The Stone Canyon Water Quality Improvement Project has two goals: meeting tough federal surface-water regulations, and providing safe and reliable water to 400,000 Los Angeles residents.
The Los Angeles Department of Water and Power budgeted $75 million for the project. Officials at the agency spent a decade working with surrounding neighbors. Construction ran from 2004 through the end of 2007.
It was, in short, a huge project. But, when the department officially wraps up its Stone Canyon Water Quality Improvement Project this spring, it will have accomplished two equally huge goals: The new water-treatment facilities will allow Stone Canyon to meet tough federal surface-water regulations. The project will also provide a safer and more reliable source of water to more than 400,000 Los Angeles, CA, residents.
It should be of little surprise that the Stone Canyon Water Quality Improvement project was such a large one. It is itself part of an even larger effort on the part of the Los Angeles Department of Water and Power to spend up to $132 million over five years to upgrade the security and safety of the city’s water system. The terrorist attacks of 9/11, spurred the city to tackle such a large endeavor.
“This is a project that we’ll all look back on as an important one,” says Kurt Wells, project manager with the Los Angeles Department of Water and Power. “It’s been one that the department has been working on for more than a decade, so it’s a nice feeling to see us get to the point where it is almost complete.”
The project is also one that can serve as an example to other municipalities facing massive water-treatment projects, that have several different goals attached to them. The Stone Canyon project was a challenge, certainly. But officials with Los Angeles’ water department met those challenges through careful and patient planning.
A Big Job
The main goal of the improvement project was to remove one of the two large reservoirs at Stone Canyon from service by January 1, 2005, the deadline for the Los Angeles Department of Water and Power to meet tougher state and federal water-quality regulations for open reservoirs in California.
The regulations, part of the Surface Water Treatment Rule of the Federal Safe Drinking Water Act, required the Los Angeles water department to take four of its open reservoirs across the city out of service, because the department had determined that they had the potential to be significantly contaminated by surface water runoff. One of the reservoirs that the department’s officials targeted was the lower reservoir at Stone Canyon, located in the Santa Monica mountains, about 13 miles northwest of downtown Los Angeles. Stone Canyon, which features both an upper and lower reservoir, serves residents of the Pacific Palisades, Santa Monica Mountains, and West Los Angeles areas.
Now that the improvement project is mostly done, the lower Stone Canyon reservoir has indeed been taken out of circulation. It now serves primarily as a storage reservoir for emergency use. A new 63-inches-in-diameter bypass pipeline that stretches some 8,000 feet–—about half of this length submerged deep under the lower reservoir’s surface–—allows the department to bypass the lower reservoir and send treated water directly to its customers.
The department’s contractors finished the majority of construction on the improvement project by the end of 2007. Wells says that the new water-treatment facilities at Stone Canyon reservoir will be fully operational in May 2008.
For officials with the department, the day when they turn operations over to the site’s personnel will come as a relief. It will mean that their more-than-decade-long Stone Canyon project is officially over.
“Basically, we built a whole water-treatment site at Stone Canyon,” Wells says. “We built some facilities here that we had never built anywhere before. We had to use some different techniques here that we had never used anywhere else, like when we submerged more than 4,000 feet of pipeline in the lower reservoir. It was an interesting and massive project, and I think it went extremely well.”
The new Stone Canyon water-treatment complex now includes reconstructed pumping and water-treatment facilities, a small filtration plant that can handle 6.5 million gallons of water a day, and the new 60-inch pipeline that allows treated water to bypass the Lower Stone Canyon Reservoir. Construction crews also built the first chlorination station in the department’s history while completing the project.
Department officials could clearly see the finish line as the project moved into the later parts of 2007. It was by then that crews had completed the majority of major construction. By the end of the year, in fact, the department was mostly concentrating on installing new landscaping around the site.
Then, in early 2008, officials with the Los Angeles water department were scheduled to begin the commissioning process of the new Stone Canyon facility. The plan was to have the department oversee the operations at the plant for two to three months. In April or May, the department then expected to turn operations over to Stone Canyon’s operating personnel for full-time service.
A Two-Pronged Reason to Build
The primary impetus for the Stone Canyon improvement project came way back in 1991, when officials with the Los Angeles water department determined that the lower Stone Canyon reservoir would violate the new stricter regulations contained in the Surface Water Treatment Rule.
