Technical library

Articles & guides

Technical articles for Australian and New Zealand engineers working on buried pipelines — AS/NZS 2566.1 structural design and gravity sewer hydraulics. More articles are added as they are written and verified.

Essential reading12 min
The E' Soil Modulus Problem in AS2566: What the Standard Gets Wrong
AS/NZS 2566.1 incorrectly equates embedment modulus and native soil modulus. For most projects this changes your deflection result by 20–40%. Here's how to apply the standard correctly.
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Topics covered
E'e vs E'n — the modulus confusion
Leonhardt correction factor ζ
Howard (1977) vs AS2566 Table 3.2
Look & Cameron (2018) consensus
Which E' to use on your project
Latest articles
Fundamentals
What Is a Pump's Best Efficiency Point (BEP)?
A plain explanation of BEP, the efficiency maths behind it, and how the pump checker builds a full working curve from a single BEP using the EPANET method.
5 min→
Fundamentals
BEP & Pump Curve Selection: Where the Duty Point Should Sit
What the best efficiency point is, what goes wrong far left or right of it, and the three effects that quietly move a duty point after selection — parallel pumps, VSD speed, and pipe ageing.
8 min→
Design check
Self-Cleansing Velocity & Tractive Force in Sewer Design
How sewers stay clean: minimum velocity vs the tractive-force method (τ = ρgRS), why shear beats velocity when flow is shallow, and the criteria Australian authorities actually apply.
8 min→
Reference
Minimum Grades for Gravity Sewers in Australia, by Authority
Fixed tables (DS50), calculated grades (Icon Water) and shear criteria (YVW) — how each authority sets the flat limit of the sewer grade window, with selected verified values.
7 min→
Fundamentals
Partially Full Pipe Flow: The d/D Charts Explained
Why a circular sewer carries its maximum flow at 93.8% depth, velocity peaks at 81%, and how to read the classic hydraulic-elements (Camp) chart.
8 min→
Reference
Water Corporation DS50 Gravity Sewers (DN150–600) Explained
Sewer Design Flow, grade and depth limits, allowable flows, standard sizes and the k = 1.0 mm roughness basis — DS50's hydraulic requirements, explained.
7 min→
Reference
AS2566.2 Table 5.6 Explained: GRP Allowable Deflection
The allowable installed deflection limit for GRP lives in Part 2, not the Part 1 design standard. What it governs, where it applies, and how it differs from the design deflection check.
5 min→
Design check
AS2566 Deflection Calculation: A Step-by-Step Worked Example
A complete DN315 PE100 gravity sewer design — from loads and soil modulus through the modified Iowa formula to the acceptance check. Every number reproducible in the calculator.
9 min→
Reference
AS2566.1 vs AS2566.2: What's the Difference?
One part is structural design, the other is installation. Which part of AS/NZS 2566 applies to your task, and how they work together on a real project.
9 min→
Reference
E′ Values Reference for AS2566 (Embedment & Native Soil)
Selected AS2566.1 Table 3.2 embedment (E′e) and native soil (E′n) modulus values by material and compaction — with guidance on applying them.
5 min→
Upcoming articles
InstallationComing soon
AS2566 Bedding Classes: Flexible Pipe Embedment Explained
How AS/NZS 2566.2 specifies embedment for flexible pipe — the zones, material and compaction requirements, haunch support, and how the specification sets E′ in design.
~9 min
Design checkComing soon
Buckling Under AS2566.1: The Two-Equation Check Explained
Eqs 5.4(4) and 5.4(5) — which governs, how to calculate the buoyancy factor Rw, and how to read the results.
~7 min
ComparisonComing soon
HDPE vs PVC vs GRP: Pipe Material Selection Under AS2566.1
Stiffness classes, long-term moduli, deflection limits, and allowable strain compared across the three main flexible pipe materials used in Australia.
~8 min
Free tool
AS2566 Design Calculator
Deflection · Buckling · Ring Bending Strain · Combined Loading — with full workings
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