The Big Wet gets even Wetter

2010 is set to be our wettest year for 30 years. Over the weekend we had over 150mm of rain which makes it our wettest October since we started keeping records. Although this has delayed our spring planting for a few days, it has given us many exciting (and sometimes amusing) sights.

Not only are our tanks and dams all overflowing profusely, but every depression in the ground is now full of water and creating little streams of runoff. As our son Greg commented, there seems to be water seeping out of every nook and cranny. Our wheelbarrow gets extensive use shifting all sorts of materials and this weekend we even had barrowfuls of water to shift (but nowhere needed water).



Our jetty nearly went underwater

When we were first looking for a property to purchase, one of our dream criteria was a permanent stream or natural spring. Tenderbreak has finally given us our springs (temporary we think?? ). They are popping up everywhere, as water seepage follows channels below the ground till it eventually comes to the surface. These are feeding our gullies which have turned into small streams, our main gully has turned into a fast flowing creek, Pauls Creek has turned into a raging river (nearly washing out our access road and the Yarra River has turned into an inland sea down at Yarra Glen.



When the dam outlet pipe couldn't cope, the overflow went over the driveway



Now we have a new range of adventure activities on our property.....white water rafting, surfing, canoeing, riding barrels over waterfalls or for the more fearful having “boat” races using leaves, sticks or bark.

All this beautiful water has given us an opportunity to flush water out of the dam. We opened the gate valve on the outlet pipe open for several hours allowing stagnant water sitting at the bottom of the dam to flush out. The fresh, nutrient filled rainwater then topped up the dam. The fish should find this very refreshing.



Releasing water out of the gatevalve



Some more photos that give an idea of the sights that behold us.



Emergency road repairs!



Rapids in Pauls Creek



Horse "float" Parking





Yarra Glen Race Track

Surfs Up as water enters the Yarra River

Pauls Creek is now a river

Making the most of a dam

The last post outlined our solution to water security. Here is a summary of our priorities relating to dam design and list of the many functions dams can fulfil.

Dams are expensive to build so we recommend thinking through the design/layout, reading widely and studying the topography. If you are thinking of building a dam, here is a checklist of our priorities:-
· Place the dam to protect your house from fire (in fire prone areas)
· Engage a reliable contractor who knows what’s required. Cheapest is not necessarily the best
· Evaporation rates are higher in shallow dams. Incorporate enough depth to tide you over an extended dry break.
· Include some shallow areas around the edges for vegetation and habitat for fish, frogs etc.
· Vegetation around and on the water reduces evaporation and helps settle sediment. This can also be harvested from time to time as valuable biomass for composting.
· Use fences to prevent stock from increasing sedimentation and erosion
· Size the dam according to available catchment- it is no use having a dam that never fills
· Build an outlet into the dam wall so that stale water can be released from deeper levels and environmental flows can be made.

A dam is more than just a water supply. Our dam serves at least 10 different functions making it a very worthwhile investment.
1. Water supply for garden and orchard.
2. Permanent water source for fire fighting.
3. Non flammable static fire break.
4. Dam wall provides a gully crossing point for vehicles.
5. Fish for food and recreation.
6. Swimming and boating.
7. It attracts wildlife which in turn helps us. Wild ducks eat snails, and wallabies keep grass around the dam short and leave fertiliser behind.
8. Micro climate effects- increases humidity.


9. Harvested reeds provide biomass material for composting.
10. Provides many aesthetic qualities and provides private areas for meditative experiences.

Incorporating an island in the dam has some disadvantages. It adds to the construction cost, and the island takes up space that could be occupied with water thus reducing the overall capacity of the dam. However it does have its beneficial aspects.

We included an island because it had aesthetic appeal and provided a safe haven for wild ducks and other birds. It adds extra edge to the dam which increases the potential food supply for fish if the dam is stocked. The island also provides a destination when swimming or boating.

Water Security

We all need a reliable source of water, but this is especially critical for farmers and those who are growing food. When we developed our permaculture design for Tenderbreak PF, there were two issues that had the highest priority, and influenced all our decision making - these were water supply and fire defence.

The dam was the first thing we built. It was sited where it would have a good catchment area- at the junction of two natural shallow gullies. During periods of heavy rain we had seen these carry water runoff and knew they would help our dam fill rapidly. The critical words here are “periods of heavy rain”. Unfortunately there can be long gaps between these periods, but when the rain does come, it is a real joy to see small streams flowing into the dam.

We sited our house, outbuildings and drive so that runoff from these is directed to the “house gully” adding to the natural runoff. Of course roof run-off initially goes into our water tanks, but once these are full, the overflow runs into the gully. Another advantage of this design is that moisture levels in the “house gully” are kept higher, improving the microclimate in the vicinity of the house.

