1. Performance monitoring of all STPs in Chennai, especially those commissioned under NRCP reflecting the impact of CCRCP.
During 2000-01, the Government of Tamil Nadu, along with the Government of India formulated the Chennai City River Conservation Project (CCRCP) with an objective to: i. Prevent sewage entering into the waterways.
ii. Augment the treatment capacity of the Sewage Treatment Plants at
Nesapakkam, Koyambedu, Kodungaiyur and Perungudi. iii. Keep the city waterways clean on a sustainable basis.
The Ministry of Environment & Forests, Government of India during the year
2000-01 had sanctioned a sum of Rs.491.52 crore for the component “Prevention of untreated sewage flow reaching waterways in Chennai City”, which was carried out through Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) under NRCP. The following are the major components:
S.No. Work Components Amount (Crore) 1 Strengthening & Capacity expansion of sewer system 382.00 2 Construction of STPs 109.52 Total 491.52
CCRCP was commenced and implemented by CMWSSB from the year 2001 in
16 packages. These works were implemented not just in the Cooum River Basin, but also in Adyar River Basin, Captain Cotton Canal Basin, Otteri Nallah Basin, Buckingham Canal Basin and in Mambalam Drain Basin.
The project consisted of laying of interceptors for a length of 59.2 km, improvements to 28 pumping stations, construction of 3 new pumping stations, laying of sewage pumping mains for a length of 28.85 km and gravity conveying mains for a length of 17.3 km through 12 packages. Construction of 4 sewage treatment plants to enhance the sewage treatment capacity by 264 MLD was carried out in Packages 13 to 16. CMWSSB had completed all the 16 packages by 2006. The expansion of sewage treatment capacity by 264 MLD by constructing 4 Sewage Treatment Plants and commissioned under NRCP is detailed below:
S.No. Treatment Plant Old Treatment New Treatment Total Plants Plants constructed Capacity under CCRCP (MLD) 1 Kodungaiyur Zone I 80 - 80 2 Kodungaiyur Zone II 80 110 190 3 Koyambedu 34 60 94 4 Nesapakkam 23 40 63 5 Villivakkam 5 - 5 6 Perungudi - 54 54 Total 222 264 486
The sewage treatment plants are presently being operated and maintained by CMWSSB. The Tamil Nadu Pollution Control Board regularly monitors the performance of all STPs by collecting treated water samples. The report for the period from April 2013 to March 2016 submitted by TNPCB is enclosed.
2. Stage wise reduction in BOD values starting from commissioning of the proposed project and tending to the prescribed norms.
To monitor the water quality before and after restoration, BOD5 was fixed as the baseline parameter and observation was done during DPR preparation in the year 2016. The values obtained during the monitoring period were fixed as base line data for this project.
The expected outcome is that there will be a reduction by 52 % of BOD5 at two monitoring locations within Chennai city (Napier bridge and Cholaimbedu bridge), upon successful implementation and completion of the Eco-Restoration Project in the short term phase
(2020). Further, upon completion of subprojects in the medium term phase (2023), the BOD5 is expected to reduce by 55 % within Chennai city. At the end of year 2032, about 97% reduction of BOD5 is expected and the water quality will be to the standards of Class “B”
Outdoor bathing (organized) as per the criteria of CPCB. The anticipated BOD5 values after completion of the project at the monitoring stations are given below:
3. The project shall take care of all likely developments in the river basin proposed in the next 25-30 years, and meanwhile, there shall be complete sewerage network/UGD ensuring no ingress of untreated/partially treated wastewater to the river.
Originally, Chennai city had an extent of 176 sq.km and was locally administered by
Chennai Municipal Corporation. In the year 2011, Chennai city was expanded to an extent of
426 sq.km by annexing 42 adjacent local bodies which include 9 Municipalities, 8 Town Panchayats and 25 Village Panchayats. Chennai city, with its extended area, has further been expanded by adding adjacent and distant peri urban areas of Thiruvallur and Kanchipuram Districts all of which now constitute the Chennai Metropolitan Area (CMA) with a total extent of 1180 Sq.km.
The core city (176 Sq.km) is entirely covered by sewerage system. Rapid urbanization and increasing population has thrown up several challenges and the city is expanding vertically. Individual houses are being converted into multi-storied buildings with several dwelling units. Though erstwhile Chennai was fully covered with a sewerage system, a portion of untreated sewage found its way into the waterways due to capacity constraints of sewers. The Chennai Metropolitan Water Supply and Sewerage Board has taken up works to strengthen and augment the infrastructure facilities in the sewerage system within core Chennai city. These works include enlargement of sewage pumping main, construction of road side pumping stations, improvement to existing pumping stations (provision of diesel generator sets, pumping sets), enlargement of existing sewer mains, and laying of new sewers at an estimated cost of Rs. 313 crores in two phases. Phase I is nearing completion while Phase II is underway. In order to meet the wastewater treatment capacity for the growing population within core city, added areas and adjacent ULB/RLBs, the augmentation of existing STPs and new projects were taken up by CMWSSB and Commissionerate of Municipal Administration. The details of existing/under construction STPs are provided in the table below:
S.No Name of STP Capacity Year of Construction Technology (MLD)
Kodungaiyur Plant I 80 1989 ASP 1 Kodungaiyur Plant II 80 1991 ASP Kodungaiyur Plant III 110 2006 ASP
Koyambedu Plant I 34 1978 ASP 2 Koyambedu Plant II 60 2005 ASP Koyambedu Plant III 120 2015 ASP
Nesampakkam Plant I 23 1974 ASP 3 Nesampakkam Plant II 40 2006 ASP Nesampakkam Plant III 54 2013 ASP
Perungudi Plant 1 54 2006 ASP 4 Perungudi Plant 1I 60 2012 ASP Plant III (Alandur) 12 2003 Extended Aeration 5 Thiruvottiyur 31 Under Construction ASP 6 Sholiganallur 18 Under Construction SBR 7 Avadi 36+4 Under Construction SBR 8 Thirumazhisai 3 Under Construction Extended Aeration 9 Tambaram 30 Under Construction SBR
The adjacent local bodies (since merged into the Chennai Corporation area) surrounding the city limits gradually became urbanized by migration and settlement of people from other parts of the State. These added areas have not been covered under UGSS. To prevent ingress of untreated wastewater into Cooum River, the State Government has also taken up works in providing sewerage and infrastructure facilities in the added areas of Chennai Corporation and the adjacent ULB/RLB within Chennai Metropolitan Area keeping in mind of the growing population especially in the Cooum river basin. The detail of ongoing projects and proposals for sewerage systems in the Cooum river basin is provided in table below: