Comparative Life Cycle Cost Analysis of Trenchless and Traditional Sewerage Rehabilitation Methods: A Case Study of Tanga Urban Water Supply and Sanitation Authority, Tanzania

The sewerage infrastructure in Tanga City, managed by the Tanga Urban Water Supply and Sanitation Authority (TANGA UWASA), faces significant challenges due to ageing pipes, coastal corrosion, and urbanisation pressures, leading to frequent failures and environmental risks. This study conducts a Life Cycle Cost Analysis (LCCA) to compare trenchless technologies (TT), specifically Cured in Place Pipe (CIPP), with traditional open-cut methods for rehabilitating a 1 km, 225 mm diameter sewer line over a 50-year lifespan. Utilising primary data from TANGA UWASA, contractor estimates, and stakeholder surveys, the analysis employs Net Present Value (NPV) modelling. Results indicate that CIPP offers 48.2% cost savings (TZS 4.67 billion vs. TZS 9.01 billion) compared to open-cut methods, driven by reduced maintenance costs (TZS 110 million/year vs. TZS 275 million/year), less frequent rehabilitation (every 25 years vs. every 10 years), and lower indirect costs (TZS 600 million vs. TZS 2,100 million). Environmentally, CIPP reduces excavated material by 95% (60 m³ vs. 1,200 m³) and contamination risks by 82%. Socially, it mitigates traffic disruptions by 78% and business losses by 70%, yielding TZS 510 million in benefits. Key barriers include reactive maintenance practices (72% of activities), lack of expertise (70% of contractors are untrained), and financial constraints. Recommendations include a TT pilot on Street No. 10/Makoko Road, capacity-building partnerships, and policy incentives aligned with Tanzania’s National Water Policy (NAWAPO, 2025). This study provides a robust framework for TANGA UWASA to adopt cost-effective, sustainable sewerage rehabilitation, enhancing urban resilience and public health.