The cisterns are basically an underground swimming pool, they're a holding tank.
We have over 180 cisterns and the average one is 75 thousand
gallons, some are a little bit smaller, some a little bit bigger.
They're identified, if you ever walk through the streets of San Francisco, they're
identified uniquely by a circular brick pattern and you'll see them most of the
time in an intersection. Believe it or not, those date back to the early 1800s.
They started building these cisterns and the first ones were built with bricks,
underneath they're solid brick and that's where you got the brick ring from.
The cisterns now are made with concrete and steel rebar. If there is an
earthquake they're probably one of the safest places to be if they were empty
because it's just a solid underground tank and that gives us the unique
ability, it doesn't matter if a water pipe breaks or not, it gives you the
unique ability to go over to a cistern and draft.
What we're going to do is
draft water from the cistern and we're immediately going to charge this hose
here coming off of our bumper line and we're going to flow water back into the
cistern so we don't waste any water. So right now the pump is empty, there is no
water inside the pump, there's no water inside this hard suction. You can see
it's pretty loose. So now I want to get water inside these two areas. What I need
to do is turn my primer switch to the "on" position, so now my primer switch has
powered the auxiliary pump and now I'm going to activate my prime and I'm going
to do this for a period of 30 to 45 seconds and once I notice that we're
getting some pressure water coming into this hose I'm going to dial up my
throttle on the fire commander so that we can get pressure and then I'm going
to open my bumper discharge so these guys can charge line.
Okay!
So now I have good pressure here so I'm going to go ahead and charge the bumper line.
Give a little bit more pressure.
And as you can tell now, we're flowing water back into the cistern.
So now I'm just watching this dial, just to make sure I have good pressure.
I'm keeping an eye on this hard suction hose, making sure there's still water coming into it.
Once I realize that I'm getting short on water, now I want to alert my
crew and make arrangements to get water from a different source.
So our auxiliary water supply system, which was put in after the 1906
earthquake, is completely independent from the domestic supply system.
It is gravity fed and it doesn't have any branches off it so it's just main
ductile iron steel coming through the streets, so there's less chance of a
break and if it does break it's divided up into zones. So we have motorized
valves; if one zone starts to leak we can close that zone off and we can still get
pressurized water everywhere else. That has basically three main components to it.
The first one's Twin Peaks reservoir, which is roughly 10 million gallons of
water up at Twin Peaks elevation and then it drops down to Ashbury and
Ashbury tank is about 500,000 gallons and then it drops down to Jones Street
tank which is 750,000 gallons of water, so there's basically three different
zones and if you'll notice the big hydrants are painted three different
colors–blue, red, and black–to clarify which zone you're in. So if we're in the
lower zone and we have a big fire and we use the demand, just like a few months
ago when we were at Mission Bay and we had the big fire, we exceed the demand at
Jones Street tank then we'll put in Ashbury tank and that would increase the
pressure and volume and when we have a big, big demand we would also increase it
to Twin Peaks so we'd have all three zones coming into the lower zone, which
would give us much more volume and pressure. So the auxilary water supply
also has two pump stations; one of the pump stations is the building we're in,
this is Pump Station One, which is now our Fire Department headquarters
the other one is Pump Station Two, which is over by Aquatic Park. So once those
tanks are emptied out, we say, okay, now we're out of water–well, not the case.
We turn on these pump stations and both of these have tunnels that run to the bay
and they suck up the seawater and they can pump it throughout the system.
So we have two pump stations that would have an endless supply of water. We also have a
fire boat and along the bay we have five fire boat manifolds and the fire boat
can pump into the system and also charge all the hydrants from the fire boat.
With a city that's prone to earthquakes, you can never be too
redundant and we have a lot of redundancy. So if one thing were to break
in an earthquake, we could go in a different direction just to keep the
citizens safe and make sure we put a fire out.
you