Tuesday, February 15, 2011

Capital costs, desalination, understanding hydrology

Might not sound like interesting stuff, but the above is what I found interesting from today's February 15 meeting. Planned sales of recycled water will not recover the capital costs of building the water treatment facility. This might not be totally unusual in the world of water, but I think it makes it difficult to compare costs of various options - should we invest in recycled water versus invest in conservation, say - if we don't account for all costs. Also, I understand that water retailers want to tap into and sell recycled water. I'd be concerned if, among other things, they got the water at prices that didn't cover capital costs. We'll find out.

Desalination has been treated as a subset of recycled water. It does use similar technology, but everything else about it is different (and worse). I'd like to see it separated out from recycling. There's the interesting issue of whether cancellation of it might damager relations with partner agencies, but I also wonder if there are people in those partner agencies that have the same concern that I'm expressing.

There are apparently some water rights issues related to water recycling. Not sure I understand that yet.

Finally, I would like to better understand how flood analysis is done. I think that might help understand natural flood control and how climate change effects on snow line might affect flooding. I'd also be interested in seeing predictive uses of flooding models.


Thursday, February 3, 2011


I was chagrined to learn recently that we may, emphasis may, have a problem with chromium-6 in the Water District.

The Environmental Working Group came out with a report in December that found hexvalent chromium (chromium-6) in many US cities, including San Jose. We had a Water District Board meeting the next day that said the District hadn't found any in its tests from our water treatment plants. However, the District went back through its records and informed us that it had subsequently found testing records for groundwater. The treatment plants only get surface water, but groundwater could be contaminated from natural sources, and that appears to be the case here. Making things worse, the state has significantly reduced the proposed safety level to one that's extremely low, 0.02 parts per billion, something that most labs can't even test.

The good news, such as it is, is that the proposed levels are only proposed, there is no existing level, the District is not in violation of any regulation, and the levels that are ultimately considered appropriate may not turn out to be as strict as first thought.

On the other hand, the levels found in groundwater were a median of 1 part per billion, with a high of 23 parts per billion. Obviously, that's a far cry from .02 ppb. We don't know where the official level will ultimately end up, but we may have a problem.

Anyway, we talked about it at the February 1 meeting, Item 5 (although not until near the end of that item, close to the end of the day).

Unrelated item from that same meeting was Item 4, water treatment. It occurred to me when I looked at the map that our west side treated water system could be connected fairly easily to the Hetch Hetchy water system in Mountain View, and since Hetch Hetchy is connected to our east side treatment system in Milpitas, we'd have a (somewhat) interconnected treated water system. Might be something worth investigating.