Dear Elisabeth, 

Thank you very much for sharing my survey. That is extremely kind of you. Also, I would like to thank everyone for giving me their expert opinions. Your opinions are very helpful.

Kind regards,

Emilie

Hi Rick,

I wish Emilie best of luck with her research and survey! The closing date was given as 10 July but luckily the survey is currently  still open.
I am a great supporter of MSc students, their work and surveys. For this reason, I was curious to see what Emilie's survey involved even though I am not an expert in septic tanks. So I clicked through the survey (one thing I was missing was a progress bar; the survey is quite lengthy). Reading through the survey you can learn a lot about the hazards linked with septic tank systems! I copy here the main survey questions below which might entice some people to take Emilie's survey if they are knowledgeable on septic tanks. I think Emilie will be grateful to receive more survey responses!

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Calibration questions:
Assuming the drainage field is in a sand or loam material, and there is no lateral movement of liquid, what would be a typical safe vertical distance (in metres) from the bottom of the drainage field to the highest groundwater table to remove most pathogens?

Assuming the drainage field of a septic tank system is in a sand or loam material, and there is no lateral movement of liquid, what would be a typical requirement in travel days from the absorption trench for viruses to be removed.

What is the typical target retention time (in hours) of liquid in a septic tank serving one to two households.

Expert elicitation questions:

Realistically, what do you think is the lowest plausible risk that groundwater pollution from the containment of septic tanks will lead to health effects (Enter a value from the matrix)?

The standard risk matrix:

 

Realistically, what do you think is the lowest plausible risk that local water course pollution from the containment of septic tanks will lead to health effects (Enter a value from the matrix)?

Realistically, what is your best estimate for the plausible risk that backing-up of sewage from the containment of septic tanks will lead to health effects?

Realistically, what is your best estimate for the plausible risk that the discharge from solids from the containment of septic tanks will lead to health effects (Enter a value from the matrix)?

Realistically, what is your best estimate for the plausible risk that surface flooding from the containment of septic tanks will lead to health effects (Enter a value from the matrix)?

Realistically, what is your best estimate for the plausible risk that odours from the containment of septic tanks will lead to health effects (Enter a value from the matrix)?

Realistically, what is your best estimate for the plausible risk that a tank full of groundwater/a tank that lifts will lead to health effects (Enter a value from the matrix)?

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Regards,
Elisabeth

Emilie Wesseling is an MSc student at TU-Delft, working on on-site sanitation. For her thesis she wants inputs from sanitation experts to prioritize hazards linked with septic tank systems. If you have 15-20 minutes to help her out please take this survey here: www.surveymonkey.com/r/on-site-sanitation-hazards. The survey will be open through 10 July.

If you have any questions in respect of the survey, please feel free to contact Emilie at This email address is being protected from spambots. You need JavaScript enabled to view it..

Thanks!