Same thing happened to me. A couple of months ago I finally caught them. Almost Every Wed morning I would show up and one bay would be full of cooking grease and renderings. It would smell so bad that customers would leave and the car lot next
door would complain. It cost me plenty to hand dip out what I could and then get all the sewer lines cleaned out. If I didn't clean out the lines, they would clog within a couple of days. I filed a police report for vandalism each time. I got fed up and purchased a single camera and portable DVR for $500. Tue night I put cones in all the bays but one and put the camera in the one open bay. Sure enough they used the only open bay that night. They dumped 2 full trash cans (looked like 30 glln cans to me) and left two buckets of raw food scrap. I didn't get the license plate, but the next evening I drove up and down the street and found the truck at a taco stand / restaraunt combo. I called the law and before they arrived I threatened the owner with criminal charges for vandalism, reporting them to the local health department which would likely shut them down and reporting them to the Feds for illegal dumping and enviornmenal issues. I told the owner that he had cost me $10,000 and to make all his problems go away he could pay me $10,000. The cops arrived and they watched him write me a check and promise to never come back to my wash. I cashed the check the next morning. I have since learned later that the employee that was dumping was put on a payment plan to pay the owner back and was fired when he didn't pay.
I would post the video if I knew how or cared to learn.
Don't you love the carwash business!!