Compliance & Enforcement

The Compliance and Enforcement Section is responsible for ensuring that all UST owners install and operate UST systems in accordance with the applicable rules and regulations. Compliance is ensured through routine inspection of all active UST facilities and the prudent enforcement of any corrective action that may be determined during the course of these inspections. The focus of the regulations is to prevent any leaks from happening and when they do occur, to find them in a timely manner so as to mitigate the threat to human health and the environment posed by leaking UST systems.
The primary topics covered by the UST rules and regulations (11 Miss. Admin. Code Pt. 5, Ch. 2) with respect to the prevention and detection of leaks are:

• Corrosion Protection (§280.32, page 25)
• Tank Leak Detection (§280.43, page 38)
• Pressurized Piping Leak Detection (§280.44, page 42)
• Overfill Prevention (§280.30, page 22)
• Spill Prevention (§280.30, page 22)

Corrosion Protection

All metallic components of a UST system that routinely contain product and are in contact with the soil must have corrosion protection. Corrosion protection for metallic tanks and piping is accomplished by cathodic protection although tanks may have only an internal lining.

Corrosion Protection for Metallic Tanks and Piping

• Cathodic Protection – There are two types of corrosion protection (a) galvanic (sacrificial anode) or (b) impressed current. Both types of cathodic protection must be tested within 6 months of installation and once every three years thereafter. Click here for a form that may be utilized to document testing of galvanic cathodic protection systems. Click here for a form that may be utilized to document testing of impressed current cathodic protection systems. In addition to the three year testing requirement, impressed current systems must be inspected once every 60 days to ensure that the system is operating. Click here for a form that may be utilized to document 60 day checking of impressed current systems.
  Keep the results of the last two cathodic protection tests. For more information on cathodic protection, please refer to the booklet Guidelines For the Evaluation of Underground Storage Tank Cathodic Protection Systems.
• Internal Lining – If you have lined your tank, you must internally inspect the tank within 10 years of initial lining and every five years thereafter. Keep records of the lining installation and the inspection results.
• Internal Lining and Cathodic Protection – If you have lined tank and have cathodic protection, you don’t have to internally inspect the tank lining provided the cathodic protection system is properly maintained.
• Isolation – Metallic components may be protected by isolating them from contact with the soil/water.

Tank Leak Detection

Methods of leak detection for tanks include: a) monitoring wells; b) automatic tank gauging; c) inventory control; d) statistical inventory reconciliation; e) interstitial monitoring; or f) manual tank gauging. For more information on these methods of leak detection in Adobe Reader format click on Straight Talk on Tanks.

For tanks installed before October 1, 2008, choose one of the leak detection methods from the given options (a-f). For all tanks installed on or after October 1, 2008, you must conduct interstitial monitoring. Regardless of which method of tank leak detection you choose, ensure that you can document you have accomplished the required leak detection on a monthly basis.

Monitoring Wells for Tanks: Groundwater/ Vapor Monitoring

Monitoring wells are sometimes called observation wells and are shallow wells installed around the tanks for leak detection purposes. The well must be drilled one foot below the deepest tank and it must be constructed of factory-slotted well casing. You must visually check the groundwater that is within the wells once every thirty days with a suitable bailer. Lower the bailer into the well to allow water to half fill the bailer. If water is present in the well and a leak has occurred, petroleum product will float on top of the water in the bailer and will be clearly visible. Report 1/8″ or more of free product on the groundwater. If there is no water in the well, you must use a vapor meter capable of detecting the stored substance and properly calibrated according to the manufacturer’s instructions. Report a substantial change upward in the level of vapors.

Monitoring wells must be checked every 30 days and a written record maintained. Click here for a form that may be utilized to document monthly checks of monitoring wells.

