There is a thing called a truck mat. It has inflatable edges and allows trucks to be driven over the sides and still contain the water. You would then have to suck it out to be properly reclaimed and dealt with. I can't find the site that has them but at last check they sell for around $500-$600 or so. Make sure they are willing to pay for that kind of equipment use before starting anything with them.

Larry Bicknell
Mid Valley Mobile Pressure Washing


midvalleymobile@comcast.net