Customer had full back up on septic line from house cleanout to septic cleanout. Could not free up blockage after numerous attempts with drain cleaning equipment. Returned with excavation equipment after utility locates were done. Removed retaining wall that was directly over septic inspection lids. Removed approximately 4 yards of soil and disposed off site. Inlet baffle pipe was directly against concrete inside of tank. This did not allow solids to drain and was the main cause of the backup. Previous repair was not installed correctly. Repaired pipe and tested drains. All flowing well at time of service. Met with landscaping company to go over location of wall repair so as not to block septic lids. Landscaping company will use some of the stones that were removed and handle the cleanup of the rest. They will replace fill as needed. Cleaned up sewage around house cleanout and disposed off site.