The house and other structures are also positioned so that the dam is to the north, forming a static 50m firebreak between our “house envelope” and the thousands of acres of state forest in that direction. The dam is also a reliable water supply for fighting fires if the need should ever arise. Even in the worst of the drought it only dropped around 1m out of its total depth of 7m.The thought of wildfire is not very pleasant, but having a reliable water supply helps.

Having the dam to our north, and all runoff from our developed area flowing to the dam works really well. To make use of that water though, it has to be pumped, and relying on a pump for irrigation and especially for firefighting leaves one vulnerable to mechanical failure. Our solution was to build a small (.5 megalitre) header dam 200m up the hill behind the house. This is the dam we use for day to day watering and with a 30m head is suitable for fire fighting.

This dam has a much smaller catchment and will only fill naturally during good rainfall years. To overcome this we have connected both dams with a 50mm pipe. When the main dam is overflowing in the winter, we can pump up to the header dam to top it up. This system enables us to start each summer with a good supply of water, capable of being fed by gravity to any of our developed areas.

Even though we have a good catchment, the dam still took over 12 months to fill with water. We reckon it was us bulding a dam that caused the drought. Anyway this gave us plenty of time to build a jetty. (Much easier building it in an empty dam than a full one.) The jetty allows access to the water (for watering, boating, fishing or going for a refreshing dip) without stirring up the mud. More on our main dam in the next post.

In the last post I didn't get round to telling why 600 people came to the open day at our place. Sorry about that, but I became distracted by the Tenderbreak Permaculture Farm story and how it came into existance. The story continues with this post, but I promise I will eventually get back to the Open Day.

The two major elements in our permaculture plan were the house design and the construction of a large dam. The previous owners had intended building higher up the slope to maximise their “view” of the surrounding landscape. This would have kept the house away from any suitable site for a dam and made the access driveway very long (and more expensive to maintain). We selected a spot lower down the slope. The dam was positioned 60m to the north of the house site, at the junction of two small gullies which would assist it to fill more rapidly. The dam would offer some protection from wildfire and be a convenient source of water for gardens and fire fighting.

The year we constructed the dam (1995) was unusually wet, causing many delays. Although the site had ideal topography, the subsoils were not ideal. Kevin Jones, our very expert dozer driver had to go quite deep to locate the clay needed to seal the wall. As a consequence, the dam is much deeper than we intended (7m), but since our climate has started getting drier we are very grateful for having the extra water storage capacity.

We played with dozens of different house designs (varying greatly in layout and types of construction). Initially we were intending to build an earth sheltered house using the “Terradome” technique (Interlinked concrete domes). However three main factors changed our mind – the high cost, the need for specialist builders and we were not comfortable with the thought of living inside an almost totally concrete structure.

Eventually we settled on mudbrick construction using the post and beam technique. We drew up plans ourselves, taking care to integrate as many design elements as possible. Over a period of months we gradually changed and refined these so that the final package would best meet our requirements. One day we will do a post on the main features of our house design.

Once we had settled on the concept we sent off our ideas to Rod Sheppard (Earthform Constructions), who we had contracted to assist us with building the frame and roof, and asked him for his comments. After some minor adjustments we asked Rod to draw up the specs, draft the plans, order the timber and list other materials necessary. I took three months off on long service leave (May to July, 1999). Together with Rod, his mate and Heather on weekends; the slab, frame and roof of our house and barn were put up. An advantage of us working on site was that we were able to be involved in making choices as they came up. Building a house is a complex job and very hard for novices to envisage in 3D, from two dimensional plans. As the building took shape we were able to make dozens of modifications and adjustments. Once the frame and roof was up, we basically did the rest ourselves with occasional help from children and friends.

Initially we intended to use timber off the property and our own soil to make mudbricks. Unfortunately these two ideas fell through. Our timber turned out to be unsatisfactory in size and quality, so we chose plantation grown Cypress Macrocarpa for the frame. After making 60 of our own mudbricks, we realized that it would take forever to make the 4000 mudbricks required. So we settled on puddled bricks (made with the help of a tractor) supplied by Barclay Bricks, a local mudbrick company (Hurstbridge).

We sold our previous house in May 2001 which gave us 4 months to get the new house into a liveable state. We moved in, in late August, but still had no external doors, no B.I.R. and no walls on the garage. Since then we have been slowly finishing off the inside of the house and doing what we like to do most of all -developing the food gardens and outside structures. We’ll leave details of building our mudbrick dream house to a later post.