Digging time!

I've just completed two full days excavating and the site is taking shape.

1.7 tonne excavator

1.7 tonne excavator

1.7 tonne excavator

Removing the existing vegetation prior to full excavation.

It's my first time using an excavator and I've learnt two things about them:

  • They are - unsurprisingly given the name - excellent at excavating.
  • They are extremely poor at moving dirt around.

I believe that this type of work would typically use both an excavator and some sort of dirt mover like a bobcat or dozer. The excavator digs, the dozer/bobcat moves the dirt where it needs to go (typically a dump truck for removal from the site).

If you're ever excavating, but time is an issue and you have the people/resources, I'd definitely recommend going with the two-person/vehicle solution. I estimate a full 40% of my time was spent simply moving dirt from the excavation to site to a location further down the yard where we plan to build a retaining wall to create a more level grassed area. The other 60% of the time was about evenly split between excavating the site and repairing pipes that I broke.

Avoiding an emergency

Before beginning the excavation, we contacted the local authorities to determine if any underground services existed on the property and where they were located. We received replies from the local telecommunications, electricity, and gas companies as well as from the local council regarding underground storm-water assets.

The responses indicated there were no public assets close to the excavation site, but the location of the public storm-water pipes at the downhill end of the property made it quite possible that the storm-water overflow ran directly through the planned site.

The residence has an existing 13,500 liter rainwater tank, with all roof gutters draining into the tank. The tank has an overflow, and given the location of the public storm water pipes, we expected to probably hit that pipe during the excavation. That's not a big issue as the pipe has no water flowing through it unless the rain water tank is full and it's raining. Since we emptied the tank prior to excavating (the excavation comes close to the tank slab and so we wanted to minimize the tank weight for safety), that wouldn't be possible.

Oops

Nothing quite describes the sense of urgency engendered by the high pitched cracking of PVC pipe and a six foot high stream of water shooting in the air. The first pipe hit turned out to be a storm water pipe traversing the edge of the site from the gutter down pipes on one side of the house to the rain water tank. Water empties into the tank at around the two meter level, and so the pipe from the gutter was like a big U and full of water.

Most of the water drained out relatively quickly, but a steady stream remained as the water from all of the down pipes drained. Having only 90mm pipe on hand to fix a 100mm pipe, we hastily cut a semi-circular section of 90mm pipe, covered it in silicon and cable tied it to the bottom half of the pipe to contain the water, which only filled around 30% of the pipe.

Broken pipe

A very temporary repair

A semi-permanent (until a plumber can effect a permanent repair) followed once we'd had a chance to fetch the appropriate supplies.

Broken pipe

A less temporary repair
More water! Not the good kind :(

The second pipe I hit was passing across and just above the final level of the pool deck. Unlike the previous pipe, this one wasn't storm water, and instead transported altogether more feculent contents.

Thankfully noone happened to be in the bathroom at the time and my excavator bucket was only greeted with a steady stream of soapy suds as the washing machine emptied it's load. Another hasty repair followed and we were eventually back in business.

This is what the site looks like after two days of digging:

Site after two days of excavating

Two days of excavating

The basic shape is set, but there's plenty to be done to dig the trenches for the retaining wall footings, leveling of the pool deck (that pink line halfway up the photo), and digging the shape of the pool base.