DSRSD Upgrades Water Infrastructure
Keeping one step ahead is something DSRSD is constantly striving for with its long-range master plans and 10- and 2-year capital improvement budgets. Ensuring the District can provide potable water to customers not only now, but also in the years ahead, remains a cornerstone. Engineering staff have been overseeing multiple projects to ensure the water distribution system will provide water for years to come.
The District hired consultant Wood Rodgers Inc. in December 2020 to design the new reservoir. As part of the design process, Wood Rodgers will assess the best location by considering elevation, hydraulic modeling, and land acquisition. Wood Rodgers will also determine whether the reservoir will be above ground, below ground, or partially above and below ground.
“Water demands have varied, and we do not want to over- or under-size this new reservoir,” says DSRSD Associate Engineer Sukhpreet Mann. “The District is planning to meet future 2035 buildout water demand conditions with Reservoir 20B.”
Design will be based on an updated hydraulic model for the water distribution system and is projected to be completed in May 2022. Construction may be completed at the end of 2022 on this $7.7 million project. Depending on the chosen location, the reservoir could be located near a protected golden eagle habitat, in which case DSRSD would halt construction during breeding and fledging months (typically from January through July each year), delaying completion of the project.
“We’re not taking advantage of the full amount of flow coming out of the turnout because we’re limited in pumping capacity,” says Assistant Engineer Jose Oropeza. “That’s one of the things this rehab will address.”
Engineering firm West Yost has been working with the District to update the hydraulic model, which will be use during the design process. The model looks at anything that affects the distribution system and how it responds, and it is compared to actual data to evaluate the model’s accuracy. Engineers look at trends, such as the filling and emptying of reservoir tanks, and analyze the data to identify current deficiencies and what effects those have on the distribution system.
“West Yost will essentially model different scenarios and prepare a preliminary design report that outlines options. We then discuss the pros and cons including costs, feasibility, and various challenges before selecting a design,” Oropeza says.
The design will address improving pumping capacity as well as low pressure. Options are expected to include adding an additional pump as part of either retrofitting or entirely replacing the station at the same site or another site.
Construction is expected to begin closer to the end of 2022 or early in 2023.
“Building Turnout 6 is ultimately for redundancy,” says Associate Engineer Jason Ching. “If you look at the existing turnouts, we have enough capacity to get the District through the projected 2035 buildout. However, when we take a turnout offline for maintenance, this new Turnout 6 will allow us to meet our water demands.”
The Board of Directors approved a consulting agreement with HDR Engineering in August 2020 to design Turnout 6. The consultant is taking a closer look at location and alignment options that consider redundancy, reliability, operability, maintainability, capital costs, environmental impacts, permitting, and property procurement. This turnout would connect to the Cross Valley Pipeline, one of two Zone 7 transmission mains that run through DSRSD’s service area. The connection would run north underneath I-580 from Pleasanton to Dublin. Currently, 70% of DSRSD’s water supply (three turnouts) come from Zone 7’s older Santa Rita Pipeline. This pipeline is more likely to need repairs, as age is typically a good indicator of future leaks, potential rehabilitation, or interruptions to service.
Turnout 6 would require fluoridation facilities and building space for a possible future pump station. A leading location for consideration is a vacant lot just east of the Kaiser Permanente building near the southeast corner of Dublin Boulevard and Lockhart Street where the District could potentially obtain property rights for a quarter or a third of an acre.
“The land is wide open right now, which is great for us,” Ching says. “We don’t know for sure if the District will need a future pump station, but it is likely as water demands increase.”
The lot is owned by Kaiser, and DSRSD has been in contact with them about surveying the area and conducting geotechnical investigations that would look at groundwater levels as well as the hardness of the underlying earth. These factors will come into play when the project goes to construction, which will involve trenchless methods of drilling under the freeway. Ching says he anticipates using a 24-inch diameter carrier pipe for the potable water, which would be within a larger, 28-inch casing pipeline. The casing pipeline acts as a sleeve for the carrier pipe. If the carrier pipe were to leak, water would fill the casing pipe and be conveyed to one or both sides of I-580 in order to protect the freeway.
The goal is to have capacity for 6,000 gallons per minute, or 8.64 million gallons a day. Engineering staff expect to complete surveying and investigating the geotechnical characteristics of the site by the end of 2021, and that the project designs to select from will be ready by summer 2022. Before construction can begin, designs will be reviewed by Zone 7, Kaiser, Caltrans, and the City of Dublin.
“There are a lot of entities that we need to coordinate with, and the project schedule is highly dependent on getting approval from some of these outside agencies,” Ching says.
