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Storm Water Drain (SWD) Muck / Mud Traps

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 “In most countries, sieve/meshes only hold back items which are too big to clog the drains. It is hard to stop mud from entering drains using meshes.”              - IDS

It may not be harder than clearing huge amount of mud collected over the years in these SWD. What is required is a small civil engineering design exercise, to obtain a solution to the above challenging problem. I accept that to brush aside something because of a small apparent problem is a human tendency.

However I also believe that necessity is the mother of invention.

 It was JDS Chief Minister HD Kumarswamy who spear headed the much talked about BTRAC roads, at the time of execution. The covered ducts leading the storm water from the BTRAC roads to the road side SWD do have muck traps.

True Mesh / Sieve idea may not work when it comes to dealing with mud being washed away by storm water from the roads.

It has to be trapped by providing deep receptacle in each road side duct. The mud is supposed to be trapped by this receptacle which is nothing but a deeper rectangular hole in the duct. Trapping this mud at the entry level is the key to the solution. [Another example is our ordinary commode with U shape exit trap]

 Some of the important points however are 

1.      These traps are covered. Hence it is not possible to know when the traps are full.

2.      So, there should be a maintenance schedule for periodic cleaning of the traps.

3.      When the design is not perfect / satisfactory there should be a continuous review and parallel research.

4.      The will to find better solutions is the key. 

5.      We need to think ab initio avoiding the trap / awe of what is there abroad.

High time we should move ahead of what is there in developed countries.

 If sieves meshes cannot do the job, think of the alternative:- 

  1. Trap the mud at each duct feeding the main SWD
  2. Periodically clean the duct traps.
  3. It is foolish to clean the big SWD on a yearly cycle as it is the practice now. 

It is only unfortunate that people in power may not be too enthusiastic about problem solving.

Are the problems themselves important in their survival?


RKCHARI's picture

Dear PSA Saar, Ah, but you

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Dear PSA Saar,

Ah, but you missed the most important aspect of it being "high time we should move ahead of what is there in developed countries" !

Could you add a 4th point about seeking an entirely different solution of covered SW drains or rather point of source infiltration systems?

There really is no need for trapping the mud at each duct feeding the main SWD or periodically cleaning the duct traps or cleaning the larger SWD annually. In one fell sweep all these festering problems can be solved by getting rid of open drains altogether!

I am amazed that the authorities who occupy the decision making chairs in BBMP / BWSSB are wondering whether it is worth taking a stand on implementing closed infiltration systems in place of open drains. Where is the question of any doubt? Closed infiltration systems are working without a hitch in over 200,000 kilometres where we have intervened in 30 countries worldwide.

Is mother earth different in its basic properties of being able to infiltrate water (albeit at different speeds of infiltration depending on nature of soil) or is rainwater more viscose in India than in Western countries?

The doubting Thomases in a desparate bid to thwart anything new then turn to infiltration systems being more expensive. But have they done any cost benefit analysis? Does it not make sense to spend on a solution now and rest in peace for 50 years or more instead of paying petty amounts over any number of years and facing the continued wrath of public? And if the solution is being offered on turnkey basis and to boot on BOOT basis(pun intended), why do the authorities wish to behave like ostriches?

I wonder when Namma Bengaluru will think out of the box and take some really drastic steps "for better or for worse till the next elections do them part"!




Naveen's picture

SWDs - Incorrect assumptions

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Your assumption that a weir arrangement (similar to traps in toilets) would successfully trap all mud is incorrect. Only heavier particles in the mud will sink & get trapped, whilst most of it will emulsify & flow with water & remain at the bottoms of SWDs when water evaporates even if such deeper traps are provided. The traps will only help in minimizing accumulation of all mud in SWDs, at best. Thus, the problem will remain, but to a somewhat reduced extent with the deeper entry points.



I am beginning to see the benefits of the system that you demonstrated & spoke of. However, until we are sure that our streets are not going to be tampered with (for laying all kinds of pipes, cables, etc.), I don't think we should take it up. When we are more or less certain that infrastructure such as drainage, water /electricity /telephone /OFC cabling are complete & that no more road widening is anticipated, we could try the system.

