Information about Underground Storage Tanks (UST) for Utility Locators.

What is a Underground Storage Tank (UST) or also know as Underground Storage System (USS)?

Underground storage tank (UST), according to United States, United Kingdom, Canadian and Australian regulations, is defines as, a storage tank, not including any underground piping connected to the tank, that has at least 10 percent of its volume underground. They are sometimes referred to as Underground storage systems (USS). These are the main types of underground storage tanks, but there are many different types, sizes, applications of USTs. Always consult with a professional services, if assistants is required for more information.


Underground Septic Tanks

There are many types of underground septic tanks systems, they can be thought as conventional and alternative. Most underground septic tanks are either holding the sewage to be moved off site for treatment, or underground septic tanks that disperse the sewage on site for more natural filtration and treatment. The septic tanks that are just a hold for sewage in most cases have low voltage power supplies for alarms, grinders/cutters and pumps. However, some septic tanks have pipes or drains with vents over a larger space to naturally filter sewage onsite. I strongly suggest to know what system you are trying to locate and talk to the owner about any knowledge they might have.

As a Utility Locator, Remember to locate the Inlet pipe or Inspection Opening from source of sewage, the access risers and manholes to the main tanks, and any outlet pipes to overflow or drainage fields, onsite knowledge from owners, and past documentation can help with the type of system your trying to locate.

Some more information about septic tanks.

https://www.epa.gov/septic/types-septic-systems

https://www.waternsw.com.au/__data/assets/pdf_file/0005/114809/Section-3-Septic-Tanks.pdf

https://www.globaltanks.com.au/water-storage-tanks/domestic-underground-tanks/


Underground Water Tanks

Underwater water tanks are used in residential properties to commercial sites and everything in between, Such as parks. Much older or larger tanks may be steel, aluminum or concrete based, but newer small tanks are usually made of fiberglass or polyethylene plastics.

GPR can usually pickup clear signals from metal tanks, and can sometimes distinguish the edge of tanks not only if by there material but the change in geology such as the buried back fill used like gravel to clay surrounding the tank.


Underground Stormwater Drainage Detention Tanks

Underground Stormwater Detention Tanks control the flow of rain water through large underground tanks to stormwater pipes. I remember a small unit block having such a system on site, this underground concrete chamber was standing height of about 2 meters and about 5 meters wide and about 10 meters in length. I remember thinking it was surprising large compared to the property size, however this residential property had about 15 small units and a small car park, but alot of the property had concrete driveways and paths with about 5 car spaces. They can be on small residential properties to more often large commercial properties. Large storm water collection sites (fields, parks, car parks) will most likely have some underground drainage detention tank systems.


Underground Petroleum (Petrol/Fuel) Tanks.

Petroleum products stored underground are referred to as underground petroleum storage systems (UPSS).

TIP: LPG pipelines/tanks and Vapor Recovery pipe lines/tanks/units are also common place with service stations underground utilities.

The main things to remember to check for are, but not limited to:

-Petrol/LPG/Diesel tanks (USTs)

-Petrol pipelines to dispensers nozzles (petrol bowsers)

-Petrol and gas Pipelines to vapor control units and vents

-LPG pipelines

-Power and communication lines to mechanizes such as alarms, leak detection units etc.

-Discharge pipes, Spill buckets, Inspection ports.

-Vertical Vapor and water Monitoring Wells.

Any underground petrol, chemical or fuel tank will have documentation of some kind, maps and reports are vital in making sure a utility locator does a good job for anyone working within these areas. In rare cases it might have been lost or improperly documented due to lack of regulatory concerns on private property, always adhere to your swms before any utility locate on these sites, and complete jsea and consult with OH&S regulation standards before any recommendations are made for potholing or to proceed with any work activity. This may only take 20 minutes and will increase safety and injury prevention, and possible avoid environmental and other damages caused by lake of analysis.


Underground Pressurized Air Tanks

Underground pressurized Air Tanks have many uses, such as for on commercial sites that use large amounts of compressed air. These sites might include small tools, like rock drills, nail guns, paint sprayers, blast cleaners, and much more. The larger sites might have machinery use cases such as forklifts, farm equipment to commercial factories and buildings themselves.

Trompe systems use water, gravity and air to compress air in large underground storage tanks that are not that common.

Newer applications and technology such as Compressed-air energy storage (CAES), is compressed air energy storage technology is used with power station or distribution sites to store air pressure created from thermal energy of transporting power.

https://en.wikipedia.org/wiki/Compressed-air_energy_storage


Sources:

https://en.wikipedia.org/wiki/Underground_storage_tank

https://www.epa.sa.gov.au/environmental_info/site_contamination/underground-storage-systems

https://www.spec-net.com.au/press/0214/atl_120214/Underground-Rainwater-Tanks-Sydney-Atlantis-Corporation

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