On-Site Detention (OSD) — Simplified Sizing

Ref: MSMA 2nd Edition (2012), Chapter 5 §5.8.3; Table 5.A1 (Five Regions)

This simplified procedure uses MSMA 2nd Edition Table 5.A1 (Five Design Regions). Values are linearly interpolated across impervious bands (25, 40, 50, 75, 90 %). For sites in one of the 18 major towns listed in Table 5.A2, town-specific values should be preferred. Design storm ARI is 10-year per §5.8.1(a).

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PSD (L/s) = PSD_lps/ha × A ; SSR (m³) = SSR_m³/ha × A

Ref: MSMA 2nd Edition (2012), Chapter 5 §5.8.3; Table 5.A1 (Five Regions)

Design Region (Fig 5.A1)

Selangor, KL, Putrajaya, Perak coast (non-highland)

Terrain / Slope

Slope 1:875 to 1:1999

Impervious Area (%)

Percentage of project area that is impervious (valid 25–90 %)

Project Area (ha)

Site area that drains to the OSD facility

Permissible Site Discharge (PSD)

—L/s

Engineering aid only — final design must be endorsed by a registered PE under BEM.

PSD (m³/s)

—m³/s

Engineering aid only — final design must be endorsed by a registered PE under BEM.

Site Storage Requirement (SSR)

—m³

Engineering aid only — final design must be endorsed by a registered PE under BEM.

SSR with 20 % landscape allowance (§5.3.1)

—m³

Engineering aid only — final design must be endorsed by a registered PE under BEM.

Disclaimer: This output is an engineering calculation aid only and does not constitute a final or endorsed design. All designs submitted to Malaysian authorities must be endorsed by a registered Professional Engineer (PE) under the Board of Engineers Malaysia (BEM) in accordance with the Registration of Engineers Act 1967.