preparing a site for installation of high pressured system

The ditch witch digging a trench for the irrigation pipe to lay down in.

Laying pipe down in a bed of sand. Wiring being taped underneath to prevent damage if pipe needs to be excavated.

Back filling with sand and then the excavated soil.

A schematic diagram of the circuit.

Positioning the solenoids to be connected to the control box at a later date.

Trench for a line along the production beds.

marking out the site for solenoid boxes.

isolating and marking out trenches and excavated holes to prevent injury, redirecting traffic along safer routes, restricting general public from entering work site.

Paving Job at Arthur Circus

Over two days I helped pave a council path at Arthur Circus in Battery Point. This was paid casual work for Botanic Resources.

The existing sandstone pavers were deemed a safety issue for pedestrians given that they were old, cracked, uneven and slippery when wet. These existing pavers were broken up into smaller pieces with a jackhammer and were collected as landfill for another of Botanic Resource's clients. Some of the larger pieces were set aside for other landscaping jobs.

Once all the rubble was collected, the path was excavated to a depth to accomodate the layers needed under the paving (FCR and coarse sand) and to allow the pavers to be slightly above ground level at all points to prevent water pooling on them. Drainage needs to be adequate and usually it is recommended to have a slope or fall away from structures of about 1cm per metre. Stakes with string lines can be useful to ensure there is the correct fall.

The base is laid with FCR and then compacted with a plate compactor.

Prior to operating, it is important to check fuel tank is full, engine oil is at correct level, that there are no loose nuts, bolts or screws, ensure that there are no foreign objects buried shallow in the FCR. Whilst operating this piece of machinery it is important to use protective eye wear and ear muffs, steel cap boots, gloves and full sleeve shirt and long pants. Use two hands to operate compactor and ensure hands, feet and loose clothing are kept clear from moving parts of compactor. Ensure the work area is clear of any obstacles.

It is essential that the base is well-compacted and so the process is repeated until the correct depth is achieved (take measurements from string lines to base). Laying the FCR base outside the boundaries of the project will make it more stable.

Next, a layer of sand is put down. The sand is the glue that holds the pavers in place. The sand is screed smooth to a uniform depth.

Conduit laid down can help to work to desired level and help to screed sand in small sections.

The pipes can be removed, filled in with sand and leveled with a hand held tamper.

The pavers are ready to lay. These pavers were quite heavy and it was important to lift them by bending knees and not taking any strain into back. Each new paver was held at an angle against the edge of a laid paver and gently allowed to slide into place.

Pavers are cut to fit the edges.

The plate compactor may be used again to tamp the paver into the sand. More coarse sand or slightly finer sand can be swept into the joints to lock the pavers. For added durability and lower maintenance, a sealing product can be used, which will keep the sand between the joints in place and help prevent weed growth. A concrete toe is used to hold the two edges of the path together as a restraint.

During the excavation process, one of the lines of the subsurface irrigation system was punctured. A hole was dug to expose the damaged polyethylene (poly) pipe. Items needed for a basic repair are new fittings and/or heads, clamps, a pipe cutter (in this case a hand saw), pliers. Insert fittings tend to make a better connection and in some cases they are the only option for the site because of all the different sizes of poly pipe and configurations that they are available in.

Clear space around all sides of the damaged poly pipe and ensure no rocks or dirt enter the lines. The new fitting is held up to the damaged pipe to measure how much pipe needs to be removed. When bending the pipe to attach the fittings, be careful not to kink the pipe by bending it too much which will significantly reduce its integrity.

Preparing a site for planting in a larger scale production garden

During this practical session on April 30th, we worked in groups to prepare an area for autumn-winter planting of brassicas for the organic students at TAFE.

The soil in these areas are clay-based, (on feel somewhere between a sandy clay loam to a clay loam) and quite sodic.

