Large Gravity Sewer Hydraulic Design Checker

Flow capacity, operating performance and configurable authority criteria

«This tool performs preliminary, single-reach, uniform-flow hydraulic checks against the selected design criteria. It does not replace network hydraulic modelling, project-specific authority requirements, professional engineering review or authority approval.»

Disclaimer. «This calculator is intended for preliminary engineering assessment only. It applies steady, uniform-flow calculations to a single circular sewer reach. It does not model hydraulic grade lines, backwater, surcharge propagation, storage, control structures, transitions, junction losses, dynamic rainfall response, pressure flow, hydraulic jumps, air movement, odour generation or network interactions. Authority criteria, pipe dimensions, roughness values and design flows must be independently confirmed for each project. Results do not constitute authority approval or certified design.»

Authority profile

Active profile

Project details

Project title

Reference / job no. Reach ID Prepared by Checked by

Notes

Pipe

Nominal diameter DN (mm) Actual internal diameter (mm)

Nominal DN is used for authority-table lookup. Actual internal diameter is used for all geometry and hydraulic calculations. Changing one does not overwrite the other.

Actual ID confirmed from the selected pipe product and structural class

Material Pipe class / stiffness class

Roughness method (part-full) Reach length (m) Manning n Colebrook–White k (mm)

Grade & sweep range

Selected grade — 1 : N Selected grade — %

Flattest plotted grade — 1 : N Steepest plotted grade — 1 : N

Drag the marker on either chart, or focus a chart and use ←→ (with Shift for fine steps) to adjust the selected grade.

Flow scenarios

Flows are entered in L/s and converted internally to m³/s.

Pumped inflow

No pumped inflow — TPF = 0

Total pumped flow TPF (L/s) Pump duty flow (L/s, optional) Concurrent pumps (optional)

Design criteria

Part-full equation Full-flow capacity Froude formulation

Acceptable grade range

Graph 1 — Flow and available capacity

Demand lines stay horizontal (fixed flow); capacity curves rise with grade. Grade axis: flatter left, steeper right (log spacing).

Graph 2 — Operating performance

Small-multiple panels share the grade axis with Graph 1 — one panel per metric, each with its own scale (no dual axes). Hover any panel for the full readout; the crosshair is synchronised.

At selected grade

Executive summary

Specialist-review triggers

Project checklist — tick any that apply (carried into the report)

Large Gravity Sewer Hydraulic Design Checker — preliminary screening tool. Single-reach, steady uniform flow only. Run runDevTests() in the browser console for the built-in regression and benchmark suite.

Large Gravity Sewer Hydraulic Design Checker

Acceptable grade range

Graph 1 — Flow and available capacity

Graph 2 — Operating performance

At selected grade

Executive summary

Specialist-review triggers

Project checklist — tick any that apply (carried into the report)

Preset matrix

Live calculation table — at selected grade

Worked substitutions — at selected grade

Design checks — result, margin and source

References