HAZARDOUS WASTE DIVISION

MTBE FAQs - Frequently Asked Questions
What You Should Know

You may have read or heard about methyl tertiary-butyl ether (MTBE) concerns in the Lake Tahoe area. Problems associated with MTBE are very complex and are currently affecting the entire state and much of the country. This fact sheet is intended to answer some questions about MTBE and to let you know what is being done to address MTBE impacts. This informational sheet is being mailed to all improved parcels within the El Dorado County portion of the Lake Tahoe Basin including the City of So. Lake Tahoe.

What Is MTBE?

MTBE, methyl tertiary-butyl ether, does not occur naturally. It is a colorless, flammable liquid with a strong odor that has been used as a gasoline blending component since 1979. Since the early 1990's, MTBE has been increasingly added to gasoline sold in California, now up to 11% by volume, to make gasoline burn more completely and, therefore, reduce harmful air emissions.

Why Was MTBE Introduced as a Gasoline Additive?

Air quality standards mandated by the United States Environmental Protection Agency (USEPA) and California Air Resources Board (CARB) require gasoline to contain chemicals called oxygenates, one of which is MTBE, to reduce air pollution. California gasoline producers are subject to gasoline blending requirements at both the federal and state level as dictated by the Federal Clean Air Act and CARB's Cleaner Burning Gasoline regulations. In response to these regulations, gasoline producers in California have invested over $4 billion to redesign their refineries to produce MTBE as a principal blending component to meet gasoline regulations. MTBE is credited with contributing to major air quality improvements in the state, reducing emissions by 3 million pounds every day which is equivalent to taking 3.5 million cars off the road.

What is the Concern Regarding MTBE?

While MTBE may be good for air quality, it now appears to be very bad for other parts of the environment; especially ground water. Over the past few years, monitoring has detected MTBE in lakes, streams, and ground water. During the summer of 1997, the US Geological Survey found detectable levels of MTBE in Lake Tahoe to a depth of 90 ft. If MTBE gets into a drinking water supply, it creates a bad smell and may pose health concerns. As an example, the City of Santa Monica had to close down almost all their supply wells due to MTBE contamination and now have to buy drinking water from other sources.

How Does MTBE Get into Water Supplies?

Because gasoline is so widely used, MTBE finds it's way into almost every part of the environment. MTBE can get into water supplies from gasoline leaks, storage tanks, pipelines and spills. It may also get into surface waters from boats and personal water craft. MTBE evaporates into the air, but it is believed that most MTBE in air breaks down to other components. However, when MTBE gets into ground water, it does not readily evaporate or break down. It dissolves in the ground water and can move through an aquifer in the form of a "plume".

What Are the Problems with MTBE in Drinking Water Supplies?

The unpleasant taste and odor of MTBE can be detected at very low levels in drinking water. MTBE is often described as having a turpentine-like smell and taste. Initial studies show consumers can detect it in drinking water at anywhere from 15 to 40 parts per billion (ppb). Primarily for taste and odor considerations, the USEPA has established a "Drinking Water Advisory" of 20 to 40 ppb (parts per billion). The California Department of Health Services has established an "Interim Action Level" of 35 ppb. The USEPA has advised a level of 70 ppb for safe drinking water. However, the California Office of Environmental Health Hazards Assessment has proposed a Public Health Goal of no more than 14 ppb in drinking water. MTBE is considered a "possible human carcinogen" by EPA, but little is known about the long-term health effects of MTBE in drinking water.

What Are the Environmental Effects if One Gallon of Gasoline is Spilled?

If it is assumed that 14 parts per billion is an acceptable limit for MTBE in drinking water, one gallon of gasoline could contaminate almost 8 million gallons of water making it unfit to drink. It would take less than a teaspoon of gasoline to contaminate a 10,000 gallon swimming pool to a level of 14 parts per billion of MTBE!

What's the Answer to the MTBE Problem?

So far, nobody has the answer. Politicians, regulators, environmentalists, gasoline producers, and others all have their own opinions. Clearly, using MTBE in gasoline to help mitigate one environmental concern, i.e., reducing air emissions from vehicles, has led to possibly a much larger environmental tragedy--the contamination of our drinking water. This issue will not be settled easily or quickly, nor will it be settled at a local level. In the mean time, the best we can hope to do is work on controlling the release of gasoline from leaks, spills, and emissions.

State and Federal Underground Storage Tank Laws and Regulations

Under general guidance from the State Water Resources Control Board, the El Dorado County Environmental Management Department is mandated to enforce the California Underground Storage Tank Law and Regulations which require all fuel stations to perform on-going underground tank and piping testing. More importantly, by December 22, 1998 (the state and federal deadline), all fuel stations are required to upgrade their underground storage systems with corrosion resistant double wall tanks and piping, overfill protection and leak detection devices. This design is very simple--if the inner tank or pipe develops a leak, the outer shell will contain the fuel and the leak detection system will notify the operator of a problem. By state law, the Department is required to perform inspections of each UST system at least every three (3) years.

