Table of Contents
- What is a UST Monitoring System?
- Why do Tank Owners need UST Monitoring Systems?
- How do Tank Monitoring Systems work?
- UST Leak Detection
- Sensor Types - Discriminating and Non-discriminating
- Leak Detection Recertification
- Automatic Tank Gauge (ATG) System Manufacturers
Veeder-Root TLS-350 Tank Monitoring System
What is a UST Monitoring System?
A UST monitoring system is a release detection system that tracks fuel levels within an underground or aboveground storage tank over a period of time to see if the tank is leaking. It will also provide measurements of the fuel level, volume and temperature, water level and volume and high and low fuel level warnings. Many systems are capable of monitoring double wall tanks and lines, pressurized piping and providing remote communication. UST monitoring systems are also referred to as fuel management systems, automatic tank gauge and leak detection systems.
Why do Tank Owners need UST Monitoring Systems?
Technician measuring the product level in tank manually
There are the three main reasons tank owners require a tank monitoring system:
- Regulatory Requirements
- Product Management
- Leak Detection
Automatic Tank Gauges (ATGs) are important to most tank owners because they help them meet state regulations which require tank and line tightness testing. ATGs also provide accurate product levels at a glance. With an ATG you won’t have to manually stick a tank to measure the tank volume. Knowing the tank volume will help provide accurate fuel inventories. Accurate fuel inventories make for easy reconciliation of product use or sales. Most importantly, they eliminate manual measurements and calculation of monthly inventory by providing detailed reports of product delivered and product dispensed.
How do Tank Monitoring Systems work?
ATG probe being installed in aboveground storage tank
ATGs use probes to monitor both fuel and water height. Most underground tanks will have some water at the bottom and regulations require that you maintain less than 1 inch of water in the tank at all times. Probes are accurate to 1/1000 of an inch for level measurements. These probes also measure temperature. Knowing the fuel temperature is important because fuel expands and contracts with temperature changes. The warmer the fuel, the larger the volume change. For example, a 1 degree Fahrenheit rise in a 10,000-gallon gasoline tank will increase the volume by 7 gallons.
The space between the inner and outer wall of a double wall tank is called the interstitial or annular space. A probe placed in a dry interstitial space checks for fluid that is either leaving the inner wall or entering from the outer wall. Some fiberglass underground tanks interstitial space is filled with brine or glycol and a probe is used to measure a drop in fluid level. A level drop would indicate that the interstitial fluid has either left the outer wall of the tank or mixed with the product in the inner wall. Either of these cases indicates a leak to the ATG connected to this probe.
Alternate terms for the space between the inner and outer wall of an underground tank:
- Annular space
- Interstitial space
- Secondary containment
Click above graphic for detailed view.
UST Leak Detection
Most underground fiberglass and steel tanks are cylindrical. ATG probes are installed around a rib of a fiberglass tank and set on the bottom of the rib. The ribs are interconnected via small air pockets so a leak on one end will migrate to the other end. Steel tanks typically utilize a float sensor located in a tube that connects to the bottom of the secondary containment. Any leaks in the secondary of a steel tank will trigger the sensor in the monitoring tube.
ATG’s are also used to monitor tank sumps, transition sumps and dispenser sumps. Continuous monitoring of the sumps insures that no fuel leaves the tank without being accounted for. Sensors are sometimes used in groundwater monitoring wells to check for fuel on water or for vapor monitoring.
These same sensors work for aboveground storage tanks to monitor for product level, water or loss of product.
