If anyone is interested, prevailing wages are evaluated and maintained by the US Department of Labor, who posts updates to trade rosters by type of construction. This is established by the
Davis-Bacon Act.
Here is the latest wage determinations for a
Federal project like this...
http://www.wdol.gov/wdol/scafiles/davisbacon/tx17.dvb.
Since Federal funds
do not appear to be involved that would otherwise trigger such compliance, the City runs their own program along similar tenants...
http://www.austintexas.gov/sites/def...Compliance.pdf
And have a correspondingly similar roster of trades that are frequently included in contracts or agreements (or may be change ordered in as they may change over time)...
http://www.austintexas.gov/sites/def...7-23-12%29.pdf
Ultimately, the current one posted supersedes any previous determinations, but in general, the trades themselves do not change much between versions.
As it were, the process allows for contractors to submit requests for clarifications for specialty works to the DOL for further determination. Not sure if that applies in this case though.