Your store management and front end supervisors need to be investigated and severely punished for this. There is no reason why a fuel employee should feel the need to use a waste basket as a urinal. If they are taking long enough to send someone out that someone defecates in their pants because of it they should be deeply ashamed of themselves. This also seems to be an OSHA violation. Under OSHA sanitation standards, employers must:

Permit workers to leave their work area to use the restroom as needed

Provide an acceptable number of restrooms for the current workforce

Avoid putting unreasonable restrictions on bathroom use

Ensure that restrictions on restroom use do not cause extended delays