Dear Gunilla,
Thanks for writing this paper. I am working on FSM planning processes and I have one more reference to convince that FSM is urgently needed especially since on-site sanitation is already widespread in India. 
I'd like to point to a modelling  study  which based on past  investment concludes that even in most optimistic scenario, most of Africa and Asia will not be connected to sewer systems by 2050.

I like the two measure you use - the build out rate and the rate of number of persons benefitting from the installation of infrastructure. These make projects comparable across geographies. I hope this leads to such data being maintained and also information of duration of various phases ( advocacy, planning, designing, procurement, construction, etc.) can be maintained for more projects to enable more research to understand where projects get most delayed.

I also like the surprise turn in the conclusion section where you discuss the need of changing curricula and training the future generations for appreciation of  alternatives to the conventional sewerage systems.  I completely agree and wish to point (though I have a hunch you already may be aware) out that some of it has already started. I am sure you are aware of the new masters course at UNESCO IHE. The NIUA  led some discussions in India and hopefully we will see a similar course tailored for India being offered at an Indian University soon. 

Regards
paresh

I would like to thank everyone who contributed to this discussion. The paper that we were working on has now been published. Elisabeth von Münch suggested I share it here on the forum to 'close the loop' - thanks Elisabeth for the suggestion!In writing this paper, we learned that there are very few official studies on the time and cost of building conventional sewer systems. We hope that our paper will inspire more studies to that end, as well as the sharing of data that can help make more solid predictions. Most of all, we hope our study will lead to increased funding and focus on finding realistic solutions.

www.mdpi.com/2071-1050/12/16/6518 ( Journal: Sustainability, Volume 12, Issue 16 )

Conventional Sewer Systems Are Too Time-Consuming, Costly and Inflexible to Meet the Challenges of the 21st Century

Gunilla Öberg ¹,* , Geneviève S. Metson² , Yusuke Kuwayama³ and Steven A. Conrad<sup>1

1</sup> Institute for Resources, Environment and Sustainability, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; This email address is being protected from spambots. You need JavaScript enabled to view it.
² Department of Physics, Chemistry and Biology (IFM), Linkoping University, 581-83 Linköping, Sweden; This email address is being protected from spambots. You need JavaScript enabled to view it.
³ Resources for the Future, Washington, DC 20036, USA; This email address is being protected from spambots. You need JavaScript enabled to view it.

* Correspondence: This email address is being protected from spambots. You need JavaScript enabled to view it.; Tel.: +1-604-306-9900

Received: 19 May 2020; Accepted: 3 August 2020; Published: 12 August 2020


Abstract: There is an urgent need for innovation in the sanitation sector because the conventional model (toilet-to-sewer-to-treatment) is too time-consuming and costly, and alternatives are lacking. We estimate the challenge ahead by developing scenarios for 60 of the fastest-growing urban conglomerates in the world. We find that the majority would need to build out their sewer systems at a rate that is ten to 50 times higher than the highest rate for any project in the World Bank’s database, which is unrealistic. We also carry out a case study of Lagos, Nigeria, which suggests that, in any given year, 14–37% of Lagos State’s budget would need to be invested to provide sanitation to the presently underserviced population while keeping up with population growth, which also is unrealistic. Our study provides clear evidence that the conventional model for sanitation is unworkable for rapidly growing urban areas. We conclude there is an urgent need to encourage and fund projects that promote innovations that can tackle the three core challenges: can be built sufficiently quickly, are flexible, and affordable. This is not likely to happen unless the future generation is systematically trained and educated to creatively support innovation in sustainable sanitation.

And another publication that should help Gunilla and others with this question about costs of conventional sewers versus other sanitation systems:

Daudey, L. (2018). The cost of urban sanitation solutions - a literature review. Journal of Water, Sanitation and Hygiene for Development, 08.2, doi: 10.2166/washdev.2017.058
www.susana.org/en/knowledge-hub/resource...library/details/3639
or washdev.iwaponline.com/content/early/201.../22/washdev.2017.058

I always find it hard to get my head around a methodology where people compare sewer systems with UDDTs. To me that makes no sense. The UDDT will always come out cheaper than the sewer system but it only does part of the job: it only deals with excreta whereas the sewer system deals with excreta plus greywater plus perhaps even wastewater from small industries. So how could this sensibly be compared?

I tried to find a solution for this in your paper and only found this which touches on this issue but does not really resolve it:

An option to undertake such analysis is to compare costs to the level of service provided by each sanitation system. A methodology to assess service level has for instance been designed by the IRC WASHCost initiative (Potter et al. 2010) and proposes a sanitation ladder comprising five levels of service (no service, limited, basic, improved and highly improved), based on four main criteria: accessibility, use, reliability and environmental protection. The authors suggest that a different ladder shall be assigned separately for excreta and urine management, for greywater, and for solid waste.

The author, Loïc Daudey, has probably addressed this in the paper elsewhere and I probably didn't grasp it fully yet.

