Friday, July 28, 2017

Uttarahalli Lake Report


Summary
Uttarahalli Lake is located in Uttarahalli, Bangalore opposite to Rajathadri Palace Hotel on Dr. Vishnuvardhan Road in the southwestern part of the city and is frequented by many local residents during its open hours. The lake attracts many bird species that wade in the natural wetland in the north. The STP is to be upgraded with a treatment capacity of 1 MLD of sewage. Due to current construction, the STP was not operating on the day of our visit (5 Jul 2017) and the location of the STP treated water discharge will change. The six inlets and monsoon rains ensure that there is water in the southern part of the lake all year. The diversion drain discharges outside of the lake and would combine with any overflow leaving the outlet. Uttarahalli Lake appears to be disconnected from the chain of lakes, but would fall within the Byramangala Lake Series. Note for map below - N: Naala, I: Inlet, POI: Point of Interest. Map labels match up with corresponding legend element. 




























Overview and Observations
Uttarahalli Lake is located in Uttarahalli, Bangalore.
Lake Area
15 acres 16 guntas
STP
Capacity: 1 MLD; Activated Sludge w/ Tertiary Treatment
There are six separate sources of inflow into the lake and one outflow from the lake.

In the mornings and evenings, many local residents use the 0.85 km path around the lake for walking, jogging, or other workouts. There is a gazebo and outdoor gym at the SW corner of the lake and a badminton court along the western side of the lake. The north corner of the lake has a playground for children and benches for adults to supervise. The toilet facility is also in the northern part of the lake just south of the STP. There is a diversion drain around the entire lake except a few patches where it was not clearly visible. 

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Left: Gym equipment and gazebo in background. Right: Badminton court.

There are 3 gated entrances into the lake property. Near the northern entrance across from the playground, there is a cemetery.
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Small cemetery (taken from playground area facing north)

The guard office is next to the southern gate. Additional safety is provided by the fence surrounding the property and the inner fence between the lake and the walking path. The path is paved and lined by many trees and shrubs. According to the guards, fishing contracts are not allowed at Uttarahalli Lake.

The Lake
We identified six distinct inlets where water would enter Uttarahalli Lake.
Inlet
Name
Description
Pictures
1
Treated STP Water
Not currently discharging due to construction. Location unknown and may change (point on map is location prior to earthwork).  

2
Naala 1 Overflow
During a rain event, Naala 1 overflows and directly enters into the northern lake area which is bounded by a bund but currently has no vegetation. Levelling of the lake bed is being undertaken in that region.
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3
Culvert 1
Not currently discharging. It opens into the northern portion of the lake which is bounded by a bund. The source is undetermined.
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4
Culvert 2
A culvert opens into the lake near the badminton court. It is not discharging and the source is undetermined.
5
Naala 2/
Culvert 3
Untreated sewage in Naala 2 (originating outside the lake and runs under the road) enters the property from behind the gazebo and flows into a culvert which discharges directly into the lake near the outlet.
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6
Culvert 4
Two culverts open into the southern edge of the lake. It is suspected that this discharge is stormwater from the nearby road which is collected in a covered drain. They are not currently discharging, but would flow directly into the lake.
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It should also be noted that another culvert (POI 2: Culvert 5), originating from a residential road, was located in the northeast corner of the lake. Culvert 5, however, connects directly to the diversion drain which is believed to divert stormwater/sewage around the lake and discharge elsewhere. Therefore, Culvert 5 is not considered an inlet for lake inflow. There is another open drain (a small, dirt naala - Naala 3) which flows into that same diversion drain. Additionally, stormwater from Dr. Vishnuvardhan Road enters into southern portion of the drain system through small inlets.
Covered diversion drain around the lake. Bottom left: Naala 3 flows into the drain.

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The only outflow from the lake is an overflow system under the bridge in the SW corner of the lake. 

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Overflow outlet from Uttarahalli Lake as seen from north (near STP) facing southwest.

Around the edges of the lake, there was a significant amount of algae on the surface as well as a slight green hue to the entire water body.

Along the walking path, there was what appeared to be an HDPE underground Syntex tank (POI 2: UST) across the walking path to the south of the STP. Also along the path, next to the children’s playground, there was a borewell. Whether or not it is yielding is unknown.

The plant growth around the lake is maintained by contracted individuals who trim the grasses. The Karnataka Home Guards provide security at the gates.

In addition to the BBMP, both United Way of Bengaluru and the Uttarahalli Magakere Walkers’ Association are responsible for the lake’s rejuvenation. The Walkers’ Association is in charge of daily maintenance of the lake.  

The STP
The STP at Uttarahalli is owned by the BBMP. The STP is to be upgraded with a treatment capacity of 1 MLD of sewage. The sewage from Naala 1 flows in a drain in the direction where the STP is located. The STP discharge into the lake is not seen due to construction, but when it functions, the treated STP will certainly be let into the lake. With the significant increase in future STP discharge into the lake, water levels are expected to rise.

The current STP uses activated sludge technology with aeration, secondary, and tertiary treatment processes.

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STP process overview (the picture is taken from the Dorekere STP as the process remains the same)

The Wetlands
Currently, the areas which would normally be engineered wetland are being levelled because there was excess soil built up. Both of these places are bounded by a rock bund but are not planted and have no water while the work is being completed. Additionally, there is a natural wetland in the mid- to northern portion of the lake due to shallow water. This area attracts many birds.

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Contacts
  1. BBMP Uttarahalli Lake Incharge : Usha Rani , 91 98860 46498
  2. STP Incharge : Narayan , 0 81239 75078
  3. UWBe : 080 4090 6345, 080 2525 8363, info@uwbengaluru.org




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