Besides all the handpumps, windmills and solar collectors, the WOT-terrain also maintains a garden bed for growing vegetables.

For irrigation 3 different systems are tested in the garden. A bought irrigation hose, a flower pot based system and a system made from plastic milk bottles. The systems are applied in rows perpendicular to the rows of different vegetables. The conditions on the field are relatively constant but it is only a few square meters so drawing conclusions on the yield of the plants is not really justified. The main goal of the experiment is to discover advantages and disadvantages of the systems and not to perform a scientifically justified comparison. First all three systems will be described, later updates will be placed to comment on the systems.

Irrigation hose

First of all there is the irrigation hose. This is a readily bought polymer hose produced by REHAU. The material of the hose possesses the property to ‘sweat’ so that when water is inside this slowly enters the soil. To ensure a constant water supply, we’ve connected this pipe to our water tank. The pipe is buried at a depth of approximately 20 cm.

Because the water directly flows into the soil less water evaporates.The company claims that by using this system correctly, up to 70% of water can be saved compared to conventional watering. A 15 meter pipe was bought for approximately 20 euros.

Ceramic Plant pots

The second system is based on flower pots. Unglazed ceramic pots possess a similar property to that of the irrigation hose. The material is porous and when there is dry soil around the pot water is ‘pulled’ through the material. When the ground is wet however, less water will flow through the ceramic material. This method is a proven system for irrigation and so called ‘ollas’, pots with a large body and a smaller neck, have been used for a long time. The pots are buried and plants are placed in the vicinity of the pot, the roots grow towards the olla and the plants always get the right amount of water.

Pottery with a shape similar to the ollas, relatively expensive in the Netherlands and the skills to make them ourselves we do not possess. Therefore we decided to make our system out of unglazed ceramic flower pots. These are both cheap and readily available. The large opening of the pots were closed off with other pots and sealed with sealant. The hole in the bottom of the pot was fitted with a cable gland so that a garden hose could be attached to it. Several of these pots were connected and attached to the water supply. Two different designs have been made.

Plastic jugs

Finally a system made of plastic jugs is tested. Small holes are poked in an empty plastic milk jug. These jugs are buried, filled and the cap is fermly put on. The principle behind this method is that because the cap is on and because there are such small holes, air can’t easily enter the jug and thus water doesn’t flow out easily. Because of this water is dispersed over a large amount of time. Also if the ground is wet, possibly, this causes the water flow to decrease even more since less air is present in the soil. Because we did not know the effectiveness of this method and we didn’t exclude the possibility that water would flow out at a to large rate, we didn’t connect this system to the water storage for a continious water supply. The jugs were to be filled manually.

Below are some pictures of the setup of the complete system. Updates of the operation of the systems will be given in the future.

Flow controll

In order to be able to control the flow going to each system, a clamping system was made. It is shown below. One tube goes to the irrigation hose while the other goes to ceramic pots.

At the beginning of 2019, a request came in from Maarten Rijgersberg, IN KNOWLEDGE / ExpositionRent, a company that rents interactive exhibitions in the field of environment and nature. They were interested in a model made in the past by WOTters in which a rope pump pumped water to another container so that fake flowers slowly floated upwards. They also wanted a normal demonstration model of a rope pump. A model in a mortar tub has been refurbished and repainted. The flower rope pump no longer existed and it was decided to rebuild it. The flower rope pump demonstrates two things: 1. The operation of the rope pump, a very cost-effective pump used a lot in developing areas. At the WOT we have a lot of experience with this type of pump. Read more about it here. 2. The call for more biodiversity through planting more plants is increasing worldwide. Decreasing the amount of pavement in gardens and public spaces is a must, considering the dramatic decline of insect life around the world. According to this study by Radboud University in 2017, there has been a two thirds decrease in the insect life in the past 27 years. Partly with the flower pump rope pump, ExpositionRent, together with other demonstration objects and exhibition materials, wants to direct people to greening gardens and thus stimulating life. The Flower Box Rope Pump can be rented for Festivals & Events, Municipalities, Environmental Education Centers, Visitor Centers and Museums. via the website of ExpositionRent.

First, a plan was drawn and the design was carefully considered. The model would have the same principle as the previous version, but would be more robust. Due to regulations, it was important that the pump would be child-friendly and that no one could lose their fingers. The entire box would be closed with a number of parts made of transparent plastic so that people could look inside. When the plan seemed comprehensive (that was of course not the case), construction started.

A large sheet of plywood was bought along with a sheet of plastic and a pot of rubber seal. The plate was cut into the correct pieces based on the drawings. This has resulted in a lot of puzzle work and despite the fact that (as usual) something has been cut wrong, everything ended up quite well at this point. Work was also carried out on the PVC parts and steelwork. Furthermore, the flowers had to be made. The plastic rubish from the store turned out to be too fragile. That is why the flowers are made of sheet steel with styrofoam floats.

The box slowly but surely took shape. The wood was covered with a large number of layers of yacht varnish and the metalwork was painted. The outside of the box was also painted and the plastic cut to size. At some point it was time to do the first test with water. The workshop was temporarily transformed into a swimming pool. There were leaks at seams between the wooden plates and at the connection between wood and plastic. More sealant and rubber seal seemed to partially solve the problem. However, accessibility for maintenance proved to be a difficult problem. In order to be able to enter the tank, the top had to be able to come off, so it was not possible to seal everything shut. After the workshop floor already had to endure a lot of moisture, the majority of the leaks have been fixed. When pumping, however, water still splashes around in the top part of the container and some water will leak.

