This will all make a lot more sense if you’ve read part 1 of this article. But anyway, to cut a long story short, it is about designing a PC demo site and training centre in a little market town called Bonosha, in the south Ethiopian ethnic zone of Hadiya. This is to be the nerve centre of a network of solar-powered community-serving water, WASH and Permaculture projects spanning the surrounding countryside of Shashogo Woreda, like a spiders-web of eco-powered basic living amenities that neither the government nor the private sector have been able to provide for the rural population. I presented a brief history of the organisation, this project and its place in that history in Part 1, as well as the site survey information for the project site. Now we will go over the site design.
Elements in the Design
Through consultation with the SMART Permaculture team we decided to include the following elements in the design:
• Vegetables: salad , lettuce , carrot, onion, sweet paper, hot paper, white cabbage, sweet potato, irish potato, tomato (all to be planted into raised and/or double-dug beds)
• Trees and prennials: Moringa, avocado, guava, mango, orange, cai apple (fence and wind break), passion-fruit, Leucaena, Acacia siligna, Napier grass (fodder and visual barrier), sugar cane.
• Chickens, sheep, cow, worm-farm
[Note: CIS = corrugated iron sheet]
Tools and Technologies
The list of tools and equipment is too long to include here.
• International Permaculture courses and workshops
• International water and energy technology training workshops
• Local community workshops and experience sharing
– Food preparation and preservation
– Small scale agri-business model development
• Regional product sales venue for the SMART projects network
Features of Element in the Design
The training facility design includes the following features:
• The style reflects local traditional architecture practices while incorporating both modern and low embodied energy eco-building techniques.
• It includes a training room with seating and desk space for 12 students, a white board and a table for the teacher to use.
• It provides as adequately lit, well aerated teaching/learning space.
• It provides study space for teachers to use in preparing classes, and for students to use in additional study outside class time.
• It provides secure storage space for stationary, reference materials and teaching equipment.
The floor plan and section-elevation diagrams of the training facility are show below. The building is modelled on a local style rural home. It is circular, 8m internal diameter and 7m high. The foundation will comprise a circular strip foundation of stone-cement to 50cm depth which is filled in with hard-core and surfaced with concrete slab of 15cm thickness. Due to the stable clay soil type there is no need to use re-enforcement bar in the slab foundation.
Eight structural columns (re-enforced concrete) of 2m height will be placed at regular intervals (of 45o angle) around the circumference of the strip foundation, which will act to support the roof of the building. Additional wooden columns are set into the foundation in between these at regular intervals (of 1m) around the circumference of the main training area (although these will have a mainly aesthetic function).
The cone shaped roof is supported at the centre by a wooded column of 7m length. The base of this column is sent into a section of concrete 70cm deep, which should completely surround the base of the column to prevent entry by termites into the wood at the base. The roof will be constructed using Eucalyptus pole and natural fibres, done by skilled local house-builders, and it will be thatched over with grass (sindado).
The wall material between the columns will be filled in with cob (clay brick). To make these bricks the construction team needs to conduct some trials with local earth to see which mixture performs best. The clay soil in the top 20cm of the area around bonosha, known as “bulla afer” soil is good quality clay which can be used in construction. Cob should ideally be a mix of 70% clay and 30% sand with fibre (t’eff straw is best) chopped to 20cm length mixed into it. If this soil already has sand in it mixing additional sand into it may be unnecessary. Addition of gypsum may also help to stabilize the soil further. Hence some trials using different mixes of sand, clay and gypsum would be a good idea to see which mix performs best. Cob bricks can be laid directly onto a concrete or stone foundation. The photos to the right show construction of a small cob building onto a concrete slab foundation during an internship program in Konso.
The entrance to the building leads into the training room at the opposite side from the study. The door is a double door 2m across (total). From this room a single 1m door leads into the study room at the right hand side. From this a single door leads into the storage room. The work desks and chairs in the training room are recommended to be custom built from local timber. The study and store room should be fitted with shelves to store stationary, books and training materials such as a projector.
