The main trunk sewer (MTS) is a major element of the Doha South sewage infrastructure project. The MTS is a gravity-based sewerage system that conveys sewage to the Doha South Sewage Treatment Plant (STW). It is designed conservatively to assure that it is self-cleansing during low flows without accumulation of solids, which could otherwise become a maintenance issue. MTS is also sized to meet projected flows for its 100-year design life. MTS has no pumps, valves or any other mechanical or electrical components within the sewer or associated structures. MTS was constructed using tunnel boring machines which required a limited number of shafts, ultimately limiting adverse impacts to the environment.

The purpose of the new sewer is to accommodate the projected population growth for an additional million people. The project is strategic in nature and was developed to change the entire approach to foul sewer drainage in the Doha South catchment from a pumped sewer network to a gravity sewer network. The aim is to address, amongst other things, serious environmental and health issues resulting from undersized and aged sewerage infrastructure.

By addressing and resolving serious environmental and health issues resulting from undersized and aged sewerage infrastructure, the Doha South sewage infrastructure project both supports and contributes to achieving the Qatari National Vision (QNV) 2030. The QNV 2030 aims to transform Qatar into an advanced country capable of sustaining its own development and providing a high standard of living for its people.

CEEQUAL influenced the practice of reducing carbon emissions during construction. The Carbon footprint management plan which included various resource efficiency strategies integrated requirements from the CEEQUAL assessment (specifically in section 8 and 9). Had it not been for CEEQUAL material, water, fuel, and waste tracking would not so integral to the reporting process. Without CEEQUAL, there would also be less urgency to optimise resources and reduce waste.

The use of CEEQUAL increased the focus of the project team to be resourceful and efficient in the delivery of the project. In terms of the design, the project team reduced material purchased by optimising the concrete lining of the shafts in relations to the geotechnical conditions.