Elisabeth

P.S. The paper inspired me to add a new heading on "costs" to the Wikipedia article on sanitation, see here:
en.wikipedia.org/wiki/Sanitation#Costs

Dear Gunilla and all,

I came across this presentation by Jeannette Laramee from Feb 2019 at the FSM5 Conference which I think you'll find very useful (if you haven't seen it yet):
Lifecycle cost comparison of fecal sludge and sewer based sanitation systems in India
fsm5.susana.org/images/FSM_Conference_Ma...CC-India.reduced.pdf

They used a very thorough methodology. As is to be expected, the cost per person goes down the more people are served by the sanitation system (this applies to the fecal sludge and the sewer based sanitation systems alike).

Who is behind this work:

This work was commissioned by the Sanitation Technology Platform (STeP)
and funded by the Bill and Melinda Gates Foundation, which supports the
development of transformative, non-sewered sanitation solutions. STeP derisks and accelerates novel sanitation solutions by connecting partners, facilitating field testing, and providing go-to-market support.
The Consortium for DEWATS Dissemination Society (CDD) carried out data
collection in India.

Regards,
Elisabeth

Dear All- Gunilla, Elizabeth, NityaJ, and others.

Having dealt with conventional natural process of sewage disposal system applying Dewats type of process for treatment of sewage and septage, wish to offr my comments on costing for capital - making of facility, maintainance daily and annually Etc..

The base design value for urban areas is taken of the flow data per day ... in kl/cbm per day at around 300-500 ppm BOD,
And if from poor or slum communities with lesser flush water at levels 1500-2500 ppm BOD.

In some OD areas, nght soil data is assessed accodingly for safe disposal.

Now we consider the base value of volume flow say 150 l gpcd per day per person, @ for 100px / 20 HH.. is 15000 l. ie 15 kl / cbm.

For natural primary process, at best it is done in sewer pipes, septic tanks, next for secondary process have baffle tnks with stone / pebble filters and in last- tertiary stage has phyto- remediaion using plants and greens.

Usually a HRT of 8 - 10 days is given.. ie for a day flow of 15 kl per day.
Total cubics or volumetriccally 15 0000 l, 150 kl/ cbm is held.

As a thumb rule for guidance have:
1. 5 -10% of 150 ML as pre process
2. 30% as primary- septic..
3.30% as scndry wth fltrs
4. 30% as tertiary wth plants Etc
5. 5-10% as polishing/ finishing process.

Accordingly the masonary work is progressed.. keeping say depth of each tank at 2-2.5m deep.
Exception phyto tank to be less at 1- 1.5 m ..
Hence surface land area can be assessed giving also working space kept at 50- 80% more.

Costing can be worked out applying the specs as given above vis a vis costs.. say at Delhi use Delhi Schedule of Rates..DSR.

For maintainance:
Daily ensure apt O & M practices. Electric power needed to draw out water for recirculation in phyto process and for re- use flow to community areas Etc.

6 mthly or annually each tank bottoms are excavated, filter stones flushed and cleaned
And all the matter is taken for co composting Etc.

Pipes are planned and fitted in each tanks for pulling out bottom sludges before implmntation of flows Etc.

Yearly the tanks are inspected any failure in structures are attended as required.

When re use water is used in communities , the gains to the extent of 50% cost of new water is realised.

With well wishes.
Prof Ajit Seshadri
Vels University. Chennai.

Hi Elisabeth,
Thanks for these tips. Very helpful!

best, Gunilla

Hi Gunilla,
After reading through your post again, some older discussions come to mind for me which might be useful for your literature research (maybe you already found them by searching through this forum):

There was a tool called WASHCost Calculator - we talked about it here:
forum.susana.org/forum/categories/164-fi...cost-calculator#2538
and here:
forum.susana.org/forum/categories/164-fi...proach-to-sanitation

Two interesting aspects from that:
- Make sure you don't just look at capital costs but also at the annual operation and maintenance costs (these can be high and difficult to finance for conventional treatment plants, e.g. for electricity costs of activated sludge plants). IRC was advocating using an LCA approach here (life cycle analysis).
- Make sure you compare systems that give you the same result. E.g. you cannot compare a sewer with a pit latrine because the sewer treats much more than just the excreta - it also takes greywater and possibly stormwater. The pit latrine plus fecal sludge managements only collects excreta, and sometimes only gives it partial treatment (so no wonder it's much cheaper).

Also Christoph Platzer from Brazil/Peru has posted quite a lot about the costs of dry sanitation versus conventional sanitation in the earlier years of the forum (2011 to 2015). If you put "Platzer" and "costs" into the search field you find some of his posts. E.g. I found this one which I think will be of relevance to you:
New sewage treatment plants in Indian cities: could dry toilets have been a viable alternative? - and Bengaluru wastewater reuse example
forum.susana.org/comparisons-of-various-...ewater-reuse-example

See also this paper that he authored in 2008:
Platzer, C., Hoffmann, H., Ticona, E. (2008). Alternatives to waterborne sanitation - a comparative study – limits and potentials. IRC Symposium: Sanitation for the urban poor - partnerships and governance, Delft, The Netherlands
www.susana.org/en/knowledge-hub/resource.../library/details/961

It's 11 years old now but I think the approach and methodology are still valid.

