BONFIRE HILL DRAINAGE ISSUES – PLANNING APPLICATION WA/2020/0363 (BONFIRE HILL) 1 I refer to your correspondence with Waverley Borough Council (WBC) in connection with the above planning application. I should explain that I am Chairman of Elstead Parish Council, which has serious concerns about the adverse impact of this proposed development on flood management in the village. 2 In your latest letter you say SCC as the Lead Local Flood Authority has no objection to the application, provided an acceptable SUDS scheme is put in place. I am not sure how familiar you are with the Bonfire Hill site, but I should explain that it is an area of elevated land which dominates the centre of the village of Elstead. It contains numerous springs and many of the names of the surrounding roads (Springfield, Springhill, Springhaven) reflect this characteristic of the land. In wet weather, the springs flow mainly to the north, north-west, and north-east towards the lower lying centre of the village, depositing large amounts of surface water into the quite inadequate ordinary water courses adjacent to the highways. 3 During recent flood events (notably this winter, in 2013/4 and in 2001) the amounts of water coming off Bonfire Hill have led to serious flooding of gardens, roads and on occasion dwellings in the village, in spite of action taken by residents to dispose of the excess. Your colleagues in SCC in highways and in flood control (Steve Lindsey Clark and Ian Fowler) will be very familiar with the issue. One neighbour has reported that in February this year he had to deploy pumps to remove floodwater at the rate of at least 5.6 litres/sec coming from just one of the many springs on Bonfire Hill, over a period of several days. 4 The proposed development would involve the construction of 30 dwellings around the lower slopes to the north, north-west and north-east of the site (ie cutting across the direction of flow of most of the springs). The drainage survey commissioned by the developer has determined that the surface water arising from the land cannot be disposed of using infiltration techniques, so the proposal is that this water (which will inevitably increase as a result of the construction of impermeable surfaces arising from the development) should be released into the foul drainage at a rate not exceeding 4 litres/sec. This is the maximum flow which Thames Water, the foul drainage authority, has agreed to accept. 5 It seems from the documents submitted by the developer and your own comments that no surveys have been carried out of the specific hydrology of the site. The calculations provided by the developer suggest that the amount of surface water to be disposed of is based simply on the area of land on the development site. In fact, the topography of the site and the adjacent land suggests that much of the water coming off the hill arises from the even more elevated land to the south, where the land continues to…