Use of Sewers, Including the Flushing of Disposable Products, Fats, Oils and Greases (FOG) and General Food Waste
Many sewer system operators are finding that the incidence of flooding ‘other causes’ is remaining stubbornly high, this is despite various initiatives to proactively clean sewers and minimise repeat blockages. One of the main reasons for this is the increasing use of sewers as a disposal route for non-sewage items, these can range from wipes and other paper/fabric based products, to food wastes including fats, oils and grease (FOG). Many of the blockage problems caused by these products are in drains and local sewers close to property and, given the planned transfer of ownership/responsibility of many of these private drainage systems, the number of incidents that the sewerage undertaker will need to attend is set to increase.
 Various initiatives are therefore being undertaken to better understand the reason for the disposal of these items and, ultimately, reduce the levels of ‘abuse’ and operational problems. These include research programmes into
CP 290 Fats, Oils and Grease (FOG) - a three year investigation.
Fats, oil and grease (FOG) are a major cause of operational problems for sewer system operators. FOG causes blockages in small diameter pipes and encourages sediment build up in all sewers. It is indirectly responsible for many cases of sewer flooding each year, leading to property damage and pollution incidents. Even when FOG compounds don’t cause sewer system problems, they can result in problems at pumping stations and treatment works inlets.
The associated cost of dealing with FOG related problems is significant; The UK water industry spends an estimated £15 million each year on clearing blockages, with further expenditure needed to clean up flooding incidents. Similar problems and associated costs are found in the sewer systems of many other countries, including the Republic of Ireland.
The results of the proect will allow operators to:
- Significantly reduce the amount of FOG being discharged to sewer; and
- Improve the management and clean up of FOG, once in the system.
This project is investigating all the relevant issues associated with FOG, through four work packages:
- Work Package 1 – Legal Aspects.
- Work Package 2 – Sociological Aspects.
- Work Package 3 – Biological/Chemical Aspects.
- Work Package 4 – Engineering and Operations Aspects
Attention is being given to the important and hitherto largely ignored interrelationships between these different elements to ensure that the best overall strategy is developed. Integrating these various aspects and applying a critical mass of effort, should enable a step change in FOG management.
CP311 The flushing of disposable products.
During the last decade there has been a significant rise in the availability of products that, to most consumers, appear to be disposable via the WC. This has resulted in an equally significant increase in the amount of products being disposed to sewer. Unfortunately this often results in the products blocking drains close to property and, all too often, resulting in sewer flooding.
Additionally, product manufacturers are becoming aware of the problem and are looking to develop a testing protocol to ascertain what is and is not flushable. Currently no protocol exists, either in the UK or overseas.
The project is working with sewer system operators and manufacturers trade associations to develop a testing protocol. Previous experience gained in blockage investigations, product testing and pipe rig blockage testing is being brought together to trial and select suitable tests for the protocol. It is anticipated that this work will go forward to become a protocol agreed jointly by sewer system operators and manufacturers.
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