Cleaning Dog urine smell out of dog runs

[mxgirl]

I maintain the dog run areas at the rv park I'm living at. They are small areas ,ground cover is a thin layer of pea gravel. They are used by 100s of dogs, and alot of owners don't clean their pet mess. So every night I start by picking up any poop/solid waste, then I rake the rocks to remove leaves, and to turn the rocks. After that I spray the areas with two different cleaners/chemicals (both are dog friendly) I use Eliminator which is supposed to get rid of the smell 5 or 6 days a week and I use Triple Two which is a disinfectant/cleaner/deodorizer or 2 days per week. I recently replaced the gravel in one of the three runs I handle, I applied garden lime and soaked it in before adding the new gravel. Ive also tried white vinegar. But even after doing all this the odor is HORRIBLE..any suggestions would be appreciated..also I've done some research online and found some say sweet pdz..feedback on this ?