SPA HILL ALLOTMENT SOCIETY LIMITED


The Wind Turbine Project

1 Preparation

Picture site road looking towards allotment centre

We have a 2.5kw wind turbine on an 11 metre mast on the allotment site. Getting it installed was far from easy and almost three years passed between first concept and installation .

We started by looking at all the possible sources of renewable energy available to us. Photo voltaic was ruled out because most of the available roofs sloped the wrong way; we may reconsider it in the future if, when buildings need to be re-roofed, the pitch of them can be realigned. We also looked at biomass fuels and at geothermal energy and may decide to examine these in more detail in the future. The most effective option on our site however appeared to be wind energy.

By this time we had involved Creative Environmental Networks who knew much more about all this than we did but they agreed that we should do best with wind.

The really hard work part, finding grant money to fund the wind turbine, was also largely done for us by CEN. Then we had to get planning permission, CEN gave us a lot of help with the application, we wrote letters to over 600 local residents inviting comment. Then the planning officer visited us. CEN prepared photo mock ups of what the site might look like with the wind turbine installed and we put up a steel pole with a yellow flag on it to give some impression of height and position. We got a few objections and rather more messages of support and finally we got our planning permission.

The next part of the job was digging trenches to bury the ducting through which we would pull the cabling. Easy enough where it ran down grass roads, we could hire an excavator, but where it ran down the narrow paths between plots and between plotholders' sheds we had to hand dig metre deep slots which the volunteers all agree was very hard work. That part of the site had been a brickworks in Victorian times and three feet down we were in the layer of flint and pebble which the brickmakers had removed from the clay to make it useable for brickmaking.

Finally we were ready to actually instal the turbine.

The hole for the foundation

Dig a hole, two and a half metres square and well over a metre deep. Even in a dry summer the bottom rapidly became a sticky quagmire so we dug it a bit deeper and put paving slabs in to give firm suport to the metalwork. Fit reinforcing steel and the huge bolts which anchor the baseplate for the mast into it, then set the base plate on top of them.


Pouring the Concrete

Next pour concrete until the hole is filled to the level of the base plate. It took over six cubic metres of concrete, and manoevering the huge lorries which delivered it on the allotment site required extreme skill from the drivers but only one plot got wheel marks on it.



Tamping and Levelling

The concrete is tamped with a vibrating poker before being levelled with shovels and a scaffold board on edge.



Digging the anchor hole.

A second hole is dug eleven metres away from the base of the mast to hold the anchor for the winch which will be used to pull the mast upright and later to lower and raise it for servicing. This hole takes another metre of concrete.



Next Delivery to the site.