The Discovery

Back in the summer of 2002, Paco and I found something strange on TerraServer, the lame-by-comparison precursor to Google Maps/Google Earth. While checking out satellite imagery of the Redding area, we found a weird Xevious-like structure located out in the middle of the woods up near Whiskeytown Lake.

We decided to go investigate, which we soon found required a long hike up the hill behind the Carr Powerhouse. What we found back there was nothing short of amazing, and every bit as interesting as we had hoped. It turned out to be a surge basin, which is used in the event that the gigantic pipes that carry water from the Lewiston Reservoir to Whiskeytown must be closed for emergency purposes. Basically, all the displaced water needs to be shot out of the pipe system in an unpopulated area somewhere, and that’s the purpose of these things. There are other weird facts about these giant concrete ‘sinks’ that are even more interesting, but I’ll get to them later.

 

eduardo_basin1.jpg eduardo_basin1.jpg
Clear Creek Basin Spring Creek Basin

 

The one on the left is the one that Paco and I found, but the one on the right is a new discovery. My good friend Miguel tipped me off to the location of this one, and it’s right near Keswick. I think an expedition is in order at some point, so click on the image and you’ll be able to see exactly where it is.

If you guys recall, Guillermo has a few stories related to these things as well. I think he mentioned that there were “several” of these things out in the hills, but so far I’ve only found these two. The ones shown above are part of the Whiskeytown system, so I’m not sure if he was referring to them or not.

The Letter

About a week ago, I wrote an email to the Bureau of Reclamation requesting more information on these things:

 

Hello,

Several years ago, I came across a “surge basin” in the hills above the Carr Powerhouse at Whiskeytown Lake – and have been curious about these huge structures ever since.

I’ve been able to find bits and pieces of information on the particular one I found, and from what I understand they are used for overspill in the event that the giant pipes they’re connected to must be closed. Interestingly enough, a friend of mine who used to work at Shasta Dam around a decade ago told me that there are two other such structures that are affiliated with Shasta Lake – and I’m wondering if this is true.

Would it be possible to get some more information on these basins?
Is it true that other ones aside from the one I found exist in the area? If so, where are they?

I’d greatly appreciate any information you can provide. Thank you for your time.

Sincerely,

Eduardo Jimenez

 

I figured that getting a response was somewhat unlikely, and that they’d probably just forward my email on to Homeland Security. However, today I was pleasantly surprised to hear from Brian Person, manager of the Northern California Area office. Here’s what he had to say:

 

Eduardo,

Thanks for the email, and your interest in the Trinity River Division infrastructure. Sheri and I recently discussed your question, and agreed that I would respond.

The surge basin you observed is connected to the Clear Creek Tunnel via a vertical shaft. The tunnel provides water to J.F. Carr Powerplant, and the shaft and surge basin provide an outlet for the tremendous dynamic energy of the water flowing through the tunnel in the event the plant must be quickly shut down. At the maximum design flow rate, 3,200 cubic feet, or just under 100 tons of water pass through the tunnel each second, and at a relatively high velocity (up to 13.5 feet per second). If there were no means for this energy to “escape” via the surge basin, the tunnel and downstream gates would have to many, many times stronger – if such a structure were feasible at the time the facilities were constructed.

The Spring Creek Tunnel, which feeds Spring Creek Powerplant south of Keswick, is equipped with a similar surge basin, though the tunnel’s carrying capacity is about 18% larger than that of Clear Creek.

I must say an important few words about safety. The plants are automated and can shut down very quickly without warning. In that event, water rises from the tunnel and into the standpipe at about the same velocity it travels through the tunnel, as described above. Any persons inside the stilling basin would be at risk for serious injury or worse.

Thanks again for your question.

Brian Person

Area Manager

 

Although I have no clue as to who ‘Sheri’ is, I certainly appreciated his reply. I thought it was kind of interesting that, toward the end, he implied that people should stay out of the basins – as if you can just walk around in there. From what I recall, the one Paco and I found was heavily protected with barbed wire fencing and stuff. In fact, I could be wrong about this – but I don’t think us common folk are even allowed up there anymore, due to all the terrorist paranoia in the air these days.

