Louisiana Administrative Code
Title 33 - ENVIRONMENTAL QUALITY
Part XI - Underground Storage Tanks
Chapter 7 - Methods of Release Detection and Release Reporting, Investigation, Confirmation, and Response
Section XI-701 - Methods of Release Detection

i. the automatic product level monitor test shall be capable of detecting a 0.2-gallon-per-hour leak rate from any portion of the tank that routinely contains product;

ii. the automatic tank gauging equipment shall meet the inventory control requirements of Subparagraphs 1.b and 1.f of this Subsection (or another test of equivalent performance); and

iii. the test shall be performed with the system operating in one of the following modes:

i. All RDDs shall have a 4-inch inside diameter and be constructed of either polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), or stainless steel, and shall be chemically compatible with the stored product. The screened interval shall be commercially fabricated, slotted, or continuously wound. Screen size shall be 0.01 inches. No solvents, glues, epoxies, thermal processes, or rivets shall be used.

ii. The screened interval shall extend from 1 foot beneath the ground surface through the entire excavation zone.

iii. Each RDD shall be sealed from the ground surface to a depth of 1 foot and provided with a locking cap. Each RDD shall be installed in such a fashion as to preclude the introduction of surface contaminants into the RDD.

iv. No RDD shall be installed within or penetrate native soils unless the hydraulic conductivity of the native soil is no less than 0.01 centimeters per second.

v. If only one UST system is located within the excavation zone, at least two RDDs shall be installed. For excavation zones containing between two and four UST systems, at least four RDDs shall be installed. If more than four UST systems are situated within a common excavation zone, additional RDDs shall be installed as appropriate to ensure adequate coverage for release detection. If, prior to the implementation of these regulations, fewer RDDs than required in this Clause were installed at a specific location, the owner or operator may request a variance by demonstrating to the satisfaction of the administrative authority that the excavation zone in question can be adequately monitored.

vi. A UST owner or operator may request a variance to the RDD construction requirements outlined above by demonstrating to the department that the proposed deviations will allow the excavation zone to be adequately monitored.

i. The materials used as backfill shall be sufficiently porous (e.g., gravel, sand, crushed rock) to readily allow diffusion of vapors from releases into the excavation area.

ii. The stored regulated substance, or a tracer compound placed in the tank system, shall be sufficiently volatile (e.g., gasoline) to result in a vapor level detectable by the monitoring devices located in the excavation zone in the event of a release from the tank.

iii. The measurement of vapors by the monitoring devices shall not be rendered inoperative by the groundwater, rainfall, or soil moisture, or other known interferences, so that a release could go undetected for more than 30 days.

iv. The level of background contamination in the excavation zone shall not interfere with the method used to detect releases from the tank.

v. The vapor monitors shall be designed and operated to detect any significant increase in concentration above background of the regulated substance stored in the tank system, a component or components of that substance, or a tracer compound placed in the tank system.

vi. In the UST excavation zone, the site shall be assessed to ensure compliance with the requirements in Clauses A.5.b.i-iv of this Section and to establish the number and positioning of monitoring wells that will detect releases within the excavation zone from any portion of the tank that routinely contains product.

vii. Monitoring wells shall be clearly marked and secured to avoid unauthorized access and tampering.

i. The regulated substance stored shall be immiscible in water and have a specific gravity of less than one.

ii. When an RDD is installed in the tank hold backfill, there shall be water present in the RDD during measurement at least once every 30 days in order to use liquid monitoring. When an RDD is installed in native soil, the distance to the water table shall never be more than 20 feet from the ground surface and shall be present in the RDD during measurement at least once every 30 days, and the hydraulic conductivity of the soil(s) between the UST system and the RDD shall not be less than 0.01 centimeters per second (e.g., the soil should consist of gravels, coarse-to-medium sands, coarse silts, or other permeable materials) in order to use liquid monitoring.

iii. The slotted portion of the RDD shall be designed to prevent migration of soils or the filter pack into the RDD and to allow entry of the regulated substance on the water table into the RDD under both high and low groundwater conditions.

iv. The continuous monitoring devices or manual methods used shall be capable of detecting the presence of at least 1/8 of an inch of free product on top of the water within the RDD.

v. Within and immediately below the excavation zone of the UST system, the site shall be assessed to ensure compliance with the requirements in Clauses A.5.c.i-iii of this Section and to establish the number and positioning of devices that will detect releases from any portion of the tank that routinely contains product.

vi. RDD shall be clearly marked and secured to avoid unauthorized access and tampering.

i. The secondary barrier around or beneath the UST system consists of artificially constructed material that is sufficiently thick and impermeable (at least 10-6 centimeters per second for the regulated substance stored) to direct a leak to the monitoring point and permit its detection.

ii. The barrier is compatible with the regulated substance stored so that a leak from the UST system will not cause deterioration of the barrier that would allow a release to pass through undetected.

iii. For cathodically protected tanks, the secondary barrier is installed so that it does not interfere with the proper operation of the cathodic protection system.

iv. The groundwater, soil moisture, or rainfall will not render the testing or sampling method used inoperative so that a release could go undetected for more than 30 days.

v. The site is assessed to ensure that the secondary barrier is always above the water table and not in a 25-year floodplain, unless the barrier and monitoring designs are for use under such conditions.

vi. Monitoring wells are clearly marked and secured to avoid unauthorized access and tampering.

i. report a quantitative result with a calculated leak rate;

ii. be capable of detecting a leak rate of 0.2 gallons per hour or a release of 150 gallons within 30 days; and

iii. use a threshold that does not exceed one-half the minimum detectable leak rate.