There was a residual risk of a bulk tanker coming off the proposed embankment within the Wellhead Valley, causing catastrophic long-term contamination of the porous water-bearing ground throughout the valley.

Earth side walls to the embanked road through the Wellhead water source area were to be only 1m high.

However, the underneath of the bulk liquid tank of a fuel transporter is typically 1.5m above road level.

In a serious accident, a toxic liquid load could have been projected off the road and spilt over the side.

Walls were anyway proposed for only a short length in the immediate vicinity of the abstraction borehole.

According to the bypass design drawings, there was to be nothing to stop big vehicles coming off the road within the area of the old Bere’s Mere Farm - which is a field away uphill from the Wellhead water borehole.

Bere's Mere Farm is shown on the previous map on this website.  It is on the edge of the inner water zone.

As you would think, the edge of the ground-water zone is not impervious.   Maps show porous chalk layers, both within and without.  A toxic spillage near the edge would penetrate to the inner water protection zone.

The whole Wellhead Valley is an aquifer.  The sub-strata is all porous, of chalk or sand.  It is all vulnerable.

If built, this main road would have been in use for a long period, with plenty of opportunity for an accident.

A bulk toxic liquid spill (off a road through the valley) could have been disastrous for the water source.