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Tuesday , 19th October 2021
Section: Major Water Supply Schemes pages are not under access control

Underground Sewerage Scheme to Velankanni Town Panchayat in Nagapattinam District Under Amrut Programme.

Quantity :

Int 2.33 MLD, Ult -2.66 MLD

Cost of Installation :

Rs. 33.51 Crores

The Government of Tamil Nadu vide G.O (D) No. 24 /MA & WS (TP 2 ) dated 17-01-2013 for Rs 23.89 Crores .Revised Administrative sanction GO Ms. No.G.O(D) No:18 / MA &WS (TP2) Dept dated: 27.01.2017 for Rs 33.51 Crores

 Prefatory :

As per the directions from Government, the Tamil Nadu Water Supply and Drainage Board (TWAD Board) has undertook the investigation works and preparation of Detailed Project Report (DPR) for providing Underground Sewerage Scheme for Velankanni Special grade Town panchayat in Nagapattinam District during 7/2011. Velankanni Town Panchayat is not provided with underground sewerage system. The town is provided with open drains in the main area of the town and septic tanks.

Necessity of the Scheme

The existing open drain system is not functioning satisfactorily. The water is stagnating in many places and due to that mosquitoes and flies are developed, which cause health hazards. In order to improve the hygienic conditions, underground sewerage system is a must for Velankanni Town Panchayat.

Population and Projection

In designing sewerage system for any town the important factor is the present population and its expected rate of growth. The concept of the base year 2018 is considered for projecting the intermediate population for 2033 (15 years from base year) and the ultimate population for 2048 (30 years from base year).

Design Population

Year Population
Base year 2018 13000
Intermediate Year 2033 16000
Ultimate Year 2048 19000

Detailed Description of Proposal

The proposed UGSS Scheme is designed for the ultimate stage i.e. year 2048.

The Sewerage work is divided into the following five categories and described subsequently.

  • House connections and local sewerage.
  • Main and trunk sewers.
  • Pumping station.
  • Pumping main.
  • Sewage Treatment plant.

House Connection and Local Sewerage Including Branch Sewers

The total number of house service connections calculated as 2280 Nos. The Velankanni town panchayat is divided into two parts in east-west directions for UGSS purpose, the western side is termed as Zone I and the Eastern side is termed as Zone II and Zone II A.

House Service Connection Details

HSC Zone I Zone II & Zone II A Total
Domestic-110 UPVC 565 1411 1976
Commercial – 160 UPVC 4 300 304
Total 569 1711 2280

Main And Trunk Sewers

The total main and trunk sewer covers a total stretch of 19918 m and total manholes of 714 Nos and 2Nos of Lift manholes.

Sewer line Details

S.No Size of Pipe Zone I Zone II Zone II A
1 160 mm UPVC 1295 m    
2 200 mm UPVC 6389 m 10195 m 313 m
3 250 mm UPVC 104 m 380 m  
4 200 mm RCC 57 m 750 m  
5 350 mm RCC   318 m  
6 400 mm RCC 57 m 60 m  

Details of Manholes

S.No Type of Manhole Zone I Zone II Zone II A Total
1 Rectangular Brick Manhole 165 289 15 469
2 Circular RCC Manhole (Up to 2.5 m) 68 30 -- 98
3 Circular RCC Manhole (Beyond 2.5 m) 46 100 1 147
  TOTAL 279 419 16 714

Pumping Station

The sewage generated from the Zone I is collected at Pumping Station I and is proposed to be pumped to STP. The sewage generated from the Zone II and Zone II A is collected at Pumping Station II and is proposed to be pumped to STP. The capacity of collection well has been determined in such a way that for any combination of inflow and pumping, the cycle of operation for each pump will not be less than 5 minutes and maximum detention time will not exceed 30 minutes. Pumping quantity is 0.5mld for zone I and 1.45 mld for zone II for intermediate and 0.56 & 1.47 mld respectively for ultimate.

Pumping Main

The pumping main carries flow from the proposed pumping station (2 Nos) to the STP.

  • Zone I Pumping Station to STP – 150 mm CI Pipes – 260 m
  • Zone II Pumping Station to STP – 250 mm CI Pipes – 2416 m
  • Zone II A to Zone II – 150 mm CI Pipes – 30 m

Sewage Treatment Plant

It is necessary to provide complete biological treatment of sewage before disposal into a water way. The type of treatment is generally decided based on the effluent standards prescribed by the regulatory agencies, such as Central Pollution Control Board, Tamil Nadu Pollution Control Board.

Considering the available skills and the fact that, the sewage treatment is going to be a new area of activity for the local body to handle, Extended aeration method is proposed for this Scheme.

Details of Sewage Treatment Plant

  • Capacity of STP : 2.33 MLD
  • Technology : EASP Technology
  • Extent allocated : 0.67 Acre
  • Area Required :0.6 Acre
  • Final Disposal : Reuse after let into ULB Pond (Kazhugukulam)
  • Disposal Arrangements: To be conveyed by 350 mm RCC pipes

Cost of the Scheme

The total cost of the scheme works out to Rs. 33.51 Crores for installation and Rs. 24.65 Lakhs for annual maintenance.

Mode of Finance

The Scheme is under implementation with funding from Government of india 50%- Rs11.66 Crores,Government of Tamil Nadu- Rs 4.66 Crores,Urban Local Body-Rs 7.00 Crores and IUDM Share of Rs10.19 Crores.


On completion, the scheme will be maintained by the Contractor for the period of 5 Years and after that the Scheme will be maintained by Town Panchayat.

Present Stage:

The work order for the scheme has been issued on 02.01.2017 and work commenced on 27.01.2017. So far, 53% of work has been completed and expenditure incurred is Rs. 13.55 Cr.(48%) .

This Scheme is targeted for completion by 1/2019.

Salient Details