Around the training room part of the facility the cob wall will only extend up to 1m high, leaving a space open for aeration and light to enter the room. However around the study and store rooms the wall will extend up to 2m high. Two windows are set into the wall of the study room to allow light in. The internal partitions between the training room, study and store are made of cob brick and also extend to 2m height. All cob surfaces can be finished with lime-plaster, and painted with natural dyes mixed in a dilute emulsion of wood glue. Exterior walls can be painted in local cultural patterns with this technique.
Placement and Relationships
The training facility has been located in the NW quarter of the site. It is near to the trainees’ composting toilets, for convenience of use during/between training sessions. The CT system (see later section) feeds a grey water absorption trench which “fertigates” (fertilizes + irrigates) a row of fruit trees along the pathway ringing around the training facility. This thus contributes to providing a cool, shaded and sheltered microclimate around the class-room which is ideal for studying. Note also the presence of a barrier hedge, located on the edge of the pathway to the west of the training facility. This screens the western side of the class room from view by people passing on the roadway to the west of the site. There are also barrier hedges along the entire N and S boundaries. Local people often gather to stare at foreigners in this area, so it is essential that a discreet study environment is created so that international students are not disturbed by this. The barrier hedges should be planted as soon as possible using fast growing, tall and dense vegetation such as Napier (“Elephant”) Grass (Pennisetum purpureum) which can also be harvested periodically for animal fodder.
The guest accommodation facility design includes the following features:
• Like the training room its style reflects local traditional architecture as well as synthesizing it with both modern and low embodied energy eco-building techniques.
• It includes accommodation for up to twelve guests (intended for trainees) sleeping two to a room.
• It provides a comfortable living environment, warm at night, cool in the daytime, quiet, comfortable and with adequate space.
• It includes washing facilities, comprising a hand basin and shower for each room.
• It provides adequate space for storage of clothes and guests materials.
The floor plan and section-elevation diagrams of the guest accommodation facility are shown in Figure 2 below. As with the training centre, it is modelled on a local-style rural home, circular, 8m across and 7m high. The foundations follow the same form, with eight structural columns (re-enforced concrete) of 2m height placed at regular intervals (of 45o angle) around the circumference to support the roof. However wooden columns will not be added into the walls and the whole circumference of the building will be walled up to 2m using cob brick, except where doors and windows are placed.
The roof apex is supported by a central wooden column of 7m length as, its base set in concrete. The base of this column is sent into a section of concrete 70cm deep. The roof is Eucalyptus pole thatched with grass (“sindado”).
The building will be internally divided by 6 partitions running radially from the central pole out to the exterior wall at regular intervals of 60o angle. Each partition will form one bedroom and have its own door and window facing out to the exterior. Each room will also have a shower cubicle with hand basin set into the pointed end of the wedge shaped room, nearest to the building’s central column. The shower rooms should be tiled with ceramic effectively to make sure there is not seepage of damp into the partition walls or into the wooden central column of the building. The shower and sink outflow should be collected by PVC pipe and run to a single outlet where it will enter a grey water system.
Due to challenges with ensuring adequate cleaning/sanitation there will be no toilets inside the accommodation facility. Communal toilets will be located outside in separate men’s and ladies’ toilet blocks.
The partition walls between the bedrooms are made from heavy split-bamboo screens cut out to the required size and fixed in position with a light supporting frame of pole timber (eucalyptus). This can then be plastered with a thin layer (3cm on each side) of walling mud (more info on using Bamboo for “wattle-and-daub” building) to be covered over with 1cm of lime plaster, painted over with acrylic paint (white colour) or a local coloured clay suspended in a dilute emulsion of wood glue. Where the shower cubicles are concerned the bamboo can be covered with cement directly (3cm on each side) which will then be covered with ceramic tiles. The bedrooms should have plastic floor liner (or if it can be budgeted, be floored with ceramic tiles also).
Placement and Relationships
Key considerations in the placement of the guest accommodation facility are:
• Rainwater shed
• Grey water treatment and re-use
The guest accommodation is located 2m inside the (reduced) southern site boundary and 16.5m from the E site boundary.
