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Crescenta Valley Water District (CVWD) provides drinking water to approximately 32,000 customers in the foothills of the San Gabriel Mountains, between the San Fernando and San Gabriel valleys. Approximately 60% of the district’s water demand is supplied by groundwater from the Verdugo Basin, which is drawn from twelve wells. During our 2004 watch, CVWD discovered low levels of methyl tertiary-butyl ether (MTBE) in the groundwater. In August 2006, elevated levels of MTBE were detected in Well 7, resulting in Well 7 being shut down.
The Crescenta Valley Water District is concerned about MTBE in the water supply and has taken extraordinary steps to ensure that customers are provided with the highest quality water today and in the future. Although MTBE has been detected in wells, the water delivered to customers has been treated to meet all Federal and State standards, as well as our own stringent criteria. Groundwater Wells that do not meet our standards have been voluntarily taken out of service.
Methyl tertiary-butyl ether, also known as MTBE, is a chemical compound that is manufactured by the chemical reaction of methanol and isobutylene. It is a gasoline additive used to reduce emissions from vehicles but can be transmitted to wells and reservoirs through leaking underground storage tanks, spills and run-off. MTBE is no longer used due to concerns throughout the country about its impact on ground water. At low levels, MTBE has an odor similar to turpentine, and can cause water to have an unpleasant taste and/or odor. The state of California has an established a criteria for MTBE of 13 parts per billion in the groundwater based on health considerations and a secondary standard of 5 parts per billion based on taste and odor.
MTBE is believed to have entered the water supply from leaking underground storage tank systems including underground lines that contained gasoline and/or from surface spills at gas stations. Once in the ground, MTBE behaves differently from other gasoline constituents such as benzene . Unlike petroleum hydrocarbons, it is highly water soluble, not easily absorbed into soil, and is more resistant to biodegradation. Thus, with widespread use, MTBE has the potential to occur in high concentrations in groundwater, travel far from leak sources, and accumulate to become a concern for the entire region.
CVWD will be installing a granular activated carbon (GAC) water treatment system to remove trace amounts of MTBE from the wells. This, along with the removal of MTBE from the soil at contaminated sites, will ensure the continued purity of the water in the Verdugo Basin. To accomplish these goals, the District has created a Verdugo Basin MTBE Task Force that meets on a bimonthly schedule to discuss issues related to the situation between and among regulatory agencies and the potentially responsible parties. The task force is a cooperative work group that provides guidance on treatment and removal. Information from the meetings will be added to this site as it becomes available.
Leaking petrol storage tanks and spillage have caused MTBE to get into groundwaters in the USA. Although it is not very toxic, it is not very biodegradable either, and has a strong taste and smell, noticeable at the 15 parts per million level. There is now a strong movement to ban it from petrol, in California in particular.
By an acid-catalysed addition reaction between methanol and methylpropene. In 1994, MTBE was the 18th most important chemical produced in the USA.
CH3OH + CH3C(CH3)=CH2 --> (CH3)3C-O-CH3
| Date : 5/7/2007 |
Well Avg.
(ug/l) |
Glendwood
(ug/l) |
Mills
(ug/l) |
*DLR
(ppb) |
*MDL
(ppb) |
| ND |
0.49 |
0.29 |
0.5 |
0.13 |
| Date : 5/8/2007 |
Well Avg.
(ug/l) |
Glendwood
(ug/l) |
Mills
(ug/l) |
*DLR
(ppb) |
*MDL
(ppb) |
| ND |
0.49 |
0.29 |
0.5 |
0.13 |
| Date : 5/9/2007 |
Well Avg.
(ug/l) |
Glendwood
(ug/l) |
Mills
(ug/l) |
*DLR
(ppb) |
*MDL
(ppb) |
| 0.25 |
0.25 |
0.25 |
0.25 |
0.25 |
| Date : 5/17/2007 |
Well Avg.
(ug/l) |
Glendwood
(ug/l) |
Mills
(ug/l) |
*DLR
(ppb) |
*MDL
(ppb) |
| 0.25 |
0.35 |
0.45 |
0.55 |
0.65 |
*DLR – Detection Levels for Purposes of Reporting
*MDL – Method Detection Limit
Environmental Protection Agency
http://www.epa.gov/mtbe/
Listing of links to information about MTBE
http://www.epa.gov/mtbe/clean.htm
Discussion of clean up and treatment of MTBE
Department of Health Services
http://www.dhs.ca.gov/ps/ddwem/chemicals/MTBE/mtbeindex.htm
Lawrence Livermore National Laboratory
(University of California Lawrence Livermore National Laboratory):
http://www.llnl.gov/str/Happel.html
Case Study of Santa Monica and MTBE
http://www.komex.com/industries/casestudies.stm
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