Drainage

With thanks to the National Library of Scotland

I have mentioned the puddles which form after heavy rain underneath the railway bridge over what is now West Street, at the bottom of West Hill, just off the western end of Epsom High Street. A bridge which will shortly be closed for a fortnight while they have another go at the drainage - which I have always imagined to be a large hole bored into the chalk below. A hole which acts as a soakaway but which needs to be cleared of all the debris which washes into it from time to time.

Whatever the case, the subject of a waking dream this Tuesday morning. The workmen were certainly under the bridge, although the layout was not quite what it is in real life. For some reason, I had decided to do a spot of sketching there with India ink and water, something I used to do as a child. So I was set up on a bank on the western side of the bridge, a little above the level of the roadway, sketching away. The water was some way away, under the bridge. When all of a sudden, the workmen did something and the water level rose and the water rapidly headed my way. So rapidly that I had to make a break for it, dropping my bottle of ink on the way.

A little later I went back to where I had been sitting to try and find the bottle, poking around in the now receding water and the mud below. No luck. But I did get a shoe full of water.

I then decided that I needed to be on the other side of the bridge, that is to say the eastern side, and so start to go under the bridge. At which point, the workmen make it quite clear that the road under the bridge is closed. I have to make a detour, starting by getting into a muddle about where the detour is. Eventually it starts to come right and I wake up.

When awake, I start to wonder about what the natural drainage would have been, before the railway. With the low point under the bridge probably a few feet lower than it would have been beforehand. I supposed that the water must flow north, somehow or another, eventually joining the Hogsmill and making its way into the Thames at Kingston. Along with the stream which runs that way up Longmead Road.

The oldest map that I can find at the National Library of Scotland is a six inch map originally surveyed in 1866 and published in 1871. Railway clearly present. Not much in the way of contours, but there are a whole lot of BM's. Which a little investigation reveals to be benchmarks, that is to say heights above datum in feet, measured by difference by chaining them together with a theodolite.

So bottom left we have Stamford Green Pond, still present. From where there is a stream, running more or less due north. Then to the right, West Hill. Then after the hill, the railway and the offending bridge.

Epsom seems to have been built just to the north of the 200 feet contour line, with the land generally falling away to the north, towards the Thames, fifteen miles to the north.

The lowest point seems to be 148 feet at the eastern end of the High Street, the other end from our bridge. So did the water run from west to east, just to the north of what is now the High Street?

Does it then run into the wiggly line which looks like a stream, about where it says 'brickfield', running north, to the left of the left-hand branch of the railway? An impression which is confirmed by looking at the next map up, which suggests that this stream does indeed run north into the Hogsmill, a little to the north west of what is now Ewell Village. With the Hogsmill running roughly north west, a little below the 100 feet contour line.

On which account, the answer is that the water which is now a deep puddle should flow east, but is now trapped under the bridge, where the road has been lowered, lowered enough to upset the natural flow.

While, as so often is the case, the Longmead industrial and housing estates, built after the war, were built on the low lying land to the north of Epsom which no-one wanted to build on before. Top left on the map above. With the Marsh Barton industrial estate, lying just to the west of the Exe, between Exeter and Exminster, being a larger scale version of the same thing. Exminster being where BH spent the second half of her childhood. Coincidentally, at that time home to one of the Exe Vale cluster of mental hospitals, on much the same lines as the Epsom cluster, if a little more spread out.

PS 1: later: corroboration from BH in the form of her remembering water bubbling up through the pavement from time to time, at the eastern end of the High Street, not far from the 148 feet bench mark. A spring line running east west at the bottom of the downs?

PS 2: a few yards before the Hogsmill reaches the Thames, there is a place which is often full of large fish, clearly visible from the bridge above. Always lying fairly still in the water, pointing upstream, towards Ewell Village. Often admired on our way to the nearby Rose Theatre. Or less often to the Police Station opposite.

Reference 1: https://maps.nls.uk/. The maps.

Reference 2: https://psmv4.blogspot.com/2019/10/valued-friends.html. The fish.