Sensor Types - Discriminating and Non-discriminating
This interstitial sensor in submerged in oil which set off an alarm
A non-discriminating sensor is a float sensor that measures levels. No matter the type of liquid it is installed in, the sensor will indicate a level. These are useful for indicating a leak into an interstitial space, tank or dispenser sump. A discriminating sensor has poly carbon band on the outside of a set of floats. This poly carbon band expands when it comes in contact with fuel and increases resistance in the band. This increase in resistance in addition to the float sensor rising allows the ATG to tell the difference between fuel and water. Another type of discriminating sensor is the optical sensor. A beam of light is directed at a prism and if no liquid is present then the beam is returned to the sensor. If liquid is present on the outside of the prism the beam is then reflected away. This would be a non-discriminating sensor if not for the addition of continuity pins. Continuity pins added to the exterior of the prism allows the ATG to measure for the presence of fuel or water. If there is continuity between the pins then water is present and if there isn’t then fuel is present (water is conductive but fuel is not).
A look inside an intrinsically safe tank monitoring system
Each sensor is connected to the ATG through an intrinsically safe set of wires. These wires must be incapable of producing heat or spark that would ignite fuel vapors. Intrinsically safe devices are low voltage circuits which protect the sensor wiring from producing a short and igniting fuel in the tank or sumps. ATGs are constantly monitoring the sensors installed at the site. These systems are also capable of shutting down dispensers, reducing flow of in-tank pumps and notifying the owner/operator that a problem has been detected. Methods of notification include text, email, fax or external polling systems like a facility security alarm. ATGs are initially programmed by the tank service company to provide alerts at specific thresholds. Owners can specify a product level in inches or gallons that trigger a notification to a fuel delivery company. When the delivery is made the ATG measures the new level and provides a delivery report of inches and volume gained. In gasoline service stations, this volume is compared against sales at each pump, to reconcile the difference in the volume gained versus the fuel that was dispensed at the time of delivery.
ATGs are capable of monitoring levels and providing leak alarms but they also provide control of pumps. In the case of a generator where the fuel is supplied from a 110-gallon day tank or base tank, if the fuel level drops in the tank, the ATG can energize a transfer pump that will refill the day or base tank from a larger underground or aboveground tank.
Fuel dispensers have meters that measure the amount of fuel being pumped. ATG’s can indicate that a meter may be out of calibration if the inventory does not match the dispensed volume.
Oil Water Separator System
ATGs can be configured to monitor the oil level that accumulates in an oil water separator system (OWSS). The OWSS collects rainwater and separates out oil and other hydrocarbons before discharging clean water to storm drains. An ATG is used to notify the owner or waste management company to remove the accumulated oil when it reaches a certain thickness or depth in the tank.
Leak Detection Recertification
ATGs are capable of performing a static or statistical test that meets federal tank testing requirements. A static test is done when the tank is not accepting deliveries or dispensing product. The test monitors the tank for level changes over a 2-hour period. A statistical test is performed while the tank is still in service. It ignores the dispensing cycles and captures the levels in between those cycles to create enough data as captured in a static test.
- Monthly test - 50% capacity at .2 gallon/hour detected leak rate
- Yearly test - 90% capacity at .1 gallon/hour detected leak rate
In order to insure the ATG is capable of testing to the .1 gallon/hour rate the system needs to be calibrated and certified yearly to the manufacturer’s standard. The New Hampshire Department of Environmental Services developed this ATG test form to document the required annual testing of ATG equipment. Massachusetts does not provide a test form so CommTank technicians use a form created in-house to document the recertification procedure. The technician performing the test must be certified by the manufacturer and be trained in the performance of the test.
Example of a tank monitor inspection report:
ATG System Manufacturers
The following is a list of electronic monitoring system manufacturers whose equipment can be found in USTs and ASTs at facilities throughout New England.
"Far, far exceeded my expectations for what could have been a messy and smelly job."
"All at Comm Tank made a very stressful situation for us more than manageable. The men who came to do the work were always on time, extremely polite, and hardworking."
"In 34 minutes they achieved the removal without doing any cutting inside my home! Seeing is believing, which is why I sent you, today, the photos taken of their remarkable effort."
"Recently we hired your company Comm Tank to remove an underground oil storage tank buried in our front yard for many years. We also asked you to install a new aboveground oil storage tank next to our house."
