Ms. Barnes, sorry to take so long replying to your post. I hope your question has already been answered. If your Housing Authority has 50 or more employees, the requirement for records retention is three years minimum for your self-evaluation plan as well as for any grievances filed. From the ADA Title II regulations:

35.105 Self-evaluation. All public entities are required to do a self-evaluation. However, only those that employ 50 or more persons are required to maintain this self-evaluation on file and make it available for public inspection for three years.

The Department of Justice also has assistance documents on its website that are helpful. Go to http://www.ada.gov/pcatoolkit/chap2toolkit.htm, and the retention requirement is at the bottom of the document. If you need further information, contact the Access Board at ta.access-board.gov or (800)872-2253 and speak to a technical assistant.

Consider keeping the records for more than three years if you have to refer back to an old case or a recurring issue.