Planning Advice Note 79: water and drainage

DEVELOPMENT MANAGEMENT ⁷

PRE-APPLICATION DISCUSSIONS

37. Initial pre-application discussions between the prospective developer and Scottish Water will establish whether adequate infrastructure capacity currently exists. If it does not, the applicant should work with Scottish Water and SEPA to identify what options are available to accommodate the new development. These may require the developer to fund enhancement to local infrastructure (less a reasonable cost contribution) and/or Scottish Water to provide additional strategic capacity in its investment programme. Alternatively they may suggest changes to the proposed development.

38. Scottish Ministers intend that prospective applicants for planning permission should be under a duty to engage with local people in pre-application discussions for certain prescribed classes of development. Arrangements and timescales for connection to water supply and waste water networks should also be considered by key stakeholders at this stage. Pre-application discussions are particularly important for developments which have not been included in the development plan, involve different uses, or are on a larger scale than anticipated. The planning authority also has a role in alerting developers to other consents required and any known constraints. Where a private solution is proposed, the developer should work closely with the planning authority and SEPA to establish whether it is suitable.

39. Development Impact Assessments ( DIA) are a mechanism for identifying the scale and nature of development impacts on existing water and waste water infrastructure. Scottish Water will determine the need for a DIA on the basis of a desk-top analysis. The DIA will help to determine the scale of any mitigation work required to overcome development constraints. Where a development proceeds, the cost of the DIA can be taken into account in calculating Scottish Water's contribution in terms of The Provision of Water and Sewerage Services (Reasonable Cost) (Scotland) Regulations 2006.

CONSULTING ON AND DETERMINING THE APPLICATION

40. The Town and Country Planning (General Development Procedure) (Scotland) Order requires the planning authority to consult Scottish Water where a proposed development would be likely to require a material addition to or a material change in the water or waste water services it provides. This will include alterations to the use of land or property which will result in greater demand for water or material changes to the discharge of waste water. The planning authority should ascertain whether the applicant intends to connect to Scottish Water's network or pursue another option.

41. Scottish Water will not, other than in exceptional circumstances, object to an application. Exceptional circumstances might include proposals which could infringe the operation of existing infrastructure, involve Scottish Water in unreasonably high capital and/or maintenance costs, or could raise issues with odours. The absence of an objection should not be interpreted as acceptance that the proposed development can currently be serviced. Scottish Water will consider the proposal, based on the level of detail provided, and advise the applicant and planning authority of the existing capability of their strategic assets along with any local infrastructure considerations that are known at the time of the request for information. This will include advice about the implications for any programmed investment. The response will form Scottish Water's initial views on securing connections via their own consent to connect process. SEPA will consider the proposed development and, where appropriate, advise the authority as to whether discharges from it could be licensed and on strategic drainage issues, in accordance with its policies, including its Policy on Waste Water Drainage in Sewered Areas.

42. The planning authority should be satisfied that proposals would not have an adverse impact on water quality, public health or the environment. Neither should proposals impede the development of a sustainable drainage network. Where the applicant has stated their intention to connect to Scottish Water's network, and Scottish Water has not made an objection, there should be no barrier to granting planning permission in relation to water or waste water infrastructure. Where applicable, the applicant should be advised of the requirement to seek consent from Scottish Water to connect to its network and comply with the environmental regulations stipulated by SEPA. In addition, a condition may be attached to the permission stating that, should the applicant later decide not to connect to Scottish Water's network, any alternative arrangement must be approved by the planning authority. The planning authority should re-consult SEPA in such cases. Such a change may necessitate submission of a fresh application. See also paragraphs 50-53 for considering 'Private Schemes'.

SECURING CONNECTION TO THE WATER AND WASTE WATER NETWORKS

43. The granting of planning permission does not secure connection to public water and waste water infrastructure. It is the responsibility of the developer to liaise with Scottish Water directly to ensure the necessary consent to connect to its network is secured.

44. Scottish Water generally operates on the basis of consent to connect being granted following their design approval of a proposal, which already has obtained planning permission. Where there is spare capacity, it will allow a developer to connect. However, it is possible that between the time an earlier assessment of capacity is made and the time when the developer is ready to connect, Scottish Water will have granted consent for another developer to connect to its network. There is, therefore, no guarantee that capacity identified will remain. Scottish Water will, however, manage the ongoing provision of capacity based on the emerging demand for connections as agreed with developers. This will rely on robust development programmes and effective early engagement.

45. Should there be any infrastructure upgrades required to support new development, this will be subject to the funding arrangements outlined in Annex B. In funding the upgrading of water or waste water infrastructure, a developer may wish to be assured that part of the additional capacity will remain available for subsequent phases of development. In such circumstances, Scottish Water will discuss how to ensure that sufficient capacity can be made available to meet the developer's known needs. Two or more developers may choose to share the costs of upgrading infrastructure. Any legal agreements necessary to deliver the infrastructure are a matter for the developer(s) and Scottish Water.

46. Where a development, which is not anticipated in the development plan, would be likely to take up water supply or drainage capacity required for other sites allocated in the development plan, the planning authority should give careful consideration to the implications for the delivery of the development plan strategy. The planning authority may wish to seek the advice of Scottish Water should this situation arise.

SUSTAINABLE DRAINAGE SYSTEMS

47. Surface water runoff, which combines with waste water, can place a significant and variable burden on waste water treatment works and may increase the risk of flooding. It is now common practice to provide separate systems for foul and surface water. The foul water is piped to the waste water treatment works whilst surface water is piped to the nearest watercourse. However, many older networks have not been designed with sustainable development objectives in mind, and have paid insufficient regard to amenity, landscaping potential, biodiversity considerations, and the impact of potentially polluted runoff on the receiving water body.

48. The aim of Sustainable Drainage Systems ( SuDS) is to mimic natural drainage, encouraging infiltration where appropriate and attenuating both hydraulic and pollutant impacts with minimal adverse impact on people and the environment. Keeping surface water out of the combined system in new development, and the removal of surface water from combined systems in areas being redeveloped, can free up capacity for the treatment of waste water, assist in the removal of development constraints and reduce the frequency of emergency overflows. Regulations ⁸ require SuDS for the majority of new developments and SPP7 Planning and Flooding states that surface water run-off from development should be fully or partially drained by a sustainable drainage system unless this is impracticable. It is also SEPA's policy to promote SuDS as the preferred solution for drainage of surface water run-off, including roof water, for all proposed development, whether greenfield or brownfield. SuDS can be designed as attractive amenity features within developments, to the benefit of the local community.

49. Additional information is provided in Planning Advice Note 61 Sustainable Urban Drainage Systems. The responsibility for maintenance and capital replacement of shared public SuDS is set out in the Water Environment and Water Services (Scotland) Act 2003. The design and construction standards for SuDS systems to be adopted by Scottish Water will be included in the second edition of Scottish Water's Technical Manual 'Sewers For Scotland', which is currently being prepared. In future, where a SuDS system for a proposed development is of a scale or nature appropriate for vestment then the developer and Scottish Water should enter into an agreement on the design and construction standard.