William J. Lewis.
"They left the area cleaner than they found it. They were very friendly and fully explained how the tank was to be cut and removed."
"I would recommend Commtank to anyone who needs an oil tank removed. The price for such great service was very reasonable. Truly a good experience for me and my family."
"In the 40 years that I have lived in my house I have never had anyone do so much work, rip up so much sod yet leave everything in such a clean, neat and apparently undisturbed state."
"I want to thank you all for your excellent customer service and for going above and beyond the call of duty, to get my leaky oil tank problem resolved in time to sell my father's house."
"Paul’s recommendation along with the comfort level I felt dealing with your team made my decision to choose CommTank and easy one. Should I ever hear of anyone in need of a new oil tank I would recommend CommTank without hesitation."
"We have used CommTank now for inspections and service for the last two years. We have found the CommTank team nothing less than professional, knowledgeable and reliable."
"I do mean all of them…you could be proud of them and know that they represent your company in a very professional manner. In today’s world, you very rarely see this."
Billl and Barbara Clough.
"The project was on time, under budget, and everyone connected with the project was very easy to work with, both people on-site and in the office. "
Town of Southborough, Ma
"I want to thank you for the excellent work you and your crew have done at my station."
"I am emailing you with this word of “Thanks” to Comm Tank for one of the most professional companies I have used in quite sometime."
"When I called for an estimate, Margie was very informative and one of the reasons I chose CommTank to do the work."
Jack E. Meyer, M.D..
"I had an oil tank removed yesterday, and the whole operation could not have gone more smoothly."
"What could have been a stressful situation actually went smoothly without any issues or surprises. I would recommend CommTank in a heart beat to anyone in need of their services."
Scott E. Lechter.
"There were many steps throughout the process and at every step I was very well informed. The scheduling, coordination and communication was simply outstanding."
"I want to thank you for your work in the oil tank removal at my mother’s house in Walpole."
"Except for the oil smell for a while, you really couldn't tell that the work had been done; EVERYTHING was neat & tidy and cleaned up both inside and out."
"Thanks for your help and the customer service that CommTank provided."
North Reading, Ma
"Your employees did a nice job and were a credit to your company in their professional work and attitude."
"Thank you for doing a very nice job!"
Prides Crossing, MA
"Your crew just left my site and they are wonderful, clean, great, and nice!"
"I would certainly recommend your company."
"These two excellent employees came early, at 7:15 a.m. Which is very appreciated by us, clients that have to leave for our jobs."
"They patched the holes left from removing the fill and vent lines like pros - I did not expect this level of service."
"Kim and I are very happy to have found you!"
"We want to tank your for a job well done while removing the underground oil tank."
"I wanted to thank you for a great job on the installation of the new fuel dispenser."
"Thank you for your donation of 200+ gallons of fuel through your CommTank Cares Program to St. Clement Parish Schools. Your generosity is certainly a help to our schools and parish."
Reverend Paulo Cumin.
"just want to express my appreciation for the excellent service that was provide to me in the removing of our 1,000 gallon underground oil tank."
"What I think I’ll never forget was how clean the basement was after the two men had removed the contaminated soil from our house. It had never looked like that!"
"Early this month your company removed my almost 40-year-old tank from my basement and installed a Roth Tank. I was extremely pleased with the results and with the crew that did the work."
"It was neat and clean and they left the area spotless. The gentleman who came back to inspect the job was kind and courteous."
"The City is extremely grateful to CommTank for its assistance in this cleanup. We believe we made a very wise choice in the selection of CommTank. Please feel free to use me as a reference for your team's pursuit of other environmental work."
Thomas G. Ambrosino.
"She called to brag about how professional the service was, and how clean and precise the installation was."
"We really appreciate the responsiveness to what was a worrying situation and the two men who performed the work were true professionals."
"This company is the best. The price was very reasonable, better than anyone else I contacted, about $300.00 less,"
"I had my oil tank and boiler removed from my home. Comm Tank showed up on time and finished the job quickly and neatly."
