Combination trucks are reliable workhorses used for years in wastewater tank and pipe cleaning. Still, some big jobs call for more capability than jetting and vacuum can deliver.
Polston Applied Technologies has developed what it calls Combination3 (as in “cubed”) technology for such applications. Besides jetting and vacuum, the Model PAT 934 truck carries downhole pumping capability.

The truck is designed as a stand-alone cleaning system for large-diameter pipe, digesters, grit chambers, lift stations, ponds, lagoons, and other potentially hard-to-clean facilities. Built on a Western Star 4900 chassis, it delivers up to 470 hp and a 4,500 cfm Roots blower with cyclone.

A Hammelmann water pump can deliver high-pressure water. The self-retracting hydraulic hose reel can carry 500 feet of high-pressure hose; the water tank carries 1,000 gallons. An 8-inch submersible hydraulic downhole pump can move up to 2,500 gpm. The truck’s hydraulic knuckleboom crane rotates 180 degrees to enable cleaning in hard-to-reach places.

The company offers the truck as a service and not for sale. Denver Stutler, Polston CEO, talked about the technology in an interview with Treatment Plant Operator.

TPO: What market challenges were you aiming to address in developing this technology?

Stutler: We saw wet environments that were being cleaned inefficiently with equipment that wasn’t built for the task. We address problems that until now did not have truly viable solutions. For example, there are thousands of rural wastewater treatment plants that can never shut down. Our technology can perform in surcharged conditions, allowing the facilities to remain online during cleaning, and with no need for bypass pumping. That saves time and money. We also restore the capacity of those facilities and extend the life of their structures.

TPO: What is the basic advantage of this technology?

Stutler: To the traditional jetter and vacuum, we add the downhole system, which makes us like a dredge on wheels. For large treatment plants in the range of 10 to 20 mgd, it’s a three-in-one tool, like a Swiss Army knife. It provides on a single chassis the ability to clean systems while they remain in operation. Having one truck that can perform multiple functions reduces mobilization and demobilization, and limits the amount of equipment on site. It makes big jobs simpler.

TPO: How does the downhole pumping contribute to the performance of this truck?

Stutler: Vacuum technology involves only suction. You can only vacuum one atmosphere. If you are trying to vacuum water and sand, the vacuum is going to pick up the water, because it’s lighter, and it’s going to fill the tank with water before it fills with sand. Our experience shows that a slurry can be pumped faster than it can be vacuumed in most cases. In fact, when we deploy the downhole pump, we can move material up to 10 times faster than a vacuum.

TPO: Can you give a practical example of how this system works?

Stutler: Let’s consider pipe. There’s a million miles of wastewater collection pipe in the United States, and 8 to 10 percent of that is large-diameter pipe, 36 inches and above. The debris in those pipes is submerged. We can clean those pipes while the water is still in them, without bypassing the system. We put our high-pressure jets under the water and push the debris to a manhole. Then we put our downhole pump on top of the debris and pump it to the surface as a slurry. We’re not pulling it to the truck as with vacuum. We’re pushing it to the truck. Then our process separates the solids from the liquid.

TPO: What is the pumping capacity of this truck?

Stutler: The hydraulic system has the capacity to run four pumps, each rated at 2,500 gpm. Most of the time, we only run one pump, and generally we are pumping about 2,000 gpm when working with slurries (high-percent solids).

TPO: How does the sound level of this equipment compare with other technologies?

Stutler: In the downhole pumping mode, it’s extremely quiet, at under 80 dBA, so we can clean in residential neighborhoods and other sensitive surroundings. In Orlando, Florida, we worked at night cleaning thousands of feet of large-diameter pipe, without even one noise complaint.

TPO: How does this vehicle serve large facilities such as tanks, digesters and grit basins at major treatment plants?

Stutler: We have a dripless extending tube system that has up to 49 feet of reach. We found after doing considerable analysis that the reach we have accommodates a large percentage of the market we serve. However, we are looking at even longer reaches.  

TPO: What has your company done to raise awareness of this technology?

Stutler: We built our first prototype in 2012, and in 2013 we did a “seeing is believing” tour featuring demonstrations. We’ve had to roll up our sleeves and show that we can perform. In 2014, we strengthened and expanded our organization, built another truck, and began doing actual work and solving problems. Our reputation grew by word-of-mouth.

TPO: Looking ahead, where do you see your company focusing to achieve growth?

Stutler: We’re focused on applications where vacuum alone is not able to perform successfully. We don’t profess to be a panacea. We profess to solve specific problems that others traditionally have not solved. The market appears to have embraced our vision, because our trucks are busy.