Automatic Tank Gauge

An automatic tank gauging system (ATG) is comprised of a probe that is permanently installed in the tank and is wired to a monitor to provide information on product level. In order to provide the necessary tank leak detection, the ATG system must be programmed to perform a 0.2 gallon per hour (gph) leak test. You must ensure that you obtain at least one passing 0.2 gph leak test during each month the tank system is in operation. Automatic tank gauging systems that are utilized to meet the leak detection requirements must be inspected once every 12 months to ensure proper function. Click here for a form that may be utilized to document the inspection of automatic tank gauging equipment.

There are two ways an ATG can be set up to accomplish the required monthly 0.2 gph leak test:

• Using a “static test” where the tank must be taken out of service for three to six hours when no product can be withdrawn or added, or
• Using a “continuous test” where the ATG uses the “quiet” times when no on is dispensing fuel to accomplish the test.

Report to the Mississippi Department of Environmental Quality anytime you are unable to obtain a passing 0.2 gph leak test for any month. You must keep records showing a valid leak test was accomplished for each of the previous 12 months. To print out a booklet in Adobe Reader format on automatic tank gauging systems, click here.

Statistical Inventory Reconciliation

For statistical inventory reconciliation (SIR), a trained professional uses sophisticated computer software to conduct a statistical analysis of inventory, delivery, and dispensing data, which the owner must supply regularly. Report to the Mississippi Department of Environmental Quality anytime an inconclusive or fail is declared for any month.

To print out a booklet in Adobe Reader format about SIR, click here.

Secondary Containment with Interstitial Monitoring

This type of leak detection only applies to double-walled tanks. Interstitial monitoring can range from a visual inspection to see if a liquid is present, to continuous automated systems, such as those that electronically monitor for the presence of liquid product or vapors. Click here for a form that may be utilized to document electronic interstitial monitoring. If you are conducting electronic interstitial monitoring, the electronic devices that are installed within the interstice must be tested once every 12 months. Click here for a form that may be utilized to document testing of electronic interstitial monitoring devices.

If you do not have electronic monitoring, you must visually inspect the interstitial space at least every 30 days. Click here for a form that may be utilized to document visual interstitial monitoring. In addition, if you are conducting visual interstitial monitoring, you must inspect the secondary containment once every 12 months. Click here for a form that may be utilized to document secondary containment inspection. If the inspection indicates the secondary containment may not be liquid tight, you must conduct an integrity test to ensure the double-walled system is capable of preventing the release of product to the environment. Click here for a form that may be utilized to document integrity testing of the secondary containment.

Report to the Mississippi Department of Environmental Quality any time interstitial monitoring indicates that a leak may have occurred.

Manual Tank Gauging

Manual tank gauging can be used only for tanks of 2,000 gallons or less capacity. This method requires keeping the tank undisturbed (no deliveries or pumping gas) for at least 36 hours each week.
For detail information about manual tank gauging in Adobe Reader format, click here.

Pressurized Piping Leak Detection

All pressurized piping must have a method of leak detection that is capable of detecting small leaks (primary leak detection) and large leaks (catastrophic leak detection). Primary methods of piping leak detection are: a) monitoring wells; b) line tightness testing; c) interstitial monitoring; d) statistical inventory reconciliation; or e) 0.2 gph monthly leak testing. Catastrophic leak detection may be provided by either mechanical or electronic automatic line leak detectors.

For piping systems installed before October 1, 2008 choose one method of primary and one method of catastrophic leak detection method from the available options. For all pressurized piping systems installed on or after October 1, 2008 you must conduct interstitial monitoring as the primary method of leak detection and you must choose one method of catastrophic leak detection.

Monitoring Wells: Groundwater or Vapor Monitoring

The construction of monitoring wells for piping is the same as that for tanks. However for piping the wells must extended to a depth of one foot below the piping trench. One monitoring well must be placed for every 50 feet of piping. If all dispensers are within 50 feet of the tank bed monitoring wells, then no additional wells are needed for the piping.

