N.Y. Comp. Codes R. & Regs. tit. 6, § 613-3.3 – Leak detection.

(1) Every facility must provide a method, or combination of methods, of leak detection that:
1. (i) can detect a leak from any portion of the UST and the piping that routinely contains petroleum;
2. (ii) is installed and calibrated in accordance with the manufacturer’s instructions; and
3. (iii) meets the requirements in subdivisions (c) and (d) of this section, as applicable.
(2) When a leak detection method operated in accordance with the requirements of subdivisions (c) and (d) of this section indicates that a leak may have occurred, the facility must notify the department in accordance with section 613-3.4(a) of this Subpart.
(3) Additional testing and inspection. When a leak is suspected, or where inspections or tests required by this Part have not been performed, the department may order the facility to inspect and to test the UST system or equipment for tightness and structural soundness. If the facility fails to conduct such inspections and tests within 10 days after receipt of the department’s order, the department may conduct inspections or tests for tightness. The expenses of conducting such tests as ordered by the department must be paid by the tank system owner.
(4) A facility that cannot implement a method of leak detection that complies with the requirements of this section must take the UST system out of service pursuant to section 613-3.5(a) of this Subpart.
(b) Specific requirements for category 1, 2, and 3 UST systems.
(1) Tanks. USTs must be monitored for leaks as follows:
1. (i) Every tank that is part of a category 1 UST system must be tested for tightness in accordance with paragraph (c)(1) of this section at yearly intervals, with the exception of the following:
  1. (a) any UST system storing no. 5 or no. 6 fuel oil;
  2. (b) any UST system that is monitored for leaks at weekly intervals using one of the methods listed in paragraphs (c)(2) through (5) of this section; or
  3. (c) any UST system having a tank that is encased in concrete that complies with paragraph (c)(6) of this section and is monitored at weekly intervals.
2. (ii) Every tank that is part of a category 2 UST system must be monitored for leaks using one of the methods listed in paragraphs (c)(2) through (5) of this section at weekly intervals. Continuous electronic monitoring satisfies the weekly monitoring requirement.
3. (iii) Every tank that is part of a category 3 UST system must be monitored for leaks in accordance with paragraph (c)(5) of this section at weekly intervals. Continuous electronic monitoring satisfies the weekly monitoring requirement.
4. (iv) All electronic tank monitoring systems must be inspected for operability at monthly intervals.
(2) Piping. Piping that routinely contains petroleum and is in contact with the ground must be monitored for leaks as follows:
1. (i) Pressurized piping.
  1. (a) Piping installed before December 27, 1986 that conveys petroleum under pressure must be tested for tightness in accordance with paragraph (d)(2) of this section at yearly intervals, with the exception of the following:
    1. (1) piping associated with any UST system storing no. 5 or no. 6 fuel oil;
    2. (2) any pressurized piping that is equipped with an automatic line leak detector that is operated in accordance with paragraph (d)(1) of this section.
  2. (b) Piping installed on or after December 27, 1986 that conveys petroleum under pressure and is part of a UST system storing motor fuel must be equipped with an automatic line leak detector that is operated in accordance with paragraph (d)(1) of this section.
2. (ii) Suction piping. Piping installed before December 27, 1986 that conveys petroleum under suction must be tested for tightness in accordance with paragraph (d)(2) of this section at yearly intervals, with the exception of piping associated with any UST system storing no. 5 or no. 6 fuel oil.
3. (iii) All electronic piping monitoring systems must be inspected for operability at monthly intervals.
  (c) Methods of leak detection for tanks.
  Each method of leak detection for USTs used to meet the requirements of paragraph (b)(1) of this section must be conducted in accordance with the following:
(1) Periodic tightness testing.
1. (i) Qualifications of test technicians. All tightness tests must be performed by a technician who has an understanding of variables which affect the test and is trained in the performance of the test.
2. (ii) Test reports.
  1. (a) A copy of the test report must be provided by the facility to the department within 30 days after performance of the test.
  2. (b) All test reports must be in a form satisfactory to the department and must include the following information:
    1. (1) facility registration number;
    2. (2) tank identification number used on the application form required in section 613-1.9 of this Part for the UST and piping tested;
    3. (3) date of test;
    4. (4) results of test;
    5. (5) test method;
    6. (6) certification by the technician that test complies with criteria for a tightness test in subparagraph (iii) of this paragraph;
    7. (7) statement of technician’s qualifications;
    8. (8) address of technician; and
    9. (9) signature of technician.
3. (iii) Tank tightness testing must be capable of detecting a leak at the rate of 0.1 gallon per hour from any portion of the UST that routinely contains petroleum while accounting for the effects of thermal expansion or contraction of the product, vapor pockets, tank deformation, evaporation or condensation, and the location of the water table.
(2) Automatic tank gauging. Equipment for automatic tank gauging which tests for the loss of petroleum must meet the following requirements:
1. (i) the automatic petroleum level monitor test can detect a leak at the rate of 0.2 gallon per hour from any portion of the UST that routinely contains petroleum; and
2. (ii) the test must be performed with the system operating in one of the following modes:
  1. (a) in-tank static testing conducted on a weekly basis; or
  2. (b) continuous in-tank leak detection operating on an uninterrupted basis or operating within a process that allows the system to gather incremental measurements to determine the leak status of the UST at weekly intervals.
