Local Authority Shared Case Study: An Aylesbury housing development demonstrates how Local Authorities should insist on SUDS principles from the outset of master planning.
This is one of a series of case study examples shared by Local Authorities on Engineering Nature’s Way to outline the experiences of local authorities in introducing SUDS principles in their areas.
Introducing SUDS thinking at the master plan stage for the Berryfields development back in 2002 provided the essential structure for the detailed planning phases. Aylesbury took a tough stance on SUDS principles from the earliest stages of planning. As a result, the layout of the master plan worked around the natural water flow of the site, draining into the River Thame.
The council’s approach was essential in avoiding potential adoption issues and the key to delivering a satisfactory housing plan from developers which guaranteed effective future maintenance of SUDS features.
The Berryfields development is a 3000 residential home plan with associated light industry, shopping and village school where construction is currently under way (2011). Berryfields is located on the northern perimeter of Aylesbury, on the opposite side of the River Thame to the town. There is an associated floodplain, and Berryfields is adjacent to an earlier 1300 home development.
Local Authority Leadership
Beryl Kemplen, Engineering Manager for Aylesbury Vale District Council shares her experiences. An experienced engineer, with extensive county council background, Beryl has been heading up the AVDC engineering function for several years. She is able to put her insights to excellent use as an in-house consultant on drainage and discharge planning for AVDC’s Development Control Department.
The Role of the Local Authority
“The Berryfields master planning stage started in 2002, at about the time that PPG25 was being applied, but before SUDS guidelines for planning had really been taken on board by Local Authorities. While the existing 1300 home site had had some basic balancing ponds introduced, the opportunity now existed for a more thorough approach. With the backing of the senior landscape architect, I was introduced onto the Berryfields planning process to ensure the best outcomes for drainage from the outset.
“The land had been under agricultural use, with a network of functioning drainage ditches. But the original plan was simply to retain some of the ditches to store water for the existing hedgerows. Without a SUDS plan, this natural resource could have been misused or thrown away. Following my intervention, the external planning consultants invited their own drainage engineer to join the planning process, who became an effective advocate for SUDS on the scheme. As a result, the layout of the master plan worked around the natural water flow of the site, draining into the River Thame.
Early adoption priorities
“It was also important to address adoption of the watercourse network for maintenance during the planning stage. This was a major potential stumbling block that I was pleased have tackled early.
“If left until later, there could have been a post-construction interim where drainage problems were neglected while responsibilities were debated. The result was an agreement with Aylesbury DC adopting the open watercourses across the site. Thames Water agreed to take on the offline ponds and any drainage from these, and Buckinghamshire County Council was to administer the local highways drainage and associated balancing ponds.
Developers on board
“The next stage was to ensure that the developers’ building plans conformed to this vision. Without any SUDS insight, the building plans of the original four developers took little account of the natural drainage of the site. They were looking to enclose and pipe any flow and there was even a proposal to put attenuation basins in the flood plain, a Zone 2 area which was designated for leisure/amenity use. Attenuation basins here would be the first to be flooded, and would offer little control.
“An enforced consultation process with the developers was successful in achieving replanning of the house locations, incorporating essential infrastructure such as refuse vehicle access. Aligning the housing layout to the existing site drainage was essential to retain the open nature of the site watercourses for both surface water management and amenity purposes.
- “Establishing reliable maintenance responsibility for the watercourses, including riparian access was a critical issue. Our previous experience had shown that the maintenance could not be left to the private individuals on the banks of the watercourses. To ensure the drainage function, the developers were persuaded that public access had to be included for the council teams to inspect and maintain them under the provisions of the Land Drainage Act.”
- “At all stages, we worked closely with the Environment Agency, and this was important in ensuring that all the SUDS planning was on track.”
- “In retrospect, I would like to have introduced swales as part of the SUDS treatment train to improve upstream pollution, but in the early 2000s drainage engineering was focused more on capacity issues. It would be different if we were planning the same development today.”
Now Read Beryl Kemplen’s Blog: SUDS the Challenges Ahead for SABS