Using The Latest Innovation to Properly Monitor Containment Equipment
The latest monitoring method and technology available today is "Continuous Vacuum Monitoring”, commonly referred to by its acronym CVMS. The CVMS establishes a standard vacuum of 20" of water column, (equivalent to <2” of Hg, < 1psi), within the interstices to monitor the integrity of the primary and secondary containment barriers. By drawing a small vacuum on the interstitial space of tanks, sumps and product lines, the entire primary and secondary containment system is continuously monitored. Even the slightest loss of vacuum or the detection of liquid (hydrocarbon or water) will signify the possibility of a leak and put the system into an alarm condition. The system may also initiate positive Submersible Turbine Pump (STP) shutdown, as a result of a vacuum of liquid alarm condition, as required by local regulatory agencies.
This type of system is highly accurate and offers real-world advantages over other technologies. The system specifically addresses the inadequacies of hydrostatic or brine monitoring. For starters, vacuum and pressure monitoring systems do not maintain a head pressure within the interstitial space that is greater than operating conditions within the primary containment. Brine tanks, do maintain a higher head pressure and may weaken the containment. Further, because the CVMS replenishes itself with air, supplied via the STP (Submersible Turbine Pump) siphon port, the system automatically maintains the correct vacuum levels at all times to ensure accurate monitoring at all times. The system recharge point is faster than brine, and since there is no brine with this system a service call is no longer needed to refill lost brine.
A Continuous Vacuum Monitoring System typically consists of four main components:
Continuous vacuum monitoring is considered to be the best technology and solution available today to detect product loss and avoid environmental contamination due to leaks.
- Control Unit – housed inside the building and used to identify any alarm conditions. The system can monitor interstitial spaces separately or together depending on site-specific options. When properly installed the control panel is capable of shutting down the STP on an alarm condition caused by a breach in the monitored secondary containment area or can provide positive shutdown of an associated STP in conjunction with other monitoring systems, which includes but is not limited to, pressurized line leak detection and ISD control systems.
- Vacuum Lines – vacuum lines are attached to a sump unit and to the piping interstices with all product, vent, and vapor piping terminating into the turbine sumps for easy access. On certain configurations a “Vacuum Bridge” between the interstice of the piping located in separate sumps (i.e.: STP, Fill & Transition sumps) will be used, which will also terminate into the turbine sump.
- Sump Unit – the sump unit is mounted inside the tank sump and includes a liquid float switch, turbine siphon, and pressure switch and is the point where all vacuum input lines originate for connection to tank, sump and primary pipe interstices and penetration fittings.
- Vacuum Indicator Gauges – on certain systems, vacuum-monitoring gauges are used to pinpoint the precise location of leaks in the event of an alarm.
In fact, vacuum systems are so accurate and reliable that they are even used to assure the integrity of new tank secondary containment from the time of production to the time the tank is backfilled. Any significant loss of vacuum is an indication that the system requires further investigation before the product is put into use. In some cases the vacuum is left intact after installation as an ongoing means of leak detection monitoring.
The success of continuous vacuum monitoring in California is catching the attention of other states as it is now viewed as the most effective means of leak detection. Other states are likely to adopt this leak detection method. In fact, Florida is already considering following California’s lead of requiring continuous monitoring of secondary containment piping by vacuum, pressure or brine systems. In Florida, this is being driven by an increased emphasis on environmental protection against hydrocarbon discharges after more than 175 polyethylene piping incidents had occurred there over the past several years. Of these incidents, 12 percent resulted in hydrocarbon discharges into the environment. Although the majority of the leaks were contained in the piping interstice, the Florida Department of Environmental Protection states that more stringent monitoring is warranted.
Even without regulatory mandates, tank owners are increasingly concerned about protecting the environment and are deciding on the use of secondary containment monitoring because it offers substantial benefits. The environmental advantages of secondary containment monitoring would include the ability to provide additional insurance against product releases into the soil or groundwater. The financial and operational advantages would include simple and cost-effective leak-detection monitoring and an added level of protection against improperly installed or maintained tanks. From a financial standpoint it is a small expense to pay when compared to the potential costs that could be incurred from fines, cleanup, report writing, lawsuits and business interruption in the event of a release.
In the never-ending quest to protect our environment, continuous vacuum monitoring represents the latest innovation and technology to that end. Its ability to deliver a higher level of monitoring capability than ever before attainable will undoubtedly pay environmental dividends we can all appreciate.