Innovative Method of Pipeline Protection by Sheet Piling in River Banks Susceptible to Erosion

Unprecedented flooding in Narmada River in August 2013 caused massive bank erosion at the pipeline crossing location leading to snapping of three pipelines and exposing few others except Reliance Gas Transportation Infrastructure Limited (RGTIL’s) EWPL. All these pipelines were laid by conventional trenchless HDD method wherein the landfall point was located at a relatively safe distance from the bank line. The current velocity at the crossing location being higher during floods coupled with weak bank strata, suitable and tangible measures were required to be taken to protect the pipeline from the shore line to the land fall point in the event of reoccurrence of such an incident. The depth profile of EWPL pipeline from the shore line to the landfall point varied from −18 metre to −3.5 metre from the existing ground level which prompted RGTIL to neglect conventional methods like Pipe anchoring and Installation of rock filled gabions involving massive excavations which could have further destabilized the already fragile bank. In view of the prevailing soil conditions and construction difficulties associated with it, RGTIL adopted an innovative method of Installation of Sheet piles on the upstream and downstream of the pipeline to retain the soil around the pipeline and thereby preventing its exposure. Sheet piles are generally used as temporary structures to retain soil for facilitating deep excavations, as retaining system for large waterfront structures etc. These were perhaps never used in India earlier for any pipeline protection works.