three-dimensional survey of the pipeline and found deflections
in excess of 4 in. at more than 660 locations. Deflections of
12 in. were found at four locations.
In view of these problems, the MWD had planned to install
a steel liner to address the leaking joints and deflection and to
enable the pipeline to accommodate a higher pressure. The proposed liner would be designed to resist the maximum possible
hydraulic pressure in the Inland Feeder, which has a hydraulic
grade line (HGL) of 1,937 ft. By contrast, the Lakeview Pipeline
had a significantly lower HGL, just 1,440 ft.
Upgrading the Lakeview Pipeline would also require renovating the 1 mi long Bernasconi Tunnel, which connects to the pipeline
near Lake Perris. This 11 ft diameter
concrete-lined tunnel, which has minimal reinforcing at the portals and no
reinforcing in its main body, was originally designed to resist a 1,440 HGL,
or approximately 50 ft of head. Because any increase in pressure in the
Lakeview Pipeline would mean higher pressures in the Bernasconi Tunnel,
the tunnel also was to be lined with
steel pipe to resist the higher head.
After lining the Lakeview Pipeline
and the Bernasconi Tunnel, the MWD
planned to connect the Lakeview Pipeline and the Inland Feeder at an existing pressure control (PC) structure referred to as PC- 1. This structure regulates the flow of water
through the Inland Feeder to its target destinations, controlling
flow and pressure. PC- 1 can be configured to deliver flow from
the Inland Feeder to Diamond Valley Lake or the CRA.
PC- 1 controls the flow of SWP water to Diamond Valley
Lake or the CRA with the aid of six motorized 54 in. vertical
sleeve valves. Flow though these valves discharges into a large
steel outlet pressure chamber. Each sleeve valve controls the
rate of discharge into the chamber and safely reduces the pres-
sure of the water. The water in each chamber can then be di-
rected either to the CRA, which has a 1,480 ft HGL, or to Dia-
mond Valley Lake, which has a 1,784 ft HGL.
Two of the sleeve valves were originally constructed with
discharge pipes that were to be connected to the Lakeview
The pressing nature of the drought forced the MWD to
 Civil Engineering november 2015
ONCE THE CONNECTION WAS
METROPOLITAN WATER DISTRICT OF SOUTHERN CALIFORNIA SERVICE AREA
MADE, THE MWD WOULD
HAVE ANOTHER OPTION FOR
DELIVERING WATER FROM
DIAMOND VALLEY LAKE TO THE
MILLS PLANT, NAMELY, THE
PERRIS PUMP BACK FACILITY.