Drainage Vis A Vis Soak Pit System - Answer To Modi'S Call
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Drainage vis a vis Soak pit system - answer to Modi's call

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See interview of Ashok  Kothare

British people introduced drainage system in Mumbai in nineteenth century. Prior to that we had age old soak pit system to dispose of human waste. Drainage system was possible in this city in those days because for the first time we had a properly developed water supply by pipes in this city. That water was probably potable and used for all domestic requirements. A tank is constructed on top of the house to collect water coming from the mains water pipes and by an elaborate inner pipe system that water was supplied to toilets, bathrooms and kitchen. On the other side in toilet a commode is provided so that a person may sit properly and do the nature's call. The deposited feces would be drained out from the commode into a pipe line ending in an inspection box at the ground. Drainage pipe would further extend and finally join the main drainage pipe system of the city. In this way, human waste was collected by the pressure of water from tanks and it was pushed by that water to move further. In this way feces from all houses was carried away to a place where it was thrown in the sea. Sea was the final destination for all feces from the city of Mumbai. This I am talking about Mumbai, in other places we see that this sewerage water is dumped in some river or lake nearby. Mostly without any sewer treatment plant to purify it so that it can be introduced without any hazards. This practice of dumping sewer in rivers and lakes has already spoiled many of our rivers and other water sources. Recently our new PM has expressed desire to save Ganga river from sewerage pollution.

Success of this system was dependent on copious supply of water from lakes and dams in the vicinity. City Municipal Corporation had made elaborate regulations to guide, about how the system should work successfully. According to that 150 gallons of water was supposed to be available for each citizen per day of this city in those days. Flushing tanks were available near the commode to supply gushing water supply to push the feces in the pipe called gutters in Mumbai language. At a given time 5 gallons of water was forcibly pushed into the commode to push the waste. In addition to this water there was other water coming from kitchens, bathrooms, wash basins and together this water successfully carried away human waste up to the sea where that was disposed off into the sea waters. That was considered as the final destination for that waste material. As we see per person 150 gallons were made available it worked well. That was good enough quantity of water to push waste from houses through the drainage pipes into the sea. This drainage system worked well and it replaced other human waste disposal arrangements those were in practice such as soak pit toilets and toilets with septic tanks. Drainage system proved to be very clean and most hygienic as compared with other prevalent options. British wanted to impress their Indian subject with their novelties such as Steam Engine and Trains and horse drawn Buses; drainage system added to that as the most sophisticated system.

However, things did not stay that perfect in the later period. As population of this city grew less water was available per person. This quantity has been reduced to 45 liters per person per day. That means, just about 9 gallons per day. This alarming reduction in water supply per person has reflected very badly on this drainage system. Due to this reduced supply of over all water supply to city; this drainage system has failed but nobody bothers to take any serious note of this situation. What happens because there is not enough water to push this waste? We must see so that we may be able to understand why we have many problems of hygiene.

Before we take this subject further, I want my readers to understand other system that was prevalent in our country; it is called soak pit. This is a very simple and very practical system developed to utilize nature's treatment of waste. Nature's treatment of waste is based on microbes. These microbes attack all wastes and duly convert it into manure. Particularly human waste is the most adapt for this treatment because human feces decomposes within 24 hours and completely destroyed into black soil. In soak pit a tank or pit is prepared under the commode so that it has all four sides properly tiled to give it lateral strength and the pit or tank does not cave in due to pressures of earth surrounding that pit. However, the bottom is left open to ground soil. This arrangement makes it possible for the feces to deposit on the ground soil where the extra water with it is soaked in the ground leaving only waste to decompose. From that action of ground soil to soak the water it got the name soak pit.

British had introduced another system called septic tank. In that the pit or tank is tiled all over that means, even the bottom is tiled and made water tight so that no water can be soaked in the ground. In this system nature's treatment is not utilized fully. Water and feces and other waste products due to human life activities remains collected in that pit. The feces decomposes anaerobically, that is why it is called septic tank system, giving out obnoxious gases due to sulfur and phosphorous in that feces. This system is not as natural as the soak pit but gives an opportunity to do some business out of it. We see that all western modern developments are having a business angle. Drainage system gave British a big business of supplying galvanized steel pipes manufactured in England and enormous business of supplying large size Cast Iron drainage pipes to carry sewer to the sea. All material was imported from Briton and they made big profits out of that. I have to mention that angle because it explains why British preferred first septic tank and later on drainage system in place of a better and more natural soak pit system but lacked the capacity to give any business opportunity to British rulers. All for business, after all they had come here to earn out of our markets. Let us not go into that discussion further.

