Asteroid Scientific

COMET: A Non-invasive, 24/7 Fuel Release Detection System

A synthesis of hardware and sophisticated software that provides release detection for very large bulk storage fuel tanks.

Monitoring real-time on a continuous 24-hour basis
A non-invasive tank approach
Multiple Leak Detectors
Trends for all dynamic information
Automatic System Alarm Notification (Visual & Aural)
Interfaces to existing ATG equipment

COMET components:

RTA - Release Trend Alert
BVA - Bulk Variance Alert
SCREENS
HDBA/HDA - Historical Data Analysis
STARS - Storage Tank And Release Simulator

Who can use this tool?

This system can be used by those who are involved with keeping their large bulk petroleum storage tanks (4,000,000 gallons or larger) in compliance for release detection to meet EPA and state regulations.
An automatic tank gauging system is acceptable by the EPA as a viable leak detection method for UST leak monitoring. Asteroid Scientific developed an advanced, sophisticated release detection system aimed at tightness testing of tanks larger than 4,000,000 gallons. The Asteroid Scientific COMET is a hybrid-based system capable of detecting leaks at the 0.2 to 0.5 gallons per hour rate on a monthly basis.

Background

   Since early 1991 Asteroid Scientific has been engaged in a research program involving large bulk storage tank release detection. This research has been focused on the unique UST’s at Red Hill Pearl Harbor, Hawaii. While the research was funded initially by DOD, funding was terminated at the end of 1994 and since then Asteroid Scientific has on its own initiative and at its own expense continued on to develop the end product of the original goal - COMET - a means of detecting leaks in the Red Hill fuel storage tanks.

   COMET is capable of monitoring on a continuous 24-hour basis all twenty (20) tanks at the Red Hill Fuel Facility for fuel leaks as small as 0.20 GPH with a 95% probability of detection and a 5% probability of false alarm. This COTS system is a true integrated, management system in that operator alerts, both visual and aural, are provided and the system can be operated in an unattended state.

   COMET is a non-invasive tank approach to leak detection - the tanks do not need to be opened and cleaned, a very expensive and time consuming process. COMET interfaces with existing ATG equipment as long as it provides a minimum level resolution of 1/64" (0.001') and a temperature resolution of 0.001 degrees F.

   Successful use or Proof-of-Concept of COMET has been demonstrated on three Red Hill tanks as of September 1998. On one tank that was static, COMET confirmed there was no release in progress. The second tank was found to be releasing fuel at a nominal 0.2 Gal/Hr rate. The third tank, where issues and receipts were involved during testing, COMET initially determined a nominal release rate of 1.5 Gal/Hr. After field adjustments were made to the input valving and piping the release rate changed to a nominal 0.5 Gal/Hr. These release detections were accomplished without pressure sensing and updated temperature sensors in the tanks.

The Red Hill Fuel Storage Facility is currently not protected. It does not have a release detection system nor a release detection program. At one time a release detection program was instituted under the acronym, Tank Integrity Management (TIM) program and under its aegis would have placed into operation a full-time release monitoring system versus its on-demand mode. Even though the Red Hill tanks lie over one of Oahu 's major potable water aquifers, serious pollution abatement is no longer a priority.
   COMET is readily adaptable to being integrated into the Red Hill tank farm Automated Fuel Handling System (AFHS).
   COMET can provide immediate compliance with state and Federal EPA requirements for a UST leak detection system for the Red Hill Fuel Storage Facility.

Technical

   Trends and logs of the pertinent field data as well as derived data (level, temperature, mass, net volume, and leak rate) are available for each tank being monitored.

Rather than a blind go-no-go result as provided by other systems (you do not want to make an official EPA notification if there really is not a tank leak because it really is a leaky valve), COMET provides in addition to the mentioned trend plots, various analysis tools for enhanced monitoring, for in-depth analysis as desired, and for tank environmental parameter studies in a confirmational mode or as a what-if analysis tool.
COMET is capable of communicating with any OPC server independent of the particular hardware device or I/O handled by the server. This allows the exchange of COMET data with OPC servers running on any computer in an enterprise-wide Ethernet TCP/IP based network.

