The City of Pleasanton offers FREE sand and sandbags for residents and businesses concerned about flooding. Fill up and take home sandbags at any time. The city has a sandbag filling station in the parking lot of the Operations Services Department, located at 3333 Busch Road. Please bring your own shovel or something you can use to scoop sand into bags.
For more information about what to do before, during, and after a storm, check out the City of Pleasanton's Emergency Preparedness page here: http://www.cityofpleasantonca.gov/gov/depts/os/emergency_preparedness.asp