Like the class room it is screened by barrier a barrier hedge from the west as well as by barrier hedges along the N and S boundaries to insure privacy for guests staying on the project. Access to the guest accommodation from the main entrance is from the west. There is also direct access from the staff accommodation/office from the NE. A pathway also rings the entire facility so that people can access any of the rooms from these two main entry points.
The waste water from the guest accommodation showers is collected and delivered by PVC pipe to the grey water garden. This is a treatment and re-use area which makes use of the grey water for year round production. It will also make use of grey water from the kitchen. The challenges in establishing an effective grey water system on this site are 1) the lack of topographic variety for delivery by gravity feed and 2) the heavy clay soil of the site which has very low rates of infiltration. The system developed is thus based on evapo-transpiration more than on infiltration. (See Grey water systems design later)
It is essential that rain water shed by the roof of the building does not enter the grey water system. The roof run-off may be made use of in semi-circular beds planted around the building, which may be somewhat pitted and heavily mulched to catch and infiltrate rain water. Pits like this have been used with success on the Konso Cultural Centre where they were used to grow banana trees and sugar cane. However, overflow from the infiltration beds will be expected in heavy rain due to the impervious clay soil. This must be directed to the west and excess water will leave the compound at the SW corner. This can be achieved by appropriate grading of the path surface.
The kitchen should proved the basic cooking facilities required for a local cook and one assistant to work efficiently and effectively in producing meals of suitable standard and diversity for international student groups to remain satisfied for periods of up to 2 weeks.
The kitchen facility should fulfil the following functions:
• Storage for perishables (ideally refrigerated)
• Storage for dry bulk foodstuffs (rodent proof)
• Storage for cutlery, crockery and cooking utensils
• Washing up
• Chopping and prepping surfaces
• A stove (or stoves) for cooking
• Structural Design
The kitchen should also provide a comfortable and clean working environment, well aerated, not too hot in the daytime, not too cold at night, with infrastructure so that the kitchen staff can work standing up or straight, not bending over all day or squatting on the floor.
The building has a 150mm thickness concrete slab foundation with stone-cement buttressing on the exterior. The walls are cob brick and there is no need for any additional columns since the walls will not bear load. The roof is a light timber frame with CIS. Alternatively roof tiles could be used if they can be sourced. The latter are more aesthetically pleasing and better for climate regulation, as well as possibly cheaper depending on market conditions. A machine for making roof tiles is available in Addis (Roof Tile Machine). This machine can be powered by a 12v system. This is also a potential local business industry as an alternative to CIS.) The building design has a single pitch roof which is angled south to form a base for solar panels.
The exterior walls can be lime-plastered both internally and externally. There is a single partition wall internally dividing the main kitchen room from the long term food store, which can double as a storage room for the solar battery bank, inverter and regulators, with the panels installed on the roof above. This store is located to the far right corner of the room from the entrance.
SMART have indicated that their preferred method of cooking is to use electric power derived from solar panels, during the day when peak charge will be more than the battery banks are capable of holding. However we recommend having a secondary power source for cooking such as gas or a wood-fired cook stove, though we leave it up to the operations and budgeting team to decide which.
In the design floor plan, washing up facilities are located to the right of the entrance with drying rack above. The grey water pipes with lead out to a centralised grey water system for treatment and re-use in an irrigated grey-water garden (this will also receive grey water from the accommodation facility showers). To the left hand side of the entrance is the plating up area, with plate store (for cutlery and crockery) above. To the left of centre in the room is the stove block with conical flue catcher (made of riveted sheet steel) up to a chimney which passes through the roof, with passive ventilator attached on top. The chopping/prep area is in the far left corner from the entrance with a storage cupboard for pots and pans above it to the left. The fridge for short term storage of perishables is to the right of this area directly opposite the entrance.
