Ground water monitoring
Secondary containment with interstitial monitoring
Automatic tank gauging systems
Tank tightness testing and inventory control
Manual tank gauging
Leak detection for underground suction piping
Leak detection for pressurized underground piping
Statistical inventory reconciliation
Will I be in compliance?
When installed and operated according to manufacturer's instructions, vapor monitoring meets the Federal leak detection requirements for new and existing USTs. Operation of a vapor monitoring system at least once each month fulfills the requirements for the life of the tank. Vapor monitoring can also be installed to detect leaks from piping (see the later sections on leak detection for piping). You should find out if there are state or local limitations on the use of vapor monitoring or requirements that are different from those presented below.
How does it work?
Vapor monitoring measures "fumes" from leaked product in the soil around the tank to determine if the tank is leaking.
Vapor monitoring requires the installation of monitoring wells within the tank backfill. Usually one well per 20-40 feet surrounding tanks and piping is sufficient (the proper number depends upon the site conditions).
Calibration and Maintenance
All vapor monitoring devices should be calibrated annually to a gas standard to ensure that they are properly responding to vapor. Maintenance items vary depending upon the system, with manual systems usually requiring more maintenance than automated systems.
- Fully automated vapor monitoring systems have permanently installed equipment to continuously gather and analyze vapor samples and respond to a release with a visual or audible alarm.
- Manually operated vapor monitoring systems range from equipment that immediately analyzes a gathered vapor sample, to devices that gather a sample that must be sent to a laboratory for analysis. Monitoring results from manual systems are generally less accurate than those from automated systems. Manual systems must be used at least once a month to monitor a site.
What are the regulatory requirements?
- The UST backfill must be sand, gravel or another material that will allow the vapors to easily move to the monitor.
- The backfill should be clean enough that previous contamination does not interfere with the detection of a current leak.
- The substance stored in the UST must vaporize easily so that the vapor monitor can detect a release.
- High ground water, excessive rain, or other sources of moisture must not interfere with the operation of vapor monitoring for more than 30 consecutive days.
- Monitoring wells must be locked and clearly marked
Will it work at my site?
Before installing a vapor monitoring system, a site assessment should determine whether vapor monitoring is appropriate at the site. A site assessment usually includes at least a determination of the groundwater level, background contamination, stored product type, and soil type.
Some vapor monitoring systems can overcome site problems, such as clay backfill. You should discuss any problems that may apply to your site with the equipment salesman and your contractor to ensure they have considered the problems and will compensate for them, if necessary, when installing your vapor monitoring system.
What other information do I need?
Purchasing a vapor monitoring system is similar to any other major purchase. You should "shop around," ask questions, get recommendations, and select a method and a company that can meet the needs of your site.
How much does it cost?
The cost of a vapor monitoring system is influenced by the UST site condition, the required number of monitoring wells, their depth, whether an automated or manual system is chosen, the complexity of the chosen system, and its maintenance. If a site needs to be cleaned up before a system can be installed, costs would increase. However, vapor monitoring has very low annual operating costs (unless a manual system requires laboratory analysis). Here are two possible cases:
One tank - 20 feet of piping - manual monitoring using laboratory
analysis - two wells installed:
Equipment Cost = $200-400
Installation Cost = $1,000-2,000
Annual Operating Cost = $1,200
One tank - 70 feet of piping - automated monitoring and results - five
Equipment Cost = $2,800-3,000
Installation Cost = $2,000-4,000
Annual Operating Cost = under $25