Why I say this is because there is still a lot of "fire-fighting" that remains to be done. When compared with other developing cities, we are still to address more pressing issues such as improvement in PTs, reduction of traffic, elimination of autos, 2-wheelers, good pedestrian infrastructure, etc. If we start laying plastic crates below ground, they will be uprooted several times repeatedly when various works are undertaken, & result in wastefullness.

Some streets in CBDs can however be tested with the system to check suitability.


psaram42's picture

RWH VS Infiltration in situ

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 @ Chari sir 

Per haps Open / Closed Drains which transport nature’s clean / pure rain water from point A to point B belong to RWH category. Over and above RWH for immediate requirement of potable water, the remaining Rain Water can be infiltrated in situ. Maintaining a respectable ground water table is also important I believe. At this point we keep the discussion to RWH aspects. 

@ Naveen 

I was not assuming at any point that I had any kind of solution to propose. On the other hand it was only for making a point that there is a need to ideate. If you see the amount of mud removed at date at the 12th main Indiranagar SWD it is equivalent of the whole volume of the drain itself. I hope there is a way to get a solution to the problem of separating it from affecting the whole system of drains rather than restricting the problem at the entry ducts themselves. I have a feeling it is a worth while problem to investigate by concerned experts. 

The point which is undisputable is the present state of affairs as far as working of the BWSSB is concerned.  



idontspam's picture


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psaram42's picture

A Nice example Indeed

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 Hi IDS,

That is a nice example. Wish we could benefit by some lucid explanations, too. Why the tweets?



RKCHARI's picture


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PSA Saar,

Storm Water Infiltration system that I propogate can easily be converted to Rainwater Harvesting Systems by wrapping retention tanks with impermeable liner. SW can either be retained for re-use or infiltrated for re-charging groundwater table. So the question of covered SW only when we need to re-use it as RWH system is not necessarliy so.

I am recommending closed infiltration system in preference to open drains (notice the Oxford Dictionary describes the word "infiltration" as purifying process and the word "drainage" as wasting away) in all instances irrespective of the fact that it is more politic to bat for both systems to co-exist so that the pro-open drains campaigners don't feel we are treading on their toes!

Naveen Saar,

Firstly the infiltration tanks we are recommending placing underground, duly covered are at least 300 to 500 mm below ground covered with drainage cells, sand, soil and a host of other natural filtration mediums. Moreover, the end product will also be covered with porous bitumen or asphalt which will make the installation virtually tamper prooof. So unless one is dealing with vandals who are hell bent on destroying a normal installation meant for the benefit of citizenry, I personally do not think they will be tampered with. If it were so, why have vandals not stolen co-axial cables, concrete drain-pipes and BSNL cables that are lying underground?

Secondly, even if we presume our hapless retention tanks made of recycled polypropolyne is tampered with, because of its modular nature, we can easily replace it literally within minutes. The stolen tank unit is literally of no use to the guy who steals it as its very design being of a matrix nature will render it useless as a storage bin for the guy who steals it!

Thirdly, regarding sorting out the various cables and pipelines already criss-crossing underneath that we would need to take care of before installing our underground tanks, this is exactly our expertise. We have developed proprietory software to handle such complexities of installation and we will ensure everything remains undisturbed while installing our tanks. Once installed and if cables lying beneath or beside tanks require to be accessed, it can easily be done as our tanks simply unclip when required and after repairing the cables they can once again be clipped on!

I hope my detailed defence of closed drains does not end up being an unabashed promotion of our technology. I am only trying to point out the common misconceptions.

Warm regards,




Naveen's picture

Vandalization was not the issue

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Chari Sir,

I didn't mean vandals when I said tampering - please recheck my post. I was referring to the unending digging that has been going on & on to lay pipes, cables, widening, etc. The infrastructure being unable to cope with demands, it will continue to remain over-loaded with the result that road digging is not going to end any time soon.

