HAL Group Inc. was retained by HATCH Ltd. on behalf of Metrolinx to carry out a specialized field investigation of a 2700 mm combined sewer system. The work focused on two manholes, supporting condition assessment and rehabilitation planning within a critical underground infrastructure corridor.
TARGETED FIELD INVESTIGATION
The investigation included the extraction of ten (10) concrete cores to evaluate the condition of the sewer structure. Testing locations were carefully selected to capture representative conditions within the host liner installation (HLI) system.
STEEL LINER EXPOSURE & ASSESSMENT
The steel liner was exposed at eight (8) locations to visually assess its condition and identify any signs of corrosion or deterioration. These exposures also enabled accurate measurement of mortar and shotcrete thicknesses, providing key data on liner performance and integrity.
ADVANCED MATERIAL TESTING
Recovered core samples underwent comprehensive laboratory testing, including petrographic examination, pH analysis, sulphate attack assessment, and compressive strength testing. These results provided valuable insight into the durability and chemical resistance of the existing materials.
CONFINED SPACE EXECUTION & COORDINATION
All work was conducted within a confined space environment, with a dedicated rescue team present on-site to ensure safety compliance. Coordination with Toronto Water (DOS) enabled temporary flow diversion from the HLI, allowing safe access for in-situ investigation and testing.
Metrolinx Combined Sewer Investigation: Assessing the Core of Underground Infrastructure
