California water district upgrades control system

Californians have always been faced with the problem of how best to conserve, control and move water. California has a wide diversity of climactic and geographical contrasts. The northern part of the state, with its alpine forests receives as much as 100 inches or more of rain per year, while the central and southern parts of the state range from arid desert to fertile farm land with some areas receiving fewer than two inches per year. Population centers have grown up in locations where there is not a sufficient water supply. The central valley, running from Sacramento to Bakersfield, contains some of the most fertile farm land in the world, most of which is dependent on irrigation. Because of this need to conserve, control and move water to areas of need, California has developed the State Water Project, the largest state-built water development project in the U.S.

The Cawelo Water District is a small part of this statewide water project. Located in the southern portion of California’s fertile San Joaquin Valley, the Cawelo Water District supplies irrigation water for over 45,000 acres of crops including grapes, citrus, almonds and pistachios.

In 1997, the Cawelo Water District decided that the level of reliability was not acceptable in their current system. Parts were no longer available for their legacy system and buried wire was degrading with age. So, they decided to upgrade their system to allow remote control of facilities, monitoring of power usage and quality, and to enhance the ability to perform load shifting for remote facilities.

"The water district needed a name-brand solution with local support," says Danny Burns, Operations Manager for Prousys Inc., the system integrator chosen to construct the new system. "We recommended Allen-Bradley hardware."

Allen-Bradley SLC processors were installed to replace the aging Westinghouse PLCs at each of the five remote well sites. In order to monitor power usage and detect anomalies in the Multilin PQM Power Monitors, a ProSoft Technology Modbus Communication Module (3150-MCM) was installed in each processor.

"This is a perfect example of how ProSoft modules are used everyday to connect Allen-Bradley hardware with other networks," said Scott Sibenac, Regional Sales Manager for ProSoft. "We receive numerous requests on a daily basis for modules in the water/wastewater industry. Because our modules are designed to be used as ‘in-rack’ solutions for Allen-Bradley processors, it is a cost-effective way for plant managers to use their existing Allen-Bradley equipment with other network’s protocols."

A SCADA Master Control system was also installed consisting of an Intellution Fix/DMACS HMI and an Allen-Bradley SLC 5/05 with two ProSoft DF1 Communication Modules (3150-DFM) in order to poll all of the five well sites, three pump stations, four reservoirs and five check stations via a Data-Linc SRM6000 Radio and LLM-100 Modem.

Redundancy is a key factor in most water systems. Prousys installed and configured a second Intellution HMI to provide control redundancy. In the event of a failure in the primary controller, the system switches to the backup, ensuring seamless control in the plant.

"In other words," states Burns, "The system will keep right on running if the HMI goes down."

The system’s three pump stations, containing pumps ranging in size from 500 to 1,000 HP, are controlled according to the levels in the associated wells. The precise operation of the system depends on the accurate measurement of system levels and flows across the entire water system. Flow and level meters relay these measures back to the central control room for monitoring and control. Allen-Bradley Panelview 550s were installed at each of the three pump stations.

"The new system now gives the water district full control of all remote sites," said Burns. "The SCADA system can now track station flow rates, overflow events, well level, in-flow and out-flow. They also have the capability to detect numerous system failures including power, high/low voltage, phase imbalance, high/low amperes, frequency, load factor and low water level. Since the ProSoft modules communicate over the backplane with the Allen-Bradley processors, they were critical to the success of this project. ProSoft provided the ‘missing link’ in the communication chain, seamlessly allowing connectivity between these differing networks."

This new upgrade was not the first time the Cawelo Water District has made news. In 1996 they received an Award for Distinguished Service in Environmental Planning at the International Development Research Council World Congress. The project was a unique endeavor, which allowed excess water produced from Texaco’s oil production operations in the Kern River Field to be used to help provide nearly 15 million gallons of irrigation water daily to the Cawelo plant.

"This project clearly demonstrates that something good for the environment and something good for business, do not have to be mutually exclusive," said Dean Bears of Texaco.

The Cawelo Water District upgrade was completed in December of 1999. New reservoirs and wells are still being added to the system, all using the Allen-Bradley/ProSoft Technology solution.
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