Consequently, surfaces collapse easily during rain or irrigation, with the collapsed materials forming a dense surface crust. This impedes infiltration of water into the soil profile and inhibits emergence of seedlings. It can also influence drainage and removal of excess water from the profile as well as limiting the supply of oxygen to subsurface root systems and beneficial microorganisms.

The soil breaks into large clods which make for a very rough seedbed. Ideally, soil aggregates should be between 0.2 - 3mm in diameter.

Improving the structure of such a clay soil involves :

1. the addition of gypsum (Calcium sulphate) given that the soil is dispersive

2.addition of plenty of organic matter

3.judicious cultivation to break up hard and compacted ground (ie. only when soil conditions are right - not too wet and not too dry).

Dolomite (Calcium carbonate/Magnesium Carbonate) was added to raise pH of these areas.

In smaller garden beds, the double digging technique is a good way of mechanically relieving compaction, crusting in the top soil or hardpanning in the subsoil. For larger scale production areas such as the one in TAFE this is not necessarily practical. In this case, a rotary tiller and larger agricultural rotary tiller was used as shown below :

As always, there are benefits and disadvantages of using these machines.

Buried weed seed is brought up to the surface enabling them to germinate. Rotary tillers also can create a compacted layer at the base of the tilled soil. Aggregates in the tilled soil become pulverised. The organic matter that binds aggregates are exposed to attack by microbes. This is why repeated cultivation can steadily destroy a soil's structure. Mechanical tillage like this should only be done once and lightly - once a year probably at most, but with the maintenance of high levels of organic matter.

P.P.E. used during the operation of these machines includes eyewear, gloves, full sleeve shirt and long trousers, steel cap boots, ear muffs.

The smaller rotary tillers are propelled forward by the rotating tines and do not have powered wheels, although they may have small transport control wheels. An adjustable tine acts as a brake, slowing the forward moving machine due to friction as it passes through the deeper untilled soil. The operator can adjust the amount of friction/braking by raising and lowering the handlebars of the tiller. These machine can be pulled backwards or put in reverse to move over areas again, but care should be taken so that the operator does not stumble and pull the machine over himself. Both these machines had gear boxes to allow the forward speed to be adjusted whilst the rotation of the tines stays constant. The larger agricultural tiller has a dead man switch which when released stops the machine from moving forwards or in reverse. Unseen sub-surface objects, such as stones or buried garbage, are also potential hazards as they can abruptly and violently move in any direction.

The benefits of using these machines include efficiency and coverage of a large area, improving drainage and aeration which reduce potential for plant stress and the potential for pathogens.

Reference : Kevin Handreck, Gardening Down Under

Wikipedia - Rotary Tillers

Using the mulcher

Activity : 

During the work practical on the TAFE campus I worked in a group of three people to feed pruned branches of allocasuarinas removed from garden beds through a mulcher. Pre-safety check of machine included checking fuel, oil and air filter and removing any stuck debris prior to starting. One person collected cuttings of similar size, bundled them and handed them to the other person who was feeding them into the funnel of the mulcher. A good tip was to never use a pair of sequateurs near the inlet as they could drop into the mulcher. The third person was on the other end, sweeping the mulch away and collecting it into a wheelbarrow. We found that we needed to feed the pile a second time to get a good sized mulch. The machine was washed down after a couple hours after it had cooled down properly. 

OH&S issues : 

Eye injury from flying wooden debris, dropping hand tools into mulcher damaging the tool and the machine blades, hearing damage from exposure to loud noise all highly likely to occur and of high potential impact. Other issues include exposure to dust and sun. 

P.P.E. used : 

To address these risks, we were required to wear protective goggles, helmets fitted with mesh masks and ear muffs, as well as gauntlets to protect hands and arms during handling and feeding of the prunings and cuttings. We also wore full sleeve shirts and long pants with steel cap boots and high visibility vests. 

Environmental Practises : 

This was a reasonable way of recycling green waste back to the garden although it does require the burning of fossil fuels. The machine we used was inefficient and created alot of noise pollution.