Municipalities

RootX success stories

Clement Padeken, Jr.
Manager, Department of Environmental Services
City and County of Honolulu, HI

When faced with finding a solution to a problem that never stops growing, the City and County of Honolulu Department of Environmental Services took proactive measures.

The department created an aggressive preventive maintenance and root elimination program to stop the underground menace generated by the city’s lush tropical landscape. By combining old-fashioned mechanical techniques, the latest in chemical control technology, and software-generated strategic scheduling, Honolulu plans to eliminate or significantly reduce root intrusion throughout its 1,500 miles of sewer collection system over the next five years.

With some sections built as early as 1900, the Honolulu wastewater collection system is as diverse as the people, flora and fauna that share Hawaii’s island landscape. The system includes about 40 sizes of pipe, from 4-inch laterals to 84-inch force mains, in materials that include ACP, concrete, HDPE, PVC, steel and VCP. The island of Oahu experiences rain somewhere every day. This, coupled with a sandy, adobe clay or volcanic soil base, creates an ideal environment for roots to travel quickly and enter underground infrastructure of all types.

Honolulu’s response to root-related sewage spills or blockages was always prompt, but a consent decree issued several years ago pushed the Department of Environmental Services to address its sanitary sewer overflows (SSOs) caused by root intrusion on a more preventative basis. Protecting the environment and community is priority one for the agency: because of its relatively small land mass, everyone is affected.

All work for the root-control program is done by an in-house, four-man crew on call when needed. The team’s goal is to inspect and perform root elimination or control at about 2,000 feet per year. History determines most priority locations, but the staff can modify the plan based on current field findings as revealed by inspection.

“History and location are very important, but we also look at what is found upon current inspection of a line,” says Clement Padeken, Jr., a manager for the Department of Environmental Services. “If a line is infiltrated with roots, we know with certainty that surrounding laterals and adjacent lines within the culprit root’s reach will also be affected. So we extend the inspection, removal and chemical treatment to surrounding laterals and mains in the vicinity.”

Under the root-control program, each line is first inspected with a CCTV camera, and the conditions are recorded. If root intrusion is found, roots are either treated solely with RootX root-control chemical, or first physically removed by hydraulic cutting or rodding, followed by RootX application.

Crews can apply the chemical treatment in several ways depending on the size and location of the line. For 8- to 18-inch mainlines, the crew uses a Foam Dispersal Unit (FDU) 100 from RootX that works in tandem with high-pressure jetting equipment.

Besides the obvious benefits of reducing spills and meeting the consent decree requirements, the root control program has helped boost staff efficiency. Man-hours previously spent on emergencies and on monthly maintenance scheduling for repeat root-related issues have been significantly reduced. By adding chemical treatment to traditional cutting and cleaning, the city has cleared historical problem areas. These areas are now clear of intrusion for up to two years before they need to be cleaned and treated again.

“By cutting back on man-hours needed for repeat root maintenance, we can use our crews for other priority projects, and that has been one of the biggest benefits of having this program in place,” Padeken says.

Excerpts from Municipal Sewer & Water, August 2007.