Ask them,but I will say around 5 years,but have heard 2 to 3 years. The Team Lead from 2005/2006 stated that documentation needs to be held around 5 years.
I suggest that you apply at Sam's Club or the one in San Fernando and become aware of their policies and guidelines and how they are implemented. You will be amazed and shocked. They are not following the 7 Principles by Sam M Walton affectionately known as Mr. Sam.
I suggest that you call Sam's Club 6625 in San Fernando California and ask them to show the Surveillance Video Tape dated Saturday,April 21,2007 around 1 PM. A Tire Battery Center Associate was terminated on the allegations made by his co-associate that he was violently pushed. Monday,April 23,2007 the Club Manager,FJ,and Business Manager,EL, terminated the associate without following PD-57 that favors Sam's Club and not the associate since it does not allow any witnesses against management or the company.
Do a Yahoo search: Sam's Club 6625+management
Trust your judgement and do not allow even my response to influence to thinking.