Seems that the term "scale" here has to do with the scraping/recycling industry or landfill business. It might be equivalent to "weighing" in this case. Follow these few links and see if you can get a better picture:

Scale House: A small building at the entrance of the property where customers pay for their dumped wastes. The weigh scale is located adjacent to the scale house. Restroom facilities are located in the existing scale house.
http://216.239.59.104/search?q=cache:YHCWxlD3zogJ:www.sccgov...

The scale house opened in 1989. Haulers are required to "weigh" in at the scale house upon entering the landfill with a load. An average of 320 tons/day is brought to the landfill, there is a maximum allowance of 535 tons/day. Approximately 95,000 tons are landfilled each year and it all weighs in at the scale house.
http://www.goglra.org/more_info.htm

I called the lady at the scale house who weighs the trucks.
http://www.google.com/search?q="scale house" "yard" -large&h...

Hint: Google "yard" and "scrap house" together... Good luck!