attenuation pond

In Case The Flood Comes

Our small and ancient town of Much Wenlock sits in a hollow beneath Wenlock Edge. The Edge itself is an uptilted Silurian seabed, formed some 400 million years ago, and the farm fields around the town rise steeply to the Edge top. In consequence, flash flooding has long been a problem and in recent years (after the 2007 storms when the town centre was badly inundated) our locality has been designated a rapid response flood risk zone, the danger coming mostly from field run-off feeding onto roads and lanes that run into the town.

And so finally in 2017, after much humming and ha-ing, the Local Authority commissioned engineers to excavate two flood attenuation ponds at either end of the town. They are basically reverse reservoirs in that they remain empty with the aim of catching up the worst of any flood should a particularly bad rainstorm hit the Edge.

One of the ponds is at the top of Townsend Meadow, behind our house, and given the upward slope of the field, I found myself much taken with the sight of the big digger and dumper on my horizon as the work was underway. I think I’m also happy to have the pond above our house, although the Farrell domain did not flood in 2007, and some experts have equivocal views about the utility of attenuation ponds in rapid-run-off situations. Anyway, so far so good. Besides which, the guerrilla garden behind the garden fence is on a small rise and forms something of bund to protect us.

Now for more digger views, far and near:

Cee’s Black & White Photo Challenge: Busy with purpose

From The Side-lines ~ Digging Not Flooding

Our cottage is rather short, the upstairs rooms being contained mostly by open roof space rather than walls. Also, the house itself is set in the side of a steep bank between Townsend Meadow and the main road, which means the best views (our only good ones) are from the bedroom roof-lights. These windows all face west and overlook the field towards Wenlock Edge and the big sky above.

Much time can pass at these windows, studying cloud movements or the wheeling of rooks and jackdaws. Sometimes the odd soul (with or without companionable dog) walks by on the field path just beyond our garden gate, and sometimes on Monday mornings, the town’s entire ‘walk for health’ mob, several dozen strong with high-vis vested leaders and bringers-up of rear, trails by. Now and then, too, the farmer can also be spotted, driving his latest substance-spraying rig back and forth across the crop (this week it was a top-dressing of fertiliser for the wheat which – after the rain – is already shooting up like multiples of Jack’s beanstalk). So given this general lack of activity out back, the appearance of a big digger and very large dump truck on the near horizon was an exciting event.

The work in progress (over the brow of the hill and out of sight in the field’s top corner) is the excavation of an attenuation pond. (There is another larger one to the south of the town). They are basically reservoir basins, but without water – designed to stem the impact of any flash flood off Wenlock Edge. The town sits in a bowl between the Edge and several hills, and has been designated a rapid response flood zone. This sounds alarming, and indeed could well be, but the conditions for flash flooding are very particular: i.e. if a severe storm hits our catchment after prolonged periods of rain when the ground is sodden, or in winter after hard frost. Water that cannot drain into the land flows into adjacent roads which then act like rivers, speedily conducting the run-off into the town centre. This can all happen in the space of 20 minutes.

As far as we know, and despite its shortness and low-lying position, our house has no history of being flooded. In the last big flood of 2007 the water seemed to flow around us. I watched the rain pour off the garden terraces behind the house, flow by the kitchen door in a fast running stream before emptying on to the main road where it doubtless contributed to the flooding of properties downstream of us.

It was unnerving to see, and later we heard that at least 50 houses in the centre of town had their cellars and ground floors deluged. That evening, coming home from work across the Edge, Graham had to abandon the car on the far side of town and take an upland ‘cross-country’ route home.

How well the ponds will serve us is yet to be demonstrated. After 12 years without a flood, it is easy to imagine that it won’t happen again, though last month The Man from the Environment Agency did come specially to town to tell us we must remain vigilant. As many round the world know to their cost, climate change is responsible for an increase in extreme weather events and, in the most extreme scenario, our ponds will only slow the flow, not stop it. There are probably further measures that could be taken: urging (enforcing would be better) landowners to plant more trees, create more flood plains round water courses, stop selling their land for large housing developments whose roofs and access roads accelerate run-off.