Isolation valves are critical components of the water distribution system that allow District operators to turn segments of pipes on and off. Repairing or replacing isolation valves is an important part of maintaining a water distribution system and essential to operating the system efficiently. When replacing valves, the District looks for opportunities to add valves at tee and cross intersections. Additional valves improves water main shutdown reliability and reduces the number of customers affected by any water main shutdowns in the future.
Blow-off valves, located at the end of cul-de-sacs or other water system dead-ends, are also being replaced with larger diameter valves to improve water main flushing. Water main flushing is when operators force water through the pipes at up to 2,000 gallons per minute, which removes sediment and cleans the pipes. This is done to improve water quality. Increasing the diameter of blow-off valves from 2 inches to 4 inches allows operators to increase water main flushing velocities and this improves their cleaning efforts.
In addition, water distribution pipelines are often in soils with high salinity. The high salt content is corrosive to iron valves and other pipeline materials, so this project is introducing cathodic protection to the valves that includes special corrosive-resistant coatings, high-quality stainless steel materials, and sacrificial anodes. The sacrificial anodes protect District valves from corrosion because they are made from materials that have more active voltage than the iron, steel, and brass pipeline materials. Cathodic protection will extend the life of newly installed valves.
“We’re doing everything we can to make sure those valves do not corrode for a long time,” Associate Engineer Sean O’Reilly says. “It’s all about reliability and protecting customers’ water supply and water quality.”
The District contracted with West Valley Construction Company and McGuire and Hester to replace the valves. In order to replace valves, operators have to shut off the water temporarily. DSRSD staff hang notices on front doors 24 to 48 hours in advance of water shutoffs for impacted customers.
A New $7.7M Reservoir to Store More Drinking Water
DSRSD engineers look at long-range buildout for the service area, currently anticipated to occur in 2035. They use recommendations from the Water System Master Plan updated in 2016. Based on future development growth in the service area up to 2035, the District will need a new 1.3 million gallon reservoir to provide drinking water storage capacity for eastern Dublin and the Dougherty Valley.The District hired consultant Wood Rodgers Inc. in December 2020 to design the new reservoir. As part of the design process, Wood Rodgers will assess the best location by considering elevation, hydraulic modeling, and land acquisition. Wood Rodgers will also determine whether the reservoir will be above ground, below ground, or partially above and below ground.
“Water demands have varied, and we do not want to over- or under-size this new reservoir,” says DSRSD Associate Engineer Sukhpreet Mann. “The District is planning to meet future 2035 buildout water demand conditions with Reservoir 20B.”
Design will be based on an updated hydraulic model for the water distribution system and is projected to be completed in May 2022. Construction may be completed at the end of 2022 on this $7.7 million project. Depending on the chosen location, the reservoir could be located near a protected golden eagle habitat, in which case DSRSD would halt construction during breeding and fledging months (typically from January through July each year), delaying completion of the project.
$6.7M Rehab of pump station to Increase Efficiency
Another way the District plans to meet future water supply demands will be to rehabilitate Pump Station 1A. Located near the intersection of Amador Valley Boulevard and Stagecoach Road, this station pumps water from wholesaler Zone 7 Water Agency to DSRSD’s distribution system on the west side of the service area. The existing pump station is undersized: Zone 7 is able to provide 5,000 gallons per minute (GPM) at the turnout, but due to the number and type of pumps at this station, the District can only pump a maximum of 3,600 GPM.“We’re not taking advantage of the full amount of flow coming out of the turnout because we’re limited in pumping capacity,” says Assistant Engineer Jose Oropeza. “That’s one of the things this rehab will address.”
Engineering firm West Yost has been working with the District to update the hydraulic model, which will be use during the design process. The model looks at anything that affects the distribution system and how it responds, and it is compared to actual data to evaluate the model’s accuracy. Engineers look at trends, such as the filling and emptying of reservoir tanks, and analyze the data to identify current deficiencies and what effects those have on the distribution system.
“West Yost will essentially model different scenarios and prepare a preliminary design report that outlines options. We then discuss the pros and cons including costs, feasibility, and various challenges before selecting a design,” Oropeza says.
The design will address improving pumping capacity as well as low pressure. Options are expected to include adding an additional pump as part of either retrofitting or entirely replacing the station at the same site or another site.
Construction is expected to begin closer to the end of 2022 or early in 2023.