The reservoir had been an important part of the department’s water-treatment system. It is large enough to hold 3.38 billion gallons of water, ranking as one of the biggest of the city’s distribution reservoirs. The facility’s upper reservoir, in contrast, only holds 138 million gallons of water. That upper reservoir, though, was built with protections against runoff, including perimeter channels, that the lower reservoir did not contain.
Because of the improvement project, water from the lower Stone Canyon reservoir no longer feeds directly into the pipelines that service the water department’s customers. Instead, costumers receive water from the Los Angeles Aqueduct Filtration Plant in Sylmar, thanks to the new bypass pipeline.
A second reason for the project came soon after the terrorist attacks on New York City and the Pentagon in 2001. The water department took on a five-year project to upgrade security at the city’s water system. As part of this huge effort, the department installed new security cameras and intrusion alarms at the Stone Canyon reservoir complex.
“We had to take action once the state changed the water-quality regulations for water-treatment plants,” Wells says. “We knew that our best option was to take the lower reservoir out of service. We had runoff from the canyon that if it got into the lower reservoir it went directly into our upper reservoir, too. It was more cost effective to take treated water directly from the Los Angeles Reservoir in Sylmar and provide that to our customers instead.”
The lower reservoir at Stone Canyon is now out of service. But, that doesn’t mean it doesn’t have any purpose. Department officials are now using it as an emergency water-storage facility. For instance, if the city suffers through a particularly fierce 100-year storm, department officials can overfill Stone Canyon’s upper reservoir, and use the lower reservoir to handle this overflow. The department could then treat the overfill from the lower reservoir with Stone Canyon’s new membrane filtration plant before distributing it to its customers.
“We wouldn’t be putting any new water in that lower reservoir, but if we do have storm water that results in an excess of water, we could treat it and distribute it,” Wells adds. “If there was some other kind of emergency situation, say we lost water coming into the site, we could reconnect to that reservoir and issue a boil-water notice. At least that way, we’d be able to keep water coming into the pipes.”
An Important Pipeline
A key component of the Stone Canyon project is the 8,000-foot-long bypass pipeline that funnels water past the lower reservoir. Installing that pipeline was also one of the project’s biggest challenges.
That’s because engineers decided that about 4,200 feet of the pipeline should be submerged at the bottom of Stone Canyon’s lower reservoir. By submerging that much of the pipeline, project engineers not only saved the department significant money–—about $10 million–—but provided a respite to the water-treatment facility’s neighbors. For every foot of pipeline submerged, the department’s construction crews saved a foot of costly, and messy, tunneling work.
“Submerging the pipe saved a significant amount of money,” says Richard Bentwood, principal project manager with Parsons ES in Pasadena, CA, the company that designed the high-density polyethylene pipeline used in the project. “It was much less costly to put that pipe in the bottom of the reservoir than it would have been to tunnel the full length. We were offsetting close to 4,200 feet of tunneling. That 4,200 feet would have been very costly.”
By submerging the pipe, the water department also maintained good relations with the homeowners of Los Angeles’ Bel Air neighborhood. “There just wasn’t any routing that would have been acceptable to the homeowners,” Bentwood says. “No matter what alignment they would have chosen, it would have been very invasive. It would have created a number of environmental issues.”
Maintaining good relations with Bel Air residents was crucial. Water department officials had worked with nearby residents for 10 years to develop plans for a water-treatment site that was as unobtrusive as possible.
This process entailed several compromises, on both the part of residents and the water department. For instance, based on the concerns of homeowners, the department did scale down the size of Stone Canyon’s new membrane filtration plant. Department officials were able to do this by taking the lower reservoir offline and sending treated water through the bypass pipeline and two bypass tunnels. With the lower reservoir not in service, Stone Canyon did not need as large of a filtration plant.
The footprint for the pumping and membrane filtration building is small, about 150 feet by 150 feet. This concession is just one example of the delicate relationship building that took place during the project. Department officials met frequently during the planning and construction phases of the project with members of the Bel Air Association, Glenridge Homeowners Association, Residents of Beverly Glen and the Roscomare Valley Association.
Raul Banuelos, the Los Angeles Department of Water and Power’s manager of major projects in the water system, said that the Stone Canyon project marked the first time that the department has ever installed an HDPE submerged pipeline in any of its reservoirs.
