brown
building
business
construction
dig
ditch
dug
earth
energy
excavation
extract
extracting
forest
fuel
gas
grass
green
ground
industrial
industry
land
line
metal
nature
oil
outdoor
petrol
pipe
pipeline
power
red
road
round
soil
steel
supply
technology
terrain
tracks
tractor
transport
transportation
tube
vehicle
water
wire
work