Placement and Relationships
The kitchen is placed in the SE corner of the site. It should be oriented with the long axis running E-W and the roof tilting to the south. The roof will form a holding surface for a bank of solar panels. It may be necessary to remove some of the large trees along the N boundary of the site since they may shade the kitchen during the mornings at some times of the year. If these trees are removed the timber can also be used for construction purposes.
The door to the kitchen is placed in the north facing wall. Herbs (such as rosemary, fennel, basil and rue) should be grown along either side of the pathway leading to the kitchen to be convenient for harvest and use in cooking.
Waste water from the kitchen should be delivered by PVC pipe treatment and reuse in the grey water garden. This is the same system used for grey water from the guest accommodation. The kitchen is located just to the east of the grey water garden.
A worm farm is placed at the eastern side of the kitchen building for disposal of solid food wastes. More information on establishment and operation of worm farms can be found here. The worm farm can be used to dispose of kitchen scraps and produce high quality compost and liquid fertilizer for the garden and tree nursery.
A rainwater collection tank should be placed at the SE corner of the kitchen building. This tank can be used for watering the herbs and garden beds around the kitchen area, however overflow from the tank must be directed away from the grey water garden which should not receive any additional water except for the grey water and direct rainfall.
Kiosk and Guard House
The kiosk is designed to be simple and functional. Since the Bonosha project is located in town which has a water supply, the function of the project is not to sell water to the community, as it is with the other SMART sites in Shashogo Woreda. Sales from the kiosk will comprise vegetables, as well as limited charging service (for mobile phones) when the town electric supply is down. Sales of surplus vegetables from the garden of the compound itself are likely to be small (if any) due to the limited amount of space and the need to use the produce to feed the trainees during courses. Thus there is no need to invest much into a large kiosk.
A simple 2 x 2m square building with a large window facing out onto the street at the SW corner of the site is sufficient. It should have a concrete foundation, with walls of either cob brick or cement block depending on whether speed of construction or economy with budget is a more pressing issue for the project. The roof of the building can be made with corrugated iron sheet (CIS) or using cement roofing tiles.
The guard house should be attached to the kiosk, so that they are actually two rooms of one building separated by an internal partition. Like the kiosk the guard house is a 2 x 2m square made using the same techniques and materials. The total area of the building will thus be 4 x 2m.
Placement and Relationships
The kiosk is placed at the SW corner of the site where it will be positioned for access from the both the S and W sides. The road to the south of the site is the main route to the market place for people coming to town from the countryside to the east. The guard house is positioned on the east side of the kiosk. The car park is next to the kiosk and guard house to the north, so that parked cars are close for security. The store is also near-by.
Store and Seed Bank
The main store will be used to keep three main categories of materials:
• Construction and garden tools and unused building materials such as cement etc.
• Hospitality materials such as spare sheets, blankets, mattresses, tents, mosquito nets etc,
• Food items including produce from the garden and/or other SMART sites which is awaiting sale or use in the kitchen.
The seed-bank and store are two functions of the same building but are divided by an internal partition. The reason to divide these two functions is the need to keep the seeds well organised in their own space and protected from disturbance. It is also to prevent access to the seed bank by kinds of pests which may enter the main store along with materials and equipment.
Like the kitchen and kiosk/guard house the building should be constructed with a concrete slab foundation and cob brick walls with a single pitch flat roof. The roof can be made from cement roof tiles or CIS as decided by SMART’s operational team. The pitch on the roof should slope to west into a gutter set on the front of the building (i.e. where the side on which the entrance is located). There should be a water tank placed at the NW corner of the building to catch the roof run off, so that it can be used for the animals (which are penned just to the North)
The store should have strong metal shelves ideally 50cm wide and accessible for both sides, which are able to support the weight of such bulky materials. There should be three separate banks of shelves one exclusively used each of the three categories. The different categories should not be mixed as this would allow cross contamination (e.g. food-stuffs contaminated by building materials). The floor area of the main store will be 3m x 4m, which is enough space for materials to be easily accessible and not end up crammed in on top of each other – which leads to loss of materials and waste, and encourages invasion of the store by vermin. There should also be a desk and chair in the store room at which the store-keeper can keep records such as bin cards, goods receiving and issuing vouchers. There should be an electric socket and at least one electric light in the room.
