Tank trouble

By Pia K. Hansen





The aquifer has always been a tricky concept. A vast lake just below the ground we walk on, it provides storage for one of the nation's most plentiful fresh water supplies. But people didn't really even know it existed until a public education program in the 1970s introduced it -- and the need to protect it -- to the residents who relied upon it.


A refresher course on the importance of the invisible aquifer came last fall when the Burlington Northern Santa Fe Railroad wanted to build a refueling depot with 500,000 gallons of fuel storage over the aquifer. The ensuing debate, which ultimately resulted in the depot being permitted by the Kootenai County Board of Commissioners for Rathdrum, Idaho, revived the public interest in the importance of protecting the aquifer, which is at risk for being so close to the surface. That debate also spurred some public officials in Spokane County to look into other threats to the aquifer; what they found makes the threat from the BNSF depot seem like a drop in the bucket.


Some estimates place the amount of gasoline and other petroleum products now being stored over the aquifer at 60 million gallons at any given time. And while the BNSF depot is required to have the most up-to-date containment and spill-prevention technology incorporated into its design, many of the storage tanks in Spokane County have no built-in protections and are only inspected every 10 years. Some of the tanks were built in the late-1940s.


Stan Miller, aquifer protection program manager for Spokane County, says that the problem with petroleum storage tanks is much larger and more complex than the debate about BNSF's refueling depot let on. "Compared to most of the tanks we already have around here, the tanks BNSF proposed were really tiny," says Miller. "What BNSF was talking about, relative to total amount petroleum product we already have stored on top of or close to the aquifer, is not a very large amount."


Many of the existing larger tanks (which hold 10,000 gallons or more -- some hold as much as a million gallons) have no liners underneath them and they have no other containment features than gravel berms to keep spills from migrating into creeks. At least one tank is built in an area where a naturally occurring subterranean clay layer would hopefully protect the aquifer. Others, however, like the Tosco tank farm by N. Market Street, sit on carefully monitored Superfund sites polluted by dozens of spills over the years.


Now Spokane County is looking to update its ordinances governing the maintenance of such storage tanks; the first public hearings on the issue are expected to be held in September or October.





Under current state and county regulations, the tank farm owners and operators inspect their own tanks and pipes on a regular basis, but some of the inspection practices are less than effective.


"In some cases, the control system is 'Gee there's oil on the ground,' " says Miller, "or they'll notice the level of oil or gas dropping in the tank."


This is exactly what happened two weeks ago near Pasco, Wash., when a pipeline running under U.S. Highway 12 began leaking. The leak in the pipeline was discovered on July 21 when the volume of petroleum being moved from one tank farm to another came up short, according to the state Department of Ecology. Since the pipeline, which is operated by Tidewater Barge Lines of Vancouver, had no electronic detection system, the company decided to crank up the pressure in the pipe hoping the gasoline would rise to the surface of the ground above the leak and help to locate the hole. Apparently all the petroleum that was leaking out at the same time was not as big a concern as finding the leak.


"This is not an appropriate method to locate a suspected leak on a pipeline," says Linda Pilkey-Jarvis of Ecology's spill response program. "There was a serious potential for a much more dangerous outcome. We are grateful that didn't happen."


The quarter-inch hole could have allowed as much as 16,000 gallons of petroleum to leak into the ground during the three different transfers where the shipments came up short.


While such an occurrence offers a reminder of the risks associated with storing and moving petroleum products, it's usually the bottoms of the tanks that cause problems when they begin leaking because of corrosion or cracks. And Pasco isn't sitting on an aquifer; an undetected leak in the Spokane area could have horrendous consequences.


"There is a tremendous risk; the tanks don't come up for inspection until 10-year intervals. Some are really old, from the '50s, and their failure point is usually the bottom," says John Roskelley, Spokane County Commissioner and instigator of the current review of the county's storage tank ordinance. "One big spill and people all around here would be drinking gasoline."





