Meades Water Garden: River Chess

The objective of the regeneration project was to bring the site back into management, to create a more sustainable, natural river channel and to improve the gardens both for wildlife and people and to regenerate a valuable urban green space.

The project was delivered in partnership with Chesham Town Council and Impress the Chess.

Due to the size of the project and the time required to develop the river restoration plan, work was split into three phases. The first phase involved carrying out an extensive programme of tree management. Working with the Chiltern Woodlands Project, a schedule of tree work was developed to improve the amount of light reaching the river and to remove dead and diseased trees. With funding in place by August and the necessary permissions obtained (part of the site is covered by a tree preservation order), the tree work was carried out in March 2007.

Alongside the development of a tree management schedule, the CCSP officer with the assistance of the River Restoration Centre (RRC) and the Environment Agency developed a plan for the restoration of the river

The river restoration work began in February 2008 and was completed in two weeks. During this time a footpath closure was put in place and the site fenced.

1. Work began with the removal of the two weirs, which had been used to retain water in the ponds, to allow the site to drain

2. A temporary dam was built at the top of the site  and river flow was piped around the working area. With increasing groundwater  levels it was necessary to use up to three pipes to divert river flow around the site. In addition, because of springs on the site, a pump was required to drain water from the working area. The outflow from the pump was put through a series of screens to minimise silt input into the river downstream of the site.

3. Working from the upstream end of the site a new channel was dug through the accumulated silt following the line of preferential flow. Excavated silt was distributed around the site within the boundary of old ponds to avoid costly removal from site.

4. Working from the upstream end of the site, Nicospan, with posts at 0.5m intervals was installed to provide support to the new channel sides and to ensure separation of the silt from the gravel infill.

5. Unsorted gravel sourced locally, was imported into the new channel to for the new river bed. As a measure to prevent signal crayfish from cutting through the Nicospan, a strip of fine mesh chicken wire was stapled to the posts, before final levelling of the gravel bed. With only 60cm level difference between top and bottom of the site, careful levelling work was required by the contractor to ensure that a gradient was maintained throughout the restored length.

6. With work substantially complete in the upper half of the site, work moved to the lower pool. With the headwaters of the Chess having suffered from low flows in recent years, it was decided not to create two channels but to concentrate flow in one, which would link with the existing course behind the island.

7. The channel through the lower pool was completed by joining it to the newly completed section upstream. The flow diversion was then removed. The left bank was consolidated by scraping silt from the area immediately south of the new channel to create a pond area. A low lying bund was installed in place of the weir at the front of the island to help retain water within wetland area but to allow water to flow out into the river channel in the event of high flows.