’s 30 degrees, but if enough salt is applied to lower the water’s freezing point to 29 degrees, it will merely be wet.

Salt in a brine solution is more effective partly because it can come in contact with more water molecules and break the all-important bond between ice and road surface. The proper brine solution (23.3 percent by weight) can reduce the amount of salt needed for a given surface by as much as one-third, although the numbers are tough to pin down.

“There are a million studies about this,” said Hansen, pointing to a host of chemical mixes sold as alternatives to salt.

New Hampshire is among many states urging a switch to brine as part of various techniques to reduce salt use, largely because road salt tends to end up in waterways, killing fish, insects and plants. Problems with salt runoff into creeks has even delayed the I-93 widening.

Salt also corrodes concrete and causes metal to rust, which can do a number on bridges.

The state and some cities already do some brine spraying as part of their storm work, but until now it hasn’t been on option for the hundreds of individuals who plow parking lots, driveways and private roads around the area.

To get more of those people thinking about cutting salt use, the New Hampshire Department of Transportation has created a voluntary salt applicator certification, to train private plow truck operators about the best way to do more with less salt. In October, it held a Salt Symposium at which hundreds of individuals showed up to learn how to do the job better.

Hansen hopes they’ll all become his customers.

Switching to brine isn’t the only way to cut back. Many places are doing a pre-storm coating on roads that can be more effective than applying salt after snow or freezing rain has started to fall. In the Midwest, Hansen said, some bridges are equipped with brine sprayers that will pre-apply the solution when a storm is coming – no need to send out trucks.

There are also other chloride compounds that can lower freezing points even more than road salt, although they are more expensive; and even without a brine solution, pre-wetting salt makes it more effective because the granules stick to the icy road instead of bouncing off.

“There’s a lot of work being done on this subject,” he said. “It can be complicated.”

David Brooks can be reached at 594-6531 or dbrooks@nashuatelegraph.com. Also, follow Brooks on Twitter (@GraniteGeek).