Hey guys. If i were a municipality needing major overhaul of systems/equipment, what companies or engineering firms would i go to to have this done? I'm having trouble getting this information. What is typically the route the plant would take?

It depends on a lot of factors but typically an agency will solicit bids or requests for proposals for a piece of equipment or services and depending on the response the lowest bidder would receive notification that they've been selected.  An agency can do this internally or submit their request to a central networking bid system such as

http://www.govbids.com/scripts/theNetwork/Public/Info/Regoptions.asp

As a vendor or service provider you would submit your company's name to receive notifications from such a central bidding networking system.  You should probably call several agencies or visit their websites to see how they handle this.  For example:

http://www.ieua.org/departments/CAP/doing.html