We appreciate the need for flood works in the Dulwich / Herne Hill area if no other practical and economic solution has been found and the idea of a ‘super sewer’ rejected after extensive research and studies has proved it to be unviable.
The proposals for Dulwich Park have continually changed and evolved through the consultation period and the plans as submitted vary from those we last saw. Given the Heritage Listing of the Park we would prefer no works to be undertaken, as the long term benefits to the Park from the proposals are limited, and in the short term there will be considerable disruption.
The scheme itself is described as a ‘pilot scheme’, which suggests it is something of an experiment and we cannot be certain on whether it will work in practice. (We are also not able to comment on the technical elements.)
Dulwich Park is an important historical park and if it is chosen as a location for flood measures they will need to be sensitively undertaken. Some key factors we should like to ensure are taken into account are:
- not altering the character of the Park
- respect for the existing horticulture and wildlife habitats. The timing of the works needs to take into account bird nesting, conservation, bat roost and foraging issues
- protection of elements directly impacted by the works – for example, great care will need to be taken in raising the path beside the lake to avoid affecting the landmark boundary oak which is irreplaceable and predates the Park
- the impact on the biodiversity of the lake, which should be investigated before lowering the level of water in the lake
- treatment of the bunds – these will materially alter the appearance of the Park and their impact will need to be softened e.g. by wildflower banks
- the importance of proper land drainage into the new geocellular tanks
- if the Park is to be used to hold back water for a period of up to 48 hours in the event of a 1 in 75 year flood, the exit drainage must be appropriately specified to accommodate the volume of water once released. We are concerned that the bunds may hold more water in the Park during all periods of weather, not only in major storms leaving areas of grass that are important informal recreation places unusable for large parts of the year.
- any drainage system will be effective only if there is a regular maintenance programme for inspection and clearing of drains. This is already a problem with existing drainage. What provision will there be to ensure this occurs regularly in the future, to both new and existing?
- installing sand traps in the horse ride and provision for clearance so that drains are not blocked by silt or sand in the future (this occurs regularly at present)
Finally, the heights of the new bunds and raised carriageway have been precisely given by the project team. We consider that there should be an independent verification after the works are carried out to satisfy all parties that those levels have not been exceeded – this is a material issue, as greater heights will lead to higher water levels and therefore greater ‘spread’.
Chair Dulwich Park Friends