Pottawatomie County Sheriff Greg Riat says Kramer was setting a plumbing line in a hole 10-feet deep. He says no one witnessed the collapse and it could have been as long as an hour before Kramer was found.
An autospy was being conducted Tuesday to confirm cause of death.
Kramer worked for Reid Plumbing and Heating of Manhattan.
OSHA confirms it is investigating the incident, as is standard procedure with work-related accidents. A spokesperson says the agency has six months to issue a report.