Chemical Find Shuts Down 2 LA Reservoirs (600 MILLION gallons to be drained)

[Ghost in the Machine]

Chemical Find Shuts Down 2 LA Reservoirs
Published: 12/14/07, 11:26 PM EDT
By ANDREW DALTON

LOS ANGELES (AP) - Two reservoirs that supply drinking water to parts of the nation's second-largest city have been shut down and will be drained because a rare sunlight-fueled chemical reaction tainted them with a cancer-causing chemical, utility officials said Friday.

The Los Angeles Department of Water and Power plans to drain 600 million gallons from the open-air reservoirs early next year, a process that will leave them out of action for three to four months amid drought conditions, department spokesman Joseph Ramallo said in a statement.

The two reservoirs supply only about one-third of 1 percent of the city's annual water consumption, or about the amount the entire city consumes in a day, Ramallo said. The closures haven't left the city short of water because demand decreases in the fall and winter, he said.

The chemical, bromate, is dangerous only after long-term consumption, officials stressed.

"There is no immediate health risk," Ramallo's statement said.

http://www.att.net/s/editorial.dll?pnum=1&bfromind=7401&eeid=5583968&_sitecat=1522&dcatid=0&eetype=article&render=y&ac=-2&ck=&ch=ne&rg=blsadstrgt

[alfredo]

1. So what is going to keep it from happening again?

[Ghost in the Machine]

2. Maybe they won't add chlorine??

:shrug:

I wonder how they could treat that water and fix it??Couldn't they filter it, boil it, filter it again and bottle it for sale or use it somewhere else?

Otherwise, what are they going to do with it? Where are they draining it to? Back into the groundwater or into the storm drain systems or something? It's gotta go somewhere, right?

[alfredo]

3. Lot of the chemical will be in the muddy bottom. I bet they find a lot

of anti depressants in the water, maybe some THC, and other fun things.

[nebenaube]

4. most of it will evaporate.... the bromate will just lay there...n/t

[alfredo]

5. Kinda like I did today.

[necso]

6. So where did the bromine in the bromate come from?

Was it used to "chlorinate" the water instead of chlorine?

[TheMadMonk]

7. Probably methyl bromide, Used to fumigate soil.

It's also a nasty ozone depeleter. It's unfortunately also about the only chemical suitable for the task it's used for.

[necso]

8. Possibly,

and maybe it wasn't methyl bromide itself in the water, but rather bromine (as ions, in other compounds) resulting from the breakdown of methyl bromide. (This gets interesting*.)

Bromine ions (from any source) could react with either chlorine dioxide (plus sunlight) or ozone to form bromate. (But generally you should be careful about using either to treat water if you know there's a lot of bromine in it.)

However, the methyl groups (if methyl bromide is involved: ie, if it hadn't broken down) might have combined with something, leaving some indicator (although perhaps an unstable/transient one).

It'd be nice to know that the problem isn't larger -- and that it'll be prevented in the future. Which brings us back to where did such concentrations of bromine come from.

*: It (apparently) turns out that while methyl bromide (CASRN 74-83-9) is a candidate for being considered (by the EPA) as a drinking water contaminant (http://www.epa.gov/safewater/ccl/ccl2.html) and having limits set for it, currently it isn't considered a contaminant -- hence there are no federal limits. (Although the issue may be more leftover bromine from the breakdown of methyl bromide than methyl bromide itself.)

Moreover, methyl bromide is soluble in water at a level many times greater than that required to produce the EPA limit for bromate, which is 10 µg/L. (I've found a range of figures for its solubility on water: 13.4 grams/L and 16.1 grams/L at 25C for example.) However, supposedly it evaporates quickly from water (www.inchem.org/documents/sids/sids/methbrom.pdf -- if you can believe this).

But this doesn't mean that bromine (as ions, in other compounds) from broken-down (not evaporated; it apparently photodegrades for one path) methyl-bromide couldn't exist at levels (and stay dissolved long enough) in water sufficient to create 10µg/L (and above) of bromate.