Environmental Statement volume 4 - Chiltern Evergreen3

Avoids impacting upon both a Scheduled Ancient Monument and existingresidential and equestrian properties;It maintains access to the MoD Bicester sidings; andenables the infrastructure for the rail approach to Bicester Town Station.It is therefore proposed that the justification above enables the development site to passthe Sequential Test. It is clear that there are no reasonably alternative sites, given therequirement for a railway crossing point in the immediate area to compensate for theclosure of the Langford Lane level crossing.The Exception Test must also be satisfied, as the development is in Flood Zone 3.The site is on not on previously-developed land. It is demonstrated above thatthere are no reasonably alternative sites on previously-developed land.A Level 3 FRA is required to demonstrate that the development will neitherobstruct flood flows across the floodplain nor consume floodplain storage; if notthen this work must quantify the mitigation required.The main features of the proposed works are the embankments associated with theoverbridge and the crossings of a number of drainage channels and brooks. The majorityof the footprint of the overbridge lies within a dry island classified as Flood Zone 1, andthe potential obstruction to flood flows can be addressed through the provision ofdrainage through the proposed road.Appropriate mitigation will be provided for demonstrable loss of floodplain storage andobstruction to flood flows, in agreement with the Environment Agency.The proposed road crosses the Langford Brook and a number of minor drainage ditches.The Langford Brook is a main river and hence the Environment Agency is likely to requirethat a clear-span bridge is used for the crossing as opposed to a culvert. The LangfordBrook crossing will require an EA Flood Defence Consent. The other crossings mayrequire local authority consent. All consent conditions will be integrated into theConstruction Method Statement.The preliminary surface water runoff assessment is presented within Section 4. Giventhe extensive use of greenfield land for this aspect of the scheme, it is considered thatthere is significant potential for mitigation of surface water runoff from the road usingappropriate SUDS. For the lengths of new road, it is suggested that these are swales,which would have not only flood risk benefits (reducing runoff to greenfield rates), butwould also minimise the potential for any impacts to water quality as a result of roadrunoff, and may offer ecological benefits (niche habitats may be provided or maydevelop over time).3.5.6 AP7 – Merton FootbridgeThe development site lies within Flood Zone 3, and the Sequential Test has thereforebeen applied. The alternative options have been examined. The reasons for rejection ofthese options were as follows:1. To lose the level crossing without replacement. This was not feasible as it wouldhave an unacceptable impact on the public footpath network;2. Retain and upgrade the existing crossing to standards required for the increasedline speed. This was rejected due to the increased safety risk resulting from theincreased speed and frequency of trains using the line;3. Close the existing level crossing and divert the footpath via an overbridgeadjacent to Holts Farm. The length of this diversion is considered excessive inrelation to the function of the footpath within the local footpath network.32