Safe Digging Below at Below Zero Temperatures
Jim Zylstra Feb 02, 2013
When the busy summer months have passed, and we have survived the dog days of summer, we are soon surrounded with cooler temperatures, football and the spectacular colors that only fall can bring.
For those of us who live in colder climates, this comes to an end with Old Man Winter knocking on the door. With him, he brings snow, ice, nasty working conditions and frozen ground. Some of us go into hibernation, some head south, and then there are those who will face him head on. They strap on their coveralls and don their hats and gloves, they lace up their boots, there is still work to do.
Moving dirt has been around one way or another as long as dirt itself, but moving frozen dirt has always been a challenge. Hydro excavators with hot water are a good solution for this problem, particularly when digging in safety tolerance zones.
The vacuum excavation market exploded in the early 1990s as a new “safe dig” way to move earth and soil. There are many uses for vacuum excavation. The main use is for safely exposing underground utilities. Vacuum excavation is a safe, efficient alternative to hand digging. They are used alongside horizontal directional drilling (HDD) operations, municipal street and water departments and utility companies. The establishment of the Common Ground Alliance (CGA) and the National One Call System has also helped in the effort of locating underground utilities. CGA Best Practices 8.0 recognizes vacuum excavation as one of the best safe dig alternatives stating, “Vacuum excavation, when used appropriately, is an efficient, safe and effective alternative to hand digging within the designated underground facility tolerance zone.” Many laws and ordinances now mandate the use of vacuum excavation for physical locating underground utilities due to the risk of backhoes or other means damaging them. Many contractors and utility workers routinely use vacuum excavators to protect themselves, the utilities, and the customers of utility providers. Failure to protect these can be costly. There are expenses involved with down time and repair, there have been multi-million dollar claims awarded due to utility service interruption, and more than any monetary amount, lives have been lost.
Vacuum excavation is also 100 percent accurate at locating underground utilities and does so in a way that does not damage the utilities
There is no doubt the winter months add an extra challenge when trying to get utility work done, especially when you need to go below ground. Customers demand the same service in negative temperatures as they do during the warm days of summer. Colder weather is harder on equipment and the work takes longer. There is snow and ice that sometimes needs to be removed before you can get down to the soil surface. Then, depending on conditions and the region you are in, you are dealing with frozen ground and frost which at times can be harder than concrete. So, how do we accomplish the task of locating underground utilities in winter?
There are two main types of vacuum excavation; air knifing, which uses a high velocity air stream to break through the soil and hydro excavating, which uses the power of high pressure water to cut the soil loose. Both methods are effective at unearthing buried utilities; they will save you time, labor and money. Vacuum excavation is also 100 percent accurate at locating underground utilities and does so in a way that does not damage the utilities.
When dealing with clay, hard, compact or frozen soils, air knifes just don’t cut it. Since air compresses, when it hits anything somewhat hard, it will compress and simply flow around what you are trying to get through. Water, on the other hand, does not compress, so it will cut through the tough soils you are trying to get through. The addition of a hot water heater on your hydro excavator, which most manufacturers offer, allows you to cut through the frost and frozen soil with ease. The biggest advantage of using a hydro excavator with hot water is there is no need to thaw the ground, saving you time and money.
Ron Berens, of Hydro Vac Solutions, is one of the contractors who does not let a little cold weather get in the way of his work. Hydro Vac Solutions is located about 30 miles north of Winnipeg, Manitoba, Canada, in Selkirk, where they routinely work in temperatures of -20 F or lower during the winter. Berens has been in the business for over 20 years and has had plenty of experience operating hydro excavators in extreme cold. Contracting mainly for the city of Winnipeg replacing valve boxes, Berens keeps his machines busy year around. Ron operates a Ring-O-Matic 850 HiCM vacuum excavator equipped with a hot water heater in the winter months. According to Berens, “If you’re not operating with hot water, you’re wasting your time and water, you can’t get anywhere without hot water.” The valve boxes Berens is replacing are anywhere from 7 to 12 ft below the surface, most of them being around 9 ft. In the winter months, the top 5 or 6 ft of ground is frozen, yet with the heated water Berens is still able to get down to the valve boxes in about 20 minutes.
“I keep the water circulating through the whole water system until it hits about 100 F, then shut the burner off,” says Berens. “This keeps the system from freezing when he is not hydro excavating. When he is in the process of digging “I cut through the frost with the water about 170 F, this goes right through the frost, it also keeps the debris in the tank warm and prevents it from freezing.”
There are many different ways to thaw frozen ground to accomplish the work we are trying to get done. If you know where you are going to be working prior to the ground freezing, you can cover the area with frost blankets, hay, straw or some other type of ground cover that will prevent ground from freezing in the first place. This method takes a lot of pre-planning. There is the old school method of burning coal and/or wood to thaw the ground. This practice has been banned in a lot of areas due to the pollutants and chemicals given off in the burning process, which can affect both you and the environment and create a fire hazard. I have heard of glycol boiler systems being used to thaw ground, but have been told they are very inefficient and extremely noisy to operate. There is also the ground thawing trailer-mounted units that can be used, but because of their size and weight, it can be very difficult to get them where you need them. There is no doubt that using a hot water equipped hydro excavator is one of the best options on the market today.
Every job and situation presents their own problems and challenges. At the end of the day, we all share the common goal of getting the job done safely. If we can get it done more efficiently, saving time and money, that’s even better. So here’s to safe digging, oh, and stay warm too.
Jim Zylstra is sales and marketing manager for Ring-O-Matic, based in Pella, Iowa.
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