A case study on addressing sustainability in DBO contract for reconstruction, expansion and operation of Pagla STP under Dhaka sanitation improvement project, Dhaka WASA

Abstract

Dhaka, the capital city of Bangladesh, faces significant challenges in wastewater management, with existing sewerage facilities covering only 20% of its population. Dhaka Water Supply and Sewerage Authority (WASA) has undertaken an initiative to bring the core city area into a planned sanitation system- the reconstruction and expansion of Pagla STP is a part of that plan. This practicum report explores the integration of sustainability principles in the Design-Build-Operate (DBO) Contract by assessing the incorporation of environmental, social, and economic sustainability and providing recommendations for improving contract structuring and long-term sustainability in wastewater infrastructure projects. The study also identifies gaps in Pagla STP's existing DBO contract and proposes strategies to enhance efficiency and sustainability throughout the project lifecycle. The methodology adopted in this study includes a qualitative and analytical approach, with data collected through literature reviews, key informant interviews (KIIs), stakeholder consultations, field observations, and focus group discussions (FGDs). Comparative analysis and SWOT assessments were used to benchmark the sustainability performance of the Pagla STP against similar projects globally. Key findings highlight the sustainable design and operational features of the Pagla STP, such as: • Water Quality Improvement: The project aims to treat 200 million liters per day (MLD) of sewage, significantly reducing pollution in the Buriganga River and improving aquatic ecosystems. • Greenhouse Gases (GHG) Reduction: The project incorporates anaerobic digestion to capture methane and generate biogas, which will be used for power generation, thereby reducing environmental impact. • Energy Efficiency and Renewable Energy Use: The plant will utilize energy-efficient motors, LED lighting, and solar power for 10% of its total lighting load, enhancing energy sustainability. • Sludge Management: Anaerobic digestion will reduce sludge volume by approximately 30%, lowering disposal costs and promoting circular economy principles. • Community Benefits: The installation of modern odor control systems will improve air quality, while the provision of a septage decanting station will extend sanitation services to hard-to-reach areas. • Carbon Footprint Reduction: The project is expected to result in a net emission reduction of -605,466 tCO2-eq, aligning with global climate goals. The study concludes that the DBO contract structure effectively integrates sustainability measures, enhancing environmental protection, social equity, and economic viability. Recommendations include refining contract documents to further incentivize sustainable practices, strengthening stakeholder engagement, and incorporating advanced technologies for enhanced resource recovery. By implementing these measures, the Pagla STP project can serve as a model for future sustainable wastewater infrastructure projects in Bangladesh and beyond.