Monday, September 11, 2017

Puttenahalli JP Nagar Lake Report

Summary
Puttenahalli Lake is on 13 acres, 25 guntas and is located in the south of Bangalore between Brigade Millenium and L&T South City near Millennium Avenue. It is frequented by many local residents who enjoy the provided 1.1 km walking path, horizontal and parallel bars for exercise, gazebo, and other amenities. There are three entry points into the lake premises, one at the northwest and two at the southeast corner. The entire eastern side of the lake is bordered by slum dwellings and is open to nearby roads. There is no STP within the lake premises. However, there is a large area of the lake which is occupied by constructed wetlands, some attached to the lake bed/bund around the lake and some floating. In total, there are 7 inlet points and 1 outlet from the lake. Of those, two are STP treated water from L&T South City apartment complex and five are storm water inlets that flow from neighbouring areas into the lake through culverts. Around the periphery of the lake, there are about 200 trees planted which teems with fish and other fauna.



Overview and Observations
Puttenahalli Lake is located in JP Nagar, 7th Phase, Nataraja Layout Bangalore.
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Lake Area
13 acres, 25 guntas
STP
No STP exists. However, Constructed Wetlands exist in multiple locations of the lake
  • A lot of work has been done in constructing wetlands inside the lake by many players which includes: government bodies like BBMP, educational institutions like BMS College of Engineering, Puttenahalli Neighbourhood Lake Improvement Trust, etc.
  • There are 7 inlet points and 1 outlet from the lake.
  • In the mornings and evenings, many local residents use the 1.1 km path around the lake for walking, jogging, or other workouts.
  • We did not observe any buildup of algae on the surface.

The Lake
Seven inlets where water would enter Puttenahalli Lake were identified and are summarized below. All of the inlets except 6 & 7 discharge into silt traps prior to entering the lake or wetlands. In addition, the two STP treated water inlets are filtered through a small grate to capture large debris before it enters the lake (photos below - Inlets 1 & 2).

Inlet
Name
Description
Photos
1 & 2
STP Treated Water
L&T South City apartment discharges approximately 8 lakh liters of its treated STP water into the lake each day at the southeast corner of the lake through two double-culvert structures.
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3-7
Stormwater Overflow
Stormwater from across the lake at different points as shown in the map enter the lake through culverts.
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The outlet from the lake is an overflow system under a bridge in the NE corner of the lake.
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Overflow outlet from Puttenahalli Lake

The STP
There is no STP at Puttenahalli Lake. However, treated STP water from L&T South City is discharged into the lake through two inlets next to each other. Many locals mentioned to us that they observed fish kills when the treated water flow increased. But, it needs to be verified if fish kills occur when the treated water inflow increases or when the rainwater inflow increases. We also observed that there is no smell issue or complaints near the treated water discharge point.

The Wetlands
There are multiple wetlands in Puttenahalli Lake, including constructed wetlands which are floating and/or attached.

Near the entrance in the northwest and the small rest area, there were several floating wetlands.

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Floating wetlands were found throughout the lake

In the southeast corner of the lake, the treated STP water from South City passes through wetlands which consist of floating and attached plants.
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Constructed wetlands (foreground), floating and attached, to further treat STP water from South City

There is also a wetland prior to the outlet which further filters water before it leaves the lake.
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The lake water flows through the wetland and discharges through the outlet which is to the right of the picture above.

Contact Info
Puttenahalli Neighbourhood Lake Improved Trust (PNLIT) : trustees@puttenahallilake.in, puttenahalli.lake@gmail.com, pnlitonline@gmail.com, +91 7259722996, +91 80-41206057

References


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