The Site

The opportunity to remove some of the more modern unsightly buildings gives an opportunity to replace them with new buildings better located and giving more space to the listed building group.

We have looked at a series of options to locate the new buildings assessing the proximity to the listed building group with consideration to the desire to be close so all dwellings can operate as one, but not so close that it cramps the listed building setting.

A ring of vegetated bunds encircle the new and existing buildings and amenity spaces, providing shelter, privacy and security and a soft protective boundary that enhances the heritage and ecology of the site.

The Pond

The main pond will have several functions:

• Weave the water cycle in the landscape and biodiversity proposals;
• Sustainable surface water drainage;
• Flood protection with hosting of proposed floating house
• Harvesting of rainwater for irrigation of the garden, allotments and greenhouses;
• Amenity for swimming and other recreational activities!

The pond will support the creation of varied ecological habitats. On the shallower banks of the lawn side, a pebble / shingle fringe will avoid exposed muddy edges associated with water level variations. The terraces and steeper banks on the bund side will support different planted ecologies.

Water quality will be maintained by recirculating water through planted reed beds, and oxygenation through cascades and splashes. In line with guidance from the SUDS Manual, water depths greater than 1.2m will generally be avoided in the main part of the pond to avoid anoxic conditions and degradation of the water quality. Water depths shallower than 0.6m will also generally be avoided to mitigate the risk of algae blooms. The water quality criteria, water treatment, recirculation system and water sampling regime will need to be confirmed as the design develops and aspirations for usage of the pond are confirmed.

Greater pond depth will be required under the floating house to allow for sufficient depth of float. Design water displacement will be confirmed once the total weight of the house and floating structure is established.

The proposed pond will collect surface water drainage from hard standing areas and attenuate it prior to infiltration into the ground. Should infiltration not be feasible on the site due to clayey ground conditions, surface water discharge to local ditches or watercourses will be explored. Flow rates will be restricted to match existing flow rates from the undeveloped site, in line with local policy from Arun District Council.

The pond will be designed for no surface water flooding for all events up to the 1 in 30 year storm event, and to hold water during extreme events up to the 1 in 100 year + 40% event by allowing controlled flooding around the pond.
Consideration will be given to the control of surface water runoff at source through measures such as porous pavements and localised roadside swales and ditches to collect, treat and infiltrate runoff from the access roads.

The pond will be above anticipated groundwater level. It is understood that the ground is semi permeable and therefore it will need to be lined to prevent the loss of water via infiltration. A bentonite liner is proposed. It is a low impact product and self-healing if punctured. Sand and soil will be placed on top of the liner. We expect the liner to be safely above high groundwater levels but if on review of future ground investigation results there is a risk of uplift, a pressure relief overflow well will be considered.

Rainwater will be harvested, with the provision of a dedicated storage depth within the pond as illustrated below. We anticipate that a 150-200mm depth would allow harvesting sufficient water to compensate for evaporation and liner losses, and provide water for irrigation of the garden and greenhouse. This is a material and cost effective way of harvesting rainwater.