"I want to thank CommTank for the wonderful job that your crew did yesterday while removing and installing my oil tank."
"Thanks so much for getting your guys out here so quickly to take care of the issue. While they could not tell exactly what caused the seepage, they ended up replacing the red connector with the fill gauge to be safe."
"There were two crews on separate days that did a great job and were very knowledgeable about their job and company."
"As for me the customer, I am very pleased on the workmanship that was performed, and I would recommend ComTank to anyone that needs a new tank."
"Your workers were out at my house in Wayland last week and did a fantastic job removing the oil tank from my basement."
"The quality of their craftsmanship is buzzworthy, the work surpassed my expectations."
"They showed up on time, were extraordinarily efficient and neat, provided a comprehensive removal, and were very courteous in all our dealings."
John P Senko.
"You and your entire on-site crew, including Santiago and Carlos, all have been first-rate and first-class."
"Thank you for your competence and professionalism, your cheerful and hard-working staff, your expertise with regulations/compliance issues, and for referring us to Tommasino & Tommasino in Boston."
Richard and Kristen Henshaw.
"Please note that this appreciation comes from a person managing construction for clients for some forty years."
"Excellent work so far. We wish these guys were on all three Boston projects."
Peachtree Corners, GA
"He will refer us to anyone and will definitely be using our services again."
"Please let the crew know that I really appreciate the hard work and professionalism."
"I spoke to Cindy the other day and reiterated to her about how happy we were with our experience."
"The thorough explanation of what was to be done was excellent."
"During this past summer I had an underground oil tank removed and replaced with an indoor Roth oil tank, and was exceptionally pleased with the service."
"In my opinion they were very professional and courteous."
Mary Louise Thrower.
"Thanks again to you and your team for the high level of workmanship and customer performance you provided."
"Your company has been most professional, timely, and informative!"
"This was our first experience with your company and we were very pleased from start to finish."
"Your crew were great to work with and did a great job, although very hot out there, they continued on with no complaints."
"All of our clients are more than satisfied with the quality of CommTanks installations and LEO is as well."
"It was a pleasure having them work at my house."
"They quickly went to work and solved the problem. As worried as I was, Luis made me feel that everything was going to be ok. Luis was always there no matter how many times I called."
Jeffery J. Graham.
New Bedford, MA
"We were so pleased with the removal of the old furnace."
"They tore down part of a wall, shoveled, removed my old tank and replaced it with a new tank, also gave me some oil."
"They were courteous and professional, timely and completed everything as well as anyone could have asked."
"I have dealt with contractors before and was very impressed with your crew."
"I would hope I would never have to have a UST removed again, but if I did, you would be the first people I would call."
"They left the basement much cleaner than when they started the job."
"Kevin's response and his team’s effort to help contain and cleanup a small spill were some of the best I have seen in my 40+ years in the petroleum industry."
"The technicians were outstanding. We needed 3 tanks removed from our basement."
"Kevin Hoag and Nelson were outstanding, they showed at 8:00 AM sharp, they were very professional, explaining all steps, very polite, their work was perfect."
"CommTank just finished the UST removal job and the customer is absolutely delighted."
"Amazed that this level of customer service still exists in this day and age!!"
Jamaica Plain, Ma
"Great job, completed on time, very aware of the Safety of our tenants."
Deborah M. McClory.
"Came when they said and did what they said quicker than I thought and left the cellar clean all at a reasonable price."
"I also commend Luis Diaz on his pleasant, informative phone manner when we first spoke and at the time of the site exploration. His handing of the situation convinced me to go with CommTank."
Newton Centre, Ma
"The professionalism and courtesy with which you and your crew handled this situation far exceeded my expectations and that of my customer."
"I will recommend your company to my colleagues and clients."
"From the moment I contacted Comm Tank, it was nothing but a positive experience."