Please do let us know what you find and how you get on.

Regards,
Elisabeth

Dear Elisabeth,

Thank you for your thorough response, which made me realize that I did not sufficiently explain the background to my request. I am fully aware that a lot of people question the conventional sewer system as 'the gold standard' as there seems to be sufficient evidence to suggest that the linear-end-of-pipe solution (water toilet to sewer to treatment plant) is unfeasible particularly in rapidly growing urban areas because it is too inflexible, too costly and too slow to implement. Even so, governments and funding agencies such as the World Bank, hold it as the 'gold standard'. This is true pretty much across the world. For example, a recent paper suggests that 20 times more funding is made available in India for development of conventional sewer systems than for other potential solutions such as FSM (Hutchings et al., 2018). *

To give more weight to the argument that we need to find other solutions, we started to look for 'hard' numbers behind the claims that the conventional system is too slow, too inflexible and too costly for rapidly growing urban areas. We do have data from local consultants - what we are looking for is data from other locations, particularly under-serviced areas with high population growth, as this is where it intuitively feels as if it would be futile to invest in the conventional system.

Sorry for the 'jargon'. My understanding of these terms is that 'build-out-time' is the time it takes to 'build-out' the system from the work starts until the entire system is built. It is used in relation to the construction of conventional sewer systems (connections, sewers and treatment plant). The 'build-out-rate' is the time it takes per person or per household.

Looking forward to continued input and discussion about this topic

Gunilla

Refs

* Hutchings, P., Johns, M., Jornet, D., Scott, C., & Van den Bossche, Z. (2018). A systematic assessment of the pro-poor reach of development bank investments in urban sanitation. Journal of Water, Sanitation Hygiene for Development, 8(3), 402-414.
iwaponline.com/washdev/article/8/3/402/3...he-pro-poor-reach-of

Hi Gunilla,

I am not familiar with the term "build-out rates" or "build-out times". What do you mean with those? Also, I think it is problematic to generalise these statements about "gold standards" over the entire world. I think you need to distinguish what kind of countries or regions you are talking about. E.g. if it's Western Europe then true, sewers are the "gold standard" and more or less the only standard for cities (it can be different in remote rural areas). But when it comes to developing countries, it's a different story. Here it seems that the central business district might have sewers and perhaps some affluent areas - although even they might be on septic tanks if it was deemed at some point that there is enough space for septic tanks - and the rest is not connected to a sewer.

The new buzz word in any case is FSM - Fecal Sludge Management. See here on the forum: forum.susana.org/53-faecal-sludge-management
Nasir recently pointed out in this thread that FSM can co-exist with sewers: forum.susana.org/53-faecal-sludge-manage...-question-from-india

So it's not a matter of "one or the other", it can be a matter of both - depending on which part of the city has which needs.

Have you read some of the very good FSM publications that the Bill & Melinda Gates Foundation has put out? I think in there you would find some information on costs, also in relation to sewer systems. Take a look in the SuSanA library and search for BMGF (results: www.susana.org/en/knowledge-hub/resource...title=&author=&year=). Also we recently received publications by NIUA which you might find useful (NIUA is the National Institute of Urban Affairs). They talk a lot about fecal sludge and septage management: www.susana.org/en/knowledge-hub/resource...title=&author=&year=

With regards to costs of sewers, have you contacted any consultants in your town about this? Civil engineers with a few years exerience in the local water utility will be able to give you rule of thumb figures for their towns, e.g. X $ per km of sewer, or X $ per household to treat their wastewater at a treatment plant etc. And don't just look at capital costs. Often it's the ongoing O&M costs that will "break" a project in developing countries... Capital costs being financed by a donor, O & M costs not....

I wonder if you've browsed through these threads in the forum yet in the category of financing, tariffs and fees:
forum.susana.org/164-financing-taxes-tariffs-transfers

I hope some of this is helpful and let's continue the conversation!

Regards,
Elisabeth

Dear Rochelle,

Thank you for your advice. At this stage we are looking specifically for information about the costs and build-out times for centralized sewer systems. The reason being that this is commonly perceived as 'the gold standard'. Intuitively, it feels as if the conventional waterborne toilet-sewer-treatment plant solution is unrealistic in rapidly growing urban areas because it is too expensive, too slow and too inflexible. Many claim that this is the case, but we had not been able to find any 'hard data' on costs or build-out times for sewer systems and treatment plants, which is why I turned to SuSanA for advice.

many thanks,
Gunilla

Dear Ajit,
Thank you for your advice. We will keep those caveats in mind.
best,
Gunilla

Dear Gunilla.

The data given by Nitya is a convenient data to work out your estimate +/- 10%.

Also in local Indian scenario the work is semi labor- machine driven oriented. But a basis can be worked out.

Well wishes.
Prof Ajit Seshadri.