Project Description

This project required a site investigation, foundation design recommendations, and maximum allowable soil bearing pressures for use in the design and construction of a proposed communication tower at the summer residence of the Prime Minister of Canada.

The proposed tower was an open steel frame lattice tower structure subject to gravity loads, ice buildup, wind loading, and overturning moments. Its dimensions were approximately 2 m by 2 m at a height of 25 m, located 145 m from the south shoreline of Harrington Lake in Gatineau Park, Quebec. This site sloped towards the lake, in a north direction, from an approximate Elev. 184.2 to 171.5 m. It was predominantly landscaped grass, with occasional gardens and a medium to large tree cover. A single large two-story summer residence was located approximately 80 m to the northwest of the borehole location, with several security and service buildings located in the general vicinity.

All boreholes were advanced using a track mounted CME 55, a rotary drilling rig equipped with hollow stem augers, and a standard 50 mm split spoon sampler. Soil samples were collected at standard intervals in each borehole and sent to our CSA certified laboratory for further soil classification and testing. The long term groundwater level is estimated to be similar to the nearby lake level, at approximately 12 to 13 m depth.

Surveys indicate the surficial geology for the area is characterised by fluvioglacial deposits consisting of stratified sand and gravel.  The fluvioglacial deposit is believed to overlay probable Canadian Shield granite, as highway cuts in limestone bedrock were observed to the southeast. Geotechnical parameters were reported for foundations, excavations, sliding, earth pressure, seismicity, aggregate backfill, subdrainage, and more.