STEP Regional Odour Control Facilities System

Odour control is a key component of STEP - Strategic Tunnel Enhancement Programme for the Sewer system. A centralized odour extraction approach was initially recommended and validated through detailed modeling. However, ADSSC required greater certainty regarding the volumes and movement of air within the tunnel and link sewers so it directed that physical modeling be conducted to quantify air entrainment values at drop structures and further evaluate centralized versus regional odour extraction system approaches. As an outcome, a regional odour extraction system was implemented at shaft WS-4 and at shaft WS-7, with a two-stage treatment consisting of bio-trickling filters followed by carbon polishing.

Due to deep excavation work, instrumentation monitoring was important for risk assessment. Geotechnical and geodetic instruments were installed in the diaphragm wall and soil to provide settlement, deflection, and deformation data for verifying the initial design of permanent structures and temporary works supporting the excavation.

Encardio Rite’s sister concern, Rite Geosystems LLC in UAE, was entrusted with the complete monitoring works of the project that included 

• Supply, installation, and monitoring of geotechnical instruments that included inclinometer, prism targets, and settlement points
• Optical Surveying
• Daily & weekly reporting with evaluation & Interpretation