FEATURES

Automatic System Alarm Notification (Visual & Aural)
Microsoft Windows 2000/XP Platform
An OPC client, based on COM/DCOM, connectivity with any OPC server
Internal TCP/IP Server
Interfaces to existing ATG equipment
Interfaces to AsterNet PIE-DAQ RH
Multiple Leak Detectors
Release Trend Alert™ (RTA)
Bulk Variance Alert™ (BVA)
3 Alert Condition Trend™ (ACT)
Trend Plot of NVOL Variance
Trend Plots of the 3 RTA Detectors
Trend Plots of the 3 ACT Indicators
Trend Plots of Tank Data (Level, Temperature, Pressure)
3 Release Trend Rate Detectors
3 Bulk Variance Rate Detectors
Fuel Facilities’ Format Inventory Report of Tank at Release Detection Time
Operator Interface Level Selection
Highly flexible for release detection rates
Dynamic Release Analysis
Historical Release Analysis
Release Alert Log File (RALF)

Multiple Leak Detectors with Trends

   COMET’s distinctiveness is due to a complex synthesis of hardware and sophisticated software. Level gauging equipment with a minimum resolution of 0.001 feet, special temperature arrays measuring temperature with a minimum resolution of 0.001 degrees Fahrenheit, and if possible, bottom pressure sensors with a sensitivity of 0.0092 psi coupled with a modern data scanning/logging system provide the necessary raw data for processing by a specially developed digital signal processing module. This data is then reduced and analyzed by a sophisticated software module that detects the leaks.

   Up to this point, other than possible basic detection principle differences, COMET would be no different than any other proposed leak detection system. COMET stands apart from all the others in what we believe will become an industry standard setting methodology - multiple leak detectors in one system with trends.
   COMET provides two basic types of release detectors at the operator level: RTA and BVA, Release Trend Alert and Bulk Variance Alert, with the RTA further broken down into prioritized pre-alerts.

   To begin with, reporting of a leak or spill to the Regulatory Authority does not start with the detection of a leak by COMET. COMET provides Alerts to the high statistical probability of a release, whether a low rate release by the RTA or whether a larger sudden release of a bulk quantity of fuel by the BVA and then the facility can begin its internal investigation of the potential leak.

