Overview
Ground water monitoring
Vapor 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
More information

Groundwater Monitoring

NOTE: Ground-water monitoring cannot be used at sites where ground water is more than 20 feet below the surface.

Will I be in compliance?

When installed and operated according to manufacturer's instructions, a ground-water monitoring system meets the Federal leak detection requirements for new and existing UST's. Operation of a ground-water monitoring system at least once each month fulfills the requirements for the life of the tank. Ground-water monitoring can also be used to detect leaks in 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 ground-water monitoring or requirements that are different from those presented below.

How does it work?

Operation

Graphic of groundwater monitoring system Ground-water monitoring involves the use of one or more permanent monitoring wells placed close to the UST. The wells are checked at least monthly for the presence of product that has leaked from the UST and is floating on the ground-water surface. The two main components of a groundwater monitoring system are the monitoring well (typically a well of 2-4 inches in diameter) and the monitoring device.

Installation

The number of wells and their placement is very important. Many state and local agencies have developed regulations for this, usually requiring somewhere between one and four monitoring wells per UST (additional ones may be required for piping). Before installation, a site assessment is necessary to determine the soil type, ground-water depth and flow direction, and the general geology of the site.

Variations

What are the regulatory requirements?

Will it work at my site?

In general, ground-water monitoring works best at UST sites where:

A site assessment is critical for determining these site-specific conditions.

What other information do I need?

The proper design and construction of a monitoring well system is crucial to effective detection of leaked product and should be performed by an experienced contractor. Before construction begins, any specific State or local construction requirements should be identified.

Purchasing a ground-water monitoring system is similar to any other major purchase. You should "shop around," ask questions, get recommendations, and select a company that meets the needs of your UST site.

How much does it cost?

The capital costs for ground-water monitoring are generally much greater than the annual operating costs. The following cases illustrate the effect that different factors have on the cost of ground-water monitoring:

Case #1

One tank - well in backfill - short piping runs - manual monitoring - two wells installed:
Equipment Cost = $200-250
Installation Cost = $15-25/ft well depth
Annual Operating Cost = Under $100

Case #2

One tank - well not in backfill - long piping runs - automated monitoring - five wells installed:
Equipment Cost = $2,200-5,000
Installation Cost = $50-70/ft well depth; conduit to the central console = $500-2,000
Annual Operating Cost = Under $200