PE Exam Practice Problem #49: Water Resources | Stormwater Collection - Sewer Invert

Welcome to SolvedIn6: Free practice problems for the Professional Engineering Exam! Each question is styled after those created by the NCEES, and is usually solved in under 6 minutes, which is the average time you will have to solve each question on the Professional Engineering Exam.
In this problem, a new maintenance dropshaft is going to be installed between two existing maintenance holes. We need to find the height of the dropshaft such that it reaches 12 inches below the invert (bottom) of the pipe and also reaches the surface of the ground.
So while this looks like a water resources/sewer problem, you may be happy to know that it can be solved using only geometry. If for some reason you love water resources but hate geometry, then I guess you’ll feel the opposite about it. Anyway, lets solve it as follows:
Step 1: Find the existing slope of the sewer (rise over run).
Step 2: Find the invert elevation at new station B.
Step 3: Find dropshaft B’s invert (bottom) elevation.
Step 4: Find the height of dropshaft B by subtracting the ground surface elevation from the invert (bottom) elevation.
If you would like more Water Resources practice problems, please check out the rest of the playlist which this video is part of.
Please note that newer versions of the reference manual may have been released since this video was recorded. The search terms are usually still correct, but the page numbers listed in the video will be different.

[@jessicagray6944]

The math is correct but you have the slope written as 0.414 rather than 0.0414. Your videos are such a great help, thank you for all that you do!

[@SolvedIn6]

Great catch! Sorry about that and thank you for pointing it out!