Wood City Progress | water world

The city of Samoa in northern California was once a bustling logging town on the northern peninsula of Humbolt Bay. The town is also famous for the logging camp-style Samoa Cookhouse, a community staple since 1893.

The Samoa Pacific Group bought the city of Samoa in 2001 to redevelop it by providing essential infrastructure and housing to preserve the coastal city.

The redevelopment plan includes a light industrial park, public recreation, a new single-family residential development, an affordable housing project, and overhauls to the city’s drinking water and wastewater infrastructure. The revitalization of the area is part of an effort to make Samoa its own official city.

The peninsula’s infrastructure, in place since the 1920s, was in dire need of repair. Upgrades were mandated by the California Coastal Commission and Humboldt County, which resulted in the construction of a new sewage treatment plant, as well as a water storage tank in case of power failure. current, earthquake or tsunami. The effort also included a new booster pump station for drinking water distribution.

The potable water supply is routed through the storage tank to a new booster pump station, which Romtec Utilities designed and supplied, and the control building by sister company Romtec Inc.

The development and management of the project was provided by the Danco group; the infrastructure design was carried out by the California Engineering Company; the review was conducted by EsGil on behalf of Humboldt County; and many others such as Aqua Sierra (electrical contractor) and Mercer-Frazer (contractor) built the booster station.

Romtec Utilities provided the developer and owner with a single source for the complete design, supply and commissioning of this fully integrated pump station and building. This offer provides significant financial value to the developer. It also assured the owner that with the full support of a single entity (Romtec), the system would be operational as planned.

The booster station is designed to accommodate progressive housing development and community fire suppression. It draws water from an adjacent 300,000 gallon water storage tank and increases flow rates for domestic residences and fire hydrants. It is designed to meet immediate flow requirements and anticipated future flows using American-Marsh vertical turbine pumps.

There are three 264-gallon reservoirs to prevent the system from short-cycling during spurious flow demands and to suppress transient pressure spikes. Water pressure is maintained during power outages by an emergency generator installed inside the control building, adjacent to the pumping station.

The built-in booster station uses a variety of Val-Matic valves, including 2000 series butterfly valves, 1400 and 1800 series check valves, and 15A air purge valves. The station also incorporates a Ross 20WR pressure relief valve.

There are two three-horsepower Ebara pumps for domestic flow that pump up to 53 gallons per minute (GPM). There are also two larger 75 HP Ebara fire flow pumps that can pump up to 1,500 GPM for high flow rates. The multi-stage configuration of these stainless steel pumps allows for ample pressure capability during the pump selection process.

Programmable pressure switches (EPS25) are installed on the inlet and outlet of each pump to guarantee adequate suction pressure and not excessive outlet pressure. A pressure transducer from Endress+Hauser (PMP 51) monitors the water pressure entering and leaving the system. An Endress+Hauser flowmeter (Promag L 400 series) measures the velocity and volumetric flow of water flowing through the system.

The station’s high-flow pumps include Grundfos vertical in-line centrifugal pumps. They use a single turbine but are designed to deliver higher flow rates.

“What makes this booster station different is that it has also been programmed to monitor the level of the storage tank and allow actuation of a fill valve,” says Kevin Bogan, Mechanical Engineer at Romtec Utilities. “The control panel receives a signal from a level transducer on the tank and, if the tank level is low enough, sends a signal to an actuator on the fill valve to fill the tank at specified times in the evening. Level information and valve position are also available remotely via a SCADA system.

The control panel designed by Romtec Utilities incorporates closed-loop control, which monitors the pressure transmitters located at the discharge and suction ends. This is to monitor the supply level/pressure as well as the demand level/pressure. As the discharge pressure decreases (indicating an increase in demand), the system will begin to pump. More pumps will come on stream as demand continues to increase.

“The design is state-of-the-art,” said Dale Unea, fire chief and chief maintenance operator for the Peninsula Community Services District. “Everything is computerized, the PCL does 90% of the work and I just make sure everything does its job. It pretty much works on its own.

The desired pressure will be maintained with PID (Proportional, Integral, Derivative) control. Using variable frequency drives (VFDs) to control pumps is a very important process for PID control. VFDs match the speed of the pumps to optimize performance and control pump buildup or sluggishness. Often used in applications where the level must remain constant, VFDs increase the power of the pumps when the demand is high and decrease the power when the demand is low. ABB ACS580 VFDs control the speed of the pumps to produce the desired discharge pressure when the water demand changes.

Some of the specific technologies used on the control panel include an Allen-Bradley CompactLogix Programmable Logic Controller (PLC) which is programmed to control the entire process. It also provides operational, diagnostics, and alarm/fault information. An Allen-Bradley PanelView Plus 7 human-machine interface acts as a computer screen, displaying all relevant information within the controller.

Finally, the station’s Cummins diesel generator is a 150D6D model rated at 150 kW. The Cummins automatic transfer switch is an OTEC model with a 400 Amp rating.

“It’s just the marriage of the new water system with the old, removing the old part of the mill system and updating it,” Unea said. “He brings everything into the 21st century. The addition and phases of new homes, businesses and community revitalization is what has come full circle – and brought me on board. »

The Samoa City Booster Station is an excellent example of a city investing in its infrastructure and potable water system to meet the needs of future growth and continued revitalization. WW

About the Author: Josh Gaunt is a contract writer with Romtec Utilities: a designer, manufacturer and supplier of pumping systems.

Posted in water world review, August 2022.

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