Earlier System of Sewage Farming

 

Prior to commission of the new sewage treatment plant, raw sewage was directly pumped for irrigation purposes in the nearby vicinity.  Quantity of sewage diverted through the channel was 45 MLD. Although it was not desirable to utilize raw sewage directly for irrigation, farmers used it for years together and fortunately there was no epidemic. 

 

There is a distribution chamber on the eastern side of STP. Two small canals are leading from the distribution chamber; one goes to the left direction and another to the right direction.  Area available for irrigation was 750 hectare (Ha). However, it could irrigate only 487 Ha after accounting for the losses due to water theft or overflow. Benefited villages were, Bhandewadi, Kharbi, Wathoda, Bahadura, Bidgaon, Jinsi, Tarodi(Kh), Tarodi(Bk). Farmers were charged water cess at anominal rate of Rs 534/Ha/year, as against prevalent water cess of Rs 4,625/Ha/year as per the norms laid down by the Government of Maharashtra. Revenue collected by the Nagpur Municipal Corporation (NMC) on account of water cess was only Rs. 2 lakh as against assessed revenue of Rs 2.6 lakhs. NMC also used to lift water for irrigating a land of 40.12Ha. Development of area under NMC was covered by paragrass. Revenue earned from the sale of paragrass through public auction was Rs.5 lakhs. Thus, total revenue generated was only Rs 7 lakhs as against recurring yearly expenditure of Rs 60 lakhs. Economic un-viability of this scheme can be traced to the very low water cess fixed by the NMC on one hand. On the other hand efficiency of pumping machinery was also reduced due to poor maintenance resulting into high-energy charges. Thus, raw sewage was not disposed off properly and moreover, the system of maintaining it was costly too. Therefore, there is an urgency to dispose off effluent properly.

 

Proposed System of Utilization of Treated Effluent

 

Previous experience of running the scheme of sewage farming was found uneconomical. So, currently entire 95 MLD treated effluent is being discharged into the Nag river. Due to this, on one hand farmers which enjoyed abundant water (even though polluted waste water) for their farming, can not now get the much wanted water for irrigation, while on another hand the corporation has lost revenue from irrigation cess which is needed to make the system economically viable.

 

As farmers are deprived off the water for irrigation, there was hue and cry and they also agitated for this cause. The issue of reuse of effluent from STP was given a thought at the various forums. It was suggested that the scheme could be implemented by the Irrigation Department, MJP or NMC. The scheme could be operated and maintained through the proposed co-operative society of the farmers. It is expected to get funds from Vidarbha Statutory Development Board for implementation of this scheme.  The proposed scheme, if implemented, can enhance the irrigation potential to the tune of about 1212 Ha and NMC could get Rs 70 lakhs of revenue towards water cess from beneficiaries.            

 

STP releases water at the elevation of 295.48 m. Based on the topography of the command area, the system can be broadly classified into two categories: (a) pumping scheme and (b) the gravity scheme. Schematic diagram of proposed treated effluent scheme is shown in following Figure.

 

 

(a) Pumping scheme: Earlier, NMC used to irrigate 487 Ha area, out of which 337 hectares area is at higher altitude and hence, it requires lifting of treated effluent for irrigation. Remaining 150 hectares will be irrigated by means of a gravity scheme. It is suggested to irrigate area on higher altitude by pumping and its water requirement is about 25 MLD. For pumping proposal, estimated capital cost is Rs 44 lakhs. The scheme envisages the works as shown in following Table.

 

Envisaged works in pumping scheme.

 

Sub work

Cost Rs. Lakh

1. Construction of Sump & Pump house                                                         (520 m3 capacity, 30 min detention period)

20.30

2. Pumping machinery, 30 BHP, 3 Nos.                    (50% standby) Q=145 lit/sec, Head=10 m

14.50

3. Power connection charges

5.00

4. Escalation & others

3.98

Total:

43.78, Say 44

 

Cost of maintenance and repairs for the pumping scheme for 4 months period will be around 8.87 lakhs.

 

(b) Gravity scheme:  It is proposed to irrigate 875 hectare of land which includes overlapping area of 150 hectare of earlier sewage farming pumping scheme in addition to new command area of 725 hectare. Estimated cost of the project is Rs. 352 lakhs. Principal features of this scheme are summarized in following table.

 

Principal features of gravity scheme.

 

Particulars

Cost (Rs.Lakhs)

1. Collection chamber1.8x1.8x5.45 m near terminal chamber of new plant and 450m long gravity main of 1000 mm, RCC NP-2, from collection chamber to distribution chamber

40.07

2. Main Canal 2100 meter long and distributaries

133.07

3. Land acquisition miscellaneous

129.71

4. ETP charges

48.39

Total:

351.24 say 352

 

 


                                                                                   

                                                                               

                                                                                                                

 

 

                                                                                                                      

                                                                                                                        

 

   

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

M&R cost of the project is Rs. 28.30 lakh and benefit cost ratio works out to 23.34. Villages benefited will be Bidgaon, Adka, Khedi, Tarodi (Kh), Tarodi (Bk), Pandhurna, Temasana, Dighori (Bk).

 

To execute the above-mentioned project, following points should be considered:

 

1.     It is essential to obtain funds from the Vidarbha Statutory Development Board to cover the construction costs of the project.

 

2.     It is essential to resolve the problem of acquisition of land being.

 

3.     It would be suitable to maintain the proposed project through co-operative society of farmers, because the society would be able to raise funds required for repair and maintenance purposes. Besides this, if the project is executed through the society, concessions in power and electricity can be availed as per the government rules, which will ensure a decrease in repair and maintenance costs.

 

4.  NMC’s consent is necessary for releasing treated effluent for irrigation.