Petroleum product storage tanks have been part of the local landscape ever since the combustion engine hit the market. En route from the oil wells and the supertankers to the local gas stations, storing and handling the lifeblood of our fossil fuel-driven economy has always been a risky affair. Not only is there the constant worry of explosive fires and highly poisonous fumes, but gasoline has to be stored in many different containers before it ends up in our gas tanks. A large system of pipelines, with storage tank farms at either end, transports most of the gasoline to its end market. Once it reaches the local area where it will be sold, its final resting point is in a storage tank, which is usually part of a larger tank farm complex.


Many of the tanks in Spokane County were built in the 1950s, before the full extent of petroleum hydrocarbons' damaging effects on the environment were understood. During the '70s and the '80s, when the environmental movement began calling attention to the problems stemming from oil spills from tankers on the ocean and gasoline spills from trucks and tanks on solid ground, tank farm owners were more concerned about fire danger. Such worries led to the positioning of many tank farms outside of what was then the city limits -- in the Valley and on the North Side -- which, in Spokane's case, also located them right on top of the aquifer.


The old tanks usually have single-layer steel walls and bottoms. They are equipped with different systems of valves to regulate pressure inside the tank (so it doesn't blow up when it gets really hot outside) and to stop overflow during filling and emptying procedures.


Many pipes, leading from tank to tank or from tank to the truck filling stations, are above ground and thus readily available for visual inspection. Some pipes, like the ones in the Pasco incident, are below ground and they may have no leak detection system whatsoever. If they leak, the tank owners find out because some of the gas disappears on its way from tank to tank, or the level in one of the tanks is dropping. The pipes need to be dug up and pressure tested with something other than petroleum in order to locate a leak. To check the bottom of a tank, it needs to be emptied, cleaned out and inspected visually from the inside.


Most of the old tanks don't have liners underneath them, as is required of new tanks like those at the BNSF depot. The old ones usually sit on a bed of gravel that has been pushed up into a berm surrounding the entire tank farm area. The berms are there to keep the petroleum product from running into nearby creeks or rivers, but they will not keep a leak from reaching the groundwater.


"Right now, the protection we have is just sand and gravel berms. If we experienced catastrophic overflow, the gasoline and petroleum products would go straight to the aquifer," says Roskelley. "Some of the newer tanks do feature double bottoms, consisting of two separate steel layers with a monitoring system between them. It's usually the bottom that's the problem, and that can be a difficult area to monitor, but the double bottoms work well."





Roskelley is leading the review of the tank ordinance, which is expected to change the requirements for both existing and new tanks. It will culminate in a new county ordinance aimed at better protecting the aquifer in case of a large spill.


"Our tank regulations were pretty ancient, and that's what really worried us when BNSF started looking for a new location to build," he says. "There have been minor upgrades during the years, but nothing significant has changed for a long time. I want to make it clear, though, that this is not an investigation of the tank farms; this is a review of our ordinance."


Local tank farms are situated mainly on North Market Street and around Yardley in the Valley.


"The ones in the Valley are right dead center over the aquifer. And since we know of every tank there is, we know there could be up to 60 million gallons of toxic [substance] over the aquifer at any one time," says Roskelley. "We can never say how much there is for sure, because the tanks are not all full at the same time. The ultimate solution would be to move them all off the aquifer, but that's just not a possibility."


The biggest problem is that no tank farm has exactly the same construction as the farm next door, so in order for the ordinance to be effective, the county is going to have to find a way of addressing all safety issues for all tanks in one set of rules.


"My main concern is with the larger tanks," says Miller. "In 1986, the county and city adopted some regulations that required secondary containment for 11 new tanks. There have been 10 new 20,000-gallon tanks installed since then, and they have some protection around them. But in reality, since we passed the ordinance, only one large tank [larger than 100,000 gallons] has been installed." That means the other large tanks currently in use don't live up to the new standards.


