Not sure what area you are driving from but the dump is in San Juan Capistrano. Drive South on Antonio parkway all the way to the end and that's where it's located.
If you are driving down the 5 exit as if you're going to drive over the Ortega Highway, when you see the equestrian fields on the right turn right at the next light (Antonio).
I think it's $10 to get in.
32250 La Pata Ave, San Juan Cpstrno
Landfill Link