United States Environmental Protection Agency Hazardous Waste Engineering Research Laboratory Cincinnati, OH 45268 Research and Development EPA/600/S2-86/001 July 1986 v>EPA Project Summary Underground Tank Leak Detection Methods: A State-of-the-Art Review Shahzad Niaki and John A. Broscious The full report is a state-of-the-art review of available and developing methods for finding small leaks in underground storage tanks used pri- marily for gasoline and other liquid petroleum fuels. It describes (based on information provided by the manu- facturers or practitioners) a total of 36 volumetric, nonvolumetric, inven- tory monitoring, and leak effects mon- itoring detection methods; provides general engineering comments on each volumetric and nonvolumetric leak de- tection method; and discusses vari- ables which may affect the accuracy of detection methods. The emphasis throughout is on volumetric and non- volumetric leak detection methods. This Project Summary was devel- oped by EPA's Hazardous Waste Engi- neering Research Laboratory, Cincin- nati, OH, to announce key findings of the research project that is fully docu- mented in a separate report of the same title (see Project Report ordering infor- mation at back). Introduction Statement of the Problem In recent years, the increase in leaks from underground gasoline storage tanks has had a significant adverse environ- mental impact on the United States. Cur- rent estimates from governmental and industrial sources are that between 1.5 to 3.5 million underground storage tanks exist in the nation. Estimates of the num- ber of leaking tanks range from 75,000 to 100,000; and 350,000 others may develop leaks within the next five years. (Conference Report on H.R. 2867 Haz- ardous and Solid Waste Amendments of 1984, Congressional Record-House, H11140, October 3, 1984.) The 1983 National Petroleum News Factbook Issue forecasts the existence of approximately 140,000 gasoline service stations in the United States at the end of 1983. New York State estimates that 19 percent of its 83,000 active underground gasoline tanks are now leaking. Maine estimates that 25 percent of its 1,600 retail gaso- line underground tanks are leaking approximately 11 million gallons yearly. In Michigan 39 percent of groundwater contamination incidents are attributed to storage tanks. One of the primary causes of tank leakage is corrosion of the storage tanks. Product loss from leaking tanks may cause an adverse effect on the environ- ment, endanger lives, reduce income, and require the expenditure of millions of dollars for cleanup. To prevent or reduce the adverse effects of gasoline leakage, an accurate method must be used to determine whether or not an underground tank is leaking. The 1984 Resource Conservation and Recovery Act (RCRA) amendments regu- late underground storage tanks contain- ing petroleum products and substances defined in Comprehensive Environ- mental Response, Compensation, and Liability Act (CERCLA). RCRA regulations specify release detection, prevention, and corrections and require a leak detec- tion system, an inventory control system, and a tank testing (or equivalent) system. States are also passing legislation and writing regulations requiring both staged replacement of existing underground tanks and installation of monitoring wells to detect leaks. Performance standards for new tanks will be specified under ------- RCRA and included in various state regulations. Objective The objective of the full report is to identify existing and developing tech- niques to detect leaks in underground fuel storage tanks. This objective is ac- complished by a review of the manu- facturer's description of each method, its capabilities, and its,claimed precision and accuracy. The variables affecting leak detection methods are introduced in Section 5 of the report. This information should give the reader an understanding of the major variables and their effects on the ac- curacy of various leak detection methods. Section 6 presents a description of each detection method based on the available literature from the manufacturer or practitioner. The descriptions in Section 6 of the manufacturer's techniques for offsetting the effects on each detection method of these major variables are based on information from the manu- facturer's literature, reports, and/or verbal communications between the authors and the staff of the manufac- turer. This information was reviewed for correctness by most of the manufac- turers, practitioners, or developers of the detection methods (instruments). Independent engineering evaluations of error sources for each detection method are provided by the authors. Finally, Tables 1 through 9 in Section 2 sum- marize the capabilities of the leak detec- tion methods. Information in these tables is primarily from each manufacturer's description and, where noted, from the engineering comments in Section 6. Table 1 provides the phone number and contact name of the manufacturer/ practitioner for each manufactured leak detection method. Summary Existing and developing leakdetection methods were reviewed, and techniques for offsetting the effects of variables which affect accuracy were evaluated. In Tables 1 through 9 of the report, general information, general operational capabil- ities, and compensation for effects of variables discussed in this text are sum- marized for volumetric, nonvolumetric and other leak detection methods for underground storage tanks. Wherever it is appropriate, in these summary tables, the information furnished is based on engineering comments and not on the manufacturer's claim. Table 1. Leak Detection Methods. Leak Detection Testing Methods Manufacture or Practitioner Phone Numbers Phone Number Contact Name Volumetric (Quantitative) Leak Testing Methods 1. Ainlay Tank Tegrity Testing (TTT) 2. AftCO HTC Underground Tank Leak Detector 3. Certi-Tec Testing 4. "Ethyf Tank Sentry Testing 5. EZY-CHEK Leak Detector 6. Fluid-Static (Standpipe) Testing 7. Health Petro Tite Tank and Line Testing (Kent-Moore Testing) 8. Helium Differential Pressure Testing 9. Leak Lokator Test (Hunter Sunmark Leak Detection) 10. Mooney Tank Test Detector 11. "PACE Tank Tester 12. *PALD-2 Leak Detector 13. Pneumatic Testing 14. Tank Auditor 15. *Two-Tube Laser Interferometer System Nonvolumetric (Qualitative) Leak Testing Methods 1. 