Maccaferri installs MacBags, Sack Gabions, and Gabion Mattress in order to alleviate costal erosion along the River Hooghly, Kolkata, West Bengal
The Cheviot Group of Companies, (Caledium Jute Mill) is located along the River Hooghly, at Budge Budge, 24 Paraganas, Kolkata, West Bengal. Various phenomena can be observed in the seas and oceans where the river mouth opening is funneled into shallow and narrow river sections. Tidal Bore is one such phenomenon which occurs in the estuary zone. There are very few locations around the globe where this event occurs. The Budge Budge region of Kolkata is one such location in India where the event occurs. The intense turbulence and the hydraulic jump caused as a result of the Tidal Bore, have gradually damaged the compound wall of Caledium Jute Mill.
To mitigate this problem, Cheviot Group of Companies proposed bank protection works and contracted Maccaferri Environmental Solutions Pvt Ltd to install MacBags, Sack Gabions, and Gabion Mattress in the face of high levels of erosion.
The anti-erosion works were being implemented in a 100 m stretch of the Ganga river along the compound wall of jute mill that was identified as a highly affected zone.
Construction during the Tidal Bore is highly challenging and nearly impossible given the significant tidal variations that occur in these regions. The funnel shape increases the tidal range and reduces the tidal duration of the flood tide. Turbulent mixing is generated during the occurrence of Bore Tide. The effects of such mixing are felt along the specified distances. The maximum height of the tidal bore observed was approximately 2 m and the velocity was 7—10 m/s. Tidal Bore occurs once or twice in a month and condition extends for 2-6 days occurring once each day.
In light of these environmental circumstances it is important to carry out the construction plan so that the system continues to sustain itself even during tremendous loading conditions. The design thickness calculation of the scheme aims to support the load imparted by the Tidal bore. This process has to be completed during the construction phase. Thus, the focus was placed particularly on embankment protection systems using Geosystems. The height of the embankment to be protected was approx. 6 m and slope 1V:2H. The thickness of system was analyzed and estimated to be approximately 3 m thick. Geotextile bag (MacBags) filled with sand are commonly adopted as a solution for river hydraulics problems.
These Bags are preferably produced from woven Polyester Geotextile material. Maccaferri’s containment system–Sack Gabions lined with Geotextile material and filled with dry sand were thus installed to prepare the foundation base for the structures.
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