This project involved the construction of a new two story institutional school, located in at 19 Leeder Lane, in Petawawa, Ontario. The geotechnical report concluded that the building needed to be supported on structurally reinforced spread and/or strip footings for column loads. As an alternative to steel reinforced spread and/or continuous strip footings for columns, Menard Canada proposed an engineering solution utilizing Dynamic Compaction (DC) to densify the upper 6 meters of soil. Soil improvement was necessary to compact loose sand, with the compaction limits extending past the building footprint by 5.5m. Soil improvement provided increased support for the shallow foundations to minimize the potential for total and differential settlements. The objectives of the treatment were to compact the soil in order to obtain a minimum bearing capacity of 200 kPa at SLS, with a minimum safety factor of 3 and to limit total and differential settlement to 25 and 19 mm respectively.
Based on Menard Canada’s design, a 12 ton high energy steel tamper was dropped from a height of 20 meters onto the building foot print and the compaction area extended 5.5 meters past the building envelope on all sides. The first and second phases of compaction were designed to densify the soil to a depth of 8m and the final “ironing” phase was designed to compact the upper meter of fill placed after the compaction craters had been filled in. The DC program was completed on schedule, with all tests achieving better than intended results. Menard Canada successfully delivered a cost-effective solution of soil improvement providing a reliable method, appropriate for the project and site conditions.