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RWM Home > Programs > Underground Oil Storage Tanks > UST Forms, Lists, Publications, Reports and Studies > Siting of New Underground Oil & Hazardous Substance Storage Facilities in Relation to Drinking Water Supplies & Significant Ground Water Resources

Siting of New Underground Oil & Hazardous Substance Storage Facilities in Relation to Drinking Water Supplies & Significant Ground Water Resources

Definition of Sensitive Geologic Area
Investigation Methodology
Preliminary Findings & Conclusions
Conclusions
Siting Regulations Summary Table

In follow-up to the recommendations of the Maine Task Force to Study the Improvement of Public Water Supply Protection and the intent of subsequent legislation (PL 1999, Chapter 761), as well as the Department’s overall responsibility for protecting ground water and thereby ensuring that Maine residents have now and in the future healthy drinking water, the Bureau of Remediation & Waste Management (BRWM) decided to review the status of one of the more historically significant sources of ground water contamination in Maine, underground storage tanks and facilities. The primary purpose of this evaluation was to determine whether new underground storage tank (UST) facilities, despite the 14 year prohibition of the installation of unprotected steel tanks and piping, still posed a risk of contamination of public and private drinking water supplies, the aquifers upon which they rely, their associated source waters (recharge areas), and the aquifers which will be the drinking water supplies of tomorrow for Maine cities and towns. For the purposes of this investigation, the scope was limited to the risk from oil and hazardous chemical pollution from spills and leaks to "sensitive geologic areas" since those areas have been well defined in Maine statute for the last 14 years. A secondary purpose of this investigation was to determine whether UST facilities located in sensitive geologic areas continue to contribute to the significant costs borne by the Maine Ground Water Oil Clean-up Fund for replacing oil contaminated drinking water supplies and remediating contaminated ground water

Definition of Sensitive Geologic Area: As defined in 38 M.R.S.A., Subsection 562-A, a sensitive geologic area includes:

  • Significant ground water aquifers ( significant sand & gravel aquifers as mapped by the Maine Geologic Survey and defined in current DEP regulations, Chap. 691);
  • Primary sand and gravel recharge areas;
  • Areas located within 1000’ of a public drinking water supply; and,
  • Areas located within 300’ of a private drinking water supply

Investigation Methodology: Bureau staff with help from Computer Services have undertaken since mid-May an investigation to collect data on new (installed since January 1, 1995) oil and hazardous substance UST facilities. Using the Maine Geographic Information System (GIS), the locations of new facilities were determined relative to significant sand and gravel aquifers and other sensitive geologic areas (close proximity to public and private drinking water supplies). Also investigated were the incidence of discharges at new facilities, how siting of other new groundwater threats are regulated in Maine, UST siting limitations in other New England states, and an evaluation of the economic benefits (i.e. avoided costs) of protecting groundwater as a drinking water supply resource. In addition to the efforts of Department geologists, engineers, and computer specialists, assistance and input was provided by the Maine Bureau of Health’s Drinking Water Program and the State Planning Office.

Preliminary Findings and Conclusions:

