What is Wetstock?
Wetstock is the liquid fuel contained in controlled storage conditions. Wetstock Reconciliation management is important because of the risk presented by liquid fuels in the event of loss of containment. Petroleum spirit (petrol) is a highly volatile and flammable liquid, which means that at room temperatures it gives off flammable vapours which, when mixed with air, will burn with explosive force if ignited. Petrol vapour can find its way into basements of buildings and public drains with serious consequences, should the vapours come into contact with an ignition source.
The risks around wetstock storage
As most fuel is stored in underground storage tanks, if there are leaks, it is easier for the fuel to enter the underground water system and pollute the groundwater which in many cases provides drinking water to local communities. Given the significant risks to health & safety of people and the environment, the storage of petrol at retail & private stores is controlled by specific legislation which requires such storage to be licenced (in the case of petroleum spirits only) and such licence conditions generally require all practicable steps to be taken to prevent accident by fire, explosion or escape of petrol.
Wetstock Reconciliation is the management of liquid stock, stored on the site, e.g. petrol, diesel, kerosene etc. It is based on the same theory of any stock control system, that is, measuring the amount of stock delivered into the storage tanks, subtracting the amount sold, and measuring what is left in stock. Any variances from what is expected to be in stock may be due to losses (leaks, evaporation, or theft of fuel). To reduce the risks from petrol leaking from an underground tank or pipeline it must be detected at the earliest possible time and any further escape prevented. For new or recently refurbished petrol stations, automatic detection systems can be incorporated into the installation of the underground tank and pipeline in order to monitor for leaks and raise an alarm.
What to do if you detect a significant change in variance.
There are two possibilities – the fuel may have been stolen or you may have a leak. What to do and what appropriate measures to take if a leak is suspected? If you think that you have a leak, as soon as practicable, you must inform your Petroleum Licensing Authority (Local Authority Fire Department) as that is a condition of your licence, and take any action necessary to minimise the Health & Safety risk. You must also inform the Environment section of your local authority, as they will identify any action necessary to protect the environment. Your site should have a written procedure detailing what to do in the event of a suspected leak. This is sometimes called an Escalation Procedure. It should contain details of what action you should take and how to carry out the relevant actions. It should contain details of how to:
- Investigate the cause of the loss
- Contact the Local Authority petroleum licencing and environmental sections
- Take any necessary Health & Safety actions
- Prevent any further leakage
- Quantify the volume of product lost
- Identify the leaking tank or pipework
- Repair the leak or decommission the equipment in agreement with your licensing/ environmental officer
- Remediate any pollution caused in agreement with the Local Authority
Important of communicating with Authority
It is vital that you tell the Local Authority as quickly as possible as they can provide advice on what to do in order to minimise the Health & Safety risks and protect the environment. This advice may include seeking help from specialist wetstock management companies, petrol station contractors, or environmental / oil industry consultants.
Leak investigation “What to do” Checklist This is not an exhaustive list and you should take expert advice as appropriate.
- Carry out a visual inspection of all dispensers and tank manholes for signs of leakage.
- For single wall tanks carry out a static tank test, either via the automatic tank gauge (ATG) if you have one or by a qualified contractor using a precision test method.
- For suction pipework systems, check if there have been reports of dispensers losing prime. This is an indication that the pipeline may be leaking. If so, have it tested.
- For pressurised pipework systems, check that any leak detection device is operational.
- If any other leak sensors are fitted, have them checked.
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