A number of West Adderbury residents have recently contacted Cherwell District Council with concerns that the drainage scheme being implemented on the Milton Road field is NOT the approved scheme, but a cheaper alternative.
The drainage scheme approved by Cherwell District Council (under planning application 18/00220/F, condition 3) is designed by Forge Engineering (see documents FEDs Drg. Nos. 218132-001 Rev A and 218132-002-Rev A). The approved drainage scheme includes an attenuation basin designed to ensure that adequate attenuation (i.e. storage and gradual release of water) and infiltration are in place to protect the village from a flood event that will cause damage and significant harm.
However, to date none of the approved drainage works have been commenced. Instead, the work being carried out appears to be a drainage scheme produced by DW Clark (see Drg No. 777.2). This is not a consented scheme. The DW Clark scheme consists of drainage that discharges rainwater to a simple soakaway in the north east corner of the Milton Road field, rather than to the infiltration basin designed by Forge Engineering. Discharge straight to the groundwater aquifer via a soakaway, with no attenuation, will increase the risk of significant flooding elsewhere.
How can rain falling on the Milton Road site cause flooding in other parts of West Adderbury? Because the ditch at the back of the Milton Road field, to which all rainwater from the site will discharge, runs down towards Adderbury cemetery where it meets a field drain. This drain passes underneath houses on Horn Hill Road, then runs along Round Close Road before emerging as a small stream that runs through the land behind the old Catholic Chapel. The stream flows back into an underground drain, across the Lucy Plackett playing field and discharges into the Sor Brook.
This underground connection between the Milton Road land, cemetery and Round Close Road is described below by Mrs Diane Bratt, Chair of Adderbury Parish Council, in her comments on a proposed redevelopment of the Catholic Chapel site in 2016 (which was different to the current development).
Many of you will be aware that the area to the west of Horn Hill Road contains a number of natural springs. These do not come to the surface, but flow into the field drain several metres below the ground. You may also know of the problems with high groundwater levels in Adderbury cemetery, behind the Friends’ Meeting House. For new burials, it is often necessary to pump out the grave just before the funeral, so that mourners do not have to see their loved one lowered into a pool of stagnant, dirty water. For this reason, land which has recently been acquired by the Parish Council behind the existing cemetery cannot be used for burials.
And if you live on Horn Hill Road, Tanners Lane or Road Close Road this field drain may already be a matter of some concern for you. A few years ago, the drain became blocked. With nowhere to go, water from the Milton Road field, the cemetery and the natural springs came to the surface, causing serious flooding to the ground floor of at least one property on Horn Hill Road.
The blockage of the drain also caused flooding to properties along Round Close Road and Tanners Lane, as shown below.
To be clear, this flooding was not the result of the Sor Brook breaking its banks, which has led to flooding along Dog Close and over the Lucy Plackett playing field in recent years. It is entirely the result of a blockage somewhere along the route of this small field drain, which is so important to the drainage of West Adderbury.
It is therefore very disappointing that contractors working for Adderbury Parish Council do not appear to be implementing a scheme which would avoid placing additional load on this small drain. If this scheme is not implemented, then it’s likely that water will flow even more quickly into the drain, leading to an increased risk of flooding in West Adderbury.