Creating land drainage on heavy clay
Working with blue clay as a foundation to a garden is not without its frustrations; not least, there's the issue of efficient drainage. Our garden is around 20m long and measures nearly 14m at its widest point. it is also on a slight slope over its width and (in a different direction) most of its length.
Given the house is built on what was previously a field used for grazing sheep and where not one thought was put into the creation of gardening with relative ease, the land is riddled with stones both great and small. There's a net work of buttercups and daisies enough to rival the scale of the London Underground and a good measure of clover. Add into the mix a vast array of grasses, moss, a huge albeit beautiful mature beech tree and it becomes quickly apparent as to the potential difficulties when dealing with, among other things, drainage. Oh, and did I mention there is a solid foundation of blue clay. Beyond the depth of a spade it is almost impossible to get to anywhere close to managing without many hours of back breaking digging.
However, where there's a will there's a way. We haven't given up on the garden, on the contrary, it is coming on season by season with much to be admired along the way. One of these fine days I'm determined to have it registered in the famous 'Yellow Book'.
The original drainage system has left a lot to be desired. Once the whereabouts of the main drain which takes surface water from higher up the surrounding mountains had been established (under a pile of builder's rubble, rocks, sand, shale and mare's tail) it was down to more concentrated digging to clear the surrounding area, unblocking this drain so the water could get to the outlet further down the village and assess the next course of action. It soon became clear that there was much to be done if we were to re-route surface water - which would often rise to around 6' deep around the garden shed during heavy rain - despite the appreciation of the local blackbird community for bathing rituals.
The old drainage pipe did not take long to find. Well, it wouldn't when you consider that it appeared to have been tossed onto the ground as an afterthought and covered over with rubble where weeds were at will to flourish in abundance.
A 17m long, knee-deep trench was subsequently dug as the foundation of our new drain. In all, around 9 tonnes of garden rubble, rock and clay was removed to a skip using a spade, a pick axe, a wheelbarrow and a phenomenal amount of leg-work! 'Get a mini digger in!' came the call of those who know better. Aside from difficult access issues, it was just as well that we did not take that possibly sound advice. We discovered along the way, the main sewage drain crossing our trench on route under the lawn and patio. The thought of a mini digger wrestling with that was enough to send shudders down our spines. it also determined the overall depth for the new drain.
Over time, we got through the blue clay and established a gentle slope along the length of the trench towards the main drain. The whole lot was lined with GeoTech membrane enough to encase the drainage pipe resting on washed gravel. Once the pipe was wrapped up entirely, another layer of washed gravel was added to cover the top and fill in around the sides of the trench.
Creating a new footpath along the length of this trench involved fixing treated timber edging boards to wooden pegs driven into the ground at measured intervals. A layer of GeoTech landscape fabric was cut and layered to fit the length and a little over the width of the path. Gravel was used to fill the path before adding a decorative layer of local slate chippings. All in all, a good job done and the finished path is looking great while surface water flooding this part of garden is a thing of the past.