Case Studies on Environmental Emissions of Machinery and Material Use due to Bored Pile Construction

Irrespective of the large impact exerted by the building sector on the environment because of intensive resource and energy utilization, much less attention has been paid to understanding the emission contributions due to machinery and resource consumption in pile foundation construction. Four piling sites were selected in Sri Lanka to estimate and compare the contribution on Global Warming Potential (GWP) caused by heavy machinery and material use for in-situ bored pile construction, based on the Intergovernmental Panel on Climate Change (IPCC) methodology. Accordingly, machinery and material related data were collected. In parallel, soil conditions as assessed by SPT-N values were used to characterizes oil, which displayed loose sand to very dense clayey or silty sand in the selected sites. The average Green House Gas (GHG) emission due to machinery used for each project revealed that the GHG emission of pile boring varied from 7.4 to 20.48 kgCO2-e per m3 of pile bored across the project sites, the project in Mannar recording the lowest while the project in Kandy recording the highest. Compared to machinery emissions, materials had a higher emission contribution to the total, varying in the range of 86% to 93% across the project sites. Analysis of GWP attributable to piling machinery revealed that the highest contributions were from boring rigs compared to excavators and cranes. Further, statistical analysis of forcing factors for machinery emissions revealed that operator experience and engine capacity have significant impacts on emissions. This study helped to recognize high-emitting bored piling machinery work and enhance environmental and economic sustainability of bored pile construction.