Preliminary Treatment (Headworks)Advanced 16 min read

Preliminary Treatment (Headworks): Advanced Headworks Design I — Screening & Grit Chamber Hydraulic Design

Full technical design criteria for headworks screening and grit removal systems: bar screen sizing standards, and the hydraulic design math behind horizontal-flow, aerated, vortex-type, and detritus grit chambers, with worked examples.

At Class A, the headworks stops being equipment you operate and starts being a system you can evaluate, troubleshoot against design intent, and — when the time comes — help specify for an upgrade. This guide works through the actual design criteria engineers use to size screening and grit removal equipment, drawn from real published design standards, with worked examples so you can see how the numbers actually connect.

Screening System Design Criteria

Screening devices are classified by the size of material they remove — the opening size of the screen itself. Published design references group them into three broad tiers:

Coarse screens (bar screens, trash racks): openings generally 6 mm (0.25 in) or larger. Trash racks run 38–150 mm (1.5–6 in); manually cleaned bar screens 30–50 mm (1–2 in); mechanically cleaned bar screens 6–38 mm (0.25–1.5 in).
Fine screens: typical o

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