Okay so you’re going to have oil for sure.
A good degreaser will cost you, a lot of guys swear by EBC. My local guy makes his own product that works great too. $65 for 5 gallons. Do a test spot and figure how much product you minimally used in a 5x5 area. Take that, get the price per 5x5 area and extrapolate it for the whole lot. Add 10-15% (for the cost of getting the chemical, math errors, etc.)
An initial cleaning should cost more, on a maintenance schedule your efforts will make it easier down the road.
Any organic material (mold, mildew, dirt, grime, etc.) Sodium Hypochlorite is what you will want to use. Pool stores sell 10-12.5% figure out the price and again figure out how much a 5x5 area will cost you, extrapolate it.
These chemicals will do a majority of the cleaning for you, it’s truly amazing how well the dirt, grime, oil, mold, and mildew come off after being treated and being left to dwell.
If it’s oil you will need to use a reclaim, oil-water can’t go into the water table. Look up reclaim systems (super expensive) or fabricate your own. Another viable option is a sock-like filter. I believe they are called snakes, they filter out the sediment and oil only allowing water to pass. Make the investment and do it properly.
Commercial pricing can be tricky. Figure out your cost, figure out your hours-spent, and aim for atleast $100/hour.
You’ll get very good at eye-balling things over-time.
It’s a learning curve! Enjoy the journey!!
