Case Studies in Root Control
It’s rare to hear someone speak ill of trees. Everyone loves the shade that they give. There is a certain aesthetic appeal of a tree-lined street. A NASA study in 2015 shows just how important trees and plant-life are to keeping cities cool.
However, for trees to thrive, they must grow roots. In many cases, especially in areas with older underground infrastructure, roots pose a real problem. The intrusion of roots into sewer lines can cause structural and day-to-day issues for the systems – whether residential or municipal.
If not proactively addressed and removed, tree roots can be a huge headache. On the following pages are brief case studies in root control and removal. Our goal is to offer some perspective on how municipal and private owners have dealt with the problem of root intrusion, as well as highlight some of the available technologies to treat root intrusion.
Roots Restrict Flow
The Picote U.K. Technical Team attended to a property in Scotland in cooperation with the international services of Picote Oy Ltd., the service arm of Picote in Finland. The property owner was experiencing an intermittent back-up in their toilet line and gulley (sewer line cleanout). It was also slow to drain, running through a manhole chamber and on to a septic tank in the lower part of the back yard, causing persistent issues for the homeowner.
The main house was surrounded by a mature garden with many large trees and shrubs. As an older property, the crew immediately assumed that this would probably be a vitrified clay (VC) drain and highly likely it would be root intrusion causing the issues. Checks on the inlet to the tank found the pipe to be clear from the manhole downstream to the tank, so it was concluded that the issues were upstream of the manhole heading towards the property.
A quick look using CCTV confirmed the initial calculation and roots were found in the 4-in. VC pipe.
A Picote Super Midi and Mini Cleaner were available at the jobsite. Both the Super Midi and Mini Cleaner Millers are equipped with customized high torque motors and drivers, which are designed for heavy use and continuous heavy loads such as long-lasting and challenging descaling and root removal.
The Super Midi was the first choice for this job together with a set of 4-in. PVC Original Chains mounted on a leader with a special setting of about half the dimension of the pipe for an initial clearance pass. The PVC Chains do not have carbides and were considered a safer option for VC pipe.
Once powered up, the Miller made quick work of ripping the roots apart. Occasionally, the crew pulled the tool head back to the chamber with a mass of roots mangled in the chains. They then had to isolate the machine and clear the tool before going back in the drain and powering up again to clear further up towards the property. To clear out the remaining roots, they widened the chains out to the full dimension of the drain on a final pass. Using the CCTV unit, the Picote crew could see they were clearing the drain to the toilet of roots and restoring flow to that facility.
The CCTV inspection also showed a lateral connection in the line approximately 6 ft up from the manhole. By pouring a bucket of water into the gulley, the crew confirmed it was connected in there, but the line was extremely slow to drain, backing up in the gulley when any volume of water was poured in from the bucket.
As access into the line was restricted, the Super Midi was not a viable option and the Mini Cleaner with a 4-in. Cyclone Chain was used from the gulley pot. It took a little bit of work to get around the swan neck of the gulley with the Mini Cleaner on a low speed, but once the worker felt it push easily, they knew they were in the section of drain between the gulley and the connection on the main line. The chains made quick work of shredding the roots and with a couple of buckets of water poured into the gulley to clear the debris out, full flow was quickly restored.
At the end the project, the crew looked at preventing the roots from growing back in. They drew up a specification of work using no-dig lining techniques to put the drain back into trouble-free operation for years to come.
Provided by Picote Solutions
The City of Alameda Turns to Chemical Root Control to Maintain Sewer System
The City of Alameda, California, operates its sewer collection system under a federal consent decree, along with seven other East Bay agencies.
The main objectives of the decree are to reduce infiltration and inflow (I/I) and sanitary sewer overflows. The consent decree contains a number of work requirements to achieve those objections, including the annual rehabilitation of 2.6 miles of sewer main with associated manholes and lower laterals, pump station renovation, implementation of a private sewer lateral program, a rigorous cleaning and inspection program and root control, among other requirements.
Alameda’s Public Works Department has been working with Duke’s since 2014 to remove roots from its mainlines – a total of 110,578 ft of pipe in its Root Foaming program with pipe sizes ranging from 6 to 21 in., of which 86 percent are in the 6- to 8-in. range.
Duke’s applies Razorooter II, a herbicide-laden, thick foam with the consistency of heavy shaving cream. Duke’s crew inserts a hose from manhole to manhole. The entire system is treated as the foam compresses against pipe surfaces and penetrates cracks, joints and connecting sewers. Roots are killed on contact inside and outside the pipe walls, decay naturally and slough away, with regrowth delayed for two to three years, without harming trees or other above ground vegetation.
Online Analytic System
In 2020, Alameda incorporated Duke’s online analytic system. Using its own crew and equipment, Duke’s creates a digital map of assets (pipes and manholes) for ease of locating and providing real-time progress views of pipes assigned for root foaming treatment, in progress, completed or requiring attention by the city.