RELEASE TREND ALERT (RTA) The Release Trend Alert (RTA) is segmented into prioritized Alert Condition Trends called ACT’s - ACT I, ACT II, and ACT III. An ACT I alert is the lowest level alert; it provides the earliest warning of a potential low rate release in progress. The ACT prioritization is created through a LIST of 3 leak detector time periods, i.e., Long, Intermediate, and Short Term. The appearance of an ACT I alert is not a full fledged Release Trend Alert signifying the highest confirmed, statistical probability of a release. A worst case scenario would be a false alarm with just an ACT I but in general it is the first alert of a deviation from standard operating norms. At this time the facility may elect to notify a trained analyst to research the COMET historical database for that tank and start a log watch for human scrutiny. When all three ACT’s are present, there is an official RTA, and COMET automatically provides to the operator a pop-up full size screen with a blinking Release Trend Alert and an audible buzzer requiring operator acknowledgment. Now it is time for the operator to definitely notify superiors of a potential release (unless this has been automated).	BULK VARIANCE ALERT (BVA) A Bulk Variance Alert (BVA) is determined by the net volume (NVOL) reaching or exceeding a minimum value of 5 barrels (210 gallons); it is completely independent of the states of the ACT alerts or a Release Trend Alert. The premise of the Release Trend Alert detector is to detect very low leak rates, although there is no upper limitation on the rate detection, and to provide a numerical value for that low leak rate in gallons per hour. By their very nature, very low leak rates require more diurnal time to statistically confirm a valid leak. If for some reason a large release occurs in a very short period of time, such as an impulse or step change in NVOL with no long term constant release rate, it is impossible to determine a true leak rate. Therefore some other detector is needed for this case - consequently the Bulk Variance Alert detector. For the case of large leak rates the BVA detector also has its LIST of projected release rate detectors called Long, Intermediate, and Short Term. COMET automatically provides to the operator a pop-up full size screen with a blinking Bulk Variance Alert and a different audible buzzer requiring operator acknowledgment.
OPERATOR SCREEN Built into COMET are various levels of personnel interface depending on expertise level. The basic system runs entirely in the background with no operator interface required, other than selecting which tanks are in static mode, i.e., not issuing or receiving fuel. The basic operator level, which requires no interface, provides a screen with 2 trend plots and 1 RTA release rate indicator panel. At the top of the screen the Net Volume Variance Trend provides a real-time graphical trend of the change (variance) in the net volume for the selected tank to monitor. Beneath it is a panel for the three RTA Release Trend Rates; they indicate the current calculation of the leak rate detectors, even if there is no leak. Color changes of the digital rate indicators are coordinated with the ACT signals to substantiate leak significance. At the bottom of the screen is the Alert Condition Trend that displays graphically the occurrence of the three ACT signals. To the right of the Alert Condition Trend, visual lamp indicators display whether a given ACT I, II, or III is currently ON. The operator screen is not something that has to be constantly monitored by the operator. Only the occurrence of either of the two basic leak detector alerts, RTA or BVA, or if an ACT I were to occur, would cause one to look at this screen to see what had been taking place. When the Release Detection Alarm Screen pop-ups, the operator will have to interface and respond to the audible alert as a minimum. Per the facility's tank integrity management program, the operator will then also have a designated response he is to make under such circumstances. As part of the total risk assessment analysis for a tank leak, any tank showing up as suspect should be physically checked out for any abnormal physical and operational conditions. A TIM Suspect Tank Inspection Form can be utilized for this process, see Form 2.2-3. The Release Analyst will be informed and he will conduct his investigations.	RELEASE ANALYST SCREEN For the release analyst there are 3 trend plots and 1 RTA release rate indicator panel. At the top of the screen there is still the Net Volume Variance Trend, but now it provides “real” or what COMET considers the “real” net volume variance in the fuel. The previous “operator” interface screen displayed the variance for the standard ASTM calculated net volume that is used in inventory logging - the “analyst” interface screen displays the ASM (Asteroid Scientific Method) calculated net volume variance which uses advanced mathematical techniques to “unmask” from the inherent system noise what is really transpiring with the thermodynamics of the fuel, temperature and pressure. In addition, 3 special LIST, filtered curves are superimposed on the Net Volume Variance curve to give a better approximation as to the general nature of the ongoing change in Net Volume Variance. Beneath the Net Volume Variance Trend is a new trend plot of the actual 3 RTA leak detectors. This is a key plot displaying the dynamic characteristics of the ongoing release. To the right of this trend is a panel with the current digital values of the three leak rate detectors. At the bottom of the screen is the same Alert Condition Trend as for the operator. It displays graphically the occurrence of the three ACT signals along with Alert Condition Trend visual lamps to the right. All