Author version of paper published as: Carroll, Steven and Goonetilleke, Ashantha (2005) Assessment of high density of onsite wastewater treatment systems on a shallow groundwater coastal aquifer using PCA. Environmetrics 16(3): 257-274 Copyright 2005 John Wiley and Sons, Ltd. ASSESSMENT OF HIGH DENSITY OF ONSITE WASTEWATER TREATMENT SYSTEMS ON A SHALLOW GROUNDWATER COASTAL AQUIFER USING PCA STEVEN CARROLL AND ASHANTHA GOONETILLEKE School of Civil Engineering, Queensland University of Technology 1