5th International Conference on Geotechnical and Geophysical Site Characterisation 5 – 9 SEPT 2016
Session Report Environmental Testing by Dr Ian Swa...
5th International Conference on Geotechnical and Geophysical Site Characterisation 5 – 9 SEPT 2016
Session Report Environmental Testing by Dr Ian Swane CPEng, EPA Contaminated Site Auditor
www.jacobs.com | worldwide
Environmental testing most dynamic area in site characterisation Didn’t exist 30 years ago Geo-environmental engineering spawned many new disciplines (eg: Contaminated site clean-up, reuse derelict land, pollution risks posed by engineering structures
Many problems remained poorly understood & role of environmental testing still evolving)
Mount Annan Dam Failure (late 1980’s)
Mount Annan Dam Failure (late 1980’s)
Dynamic compaction at Nan Tien Institute, Unanderra (2013)
Dynamic compaction at Nan Tien Institute, Unanderra (2013)
Ground improvement in highly sensitive clays Geophysical techniques to assess infiltration capacity Geophysical techniques to determine soil density (2) Building on waste disposal area Petroleum H/C impacts on mechanical properties Pollution risks posed by preloading Geophysical techniques to assess a landfill cover Testing for ground heat sinks
Paper (1) - Ground improvement in highly sensitive clays Monitoring the plume of potassium chloride from wells used as ground improvement in highly sensitive clays (Helle et al) Field study - injection of KCl into quick clays Various enviro testing methods including RCPTU (resistivity) Findings: - Cur 25mm limit - Most settlement due to viscous component - Most loaded structure require pile foundations Other issues: - Impacts to GW quality - Soil vapour generation
Paper (6) – Petroleum H/C impacts on mechanical properties Influence of periodic hydrocarbon contaminated bentonite on strength and settlement characteristics of stone columns (Shah & Chokhawala) Experimental study into impacts H/C contamination on soil mechanical properties Vertical loading of 50mm diameter stone columns in 250600mm diameter soft clay tank 650mm high (3 columns/tank)
Paper (6) – Petroleum H/C impacts on mechanical properties Findings: - Reduction in load carrying capacity due to internal slippage - 20% reduction for 6% H/C clay - Vertical permeability in stone column reduced with increase HC contamination - Effectiveness of stone columns in reinforcing clay soil mass reduced with H/C contamination. Shear strength in clay mass improved by 33% with stone column, reducing to 26% for 6% HC clay
Petroleum H/C impacts on mechanical properties
Paper (7) – Pollution risks posed by preloading The effects of preload surcharge on arsenic and aluminium mobilization in pyritic sediment (Karikari-Yeboah & AddaiMensah) Studied pollution risks to groundwater from preloading pyritic sediment at Murwillumbah, northern NSW Findings: - Mobilisation of As & Al from pyritic sediment - As (V) 5-21 µg/L in oxic zone porewater > 13 µg/L aquatic marine water criteria - Al 20-25 mg/L in porewater >> 0.055 mg/L aquatic marine water criteria
Paper (8) – Geophysical techniques to assess landfill cover A preliminary study on evaluating the performance of aged landfill covers using DC and CC resistivity methods (Wu et al) Aged landfill site in Hong Kong – TKO - one of 13 closed sites Cover hydraulic properties assessed using electrical resistivity tomography methods for different weather conditions Direct current (DC) and capacitively coupled (CC) methods
Paper (8) – Geophysical techniques to assess landfill cover Findings: - DC resistivity method capable of identifying geomembrane location, deformation and condition - CC resistivity method capable of surveying ground resistivity changes below geomembrane layer
Paper (9) – Testing for ground heat sinks Observed influence of ambient temperature variations on the analysis of ground thermal response tests (Colls S) Thermal response test (TRT) used for in-situ assessment of ground thermal characteristics Ground heat exchangers (GHEs) for heating/cooling buildings Design requires accurate in-situ thermal properties of ground Full-scale field experiments
Paper (9) – Testing for ground heat sinks Findings: - Ambient air temperatures impact measurements of ground temperatures, thermal conductivity & GHE thermal resistance - Thermal conductivity & GHE thermal resistance could be impacted > 20% - TRT assessment need to account for this impacts
Ground heat sink at Lend Lease The Bond, Sydney
Ground heat sink at Lend Lease The Bond, Sydney
Draft AS1726-2016 Geotechnical site investigations
Definition of “contamination” provided (Section 4.11)
“… the possibility of the presence (of) contamination should be considered during the planning and conduct of geotechnical investigation” (Section 4.11)
“Initial assessment of site conditions… potential for encountering contamination” (Section 5.2.5)
“Planning of geotechnical investigations should include but not be limited to consideration of …. Contamination” (Section 5.2.6)
“Potential occurrence of contaminated ground or groundwater that might be hazardous to people, the environment or the durability of construction materials” (Section 5.3.3)
Special procedures for handling storing contaminated samples (Sections 5.3.5)
Detailed descriptions of asbestos, other wastes, odour, hydrocarbon or other contamination (Table 11, Sections 6.2.11, 6.2.12, 6.4)
Other problems associated with some wastes include contamination, spontaneous combustion and emission of gas (Appendix C)