trend curves and indicators (digital as well as visual) are color coordinated to facilitate understanding. A special feature of the COMET leak system is that the RTA and BVD rate indicators display in WHITE if the statistical analysis for their respective time windows do not indicate a statistically significant leak. Once the statistical parameters are met the indicators revert to their respective Alert color. Other enhancement aids for the analyst are three trend plots located off screen to the left (accessed by the scroll bar). These three trends are the three monitored field parameters: temperature, level, and pressure. These plots provide a visual history of what is happening in the tank with regard to these important tank environmental phenomena. Since the x-axis is the same for all trend plots and is time dependent and various graphical zoom, pan, and, cursor controls are made available, the analyst may make determinations as to when the leak actually started and/or when major changes occurred in the release rate. For example, if a release is detected on a given tank and it is determined that it is through the external valve/pipes, after the valve(s) is tightened the effect on the release rate can be charted and pinpointed on the Net Volume Variance Trend and the Release Rate Trend.
RELEASE DETECTION ALARM SCREEN The screen descriptions of the Real-Time Trends for the operator or the analyst are available per tank on a manually requested basis and thus can be displayed or not displayed as required. The Release Detection Alarm screen is the system pop-up screen that will automatically appear whenever an RTA or BVA alert condition occurs for any tank. This screen displays a lot of information for the state of the tank at the moment it went into alarm, eliminating any searching elsewhere for what was its condition at the time of alarm. The screen displays the date and time of the alert occurrence, a blinking indicator for the Tank No. and the type of alert (RTA or BVA), the leak rate detectors, the Net Volume Variance in barrels, the tank fuel level, its temperature, and its pressure. As an added feature it also provides an immediate display of a Release Inventory Record in the fuel facilities’ format showing the Opening Status (the inventory at the time the tank entered leak monitoring mode) and the Alert Status (the inventory at the time of the alert). A resulting Loss/Gain line item is also provided. And lastly of course there is an audible alert sounded at the same time as the appearance of this screen. An acknowledgment button is provided to silence the audible alarm and to stop the blinking of the Alert indicator. Another button provides access to the Real-Time Trends screen to see graphically the characteristics of this particular alert condition. The above information is also stored to a Release Alert Log File (RALF).	COMET-HDBA/HDA Historic Data Analysis Asteroid Scientific has been able to provide (on a requested basis) an interim solution for fuel facilities that do not have the on-line, real-time COMET system active on their ATG system, an off-line backup analysis of their historical data base to determine any tank's tightness compliance. The total COMET leak detection system provides the capability on a separate processor to process historical COMET information in pseudo real-time. The COMET-HDA (Historic Data Analyzer) allows fuel management on-site to view historic bulk storage tank leak detection data on a historic basis or a pseudo real-time basis, make adjustments to action alert sensor information settings, re-run post-data with new settings, formulate a position on the status of a tank (static, release, or ingress condition), and decide whether new configurations for the on-line, real-time detection sensors are required. Afterwards if the tank is still in “suspect” status then another NV3T on-site, on-line tool, TIM-HDBA, will be used by TIM personnel to analyze the suspect tank’s database (assuming the database is acceptable, if not it must be directly sent to an off-site facility for CRAM’ing and then analyzed using NV3T tool-TIM-HDA). If after on-site HDBA tool analysis the tank is still considered “suspect”, the collected data is sent to the off-site facility, the database is run though a more sophisticated off-line CRAM tool and the Analysis Operator then does a full HDA analysis. TIM-RH meets a performance standard of detecting a leak of 0.2 gallons per hour with a probability of detection of at least 95 percent and a probability of false alarm of no more than 5 percent. After an in-depth analysis by the Analysis Operator, there are only three possible bottom-line determinations for any TIM-RH tank tightness test: Pass, Fail, or Inconclusive. View historic bulk storage tank leak detection database information in pseudo real-time Evaluate post-site conditions and operational proceedings during and after a reported release/ingress alert
STARS Storage Tank And Release Simulator A Leak System Audit Compliance Tool This is a software add-on tool that provides what-if analyses for petroleum tanks. It can be used to confirm a supposed release state in a tank. Demo Allows modeling different tank environmental parameters such as level, temperature, and API over selected time periods to see the impact on the tank level A leak, ingress or egress, may be induced to occur at a specific time after start of test The leak rate and type are selectable - the resulting impact on the level trend is plotted over time Time stamped measurements are logged to a database that can be analyzed later by a leak detection program in an historical data fashion	RED HILL MOVIE (requires audio)

COMET: Very Large Bulk Tank Leak Detection

COMET: A Non-invasive, 24/7 Fuel Release Detection System