Operation & Maintenance Manual
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P a g e
The water table in winter. Special consideration should be given to installations that will be subject to
high water table pressure or flood conditions. The treatment plant will need to be installed so that it
cannot “float” out of the ground and provision made for continued discharge of treated effluent, should
the discharge pipework/soakaway be under water.
Note
–
failure to maintain the ability to discharge may result in pollution, odour and nuisance and
health hazards, which may lead to legal action. WPL can not be held responsible for failure to
discharge due to poorly designed, constructed or positioned soakaways and discharge pipework
systems.
Siting. The plant must be sited within 30m of heavy vehicle access for de-sludging. The plant should,
where possible, be sited above the high water table mark and above or beyond the flood plain. See items
above and accompanying note. The plant should be sited as far from the habitable parts of the dwelling
as possible. Many local authorities recommend 10m as a minimum, but easements are possible for
smaller sites.
Gas & odour ventilation. WPL recommend that the plant be vented. This can be via the vent pipe,
normally attached to the building, or by additional venting (high or low level) off of the inlet or outlet
pipework or the sample chamber.
Sample point. A safe and adequate sampling point is usually a requirement of the Environment Agency.
This can be an off the shelf item or constructed using standard drainage components. Open pipe
discharges to ditches, watercourses, etc, through pipework of less than 5m in length, do not require a
sampling point if the effluent can be sampled from the end of the pipe.
Electrical supply. A qualified electrician (see Electrical Installation section) should only undertake
electrical installation. A safe and reliable power supply is required at all times, as the air blower is
required to run continuously. Adequate means of air or power failure indication should be provided. This
can be an audible or visual alarm or by regular manual checks.
Due to the health risks associated with raw sewage, WPL recommend that the sewage treatment plant is
not used until the system is complete, commissioned and handed over.
Before carrying out any maintenance or installation work, the equipment must be electrically isolated.
Do not leave covers open for any longer than necessary. Temporary barriers and warning signs should
be erected around any open covers or manholes as appropriate, in particular warning of deep water in
the tanks.
Any visiting personnel must report to site office on arrival and fully acquaint themselves with safety
regulations applicable.