Three years ago, officials in Union City, Calif., got some good news—and some bad news. The good news was that a developer was interested in building two major residential developments near the center of the city. The bad news? The storm drainage infrastructure in that area, the Line M channel, did not have the capacity to handle the additional runoff that the new construction would generate.
Ownership issues complicated the situation. The property slated for development was within Union City borders, but Alameda County was responsible for Line M, a concrete-lined open drainage channel that runs through the center of the city. With Line M at capacity, there was no way of discharging additional storm water, and that meant no development of any kind on the Union City site.
Simple but innovative
A collaboration between Union City and Alameda County resulted in a simple but innovative solution—a detention pond that worked in concert with a pre-engineered storm water lift station. The pond stores water during storm events. Afterwards, when the storm is over and the water level in the storm water channel goes down, a Romtec Utilities lift station pumps the water back into Line M.
“It was a very welcome solution to the developers, because otherwise there would not be a development,” said Carlos Jocson, city engineer. “It was actually somewhat innovative—because of the pumping station and the detention system, we were able to allow this to happen.”
The housing development is sited on a 20-acre piece of land previously used as an industrial site. Developers envisioned a cluster of 200 units of single-family dwellings on the south side of the site. To the north, another 200 units of multi-family town homes were planned.
The city began by building the 20-million-gal detention basin in the center of the development area. Then a 42-in. line was placed between the basin and the Line M storm drainage channel.
The lift station came in during the 11th Street Extension, a street-widening project that involved constructing a four-lane roadway to provide access to the housing developments.
San Jose, Calif., engineering firm Mark Thomas & Co. contacted Romtec Utilities with the parameters of the 11th Street lift station job. The Roseburg, Ore., company provides pre-engineered submersible lift stations for both wastewater and storm water. Engineers at Romtec configured the lift station, providing AutoCAD drawings, summary materials specifications and a detailed quotation for the job, which then went out to bid. The winning bidder was Santa Clara-based Anderson Pacific Engineering.
“We’ve done a lot of pump stations—built them ourselves—but this was the first pre-engineered station I’ve done,” said Matthew Mirenda, Anderson Pacific’s engineer on the project.
The pre-engineered concept is a relatively new one in the lift-station industry. Storm water lift stations are traditionally created one at a time, requiring lengthy design work, a multitude of vendors and arduous onsite construction for each station.
With the pre-engineered approach, one company takes care of the entire process, from design, quotation and submittals to construction and start-up. Complete standardized systems are configured to meet each agency’s requirements, and the entire lift station and all components arrive at the jobsite in a single shipment ready for installation. For Union City, the pre-engineered lift station’s most compelling advantage was speed.
“The project had a short fuse on it, and the pre-engineered lift station worked well for us that way,” Mirenda said. “While we were digging the hole for the wet well, someone at Romtec Utilities was building the station. When the system arrived, all we had to do was drop it in.”
The lift station includes all of the structural, mechanical, electrical and communications systems needed. Besides the preliminary engineering data, specifications and O&M manual, Romtec Utilities supplied the pre-cast wet well with self-cleaning basin and integrated pump discharge fittings; the pre-cast top slab with safe hatch and integrated well vent/cable trench; duplex pumps with liquid level sensor and pump lifting apparatus; pre-assembled valve vault with plug valves, check valves and pressure gauge; UL listed control panel and pump disconnect panel; and the standby generator and automatic transfer switch. Duplex submersible pumps for the project were supplied by ITT Flygt.
The entire system was delivered to the 11th Street site in two trucks and installed in two days, well ahead of schedule. “The work with Romtec went really great and we ended up being a month ahead of where we thought we’d be,” Mirenda said.
The detention basin and lift station have been in operation for just over a year and are performing to expectation. “The lift station has been effective,” said Richard Sealana, the city’s public works director. “It’s doing just what we wanted it to do.”
Today, when Line M fills up during a storm event, it drains into the detention basin through the 42-in. line. When it’s time to drain the pond back into the flood channel, operators come out to the site to power up the station with the Cummins standby generator. Once the generator is on, the level monitoring system controls on/off starts of the Flygt duplex pumps. Grid power will soon be connected to the site, thus eliminating a future need for the generator.
Building for the future
Union City officials consider the detention pond-lift station combination as a “mid-term” solution to the drainage issue. They plan to eventually build a highway through the area where the detention pond sits now, requiring construction of another, much larger lift station.
“The water that collects there will be put into a wet well and then pumped into a pipe system that will eventually discharge to another channel, not Line M,” Jocson said.
The detention pond and lift station proved to be an effective solution to the problem faced by the city when it came to accommodating developers.
“It kind of solved all the problems we had,” Jocson said. “Thanks to the pump station and thanks to the big hole in the ground, we were able to allow the development.”