With the need to keep digging again & again for various reasons, I feel it's early days to invest in the system proposed by you. Once some stability or optimum conditions have been reached with development of infrastructure, it will make sense to consider it since with each digging, the crates will have to be removed & refitted & might actually pose obstacles to install cables, pipes, road-widening, etc.


psaram42's picture

I need to explain.

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 This thread is a continuation of my earlier thread “Early bird offer - SWD Cleaning”. The reason that I did this was to separate the trapping of mud to the individual smaller ducts feeding the main SWD discussions. If one refers to the comment in the earlier thread. The present technology being followed by our BWSSB is 2500 years old Roman Technology. I wanted to avoid referring to new technologies purposely because I did want to restrict the discussions to the currently adopted technology.  The specific reason was to avoid referring to new technologies at least in this thread, let alone promote them. It is obvious that there is no purpose in promoting new technology if there are simple solutions to do same quality work with old technology itself. If not what stops for a demand for a better technology?

psaram42's picture

SWD Open or closed

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 Open storm water drain is a closed chapter as far as [I am] BWSSB is concerned. The reason being the following chain reaction:- 

  1. open drain attracts garbage
  2. People seeing the garbage in the drain use it for urinating.
  3. The drain will not be cleaned by sweepers
  4. More garbage
  5. the drain gets Clogged
  6. During rainy season mud gets collected in free drain spaces.
  7. If the Drains are closed in variably a few slabs are kept open 

This is the mechanism how it happened at 12th main Indiranagar. The solution is:- 

  1. BWSSB should make up there mind to have all smaller open drains completely closed.
  2. No slabs should be allowed to be removed, without immediately closing it
  3. Why not have simple large diameter RCC Pipes, instead of the present rectangular granite slab lined system? 

Here is what BWSSB done recently to prevent garbage being dumped in Rajacauluveys:-


 Picture 1. Miranda School Rajacauluve Fense. 




 Picture 2. Miranda School Rajacauluvey No Fence side on JB Nagar Main Rd. 

Kindly obseve the Garbage at Pic-1 is safely kept out of the drain, where as at Pic-2 it is dumped inside the drain.

Kudos to BWSSB! After all they have recognized the problem and offered a solution that works!

sanjayv's picture

Storm Water Drain is BBMP and not BWSSB

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 Just to clarify the "para-statal" mess that we have.  BWSSB is responsible for sewage.  Storm Water is BBMP.  Repeat after me... BWSSB- sewage, BBMP-storm water. .  What a mess, literally as well as figuratively.

psaram42's picture

True Sanjay

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You made me nervous!! 

 BBMP comes under BWSSB. Since we are planning to meet the BWSSB Chairman at present, we don’t consider BBMP for the time being. We are following Top down approach at the moment.

Later we plan bottom up approach. One or two cycles we will be through!!!

By the way the water tank at Jeevan Bima Nagar person where we pay water bill is Under Cauvery Bhavan BWSSB not BBMP. Please check your water bill for instance. You will notice it is under BWSSB. Not BBMP. [I checked my water bill right now] 

Thanks any way.


idontspam's picture

Closed SWD

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  1. BWSSB should make up there mind to have all smaller open drains completely closed.
  2. Why not have simple large diameter RCC Pipes, instead of the present rectangular granite slab lined system? 

2 very good points. While Rajakaluves remain open there is no reason to have street side storm water drains open. They attract dumping. The only outlets on local streets should look like the below.

idontspam's picture

 BBMP comes under

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 BBMP comes under BWSSB

Really? How?

sanjayv's picture

BBMP and BWSSB are two separate bodies

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PSA sir,

BBMP is responsible for storm water drains, BWSSB for sewage lines and treatment. BBMP does not come under BWSSB or vice versa.  Only difference is that once elections happen, BBMP will be run by an elected body answerable to Bangalore's citizens. BWSSB is run by the state, answerable to the people of the state through legislators.