Monitoring wells must be checked every 30 days and a written record maintained. Click here for a form that may be utilized to document monthly checks of monitoring wells.

Line Tightness Testing

For a line tightness test, the line is taken out of service and put under more pressure than the normal operating pressure. A drop in pressure over time, usually an hour or more, suggests a possible leak. If line tightness testing is your primary method of leak detection, you must have the test performed once every 12 months. Keep records of line tightness testing until the next record is performed. If a line fails a line tightness test, notify the Mississippi Department of Environmental Quality.

Secondary Containment with Interstitial Monitoring

The requirements for piping interstitial monitoring are the same as for tank interstitial monitoring.

Statistical Inventory Reconciliation for Piping

The requirements for piping statistical inventory reconciliation (SIR) are the same as for tank statistical inventory reconciliation.

0.2 gph Monthly Leak Testing

Many electronic automatic line leak detectors are capable of conducting 0.2 gallon per hour leak testing. If you have electronic automatic line leak detectors, ensure that they are properly programmed to perform the correct testing. In order to maintain compliance with the piping leak detection requirements, ensure that you obtain at least one passing 0.2 gph piping leak test for each month the tank system is in operation.

Automatic Line Leak Detectors

Compliance with the catastrophic piping leak detection requirements is accomplished by installing and properly maintaining automatic line leak detectors. Automatic line leak detectors may be mechanical or electronic. Whether mechanical or electronic, automatic line leak detectors must be able to detect a leak equivalent to 3 gallons per hour at 10 psi within 1 hour.

All automatic line leak detectors (both mechanical and electronic) must be tested once every 12 months to ensure proper functionality. Click here for a form that may be utilized to document testing of automatic line leak detectors.

Overfill Prevention

All tanks must be equipped with an overfill prevention device to prevent the tank from being overfilled. Overfill prevention may be accomplished by the installation and maintenance of one of the following: a) an automatic shutoff device; b) an electronic alarm; or c) a ball float valve.

Regardless of which type of overfill prevention device you have, it must be inspected once every 12 months to ensure that it is installed and functioning correctly. Click here for a form that may be utilized to document overfill prevention device inspection.

Automatic Shutoff Devices

Automatic shutoff devices are commonly referred to as a “flapper-valve”. These devices are installed within a drop tube that is inserted within the fill riser of the tank. When the product in the tank is 95% full, the flow of product from the tanker truck is shut off by the closing of the flapper valve. The connections between the tank fill riser and the delivery tank must be accomplished with “tight-fill” connections.

Overfill Alarms

Overfill alarms use probes installed in the tank designed to activate an alarm when the tank is either 90 percent full or within 1 minute of being overfilled. Either way, an alarm should provide the driver enough time to close the truck’s shutoff valve before an overfill occurs. The alarms should be located where the driver can see and hear them easily. Overfill alarms are often a part of the automatic tank gauge system.

Ball Float Valves

Ball float valves are placed at the bottom of the vent line several inches below the top of the UST. The ball floats on the product and rises with product level during delivery until it restricts vapor flowing out the vent line BEFORE the tank is full. If all tank fittings are tight, the ball float valve can create enough back pressure to restrict product flow into the tank. Ball float valves are not recommended with suction piping and pressurized delivery. The connections between the tank fill riser and the delivery tank must be accomplished with “tight-fill” connections.

Spill Prevention

All tanks must be equipped with spill prevention devices commonly referred to as spill buckets. Spill buckets are installed at the tank fill riser and are designed to catch any spill that may occur when the delivery truck’s hose is disconnected. Although these spills are usually small, repeated small releases can cause big problems. By using safe filling practices and catchment basins to contain spills, environmental problems can be mitigated. The tank fill riser must have a tight fill adaptor in order to make a leak proof connection with the hose of the delivery truck.

All spill buckets must be tested once every 12 months in order to ensure that they are liquid tight. Click here for a form that may be utilized to document spill bucket testing.