Interview Water-cycle on Texel with an employee of HHNK

This is the interview we did for the water-cycle group during the visit on Texel. We spoke with Nico Tessel, an employee of the HHNK on Texel. Nico is responsible for the water management & treatment on the island and we met him on the water treatment plant Everstekoog were we also had an interesting guiding tour.

1. What is your current function within the HHNK and for how long do you have this position?
I am just a technical employee and I have no specific function, it is very omnifarious. I am responsible for the water management as well as the treatment plant we’re now at. I have been doing this for 3 years now, before this I worked in Noord-Holland, also in a water management function.

2. I have some other questions regarding our research..

- How does HHNK cooperate with the municipality of Texel?
Well, we supposed to cooperate but in practice this only happens in cases of emergency, for example flooding. In recent times of extensive rainfall we worked together with the municipality to minimize the effects and I am quite satisfied with this cooperation.

However, the municipality does not have a money tree on the Island. This means that there’s too little budget to really cooperate in making the system more efficient.

- What are the most important actors in the water system on the island?
PWN for drinking water, municipality as owner of the sewage system and the HHNK for water treatment and maintenance of the pipeline. The provincial government has no influence on the water system on Texel.

- What is the capacity of drinking water storage on the island?
You should ask PWN because I am not sure, but I think a supply for 3 days is needed.

-What rules and regulations are important in the system as far as you concern?
I don’t exactly know which rules and regulations are important but I do know that we have to monitor the quality of the treated water. Every 14 days we send samples to Hoorn were the quality is checked.

3. So what do you think are the biggest disadvantages of the current water system on Texel?
The biggest problem for now is, as you also pointed out, the lack of clear separation between rainwater and waste-water from the houses; these both end up in the sewage system. On a rainy day as today a lot of water is coming into the treatment plant of which a large part consists of rain water that does not actually have to be cleaned. The rainwater should be captured separately and stored as fresh water supply for agriculture.

Another problem in the current treated water is the residue of medicines used by people. With current methods it is too expensive too also take this residue out. This means that the water cannot be reused for drinking water purposes.


4. What do you think of a self-sustaining Island and what would you expect of a future self-sufficient water system on the Island?
Well, Texel was self-sufficient in terms of water 30 years ago.. But because of rising tourist numbers we could not fulfil the demands during summer anymore. This makes the pipeline necessary nowadays. In order to become self-sufficient a solution for the peak moments during the tourist season should be found.

Furthermore, I don’t know what to expect of a future self-sufficient system; I think things are already well arranged here on Texel, except for the sewage system which is outdated at some parts. Next to the water treatment plant a zonneweide (a parcel filled with PV-panels) will be built soon. This will consist of 3000 PV-panels and is also contributing to a more self-sustaining future.

*We also had contact with PWN, the drinking water company. They told in the email that a self-sufficient water system on the island would be very impractical because of the big peak demand during tourist season. This is economically unfeasible and would require a treatment plant with a big overcapacity. We should look at the following regulations that will confirm the complexity: leveringszekerheidwetgeving in the Drinkwaterwet and the Drinkwaterbesluit.

5. Other things that became clear during the visit or are interesting regarding our sub-system.
The ditch-system acts as one big water buffer. The water level in winter is on average 40cm lower than during summer. In February they start stacking the water in the ditches by means of 900 locks (of which only 56 are automated) to create this buffer and allow a natural stream. This water is then used in the summer to irrigate the land.

The cane in the ditches has multiple functions. It has an important function in the ecosystem of the island, providing a habitat for many organisms. The cane also helps strengthen the banks of the ditches. Another interesting reason why we want the cane to be in the ditches is the fact that it stops evaporation of the precious water. Because we use the ditch system as water buffer we want it to stay there. Without the cane protecting the water from the sun, up to 1cm of water a day could evaporate.

Every larger city has a storage tank for the wastewater of the households before it is transported to the treatment plant Everstekoog. The smaller villages have a tank of 20m3, the biggest town Den Burg 100m3. The water is sent to the treatment plant from these tanks according to the amount of water inside. This allows a changing distribution of waste water, according to the intensity that is required. This is a very useful feature.  

The treated water can be released in 2 directions and this effluent is powered by 2 pumping stations on both sides of the island. The flowrate can be up to 350m3/minute.

Houses and smaller communities that are far away from the cities are not connected to the centralized sewage system. A total of 11 smaller IBA’s (small scale water treatment facility) accommodates the treatment of the waste water here.

- Interview by Jesper Goorden




Jesper Goorden

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