RKCHARI's picture

Large Dia RCC Pipes

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Large diameter RCC Pipes instead of open drains would not solve the problem as: 

a) Storm water would not be able to enter the pipes from the gutters on the shoulders and if you make holes on the pipes, they will end up being open drains once again;

b) Storm water will still require to be carried from one place to another which is absolutely unnecessary;

c) Storm water cannot be re-used for even watering plants on verge and sides.

Just my two penny worth.



n's picture

BBMP, BWSSB and open drains

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At psaram42 - regarding SWD open drain or closed:

BWSSB - water storage, treatment and distribution, wastewater collection and treatment. Water bill by BWSSB (includes sewage charge; don't know if it includes rainwater charge)
BBMP - storm (or rain) water collection and disposal, maintenance of some lakes.
See BBMP gyan and BWSSP gyan.  (BTW at sanjayv - it is hard to find the gyan with a simple BWSSB gyan search or even under first page in gyan - probably best to have it easily accessible. Maybe permanent link to gyan of respective topic at the top location of that topic's discussion can be provided. Oh! I see the issue - the topic tags BWSSB in full and abbreviated form are missing and hence don't show up on search - I cannot edit or fix it).

One important disadvantage even with meshed rajakaluves is the downstream encroachment that contributes greatly to the flooding. They keep happening in spite of regular clearance drives. Sometimes, people go to court ...

sanjayv's picture

fixed it

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 THanks for pointing out n.  I fixed the tags on the gyan.

psaram42's picture


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 What is BBMP? 

Mahatma Gandhi had Gram Panchayat at his heart. Importance of Gram Panchayat raj was recognized by the British very well. After independence theAdministrative structure of India is based on local bodies like Gram Panchayats and Municipalities / Municipal corporations. Each village is supposed to have a gram Panchayat. Thus BBMP is a Municipal Corporation.

The gram Panchayat, so close to the Mahatmas heart is given a go by our current BJP government.  T Subbabhatta has given a masterly focus on the bane of BJP raj wrt our city of Bangalore.  

The Municipal Corporation of Bangalore ie BBMP commissioner Meena reports to the secretary Mr. Ramamohan who is the chairman of BWSSB. [ I am unable to get the hierarchy chart right now. Will try and give it later ] 

However if the mayor was to be elected soon, the situation might have been different.

idontspam's picture

Usage of dumpsters

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 Major percentage of drain clogging muck is caused by dumping of construction debris. It is unfortunate that sidewalks are used for dumping debris and construction material which go uncleared and block drains.

It is incumbent on BBMP to mandate the use of Dumpsters in front o the construction site which can be towed/trucked away. 

RKCHARI's picture

Brilliant Suggestion

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Dear IDS,

I think this is a brilliant suggestion and requires wide publicity through media. All Property Developers should be given strict rules to follow this idea of keeping building debris in Dumpsters.





blrpraj's picture

re: brilliant suggestion

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"I think this is a brilliant suggestion and requires wide publicity through media. All Property Developers should be given strict rules to follow this idea of keeping building debris in Dumpsters."

I could not help smile to myself. This suggestion which is brilliant to us Indians is basic commonsense in most developed countries ,  amazing isn't it given the fact that we are the silicon valley this side of the globe?  I think what would be more effective than media coverage is regulations (as suggested by you) that mandate construction debris be held in containers as shown in one of the photos above AND those rules should be strictly enforced. Otherwise, just by media coverage nothing is going to happen. Let's say I was building a house and violation of  construction material dumping rules resulted in a stiff fine of  say Rs 25,000 or something like that (failure in payment resulting in withdrawal of construction permit followed by demolition) then would I be doing that? Every bad action should result in  consequences and punishment, all of us pretty much know that we can get away with dumping construction material on the road in bangalore and that is the problem.

I may not be surprised if there is some rule somewhere in india that says garbage and other debris should not be dumped in public places...who cares anyway and who enforces it?

blrsri's picture

dumpster issue

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btw why do we not have dumpsters for garbage and we use mobile 3 wheelers for collecting garbage instead?

thats because we have too much poverty around us..there is a threat of the dumpster being stolen and either broken down to pieces and sold for food or converted to a roof of some poor family in a slum! comment guidelines

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