(3) Vapor monitoring. Testing or monitoring for vapors within the soil gas of the excavation zone must meet the following requirements:
1. (i) the materials used as backfill are sufficiently porous (for example, gravel, sand, crushed rock) to readily allow diffusion of vapors from leaks into the excavation area;
2. (ii) the stored petroleum, or a tracer compound placed in the UST system, is sufficiently volatile (for example, gasoline) to result in a vapor level that is detectable by the monitoring devices located in the excavation zone in the event of a leak from the UST;
3. (iii) the measurement of vapors by the monitoring device is not rendered inoperative by the groundwater, rainfall, or soil moisture or other known interferences so that a leak could go undetected for more than seven days;
4. (iv) the level of background contamination in the excavation zone will not interfere with the method used to detect leaks from the UST;
5. (v) the vapor monitors are designed and operated to detect any significant increase in concentration above background of the petroleum stored in the UST system, a component or components of that substance, or a tracer compound placed in the UST system;
6. (vi) in the UST excavation zone, the site is assessed to ensure compliance with the requirements in subparagraphs (i) through (iv) of this paragraph and to establish the number and positioning of monitoring wells that will detect leaks within the excavation zone from any portion of the UST that routinely contains petroleum; and
7. (vii) monitoring wells are clearly marked and secured to avoid unauthorized access and tampering.
(4) Groundwater monitoring. Testing or monitoring for liquids on the groundwater must meet the following requirements:
1. (i) the petroleum stored is immiscible in water and has a specific gravity of less than one;
2. (ii) groundwater is never more than 20 feet from the ground surface and the hydraulic conductivity of the soil(s) between the UST system and the monitoring wells or devices is not less than 0.01 cm/sec (for example, the soil should consist of gravels, coarse to medium sands, coarse silts, or other permeable materials);
3. (iii) the slotted portion of the monitoring well casing must be designed to prevent migration of natural soils or filter pack into the well and to allow entry of petroleum on the water table into the well under both high and low groundwater conditions;
4. (iv) monitoring wells must be sealed from the ground surface to the top of the filter pack;
5. (v) monitoring wells or devices intercept the excavation zone or are as close to it as is technically feasible;
6. (vi) the continuous electronic monitoring devices or manual methods used can detect the presence of at least one-eighth of an inch of free product on top of the groundwater in the monitoring wells;
7. (vii) within and immediately below the UST system excavation zone, the site is assessed to ensure compliance with the requirements in subparagraphs (i) through (v) of this paragraph and to establish the number and positioning of monitoring wells or devices that will detect leaks from any portion of the UST that routinely contains petroleum; and
8. (viii) monitoring wells are clearly marked and secured to avoid unauthorized access and tampering.
(5) Interstitial monitoring. Interstitial monitoring between the UST system and a secondary barrier immediately around or beneath it may be used if the system is designed, constructed, and installed to detect a leak from any portion of the UST that routinely contains petroleum; and if the system meets one of the requirements set forth in subparagraphs (i) through (iii) of this paragraph:
1. (i) for a double-walled UST system, the sampling or testing method can detect a leak through the inner wall in any portion of the UST that routinely contains petroleum;
2. (ii) for a UST system with a secondary barrier within the excavation zone, the sampling or testing method used can detect a leak between the UST system and the secondary barrier, and the following conditions are met;
  1. (a) the secondary barrier around or beneath the UST system consists of artificially constructed material that is sufficiently thick and impermeable (at least 1×10^-6 cm/sec with respect to water) to direct a leak to the monitoring point and permit its detection;
  2. (b) the barrier is compatible with the petroleum stored so that a leak from the UST system will not cause a deterioration of the barrier allowing a leak to pass through undetected;
  3. (c) for a cathodically protected tank, the secondary barrier must be installed so that it does not interfere with the proper operation of the cathodic protection system;
  4. (d) the groundwater, soil moisture, or rainfall will not render the testing or sampling method used inoperative so that a leak could go undetected for more than seven days;
  5. (e) the site is assessed to ensure that the secondary barrier is always above the groundwater and not in a 25-year flood plain, unless the barrier and monitoring designs are for use under such conditions; and
  6. (f) monitoring wells are clearly marked and secured to avoid unauthorized access and tampering.
3. (iii) For a UST system using continuous vacuum, pressure, or liquid-filled methods of interstitial monitoring, the method must be capable of detecting a breach in both the inner and outer walls of the tank and/or piping.
(6) Weep holes. Holes in the base of a concrete form encasing a tank may be used to detect a leak from any portion of the tank. Holes in the concrete form must be directly visible to an observer.
(d) Methods of leak detection for piping.
Each method of leak detection for piping used to meet the requirements of paragraph (b)(2) of this section must be conducted in accordance with the following:
(1) Automatic line leak detectors. Methods which alert the operator to the presence of a leak by restricting or shutting off the flow of petroleum through piping or triggering an audible or visual alarm may be used only if they detect leaks of 3 gallons per hour at 10 pounds per square inch line pressure within one hour.
(2) Line tightness testing. A periodic test of piping may be conducted only if it can detect a leak at the rate of 0.1 gallon per hour at one and one-half times the operating pressure.
(e) Leak detection recordkeeping.
Every facility must maintain records demonstrating compliance with all applicable requirements of this section. These records must meet the following requirements:
(1) the results or records of any sampling, testing, or monitoring must be maintained for at least three years;
(2) the results of tank and line tightness testing must be retained until the next test is conducted;
(3) a copy of the results of tank and line tightness testing must be submitted to the department within 30 days after performance of the test(s); and
(4) written documentation of all calibration, maintenance, and repair of leak detection equipment permanently located on-site must be maintained for at least three years after the servicing work is completed. Any schedules of required calibration and maintenance provided by the leak detection equipment manufacturer must be retained for three years from the date of installation.

(a) Leak detection requirements for all UST systems.