Surface water drains normally discharge to a watercourse so it is easy to understand how a spill can end up in the local river. If the correct equipment is not installed within your drainage network, contamination of surface water by oil is a real risk.
In order to assist you in the prevention of such incidents the Environment Agency have produced guidelines which provide advice on "sustainable drainage systems (SUDS)". Referring to their Pollution Prevention Guidelines 3 is a good starting point.
There are many reasons that a spill might occur from leaks and accidental spillage to larger incidents that may occur from deliveries and vandalism. Oil separators or interceptors are installed within the surface water draiange systems to prevent oil pollution reaching the watercourse.
Their function is to separate the oil from the water that is flowing through your drainage system, and then retaining the oil safely until it is removed. To be effective, oil separators need to be correctly designed, installed monitored and maintained.
You should have a separator tank if you meet any of the following criteria:
- Car parks typically larger than 800m2 in area or for 50 or more car parking spaces
- Smaller car parks discharging to a sensitive environment
- Areas where goods vehicles are parked or maneuvered
- Vehicle maintenance areas roads
- Industrial sites where oil is stored or used refueling facilities
- Any other site with a risk of oil contamination
- We can help you install, upgrade or maintain a separator
You need to ensure that you have the correct tank size and design for your site. The type of separator which you require depends on a number of key areas including expected volumes, what you have stored, type of infrastructure and amount being stored.
We offer a full range of separators including:
- Full Retention separators - Full retention separators/ interceptors treat the full flow of water through the drains.
This flow is usually generated by rainfall and dependant on the size of the tank the capacity can be up to a rate of 65mm/hr.
On larger sites, some short term flooding can occur. These separators can help to limit the flow rate making full retention systems suitable for this purpose.
- Bypass separators - Bypass separators/interceptors will treat all flows of rainfall for rates of up to 6.5mm/hr covering over 99% of rainfall events. Anything above this rate will by- pass the separator.
Upon assessment, calculations are made to determine the likelihood of a large spillage and heavy rainfall or flooding at the same time. If the risk is considered to be low then full water treatment is not needed and a bypass separator will be installed.
- Forecourt separators - Forecourt separators/interceptors must be full retention. The size of the separator is determined by the quantity of fuel that is held on site and therefore at risk of a spill or leak.
Spillages on these sites are likely to occur during refuelling and delivery so calculations are made to ensure that a full capacity spill can be contained. This has to include customer spills, vandalism and a full tanker compartment of up to 7,600 litres.
- Washdown and silt separators - This system is used in vehicle and plant wash areas and other cleaning facilities that discharge the dirty water directly into a foul sewer.
We provide a team which will offer expert advice from initial survey through to final installation and commissioning. All of the civil work will be carried out by us ensuring a professional and complete job.
As part of the PPG’s, there are number of actions which you should undertake on a regular basis such as:
- Coalescing Filter changes to ensure the water exiting is within Environment Agency guidelines
- Internal Tank Expectations (every 5 years)
- Integrity checks