Household drainage problem areas

Between 5 and 9 percent of properties in the UK are not connected to the public sewerage system for a variety of reasons, but most often because they are remote from core infrastructure areas...

Aug 21st, 2008

Between 5 and 9 percent of properties in the UK are not connected to the public sewerage system for a variety of reasons, but most often because they are remote from core infrastructure areas. These properties rely on private wastewater disposal systems, often by means of septic tanks and soakaways, and sometimes direct discharges to watercourses.

The harm caused to the amenity and environment by these discharges is in some way addressed by Section 101A of the Water Industry Act 1991, which was introduced in 1996 and places a duty on sewerage undertakers to provide public sewerage under certain technical and economic conditions. Faber Maunsell | AECOM has dealt with around 175 applications under this process on behalf of their Water Authority clients, and, in dealing with the Environment Agency, Local Environmental Health Officers, Councillors, Community Councils and members of the public, have become very familiar with the process.

Modern standards of hygiene and cleanliness dictate increasing water usage in most households, but this soon comes into conflict with aged private sewerage disposal systems, and harm to the environment often becomes apparent in these cases. In a country that is generally well provided with the utility services, there is an expectation amongst some property owners that any services that they don't already have will quickly be provided by the utility company on demand, and that the necessary investment will soon be recovered through utility charges. That bijou 'get away from it all' rural property may be polluting the stream that tinkles merrily through the garden by means of the soakaway under the lawn, and the new owners may consider that an application for public sewerage will soon solve their problems.

But the installation of a new First Time Sewerage network is not easy : in comparison with most of the other utilities, pipework is bulky, must be buried, but above all always has to go downhill, unless pumped at major cost back uphill. Payback periods for new public sewerage investment are therefore very long, and unattractive commercially. The economic analysis in the Section 101A assessment process takes account of the cost of the installation of public sewerage, and calls for it to be compared with the value of the environmental benefits arising from the removal of the pollution. In dealing with the many cases they have assessed, Faber Maunsell | AECOM has developed a method for placing a value on the benefits to the environment ensuing from this process.

Water Authorities are also under an obligation to resolve DG5 internal and external flooding of properties connected to the public sewerage system. In these cases, harm is again being caused, and, in cases where householders end up with polluted water inside their properties, it is arguable that this is more distressing than pollution at the bottom of the garden.

Faber Maunsell | AECOM are familiar with both the Section 101A and the DG5 processes and often have teams working side by side dealing with two aspects of the same problem -- the harmful side of our household drainage systems.

August 2008

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