Project: Winchester River Enhancement
Client: Winchester City Council (Managed by Hampshire Wildlife Trust)
Aquascience Ltd tendered for a ‘design and build’ contract to enhance two heavily modified reaches of the River Itchen in Winchester City Centre. This project has similarities with the proposed project on the River Welland: The areas formed important focal points for city residents and visitors; the river channel was over sized and constrained by concrete revetments; and access for materials and plant pose d challenges due to the large numbers of people using the public spaces, the proximity of city infrastructure and the sensitivity of landscaped parklands. In addition there was a need to satisfy the EA that proposals would not lead to any increase in existing flood risk.
Aquascience won this tender on the basis of the suitability of the designs, and the innovative methods employed to overcome access challenges and import large volumes of material whilst minimising disruption in these important public areas.
At both sites channel diversity, sinuosity, dynamis m and improvements to aesthetic quality were achieved by the construction of marginal berms which were then planted with characteristic chalk stream species of local provenance.
Access challenges were different for the two sites: at Friarsgate it was necessary to lift all materials (80 tonnes) and machinery from a busy city thoroughfare over a high brick wall. Detailed planning resulted in the operation proceeding safely and with the minimum of disruption; the second site, situated within landscaped gardens, required the import of 160 tonnes of material.
By using our mono-rail system all materials and work was carried out without closing or damaging the park. Indeed the mono-rail became quite an attraction!
At both sites berms were planted with species which would secure them and also add to the aesthetic site value; yellow iris, purple loosestrife, meadowsweet and water figwort were installed with sedge and aquatic grass species to ensure maximum visual impact.
Both these sites had significant challenges to over come. However, experience and detailed planning resulted in an extremely smooth operation within projected timescales and budgets. The satisfaction of Winchester City Council and Wildlife Trust is demonstrated by our invitation to attend initial meetings to discuss phase II works, which will extend the work already completed into other areas of the City.