Let us now switch over to our discussion about what happens in our drainage pipes because there is not enough water to push the load of waste into the main drainage system of the city. Feces remains in the gutters right under the building and continues to rot there similarly to septic tank while insufficient water runs over it and goes into the main gutter pipes of drainage system. Poisonous gases emitted out of rotting feces, we often get the feel of it at ground level during nights if went pipes are not fitted. Even so we seldom bother about from where it comes and brush it aside as a not so important a topic. This rotting material attracts many germs, insects and bigger marsupials such as rats and bandicoots. Occasionally, they travel through the pipeline of the building and reach in your toilets and through that into your house. These marsupials in abundant numbers are living in our city main gutters and from there they spread all over. Therefore, we should be careful of this situation. Silently, this rotting feces invites many diseases. The potential danger of this situation we should not neglects. These marsupials is a big problem for our Municipality. They are spending in lacks to eradicate them but since their source is in the drainage pipes they cannot be eradicated by any means. These marsupials is one more bad side effect of drainage system. Our cities are now infected by many diseases, the root cause is right under your house, the inefficient drainage system.

After careful extensive investigative research I came to the conclusion that we should switch over to our age-old soak pit system because our municipal corporation is not in a position to provide the quantity of abundant water required to make drainage system work efficiently.

Before I conclude on this topic I want to share some statistics, those may interest some readers who may be interested in knowing more about the reasons why I prefer soak pit over drainage system.

  • Drainage system needs additional provision (Capital intensive) for purifying sewer so that it can be introduced into the other water systems. As such very often no treatment is given on this sewerage and allowed to enter large water bodies, creating pollution problems. No such provision is required by soak pit.

  • Drainage system itself is capital intensive, soak pit is not.

  • Drainage system harbors insects, germs and marsupials who are risk factors in the city life. Soak pit does not cause growth of these and so is far more risk free.

  • Drainage system does not help ground water improvement. Here we should note that soaked water has some BOD (50 to 200) value which is reduced by the microbes in the ground. The soaked water travels through the ground and while traveling gets purified by these microbes and oxygen in the soil, and after about travel of 80 meters that water is almost cleaned (BOD, 20), suitable for agriculture. Therefore, soak pit helps ground water conditions to improve. This puts a limit on where we should have a surface level well or tube well. Well should be about 100 meters away from where we have soak pit.

 Other statistics are, soak pit size should be calculated on the basis that 4 square foot bottom size of the pit per head, Maximum depth 3 meters (10ft.) minimum 2 (6ft.) meters. All the drainage pipes of the building will end in the soak pit at upper level protruding into the tank, pouring the waste water in the tank. Rest is taken care of by nature. Soak pit tank will have an inspection chamber cover and went pipe of suitable height. I hope our Municipal authorities will give this subject required attention.

Example to understand above given statistics, a building has 30 heads staying, so a soak pit tank of size 30x4= 120 sq.ft bottom and depth 10 feet, is required. Interesting part in this is that, if tank is built properly there is no further maintenance cost on this system. Each house will have its own soak pit tank. To keep percolation rate safe so that microbes do not become disfunction distance between any two immediate soak pits will be not less than 30 to 40 feet.

Recently Modi proposed to take up, up hill task of cleansing Ganga River. Statistics shows that over all 87% pollution is caused by sewerage water from human habitat. If soak pit method is introduced in Varanasi so that no soak pit is situated near the river bank, keeping distance at least 100 meter away from the banks of river; Mother Ganga will be clean by no time. As all soak pits will be constructed by respective building owners, actual cost to the government will be nil. For that local municipal body should give some help to owners so that in record time all soak pit tanks are ready. If they really do it Mother Ganga will be clean without much hassles. I hope Z News people look to this and implement it.

Varanasi will be first to implement this age-old sewerage system anew and abolish drainage system from that city. I request my readers to ask them to read this so that they will know how easy it is to stop pollution in, not only Ganga, but all rivers and lakes who are being polluted due to this drainage system. However, there is a small group of vested interest who are likely to create trouble in implementing this change. I hope all nature lovers will support it.


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