I would contact your Local USDA/NCRS office. They specialize in agricultural waste management. I used to work for them many moons ago. We never used channels for management. We did use waste retention ponds where you stored the waste and used a grinder pump to pump the sludge into a tank on a tractor where it was applied to agricultural fields. if the solid have been removed, you can spray irrigate the effluent. Google Living Filter. Hope this helps.