Alcoa - Subject to local approval, limits the duration or exclusive contracts to 25 years instead of 50 years; clarifies procedure for removing a city commissioner; removes requirement for commission to adopt a pay plan for city employees; increases the purchasing limit, from $5,000 to $10,000, that does not require a public bid; updates references to Tennessee Code Annotated; makes other various revisions. - Amends Chapter 510 of the Private Acts of 1919; as amended.