N.Y. Comp. Codes R. & Regs. tit. 6, § 613-2.3 – 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 of subdivisions (c) and (d) of this section, as applicable. In addition, the methods listed in paragraphs (c)(2), (4), (8), (9), (d)(1), and (2) of this section must be capable of detecting the leak rate or quantity specified for that method in the corresponding section of the rule with a probability of detection of 95 percent and a probability of false alarm of 5 percent.
(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 613-2.4(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, or where accurate inventory monitoring records are not kept and reconciled as required under paragraph (c)(1) of this section, the department may order the facility to inspect and to test the UST system or equipment for tightness. 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 613-2.6(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 monitored for leaks at weekly intervals using one of the methods listed in paragraphs (c)(2) and (4) through (9) of this section. Continuous electronic monitoring satisfies the weekly monitoring requirement. Additionally, any UST system which stores any amount of motor fuel or kerosene that will be sold as part of a commercial transaction must meet the 10-day inventory monitoring requirements in paragraph (c)(1) of this section.
2. (ii) Every tank that is part of a category 2 or 3 UST system must be monitored for leaks at weekly intervals in accordance with paragraph (c)(7) of this section. Continuous electronic monitoring satisfies the weekly monitoring requirement. Additionally, any UST system which stores any amount of motor fuel or kerosene that will be sold as part of a commercial transaction must meet the 10-day inventory monitoring requirements in paragraph (c)(1) of this section.
3. (iii) All electronic tank monitoring systems must be inspected for operability at monthly intervals.
(2) Piping. Piping that routinely contains petroleum must be monitored for leaks as follows:
1. (i) Piping installed on or before October 11, 2015 must meet one of the following requirements:
  1. (a) Pressurized piping. Piping that conveys petroleum under pressure must:
    1. (1) be equipped with an automatic line leak detector that is operated in accordance with paragraph (d)(1) of this section; and
    2. (2) have an annual line tightness test conducted in accordance with paragraph (d)(2) of this section or have monitoring conducted at weekly intervals in accordance with paragraph (d)(3) of this section. Continuous electronic monitoring satisfies the weekly monitoring requirement.
  2. (b) Suction piping. Piping that conveys petroleum under suction must either have a line tightness test conducted at least every three years and in accordance with paragraph (d)(2) of this section, or use a monitoring method conducted at weekly intervals in accordance with paragraph (d)(3) of this section. Continuous electronic monitoring satisfies the weekly monitoring requirement. No leak detection is required for suction piping that is shown by the facility to be designed and constructed to meet the following standards:
    1. (1) the underground piping operates at less than atmospheric pressure;
    2. (2) the underground piping is sloped so that the contents of the pipe will drain back into the UST if the suction is released;
    3. (3) only one check valve is included in each suction line; and
    4. (4) the check valve is located directly below and as close as practicable to the suction pump.
2. (ii) Piping installed after October 11, 2015 must meet one of the following requirements:
  1. (a) Pressurized piping. Piping that conveys petroleum under pressure must be monitored for leaks at weekly intervals in accordance with paragraph (c)(7) of this section and be equipped with an automatic line leak detector in accordance with paragraph (d)(1) of this section. Continuous electronic monitoring satisfies the weekly monitoring requirement.
  2. (b) Suction piping. Piping that conveys petroleum under suction must be monitored for leaks at weekly intervals in accordance with paragraph (c)(7) of this section. Continuous electronic monitoring satisfies the weekly monitoring requirement. No leak detection is required for suction piping that meets subclauses (i)(b)(1) through (4) of this paragraph.
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) Inventory monitoring. Inventory monitoring must be conducted in the following manner:
1. (i) volume measurements for petroleum delivered, dispensed, and the amount still remaining in the UST (or each interconnected set of USTs), must be recorded each operating day;
2. (ii) the equipment used must be capable of measuring the level of petroleum over the full range of the tank’s height to the nearest one-eighth of an inch;
3. (iii) the petroleum delivered must be reconciled with delivery receipts by measurement of the volume before and after delivery;
4. (iv) deliveries must be made through a drop tube that extends to within one foot of the tank bottom;
5. (v) petroleum dispensing must be metered and recorded within an accuracy of six cubic inches for every five gallons of petroleum withdrawn;
6. (vi) the measurement of any water level in the bottom of the UST must be made to the nearest one-eighth of an inch and recorded each operating day; and
7. (vii) on a daily basis, the facility must calculate the difference between the expected and actual amount of petroleum in the UST. At 10-day intervals, the facility must calculate the sum of the daily differences and compare it to the thresholds in clauses (a) and (b) of this subparagraph to determine if a leak is suspected. A leak is suspected when:
  1. (a) the UST has a recurring accumulation of water within the 10-day period; or
  2. (b) the sum of the daily differences over the ten-day interval exceeds the largest of three-quarters of one percent (0.0075) of:
    1. (1) tank design capacity;
    2. (2) total amount of petroleum delivered to the UST system; or
    3. (3) total amount of petroleum dispensed from the UST system.

(2) Manual tank gauging. Manual tank gauging must meet the following requirements:

(i) tank petroleum level measurements are taken at the beginning and ending of a period, as set forth in subparagraph (iv) of this paragraph, during which no petroleum is added to or removed from the UST;
(ii) level measurements are based on an average of two consecutive stick readings at both the beginning and ending of the period;
(iii) the equipment used is capable of measuring the level of petroleum over the full range of the tank’s height to the nearest one-eighth of an inch;

(iv) a leak is suspected and subject to the requirements of section 613-2.4 of this Subpart if the variation between beginning and ending measurements exceeds the weekly or monthly standards in Table 2 of this subparagraph:

Table 2: Manual Tank Gauging
Design Capacity of UST	Minimum Duration of Test	Weekly Standard (One Test)	Monthly Standard (Four-Test Average)
550 gallons or less	36 hours	10 gallons	5 gallons
551-1,000 gallons (when tank diameter is 64")	44 hours	9 gallons	4 gallons
551-1,000 gallons (when tank diameter is 48")	58 hours	12 gallons	6 gallons

(v) USTs of 550 gallons or less design capacity and USTs with a design capacity of 551 to 1,000 gallons that meet the tank diameter criteria in Table 2 of this paragraph may use this as the sole method of release detection. USTs of greater than 1,000 gallons design capacity may not use this method to meet the requirements of this Subpart.

(3) Tank tightness testing. Tank tightness testing (or another test of equivalent performance) 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.
(4) 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.
(5) 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.
(6) 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.
(7) 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 for the petroleum stored) 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.
(8) Statistical inventory reconciliation. Statistically based testing or monitoring methods must meet the following requirements:
1. (i) report a quantitative result with a calculated leak rate;
2. (ii) be capable of detecting a leak rate of 0.2 gallon per hour; and
3. (iii) use a threshold that does not exceed one-half the minimum detectible leak rate.
(9) Other methods.
1. (i) Any other type of leak detection method, or combination of methods, can be used if it can detect a leak at the rate of 0.2 gallon per hour or a leak of 150 gallons within a month with a probability of detection of 95 percent and a probability of false alarm of 5 percent.
2. (ii) The department may approve another method if the owner and operator can demonstrate that the method can detect a leak as effectively as any of the methods allowed in paragraphs (4) through (8) of this subdivision.
  (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. The facility must conduct a test of the operation of the leak detector at yearly intervals.
(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.
(3) Alternative leak detection methods. Any of the methods in paragraphs (c)(5) through (8) of this section may be used if they are designed to detect a leak from any portion of the piping that routinely contains petroleum.
(e) Leak detection recordkeeping.
All facilities 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.