Phasing of a Geotechnical Investigation - Pay Now, or Pay More Later. The Hanlan Feedermain Approach to Risk Mitigation

The Region's Hanlan Water Project is a 96-inch diameter feedermain extending 8.7 miles. CH2M HILL and the Region of Peel implemented a thorough two-phase approach to their geotechnical subsurface investigation on the southern 5.6 miles of the project, consisting of approximately 3.7 miles of tunnel at depths varying from 52 to 92 feet, and 1.9 miles of open cut. Phase I of the geotechnical site investigation included a review of existing geotechnical information. A borehole plan was developed and executed to provide information for the entire alignment and to focus in on site-specific issues. A seismic survey was performed to further confirm the competent rock boundary. Phase II of the investigation included review of the Phase I information and the placement of additional boreholes and tests in order to fill gaps in the data. The results will be used to mitigate risk through the Geotechnical Baseline Report and specific risk mitigation articles in the Contract.