Smaller communities typically don’t consider the purchase of sophisticated equipment because they are unable to use the equipment enough to make it pay for itself. But with some creativity, a big-ticket piece of equipment — a combination sewer jetter and vacuum unit, for example — can become useful in new and different ways.
Time to outsource?
For larger utilities, it makes clear fiscal sense to own a jetter–vacuum unit to perform routine sewer maintenance. But for smaller utilities, it’s usually cheaper to contract the work out, thus avoiding fixed labor costs and depreciation of an expensive unit.
But Mukwonago, Wis., a village of 7000, has its own sewer jetter. The unit was purchased through a subdivision development agreement with a local developer.
For Mukwonago, cleaning 20% of its sewers took less than a month. Considering the unit costs about $250,000 and has an expected reliable life of 10 years, the village basically had to pay $25,000 toward replacement/depreciation plus staff time to do the work.
A recent outside quote for doing the work set the cost at approximately $25,000 per year to do the cleaning. If this were the end of the equation, the financially prudent move would be to sell the unit and hire the contractor. But the city found some extra uses for the equipment.
Breaking down barriers
The work performed in a community often is conducted by various departments. It’s not uncommon for a community to have a public works department that handles parks, roads, and other community property. The water division typically is assigned to handle any issues found for the water treatment and distribution system. Finally, there’s the wastewater division, which focuses on sewers and the treatment plant. In Mukwonago, village leaders had the insight to combine the water and sewer divisions, which set the stage to provide cost-effective service to residents.
The obvious use of the unit was for cleaning sanitary and storm sewers. However, the jetter unit also can effectively serve as a “hydroexcavator.” The combination of a water jet to break up soil and the vacuum system to remove loosened material provides a useful tool that can dig a hole and has little chance of damaging underground utilities.
The jetter has a water storage tank, a high-pressure spray, and a vacuum to sweep up material. This combination enables the user to dig a hole in a nearly surgical manner and reduce the typical restoration cost associated with using a backhoe. Depending on soil types, the hydroexcavation can be completed as quickly as, or even faster than, conventional digging. Also, it carries minimal risk for damaging underground utilities.
The public works department found that the unit can dig a hole for a tree or signpost quickly. The hole is really just the size needed, so the job can be completed quickly and easily. On top of this, the department often takes advantage of the water storage tank to water the tree periodically to ensure growth.
The water and wastewater utility also expanded its use of the jetter beyond sewer cleaning. The jetter enabled stop boxes and valve boxes — covered vertical pipes that enable people to operate subgrade valves used to control the flow of water — to be cleaned out or surgically dug up for replacement. This might not sound like much of a savings, but the village anticipated having to pay a contractor $20,000 to repair 15 stop boxes. Instead, the staff members were able to complete the repairs in addition to their regular duties.
Hydrant painting is another unexpected use for the jetter. Traditionally, hydrant painting was ineffective because of problems with surface preparation. Today, the water tank/pressure washer easily removes any old or loose paint and rust, followed by appropriate priming and painting. For the actual painting, the village switched from brushes to sprayers, and last year, the employees painted 200 hydrants.
Another use arose when a contractor who was installing a new lift-station discharge pipe had a problem with the locating wire. The staff used the jetter to “pothole” the site to confirm the pipe location and have the contractor run locator wire.
The village also used the hydroexcavator feature to dig the hole for installing a new conduit line at the wastewater plant. Again, it was a surgical dig that made restoration simple and easy.
Revised costs and benefits
But even with these extra uses, does buying and owning such an expensive piece of equipment make financial sense? To address this issue, Mukwonago added the unit to the plant’s equipment replacement fund with a 10-year projected life. This means that the equipment must be funded each year at a rate of roughly $25,000. Each division that uses the unit pays its share toward this fund. (The village’s tight budget position led to excluding the public works department from contributing to the replacement fund for now.)
The money that goes into to the fund is the money saved by using the unit. For example, restoration costs after hydroexcavating versus using a conventional backhoe and dump truck are so low that paying toward the replacement fund is the less expensive option. This option also eliminates the need — and, therefore, the cost — to maintain and replace a dump truck and backhoe. Digging with the jetter also eliminates issues and costs associated with trenching and shoring; the work that’s done does not require entering the hole.
And, of course, owning the jetter–vacuum enables Mukwonago’s on-call staff to handle any sewer backup issue quickly and easily, which means better service to customers.
The next step for the village is to explore offering the intended and off-label uses for the jetter–vacuum unit to surrounding communities. Offering services to neighbors for a fee would further reduce the cost of the unit to Mukwonago’s citizens.
is utilities director for the Village of Mukwonago, Wis.
©2012 Water Environment Federation. All rights reserved.