The Retaining Wall

When we moved into our rural abode seven years ago, the place wasn’t in too bad a shape, but there were some things that beggared belief and, to this day, I can’t understand how these things passedĀ  council approval, if they ever did. The veranda was one aspect (which I still haven’t quite finished), but vastly more significant was the retaining wall along our front driveway. Absolutely no building regulations could have been followed with this pretend retaining wall and the fact that there had been no serious accident (as far as I know) prior to us moving in, is amazing. That retaining wall was constructed of 200mm x 50mm treated-pine sleepers with no concrete foundations, but simply a few 200mm x 50mm sleepers pushed into the ground to hold it up, with a horridly narrow dog-leg in the driveway to make things even more dangerous. I was truly fearful that a car would go too close to the edge and roll over into the not too minor drop below. That was the first thing that needed to be repaired and many thanks to Rob from Evison Concreting and Chris from C&D Earthworks for a great job in fixing this abomination (and for letting me observe and learn something new).

Retaining Wall Repair

Retaining Wall Repair

But that wasn’t the only retaining wall that was constructed with no concern for building regulations. The retaining wall that supported the earth embankment next to our carport was constructed inĀ  exactly the same manner and was slowly deteriorating and close to collapse. I have no idea what the results would have been for the carport if the retaining wall had collapsed, but I suspect that it would have resulted in a lot of work and expense to rectify. This was a far less involved repair and with what I learned from the driveway retaining wall, I was well prepared for what was required. This retaining wall was also in a somewhat awkward place, so heavy machinery couldn’t get in and everything had to be done by hand. There was also a lot of tree pruning required just to get in to dig the post holes. Anyway, while the weather reports were promising dry weather for most of the week, I decided that I’d concrete in one 100mm H section post ( for 200mm x 75mm treated pine sleepers) each day. So with a heavy 2m post-hole digging-bar (made by an actual Blacksmith in Newport, Melbourne, many years ago) and a long-handled spade, I got to work. The mornings were freezing this particular week, so I’m kind of glad that I decided to do one post per day, as that meant I’d finish one post each afternoon when things had warmed up.

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Doing one post per day actually worked out quite well, as I wasn’t rushed to finish anything and it gave me the opportunity to think about what I was doing. If you’re doing these things day in day out as a full time job, it becomes second nature and you know what has to be done so you don’t make mistakes. But when you do something like this once in a blue moon, you need to step back and evaluate what you’re doing before moving ahead too quickly. Sometimes it’s just a simple thing that trips you up and, when it comes to concreting, you often don’t get a second chance at getting it right. Given the nature of the ground, if a pile driver could have been used, I don’t think any concrete would have been needed. Thankfully, things worked out reasonably well and the posts went in without any drama and were aligned quite well and yes, the posts are perpendicular (I decided not to lean the posts, given the fairly short distance and low height), they just look off in the photographs. The next thing needed was the placement of the sleepers, normally an easy task, but with the slope of the land, I needed to do some additional work on the sleepers placed at ground level.

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

It was only when I started this repair did I realise how poor a state the retaining wall was really in, with much of it simply rotting or already rotted away. This being between our yard and our neighbours, and usually covered with spreading bushes and trees, I hadn’t given it that much thought until recently and it must have really gone down hill in the last year after a lot of heavy rain, as it wasn’t this bad the last time I looked. Just walking on parts of the surface was worrying as the edge gave way ever so slightly and not so slightly near the driveway, where things were at their worst. The driveway side further on is also in a poor state of repair, but it’s only about 30cm high so no where near a danger. The retaining wall will be extended further up, but this section was the most critical to finish soonest. It simply beggars belief that anyone would do this poor a job and that anyone would accept such a poor outcome.

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Once the concrete was thoroughly set, I laid down the base sleepers to ensure a level starting point for the rest of the sleepers. This basically involved cutting the posts diagonally in two, and levelling off on the ground. In fact I didn’t have to do much work here except for a slight amount of soil removal on the high end, as the slope almost perfectly matched the angle of the cut sleepers. All that was required now was to lay the additional sleepers on top, make sure they were flush with each other and set them in with batten screws. I was tossing up whether to also screw the sleepers to the steel posts, as that’s what was done with the driveway retaining wall. I guess what this does is locks the entire wall into one more or less solid frame so that any movement is minimised and taken up by the entire wall. I also needed an end piece to hold the soil and rock from simply falling out the end. Of course as soon as I was about to start installing the final sleepers, we had non-stop rain for several days that delayed finishing the retaining wall, just when I was full of enthusiasm to get it completed (payback for doing just one post per day I guess).

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

But once all the sleepers were in place and the end secured, it was a simple matter of sorting out the drainage, filling part of the void with crushed rock and then soil on top. And after consulting with quite a few of the local builders, most said that I’d be better off leaving the old timber in place and, as it rotted away, just add fill to take up any voids. It really did make a lot of sense, for if I’d removed the old wall, there was a significant chance of the earth subsiding and causing far more damage than slowly rotting timber. The wall is actually about one sleeper higher than it needed to be, but I wanted a lip of sorts over the ground level so I could nicely level everything off. The crushed rock went in evenly and, with a permeable membrane over that, I could then add top soil to bring things up to the level of the existing ground. I’m going to leave the soil like this for a while so that it can naturally settle and then add more to cover as it settles. After that I’ll think about planting some shade tolerant low growth plants to help bind the soil.

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

Retaining Wall Repair

So overall this was a pretty easy and not overly expensive project, which make me wonder why this wasn’t done properly in the first place. If the existing retaining wall has been in place for around 17 years (utterly incredible), according to my neighbour, then the new one should last many times longer. And, personally, I think this new one looks a lot better as well. I’ll now just have to get the motivation to extend the wall up the driveway so that I can call it ‘job done’.

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