Seed-bank operational protocol can be taken from the following write up: Oct 2014 (b).
Location and Relationships
The store and seed bank are placed on the E site boundary on the other side of the car park from the guard house. This allows close supervision by the guard. They are also near to the tree nursery and shaded work area, so that tools and seeds are close to hand for garden tasks such as seedling preparation, composing etc.
Animal Housing and Animal Pen
The animals that will be kept in the house include a single dairy cow and two sheep. The main reason for keeping the animals are:
• To recycle vegetable wastes from the garden and kitchen
• Provide a source of manure
• Provide milk for the project staff.
• 4+ lambs per year from two ewes will provide a source of meat for the kitchen
The animal housing is to be located north of the seed-bank/store, adjoining onto its northern wall. The roof may be a continuation of the same structure. However the animal house need not have a concrete foundation. An earth floor, raised 10cm from ground level is sufficient. The structure should be timber framed (Eucalyptus pole) with bamboo screen lattice walls. The dimensions of the animal house will be 3m x 2.25m. However the roof will extend over an un-walled area 1m longer to the east, which will serve as a feed store for the animals. A rainwater tank placed at the NE corner of the animal housing roof will harvest water from the roof of animal housing, seed-bank and store via a single gutter on the eastern edge.
The animals will not be ranged inside the project compound. A pen of 5 x 4m area is set to the north of animal house. The pen should be well fenced with stout timber poles and barbed wire to prevent them breaking in to the main project garden. The pen has a gate to the exterior, through the main compound fence (shown in heavy black in Fig X below) so that the animals can be allowed out to range on local commonage for daily exercise and additional forage.
A feed rack and drinking trough are located in the pen. The project’s composting area is set directly to the north of the animal pen so that manure can be shovelled over for composting on the other side. The water trough can be filled both from a tap (connected to the main tank) fixed at the NW corner of the pen (which also supplies water for composting) or from the rain-water tank (when not empty).
Access to the feed-store is from outside the pen and the animals can be fed and watered from within the main compound without the need to enter the pen itself, since the feed rack at edge. However access to the pen and the animal house itself is through the feed store, so that feed can be carried into the pen while entering.
The project will have a flock of 10 – 15 chickens. These will be housed and ranged within a mobile pen or chicken tractor which can be moved on rotation through various different parts of the gardens to clear beds, till soil and add fertility. A simple design of chicken tractor which includes a roost, nesting boxes space for foraging on the ground and well as supplementary feeders is outlined here: Oct 2014 (a). The tractor can be made from 6 x ½” steel pipes and 20m2 of heavy gage 1” steel mesh. It is fully mobile, predator proof, light and durable.
The compost toilets are primarily for use by trainees attending courses. The staff can continue using the flush toilet in the existing guest house. The compost toilets follow a standard double-chamber design without urine separation, meaning that a high carbon additive such as sawdust must be added on a reliable basis after every use. Urine separation was not selected as an option because it complicates cleaning and creates more potential for breakages and mismanagement. The floor of the lower storey should have be gently sloping towards a 100mm PVC outflow pipe (in the same way as a local concrete-based shower), which will collect any liquid seepage and run it into a mulched trench. This trench will also receive grey water from the hand washing station.
The lower storey of this toilet design is founded on a concrete slab foundation. The walls of the lower storey are concrete block 20x40x20cm. Maintenance access for compost removal is from the back side at ground level.
Sizing the lower chambers
It is assumed that the training centre will to run a maximum of 2 courses per month, of an average of 7 days length, meaning the use rate should be an average of 14 days per month. Assuming a maximum of 12 trainees per course, that is 168 person-days of use per month.
