I am building a 30×40′ shop building where I hope to restore some old Chevy pickups and trucks as well as some other oddball vehicles. What I need is some advice on capturing the oil and grease residue when I clean the old grease and grim from the vehicles, particularly the engine and rear axles. I am thinking about putting in a outside concrete apron to use when pressure washing the engine compartment and underside, but need to figure out how to separate out the oil and grease from the quantity of water I would use. Is this possible or am I going to have to figure out some other way to clean the engine (Q-tips and paper towels…). I did a web search and came up short. About the only thing I found was the following, which didn’t sound too promising. My situation is that I have 5 acres about 7 miles from town. I am on a private well and will be installing a septic tank.
Other Commercial Installations
Grease traps in garage, automotive, and other industrial/
commercial situations are now being phased out under the recent implementation of EPA’s rules on “Class V Injection Wells.†An injection well is any form of soil absorption system with the exception of single family and small cluster septic systems. Under the new rules, any new garage or automotive repair shop is allowed to have an onsite or septic system only for the domestic or toilet wastewater. The workshops must now operate without any form of floor drain. All fluids must be drained into appropriate containers for disposal or recycling off-site. Spills must be mopped up with suitable adsorbents and again disposed of off-site. Existing garage and workshop systems must be brought to zero discharge standards by 2003.
The rules for occasional washing of cars or a pay-for-service car wash are now equally stringent (Figure 3). Again classified as Class V Injection wells for subsurface discharge or as a point source discharge requiring a National Pollution Discharge Elimination System, NPDES permit, both systems will require potentially expensive treatment and monitoring to be maintained in service.
from: http://www.nesc.wvu.edu/nsfc/Articles/SFQ/SFQ_sp02_Web/SFQsp02_Q&A_GreaseTrap.html
Replies
Ah, for the good old days, where all you needed was a trap with two baffles--one high for liquid POL, and another, low, for any solids.
What you may want is a concrete "pan" over which you can set gratings. That would give you a surface to roll the vehicles out on (or a pad eye spotted for a winch, perhaps). You could then also stand on the gratings, too. After the wash up, any left over material would be in the pan to be dealt with later. (As I'm guessing you don't really want to wash the run off POL into your own land, per se.)
Some of the commercial waste folks will now also collect materials like washoff POL, as well as used motor & tranny oil. Whether they will accomodate a person's only periodic needs remains problematical. I know that my mechanic had to put signs on his hose bibs stating "Not for Wash Down Use"--not that he was, but the regulatory agencies just made it a requirement anyway.
If I get a chance, I'll ask a fellow I know who owns a d-i-y carwash--his drails will be covered under just this sort of regulation.