2016 Tank Autopsy Report

2016 Tank Autopsy Report

By Mike Trombetta

Montana experienced 28 new confirmed petroleum storage tank (PST) releases in 2016, a significant drop from the previous year (37 confirmed in 2015). However, if you look at the nine-year trend in the graph below, this one-time reduction may not indicate a changing trend.




 The graph above depicts releases confirmed each year since 2006. The blue line shows releases from all PSTs, while the green line shows only releases from active systems. We still average about 30 new releases each year, 19 of which are from active tank systems. The 2016 count follows that trend; and if past history is a predictor of the future, we expect this trend to keep steady.  

The following discussion will focus on the 16 releases that occurred from active tank systems. We highlight active tank systems to identify the reasons releases happen, and assist owners and operators in preventing releases in the future.





While the number of releases caused by human error and sloppy operations are down from last year, they still make up the majority of releases – almost two-thirds of the releases are from active tanks. The six instances of sloppy operations are generally related to an accumulation of small spills and overfills at the tank fill port or around the dispensers. All six were confirmed when the active tank systems were taken out of service or an environmental assessment was conducted on the property. The sloppy operations were not identified or previously reported to DEQ until some other business need triggered the collection of a soil sample. These business “triggers” usually involve replacing or upgrading equipment, or transferring property.  As a general rule, the need to address a newly confirmed release during these other activities can be troublesome. The best way to prevent these situations is to avoid small spills and overfills, and when they do occur, clean them up before they soak into the soil.





The five releases caused by human error include two customers driving off with the nozzle still in their vehicles; one spilled 75 gallons of diesel and the other was about 200 gallons of diesel.  In another instance, a bus driver left his vehicle unattended and overflowed his tank. Approximately 20 gallons of diesel ran into a storm drain where the oil-water separator was already full, so it ended up flowing into surface water.

One release occurred when the fuel tank in a customer’s vehicle failed at a retail fueling facility. While this is not related to the storage tanks or  related equipment, it is noted as a reminder that customers and their vehicles are always a “wild card” that can cause releases and require the operator on-site to respond quickly.

Two fuel tankers spilled fuel when they overfilled tanks while delivering bulk fuel. One spilled approximately 500 gallons of diesel from an above-ground tank (AST), and the other overfilled an underground storage tank (UST) with approximately 1,600 gallons of jet fuel. In both cases the drivers only noticed the overfill when the fuel flowed out the vent lines.

The good news about the AST facility is that the tank was located within a concrete containment area, so the release was easily contained and cleaned up.  Nonetheless, there are some important lessons to be learned from this incident. DEQ’s records indicate that the first mistake was made by the facility operator, who mistakenly ordered fuel using total fuel volume already in the tank, rather than the available unfilled capacity of the tank (also called “ullage”). The second mistake was by the tanker operator, who apparently believed the order rather than gauging (“sticking”) the AST himself. This procedure is not in compliance with fire code that states, “The driver, operator, or attendant of a tank vehicle shall, before making delivery to a tank, determine the unfilled capacity of such tank by a suitable gauging device. To prevent overfilling, the driver, operator or attendant shall not deliver in excess of that amount” (2009, IFC).

The overfilling of the UST involved bad procedures and resulted in a serious spill that will be costly to cleanup and disruptive to business.  In this case, the tanker operator may have gauged the UST prior to offloading; however, the valves were mistakenly set to the wrong tank. When the UST’s 90% full alarm sounded, the driver turned it off. Again, he turned off the 95% alarm. Then when he turned off the 100% alarm, jet fuel was seen gushing out the vent pipe. In the six minutes it took to turn off the pump, approximately 1,600 gallons of fuel was released. Booms recovered about 32 gallons of fuel before the remainder soaked into the UST basin and then into the surrounding sandstone bedrock aquifer. Anecdotal recounts of this affair indicate the driver was immediately terminated from employment. This will be an expensive cleanup.

