New Generation of Chemical Root Control Available to Municipalities and Contractors

Nov. 22, 2002

The U.S. Environmental Protection Agency (EPA) currently is developing an audit program that will evaluate compliance of all aspects of collection system Capacity, Management, Operation and Maintenance (CMOM). So, maintaining full pipeline capacity and avoiding sewer backups and overflows are more important than ever. Effective root control, which minimizes hazards to humans, the environment and treatment plants, can be a critical element in maintenance planning for sewer lines.

Root control always has been a challenge for municipal sewer agencies. Some municipalities cut the roots out when they are found, but too often the problem is not found until a blockage and perhaps an overflow has occurred. Cutting the roots is a short-term solution and possibly can compound the problem. Roots respond to cutting the same way a hedge does; each cut produces a half-dozen new sprouts. Within three months, the roots usually are much thicker than before the cutting.

Chemicals have been used to kill roots since the mid-1970s. Until recent years, chemicals could produce negative impacts on people, treatment plants and the surrounding environment. Now there is a new generation of root control chemicals that does not produce negative impacts on the treatment plant or the people who use it yet still effectively eliminates troublesome root problems. The simplicity and effectiveness of this new generation of root control allows any applicator, whether it be a municipal sewer agency or contractor, to become a root control professional—even with minimal experience.

The new generation of chemical root control utilizes Dichiobenil, an aquatic herbicide, as its active ingredient with a label designation of "warning" as opposed to "dangerous." This new generation of chemical root control also is classified as a general use herbicide by the EPA, which means licensing may not be required for application. The formulation also contains surfactants to strip away grease and grime so the active ingredient more easily can reach the surface of the root. The rest of the formulation encourages bacterial growth to speed the natural decomposition of the dead roots.

Appling to Mainline Sewer

The new generation of chemical root control is able to foam on contact with water. This means the application process can be done directly from the package or with existing sewer cleaning equipment. The foaming action carries the active ingredient to the top of the pipe where 90 percent of root growth occurs. The foaming action also leaves a residual on the roots and pipe walls to eliminate new growth for a period of time. By pouring the dry powdered product directly into the manhole or cleanout, the product will foam by adding water or coming in contact with the existing flow. The foam will expand and move down pipe with the flow, leaving a residual on the roots and pipe walls.

The product also may be applied with existing sewer cleaning equipment by using a foam dispersal unit, which is a nozzle that fits onto the end of a jetter hose. Starting at the upstream manhole, the applicator fills the nozzle with the dry powdered product and attaches the nozzle to the jetter hose. As the jetter operator retrieves the hose, he turns the jetter on idle to add water into the nozzle that disperses the foam spray throughout the pipe, coating the roots with the root-killing formula. This also adds value to the jetter unit by being able to use the jetter as a root control machine while in the field doing other maintenance projects such as cleaning.

A regular maintenance program with chemical root control can help municipalities meet the local, state, regional and national regulations that are set up to avoid sewage overflows. CMOM is an example of those regulations. Utilizing applied chemistry such as the new generation of chemical root control will allow municipalities and contractors to meet these challenges cost-effectively, while being a valuable tool in complying with these regulations.         WWD

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