With the plan to complete the new floor in the chapel first and work up from there, we turned our attention to the running the drain from the sewage connection in the middle of the front garden to the chapel. We knew that the level at the bottom of the IC was only just deep enough to achieve the gradient required for the connection to the stacks planned in the chapel. Digging the the trench to it was to reveal why whoever put in that sewer and IC, did not lay it any deeper or in a more direct line to the chapel.
Some hard work with a spade, mattock and tow rope on the van was required to remove a tree stump and roots before the trench could be dug. With the stump out of the way, like digging out the floors in the chapel, to start with the going was quite easy, then as before we hit rock.
Digging the soil away from either side of the limestone crossing our path left a pyramid of rock that was clearly the reason the IC had not been set any deeper or closer to the chapel, with the slab plunging immediately under it. To make the connection we were going to have to break through and remove a ton of rock. With no foundations or wall to worry about, at least we were able to use the electric breaker, but it was still a back breaking few hours.
Continuing the trench in the other direction we had to take it through the garage wall and under its concrete floor. The garage will eventually be demolished so we didn’t have to be too careful, but before we could get through the wall there was more solid rock to remove.With the gradient checked we dug the hole just inside the garage for a shallow IC, where the drain was to branch to serve the downstair toilet and mezzanine ensuite. We filled the trench with 10mm pea shingle to create the 100mm bed and then laid the pipe and shallow IC. Using an optical level we checked the pipe’s 1:65 gradient making some small adjustments to ensure it was spot on. A check with running water confirmed things were flowing in the right direction. Pressing on we cut through the concrete floor and dug the trench up to the chapel wall where it would pass through the foundation and continue to the planned downstairs toilet. More rock to cut!
However with floors dug out the structural engineer had suggested checking the foundations, as except where the rock rose to the surface, the internal walls did not appear to have the same solid foundations as the external walls, so we moved back inside to dig inspection trenches along the walls.