Safer siting of sanitation systems: An introduction to criteria for risk reduction to groundwater quality (discussion of draft)

  • kanalwolf
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Safer siting of sanitation systems: An introduction to criteria for risk reduction to groundwater quality (discussion of draft)

Dear colleagues,

In response to the discussions on the forum with regard to the safe siting of sanitation systems we thought to draft a small "checklist"-document on this topic.

The intention is to illustrate the most basic rules, to raise awareness and to inform about entry points for a more detailed approach.

Attached you find a first draft document, not for quotation but as an invitation to comments and suggestions for improvement.

We hope to discuss the suitability, usefulness and the content of the checklist-document during the upcoming SuSanA Meeting in Stockholm, 5.+6th of September. If there is sufficient interest, we will have a working group meeting on the 6th of September, 11:00-13:00 in Stockholm.
SuSanA draft meeting agenda

Kind regards,
Leif

Dr. Leif Wolf
SuSanA WG11 co-lead


Dr Leif Wolf
Co-Lead of Susana Working Group 11 : Sanitation & Groundwater Protection

Program Manager at PTKA

www.researchgate.net/profile/Leif_Wolf/

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  • kanalwolf
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Re: Safer siting of sanitation systems : An introduction to criteria for risk reduction to groundwater quality

UPDATE:
Thanks for the various useful comments to the checklist document recieved so far via email.
If you like, please comment also in the forum, then more people can participate in the discussion

Especially I liked the comment that probably good practice in well constructiion (especially approproiate sealing of the annular space) is one of the most important ToDo´s in having safer groundwater supplies.

The time slot for the working group meeting in Stockholm is now planned for 6th September between 11:30-13:00.
If you would like to participate and contribute, please let me know. Please also note that we will be happy to feed in your inputs during the meeting in case you will not be present.

If you have instructive photographs which show situations where groundwater is at risk from sanitation systems, please share those pictures with us (via the WG11-Forum or via email to This email address is being protected from spambots. You need JavaScript enabled to view it.). Probably a collection of “Don´t Do It Like This”-photos will help further understanding.


Dr Leif Wolf
Co-Lead of Susana Working Group 11 : Sanitation & Groundwater Protection

Program Manager at PTKA

www.researchgate.net/profile/Leif_Wolf/
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  • JKMakowka
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Re: Safer siting of sanitation systems : An introduction to criteria for risk reduction to groundwater quality

It has probably been mentioned to you by email, but a small section on flood risks would also be good.

Edit: more than one sentence :huh:

But also see: wedc.lboro.ac.uk/resources/conference/25/041.pdf

Microbiologist & emergency WASH specialist
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  • prthomas
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Re: Safer siting of sanitation systems : An introduction to criteria for risk reduction to groundwater quality

Hello,

This is an excellent document for public education on siting of septic systems. In Ontario Canada we have number of municipal wells and it has been legislated here 4 zones around a municipal well.

• Wellhead Protection Area WHPA-A : 100 m Radius
• Wellhead Protection Area WHPA-B : 2-Year time of travel
• Wellhead Protection Area WHPA-C : 10-Year time of travel
• Wellhead Protection Area WHPA-D : 25-year time of travel.

Also, there are septic re-inspection programs to check the septic systems within these time of travel.

You might have heard that Ontario has stewardship grants to owners of septic tanks located in the Wellhead Protection Areas for retrofits/rehabilitation. Also there mandatory septic tanks inspection programs as well.

Thanks and Best Wishes.

Percival


Percival R. Thomas, PhD, P.Eng.
Manager of Water/Wastewater Systems
City of Orillia
Environmental Services - Engineering
50 Andrew Street South, Suite 300
Orillia, Ontario L3V 7T5
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  • christoph
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Re: Safer siting of sanitation systems : An introduction to criteria for risk reduction to groundwater quality

Dear all,
the document is nice and clear in its layout, explaining the problem in a clear manner to nonprofessionals. I get the impression that it is meant for nonprofessionals.
But especially nonprofessionals would need examples. Explaining "what is close and what is far" in reality. In the document is mentioned 10 m as close (as it is so close that in all situations it is close) and 1000 m as far (so far that it will never be relevant).

Any quantitative information on separation distances provided within this document are general examples only. For application to your site or setting, it is strongly recommended to consult groundwater professionals to elaborate specific guidelines which are adapted to the regional setting.

The second zone is delineated at the line from which groundwater travels 50 days until it reaches the production well or spring.

I think you should include examples as: a 50 day line in sandy soils is about ...m whereas in loamy soils it is ... and it can go up to xxx m in fractured rock. Just to make clear for a non professional how extreme the difference could be.
How many people in areas with household wells have a groundwater professionals to elaborate specific guidelines .... so they need orientation to understand the reason the distance varies between "between 12 to 75 m between pit latrine and groundwater wells" in guidelines.

Regards
Christoph
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  • JKMakowka
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Re: Safer siting of sanitation systems : An introduction to criteria for risk reduction to groundwater quality

Hmm, but that can become very quickly very complicated see for example the attached guidelines.

