Waste Water Drainage Consultation Areas

Waste Water Drainage Consultation Areas (WWDCAs) are consultation areas where, due to site conditions, finding an appropriate drainage solution can be more challenging. These will in future be able to be viewed on Scotland's Environment Web and a ZIP file of the GIS layer is available to download.

These areas are not a designation in themselves but act as a trigger for specific drainage issues to be examined more closely.  Consultation with SEPA should only be initiated for proposals which result in the development of new or additional private waste water drainage and only once the following site specific requirements identified in this GIS layer are met and when the correct supporting site investigation information has been obtained.

There are three categories of site specific requirements and these are listed below. The GIS layer will tell you which category applies to each area. Our WWDCA flowchart provides a useful tool to understand the consultation approach.

Requirement Category A1: Area contains poor ground conditions and limited public sewer

Do not consult SEPA where it is proposed to connect to the public sewer.

For all other applications where the GIS layer indicates that connection is likely to be feasible, SEPA objects unless connection is required by condition or an amended application. Only if an applicant submits written evidence as to why connection is not feasible consult SEPA.

For all other applications where the GIS layer indicates that connection is unlikely to be feasible, do not consult SEPA on the private drainage of one or two house developments where the development follows one of the two options below. Both options must be supported by a site investigation that complies with Section 3.9 of the Domestic Technical handbook, including factors such as site slope, distance from sensitive receptors such as drains and wells, depth to seasonally highest water table and percolation rate. Both options must be compliant with the relevant section of Section 3.9.

Option 1 = soakaway without overflow

Option 2 = mound soakaway

Where neither option is achievable, and for all other situations, it is likely that additional treatment will be required. Consult SEPA but only after the applicant has provided a site investigation, compliant with Section 3.9 of the Domestic Technical handbook, and a site layout which shows the proposals for additional treatment such as treatment plant, reed beds or proprietary systems.

Requirement Category A2: Area where First Time Public Sewer is the appropriate solution

Do not consult SEPA where it is proposed to connect to the public sewer.

For all other applications where the GIS layer indicates that connection is likely to be feasible, SEPA objects unless connection is required by condition or an amended application. Only if an applicant submits written evidence as to why connection is not feasible consult SEPA.

For all other applications where the GIS layer indicates that connection is unlikely to be feasible, do not consult SEPA on the private drainage of one or two house developments where the development follows one of the two options below. Both options must be supported by a site investigation that complies with Section 3.9 of the Domestic Technical handbook, including factors such as site slope, distance from sensitive receptors such as drains and wells, depth to seasonally highest water table and percolation rate. Both options must be compliant with the relevant section of Section 3.9.

Option 1 = soakaway without overflow

Option 2 = mound soakaway

Under either option, a condition must be imposed requiring that prior to the commencement of any works, the following scheme and plans must be submitted for the written approval of the planning authority, in consultation with SEPA, with all work being carried out in accordance with the approved scheme. The scheme must contain the following elements:

  • A site plan setting out the details of a temporary private wastewater drainage system;
  • Connection to the public sewerage network as soon as the required upgrades are made available; and
  • Removal of the temporary drainage system when connection to the public sewerage network is achieved.

Where neither option is achievable, and for all other situations, it is likely that additional treatment will be required. Consult SEPA but only after the applicant has provided a site investigation, compliant with Section 3.9 of the Domestic Technical handbook, and a site layout which shows the proposals for additional treatment such as treatment plant, reed beds or proprietary systems, and future connection to the public sewer.

Requirement Category A3: Area contains a loch downgraded due to high levels of phosphorus

Do not consult SEPA where it is proposed to connect to the public sewer.

For all other applications where the GIS layer indicates that connection is likely to be feasible, SEPA objects unless connection is required by condition or an amended application. Only if an applicant submits written evidence as to why connection is not feasible consult SEPA.

For all other applications where the GIS layer indicates that connection is unlikely to be feasible, consult SEPA on all drainage proposals but only after the applicant has provided phosphorus mitigation calculations in accordance with the Addendum to SEPA’s Planning Advice on Waste Water Drainage.

Please remember to add any upgraded drainage systems to your register of drainage systems that have been upgraded in order to offset the proposed additional drainage from new developments.