Water and Sewage
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Buildings & land use
Project Summary Project Description Application of Tools Opinion of Tools Decision making process Contact Details

Decision making process

Name of the case study
Nefyn, Morfa Nefyn and Edern Sewage Treatment works

Decision making process - stages
The decision to develop a new sewage treatment works was as the result of the European Directive. The Feasibility study and assessment helped in the decision making process associated with the location for the treatment works, and the route for the transfer main.

Decision making process - levels
Decision on providing a treatment works within the Nefyn area (as opposed to transferring flows to another treatment works outside of Nefyn) was made at commencement of the study. Decision to proceed with the recommended site was made in the following (Outline design) stage.

Decision making process - sources of information
The decisions were made by Welsh Water’s Capital Manager, who is two levels below the Managing Director of the organisation.

Decision making process - who are the decision makers
Time was a barrier to obtaining information during the decision making process.

Decision making process - who made the final decision for project implementation
Capital Manager made the final decision for project implementation. This was assisted by Public Relations and Technical staff.

Name of tool
A feasibility study

Decision making process - tools in decision-making process
The assessments were carried out at the very beginning of the project in order to identify the most efficient sewage treatment works set up for the situation and the best location for the sewage treatment works.

The tools were the deciding factor for the number and location of the sewage treatment works. The tools were designed to incorporate requirements such as the need to have the site close to the existing sewage infrastructure (to avoid the need for pumping) and the need to have a suitable watercourse for discharge of treated effluent. Thus the assessment gave lower rankings to sites which required extensive pumping to transfer flows to the new plant and also to transfer flows back to a suitable point of discharge.

Name of tool
Welsh Water Treatment Works Site Selection Matrix

Decision making process - tools in decision-making process
The reason for using the matrix is to make a decision on the choice of site and also have a record which is auditable. Meetings relating to the matrix comprise about 8 to 12 key people from the project team. The merits and constraints of each of the sites are discussed and the headings to score are agreed. The scoring system eg. 1 to 3 or 1 to 5 etc. is agreed as a team. Good means that this topic is less likely to hinder development of a site or is a cheaper solution and bad means that more problems will have to be overcome in developing the site or that it will cost more. Each person then scores each site under the agreed headings so that an average can be produced, hopefully providing a clear winner!

The site chosen was both adjacent to the existing sewage infrastructure and a suitable watercourse was available for discharge. The watercourse is of high environmental sensitivity and thus the treatment plant chosen (Membrane Biological Reactor) produces a high quality effluent but at significantly higher power consumption than other process which produce lower quality effluent.

The Environment Agency gave an indication of the level of treatment they would expect for a discharge into the watercourse (quantitative benchmark). The study therefore had to consider treatment processes which could achieve this level. Information on the potential levels of treatment for different types of process was obtained from the process plant suppliers.

The tool was used in order to support arguments regarding the development.

Decision making process - how was the information for the dmp disseminated
Two public exhibitions took place during March and November of 2003 with the backing of Nefyn Community Council. Safety presentations have also been made to local schools. Following positive feedback from the public exhibitions planning applications were prepared.

Consultation with Nefyn Community Council revealed that a site on agricultural land east of Edern was selected as the preferred option as it is close to the existing sewerage system, has potential easy access from the main road and is outside the Area of Outstanding Natural Beauty.

Decision making process - how was the public involved

Decision making process - was there public discussion over the project

What tools were used to assess sustainability?

A feasibility study

Welsh Water Treatment Works Site Selection Matrix

More information

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