Are there Sites in So. Lake Tahoe Which Have Been Contaminated by Leaking Underground Storage Tanks?

Yes, along Hwy 50 there are several areas where past underground tank releases have been identified during the upgrading of facilities, i.e., an inspection and testing of the old tanks and soil within the excavation have revealed past releases. When a gasoline leak has been detected, the Department orders the removal of the contaminated soil and an immediate site investigation to determine possible off site contaminant migration and if groundwater is impacted. Confirmed groundwater contamination cases are referred to the lead agency for action--the Lahontan Regional Water Quality Control Board. Lahontan will order on and off site monitoring wells to determine the lateral and vertical extent of contamination. Based on those findings, remediation of the contamination will be required.

Why Hasn't the County Closed Sites Which Have Historically Leaked?

Sites with evidence of past contamination have upgraded their tank storage systems with double wall containment and leak detection programs. We are dealing with "old discharges" and the new upgraded tank systems are not likely contributing to the existing problem. However, the Department continues to perform on-going inspections of all UST facilities to monitor the effectiveness of the upgraded systems and to insure compliance with the "double containment" deadline of December 22, 1998. There has been a recent media reference claiming that "...new tank systems can leak up to 2.5 gallons a day and still be "in compliance" with the new regulatory requirements..." That statement is simply not accurate. Rather, this is in reference to the expiring UST regulations for single walled tanks which provide for a temperature correction factor for tank integrity tests as gasoline expands and contracts. By regulation, tank integrity testing is required on all single walled tanks until the site owner/operator upgrades the facility to the new double wall and leak detection standards. Again this deadline is December 22, 1998. After this deadline, single wall tanks are not allowed. The new double wall tanks and piping systems requirements do not allow any "leak" or "temperature correction" factor.

After January 1, 1999 and pursuant to state law, gasoline tanker trucks and other wholesalers cannot re-fill underground storage tanks with motor vehicle fuel which do not have an Upgrade Compliance Certificate and Fill Pipe Tag.

What Are Your Local Gas Station Owners Doing to Help?

The owners and operators of UST systems are responsible for the daily operation of their facilities. They are required to by law to report any unauthorized releases of fuel products, failures in their monitoring systems and to inform the Environmental Management Department of any repairs to their systems. It is their responsibility to operate and maintain their facility in a safe manner, prevent fuel spills and to properly cleanup any accidental spills. They must also order the correct amount of fuel to be delivered, and monitor the delivery of fuel to their tanks. They are also required to have spill plans and to have cleanup materials on site to contain any spill.

What Can You Do To Help?

Even the smallest spill of gasoline has the potential to contaminate thousands of gallons of water. Consumers must not overfill their tanks when fueling vehicles, boats, snowblowers, lawnmowers and other gasoline powered engines. Never use gasoline to kill weeds. Old gasoline can be taken one of our household hazardous waste (HHW) facilities located in South Lake Tahoe, Diamond Springs and El Dorado Hills. For locations and hours of permanent HHW facilities, click here. There are also household hazardous waste special events held periodically throughout the year, the times and places can be found on the EMD Event Page.

What is the Future of MTBE?

Obviously, this is a critical issue of state and national importance. Major oil companies have invested billions of dollars modifying their refineries to produce MTBE for cleaner air, but as a result, the use of MTBE may be compromising our groundwater and lakes. Other oxygenates including ethanol should be closely examined as a potential alternative. The So. Tahoe Public Utility District is currently conducting a "MTBE Free" campaign and we urge you to back them up. The District can be reached at 544-6474.

Other Local Issues and Drinking Water

Between 1952-1975, the Meyer's Landfill located near the intersection of Elks Club Dr. and Pioneer Trail was open to the public and was the only regional landfill in the So. Lake Tahoe Basin. This landfill served the residents of all three jurisdictions including the City of So. Lake Tahoe and the Counties of El Dorado and Douglas County, NV. The site was permanently closed in 1975 and refuse was then exported out of the Basin to Gardnerville, NV. Over the past year and in a cooperative effort with the US Forest Service, Lahontan Regional Water Quality Control Board and the three jurisdictions, an aggressive site investigation has ensued to determine if there is subsurface groundwater contamination. The investigation continues, but vinyl chloride has been detected in several monitoring wells. Recent analysis of new off site monitoring wells demonstrates that the vinyl chloride "plume" is not threatening any of So. Tahoe Public Utility District's wells at this time. Because the public readily uses areas adjacent to the landfill for biking, jogging and snowmobiling, we request that you stay clear from the landfill footprint and Sierra Pacific Power Substation areas. There are over 20 monitoring wells in this immediate area which can be damaged or inadvertently become a safety hazard to individuals attempting to recreate in the old landfill area.

If you have any questions, please contact Virginia Huber in So. Lake Tahoe at 530.573.3450 or in Placerville, Gerri Silva at 530.621.5300.