“We debated internally here, whether the savings were going to be significant enough to warrant submerging the pipeline,” says Banuelos. “We do want a pipe that will last 100 years or more, too. Was this going to do that?”
After much analysis, department officials determined that they would save about $10 million, by submerging the HDPE pipeline rather than creating tunnels for it.
Those savings were significant enough to inspire department officials to go with the submerged pipe.
“Tunneling 4,200 feet in southern California, in anywhere, really, is a pretty expensive enterprise,” he says. “Then, there are the potential issues with tunneling. You never know when you start tunneling what you are going to find. By us minimizing the amount of tunneling, and installing pipeline in the bottom of the reservoir, we significantly diminished the risks of this project.”
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Photo: Underwater Resources |
| A new bypass pipeline, 63 inches in diameter and stretching 8,000 feet (about half of its length being submerged under the lower reservoir's surface), allows the department to bypass the lower reservoir, sending treated water directly to its customers. |
The bypass line, known as Bypass Line Number 2, contains five major parts: a 2,400-foot north tunnel, 10 feet in diameter with an internal steel pipe; the 4,200-foot-long HDPE pipeline; a 640-foot-long south tunnel, 10 feet in diameter and also with an internal steel pipe; a 860-foot-long steel pipeline, 60 inches in diameter, that connects the new bypass system to the existing Bypass Line Number 1 and also connects the submerged pipeline to the two tunnels; and nine valve and meter vaults, ranging in depth from 14 to 65 feet.
Contractors delivered the HDPE pipeline to the site in 40-foot segments. Using a fusing machine made by McElroy Manufacturing of Tulsa, workers fused the segments while they sat on land. It took about two hours to fuse each joint.
After the joints were fused, a floating crane pulled the pipeline over rollers and onto the surface of the lower reservoir. Eventually, the crane had pulled the complete 4,200-foot HDPE pipeline along the surface of the water.
The next challenge was to submerge the pipe. Contractors then used the floating crane to lift sections of the pipeline out of the water and attach square concrete anchor ballasts along it every 10 feet. Crews attached a blind flange with a water-connection tap at each end of the pipeline.
To submerge the pipe, workers slowly filled it with water. All the while, the crane supported the HDPE pipeline’s middle section. This allowed the workers to fill the pipe’s northern end with water first, so that the pipe would gradually submerge and move into its correct position on the
reservoir floor.
The process worked, but, it was not perfect, something not surprising considering the size and scope of the project. Terry Flinn, project manager with Underwater Resources Incorporated, in San Francisco, was intimately involved in the project. Underwater Resources actually built the 8,000-foot-plus pipeline used in the project.
Flinn had recommended that the ballast blocks attached to the HDPE pipeline be bottom-weighted to prevent rotation of the pipe before it was submerged. Other engineers disagreed, so the project continued without the weighted ballasts.
This meant that workers did struggle somewhat to keep the pipeline from rotating. But crewmembers did work around the problems and successfully completed the project, Flinn says.
“As you can understand, once you get into a remote location with rental equipment, it’s very difficult to stop work and wait for a resolution from a large general contractor who is waiting for direction from a large bureaucracy,” says Flinn. “We had to keep on moving ahead. We did the best we could, and I think it all went well.”
He says he and his company gained valuable experience from the Stone Canyon project. “It’s an interesting day once you decide it is submergence time,” he adds. “That is the critical time, when you’re pumping water in one end and letting air out the other through valves. That’s when the pipe is at its most vulnerable condition for kinking. That is the critical time in the whole operation. You have to get through that part as quickly as possible.”
Bentwood agrees with Wells that submerging the pipeline was the right way to go. To tunnel that distance would have not only cost more, it would have been more intrusive to neighbors. Considering that the Los Angeles Department of Water and Power had dedicated more than a decade to working with the surrounding communities on the project, it would have been a terrible waste to end up aggravating them with extensive digging and tunneling near their properties.
“The tunneling that we did have to do from a homeowner’s perspective was barely visible,” says Bentwood. “It was done mostly during the daylight hours, so there was very little lighting annoyance in the nighttime hours. There was no blasting. And then the lake-bottom pipeline we installed was probably very interesting to the neighbors who were able to watch it floating out there across the full length of the reservoir. It was a fascinating project. It was all very efficient, very well done.”