When I first started out in civil engineer, I worked in Edmonton. Edmonton was a wonderful place to learn about city planning and land development because they have such clear standards for everything. In fact, I still refer to their guidebooks regularly. These guides not only have standards, but tons of simple and clear illustrations about how to meet them, such as the lot grading standard (page 84).
Part of the planning process was something called a Neighborhood Design Report. The city was organized into big chunks- it isn't like the work I did here with small bits and pieces- everything was studied on a large scale before the phases were done in detail.
A significant part of the NDR was designing major and minor storm systems. I was typically charged with setting some very conceptual road elevations and sketching out pipe runs with green marker.
After a few iterations, I'd measure the green lines with a scale and make a big excel spreadsheet detailing how one manhole flowed into another (Edmonton required manhole to manhole connections, inlets had their own lines.) Then, I'd put it all into CAD as polylines and circles, measure out some subcatchments contributing to each manhole, and add manning's equation to the spreadsheet.
This is what the CAD drawing would have looked like.
We'd also come up with a drawing that showed how the stormwater would move overland in a "major" event.
It was all very fun, and due to my fondness of both complicated excel formulae and pentel sign pens, this was one of my favorite projects to work on. Thinking about it now though, it was really an entirely manual and static process. We were pretty good about using the spreadsheets and CAD drawings as a kick off to the more detailed design later on, but they were so very different.
My NDR drawings we so sketch that they really weren't immediately useable. I almost want to go back and do some with Civil 3D, because it would be so much more fun.
I don't remember how we came up with the surface information- maybe survey. Now, we could go grab Google Earth to start, then replace it with aerial topographic data later or a survey. We could drop in some really rough corridor models- skipping the cul-de-sacs and intersections at first, and place a few pipe networks or maybe just alignments as we iterated, Then push the pipe networks out to Storm Sewers for analysis and design, then back into Civil 3D to make a table. When the NDR was approved, the whole thing could be immediately consumed by the detailed design teams.
For the major storm plan- slope arrows, elevation analysis, water drop and other tools would have made things a lot easier. I'm also thinking about all of the other exhibits we and the planning department had to make manually with hatching and mark ups... Things would be easier now for sure.
If anyone out there is using Civil 3D for this type of planning, feasibility and drainage study- drop me a line. I'd love to hear what you're up to.