SEWER - Everything Under Control

An aggressive program against root intrusion is part of a comprehensive and effective maintenance strategy for Union Sanitary District

Union Sanitary District (USD) manages 777 miles of sanitary sewer line, most of it 8-inch clay pipes. Clay pipe means a lot of root issues. “It only takes a 0.1 millimeter gap for a root to get started,” observes Andy Morrison, collection system manager.

“At one time, roots were easily the biggest source of maintenance issues and generated the most service complaints. Thanks to a chemical root-control program that started in the early 1980s, roots are no longer the No.1 source of our stoppages. That honor now belongs to grease buildups.”

Root control is just one initiative that has helped the district achieve excellence. As the last stop for wastewater between its residents and San Francisco Bay, USD works in a highly regulated environment and runs a tight ship. The district’s TV inspection program and ongoing maintenance help keep sewage spills to a minimum.

“We need to have a management plan, a comprehensive budget, maps, contingency plans, ordinances that address sanitary sewer overflows (SSOs), the works,” says Morrison. The district’s approach is effective. In fact, USD has won the California Water Environment Association (CWEA) Collection System of the Year for large systems a record four times.

Taking it seriously

USD, founded in 1918, serves Fremont, Newark, and Union City. It is a proud organization: the facilities are spotless, the trucks and equipment are well kept, and the geographic information system (GIS) is state of the art and heavily used.

The district’s approach to root control is an excellent example of its systematic approach to maintenance, and it shows how hard work up front reduces problems and expense in the long run. The program is completely in-house. The district spends $40,000 annually on herbicide, plus $20,000 on another chemical, for corrosion control of concrete pipe and manholes.

A Vactor 2100 series combination truck, fitted with a Jet-Set Foamaker unit from Vaporooter, is dedicated to root control. Six staff members are state-certified for herbicide application, a process that requires 20 hours of training by the Pesticide Applicators Pro-fessional Association (PAPA) and renewal every two years.

“We’ve been through the entire system three times on our six-year-cycle clean and TV program,” says James Schofield, a wastewater collection supervisor (or “coach” in USD parlance). “For the root control, it is twice that — six times on a three-year cycle. Some of our schedules were overkill at first. Now we’re learning how to stretch out the cycles.”

Morrison adds, “We weren’t very successful at first. We had to learn how to cut-wait-treat.” In other words, USD learned that simply applying a root-killing agent to a clogged pipe doesn’t work. “The roots fall off and cause a blockage,” he explains.

Cutting alone isn’t the answer, either. “With just cutting, you’re actually encouraging thicker growth, like pruning, and eventually you’ll be in there every month,” Morrison says.

Now, the pipes are cleaned with a jetter and chain flail, and roots are left to grow for about six months. Then, the roots are rinsed before application. Herbicide is most effective when applied to clean, healthy roots. “If chemical is applied too soon after cutting,” says Morrison, “then bleeding sap will wash away the product. But if you wait too long, the root is too big.

“What we really want is to treat the roots right where they come into the pipe, or even just outside the entry point. And you want a clean root. Rinsing the roots removes a slime layer that can prevent chemical uptake.”

Attention to detail

As in any maintenance program, details are important. Herbicides are applied with a foamer, and USD learned that foam quality is critical. “We used to TV the lines the day after foaming to check the application,” says Morrison, “but that was a mistake. The hydro we used to pull the tag line for the camera would wash off the product, so we stopped doing that. Now we just foam it and leave it.

“The foam really needs to be like shaving cream, so it will stick and stay, and so that we can push it if we need to. Ideally, we want to be able see it if we take a look the next day. The small diameter of most of our pipes makes this possible.”

Mixing and applying foam isn’t rocket science, but it does take care to get it right. Typically, USD has bound this knowledge to the system by writing Foamer Operation: Standard Operating Procedures, a 12 page document that clearly lists all the steps required in various foamer operations, such as mixing, application, and spill cleanup. “And we have cards in the trucks that spell out nozzle retrieval rates in different situations,” says Shawn Nesgis, another wastewater collection supervisor.

