Project: Avington Park Lake Restoration
Client: Sarah Bullen
WLW Ltd (now Aquascience Ltd) were contracted to write a feasibility study for Avington Lake with the following aims and objectives:
- Identify historically important features and wildlife habitats in and around the broad western portion of Avington Lake.
- Assess the amount of silt removal required for the ecological benefit of the Lake.
- Assess the composition of the silt.
- Consider methods for silt removal from the lake and subsequent disposal of the sediment.
- Provide an assessment of these options on the historic and wildlife value of the Lake and surrounding land, and the feasibility of the work.
- If considered feasible, present an informed and detailed restoration plan that identifies the works required to achieve the restoration objective, taking the historic and environmental factors into consideration.
- Prepare and invite tenders for the restoration work from suitably experienced contractors in order to obtain a competitive cost f or the restoration work.
The report recommended proposals to restore Avington Park Lake and preserve its heritage, landscape, ecological and recreational resources for the future. The various options for de-silting for the benefit of ecology and the historic landscape setting were assessed in terms of how they fulfill the brief, and their impact on the ecological and historical interest of the site. A statement of significance has been compiled to assist with this assessment.
Avington Lake is situated within land registered under the Historic Buildings and Ancient Monuments Act 1953 within the Register of Historic Parks and Gardens by English Heritage for its special historic interest (list entry no. 1000529). The lake is situated so as to be a feature of the long vista from the house. However, the lake had not been maintained to preserve this vista and had accumulated silt and developed emergent vegetation over much of its area. As a result the ecological interest of the lake had increased giving rise to excellent bird habitat which is significant for an inland water body in Hampshire.
An options appraisal and feasibility assessment was carried out into the possible methods of de-siltin g the lake including looking at the composition of the silt and de-silting, storage and disposal methods. The re port proposed that the most suitable method of de-silting was by the partial de-silting of Avington Lake. This will preserve and enhance habitat for bird species while opening up the lake to improve and partially restore the historic interest of its designation. The methodology for this restoration option and detailed design s were provided within this report.
The restoration designs strike a balance between the reinstatement of the design intent of the lake in the landscape whilst preserving and enhancing the lake’s wildlife habitats. Some habitat features are ret ained but the removal of silt does reduce the extent of areas utilised by a number of bird species. This is mitigated by the creation of more diverse habitats within the lake’s boundaries and will lead to greater species di versity. The hypothesis was that the lake is a source of phosphorous which damages the River Itchen Special Are a of Conservation was not supported by our investigation s. However it was concluded that the lake traps solar radiation leading to a rise in water temperatures a t the outlet. Consequently the designs incorporate an ‘off- line’ channel to segregate the lake body from the Itchen system and increase the river’s resilience to climate change.