| |
Good
afternoon Chairman Gillmor and members of the Subcommittee, I am Patricia Ellis,
a hydrologist with Delaware’s Department of Natural Resources and
Environmental Control, Underground Storage Tank Branch.
I am pleased to appear today on behalf of the National Ground Water
Association, a non-profit professional society and trade association for the
ground water industry that promotes the responsible protection, utilization and
cleanup of our nation’s ground water. Our
membership includes both public and private sector ground water scientists,
engineers, and hydrologists across the country.
I
am here today to present an overview of the extent of MTBE (methyl tertiary
butyl ether) ground water contamination in the United States.
I present this data as scientist employed by the State of Delaware as
well as my experience from being a member of the EPA’s Blue Ribbon Panel on
MTBE.
Background
The
Federal Reformulated Gasoline Program was established in the Clean Air Act of
1990 as a means to provide reductions in the emissions of air pollutants from
motor vehicles. The importance of
dealing with MTBE contamination is three-fold.
First, the fact that MTBE is highly water-soluble and absorbs less on
soils, relative to other components of gasoline means that following a spill or
leak it tends to migrate faster and further than other components of gasoline.
Secondly, while health risks due to MTBE water contamination are still
being investigated, contamination at low levels does cause taste and odor
problems thus rendering the water undrinkable.
And lastly, the number of studies demonstrating that water systems are
currently impacted by MTBE.
By
1998 MTBE had become the 4th highest organic chemical produced in the
United States. The impact of
contamination becomes clear when one looks at the situation in South Lake Tahoe,
California, which was forced to shut down more than half of its supply wells due
to impacts or imminent impacts to its wells and is facing cleanup costs
estimated around $50 million.
There
are also a growing number of studies that demonstrate the local and regional
scale of MTBE contamination. For
example, one USGS study looked at shallow monitoring wells in newly developed
areas of the Boston, Massachusetts metropolitan area which has sand and gravel
aquifers and found MTBE in 52% of the wells. Another USGS study evaluated the
occurrence and distribution of MTBE in drinking water in northeast and
Mid-Atlantic States that involved the collection of existing information from
20% of community water systems in the area.
MTBE was found in detectable quantities in 8.9% of the samples with 1%
exceeding 20ppb (the lower limit of EPA’s drinking water advisory).
The USGS, as part of the NAWQA (National Ambient Water Quality
Assessment) Program collected samples between August and November 2000 from 30
randomly selected drinking water supply wells screened in the unconfined aquifer
to assess occurrence and distribution of selected pesticides, volatile organic
compounds, major inorganic ions, and nutrients.
Volatile organic chemicals were present in all wells, generally at less
than 1 microgram/liter (roughly <1 ppb).
Chloroform, tetrachloroethene and MTBE were most frequently detected VOCs,
and were found in at least half of the samples.
17 of 30 samples had MTBE detected.
6 samples were between 1 and 10 ppb, 1 sample above the 10 ppb drinking
water standard.
Examples
of MTBE Contamination Across the U.S.
In
1998, a car accident in Maine resulted in a spill of less than 20 gallons of
gasoline, or less than 2 gallons of MTBE. The
incident resulted in the contamination of 24 domestic wells located within 2200
feet of the spill. Ten of the wells exceeded 100 ppb.
In response to this and several other incidents, the Governor of Maine
directed state health and environmental agencies to undertake a study of the
occurrence and concentrations of MTBE in Maine’s drinking water supplies by
sampling 1000 private wells and nearly all regulated public water supplies.
MTBE was detected in 16% of the private water supplies, with slightly
more than 1% exceeding the state drinking water standard of 35 ppb.
The questionnaire that accompanied the survey found that the wells were
not necessarily located near gasoline storage tanks or known gasoline spills.
MTBE was detected in 16% of the public water supplies tested, but no
samples exceeded the 35 ppb.
Pascoag,
Rhode Island is a village on northwest Rhode Island. Pascoag’s water supply came from a well field that served
about 4000 people. They had added
an additional well in the spring of 2001, and when first tested, the well
contained no MTBE. After initial testing MTBE levels began and signaled the
beginning of a five-month ordeal for the residents of the village.
On Labor Day weekend, a multiagency response began.
The release was traced to a gas station about 1700 feet from the well
field. In response to an
enforcement action by the state, an investigation was initiated, and limited
targeted remediation began.
By the end of October, concentrations had risen to about 1700 ppb. The
Rhode Island Department of Health issued advisories asking residents to limit
showering time, ventilate to reduce exposure to MTBE vapors, and reduce overall
water use to minimize the pumping of the wells, which was drawing MTBE to the
well field. By November, the
station operators had filed for bankruptcy.
In mid-November, carbon filters were installed on the water system, which
reduced contamination to between 40 and 100 ppb.
An adjoining town, Harrisville, that
had been planning a new well field has provided a long-term solution.
They accelerated installation of the new well field and after initial
disputes as to the administration of the two water districts; clean drinking
water began reaching residents on January 19th.
The investigation to determine the cause of release continues and
remediation in the source area is progressing.
The contamination of the Pascoag well field has been a very public issue
that seriously impacted all the people who live and work in Pascoag.
