A Case Study—Tilting of Sump Well
摘要
Several lift irrigation projects are being executed in various parts of Odisha State. Water & Effluent Treatment Independent Company (WET-IC) of L&T-Construction has been awarded most of the lift irrigation projects. One of those proposed intake pump houses along with its auxiliary structures is located at Rahapada, near Jajpura district. This article presents a case study of tilting the sump well for the intake structure in the Kharsua River in Rahapada. This is meant for collecting the water and pumping it to the nearest delivery chambers. The pump house is proposed on the sump well. Considering the subsoil conditions, diameter, and depth of the sump, a well-sinking method of construction is adopted. During execution, the well was tilted after sinking 10 m below ground level. The sinking by dredging the soil and dumping the dredged soil on one side of the well continued without noticing the tilt. The tilt was noticed only after the final sinking. At this stage, the observed tilt was 1 in 24 m, which was beyond the allowable limits as per IRC standards. This article discusses the causes of the tilting of the well based on physical observations and analysis. The article also covers the proposed rectification works and their implications on the tilting. Problems during the well-sinking method of construction for intake structures, precautionary measures during well sinking, and the influence of the adjacent structures on the sinking of wells are highlighted.