Week 1 – London Clay
Welcome to our first weekly progress report from the site of our eco project. After our first full week on site we find ourselves surrounded by London Clay!
The couple of half weeks prior to this were taken up with site clearance. We needed to begin by removing what was on the plot – an old garage, a couple of concrete slabs and a lot of overgrown bramble bushes. We also found a huge tree stump just below the ground which took some shifting!
The next stage of the groundworks was the digging out of the site. As our plot is on a very slight slope running from right to left we needed to remove quite a substantial amount of soil from the right hand side of the site, to bring it level. We are now over a metre below the bottom of the fence on the right. The soil has been taken for recycling and reuse and we receive full documentation of where this goes and its future use.
When we received our sub soil analysis report it confirmed our extensive clay soil base and that a proposed soakaway on site, to deal with surface water runoff (instead of diverting it to stormwater drains) would not work. We did not fully appreciate what this really meant until we got below the ground.
You can see the clay clearly from these pictures of the trenches dug for the foundations. This would be a potters dream!
Given all the rain we have had in the prior month it is taking the guys on site a lot longer to get things done than normal as everyone ends up carrying a couple of kilograms of clay around on the bottom of their boots, combined with the need to prize your wellies out of clay with every step!
The building inspector informed us that this area is well known for sitting on an area of heavy clay and this was some of the worst conditions he had seen – a challenging start all round!
Despite all of this we have managed to pour ½ the foundations. Additional depth down to 1.2m deep for our foundations was requested by the building inspector which we needed to comply with. Deep concrete foundations were our only allowable option in these kinds of conditions.
The guys have all done really well, considering the conditions, to keep things moving. One of them had an incident whilst carefully manoeuvreing a wheelbarrow of concrete down the ramp into the site and through the clay. As he had a little momentum from this he had to go with it to help him through the clay to his final destination only to arrive and look down to see his feet in the clay only covered by his socks! Looking behind and to his disappointment his wellies were still halfway back across the site standing proudly as if waiting for him to put them on. I won’t repeat the words that were then said…
The other challenge which has presented itself is the complexity that such a small site brings. As a reminder our plot is just 125 square metres. There is not much room to manoeuvre and as we are building right up against each boundary we have also then had to support the fences on each side and hold back the soil on the right to prevent it from falling in.
I can almost picture Kevin McCloud standing there telling us (as if we needed to know) about how all the unknowns are in the ground and that our budget is already being spent before we are ‘out of the ground’ etc. etc. Some of the initial groundwork costs will come in higher than expected but so far not substantially more.
Our schedule is potentially a week behind and the building inspector has just asked us to delay the pouring of the rest of our foundations as the temperature is forecast to not rise higher than 2 degrees in the coming days and he therefore has concerns as to whether the concrete will set and therefore compromise the foundations.
I get the impression the guys will be happy when we get the slab down and they don’t have to spend so much time in the clay but we may have a couple of weeks of that ahead of just yet.