Strengthening the bund in Ukkadam Periyakulam Tank Bund, Coimbatore city, India.
TECHSPAN® STR SPAN
TechRevetment® Erosion Protection
Coimbatore City Municipal Corporation
KCP Engineers Pvt. Ltd.
DESIGNER + CONSULTANT
- Terre Armée (Reinforced Earth India Pvt. Ltd.)
- Pinnacle Land Surveyors
The project is located in Coimbatore city in the state of Tamil Nadu. Coimbatore City Municipal Corporation (CCMC) had planned to utilize a tank bund to allow 2-wheel traffic over it to decongest a busy road.
As a pilot project, CCMC had taken up strengthening the 1.4 km long Ukkadam Periyakulam Tank Bund by laying 200mm thick cement concrete blocks at a cost of Rs. 49.5 million.
Strengthening the bund using cement concrete blocks was a tedious and laborious process. Considering the water level and length of stretch to be strengthened, the client was keen to adopt a quick and engineered solution to complete the project within a targeted time frame.
Also, laying CC block required dry bank surface. Considering the fact that Ukkadam Periyakulam lake is a major source of water supply to Coimbatore city, dewatering the tank was not a practical solution and constructing a coffer dam meant incurring additional cost.
The client required a solution which could be implemented under water and contacted Terre Armée in India.
Terre Armée in India proposed to use their TechRevetment® system.
Timely completion and under water installation were the two major challenges.
Since TechRevetment® was a new technique for such application, a major challenge was to convince all stakeholders about the efficiency of the system. Their confidence was won by executing a 56m pilot patch.
Initially, a site survey was carried out in detail. Then, design and site specific construction drawings of TechRevetment® mattress system were prepared.
TechRevetment® solution consists of one layer of non-woven geotextile, then laying of Filter Point fabric form concrete mattress and fine aggregate concrete pumped into the fabric form. The TechRevetment® was installed over the embankment of the bund at not more than 1:1 slope.
After studying the geotechnical and hydrological data of the location, Terre Armée in India decided to use Filter Point (FP) 400 mattress for the application. FP 400 is a 100mm thick (nominal) woven double layer synthetic fabric made of polyester with nominal mass per unit area of 500 gms/sq m and shear resistance of minimum of 100 kg/sq m. The mattress also has filter points at specified intervals to release water pressure. After concreting, this mattress acts as a single unit / mass providing better stability to the embankment.
The project took off in the presence of senior government officials.
Terre Armée in India initially completed a 56m pilot stretch in 36 hours. Later, a 1.2 km stretch was executed in 15 days’ time.
The installation took place under guidelines of experienced engineers of Terre Armée in India.
For underwater installation, divers were used to hold back the fabric form mattress.