Three releases are related to equipment problems related to piping. One instance was caused by a leaky fitting where an above-ground tank was attached to a diesel pump at a center pivot irrigation system. Luckily, the farmer noticed the release flowing into the nearby creek and hired an environmental professional to deploy booms in the creek. A quick response to excavate approximately 300 cubic yards of contaminated soil allowed this release to be fully cleaned up and resolved in less than six months.



The other two equipment related releases are difficult to categorize other than just sloppy operations and poor installation. One release was found during an environmental site assessment as part of a land transfer. The total release was a sum of spills and overfills from four ASTs containing waste oil sitting behind a diesel maintenance shop and a poorly connected pipe to an underground oil-water separator. Information provided indicates the in-flow pipe to the oil-water separator was not sealed to the tank and released waste oil to the sub-surface soil whenever the tank was full. The poor installation (equipment problem) of the oil-water separator was a historical unregulated system, not uncommon, and seems to only be found during land transfers or when their release impacts other parties.

The other release was a poorly installed non-notified underground pipe not in compliance with Underground Storage Tank regulations and would not have been approved for installation if DEQ had been notified (as required). This installation was conducted illegally and may result in an enforcement action.  The leak occurred at a fitting where an underground copper line connects to an underground length of rubber tubing with hose clamps to allow for greater flexibility.

Approximately 100 feet of ½-inch diameter copper and rubber tubing for a heating system in a shop building was encased in a buried 2-inch diameter, schedule 40 PVC pipe and connected a concrete-vaulted AST system also used to fuel vehicles. The leak rate was measured to be 184 drips per minute (approximately 17.5 gallons per day). The red dyed diesel soaked into the subsurface and is a potential threat to groundwater and nearby domestic water wells. DEQ has required a full remedial investigation and more work is necessary to fully characterize the environmental impacts. Another interesting fact about this release is how it was discovered – It was found during the installation of a monitoring well to investigate an earlier petroleum release at the facility. One can only speculate how long it would have taken to identify this ongoing release if contaminated soil was not seen when drilling the boring.

One underground pipe connected to an AST corroded where it passed through an earthen berm at a terminal facility. The pipe was otherwise above-ground and only in contact with a short amount of soil, demonstrating the corrosive potential of iron pipes in contact with soil.

This wouldn’t be a complete autopsy list without reporting what products were lost. Below is a chart showing the products spilled in Montana from active tank systems in 2016 (includes two releases that contained two product types).




The best takeaway message from the 2016 tank autopsies is to be aware of all potential sources of sudden and historic releases so you can be proactive in preventing releases from occurring. And when releases do occur, report them to DEQ (and first responders when appropriate) immediately and get properly equipped and trained professionals on-scene as soon as possible. It is also important to report releases in a timely manner to avoid any loss of Petroleum Tank Release Cleanup Fund reimbursement or fines under Montana Rules (ARM 17.56.501-508).

Also, old historical releases seldom resolve themselves. Please identify and report these releases earlier rather than waiting to sell your facility. There are many funding sources that can help with cleanup; and if you address them now, you can have a much better land transfer experience.





Directors Office
Christine Mandiloff (Public Information Officer): 444-6469

Underground Storage Tanks
1520 East Sixth Avenue | P.O. Box 200901 | Helena, MT 59602-0901
Phone: 406-444-5300 | Fax: 406-444-1374
Email: dequstprogram@mt.gov  
UST Web: http://deq.mt.gov/land/ust
Leanne Hackney (Program Manager): 444-0485

Petroleum Tank Cleanup Section Federal Facilities and Brownfields
1225 Cedar Street | P.O. Box 200901 | Helena, MT 59601
Phone: 406-444-6444 | Fax: 406-444-6783
Remediation Web: http://deq.mt.gov/Land/rem
Aimee Reynolds (Bureau Chief): 444-6435
Amy Steinmetz (Section Supervisor): 444-6781

Petroleum Tank Release Compensation Board
1225 Cedar Street | P.O. Box 200901 | Helena, MT 59601
Phone: 406-444-9710 | Fax: 406-444-9711
PTRCB Web: http://deq.mt.gov/deqadmin/pet
Terry Wadsworth (Executive Director) 444-9712