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Develop list and consumptiom requirements of all existing and new users for project.
Investigate location and size of existing utility piping in the project area. Review existing P&ID , flow sheets and/or existing metering devices to determine what is curently being used versus amount available. Always field investigate, especially brown field sites. Existing drawimgs are a good starting point for review, however, the drawing may not be reflective of various changes over the years. The existing conditions may warrant the need to field install pressure and flow gauges on existing piping to determine actual conditions.
If the new project consumption requirements exceed existing utility amount available then you will need to locate or provide new souce of ample supply. Depending on your situation, the last sentence requires thorough investigation as not to "starve or cut off supply" to users downstream of the project area.
Upon completion of all the above, you will be able to create a "road map" as how to get to where you need to be as compared to where you currently are. In other words, you will be better informed as how to determine your scope of work. Price accordingly. The above is general idea as to what is involved.