  1. The Task Force to Protect Public Water Supplies, established by the Maine Legislature in 1999, after reviewing the current state of public water supply protection in Maine, recommended in their January, 2000 final report: "There should be a higher degree of protection around source water areas, or areas that support public drinking waters." Follow-up legislation passed last session embraced this recommendation. The scope of this legislation, "An Act to Improve Public Water Supply Protection" (P.L. 1999, Chapter 761) is "to help ensure public health; to allow the State, municipalities and public water systems to identify significant public water supplies and strive for a higher degree of protection around source water areas or areas that are used as public drinking water supplies; and to allow the State, municipalities and water systems to pursue watershed or wellhead protection activities around significant public water supplies".
  2. In Maine, in 1990, 30 million gallons of gasoline flowed through 86 UST facilities, located within 1000’ of a public drinking water supply (as defined by Maine statute and the Federal Safe Drinking Water Act), according to MDEP Air Bureau survey data.
  3. During the time period of January 1, 1995 to August 14, 2000, 128 new underground storage tank (UST) motor fuel facilities have been registered and constructed in Maine; 55 or 43% were located in sensitive geologic areas. These newly constructed UST facilities, located in sensitive geologic areas, have a storage capacity of 871,600 gallons of gasoline and other motor fuels.
  4. Over the same time period 124 new heating oil UST facilities were registered, 19 of which (15%) were in sensitive geologic areas. Of these, approximately one-third (6) are marketing or distribution facilities (e.g. bulk plants) with a total storage capacity of 106,000 gallons.
  5. No new hazardous substance or chemical UST facilities were installed during the past 5 ½ years. The number of hazardous substance USTs has been declining steadily for more than 10 years. Of the seven (7) existing facilities, one (1) is located in a sensitive geologic area. This one facility stores underground 27,000 gallons of industrial chemicals in three tanks in a residential neighborhood.
  6. None of the new marketing and distribution heating oil facilities located in a sensitive geologic area have yet reported a spill or leak.
  7. Five (5) of the 55 UST motor fuel facilities located on sensitive geological sites reported having a spill or leak, often contaminating soil and groundwater (9%). The volume of gasoline or other product lost ranged from 1 gallon to over 6000 gallons (estimated volumes).
  8. Despite construction in Maine of new and replacement UST facilities since 1991 with secondary containment, and leak detection and overfill protection systems; operational errors, installation errors, other human errors and routine equipment failures due to wear and tear continue to result in discharges of gasoline and other petroleum products to the environment. A July, 2000 study funded by the Department provides some insight into this issue. Randomly selecting a 10% sample (262) of active oil UST facilities, this study found that 25% of facilities did not conduct the required annual operation and maintenance inspections. Of those which did, 29% found problems with equipment that was not functioning properly. The most common problems found were with overfill prevention equipment, spill buckets, tank leak detection probes, and in-line leak detection equipment for pressurized piping. When problems were discovered, they frequently (39% of the time) went uncorrected.
  9. The cost of investigating and remediating sensitive sites is generally greater than elsewhere in Maine. This is simply because at such sites humans are exposed or at significant risk of exposure to toxic chemicals which include known carcinogens (e.g. benzene) or suspected carcinogens (e.g. MTBE) via drinking water; as well as the remediation of Maine's future, most cost effective public drinking water supply sources - significant sand and gravel aquifers. The total clean-up cost of the five motor fuel discharges in sensitive geological areas to date is approximately $1.7 million and averages $339,300. The statewide 1995-1999 average cost for a leaking underground storage tank cleanup is approximately $42,000.
  10. In 1999, 89% of all sites (390) on the Department’s backlog of long-term oil remediation sites are located in sensitive geologic areas. One (1) percent of these petroleum remediation sites, account for $4.4 million or 40% of the Department's 1999 total oil remediation costs paid from the Maine Ground Water Oil Clean-up Fund.
  11. The economic benefits of encouraging siting away from drinking water resources may be in the millions of dollars range. They can be assessed by estimating the economic costs to the general public that, as a consequence of the increased protection of sensitive geologic areas, are avoided. In addition to avoiding cleanup costs of the magnitude described above, the economic benefits can be approximated by a number of other means.

    One method is to look at the 20 year cost to provide treatment to meet current drinking water health standards for typical small to moderately sized Maine community public water systems that utilize ground water as their sole source of drinking water, and in the event they were moderately contaminated (200 ppb) by one or a series of gasoline discharges at a nearby, new UST facility. For this purpose nine small to moderately sized Maine community public water systems were selected for study, ranging in size from 180 to 6600 people served. The present worth of the estimated capital and operating costs of treatment by GAC (granulated activated carbon) of these nine community water systems totaled $7,618,544, and range from $136,600 (Grand Isle) and $140,500 (Patten), to $1.7 million (Belfast) and $1.8 million (Houlton).

    A second method utilized to estimate the general magnitude of the potential financial benefits of not locating UST facilities in sensitive geologic areas is to look at the value of one type of sensitive geologic area, a significant sand and gravel aquifer currently used as a public drinking water supply source. Again the economic value of this proposal stems from preventing the aquifer from being polluted by petroleum from a catastrophic release or a series of smaller spills over time at a future UST facility located on the aquifer. The Augusta Water District is used here as a case study. This District’s supply wells are located in portions of the Belgrade esker, a high yielding sand and gravel aquifer. Based on actual pumping and yield data, this District obtains 800 million gallons annually of potable drinking water from this aquifer. At the current MPUC (Maine Public Utilities Commission) approved water rate of $2.89 per 100 cubic feet, the annual gross delivered value of this water, if not contaminated, is approximately $3.1 million. Deleting pumping, treatment and distribution costs, the value of the water alone, obtained from the aquifer, is estimated to be in the range of $800 thousand to $1.1 million per year.