In turn, this helps Alameda store, update and retrieve accurate data instantaneously, meet compliance challenges, better collaborate with system operators/construction contractors and thus reduce time dramatically, and it integrates into their current asset management platform. The system also captures and updates attribute information during field work and record in database, including pictures and videos.
“The ability to receive real-time information, without having to send personnel to the field to verify and track work being done day-to-day is invaluable,” said Alameda director of public works Erin Smith. “It also drastically reduces planning time, we don’t have to create map books, we simply send a spreadsheet, listing which pipes to treat each year, and Duke’s takes care of the rest. And, year to year we have the history of the pipes at our fingertips.”
Alameda rotates treatment of mainlines, 50 percent one year, the remaining the second year. However, because Alameda has an aggressive replacement program, many pipes drop out of the program once they are replaced.
“Currently, our maintenance program for lower laterals is primarily driven by service calls. However, we are working toward developing a preventive maintenance program that includes cleaning, root control and condition assessment,” Smith said. “The idea is to identify the problem before the service call occurs. We are working to inspect the lower laterals a sub-basin at a time and have the information stored in our maintenance management system. This data will allow us to develop an optimized maintenance program where limited resources are focused on laterals that need it. We look very forward to working with Duke’s to leverage their GIS system for lower laterals as well as mainlines.”
Another reason Alameda is looking to collect this condition data is to possibly update its 20-year rehabilitation plan. Alameda also intends to refine its GIS data for manhole rim levels, depth and condition.
“Duke’s digital analytics platform is integral to refining our risk model. As the sea continues to rise, we will need to be crystal clear on prioritizing replacement of not only mains but also laterals and manholes,” Smith said. “Having the data digitally is great, but more importantly is the ability of the system to slice, dice and analyze giving us the information we need, in almost real-time fashion, to make the right decisions to preserve our city.”
Heidi O’Leska is CEO and owner of Vintage Juice Brand Marketing.
Removing Heavy Root Blockages in Limited Access Environments
Sometimes clearing roots is a straightforward process, other times it requires a more unique approach. Such was the case when a two-story building in southern California was experiencing a backed-up line.
Despite efforts by a previous plumbing company to snake the line, the problem was not abated. Nicholas Krewson, of San Diego Drain Krew, found that the line was being blocked by heavy root intrusions.
To be positioned effectively, the hose would need to run 120 ft down into the line from the building’s roof. Adding further complexity to the situation, the roof could not be easily accessed by ladder and the building was designed with back-to-back toilets. To mitigate an emergency dig-up, the property needed a solution to resolve the blockage and restore flow without damaging the pipe walls.
Krewson’s remedy was to break out his ½-in. Warthog Flexible SuperSpin nozzle (WS-1/2) and use it in conjunction with a water jetter to effectively clear the roots. Equipped with the Warthog nozzle and jetter hose, Krewson climbed to the roof of the two-story building to gain the access needed.
First, the line was scoped with a camera to identify the extent of the root intrusions. As the hose was lowered 120 ft through the line via a roof vent, the side-to-side flexibility of the unit’s inlet hose shortened its rigid length to navigate the limited access environment and remove the roots more effectively.
The ½-in. Warthog Flexible SuperSpin nozzle cut through the roots blocking the line to restore flow without causing damage to the pipe walls. Resolving the root blockages at this time enabled the property to complete the installation of a set of two-way cleanouts for easy future maintenance, instead of doing an emergency dig-up.
Provided by Warthog Sewer Nozzles by StoneAge
Root Clearing Saves High Profile Event
When they were tasked with cleaning and cutting roots from a pipe that was engulfed in roots, a Georgia contractor contacted USB-USA for guidance.
Digging up the pipe to replace it was not an option because of where it was situated and because the property owner had strict requirements as to what work they would allow. Another factor that played into this – and highlighted the importance of getting this pipe unblocked and cleaned – was that a major event was slated to take place at the property in just a few weeks. Based on the high-profile nature of the area, pictures of the jobsite were forbidden, only photos and video of the pipe’s condition were allowed.
After reviewing the inspection video, it was determined the pipe was 18 in. in diameter and made from concrete. This section was 40 ft long, chock-full of roots and had a few offsets. It was clear from the inspection that the pipes had not been cleaned for at least 30 years.
The first step was to get a cleaning nozzle in there to remove all the trash, debris and sand. Taking this step helped to clear the roots of any dirt and mud. Once the pipe was determined to be clean enough, it was time to deploy the Turbo chain cutter. The Turbo S600 Flexible chain cutter is a heavy-duty cutter capable of use in 12- to 24-in. pipe and the skid is adjustable within 1/16 in. inside of that range. This feature proved useful because of the offsets present inside of the pipe.
After the cutter was properly fitted, we started from the downstream manhole and cut upstream. The cutting process took less than an hour and the pipe was thoroughly cleaned.
Provided by USB-USA