The new ordinance will not only deal with construction of new tank farms, but also with preventive inspection and maintenance of the older ones. State law determines the current inspection cycle, and it will not be changed by the new ordinance.


"In 1994, the state passed above-ground tank regulations based on a regulation called the American Petroleum Industry 653 standard," explains Miller. "These regulations say that tanks should be inspected as soon as you can get to them after they are built, and then periodically based on corrosion, but no less frequently than every five years." All tank owners in Spokane are following this rule, and by 2007 all the larger tanks will have been through the initial inspection.


"An inspection is a big deal, because the companies must empty the tanks and clean them out and visually inspect them from the inside and out," says Miller. "The tank owners know how long the tank has been in service and the rate of corrosion we see then determines the next inspection. What we are talking about doing with this new ordinance is that when the inspection is done and it triggers changes, then we would have them get the work done right at that same time. But we won't change the inspection cycle as it's determined by the state law."


Miller says tank owners in Spokane have been cooperative so far and that some of the companies are already doing more than required of them to secure the tanks' sites.


"Because of some contamination that's already here, the industry is doing more than they actually have to, to protect the environment and keep the tanks under surveillance," says Miller. "Exxon coats the inside of their tanks with an epoxy fiberglass mixture. Conoco is doing that on some of its tanks, as well. Tosco is putting in double bottoms in some of its tanks on North Market Street." None of the tank owners returned phone calls requesting more information about their improvements, but it's a safe bet that new ordinances could mean higher operating costs for these businesses -- a concern that could surface at the public hearings this fall.





But is there really any way of making sure both old and new tank farms are safe? Todd Fitzsimmons of the storage tank construction company Fitzsimmons Systems in Tully, N. Y., says yes, but there is little agreement on what exactly needs to be addressed in ordinances and laws.


"New York state was the first to adopt above-ground storage tank regulations back in 1992. That was following the Ashland spill in which a whole large tank just let go," he explains. "It was a new installation of a reconditioned tank that was done wrong, and a worst-case scenario ensued when it let go. There were fires on the river 20 miles away, but nothing like this has happened anywhere since. Small leaks and overfills are much more common."


To address smaller leaks and overfills in existing tanks, Fitzsimmons is not a proponent of liners, since these can only be installed around existing tanks.


"Many of the liner systems that were required by the state have failed since then. They must be maintained, and that wasn't always done, and the tank bottoms where not contained by them either," he says. "The bottoms are where most leaks occur. New double-wall tank bottoms with leak detection are a lot more efficient and far less expensive."


Another problem with liners of either PVC or concrete is what to do with stormwater.


"Stormwater is a big issue in this area when it really rains," says Miller. "The water would collect in the tank farms, and whatever petroleum product has been spilled in the area is going to be washed out with the stormwater. The stormwater would have to be treated in little treatment plants before we could let it out into the surrounding environment. But maybe evaporation ponds, if designed correctly, could take care of that problem."





While many details remain to be worked out before an ordinance change could be proposed to the county commissioners, Roskelley knows what he wants.


"The standards for new tanks are going to be pretty stringent, requiring state-of-the-art, three-layer protection, double-tank bottoms, and a leakproof bermed area, which all together should be able to hold 110 percent of what the tank contains," he says. "Most new tanks have a double bottom or fiberglass lining, and we are going to suggest something like this for all the existing tanks, as well."


But Miller says it's important not to give too many specific and detailed regulations, since they may backfire.


"If we ask for a 15-millimeter lining and that isn't enough to retain what's in the tank, or if we ask for PVC and that is being attacked by the gasoline, for instance, then the tank owner can be following the ordinance without it making any difference and without us being able to enforce it regardless if it fails."


Both believe the existing ordinance can be updated, however, and that both new and old tanks can be kept as safe as possible.


"Existing tanks are the real problem; you can't just lift them up and tug a liner underneath them," says Roskelley. "But I do believe newer and more stringent regulations should protect us very well."