Chemical root control, a fats, oils and grease (FOG) program and a comprehensive preventative maintenance schedule program that involves inspection, cleaning and rehabilitation is keeping the City’s 400 miles of sanitary sewer lines and 8,500 manholes in top condition. The City’s efforts to address its infrastructure needs began just six years ago. How is that possible you ask, considering Palmdale is more than 50 years old?
Incorporated in 1962, the City of Palmdale — which refers to itself as the aerospace capital of the United States — has experienced significant and rapid growth spurts over the last 30 years, growing from 23,000 in 1986 to present day 155,000 in population. Primarily a residential area, the City covers a fairly large footprint of 104 sq miles of mostly flat lands, with the San Gabriel Mountains separating it from the rest of Los Angeles County, which played the central role in the upkeep of its wastewater infrastructure until a few years ago.
When Palmdale was originally incorporated, it entered into a general service agreement with the County of Los Angeles to maintain its infrastructure. In 2006, the State Water Resources Control Board (SWRCB) issued an order for all publicly owned treatment works and sewer systems to be held responsible for monitoring their systems due to the high volume of sanitary sewer overflows (SSOs) throughout the state.
“We still owned the system, but we were not responsible for or incorporated into the maintenance and management of it,” explains Tim Carney, collection systems supervisor for the Utilities Division of the City’s Public Works Department. “City Council and our public works director decided that if we were going to be held responsible for the system and any problems or failures, we want to be responsible for its maintenance and management.”
After that, Palmdale officials took the steps to take over control of its underground infrastructure maintenance from Los Angeles County Public Works. The City officially took over on July 1, 2009. Carney was the lone employee of the Utilities Division’s Sewer Maintenance Department. Initially, the City hired the county to do some maintenance work and also put out two contracts for sewer maintenance and inspection.
Today, all of those things are handled in-house through the Utilities Division’s 12 employees. As luck would have it, when the City began handling its wastewater management, other city departments were tightening their belts due to the economic downturn, enabling the Utilities Division to bring those workers on its payroll. “It was the perfect storm for us,” Carney says. “We were able to hire people with experience and knowledge to help form our department.”
Palmdale remains just a collection system for its 38,000 residential and 2,500 commercial connections; the sanitation district of L.A. County manages and operates the two wastewater treatment facilities the City’s lines drain to. The City’s system includes mostly vitrified clay pipe (VCP) with some ductile iron and PVC pipe filling out the remainder of the system. Eighty-five percent of the system has been built since the 1980s, making it relatively new. Older sections of the City sewer were constructed in the 1950s.
When the City took over the infrastructure’s maintenance, officials didn’t have much to go on to assess its immediate needs. “When we looked at the initial data we got from L.A. County, we saw that they were doing periodic cleanings where there were some problems. [The data showed] there were root issues in the majority of the older neighborhoods or FOG problems coming out of the commercial and residential areas,” Carney says. “Now that data only represented about 15 percent of the system but we thought, ‘Oh no — everything is bad!’ That prompted us to clean and hit everything once. We created maintenance forms for the contractors and the county to document the data. We purchased a data maintenance software package and started feeding it data.”
Carney says it took about five years to clean, inspect and assess every line and manhole and things weren’t as dire as first perceived. Pleasantly surprised is more like it. “For the most part, we found that we are in relatively good shape,” Carney says. “We did have areas where there are root and FOG issues, but we were really lucky.
“Our biggest concern [when we took over the maintenance] was that we didn’t know what was out there,” he says. “It was the great unknown. We hadn’t seen anything or have a lot of data from the county to go on. Our first goal was to get out there and do sewer maintenance cleaning and inspection of our entire system as fast we could so we would have that data, so we know what’s out there and take the necessary steps to correct the problems when we have them.”
The Utilities Division analyzed the contract video from the first four years and did excavation repairs on about 1,000 lf of pipe and used cast-in-place liners on another 2,000 lf, as well as raising 215 manholes to grade. Carney and his crews determined that 15 to 20 percent of the system had some sort of operation and maintenance need that involved roots.
Roots and FOG
With the amount of VCP in the system, it should be no surprise that root infiltration was a focal point of the City’s preventative maintenance efforts. Carney notes that the root fingers and balls found in the pipes were the cause of several overflow issues, restricting some 90 percent of flow in those pipes. The City invested in root cutting platforms and nozzles to start removing the root obstructions. But root cutting doesn’t solve the problem because the roots eventually grow back.
Carney says that a chemical root control demo with Douglas Products and West Coast Safety Supply stuck with him and the City began to weigh the options of chemical root control vs. root cutting, with chemically treating the roots winning out. The City purchased a Jet Set Commander Foamer from Douglas Products to be used on its hydro jetter vehicle. Crews received training from Douglas Products and West Coast Safety Supply.
“We’ve committed ourselves to chemically treating 90,000 lf a year,” Carney says. “It sounds like a lot, but it really isn’t.
The City has also addressed its FOG issues, which were mainly found in its residential areas. Officials have worked and communicated with the public on how to properly handle fats, oils and grease disposal. An Environmental Compliance program was implemented in 2011 to permit, monitor and inspect commercial facilities discharging to the City’s sewer system, as well.
Because the City only started doing regular chemical root control in earnest in December 2014, it’s too early to see how it has impacted the system from a financial view. However, Carney likes what he sees from the inspection video and data so far. “We’ve gone back and videoed areas where we started foaming a year to 18 months ago and we see a significant reduction,” he says. “Before we had multiple serious grades of root intrusion and defects and now we’re seeing where the roots died off. It’s a small sampling, but we are really pleased with how it’s working. It gives us impetus to get the rest of these areas foamed and processed.”
The City’s preventative maintenance plan includes its intent to clean and inspect every segment of pipe and manhole every five years. Crews have the authority to adjust the schedule, based on the visuals they are seeing in the field. Today, crews use an Envirosight Rovver X camera system as a stopgap inspection measure; plans are in the works to purchase a CCTV inspection vehicle, allowing crews to set up a permanent inspection schedule. Currently, the City has a GapVax combination vehicle and Sewer Equipment Company of America (SECA) HydroJetter, which will handle the City’s periodic maintenance and five-year maintenance, respectively. The City is also finalizing its purchase of a POSM inspection software package for its CCTV data capture and analysis.
“Starting from scratch is a little scary but it’s gone fairly well,” Carney says. “Over time, we have a system down that we are comfortable with. We are not scrambling or reactive [anymore]. We’re getting to the point where we are proactive and stopping problems before we have an overflow. That is the goal.”