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Fluent in effluence

Review by Frank Cavanagh

Féidhlim Hart’s timely and  practical guide to what he concedes is an “umentionable” activity, one which he notes is ”making the news” gives a very useful overview of the problems associated with sewage treatment and effluent disposal. It is divided into handy foolproof chapters with titles like “How can I tell if my septic tank is working?” (and a subheading “is there effluent on your lawn, or neighbour’s lawn or field”!). and “if it looks ok, do I need to do anything?”.Screen shot 2015-02-10 at 13.37.58

The key concept is that “the combination of a septic tank and a percolation area can be surprisingly effective at dealing with sewage if the tank is installed in such a way as to provide adequate settlement and if the percolation area has a sufficient surface area, an even distribution of effluent and a sufficiently deep layer of unsaturated subsoil of suitable percolation characteristics; i.e. percolation that is not too rapid and not too sluggish. if any element of the above is missing or inadequate, the whole system can fail and either clogs up visibly, causing problems for surface water, or can bypass the treatment process causing problems for groundwater”.

While he endeavours to cover the advantages and disadvantages of various systems, the author – who declares he is “passionate about genuine environmental sustainability” – frankly admits he has “biases” towards solutions that are “natural, zero energy, recycle biomass or nutrients and/or produce a firewood crop at the end of the year”. He favours artificial wetland solutions – his “first love”: “effective wastewater treatment using no electricity, with low construction cost, eminently robust to Irish maintenance habits and providing a natural habitat to boot – what could be better?”.

Stlll, he notes that: “Gravel reed beds, with their more engineered look and need for additional maintenance, nonetheless offer certain advantages over constructed wetlands in certain situations.

Mechanical treatment systems likewise, have certain clear advantages on some sites, despite their greater electricity usage and maintenance requirements.

Most recently, zero-discharge willow facilities have become an option in Ireland, offering a carbon-negative, zero-discharge solution for people who want to build where there is poor percolation and no surface waters to discharge to; or those who just want the firewood and the peace of mind of having no outlet pipe anywhere”.

He cautions that  “your final choices will need to reflect your own values, priorities and site requirements”.

It has been observed that as regards design and installation of septic tanks, the law is most notable in the flouting. Perhaps therefore an important omission in the guide is adequate reference to the legal requirements surrounding any treatment-and-disposal system. Septic tanks are subject to the requirements of the building regulations, which require them to be fit for purpose and to a host of other laws including Health and Safety, Control of Hazardous Substances, General Product Safety, Sale of Goods and Supply of Services, Consumer Protection, Water Services Act etc. It should also be noted that the homeowner is solely liable in law under the Water Services Act 2012 for the consequences of any system failure.

The author makes frequent reference to the EPA Code of Practice and its limited applications. However, some Local Authorities do in fact require rigid adherence to it, regardless of appropriateness, and the fact that the EPA disclaims all responsibility for any adverse consequences of its application is remarkable. Compliance with the EPA document is not even admissible as a defence in law for environmental pollution.

The guide reproduces the EPA treatment-system evaluation sheet which fails to allow analysis of comparative costings over an extended period, e.g. ten or more years. It makes no reference to the long-term maintenance costs of wetland or other systems for example.

Specifically, in relation to ‘mechanical’ submerged fixed film reactor systems, the author mentions their introduction to the market in the early 1990s. Their acceptance and agreement certification were conditional on incorporation of a range of back-up ‘fail-safe’ features to ensure protection of the consumer, public health and the environment. Unfortunately these fail-safes were disregarded and dispensed with, entirely for reasons of  commercial convenience, resulting in a race to the bottom and a plague of pollution, public health and consumer issues.

It is a pity the document does not include reference to these originally required fail-safes, which would have been of practical use to prospective purchasers of such systems – and have them a chance.

All in all, the author deserves credit for producing a well laid-out and readable document which is a useful starting point for anyone considering the use of a system or product to deal with a wastewater problem in an environmental manner. •