Environmental Impact Assessments
(Drainage reports / Pre Auction Surveys)
Development involving the use of Private Sewage Disposal
Central Government in the United Kingdom (to follow in EU shortly) has issued new guidance about planning controls on non - mains sewerage and associated sewerage disposal aspects of future development, so as to avoid environmental, amenity or public health problems which could arise from the inappropriate use of non-mains sewerage systems, particularly those incorporating septic tanks.
This guidance requires the applicant / developer to demonstrate that the proposed sewerage system is appropriate by the submission of a supporting assessment with each planning application which involves such proposals. The factors to be covered in the assessment are as follows:
Contravention of recognised practices:
Any evidence which shows that the proposed arrangements are likely to prejudice, contravene or breach any statute, Regulation, Directive, Code of Practice, Bye law, water quality objective or any other authoritative standard (such as British Standards, the Environment Agency’s ‘Policy and Practice for the Protection of Groundwater’, research papers, reports with proven conclusions).
Adverse effect on water sources / resources:
Any information produced by the British Geological Survey, the Environment Agency (including its predecessor bodies) or any other authoritative sources, which shows that the area has geological formations which could allow the transmission by percolation or by surface run - off of sewage effluent from the proposed foul drainage system directly or indirectly so as to adversely affect any existing or potential surface or groundwater sources used or likely to be used for public or private water supplies or for animal husbandry or agriculture or recreation or the interest of other riparian owners.
Health hazard or nuisance:
Any evidence which indicates that the proposed arrangements and the associated effluent disposal system is likely to lead to a risk to public health or cause a nuisance.
Damage to controlled waters:
Any evidence including reference to information on site hydrology and geology and to Groundwater Regulations, which indicates that the proposed arrangements may result in the entry of any poisonous, noxious or polluting matter or any solid waste matter into any controlled waters, including ground waters to the detriment of water quality.
Damage to the environment and amenity:
Any evidence that the proposed arrangements are likely to lead to raw or partially treated sewage entering into receiving waters or onto land, to such an extent as to damage or undermine the environment and amenity value of the locality or any other area, particularly if it is of special significance such as a Site if Special Scientific Interest (SSI), Area of Outstanding Natural Beauty (AONB) or public open space.
Overloading the existing capacity of the area:
Any authoritative assessment or available records, which indicate that 1. the addition of a new discharge from a proposed development to those which already exist in the area, or 2. the quality or quantity of the new discharge by themselves, are likely to overload the local subsoil soakaway capacity or receiving water to the extent that it may lead to the problems of ponding, sewage flooding, pollution or nuisance.
Absence of suitable outlets:
Any evidence to show that there is no suitable facility such as satisfactory watercourse or adequate land for soakaway in the locality to accommodate the disposal of effluent from the proposed septic tanks / sewage treatment plants serving the new development.
Unsuitable soakage characteristics:
Any results derived from percolation tests which have been carried out in accordance with BS 6297 or a subsequent superseding standard, (preferably carried out in winter conditions when the soils are saturated), which show that the local soil condition would preclude effective disposal of any sewage effluent from the proposed septic tank serving the new development.
High water table:
Any evidence drawn from records of ‘rest water levels’ observed in trial holes which show that the water table in the locality is so high that at any time of the year it could inhibit or impede or adversely affect the proposed foul drainage / effluent disposal arrangements.
Rising ground water levels:
Any evidence, such as water table records of the locality, which show that the levels have been rising consistently and are likely to interfere with the proposed foul drainage / effluent disposal system, or may cause damage to other land or property in the area e.g. by its contribution to land slides or subsidence.
Flooding:
Any evidence, such as records of frequencies and levels of previous flood incidents, which show that the locality is subject to flooding to the extent that the proposed non - mains sewerage would lead or contribute to environmental or amenity problems.