The
Greenbush area of Hyde Park, New York is another area impacted by MTBE
contamination. As of last August,
the neighborhood had 77 homes with carbon filters on wells, and at least 123
wells had been impacted. Three or four gas stations were identified sources of
the contamination. Contamination
was detected as much as 15 years ago at some of the sites.
The New York Department of Environmental Conservation will contribute
$1.9 million of the cost toward the town’s $3.1 million system to bring water
from Poughkeepsie.
Bucks
and Montgomery Counties, Pennsylvania, have also been dealing with MTBE
contamination of their water resources. A gasoline station in the town of Blue
reported a release in May 1998 two days after an explosion occurred at a nearby
building. The reported release of a
“few gallons,” turned out to be a leak of as much as 13,000 gallons, which
resulted in the explosion, and
evacuation of several families from their homes due to gasoline vapors.
Fourteen families have been connected to public water because their wells
were contaminated. A faulty leak detection device failed to alert the operator
about the release. Cleanup is
expected to cost $5 million, which will likely come from a state fund, since the
operator has no assets. .
In
New Hampshire, slightly over 16% of public water supplies have MTBE at 0.5 ppb
or higher. Of the private water supplies sampled, 27% had MTBE detected.
In
New Jersey, 15% of community water systems had detectable MTBE (>0.5 ppb), in
one area in the northern part of the state, up to 43% of the domestic wells had
detectable MTBE. MTBE has been
detected in 93% of private wells in Cranberry Lake area where gasoline-powered
boats are used, and the wells draw their water from the lake.
Beginning
in January 2001, the EPA Office of Drinking Water, as part of the Unregulated
Contaminant Monitoring Rule, now requires that public water supplies serving
more than 10,000 people include MTBE sampling.
This sampling is to collect information on occurrence of MTBE in drinking
water, to determine whether the problem is serious enough to warrant developing
a drinking water standard. They
also require sampling of a “representative number” of small systems (serving
<10,000 people) which is crucial in gaining a complete picture of MTBE
contamination. For example,
Delaware has 5 systems serving more than 10,000 people year-round, while
approximately 575 systems serve less than 10,000 people.
When the State of Delaware started testing for MTBE in June 2000, of the
210 samples collected in the first few months of testing, 38 samples or 18% had
detections of MTBE, two exceeded the 10 ppb Delaware MTBE drinking water
standard that became official on May 10, 2002.
Last
summer and early fall, the Delaware Department of Natural Resources and
Environmental Control and Public Health sampled public wells and surface water
intakes within a 1-mile radius of known hazardous waste sites in unconfined
aquifers. Delaware has over 400
public drinking water supply wells that are screened in unconfined parts of the
shallow aquifer alone. 39 wells and
4 surface water intakes were sampled, both raw and treated water, for a total of
58 samples. The samples were
analyzed for 69 regulated chemicals, 10 chemicals with secondary standards, and
108 other chemicals. Of the
58 samples, MTBE and chloroform were detected in 21 samples. MTBE was the only chemical that exceeded a Delaware or EPA
maximum contaminant level (MCL). These
included two wells with MTBE at 12 and 16 ppb, and one of those wells has more
recently increased to 30 ppb.
In
Delaware, as in most other states, domestic wells are normally only sampled for
MTBE near Leaking Underground Storage Tanks (LUST) sites, where potential for
impact is suspected. Approximately 60 domestic wells have been impacted, with
the earliest discovered in 1989, well before reformulated gasoline was used.
Wells screened as deep as 260 feet have had detects for MTBE, although
most wells impacted were shallower than 50 feet.
Two LUST sites have impacted 15-18 wells each.
When a well is impacted, the first response is normally carbon filters on
the well, monitoring, followed by deep replacement well, or extension of a
waterline. It costs from
$3000-$5000/well/year for filters, and $8-10,000 to drill deeper replacement
well. We recently extended a water
line approximately 1000 feet, due to two impacted wells that served 5
connections. The cost was $450,000.
Initially, a deeper well was drilled to replace one well, but the ground
water at 100 feet also contained MTBE.
As more studies on MTBE
contamination are being completed across the nation the extent of the problem is
becoming fairly well known. Further concerns are being raise by indications that
upgraded tanks that meet the 1998 standards are still leaking. Although there is
difficulty in separating problems with design and construction of underground
storage tank systems from operator errors or lack of training this issue still
needs to be addressed.
I commend the Subcommittee
for taking the time to evaluate and focus on the extent of MTBE contamination in
our nation’s water supplies. I
would be happy to respond to any questions you might have regarding my
testimony.
References
Occurrence and Distribution
of Methyl tert-Butyl Ether and Other Volatile Organic Compounds in the Northeast
and Mid-Atlantic Regions of the United States (1993-1998).
US Geological Survey Water Resources Investigation 00-4228.
Occurrence and Distribution
of Selected Contaminants in Public Drinking-Water Supplies in the Surficial
Aquifer in Delaware. USGS Open-File
Report 00-327.
Source Drinking Water for
Selected Public Drinking Water System: Report of Findings.
May 2002. Department of
Natural Resources and Environmental Control and Department of Health and Human
Services.
|
|