The district also passes on specific knowledge by assigning new workers to experienced workers, such as Rob Shenk, a lead worker who does most of the actual foam application. “It’s pretty basic,” says Shenk, “but there is a technique, a few things about the truck you need to know.” One tip Shenk passes on to new operators is to pop a manhole lid occasionally and look at the foam to judge its quality. By taking advantage of experienced operators like Shenk, USD saves training time.

Chemicals used

The district’s choice of chemical formulations has been consistent. “We’ve used Sanafoam Vaporooter for years now,” says Morrison. “Really, there are only three choices of chemicals in California — metam-sodium, diquat dibromide, and dichlobenil. Sanafoam uses dichlobenil, a growth inhibitor, with metam-sodium, a fumigant. They’re all contact herbicides.”

The chemicals are all used in a closed system, and customers are never exposed to airborne material. It is possible to overload lines, so that foam is pushed too far up laterals, “but it’s been 18 years since we’ve done that,” says Morrison, “and then all we had to do was scoop up a little foam. We did replace a rose bush once.”

The district is keeping its options open by experimenting with diquat dibromide. Sometimes the problem isn’t the chemical but the method of application.

The consistent application of root killing chemicals discourages root growth over time, according to Schofield. “Once we’ve treated a line for a while, the roots will find another water source,” he says. “It’s like using Roundup in a yard. If you’re consistent, you’ll get results.”

Consistent application means the district can stretch the time between root treatments, from every three to six months when the program started, to three years between treatments now. A scheduling glitch once kept part of the system off the root control program for more than three years, and there was substantial root buildup when the problem was discovered.

Since the root-control chemicals used are monitored by the state, USD keeps careful records. “We have records of gallons used, in how many applications,” Nesgis says. “We track the chemical registration numbers, and we share it all with the county agricultural commissioner. Keeping good records is the best way to avoid headaches when it’s time for an inspection.”

It all works together

Of course, the root control program isn’t separate from the rest of USD operations. It’s an integral part that depends on other things working well. For instance, the district’s GIS, based on ArcIMS from ESRI and GeoSmart from MoosePoint Inc., is the best way to schedule cut-wait-treat, and the best way to systematically cover all parts of the system at the desired intervals. Cleaning Area Reports tell workers how they’re doing compared to a yearly schedule and help managers to allocate resources.

CCTV is also a vital underpinning of the entire program. The district runs two vans equipped with Omni III cameras and 6-inch to 15-inch crawlers from RS Technical Services Inc. “We really focus on TV programs,” says Schofield. “We find problems before they find us.”

Besides capturing the entire system every six years, USD applies TV as needed in problem areas. When that happens, “We get everything from manhole to manhole, and get more than we need,” Schofield says.

New pipe is inspected a little less than a year after installation, so that USD can take advantage of contractor warranties, if needed. In recent years, the district has moved from VHS to digital capture, replacing a large video library with a 12 terabyte disc drive. Digital capture also enables video links that are accessible from the GIS.

USD constantly seeks new ideas and techniques. One way of doing this has proven popular with surrounding districts: “We host equipment shows,” says Morrison. “We bring in vendors and other agencies. We have a grill going. Last time we had 300 people.” Besides giving vendors a chance to showcase new equipment, the shows give wastewater professionals a chance to talk informally and trade tips.

Romance of maintenance

Stewart Brand, creator of the Whole Earth Catalog and life long thinker about sustainability and the role of civilization, has written:

“The romance of maintenance is that it has none. Its joys are quiet ones. There is a certain high calling in the steady tending to a ship, to a garden, to a building. One is participating physically in a deep, long life.”

Tending a wastewater system confers no glory, yet it is a high calling. By keeping the lines flowing, USD serves its customers efficiently and protects the environment. Its quiet, behind-the-scenes competence is an example for those involved in maintenance of all kinds.



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