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Storm Water & Sewer Network Hydraulics

Gravity storm water and foul sewer networks pipe by pipe, manhole to manhole: flows add up along the network (branches and junctions included), Manning capacity, exact partial-flow fill and velocity, invert levels, manhole depths, limit checks and recommended sizes - one report for both networks.

⚙️ Design limits and defaults

Storm water pipes

# Pipe Start MH Finish MH C paved A paved (ha) C green A green (ha) Ø (mm) L (m) Slope (1/a) n Start invert (m)
Enter only each pipe's own load - flows add up along the network by the manhole names. Start invert: needed for the first pipe of a branch; leave it empty on the other pipes and the level continues from the incoming pipe. Enter it as an absolute level, on the same reference as the cover levels.

Manhole cover levels

The list follows the manhole names in the pipe table - each cover level is entered once, as an absolute level (same reference as the invert levels). Depth = cover level − outlet invert level.
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Storm Water & Sewer Network Hydraulics

How the network is read
• Each row is one pipe: start manhole → finish manhole, with only its OWN load.
• Flow in a pipe = own load + flows of all pipes ending at its start manhole - the row order and numbering do not matter.
• A pipe whose start manhole receives nothing is the first pipe of a branch: enter its start invert.
• Empty start invert = continues from the lowest incoming pipe. Finish invert = start − L × S.

Hydraulics
• Manning full-bore capacity, exact partial-flow fill (y/D) and velocity for circular pipes.
• Checks: fill, min / max velocity, over capacity, outgoing pipe higher than incoming, smaller pipe after a larger one, soil cover.
• A larger standard size is proposed where a pipe fails.

Key Points:
  • Storm water and sewer networks on one page
  • Flows accumulate by manhole names - branches and junctions
  • Rainfall intensity in mm/h, L/s/ha or L/s/m²
  • Sewer loads per pipe (L/s, persons) or cumulative as entered
  • Exact partial-flow solution - fill and actual velocity
  • Paste rows straight from the Excel sheets
  • Manhole list to the Precast Manhole Take-off
  • PDF and CSV report
Calculation Steps:
  1. Enter all required parameters
  2. Click "Update Calculation"
  3. Review results and analysis