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  • christoph
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Re: Safer siting of sanitation systems : An introduction to criteria for risk reduction to groundwater quality

Hi Kris,
I thought of something like the Table 8.2 in the document you posted. To explain with a bit more imagination possibility for distances the problem.


Nothing sientific for all cases.
Christoph
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  • kanalwolf
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Re: Safer siting of sanitation systems : An introduction to criteria for risk reduction to groundwater quality

Hi All,

Many thanks for the feedback and good suggestions to Kris, Christian and Percival.

I agree that it could be valuable to provide a bit more examples on separation distances.
However, I think that we need to make clear also to non-professionals that the idea of having a uniform separation distance for an entire country is most likely not the best approach.

E.g. even 50 m lateral separation distance migth not be sufficient in a strongly karstified system with a downgradient supply well or spring, while 10 m lateral separation distance is completely sufficient if there is a well developed clay cover layer and the annular space of the well is nicely sealed.

Ok. let me dream a little bit:
Possibly the best approach (if there is enough expertise available) would be to develop for each district or urban area an intitial water safety plan which 1) maps major and minor groundwater uses for drinking water 2) displays broad groundwater flow directions 3) maps the groundwater vulnerability based on criteria like karstification or vadose zone thickness / composition 4) maps high and low risk areas with corresponding minimum lateral separation distance regulations and 5)identifies the ability of residents to implement the recommended separation distances.

As for the checklist document, I will try to include
- more information on example separation distances,
- an explanation why it is completely sensible that so many separation distances were defined by different people ( in gross simplification of the real complexity of the problem)
- a simplified version of the table which Kris extracted.

Would this address your points?

Cheers,
Leif


Dr Leif Wolf
Co-Lead of Susana Working Group 11 : Sanitation & Groundwater Protection

Program Manager at PTKA

www.researchgate.net/profile/Leif_Wolf/
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  • kanalwolf
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Re: Safer siting of sanitation systems : An introduction to criteria for risk reduction to groundwater quality

Dear All,
Thank you again for the helpful suggestions from the forum.
It was very quiet in this post because it took us some time to respond to feedback and also we added some subchapters.

Please see the final draft attached to this post. It is currently also for review with the SuSana core group.
If you have minor comments, please let us know before 30th of January and we will try to take them on board in this 2015 version before we publish it. Major suggestions however will be collected for the process of composing the next edition (probably in 2016)

Kind regards,
Leif


Dr Leif Wolf
Co-Lead of Susana Working Group 11 : Sanitation & Groundwater Protection

Program Manager at PTKA

www.researchgate.net/profile/Leif_Wolf/

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  • F H Mughal
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Re: Safer siting of sanitation systems : An introduction to criteria for risk reduction to groundwater quality

Dear Leif,

Attached is 1984 publication of the World Bank titled “Manual on the Design, Construction and Maintenance of Low-Cost Pour-Flush Waterseal Latrines in India.” Please see section 2.4.4 on Distance between 2 pits (pp. 7); section 2.4.8 on Water pollution aspects (pp. 8 ) and; Table 4 on pp. 10.

I think, the distances must be highlighted, when there is level difference, e,g., when latrine is uphill and a water well is downhill; and vice versa.

A paper on “Pit Latrines and Their Impacts on Groundwater Quality: A Systematic Review, by Jay P. Graham and Matthew L. Polizzotto,” (also attached), draws attention to nitrate, chloride and ammonia
(chemical contamination), as major contaminants of groundwater from latrines, due to their higher concentrations in excreta.

Whenever, I’m on a topic, like the one you have initiated, I’m always reminded of the proper platform for the handpumps on wells. Please highlight this briefly, as well. A RWSN publication on Platform Design is attached.

Smiles,

F H Mughal

F H Mughal (Mr.)
Karachi, Pakistan

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  • andreanick
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Re: Safer siting of sanitation systems : An introduction to criteria for risk reduction to groundwater quality

Dear Mr Mughal,

thanks a lot for taking part in this discussion and for your valuable input and references.

In our checklist which will be posted here tomorrow we direct he readers who are keen on knowing more about the topic to the Graham et al publication you have also linked to your post. Also we ask them to consider reading the ARGOSS manual and report by the British Geological Survey which is I think the standard on the onsite sanitation and groundwater protection issue at the moment.

I agree with you that pedestals are an important thing when talking about keping you wellwater safe. We have built in a figure on wellhead construction and sealing of annular space, but the pedestal might not be coming out as you wish. We will keep this in mind for a future version.

We have to make compromises between overall length of the document, depth of knowledge expected of the reader and mass of information that could be included.

So thank you again for the comments and be sure we thought about each of them.

All the best
Andrea
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  • andreanick
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Re: Safer siting of sanitation systems: An introduction to criteria for risk reduction to groundwater quality

Dear all,

the final version is now in the library as announced in this new thread:

forum.susana.org/forum/categories/64-wg-...f-sanitation-systems

You are welcome to use the new thread for you comments.

Thanks,
Andrea
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