A Barrier Wall for the New Dam at the Godavari River Installation with Monsoon Break-Paper

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The Polavaram Irrigation Project in Andhra Pradesh, India, is a multipurpose dam intended to support irrigation, hydropower, industrial water supply, and drinking water. Bauer India and L&T Geo constructed a 1,450 m plastic-concrete cut-off wall beneath the dam to limit seepage. The wall varied in depth with the geology, reaching nearly 94 m beneath the Godavari River, and required about 68,000 m² of trench excavation.<br /><br />Construction faced loose sands, clay, boulders, and strong bedrock. Crews used diaphragm-wall methods, including hydraulic trench cutters and grabs, excavating under bentonite slurry and keying the wall into sound rock. The plastic concrete was designed to remain durable while flexible enough to accommodate dam movements and seismic loading. Quality management emphasized verified construction procedures and continuous controls for trench stability, wall continuity, rock embedment, slurry properties, joints, and concrete performance.<br /><br />The river’s monsoon floods presented the principal scheduling and protection challenge. Water levels can rise by around 12 m, while the river expands substantially and flows rapidly. The project was therefore planned in two construction phases, with work stopping during the 2017 monsoon. Before the flood, sections of wall protruding above the original riverbed were trimmed to about 1.5 m below bed level and covered with compacted river sand, allowing floodwater to pass over without scouring the wall. A repair plan was also prepared in case damage occurred.<br /><br />After the floodwaters receded, surveys confirmed that the wall remained intact; the contingency repairs were not needed. Work resumed as planned, and the cut-off wall was completed in June 2018, before the next monsoon.

Keywords

Polavaram Irrigation Project

Andhra Pradesh

cut-off wall

plastic concrete

seepage control

Godavari River

diaphragm wall

monsoon floods

bentonite slurry

hydropower