Keep an eye out for voids such as basements or drains, or spots of soft ground, which might break down when packed. https://Www.gvomail.com/redir.php?msg=a1bd7ceb3c44bef6c5249df2e382be54&k=a756067e79171aede411a9e7b15382b5463576e6246fec8d271283f9fba43f21&url=http://ezproxy.cityu.edu.hk/