City saves time, money on winter snowplowing

After record snowfalls in early January, South Bend residents have been doing extra shoveling and extra worrying about forecasts for the rest of the winter season.

But City of South Bend snow-removal crews are addressing seasonal snowfalls in a more proactive, cost-efficient way. The new approach involves cooperative purchases of road salt with the State of Indiana and other local governments, along with the conversion of a small portion of the granular rock salt into liquid salt brine.

Time- and money-saving salt brine is processed at one of the City of South Bend’s Street Department buildings.

In January 2009, the City’s Street Department began working with a newly installed salt-tank manufacturing system to make salt brine from a mixture of granular rock salt and tap water. At the time, salt prices had been rising, so a cooperative governmental purchase of road salt enabled the City to buy a large quantity of salt at $54.67 per ton, compared with market prices reaching $150 per ton.

But cost-saving efforts went one step further: The City sought to prolong the salt supply by converting a portion of it to brine, a liquid mixture of 23.5 percent rock salt and water.

Where 1 ton of rock salt covers 4 miles of street, that same amount of salt, when converted to brine, accomplishes the same results for 19 miles of streets — a nearly fivefold increase.

That estimate is conservative because studies indicate that 40 percent of dry salt placed on a paved road will bounce off the road.

The savings is further compounded in the means of application: Salt brine is applied proactively ahead of storms during “straight-time pay” periods, while road salt is applied on overtime pay during storms.

First-year results were dramatic. The Street Department conserved about 2,500 tons of salt in 2009 — an estimated cost savings of $140,000. The application of the salt brine in advance of storms also helped the department save nearly $12,000 in overtime costs, especially since the Street Department no longer needed to call in personnel after hours during light snowfalls. The salt brine is easier on the roads, less corrosive on bridge decks and less detrimental to the environment than traditional road salt.

The in-house system involves four 10,000-gallon tanks. Two tanks contain geomelt, a beet juice solution that helps increase the temperature of the brine application, enabling a faster melting time. Tests began in spring 2009, and the system was tweaked with more automation before final implementation in the winter.

Through testing, City crews discovered that a 70/30 solution of salt brine was optimal for the coldest temperatures. With sunshine, temperatures near freezing and a predicted light snow, the department can make an 80/20 mix that relies more heavily on salt brine (30 cents per gallon), rather than on geomelt ($1.88 per gallon).

“We’re the only ones in northern Northern Indiana, besides the state highway department, that can do this, because we have our own manufacturing tank,” says Sam Hensley, director of the Street Department. “We can mix it at any strength we want. The geomelt makes it hotter so it can melt faster.”

Most municipalities using liquid brine purchase a 70/30 mixture of salt brine to geomelt. With its own system, South Bend gains flexibility and saves money by choosing the mixture best suited for the conditions.

“Other municipalities cannot do that because they cannot regulate what type of mixture they want,” Hensley added.

Looking ahead, the Street Department is redesigning snowplowing routes to make use of new “wing plows” that will increase efficiency and save time.