For now, though, all thanks are due to the workforce who toiled, excavating and landscaping the ponds, which may one day save our most vulnerable residents the distress of having to spend a year and more drying out a flooded home. In the meantime, I keep watching the sky over Wenlock Edge. At times when the rain closes in, day after day without let up, it’s easy to wonder: is this flooding rain?

Cee’s Black & White Photo Challenge: from the side

From My Window ~ Black & White Sunday

According to the old tithe maps the field behind our house was known as Townsend Meadow, and for obvious reasons: it lies on the north end of town directly below Wenlock Edge. For nearly a year now Shropshire Council has been building a large attenuation pond just over the brow of this hill. The objective is to reduce the effect of flash flooding, holding back storm water that runs off surrounding hills, turns all the roads and brooks into rivers which then converge in the centre of Much Wenlock.

In July 2007, over fifty houses in the town were badly flooded. Ours was fortunate not to be one of them; although our house is built into the foot of this hill, the main burden of run off flows around rather than through our property.

The fence in this photo was the first thing to go up before work on the pond began. The tree that appears to be in the corner is a piece of ‘borrowed landscape’ and is actually some distance away in the field hedgerow. And the rooks were just passing.

Before the fence went up I did not particularly notice the tree, but now I like the way this visual convergence gives an accent to what before was a rather featureless wheat field.

It was even more exciting when the big digger moved in.

Black & White Sunday This week Paula’s challenge is STRUCTURE

The Big Digger Driver And The Kindness Of Strangers

I think I’ve mentioned that here in Much Wenlock we’re in the throes of having a couple of attenuation ponds dug above the town – this in a bid to reduce flood risk. We are in what the Environment Agency calls a ‘Rapid Response Catchment Area’. This means that if a severe storm hits our part of Wenlock Edge, then we have about twenty minutes warning before a flash flood reaches the town. There are other factors involved too. Flash flooding is more likely if the ground is already sodden from periods of prolonged rainfall. Or if it is frozen hard.

Our last bad flood was in the summer of 2007 when over fifty homes were affected. Due to the steepness of our catchment, any flood is usually quick to leave, but even so, it can cause a lot of damage.

One of the attenuation ponds, currently nearing completion, is in the top corner of Townsend Meadow behind our house. Earlier in the year, and in preparation for the excavation work, a number of small trees were felled and shredded into heaps around the pond perimeter. Yippee, I thought on discovering them by the path on the long way round to the allotment. More chippings for paths and weed suppression.

I duly went to collect a few bags full, but it was harder work than I expected. For one thing there is quite a haul up the path from the pond, and then once at the top of the hill and into the wood, another haul down the field boundary to the allotment.

Meanwhile, my chippings collecting habit had not gone unnoticed. Late one afternoon in April, and after the working day was over, I was plodding up the path with a full bag when a truck pulled up on the field track that the construction crew were using. It was the digger driver in the photo. A very Welsh digger driver. At first I didn’t quite grasp what he was saying. I thought he’d come to tell me off. But that wasn’t it.

When I explained what I was doing and where I was going with the chippings, he said it would be no problem for him to move the chippings piles to the top of the hill. In fact I think he would have delivered them to the allotment if there had been suitable access. He drove off down the track, and I carried on with my bag, and rather forgot about the digger man.

Sometime later (I was pottering around in my polytunnel) fellow allotmenteer, Dave, came to tell me that he had been surprisingly hallooed from the neighbouring field by a very Welsh man who was going on about chippings and some woman he’d met on the path. After some thought, Dave had concluded I was the woman in question, and so we went up the field to investigate, and there at the top of the track was a huge pile of wood chips – enough for all my paths, and more to compost over the winter. There was no sign of the digger man. I expect he’d gone home for his tea, but Dave helped me fill my big blue IKEA bags and carry them back to the plot.

So lucky me! Two very kind men in one day. And a nice new path between the polytunnel raised beds, which incidentally were made by a third kind man who lives in my house.

Black & White Sunday: After and Before This week Paula asks us to give a colour shot a monochrome edit.

Tish Farrell

Writer on the Edge