More Details

I actually got the idea to write to the Bureau of Reclamation after coming across an old blog page from 2003 that was authored by Miguel’s ex-girlfriend. To make a long story short, the two of them ventured up there shortly after Paco and I did – but had the sense to do a little more investigative work. Her blog apparently no longer exists, and all that Google coughed up was a cached version of her page – the gist of which is shown below. As you can see, the response she received reveals more details than the one I got.

 

THE CLEAR CREEK TUNNEL DISCOVERY – THE TRUTH WAS OUT THERE!

I mentioned in my last entry that I had written a letter to the Bureau of Reclamation requesting information regarding the basin we had found above the Carr Powerhouse. Much to my surprise and delight, I received a response! I most likely shouldn’t be “publishing” this person’s email so I’m going to leave his name out, but I thought you guys might be interested in what he had to say. Here is the email I received:

I am a senior control operator/Operations Supervisor at Keswick Power Plant. Our public relations person asked me to reply to your questions re: the structure you ventured upon during your hike.

The Carr power house, located at the west end of Whiskeytown Lake, receives its water via an eleven-mile long tunnel that starts at the Lewiston Dam, called the Clear Creek Tunnel. Water flows in the tunnel at up to 200 mph when the Carr power plant is at maximum capacity (generating). If the units at the Carr power plant were to be shut down through a relay action (any kind of trouble on the system or with the units), the gates that govern the water to the turbine will close in four seconds, backing up the flow of water in the tunnel. In order to prevent any damage to the tunnel, a standpipe, 16 foot in diameter, 183 feet high, is attached to the tunnel just before the tunnel splits (bifurcates) into the two penstocks you see coming down to the Carr power plant. This standpipe, surrounded by the structure to accept the water which would blow up out of the standpipe in the event of an emergency shutdown, is called the Carr surge basin.

The surge basin is capable of safely handling the volume of water as well as limiting the tunnel pressure to prevent any damage. This kind of trouble is rare, but the necessity of the surge basin is obvious.

The other structure you came upon is the Carr butterfly valve house, about one-quarter mile downstream of the surge basin. In the bottom of it, under the steel plates you wrote about, are the two large butterfly valves that can close or be closed to unwater a penstock. They are approximately 15 foot in diameter, and service one penstock each. These will close in the event of an emergency, too, but take approximately one minute to do so.

Once every week, these sites are inspected by an operator. Once every five years or so, the entire Clear Creek tunnel is un-watered to inspect it, and perform any maintenance that may be required. Back in 1990, we entered the tunnel via the standpipe at the Carr surge basin, using a giant crane. A specially equipped, diesel-powered Jeep, with large scrub brushes attached, was lowered into the tunnel, and it proceeded to scrub the entire eleven miles of the tunnel. The last time we did this, last year, we entered the tunnel through an adit, the Carr Bypass, which is a side tunnel that we can use to evacuate water from Lewiston Lake in the event that the Carr power plant is unavailable for service. It is rarely used, and in the 23 years I have been here, I don’t recall the Carr bypass being used for this purpose. It is located up the road that goes to the Crystal Creek Boot Camp (formerly the Conservation Camp). There is a really nice waterfall located approximately 100 yards behind the bypass structure.

I hope this answers your questions. If we can be of any more help, let us know.

 

I also remember Guillermo describing the same maintenance procedures mentioned in this message, and that he told us about how the guys doing the work had to wear full scuba gear or something.

Guillermo, if you’re reading this, please (re)enlighten us on what you know about these!

Update:

Here’s a photo of the Spring Creek Surge Basin I took a while ago. It’s definitely very weird, especially because it’s so remote. You hack through brush to get to the trail, then eventually come upon a clearing with a football field-sized concrete basin with a gaping mouth in the middle of it.

Spring Creek Surge Basin, Redding, CA
Click image to view larger.
Map it:  40.624009,-122.477946