Root Cause Analysis of Schedule Variance in the Implementation of a Seawater Desalination Project in the Western African Region

Abstract

This study investigates the root causes of schedule variance in a seawater desalination EPC project executed by VA Tech Wabag Limited in Western Africa. Using the Critical Path Method, PERT float analysis, Earned Value Management, Fishbone Diagram, and Five Whys technique, the study traces a shift from a peak positive Schedule Variance of US$ 8.47 million to a negative variance of US$ 3.58 million by July 2024. The critical path spans 906 days through ten zero-float activities. Engineering delays (28%) and procurement delays (25%) together account for over half the total schedule variance. Root causes include immature specifications at procurement initiation, absence of engineering-procurement interface gates, inadequate logistical risk planning, and weak client document approval mechanisms. The study recommends formal interface gate checks, contractual review timelines and monthly EVM dashboards with automatic SPI alerts as preventive measures for future EPC projects.