I need information
What is the existing policy?
What is the restoration process for lakes?
What are the preventive precautions?
What is Wet Land Treatment?
What does it cost to restore and rejuvenate a Lake?
Although there does not seem to be any clear policy in place, the Government of Karnataka in 1985 constituted an Expert Committee in the year 1985 headed by Shri N. Lakshman Rao, to study the problems and suggest remedies for the preservation and restoration of lakes in the metropolitan area of Bangalore City. The High Court in turn ordered that immediate steps be taken for implementing the G.O. dated 11-02-1988 and also to carry out the recommendation of the expert committee constituted by the Government in the year 1985.
What is the restoration process for lakes?
The lake can be restored at various stages.
The stages are mentioned as under:
• De-weeding
• Interception and diversion of sewerage entering lakes
• De-siltation of lake beds
• Providing an embankment with silt and stone pitching
• Creating islands for birds
• Improving and creating habitat for aquatic life
• Protection of lakes from human and animal interference, by fencing
• Providing sewage treatment plants wherever sewage enters lakes
• Monitoring quality of water in the lakes
• Community participation and public awareness programmes for conservation of lakes
• Research and training for lake maintenance
• Providing recreational activities like boating and jogging paths.
What are the preventive precautions?
When lakes are emptied for rejuvenation, it is anticipated that the bio-diversity that is disturbed, takes approximately twenty years to re-emerge. It is therefore imperative to be proactive in maintaining our lakes.
For sustaining the improved conditions of lakes after the restoration, it must be ensured that the water let into the lakes from storm water drains (SWD) is treated, so that the lake can maintain a balanced ecological system. Generally, SWD's are let into the lakes in order to re-charge the Lake, but this water is highly contaminated as certain illegal sewage lines enter the SWD's. This contaminated storm water must be adequately treated before it is let in to the lakes. STP's treat the sewage water at primary, secondary and tertiary levels. Primarily treated water can be let into wetlands for further purification, before being let into the lake.
The capital cost of an STP with 1MLD capacity is Rs.250 lakh. An additional cost of approximately Rs.22 lakh per annum is required to meet expenses such as electricity charges, labour charges, other man-power charges and material charges (i.e. chemicals and other cleaning equipments).
The wetland treatment is a purification process that the water undergoes before being let into the Lake. A portion of the lake is bounded as wetland, where water from storm water drains or sewage water, which has undergone primary treatment, is let in. In the wetland, plants such as cattails, bulrush, typhus, reeds, bamboo species, lymphia, and water lilies are introduced. These plants remove the nutrients from the water, which encourage algae growth and the resultant infectious breeding of mosquitoes, to make it clean. This clean water is then let into the Lake.
The wetland treatment method is planned for a couple of lakes the city. For a Lake capacity of approximately 0.7 TMC the wetland requirement is about 12 acres. Besides the cost for land, an additional cost of approximately Rs.10, 000 /acre is estimated for maintaining the wetland. This treatment will help the Lake maintain a Biological Oxygen Demand (BOD) of 5 and below, turbidity to less that 1 and the ph value around 7.
What does it cost to restore and rejuvenate a Lake?
The unit cost involved in restoring a lake is as under:
Cost of restoration/hectare
I. De-silting: 10, 50, 000
II. Revetment: 52, 500
Revetment: 52, 500
However, a good benchmark to use for the rejuvenation of a poor quality lake is: Rs.12.5 lakh per hectare. This includes recharge of water, diversion of sewage, de-silting, providing silt traps, fencing, and green frontage.
Revetment: It is a technical term, which means that stones or other material that are used to strengthen a wall or hold back a bank of earth.