'Acoustical Monitoring System (AMS) 2. Leybold-Heraeus Helium Detector, Ultratest M2 3. Smith & Denison Helium Test 4. TRC Rapid Leak Detector for Underground Tanks and Pipes 5. 'Ultrasonic Leak Detector. Ultrasound 6. VacuTect (Tanknology) 7. Varian Leak Detector Inventory Monitoring 1. Gage Stick 2. MFP-414 Leak Detector (312) 328-6119 Mr. John Ainlay (312)333-3000 Mr. Gary L Everett (612)487-1484 (609) 452-8600 (517)684-7180 Mr. Jonathan Nedved Mr. A.V. Morschauser Mr. John Homer Method is used by different contractors (617)344-1400 (415)228-8400 (215)296-7380 (504)241-0453 (416)443-7032 (Not Available) 3425 W. 30th Ave. Vancouver, B.C., V6S1W3 CANADA Mr. Jack Stillwagon Mr. John Schweizer Mrs. Donna Hymes Mr. Joseph Mooney Mr. Jack Witherspoon Mr. Werner Grundmann Method is used by different contractors (617) 740-1717 Mr. William E. Baird (415) 424-1251 Mr. Joseph W. Maresca (615)966-4773 (412)327-5700 (415) 782-9788 (602) 623-0200 (914)592-1220 (403) 483-3506 (617)935-5185 Mr. Charles B. Oh Mr. Wm. C. Worthington Mr. Wm. H. Burkhart Mr. Glenn Thompson Mr. Mark A. Goodman Mr. Edward Adams Mr. Roger Schneider Method is used by different contractors (617) 238-6911 Mr. Stanley Hayes ------- Table 1. (continued) Leak Detection Testing Methods 3. TLS-150 Tank Level Sensor fVeeder-Root) Leak Effects Monitoring 1. Collection Sumps 2. Dye Method 3. Ground Water or Soil Core Sampling 4. Interstitial Monitoring in Double-Walled Tanks 5. LA.S.P. Monitoring System 6. Observation Wells 7. Pollulert and Leak-X Detection Systems 8. Remote Infrared Sensing 9. Surface Geophysical Methods 10. U-Tubes 11. Vapor Wells Phone Number Contact Name (203) 527-7201 Mr. Tony Spera Method is used by different contractors Method is used by different contractors Method is used by different contractors Method is used by different contractors (214)271-2561 Industrial System Marketing Method is used by different contractors (317)261-1130 (212)822-6767 Mrs. Joyce Rizzo (Pollulert) Mr. John Gelles (Leak-X) Method is used by different contractors Method is used by different contractors Method is used by different contractors Method is used by different contractors Recommendations The accuracy and precision of volu- metric leak detection methods (at least) should be determined in order to permit selection of the ones appropriate to any specific need. A cost-effective procedure is to make use of signal/noise theory and a high quality data base to estimate the likely performance of each method under a variety of representative conditions, and to verify performance by evaluating the method under a few selected, con- trolled conditions in a full-scale test apparatus. To conduct this survey, the American Petroleum Institute (API), and the Petro- leum Equipment Institute (PEI) were con- tacted for assistance in developing a comprehensive list of available detection methods. A limited patent search was performed to identify methods currently being developed, but not yet available commercially. In all, fifteen volumetric leak testing, seven non-volumetric leak testing, three inventory monitoring, and eleven leak effects monitoring methods were found. The information in the report is based almost entirely on information provided by the manufacturers and practitioners of the detection methods. Conclusions The conclusions listed below are based on the review of leak detection methods described in this report. 1. Variables affect the testing results of available or developing volu- metric, nonvolumetric, and in-tank monitoring methods used for leak detection of underground tank sys- tems. These variables are potential sources of errors in using the de- tection methods successfully. The importance of each variable may vary due to the characteristics of the tank being tested and to such test conditions as the temperature of additional product used to fill a tank prior to testing, depth of the water table, tank deformation, random variation of ambient tem- perature or pressure, tank inclina- tion, product vapor pressure, and tank age. 2. The 36 methods identified include 15 volumetric leak detection, 7 nonvolumetric leak detection, 3 in- tank monitoring, and 11 leak ef- fects monitoring methods. 3. Detection methods attempt to com- pensate for variables affecting accuracy in various ways. 4. Available data on the performance evaluation of the leak detection methods reviewed were not ade- quate to determine their relative accuracy. ------- Shahzad Niaki and John A. Broscious are with IT Corporation. Pittsburgh, PA 15235. John S. Far low is the EPA Project Officer (see below). The complete report, entitled "Underground Tank Leak Detection Methods: A State-of-the-Art Review,"(OrderNo. PS 86-737155/AS; Cost: $16.95, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, V'A 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Releases Control Branch Hazardous Waste Engineering Research Laboratory—Cincinnati U.S. Environmental Protection Agency Edison. NJ 08837 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Official Business Penalty for Private Use $300 EPA/600/S2-86/001 U 1329 PS ENV.RPROTECTIOH ACENCV CHICAGO ------- |