Pharmaceutical API Manufacturing Plant in Dublin, Ireland

Pharmaceutical API Manufacturing Plant in Dublin, Ireland

Scenario

A new active pharmaceutical ingredient (API) manufacturing plant is under construction on a greenfield site in the Dublin Industrial Zone. Secondary containment is required for solvent storage (acetone, methanol, ethyl acetate) per EU Directive 2004/35/EC (Environmental Liability Directive) and Irish EPA Guidance Note GN03. Constraints include high water table (1.2 m below surface), strict groundwater protection requirements, and limited excavation depth due to proximity to existing utility corridors.

Given Data

• Volume of the largest tank: 18.7 m³ (stainless steel horizontal tank storing methanol)
• Projected area of the containment sump: 42.5 m² (defined by bund wall footprint; constrained by adjacent HVAC skid and fire lane)
• Local rainfall intensity: 28 mm/hour (Met Éireann 20-year 2-hour storm, adjusted for site microclimate using local gauge data)
• Design storm duration: 2 hours (per Irish EPA GN03 Table 4.2 for low-risk industrial sites with rapid drainage)

Calculation

The required secondary containment volume is computed as:

Secondary Containment Volume = Volume of largest tank + (Rainfall intensity × Duration × Sump area)

Convert rainfall intensity to meters/hour: 28 mm/hour = 0.028 m/hour

Rainwater accumulation = 0.028 m/h × 2 h × 42.5 m² = 2.38 m³

Total required volume = 18.7 m³ + 2.38 m³ = 21.08 m³

Rounded to two decimal places per tool specification: 21.08 m³

Result and Decision

A prefabricated, double-walled polyethylene sump (UN-certified, FDA-compliant resin) rated for 22.0 m³ was installed. Due to the high water table, the sump was anchored with ground anchors and fitted with a continuous hydrostatic pressure relief system connected to a monitored overflow tank. Leak detection used interstitial monitoring with optical fiber sensors along weld seams.

Lesson

In low-rainfall but high-groundwater environments, rainwater volume may be small — but hydrostatic uplift risk dominates design. Always perform buoyancy analysis in addition to sump volume calculation; this project’s 22 m³ sump required 14.3 kN of anchorage force to prevent flotation during saturated conditions.