Leaking tank

Tank bottom slope is important because sediment, water, and heavy phases settle at the bottom. Corrosion is usually the most severe at the bottom, and the design of the bottom can have a significant effect on the life of the tank. In addition, if the Hquid stock is changed, it is usually desirable to remove as much as the previous stock as possible. Therefore, designs that allow for the removal of water or stock and the ease of tank cleaning have evolved. In addition, specialized tank bottoms have resulted from the need to monitor and detect leaks. Tank bottoms in contact with the soil or foundations are one of the primary sources of leaks from aboveground tanks. 

By listening to the sound emitted from leaking tanks, it is possible to estimate not only the existence of, but also the location of, leaks in tank bottoms. Much work needs to be done in this area before it can be considered rehable. 

Of the 44 states that reported testing for MTBE at leaking tank sites, 35 states reported finding MTBE in the groundwater at least 20% of the time they sampled for it. Twenty-four states reported finding MTBE at least 60% of the time.9... 

Vapor released from spills can be minimized by designing dikes so that flammable and toxic materials will not accumulate around leaking tanks. Smaller tanks also reduce the hazards of a release. 

In the case of a facility that has multiple tanks in close proximity to each other, different tracer compounds can be used so that sample analysis will rapidly identify a specific leaking tank. 

Governmental regulations concerning buried tanks are becoming more and more strict. This is because of the large number of leaking tanks that have been identified as causing adverse environmental and human health problems. 

When a leaking tank has contaminated a site or an aquifer, or an accidental spill occurs, the only option is remediation, that is, cleaning-up the site or any other environmental space that has been polluted. This remediation will often be performed by applying chemical processes to transform those undesirable substances either on- or off-site (e.g., by normal extraction and treatment techniques) using biochemical reactions with microorganisms, chemical oxidation, stabilization, or other advanced technologies. 

One of the tanks containing cooling coils always remains empty to serve as a spare thus, if a leak develops, the contents of the leaking tank can be transferred to the spare. A freeboard volume equivalent to 300,000 gal is also retained in the sum of the other seven cooled tanks so that the liquid from a leaking tank can be distributed among seven tanks instead of all of it going to the spare tank. In effect, two empty tanks are available for any emergency in the tank farm. 

Fuel oil is pumped into a leaking tank at a rate of 1 liter/min. The hole at the bottom has an effective area of 0.1 cm2. What is the maximum depth that the fuel oil can reach if the tank is initially empty (Note that fuel oil spurts out through the hole with a velocity of >/2 gh, where h is the depth of oil and g is the acceleration due to gravity, 981 cm/sec2.)... 

A leaking tank drips 1,1,1-trichloroethane (TCA) into a small stream at a rate of 10 mg/min. Stream discharge is 10 literAnin, and depth is 25 cm. 

In addition, leaking tanks at a chemical company are believed to have delivered benzene, methylene chloride (CH2CI2), toluene (C6H5CH3), xylene (C6H4(CH3)2) and aliphatic hydrocarbons (see Section 2.7) to the subsurface water. These toxic (some carcinogenic) chemicals vaporize in the cave atmosphere, collect at traps and then rise into homes in a similar way to petroleum fumes. 

If the zone within the barrier wall holds a leaking tank or drum, and this still holds contaminant, treatment is often started by placing a pipe to the tank from the surface, and either pumping out the contaminant or pumping in a material to neutralize it. The contaminated soil surrounding the tank is then treated by other methods. 

Despite proper choice of tank material and chemical conditions, continuous leak monitoring is required. Two safety features have to be provided to keep leak incidents under control. The tank has to be located in a vault that is able to hold the entire tank volume, and the tank has to be connected to an empty spare tank ready to receive the content of a leaking tank. 

A tank car placarded empty, which contained an estimated 800 gal of anhydrous hydrogen fluoride, a corrosive liquid, was found leaking in a rail yard. Empty or residue placarded tank cars, as they are now called, can have as much as 3000 gallons of product still in the tank if it has not been purged. Responders attempted to control the leak over a 4-hour period. In the meantime, a vapor cloud formed and traveled approximately 2.5 miles downwind. This forced the evacuation of 1500 people from a 1.1-sq-mile radius around the leaking tank car for 9 hours. Local hospitals treated approximately 75 people for minor skin and eye irritations. 

Dikes and curbs—are simple devices that contain or direct spills. Dikes encircle storage tanks and should be able to contain the entire contents of the ruptured or leaking tank. Curbs are essentially mini-dikes that contain and/or direct small spills to sewer. 

It is better to keep a storage tank empty always so that the fluid from a leaking tank or container can be immediately transferred—thus preventing an accident. 

A few weeks later the federal Centers for Disease Control and Preventions reported that a second chemical made up 5 jDercent of the contents of the leaking tank. It was polyglycol ethers, PPH, less hazardous than the main chemical. 

Keep one tank always empty to transfer from leaking tank. 

The OPA also set a schedule for the gradual phase-in of a double-hull design providing an additional layer between the oil tanks and the ocean. While a double hull would likely not have prevented the Exxon Valdez disaster (in fact, some of the leaking tanks were already within a double-hull structure), a Coast Guard study estimated that it would have cut the amount of oil spUled by 60 percent. All tankers traveling through the same area are scheduled to be double-huUed by 2015. 

It is illegal to ship a defective or leaking tank car. If a car cannot be put into suitable condition for shipping, notify the proper company personnel and request instructions. In some cases, the tank car owner will be the proper person to contact for assistance. 

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