Total Water Management at SwaSwara, Gokarna
The Project:
Primarily catering to the discerning international traveler who seeks to discover his ‘inner vibrations’, Swa Swara, situated on Om Beach, 6km away from Gokarna, Karnataka accommodates 24 Luxurious Courtyard Villas, Ayurvedic Spa, Restaurant, Library Bar, Music Room, Craft Centre, Swimming Pool, Art Gallery, Exhibition Hall, Yoga Space and related accommodation facilities for staff of 60.
The resort has been functional from March 2006.
The Site:
The resort is located on a land of extent approx. 26 acres. Entering from the north, the land slopes down to the beach on the southern side. The upper stretch is relatively gently sloping with scrub vegetation. The middle stretch has a patch of dense vegetation and the lower stretch has a strip of paddy fields and coconut groves which open out into the pristine Om beach.
The soil profile of the site is mainly lateritic, which is reddish brown in colour, having lateritic clay soil texture. The top layers are soft laterite with small boulders; but below depths of 3.0m, hard laterite rock formations prevail.
Concept:
From the initial planning stage, it was obvious that one of the main constraints in the site was lack of availability of potable water.
As the site falls under Costal Regulation Zone I, according to the CRZ norms, 200m from the beach is to be a No Development Zone. Pumping of ground water is prohibited in this zone. There were 3-4 existing shallow wells in the region but unable to yield the water to required quantity and Gokarna does not have any centralized water supply network.
The only other source is water supplied by private tanker lorries; but this, besides being extremely expensive, is also untreated water with uncertain quality.
After considering the various options, M/s ‘Inspiration’ recommended that the best option would be to integrate the concept of total on-site water management for the project at the design stage itself, which would focus on
1. A reservoir with an impermeable lining to collect and store the bountiful rainwater for the dry months.
2. Gokarna does not have a centralized sewerage system and hence the need for a properly designed on the site treatment of sewage and waste water to prevent contamination of ground water in the few surface wells on the site.
3. Recycling of treated wastewater for non potable end uses such as flushing, gardening etc to conserve use of the harvested rain water.
Design of the Rain water harvesting system
Gokarna has an average annual rainfall of 3500 millimetres. The reservoir was needed to be planned for a capacity to address 180 totally dry days. The average annual evaporation loss in Gokarna is 1400 millimetres. Being a resort, the aesthetic appeal of the water body was of utmost priority; so there was a need to maintain a minimum level of water in the lake throughout the year.
Mr. V.N. Gore of Geoscience Services, Mumbai was the structural consultant for the lake. Based on the soil investigation reports and detailed site studies, Mr. Gore recommended that the critical criteria for the lining would be control of hydrostatic pressure in the lateritic soil from the vast catchment, impermeability of the membrane and last but not the least, the aesthetic appeal.
The detailed design encompassed the following:
a. Depth of excavation of lake bed to be limited to the level of hitting hard laterite to optimize on costs.
b. Excavation to be done in a slope of 1 in 1.5 to naturally protect the sides of the reservoir.
c. Network of underdrainage below the lining of the lake to release hydrostatic pressure formation below the impermeable liner membrane and uplift.
d. Lining of lake with 2 layers of LDPE fabric liners – the main liner being 300 micron and top layer with 150 micron LDPE.
e. The floor of the lake was to be protected by a layer of 100mm of sand.
f. The sides were to be protected by pitching with random laterite masonry in a lean mortar.
g. Toe walls at the base of the lake would protect the pitching in position.
h. An overflow weir to divert the overflow from the lake in a controlled manner to the lower side of the`lake.
i. Collection of water from the underdrainage network.
j. A network of subsurface filter drains of various sections to drain the catchment within the site and bring filtered water to the lake.
k. A network of trench drains and filter tank to catch the water from the external catchment, filter it and let it into the lake as additional source.
l. Protective embankments on the sides of the lake to prevent unfiltered run offs into the lake.
The lake ecosystem:
The lake has been developed as close to a natural ecosystem as is possible. There is very restricted activity in the lake. Controlled aquaculture with grass carp takes care of the algae control; to ensure that the fish feed on the algae, feeding of fishes by guests / staff is to be totally discouraged.
Purification of water from the lake:
The purification system for the harvested rain water consists of a simple pressure sand filtration, activated carbon filtration and chlorination for disinfection.
Treatment and disposal of sewage:
In order to optimise the usage of water, the black and grey water (sewage and sullage water from kitchens and bathrooms) is treated and reused for gardening and other non-potable end uses.
The system adopted is known as the DEWATS approach (Decentralised Waste water Treatment System). The black water and grey water from the cottages and various blocks are collected in settler tanks. The primary treatment takes place in these settlers.
Average reduction of BOD in the settler is expected to be between 20 and 25 %.
From these settlers, the effluent is taken to the Anaerobic Baffled Reactor for secondary stage of treatment. In secondary treatment, biological and natural chemical processes are used to digest and remove most of the organic matter.
Several up flow chambers are constructed in series to help digest difficult degradable substances. The sewage flow is directed from top to bottom and up again. During the process the fresh influent is mixed and inoculated for digestion with the active blanket deposit of suspended particles and microorganisms occurring naturally at the bottom (activated sludge) of each chamber in such conditions. The BOD reduction rate of the baffled reactor is about 75 –85%.
The Horizontal Planted Garvel Filter (also called Root Zone System) forms the tertiary treatment. The planted gravel filter acts through the combined working of the filter material, the plants and the roots in the device.
After the planted filter, the treated water with BOD less than 30 mg/l is ready for collection for recycling for gardening. The treated water is collected in the Polishing Pond where it becomes “living water again” by undergoing further biological treatment, through natural UV exposure and flowing through an open water body, with all the necessary natural elements such as fish, frogs, dragonflies and different aquatic plants.
Performance of the system:
The significant achievements in this Project could said to be:
1. It is probably among the best examples for total on site water management as one of its strong concepts from the design stage. This had definite advantages that we could treat the system to blend with the landscape, make the most of the levels in the site.
2. It has helped prove that with the right balance of sensitivity and technology, very high end tourism can be successfully promoted even in very fragile eco systems.
PROJECT DATA
Scope: Design + Build
Location: Om Beach, Gokarna, Karnataka
Timeline: 2005-2007
Size: 68000 sq.ft
Client: CGH Earth Experience Hotels
Collaborators: Vilas Gore; M Thomas (MEP Consultant); Stuba Engineering Consultancy Pvt Ltd