A New $9.5M Turnout for System Redundancy
DSRSD engineers are planning a new turnout. Turnouts are essentially large meters that measure the amount of water the District receives from Zone 7 Water Agency, our wholesaler. This new turnout will provide redundancy and reliability for the water distribution system. The District currently has four active turnouts (Turnouts 1, 2, 4, and 5). Turnout 3 is disconnected from the system and has no fluoridation facilities. Occasionally turnouts must be temporarily shut down for maintenance. This new turnout will provide a reliable way for DSRSD to deliver water during those times.“Building Turnout 6 is ultimately for redundancy,” says Associate Engineer Jason Ching. “If you look at the existing turnouts, we have enough capacity to get the District through the projected 2035 buildout. However, when we take a turnout offline for maintenance, this new Turnout 6 will allow us to meet our water demands.”
The Board of Directors approved a consulting agreement with HDR Engineering in August 2020 to design Turnout 6. The consultant is taking a closer look at location and alignment options that consider redundancy, reliability, operability, maintainability, capital costs, environmental impacts, permitting, and property procurement. This turnout would connect to the Cross Valley Pipeline, one of two Zone 7 transmission mains that run through DSRSD’s service area. The connection would run north underneath I-580 from Pleasanton to Dublin. Currently, 70% of DSRSD’s water supply (three turnouts) come from Zone 7’s older Santa Rita Pipeline. This pipeline is more likely to need repairs, as age is typically a good indicator of future leaks, potential rehabilitation, or interruptions to service.
Turnout 6 would require fluoridation facilities and building space for a possible future pump station. A leading location for consideration is a vacant lot just east of the Kaiser Permanente building near the southeast corner of Dublin Boulevard and Lockhart Street where the District could potentially obtain property rights for a quarter or a third of an acre.
“The land is wide open right now, which is great for us,” Ching says. “We don’t know for sure if the District will need a future pump station, but it is likely as water demands increase.”
The lot is owned by Kaiser, and DSRSD has been in contact with them about surveying the area and conducting geotechnical investigations that would look at groundwater levels as well as the hardness of the underlying earth. These factors will come into play when the project goes to construction, which will involve trenchless methods of drilling under the freeway. Ching says he anticipates using a 24-inch diameter carrier pipe for the potable water, which would be within a larger, 28-inch casing pipeline. The casing pipeline acts as a sleeve for the carrier pipe. If the carrier pipe were to leak, water would fill the casing pipe and be conveyed to one or both sides of I-580 in order to protect the freeway.
The goal is to have capacity for 6,000 gallons per minute, or 8.64 million gallons a day. Engineering staff expect to complete surveying and investigating the geotechnical characteristics of the site by the end of 2021, and that the project designs to select from will be ready by summer 2022. Before construction can begin, designs will be reviewed by Zone 7, Kaiser, Caltrans, and the City of Dublin.
“There are a lot of entities that we need to coordinate with, and the project schedule is highly dependent on getting approval from some of these outside agencies,” Ching says.
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| Contractors from West Valley Construction install a new water main tee and isolation valves to replace an older tee. |
$3.25M to Replace Aging Valves throughout system
From July 2019 through June 2022, DSRSD is repairing and replacing isolation valves, blow-off valves, and fire hydrant valves throughout the water distribution systemIsolation valves are critical components of the water distribution system that allow District operators to turn segments of pipes on and off. Repairing or replacing isolation valves is an important part of maintaining a water distribution system and essential to operating the system efficiently. When replacing valves, the District looks for opportunities to add valves at tee and cross intersections. Additional valves improves water main shutdown reliability and reduces the number of customers affected by any water main shutdowns in the future.
Blow-off valves, located at the end of cul-de-sacs or other water system dead-ends, are also being replaced with larger diameter valves to improve water main flushing. Water main flushing is when operators force water through the pipes at up to 2,000 gallons per minute, which removes sediment and cleans the pipes. This is done to improve water quality. Increasing the diameter of blow-off valves from 2 inches to 4 inches allows operators to increase water main flushing velocities and this improves their cleaning efforts.
In addition, water distribution pipelines are often in soils with high salinity. The high salt content is corrosive to iron valves and other pipeline materials, so this project is introducing cathodic protection to the valves that includes special corrosive-resistant coatings, high-quality stainless steel materials, and sacrificial anodes. The sacrificial anodes protect District valves from corrosion because they are made from materials that have more active voltage than the iron, steel, and brass pipeline materials. Cathodic protection will extend the life of newly installed valves.
“We’re doing everything we can to make sure those valves do not corrode for a long time,” Associate Engineer Sean O’Reilly says. “It’s all about reliability and protecting customers’ water supply and water quality.”
The District contracted with West Valley Construction Company and McGuire and Hester to replace the valves. In order to replace valves, operators have to shut off the water temporarily. DSRSD staff hang notices on front doors 24 to 48 hours in advance of water shutoffs for impacted customers.
Posted: July 8, 2021