we clean loads of them in the lakes,
we charge £25 inc cleaning the gutters out,
we can do 2-3 per hour 2 of us
we use tfr standard car cleaning brushes & rinse with i pressure washer on low pressure
its all mounted in my van so the sites love me cos i dnt use there water. i dnt tap into customers taps either which makes it quicker for me, we can usually do about 18 statics per day, its a brill wet day money earner,ive been doin them about 10 yrs now,