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UGD reforms: Rules & Regulations regarding Wet Well Implementation: Mangalore

The city of Mangalore has an existing UGD system where, in our zone sewage runs down to an old wet well  at a low point 'A', from where it is pumped to a STP located at a higher point for treatment. Similar is the case of other zones of the city.

With the increase in population and extension of the city the local administration recently ,decided to lay parallel sewage lines up to point 'A' in all zones. The plan was subsequently scrapped citing technical reasons associated with deep excavation, road cutting etc within the city.

 The present proposal which is being implemented, intends the additional sewage generated in the new areas to be carried to an intermediate point where a new wet well is built and through discharge line over the ground pumped down to point 'A' wet well. Similarly  about 22 new intermediate wet wells are proposed by the administration in different areas of the city and most of them are located in densely populated areas.

Knowing how poorly wet wells are generally maintained people in the vicinity of the proposed wet wells are protesting.

Here, I should like to seek your advice and guidance as to the following:

1. Are there any rules/ regulations/ standards to be followed when locating / maintaining sewage wet wells in a densely populated area?

2. How do administration of other growing cities with similar UGD system cope with the problem of additional sewage generated. Is the introduction of new intermediate wet wells in a densely populated area the only accepted strategy to avoid road cutting etc?

3. Is our local administration resorting to short cut methods by  going for intermediate wet wells(Pumping stations) or should it look for other alternatives?

Your advice would be appreciated.

Prakash Alva

alvakp@satyam.net.in

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Comments

1.

Dear Prakash Alva,

In good town planning principles and practices, the wet-wells, sewage- ponds and STPs are ideally located such that its functions do not affect other areas. And it is given at vast green-belts near flood-plains etc.
Usually STPs are planned with open areas sludge drying and handling areas for curing and maturing and solar ponds-drying sewage-slurry and all these are converted to usable manure and given to all municipal gardens. And the processed water is lead to the water-channels to be led down-stream. Then probably into river or river-streams.

Of course for conveyance of sewage from down-stream areas to STPs located in up-stream areas, SPS- Sewage Pumping Stations are provided.
The storm-water/ rain water drains are led separately with natural drainages to the reveries. But at most locations in urban cities, all these clean drains are used for conveyance of sewage and making all the areas polluted.

Rain-ponds en route are also polluted. ULBs are nonchalant on flouting all regulations. Once a clean dry drain becomes a wet-dirty drain- Nallah as locally called it stays so. Only PILs in court can get action, but it is pain-staking.

Our NGO has helped local bodies; RWAs take one such flow in an urban drain at Vasant-Vihar, New Delhi and converted into usable water for irrigating urban landscaping. Details are available in this website.

If only all urban waste-water can be duly converted to usable water for irrigation and lead down-stream then even farms down stream can get good water for irrigating for their agriculture.

Similarly all urban bio-wastes duly composted and transported as manure and for any waste-land development, sustainable solutions can be evolved and many problems solved.

With wellwishes from VigyanVijay,

Er. Ajit Seshadri
Head-Environmental Wing (NGO)
The Vigyan Vijay Foundation
New Delhi-110 045
http://www.vigyanvijay.org

2.

Generally STPs are located in relatively lower ground compared to the catchment from where sewage is conveyed. But if for some reasons certain parts of the catchments are at a lower level, intermediate sewage lifting stations (as you call it wet wells) are likely to be required for pumping the sewage.

Otherwise the manholes on the gravity sewer will be too deep thereby increasing the capital cost and complicating the O&M process. Now answers to the questions:

Q1. Are there any rules/ regulations/ standards to be followed when locating / maintaining sewage wet wells in a densely populated area?

No there is no general rule for locating wet wells/lifting stations. But commonly manhole depths are kept within 5-6 m. When manhole depth goes beyond that, Lifting stations are used to lift the sewage at a higher level and convey directly to another manhole/ pumping station or STP as required. But there is no general rules. Depending on the soil condition and location of the sewer line, higher or lower limit of depth may be adopted. Manholes of 10 m depths are also there in some parts of Western India, where soil condition is good.

There is no regulation for maintaining Lifting stations, but if it causes any environmental problem, like odour problem, overflow of sewage etc, you can complain to the nearby State Pollution Control Board office. They are likely to take necessary action.

2. How do administration of other growing cities with similar UGD system cope with the problem of additional sewage generated. Is the introduction of new intermediate wet wells in a densely populated area the only accepted strategy to avoid road cutting etc?

Too generalised question. It depends on a lot of issues like location of STP, possible alignment of of new sewers etc. etc

The concept your municipality is adopting is a centralised sewage treatment system.

But there are other alternatives like decentralised system. A number of small package sewage treament plants can be contructed to treat the sewage locally instead of conveying it upto a centralised STP. But again this is only a possibility. Such decentralised plants depends on availability of land and capital investment and ability to maintain a considerable work force for operation and maintenance.

This concept has been successfully used by Delhi Jal Board and package treatment plants performs well. An 1.5 -2 MLD plant can be accommodated in 20- m x 20 m area within a cost of say 1.5 - 2.0 crore. This can give you some idea about the amount of cost and land requirement.

3. Is our local administration resorting to short cut methods by going for intermediate wet wells(Pumping stations) or should it look for other alternatives?

Hopefully the administration has considerably knowledgeable experts and they must have taken advise from good consultancy firms. So it will be too presumptious to assume that they are not doing their job properly. Engineering is not a political movement. So instead of being hostile to the administration, it is better to request them for clearing your doubts and convey them your concerns.

3.

Thank you both Mr.Sheshadri and Mr. Chowdhury. Your answers have been helpful and informative.

In reference to Mr Chowdury.s reply to my question, I should like to put some clarity to the situation mentioned by me . The administration project work is carried out by an agency Karnataka Urban Infrastructure development and finance corporation (KUIDFC) . This government agency had engaged a reputed consultant firm, M/S DALAL CONSULTANTS, who made an exhaustive study of the existing gravity sewage system running at a maximum depth of up to 6meteres with details of restrictive manholes/ lines and also projected the sewage system requirement until year 2026 as well as drew the hydraulic design for the entire city.

They advised rehabilitation of the existing partially choked sewer line and manholes as required and laying new lines for additional sewage. Accordingly new pipes were procured and and lined up along the roads (2004). After a gap of about an year suddenly the KUIDFC engineers modified this advice and introduced proposal of intermediate wet well(pumping station), instead of rehabilitation of old lines citing reasons like zig zagging of road,narrowness of the road ( 30 feet)making trenching difficult .

It is in this background we had to suspect the competency of the administration and as the administration was hostile had to resort this forum to get better insight to the problem. Even the concept of decentralised mini STP's for additional areas or pockets were also suggested but the response were not positive .

Thanks and regards

Prakash Alva

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