The design of the connection encompassed several important
considerations. First, the portion of the Lakeview Pipeline downstream of PC- 1 had to be isolated from the portion upstream
of PC- 1. Therefore, an 84 in. diameter valve was placed on the
Lakeview Pipeline at the connection. When the valve is closed,
it will force flow from PC- 1 to the Mills plant. Second, it would
have to be possible to isolate the connection pipeline from the
Lakeview Pipeline if the latter was being used to convey water
downstream to the San Diego Canal or to the downstream service connection referred to as EM- 14. Third, it was required that
EM- 14 be able to obtain flow from PC- 1 whether or not the latter was sending flow to the Mills plant. Furthermore, the head
on the downstream portion of the Lakeview Pipeline had to be
controlled so that the pipeline would not be unduly pressurized.
To meet these requirements, two 84 in. diameter valves and
a 24 in. diameter throttle valve were required. Fortunately, the
MWD had two 84 in. butterfly valves available that were rated
for the pressure. One 84 in. valve would be used to isolate the
Lakeview Pipeline from the PC- 1 connection, and the other
would be installed on the Lakeview Pipeline to prevent flow
from the connection piping making its way downstream. The
24 in. throttle valve was plumbed so that it could send water from PC- 1 downstream of the 84 in. valve or deliver water
from the upstream side of the Lakeview isolation valve.
Another element of the connection was an 84 by 84 in.
diameter wye connection with 4 in.
thick crotch plates. Since the valves
were only 84 in. in diameter, the
132 in. diameter Lakeview
Pipeline needed two eccentric reducers to accommodate the valve.
The connection has two
vaults to house the two
The Perris Pump Back Facility
also required modifications. For one thing, there was no way to
bypass the pumps to allow gravity flow. The design team proposed a full-size bypass pipeline around the pumps so that flow
could reach the Mills plant by gravity once the Bernasconi Tunnel had been lined. Because the suction line to and from the
pumps had a diameter of 60 in., a 60 in.
bypass pipeline was installed adjacent to
the pumps. This line required two 60
by 60 in. diameter tees with
1. 5 thick in. crotch plates.
A 60 in. diameter valve
was used to isolate the
line when the pumps
FLOW TO MILLS
PLANT AND SAN
FLOW FROM LAKE