Loss monitoring requirements are included in the Environmental Management and Pollution Control (Underground Petroleum Storage Systems) Regulations 2010 (UPSS Regulations) in an effort to detect leaks from the storage system as soon as practicable. If leaks are detected promptly the potential for contamination and harm to the environment and human health, along with the cost to remediate should be reduced.
The UPSS Regulations require that system operators ensure that loss monitoring commences:
- immediately for newly installed storage systems; or
- by 31 March 2011 for storage systems that were in use on 31 March 2010.
The loss monitoring records are not supplied to the EPA Division but must be kept for 10 years in a form that is accessible if the Division audits the site.
Small Storage Systems
A small storage system is a storage system where the tank has a capacity of less than 5 500 litres and is the only storage system situated on a parcel of land. The system operator must ensure that manual tank gauging is undertaken on small storage systems on at least two occasions, at least four months apart, in each year. The results of the manual tank gauging must be kept by the system operator.
Manual tank gauging involves measuring the level of petroleum in the fuel tank, leaving the storage system for at least 36 hours without petroleum being added or removed, then measuring the petroleum level again. If the difference is greater than 2% of the tank capacity then the system operator must notify the infrastructure owner, prevent further fuel being lost and not use the storage system until it is repaired or replaced. The infrastructure owner must ensure that loss verification occurs in accordance with the UPSS Regulations.
All other storage systems
For all other storage systems the monitoring method must be able to detect a leak of 0.76L/hr (18L per day) or more. This is not an allowable level of loss but it is the industry and government standard set for loss detection.
Generally statistical inventory reconciliation analysis (SIRA) is the monitoring method used to detect a leak of 0.76L/hr. SIRA can also be known as statistical inventory reconciliation method and statistical inventory analysis. Automatic tank gauging in conjunction with a leak monitoring system for product piping (in accordance with Section 4.5.3 of Australian Standard AS 4897-2008) can also be used.
If SIRA is used, inventory data (fuel delivered, fuel used/sold and dip levels) are usually sent to an external company once a month and they run SIRA which statistically analyses the inventory data to determine whether there is a trend in the data indicating a loss. A report is then provided which states whether there has been a loss or not.
One company contacted quoted a cost of $25 per tank per month (with an extra $3 per tank per month charged if the data is sent in on paper).
NOTE: Monetary reconciliation analysis for accountancy processes and determining profit/loss margins related to petroleum sales (e.g. WetStock) is not a suitable substitute for SIRA.
Companies that undertake SIRA
You MUST ensure they use a SIRA method certified as meeting the US EPA standard.
The EPA Division does not endorse the companies listed below but they are the most commonly used SIRA providers in Tasmania:
1. Environmental Management Systems
Phone: 1300 367 783
Fax: 1300 367 785
2. Leighton O’Brien Pty Ltd
Phone: +61 3 9804 2200
You could also find SIRA providers by:
- Asking your fuel distributor – they may have a deal with a certain SIRA provider and can get a cheaper rate.
- Contacting Tasmanian Automobile Chamber of Commerce (TACC)
- Looking on the Service Station Association website – under Business Partners – Environmental Consultants
- Search the internet for "statistical inventory reconciliation" within Australia
The SIRA results must state whether each tank has PASSed, FAILed or whether the data for a tank is INCONCLUSIVE (ie SIRA cannot calculate a PASS or FAIL result). If INCONCLUSIVE results are received for a tank over a number of months the Director EPA is likely to conclude that you are not undertaking loss monitoring in accordance with the UPSS Regulations.
If a loss is detected
If loss monitoring indicates that petroleum is being lost from a storage system then:
- within 14 days the system operator must determine whether the apparent loss is due to inaccurate data.
- if the apparent loss is not due to inaccurate data then the system operator must notify the infrastructure owner; and
- the infrastructure owner must ensure that loss verification occurs in accordance with the UPSS Regulations.
It is essential that daily inventory control is still conducted in order to detect a major system failure. If there is a major failure it needs to be detected as soon as possible rather than waiting potentially more than a month for SIRA to provide a loss result.
Inventory Control is the comparison of: fuel in tank yesterday (from dip readings) + deliveries – sales/use which should equal the amount of fuel in the tank today (from dip readings).
Further information relating to the verification of SIRA methods
Regulation 11(5) of the UPSS regulations requires that the loss monitoring procedure used, for all UPSS which are not small storage systems, is:
- capable of detecting an apparent loss of petroleum from the storage system occurring at a rate of 0.76 litres of petroleum per hour with at least a 95% probability of detection and a 5% or less probability of false detection; and
- capable of detecting an apparent loss of petroleum, at the rate described in paragraph (a), from any component of the storage system; and
- verified as meeting the performance standards specified under paragraphs (1) and (2) by an independent third party, using protocols for system verification approved by the Board.
The Board of the Environment Protection Authority has approved a protocol under regulation 11(6) of the UPSS regulations titled EPA Tasmania - Protocol - Underground Petroleum Storage Systems - Statistical Inventory Reconciliation Analysis.
The purpose of the protocol is to ensure, that if statistical inventory reconciliation analysis (SIRA) is the loss monitoring procedure used by a system operator, then the SIRA method they select has been tested using a standard procedure to ensure that it can detect the rate of loss as required in regulation 11(5).
Double walled tanks
Double walled (secondary containment) tanks are tanks with an inner and outer wall with water or a vacuum between the tank walls (in the interstitial space). By monitoring the interstitial space, leaks should be detected before they are released into the environment. The regulations require that, in addition to loss monitoring, the interstitial space between the two walls in a double walled tank must be monitored on at least two occasions, at least four months apart, in each year.
The date, name of person conducting the monitoring and the results of the monitoring event must be recorded and kept by the system operator.
If interstitial monitoring determines that there is a hole in a wall of a tank then the system operator must notify the infrastructure owner, prevent further fuel being lost and not use the storage system until it is repaired or replaced. The infrastructure owner must ensure that loss verification occurs in accordance with the UPSS Regulations.
 Australian Standard AS 4897 The design, installation and operation of underground petroleum storage systems, issued and published on 5 February 2008.