    As demonstrated above, using different methods of calculation, the economic value of ground water as a drinking water source in Maine is clearly significant. Consequently, so are the benefits under this proposal by avoiding the costs of petroleum pollution. These projections are conservative and underestimate the value of Maine’s groundwater and drinking water. Because they fail to capture the full value of Maine’s ground water resources, the full measure of the benefits of this proposal are likewise underestimated. For example these estimates do not take into account the potential loss or impairment of currently untapped or underutilized high yield sand and gravel aquifers, the most cost effective water supplies of tomorrow for many Maine cities and towns fortunate enough to be located near such a resource. These aquifers should be considered an essential part of the State’s economic infrastructure.
  12. Utilizing the State’s GIS, sensitive geologic areas as defined above, would include approximately 13% of the State’s surface area. Making up this total area, 8% is within close proximity to private drinking water wells. Mapped high yielding sand and gravel aquifers, areas in close proximity to public water supply wells and their associated primary recharge (water source) areas make up the remaining 5%.
  13. The State and the Department currently have no jurisdiction to regulate the location and siting of petroleum or hazardous substance USTs with regard to the risk they pose to drinking water supplies or important ground water resources, except possibly in the unorganized townships by the LURC. Under the former Site Location of Development Law limited authority existed, however, it was lost in the revamping of that law.
  14. As shown in the attached table, the Department has to varying degrees some measure of regulatory authority over the siting of activities and facilities which pose a risk to ground water quality and drinking water supplies. The notable exceptions are underground and aboveground petroleum and hazardous substance storage facilities.
  15. With the assistance of the U.S. EPA's Office of Underground Storage Tanks in Region 1, the other New England states were canvassed to determine which, if any, regulated the siting of USTs. Except for Vermont and Maine, the other states have some type of siting standards in the form of prohibitions or setbacks for USTs relative to proximity to public drinking water supplies. New Hampshire also requires a setback from private drinking water supplies. Some of these are found in the state's UST regulatory program and others in their drinking water protection program. Rhode Island has prohibited the location of new motor fuel USTs in wellhead protection zones (source water protection areas) of community public water systems since 1993. Massachusetts not only prohibits new, but also replacement of existing USTs in the wellhead protection zone of a community public drinking water supply. Connecticut prohibits new USTs within 1/2 mile of a community public well and are promulgating regulations which would prohibit new USTs on significant aquifers, as determined by pump testing. New Hampshire requires new USTs to be more than 75' from the nearest private drinking water supply well.
  16. Over the past 16 years, the Bureau’s geologists and its hydrogeological consultants have documented that gasoline and its constituents travel great distances both in sand and gravel aquifers and in bedrock aquifers. Here are a number of examples. Benzene in a leaking underground storage tank (LUST) case in North Fryeburg has traveled more than 850’ at concentrations above drinking water standards. This site is in sand and gravel. In Buxton, benzene has traveled in bedrock approximately 2000’at concentrations above action levels. Similarly in Boothbay, benzene traveled 1400’. In Windham, MTBE traveled in solution with ground water more than 700 feet through bedrock and into a sand and gravel aquifer to reach a wellfield owned by the Portland Water District and used to provide drinking water to over 2,000 area residents. The problem will not go away with the reduction or possible future elimination of MTBE in gasoline stored and sold in Maine. At sites where only MTBE was found in water supplies, it was often only a matter of time before the more toxic BTEX (benzene, toluene, ethylene, & xylene) compounds, especially benzene would have shown up if the pollution source was not eliminated and cleaned up. Repeated small as well as larger discharges would eventually travel similar distances if unmitigated. Heating oil and kerosene contaminated ground water also travel distances sufficient to contaminate their share of wells, especially private wells. In bedrock, dissolved heating oil constituents frequently have been found to travel hundreds of feet at high concentrations.

Conclusion: The above findings provide an adequate basis to conclude that there is a sound, factual basis to propose that the siting and location of most new UST installations in sensitive geologic areas be limited. Despite their use of upgraded technology, the location and operation of new UST gasoline and other petroleum marketing and distribution facilities in close proximity to public drinking water supplies and our future public drinking water supply sources inherently place these ground water resources at serious risk from repeated discharges over a facility’s lifespan and will become an economic burden on the Maine Ground Water Oil Clean-up Fund and to the neighborhoods and communities in which they are located.