Next we assume that a user will deposit solid waste once per day and liquid waste 3 times per day. Following each use, the user should add 100g of sawdust to the pit. The volume of an average solid waste deposit is estimated at 100cc. The volume of 100g of sawdust is estimated at 200cc. Hence it is estimated that the average user will deposit this amount of material each day:
This means the total volume of material deposited in a month will be:
If we decide we want the material to have 6 months decomposition time before being removed from one chamber then we should allow for 6 months worth of storage capacity, which in this case would be 0.12 x 6 = 0.72m3. Hence we can make the lower storey chambers at 1m3 internal volume to be sure we have some extra capacity.
The upper storey of the toilets can be made of cob-brick or cement block as decided by the operations team. The roof may be CIS or cement tile. The floor between the upper and lower chamber should be re-enforced concrete. The actual toilet seat should be placed in the centre of the upper chamber and raised up 40cm above ground level. The aperture leading to the lower chamber should be 25mc wide to avoid it getting dirty by excrement or faeces.
The upper storey of the toilets should be partitioned and the side which is not in use should be locked to prevent people using it. Use access will be via steps at first floor level. The roof should be sloped to insure that rain run-off does not enter the mulched infiltration trench which receives grey water and seepage from the CT units.
A 100mm PVC pipe should run from the top of lower chamber, through the concrete floor and exit through the roof. This air vent is topped with a passive ventilator to draw airflow up from the lower chamber out into the atmosphere. This will insure a continual air flow through the lower chamber to keep the material well aerated and aerobic. Air inflow vents are set into the lower chamber from the sides at the bottom. Two 100mm PVC pipes enter from the side and pass right across the bottom of the lower chamber. These are cut into half pipes, forming an “inverted U” in the central portion so that air can enter from below the waste material and the inflow vent will not be blocked even when the chamber is full of material.
Maintenance and Operation
It is critical to the effective function of the toilet that there is always a ready supply of sawdust in the toilet upper chamber for users to add after each deposit. If sawdust is not added the toilet will stink and the breakdown process will not produce good compost. The project staff must be adequately briefed and committed to upkeep of the system in order for it to work. Clear instructions on use should also be present inside the upper chambers.
Before the toilet is used a bed of 5 – 10cm of sticks should be laid down on the ground. This should then be covered over by another 5 cm of straw or dried grass. The sticks and grass should be up the level of the top of the air vent pipes running in from the side. This is to maintain aeration of the organic material in the chamber from underneath. The toilet can now be used until the lower chamber is filled with material – which is anticipated to be 6 months. When the lower chamber fills up, that side of the CT is locked and use begins on the other side. By the time the second side of the CT has filled up another 6 months should have passed. By this time the material in the first half is expected to be fully decomposed. It can now be shovelled out and use of the first side of the CT resumed.
Even if the material is fully decomposed it may hold some residual pathogens, such as protozoan spores or worms eggs which are not decomposed in the slow breakdown process. Hence the “humanure” compost should not be used on vegetable beds. It is most suitable for using under mulch for animal fodder crops or trees.
There should be two separate toilet units, one for men and one for women. A single hand wash basin should be placed between them so that users can sanitize their hands after use. The grey water from this hand wash as well as liquid seepage from the two toilet units should all feed into a single drain which runs into a mulched swale. This will give underground irrigation to the crops planted in the swale which may be fodder crops such as Napier (“elephant”) Grass or trees, such as bananas.
In the overall site design the trainee toilets and are situated behind the class-room along the N boundary. The underground pipe-drain will run along the back edge of the two CT units with all four chambers as well as the hand wash basin draining into it via concrete junction boxes. The junction boxes have a lid to allow inspection and removal of blockages if necessary. The mulched swale/trench will run from just (1m) past the east end of the ladies toilet for a distance of 8m, parallel to the edge of the pathway running behind the class-room. It will reach to 1m from the staff shower. The staff shower should not empty into this swale but has its own infiltration swale on the other side. The pipe drain will enter the swale at the west end. Here it will enter another junction box with inspection cover. The outflow from this box is a slotted 100mm PVC pipe with slots every 30cm. This pipe is buried under 30cm of mulch and runs along the length of the swale for 6m.
