Trench Excavation

It was a big day today. I didn't finish until 5:45 (45minutes after dark). The excavator guy came to do the excavation.


My pier liners are lined up to protect the mains sewer (against nuclear attack)





You can see that the strata changes quite a bit. It goes from white sand to gravel to yellow sand quite quick.



I also sprained my ankle today - oops.

Marking Out Excavation

Today, I marked out the excavation and attempted to verify all the points. They all seem to be within the 5mm accuracy I desire. I used pink marking paint.

The guy dropped the excavator around.

I used the following calculations to determine the points in a cartesian plane. I derived this at the work site using the Pythagorean theorem.

Tree Roots

I took today off - last day in a 4 day stint. I was planing on using today and yesterday for shoring - but that was finished on Saturday. The excavator guys were around again and spent the whole day here. Jim had to go off and do something in the morning so I got Glen to dig out some tree roots - from the 12m pine that was cut down. It was such a struggle that I had to help him with my reciprocal saw and cut some of the roots. Some of the roots had formed a tightly meshed web and this made it even more difficult.

Jim offered to take the roots to the tip for me - he estimated that there were 2 tons of roots. Initially I accepted saying that they were far to big for me. However I reneged and fortunately Glen latter offered to load my ute with the excavator. On the first trip, the Kimbriki guy said that the roots are classified as stumps - expensive, but I said that they were not very thick and that I loaded them myself - which was true - the first load was mostly small stuff. The second trip the guy kept on saying that I should be on the weigh bridge - about three times but not quite condemning me. I said I had another trip and then I would go on the weigh bridge - he was happy with that. That trip I carefully hid a big piece at the bottom ~200kg. I managed to unload it no problem.

The last trip was such a laugh since mostly it was that last huge root mass that stuck out of the ute by about a metre - there was no way anyone was going to let me through for free. Jim wished me luck and asked me whether I wanted a chain to tie the root to something stationary and drive off. He also hoped that there was a friendly excavator guy there to give me a hand. When Glen was placing into the back of the ute - he pushed it around and it was quite funny to see my ute also being pushed forward as well. I was pretty nervous about taking the root myself - what happens if I can't unload it???

I went the the weigh bridge and then off to the dumping area. Fortunately all the attendants were busy in conference. One guy noticed me and asked me if I just wanted a ticket. He gave me one just for veg without even looking at my ute. I struggled a bit to heave the root mass off - inching it along. Eventually I got it over the side and it was resting against the side of the ute. The only was I could tip it over was to use my feet with my hands handing onto the side of the ute with my bum on the tray. They are sure going to love me when they try to mulch this sucker. It would have been almost 4m long 80cm wide and around 40 cm thick. It certainly looked massive. But being pine it was actually quite "light". Off back to the exit weigh bridge to pay. My load weighed 550kg - I estimate the root mass would have been about 400kg of that.

Now I can move the water meter again and put in a request to council to modify the driveway on the verge.

The Excavation Begins

Today turned out better than expected. I was dreading many things going wrong - but they didn't. Things didn't go perfectly - the auger was missing a tooth so the hole was a bit too small for the pier liners.

The guys turned up just before 7am and dutifully waited for the council approved kick off time before starting up the machine.

The guy (Glen) drilled the holes. Before hand I explained about the geology - a weak sandstone seam running about 600mm deep. He gave a knowing nod when he hit it. The 450mm holes were a bit of a problem. Because the auger was missing a tooth, we spent a lot of time reaming them out to fit the liners - we resorted to pushing them down with the excavator with mixed success.




The next stage was the trench. The guy was very careful and did a really good job. I used a laser level to maintain accuracy. He seemed to be able to get it done to the centimeter accuracy.



It was a bit tricky with the west end the trench - Glen had to stradle the two sides of the trench with mixed success. Eventually we resorted to using a few of my salvaged timbers to reduce the pressure on the ground. It still caved in a little bit, but I was happy with the result.



Glen was very dubious about what I was planing, he kept on asking questions like whether I was planing on going into the trench and telling me that he hoped it would not rain soon. However, once I hand auger my first hole and poped a post in, he came over saying that he had to see this and went back to the excavator saying that he was very impressed.

It was about lunch time when they finished so I took up the offer of getting some of the dirt taken away.

Ready for the Excavator

I continued to use the dingo this morning to stockpile fill. I probably didn't stockpile enough, but I think I'm meant to use course gravel (for drainage) anyway. You can just make out the plywood sides I used to contain the pile in the picture. They are supported by hardwood posts buried around a metre deep or so. They seem to work well. However, the plywood bows a bit.

The only problem that I have with the Dingo is that it easily get bogged and with a bucket full of sand, it gets top heavy and has a tendency to fall over forward - the tip of the day is to hang on! Getting it unbogged is a sinch since one can just lower the bucket down and the front wheels are off the ground. If I hire one again (I doubt it), I'll make sure it is a hydraulic 4wd model - not chain! It fits easily onto the back of a aluminum tray ute using a pair of bobcat ramps. After about 8 hours of use, I think I can be considered 'OK' at handling the Dingo. I think I'll try something bigger next.

The skip bin guy picked up the 10cum of soil and dragged it away - not problem. Fortunately, the concrete drive did not crack



It is interesting that I attrack the interest of mums with their young boys. I hope the mums know what I am doing 'cause I'm sure I don't ;)

Dingo

I hired a mini excavator (called a Dingo) today to fill up the bin. It weighs around 900kg so I put it in the back of my truck :) The rental guy was a bit dubious but the the ute is rated to carry 1.4 ton pay load. The ute sure did plunge putting it on and taking it off. After around 4 hours, I can definitely say I am getting better at it. I think I prefer a shovel and wheel barrow though - I don't get bogged. I topple over once and slightly injured myself - I have a huge bruise on my shin.

I started laying out the building today. My datum point is the south west corner. I marked exactly where the piers should be placed.

You won't believe this, but the engineer had called for 600mm diameter 1.8m deep piers to support the roof covered deck. I calculated the rated performance of the pier and it can support 4000 kN and resist 350kN lateral load. It is interesting to note that the post holders are rated at 25kN compression and 45kN tension. Not that I have a problem with over designed foundations, but it is ugly. I rang the engineer ans asked whether it was really necessary for such wide diameter piers. Apparently not - he had designed to to support a two story concrete slab building and told me I can reduce it to 450mm like all of the others.

Preparing for the big excavation

I spent the last couple of days preparing for the big initial excavation. This included digging a shallow trench to indicate where the excavator should go. I got a huge skip bin delivered (10cum) which I have been filling up with soil. I'm thinking about hiring one of those dingos mini-excavators to help me out.