By Mike Kohn, VP of Sales, Kaiser Premier
Hydro excavation is proven to be a safer, more efficient, and environmentally friendly method of excavation compared to traditional mechanical digging. Within the hydro excavation industry, there are two methods of excavation: air or water. Operators may have a preference toward one or the other, but there are many factors to consider when choosing between using air or water.
Water Use in Excavation
Historically, water has been the preferred choice for excavation projects. Using water as a means of excavation goes back to the 1800’s when pressurized water was used to clear away overburden in gold mining
applications. Water is especially effective in cutting through dense, compacted material such as clay. Projects located in colder climates, such as the northern US or Canada, ground is often frozen and too hard to dig mechanically. Heated water can be used to break up the solid ground, even in these more extreme conditions.
Hydro excavation applications can include trenching, daylighting, and digging. Traditionally, shovels or other digging machines need to be right at the excavation site. With hydro excavation, hoses can be run to the excavation site thus reducing traffic and soil disturbance near the excavation. This creates a safer work area for the operators working on an excavation.
For larger applications, such as in oil and gas, many sites have facilities on-site or nearby to process spoils generated during hydro excavation.
While water may be preferred by operators for its speed and precision, or even necessary, such as in cold weather jobs, it may not be the best choice for all excavation projects.
Environmental or Site Regulations
Many municipalities and job sites are tightening allowances on how a project impacts the environment. This doesn’t just include which excavation methods are used on a job site, but what kind of waste material is produced. As mention above, using water for excavation creates a slurry by-product that must be processed. Operators are finding that their only option to use at a site is air.
Air Use in Excavation
While air is used in a minority of excavation projects compared to water, it is an important tool for operators to have. Air is effective in applications where the soil is loose or sandy and can be easily broken up. It is the perfect option for smaller SUE, piling hole, and daylighting projects.
The material that is vacuumed into the truck’s debris body can usually be dumped back on the job site or used as backfill at the same job. This saves time and fuel costs since the operator doesn’t have to possibly deal with spoils that need to be processed off-site. Also, a contractor doesn’t have to pay for additional backfill dirt to be trucked in.
Also, air does not run out. An air compressor on the excavation truck produces all the air needed for the job, so no time is spent travelling to refill water.
As air for excavation is being mandated for more and more projects, it cannot fully replace water. Air cannot break up heavier soils or cut through frozen ground.
Each option has its benefits and drawbacks and specific applications will sometimes require air or water. But there is also a third option: air AND water.
Air and Water Combined
There are some manufacturers who are now equipping trucks with air and water excavation capabilities. This creates the best scenario for operators because they have both tools at hand. If an operator runs out of water, but is close to completing a job, it may be possible to use air to finish the project without costly delays. Or, an operator may show up at a job site expecting to use water for excavation but is then told that the site only allows using air. This isn’t a problem if the truck is outfitted with water and air excavation systems.
Trucks that are equipped with both air and water can also take advantage of tools that combine air and water into one. An air/water lance allows an operator to adjust the ratio between air and water on-the-fly. Productivity is improved because time spent switching between air or water tools is eliminated.
It’s not a clear-cut decision. Air has a place and water has a place when it comes to choosing the best option for a specific project. What is clear is that the best equipment option is a truck equipped with both air and water. Thankfully, manufacturers are realizing this and offering it as an option, but this could become the standard in the future.