Case Study -1 Pollution Abatement In Rivers
Feasibility Study for pollution abatement in the selected river stretches of Vaigai, Cauvery and Bhavani Rivers
Water is a prime source for all the living creatures in this world for its existence. It exists in the form of Surface Water as well as Groundwater. The forms of surface water are lakes, ponds, rivers etc., which can be quantified easily; it is prone to pollution and vulnerable also. However groundwater cannot be quantified easily as it requires some external instruments and sophisticated computer applications, it is also prone to pollution but the rate and extent of pollution rate is low when compare with the surface water.
In most cases surface water gets polluted by human intervention in the way of disposing human waste, sewage into the lakes/ponds and rivers and dumping of solid waste in water bodies. On the other hand, the growth of industries had also played a major role in polluting water bodies by the way of disposing the industrial effluents into the water body. One such common problem in metro cities of India is pollution of rivers by disposing of domestic sewage and industrial effluents into it.
Lack of proper infrastructure such as Under Ground Drainage (UGD), Sewage Treatment Plant (STP), and lack in proper treatment processes leads to the problem of environmental degradation as well as pollution of water bodies. Hence it is essentially needed to prevent the surface water bodies especially Rivers and its ecology.
TWIC has carried out feasibility study in the Vaigai River Stretch in Madurai City, Bhavani River Stretch in Mettupalayam, Cauvery River in Pallipalayam, Kumarapalayam and Srirangam in Trichy with consideration of various options for pollution abatement of rivers:
- To assess the existing sewage pumping station and Sewer network for adequacy and O&M issues, revamp it for proper pumping to the existing STPs without bye-passing, overflow, leakages etc.,
- To collect the generated raw sewage through a collection well and pump it to the existing STP based on its proximity.
- To plug the sewage outfalls from the sewered area and pump into the existing pumping station.
- Planning of Under Ground Sewerage System for unsewered / uncovered areas / added areas in the municipalities and corporation limits.
- Decentralized Waste Water Treatment Plant.
- Planning of constructed wetlands to treat the raw sewage naturally and eco-friendly.
- Creating a buffer zone along the river bank with natural vegetation to treat the raw sewage naturally.
Diagnostic Study and Feasibility Reports have been prepared and submitted with Block cost estimation and Means of finance
Case Study - 2 RESTORATION, REJUVENATION OF WATER BODIES
Consultancy Services for preparation of DPR for restoration, rejuvenation of 60 Water bodies in Greater Chennai Corporation Area
Greater Chennai Corporation (GCC) area is abounding with water bodies, tanks, rivers and waterways. Due to urbanisation and changes in land use within GCC, the water bodies and the waterways have lost its services and degraded due to public apathy by using the water bodies as dumping ground and disposal of wastewater. To revive the water bodies and to rejuvenate its ecosystem services, the Government of Tamil Nadu has announced under the Sustainable Water Security Mission for restoration, Rejuvenation of Rivers, Water Bodies, Waterways etc.,
Under this context, GCC has appointed TWIC for providing consultant services for preparation of Detailed Project Report (DPR) for restoration, rejuvenation of 60 Water bodies in GCC jurisdiction especially in Central and South Zone of GCC area.
The various interventions that have been studied for the restoration of water body:
DPR has been prepared based an integrated approach for Restoration of water bodies
Considering the complex problem of catchment area and ecosystem of each water body the following will be identified in the study of each water body in an integrated manner.
Hydrological Interventions
- Hydraulic Improvement of feeders (Cleaning, deepening, widening and embankment stabilization)
- Periodical maintenance
Environmental cum Ecological Interventions
- Creating awareness on solid waste dumping in the water body.
- Stakeholder involvement in the maintenance of water body.
- Greening the water body periphery.
Engineering Interventions
- Renovating the existing inlet and outlet structures for their contribution in storing the water.
- Adequate Fencing of water body to stop unauthorized entry.
- Preventing unauthorized encroachments.
Field survey and investigation carried out for preparation of DPR:
Collection of primary and secondary data of Ownership of pond, Area of the Pond, Computation of Change in Lake from FMB area, Inlet and Outlet Channels, Connectivity of Pond, Drainage Networks
Topography and Bathymetry survey, Geo-Technical Investigation, Hydrology and Hydrogeology Study for calculating Micro Watershed Delineation using Carto-DEM, Flow accumulation point of Lake Micro Watershed, Lake Micro Watershed Flow Vectors, Estimation of Water spread area and capacity of water body
Collection of Rainfall including Daily Rainfall data collected for the years 1999 (Drought year) and for the year 2015 (Flood year), Estimation of Watershed based surface runoff and Water body Daily Storage, calculating Combined catchment estimation (Micro watershed + Water spread Catchment)
Geology: Geophysical Investigation, Groundwater Scenario, Slug Test-to determine the Transmissivity and Permeability of the formation in the water body
Carried out Environmental and Social Assessment (EA and SA), Water Quality analysis, Studied on Land use pattern surrounding the lake.
The following landscape design concept and water quality improvement works has been proposed for restoration of water bodies:
- Sustainable Interactive Landscape Concept.
- Bund with stepped wetland treatment.
- Tank bund walk areas are provided with hedge plants and trees.
- Gabion seat wall at regular interval of 4 to 5 m with gabion column lighting.
- Storm water inlet zone is provided with 3 levels of wetland treatment.
- Constructed wetland, Floating Aerators and biomatrix system has been proposed for water quality improvement and circulation.
- Fishing decks & paddle boat docks are provided for Interactive zone.
- Treatment pond at the edges to act as polishing ponds to treat the water from the catchment area
Other General improvements works are suggested for restoration, rejuvenation of Water bodies:
- De-silting Provision made to improve the storing capacity of the pond.
- Providing a filter arrangement in the SWD inlet.
- Providing Constructed wetland system and floating wetland system to improve water quality
- Construction of compound by chain-link fencing.
- Bund formation and revetment provided for protection.
- Surplus arrangement provided to dispose of the flood to nearby SWD.
- Providing LED lights.
- Capacity building and Training programme to Stakeholders
The followings are the benefits are being achieved through pond/tank restoration and rejuvenation.
- Comprehensive improvement of selected tank systems including restoration.
- Improvement of catchment areas of the tanks.
- Groundwater recharge.
- Increase in storage by restoring the capacity of water body.
- Increase in recharge of groundwater in downstream areas of water bodies.
- Environmental benefits through improved water use efficiency, irrigation benefits through restoration of water bodies, supplemental of the groundwater use and promotion of conjunctive use of surface and groundwater.
- Development of Tourism, cultural activities.
- Increased availability of drinking water.
