Saturday 20 September 2014

Drainage and "The Rock"

After a number of delays work at last started over the summer on the installing the drainage system that is to run around the house at the bottom of the west, north and east walls. At the same time, in order to complete the drainage run it was necessary to remove a large rock that had slipped down the hillside during last winter's rains to settle itself half buried virtually against the back wall of the house and was thus obstructing the drainage run.

Given the earth sheltered design of the house drainage is an important component since any below surface water running down the hillside will accumulate when it reaches the house and this water needs to be rapidly removed to avoid an excess build up in pressure upon the walls.

The general idea is that this accumulation of water will trickle down through successive layers of filtering i.e. large rocks, small rocks, gravel and finally a cloth like membrane before entering a large drainpipe, perforated on the top half and located at the bottom of the walls, before being stored for watering the lower garden area during the long dry summer months.

The bottom of wall drainpipe drilled and ready for membrane cover and gravel.

Whilst a digger forms a" roadway" adjacent to the western wall the gravel is craned into position.

Applying the gravel at point of need!
Detail showing drainpipe drilled across upper half, cloth menbrane and gravel filters.

(All drainage photos courtesy of Babis)

Part of the delay to progress was the need to leave the concrete walls sufficient time to cure before attempting to move "the rock". Hence the delay until the summer.

Various approaches to breaking up / removing the offending rock were considered including dynamite (NO!!) and cold blasting. In this holes are drilled in the rock  then filled with water, sealed and the water is frozen. The force of the expansion of the water as it turns into ice fractures the rock into smaller more manageable pieces.

However, as a more realistic approach, it was decided to construct suitable digger wide "roadways" on the western side and most of the way around eastern and northern sides which would allow the long arm grab of the digger to reach around the final corner to grab "the rock" and to then slowly and carefully to drag it out.

Simple really!!

"The Rock" within 15cm of northern wall and half buried.
Cutting a "roadway along the northern wall to gain access to "the rock".
Dragging "the rock" out.

Finally "the rock" is exposed in all its glory.

One of the particularly satisfying outcomes of this approach was the way the waterproofing, drainage and excavation teams worked so well as a team to attain the goal.

(All photos exceptfirst and last in "the rock" sequence courtesy of Babis.)