House slab update

3 05 2017

Nico has left. Boy, I will miss him…..  Since pouring the footing for the retaining wall, he and I quickly laid out the drainage behind the footing, and not a moment too early, because over the past couple of days, we’ve had 15mm of rain, turning the

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Sloping gravel ramp

entire site into a quagmire which will put an end to more work for at least two days. Or however long it takes to dry out. I was hoping to cut the last lot of trenches this coming weekend, but that simply won’t happen now……

The drain has to have a 1 in 100 fall to work effectively, so the first thing we did was, after removing the formwork, mark out this slope on the new concrete…. which was smoother than the proverbial baby’s bum, a testament to the effectiveness of the concrete vibrator. It looked like polished concrete!

The drain being 300mm deep, and the pipe 100mm in diameter, I decided to install the top of the pipe at the pointy end of the back of the building at basically footing level, while having it at the bottom of the drain at the other end, 20m away…. an exact 1:100 slope.

The way the drain works is that as water falls into it, the water level rises up through the gravel until it reaches the perforated pipe, filling it up. The water then follows the path of least resistance, which is down the pipe. The ‘sock’ around the pipe filters out any silt that may dissolve from the clay, stopping it from entering the pipe and clogging it. In theory it works, and I have to say I have seen it work in real life in Cooran where I did something similar, though not as high……

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Nico backfilling the drain

The drain was then filled at that slope with 20mm gravel to the marks laid on the concrete every 2.5m, and voila, one accurate slope all made ready for the drain pipes.

The engineer’s drawings call for one pipe, but having seen how much water can come down that slope, I went for two. $200 is cheap insurance, the last thing I want is water in the house!

Once the pipes were laid out, the rest of the trench was backfilled with more gravel – 5 tons of it, all unloaded from the utes by hand -, entirely covering the pipes. More hard work and expense that will totally disappear, never to be seen ever again…. and speaking of utes, they have really been earning their keep lately, with both of them simultaneously loaded with one and a quarter tons of gravel…

Having done this, we then went about on the following day – when the darn rain started – leveling the corner cleanout blocks that will be the formwork for the rear of the slab. This is critical work to ensure the slab turns out dead level. It took us half a day with rain interruptions to lay just six blocks (with waterproofing added to the mortar), but I now have cemented in starter blocks that I can use to string out the rest of them, and that shouldn’t take me more than a day if I can get Caleb back to help me mix mud. The levels were achieved using age old technology in the form of a water level, the design of which I got from Geoff Capper, an old peaknik friend who lives in Northern Tassie. It worked a treat, and even Nico who had never seen one before was impressed.

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At left, Nico leveling what is literally the foundation stone, the highest point on the footing. At right using the water level to ensure that block at the opposite end of the 20170501_143507house is at exactly the same height as the first. The front of the house will be on the visible stringline, and 200mm higher than the footing lifting the whole house about ground level.

We would have laid more blocks, but the rain renders that Dolerite clay into gloop that persistently sticks to your boots making just walking around really unpleasant and even difficult….. in any case, it’s not recommended to either mix or lay mortar in the rain.

We did however spend time between showers cleaning up left over concrete and gravel off the mud in an attempt to alleviate the piercing of the plastic membrane that will be eventually laid down under the slab, weather permitting. And I really want to get this done before the real rainy season starts in the next couple of weeks or so……. I just hope I’m not too late already!

Glenda also wants to rearrange the bathroom layout, and that has to be all finalised so we can pour over the underslab plumbing, which once done cannot be undone!





Mark Cochrane on the Indonesian fires catastrophe…..

11 11 2015

Mark Cochrane

Mark Cochrane

I have finally escaped the endless haze of Indonesia for the moment. The last of my non-Indonesian team should have flown out this morning, but that still leaves the Indonesian people who have endured much more of this than anyone to continue to stew in the smoke. The rains have begun to return so the air is much clearer but worsens each afternoon and becomes serous if a day or two without rain passes.

This isn’t some ancient process started in the mists of time, this disaster began in 1996 with a misguided attempt to drain 1 million hectares of peat lands to grow rice of all things (Mega-Rice Project, overview). This calamity was made ever worse when the El Nino-spawned droughts of 1997-98 set the land aflame, initiating the now annual haze events that plague Southeast Asia. What most people do not appreciate is that once the land was drained the carbon loss process was set in place, regardless of whether the fires happen. Once drained the peat begins to be broken down by microbes and the peat subsides as CO2 is released to the atmosphere. When the fires occur they simply speed up the ongoing process, shifting the emissions to be more heavily weighted on carbon monoxide and methane. They also produce the toxic haze of particulates that blanket the region. For months no one ever saw the sun and shadows ceased to exist. The world was a luminescent ball of smoke during the daylight hours with no idea of the time of day. Usually it was white but on truly horrific days when the smoke layer was particularly thick the world was a sickly yellow in color.

The Mega Rice Project (MRP) is now long abandoned but the oil palm plantations have since taken over much of the peat lands across Indonesia furthering the country’s desire to supplant Malaysia as the leading global producer of palm oil. They’ve succeeded but now everyone is paying the price. The ex-MRP put in >4,000km of drainage canals in Central Kalimantan (Indonesian Borneo) but over in Riau Province on Sumatra where I was in August the palm plantations have installed more than 22,000 km of canals to drain the peat. Out in Papua the oil palm developments are proceeding rapidly as well. Given the internal and international upheaval caused by this year’s fires, there is a desire to somehow ‘fix’ the situation with cloud seeding, air tankers dropping water, and thousands of troops in the field to fight the fires but the reality is that such measures have little effect. Now…

respiratory diseases rise

• Indonesia’s ministry of higher education is attempting to create a research consortium on disaster management.
• Data from Indonesia’s disaster management agency showed the number of people diagnosed with acute respiratory infection increased to 556,945 by November 6.
• After a limited cabinet meeting on Wednesday to discuss peat management, Jokowi said he wanted the research department of Yogyakarta’s University of Gadjah Mada to play a central role in proposing Indonesia’s new peat strategy.

Air quality in Singapore threatened to seep into unhealthy levels again on Friday as Indonesian President Joko “Jokowi” Widodo instructed ministers to form a specialist haze task force to stave off another wildfire disaster next year.

“Do not let the dry season come around next year with us not having done anything,” Jokowi said.

No one wants to face the real issues of what must be done to truly stop this dynamic. If they want the fires to stop then the people will have to leave the peatlands (unlikely) or learn to live without fire as a major land use tool (doubtful). If there is truly a desire to stop carbon loss from these ancient peat forest lands then the drainage canals must be blocked (not easy or cheap) and the hydrology of the region restored, flooding the lands and the newly established palm oil plantations (economically disastrous). In short, the actions necessary to try to mitigate this disaster will be politically untenable unless there is some offsetting gain that can support relocating growing populations and replace the oil palm economy.

The worst part of this sad tale, which is also unappreciated is that the oil palm boom is going to be a short one before the bust comes on these peat soils. The peat must be drained and in many cases burned to create the conditions to allow the oil palm to grow, however once this is done the land continues to sink and erode. Every year the surface of the land will be lower and more susceptible to flooding. At best they will get one or two 20 year crop cycles in before the lands need to be abandoned. The combination of falling land levels and rising sea levels will destroy the peatlands and land uses they currently support. It is another short term strip mining operation that will yield nothing but profits for a few and another ecological disaster for the world.