During the work, most of the plastic has been replaced, it has been discovered that silicone sealant that has expired does not harden, that children have to pump very hard to get flowers up and much more. But in the end the model was finished. The container was delivered about ten months after the request. A project that took longer than expected and was more complicated than initially planned, but very educational. And it is of course very nice that a WOT production is now part of an exhibition. Perhaps more models will follow in the future.

It was no longer operational and started to deteriorate further: the solar collector made of beer bottles, garden hose, and PVC. During tours, it was quickly passed by, so we had to do something about it. Nothing was reusable from the old collector, so it was decided to use the renovation as an excuse to increase the capacity. Two glass plates of the same width (85 cm) were found in storage, which together had a length of 210 cm. So that had to be the new format. At the hardware store, it turned out that luck was with us because 210 cm turned out to be a standard length for planks.

The box was built from wooden plates, planks, and battens connected to angle brackets. A double bottom is made with insulation plates in between. The entire box is primed and finished with two layers of blackboard paint. The black, matte colour gives the best result for heat absorption.

The next obstacle was the storage system. We opted for a complete PVC system with as big and many pipes as possible, which were connected to standard couplings. The box turned out to be able to host 8 tubes of 80 mm using 40 mm connectors resulting in a total capacity of approximately 65 liters. This is almost twice the capacity of the old system!

In the meantime, the idea had arisen to completely close the box, with the option at the bottom to remove a plank and to slide out the entire storage system. As a result, the glass plates never need to be removed, which reduces the risk of breakage. Ironically, one of the glass plates was broken when cutting to size (a piece had broken off in the past and this had to be cut straight again). Attaching the 40 mm pipe to the shower’s 16 mm garden hose required a series of flared pipes to achieve the correct diameter. At the same time, this should not protrude too far, which would eliminate the possibility to slide the system out of the box. As a result, the hose could not be secured with a hose clamp due to lack of space. Cutting thread on a piece of PVC pipe seemed to be the solution, but the connection could not be made waterproof. In the end, a PP hose nozzle was used which is not really compatible with gluing to PVC.

All in all, the renewed solar shower was prepared just before the T-week, where it was frequently used by the enthusiastic participants and volunteers. It quickly became clear that the connection of the hose nozzle was leaking a little and when the water is warm, the garden hose softens a little bit and can come loose. So this is another point for improvement for the future.

During the T-week, a thermometer was installed in the tank, which indicated temperatures from 40 to 50 °C in the sunny weather we were in. Adding a little cold water is all it needs to have a comfortable shower!

Now that the solar collector has been replaced, the renovation of the corresponding cubicle is next on the agenda.

For some time now the wooden pump frame has been in a bad condition. Due to this pumping was not possible anymore. After a long time of lying around, this summer the components of the pump were dusted off and the renovation was a fact. Most of the wood was rotten and had to be replaced, although some components could be re-used. Nevertheless the renovated pump wasn’t to be as colourful as the old version, so the components that had not rotten still had to be cleared from their old coating. Instead of paint, the wood would now be stained. The steel piping and base plate also required some work, and were repainted in a colour best described as british racing green, or simply darkish green. With the use of the construction manual and old pictures the frame was assembled.

But before all this, the pump itself had to be checked and mounted. It turned out that the top of the pumping rod was missing. Therefore a piece of rod was cut at the right length and mounted to the existing rod. At this moment the pump seemed to be complete, and assembly of the pump was the logical next step.

Nevertheless it was evident quickly that the pumping did not go well. The water that was collected seemed to be flowing back into the well, so that all the pumping effort was in vain. The pomp was drawn from the well, and opened up for inspection. In order to open the pump, it had to be dissected, a system that proved inconvenient. When the pump was opened the piston valve turned out to be jammed. As it was loosened it was free to move again. Another interesting observation was the large amount of sand and debris in the system, this explained the jamming of the valve. Besides this the components appeared to be alright. After the pump was cleaned of dirt the gauze at the bottom of the pump was replaced with a finer grid gauze so that less debris would be able to enter. After this the pomp was assembled in a more convenient way than previous, using steel plumbing parts so that the pumping tube could be easily mounted to the pump. Now, finally, the pump could be installed.

And it worked! The water was slightly dirty at the beginning, but this problem solved itself quickly. One drawback of the system however is the fact that the well empties quickly. Whether this is because the pump is to high in the well or whether the sublime renovation made the pump to good for the well, is still subject of discussion.

Wednesday 12-9-2018

Tour and dinner on our terrain at 18:00 with afterwards a drink.
To join dinner please e-mail wot@utwente.nl before 16:00.

Wednesday 19-9-2018

Presentation about the current projects at the WOT.

Wednesday 26-9-2018

WOT-member Hilbert-Jan will be speaking about his experiences in Ethiopia.

29 and 30-9-2018

A whole weekend of WOT-fun!

Wednesday 3-10-2018

Sunday 7-10-2018

Wednesday 10-10-2018