We've been to several no sewer or dump station parks over the years where "honey wagons" are the norm. Sometimes a once a week pump out was included in the site fee, with a charge for more often. We've also been to one municipal sewage treatment plant where RV's used the same dump routine as the septic tank pumpers. Just drive over a large grate and stop with your discharge pipe about midway and let it fly into a fast moving water canal below. An attendant was on hand with a high pressure hose to wash down any material left clinging to the grate.