A steep problem

[AJ113]

Hello all, firstly may I congratulate Tony and anyone else involved in this site on a first class job. Not only is it useful and informative, but it is presented in a professional manner.

So to my problem:

I have a house in Bulgaria(!) which stands halfway up a 25m hill in an acre of land. Facing the garden there is another large hill that declines towards my garden. When it rains the bottom of my garden becomes flooded as that is basically where the foot of the two hills meet.

I have a sceptic tank which is roughly about 10m up the hill. There is no sewerage at all in the village, there is nowhere to direct water if I was to install a drain of some description.

The best I can think of is to simply dig a ditch along the bottom edge of the garden (which is 57m). I know it will basically be just a long sump that is never drained, but perhaps it would nevertheless keep my garden from flooding.

The hill facing my house is steeper and higher than my own land. A builder in Bulgaria has suggested that most of the flood water comes off the larger hill, therefore a subterraneous wall on my garden border, extending 600mm below ground, and 300mm above ground would go a long way to resolving the problem. I'm not convinced. Any suggestions?

[Tony McC]

Does this valley, where the two hills meet, flow in one direction or t'other? It's hard to imagine a valley that is flat along its long section.

The wall is a nonsense idea, subtrerranean or not. A ditch is a better option but what is really needd is a swale, a ditch that dries up as soon as it's allowed the water to percolate down to the ground beneath. You might need to dig a ditch, say, 1.5-1.8m deep, and then backfill it to, say, -500mm with an 'improved' material, such as a sandy loam, that will allow it to "drain".

There's a bit about swales (and other SUDS technology) on the Suds Intro page.

[AJ113]

Does this valley, where the two hills meet, flow in one direction or t'other? It's hard to imagine a valley that is flat along its long section.

The wall is a nonsense idea, subtrerranean or not. A ditch is a better option but what is really needd is a swale, a ditch that dries up as soon as it's allowed the water to percolate down to the ground beneath. You might need to dig a ditch, say, 1.5-1.8m deep, and then backfill it to, say, -500mm with an 'improved' material, such as a sandy loam, that will allow it to "drain".

There's a bit about swales (and other SUDS technology) on the Suds Intro page.

Thanks for the reply Tony

As far as I have witnessed there is no discernable flow, hence the flooding at the bottom of my garden. I think that the valley may be slightly raised at each end, and that's why there is no flow to the water. In effect, the bottom of my garden is already a 'natural' swale, and I like the idea of improving it to be more effective as you suggested.

Another thought: If I dig down to 1.8 meters to create a more structured swale, presumably I could spread the soil that I've dug over the bottom part of my garden, thus raising the level of it and making it less likely to flood?

[AJ113]

Been thinking about this Tony, the front garden border is 57m long. With loam at around £100 per tonne, isn't this going to cost me about 5 grand just for the loam? (That's UK prices, I don't know what the BG prices are)

[Tony McC]

Don't buy loam - buy grit or grit sand and mix that with the excavated topsoil. You can get a 20 tonne load of class M sand for around 14-16 quid per tonne.