Metropolitan Water District approves upgrades to Diamond Valley Lake monitoring

The Metropolitan Water District of Southern California will be upgrading the geodetic deformation monitoring system at Diamond Valley Lake.

The board voted Sept. 12 to approve a $748,353.67 procurement contract to Allen Instruments and Supplies, while also authorizing the upgrades, finding the project categorically exempt from California Environmental Quality Act review and appropriating $1,900,000 for all aspects of the project.

Diamond Valley Lake was completed in 2000, and it is Southern California’s largest surface water reservoir with a storage capacity of 810,000 acre-feet. The reservoir provides emergency storage in the event of a major disaster, carry-over storage to supply water under drought conditions and seasonal storage to meet annual demands of MWD member agencies. The lake was formed by the creation of three rock-filled earthen dams.

The dams are monitored continuously by the monitoring network that includes the geodetic deformation monitoring system, which transmits real-time displacement data to MWD’s administrative headquarters in Los Angeles and to the MWD operations control center in Eagle Rock. The monitoring network also includes weir level sensors, strong motion accelerographs and an automated data acquisition system. The data collected by the geodetic deformation monitoring system provides early indication of a potential problem within the dam embankments and foundations. The existing geodetic deformation monitoring system consists of 487 survey prisms installed on the crests and downstream faces of the dams and forebay, nine robotic total stations which measure movement in the positions of the prism and provide more than 11,000 measurements each day and nine continuously operating reference stations which function as survey benchmarks and provide reference points to the robotic total stations in order to calculate the three-dimensional positions of the prisms.

Much of the geodetic deformation monitoring system equipment has deteriorated over its 17 years of continuous operation; the manufacturer no longer supports the software the system uses, and spare parts have become more difficult to obtain. In 2016, the district approved procurement and installation of upgraded weir level sensors and strong motion accelerographs, and the design of a new geodetic deformation monitoring system has been completed. The procurement of nine robotic total stations, nine continuously operating reference stations, and associated equipment for the geodetic deformation monitoring system was advertised for bid, July 7.

Two bids were received by the July 20 deadline with the $748,353.67 proposal from Allen Instruments being the lower amount. The Anaheim firm was found to be in compliance with the specification requirements. The bid amount includes sales tax.

MWD staff will install the geodetic deformation monitoring system upgrades. The work will include removing the existing geodetic deformation monitoring system, installing the new system along with supporting solar panels and radio antennas and startup and testing activities. The $725,000 cost for the MWD work is included in the $1.9 million total budget, as is $83,000 for procurement of related materials including the solar panels, $78,000 for contract administration and project management, $50,000 for preparation of record drawings and $215,646.33 of contingency budget. The cost to procure of the solar panels, batteries, battery controllers, fuses, cables and enclosures is below the threshold which would require MWD board approval, so MWD general manager Jeffrey Kightlinger has the authority to award those procurement contracts administratively. A procurement and installation contract for an upgraded automated data acquisition system will be a board action when MWD is ready for that phase of the monitoring network upgrade.

The installation of the geodetic deformation monitoring system is expected to be complete in March 2018.

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