Nursery and Shaded Working Area
The tree nursery is an area arranged to provide ideal conditions for the germination and first 6 months growth for tree seedlings of mid to high value. The rational and design features of a tree nursery are explained in detail here: Oct 2014 (b).
Shade frames, pathways and holding beds
The ground-plan of the tree nursery should offer ease of access so that that seedlings can be placed, removed and moved around easily. Internal pathways should be 50cm wide and surfaces with sand or gravel to make sure they do not become muddy. Seedling beds should be slightly raised from the level of the pathway so that they shed water and do not end up holding water around the base of the seedling tubes in the heavy clay soil of the site. Ideally the tree seedling beds should also be surfaced with sand to ensure good drainage. The beds should be divided into 1m2 cells which can be labelled with marker pegs, to allow separation of seedlings by category such as type, age grade etc. These cells can be formed with pole timber. This process has been demonstrated to SMART project staff in 2012, refer here for details under Physical Activities Section, Task 2: October 2012.
Shade frames should be made from Eucalyptus pole and topped with light bamboo lattice screens. They should be at least 1m high above the ground. Ideally the top of the should be angled slanting to the west so that morning sun can shine in from the east but that afternoon sun from the west is excluded.
The area set aside for the tree nursery frames in 7m x 4.5m which is enough to hold 21m2 of bed area with pathways in between. Each m2 can hold around 400 tree seedlings, hence this area should be enough for a nursery of over 8000 seedlings. Some of the beds can also be used for vegetable seedlings to stock the garden (on site as well as for other SMART sites in Shashogo).
The tree nursery is placed near to the tool-store, seed bank and composting area as well as being close to the main entrance so that all equipment and bulk materials needed for preparing potting mix, seedling tubes and planting seed are close to hand and do not need to be carried far. This is essential for ease of work.
The nursery is also placed to receive morning sun from the east, but will be shaded in the afternoon by the store and seed-bank building. Afternoon shade is an advantage since the seedlings can be watered between 4 – 5pm and will be shaded allowing soakage and absorption of water without evaporation loss going into the cool of the evening.
Shaded Work Area
The tree nursery in this design is placed next to an open shaded work-area of 5m x 6m area which can be used for the preparation of tree seedling and other physical tasks which relate to garden maintenance and operation such as composting. This area should have a shade frame raised up 2m above ground level so that people can comfortably move around and work underneath it. A durable material such as steel pipe would be ideal for the shade frame and supporting columns so that perennial vines such as grape and passion-fruit can be grown over the frame to form a permanent natural shade cover. Initially bamboo lattice screens will need to be attached to the shade frame roof, but these will degrade in the long term to be replaced by the vines.
Grey Water Garden
There are two main challenges in developing an effective grey water system for this site:
1) The very low permeability of the clay soil
2) The lack of topography for directing water around by gravity feed
Grey water should be treated by settlement and skimming prior to land application under deep mulch. The details of an effective grey water system which uses no pumps or mechanical parts made from low cost materials are outlined here. The settlement tank in this system comprises a 1000L IBC which is encased in a concrete frame. We suggest copying this aspect of the design outlined in the article. The IBC will need to be buried underground so that water can flow downhill to it from the kitchen and accommodation facility. It should be capped over with concrete to secure it in place and protect it from damage.
The outflow from the system then flows into a deeply mulched land application area. This is a 1m deep excavation 6m x 8m in dimensions. Due to the very low permeability of our soil our application area needs to be deep, wide and heavily mulched. The excavation is backfilled to 30cm depth with 20mm gravel. 100mm PVC slotted distribution pipes are buried in the gravel at 10cm depth. Above the gravel the rest of the excavation will be filled with organic mulch material. Soil and compost can be added into this around plantings. Since infiltration will be low the area should be planted up with heavy feeding trees that draw up a lot of water, such as bananas. Avocados can be planted around the edge of the application area to draw out excess moisture from the edges.
Take a course with Alex!
- Permaculture for Development Aid: 5-day Course with Alex McCausland at PRI Zaytuna Farm, NSW, Australia (Begins January 19, 2015)