Chemical Plant Secondary Containment Upgrade
IBC Bunding Compliance — Environment Agency Pre-Inspection Response
Executive Summary
A chemical distribution company operating from a 3-acre industrial site in the North West of England received an Environment Agency (EA) pre-inspection notice with a four-week compliance window. The site stored 12 intermediate bulk containers (IBCs) containing WGK (Wassergefährdungsklasse) class 2 solvents — including acetone, IPA, and methyl ethyl ketone — with no adequate secondary containment in place. This case study details the site assessment, bund sizing calculations, product specification, and installation approach that achieved full compliance within the stipulated timeframe.
Background & Site Assessment
The site manager contacted our technical team following receipt of an Environment Agency Regulation 36 notice under the Environmental Permitting (England and Wales) Regulations 2016. The notice identified the absence of adequate secondary containment for bulk liquid chemical storage as a significant pollution risk to a nearby watercourse designated as a Site of Special Scientific Interest (SSSI).
Our NEBOSH-qualified technical consultant conducted a full site assessment within 48 hours of initial enquiry. Key findings included:
- 12 × 1,000L IBCs stored in two rows of six within a concrete-floored warehouse bay
- IBC contents: acetone (4 IBCs), isopropyl alcohol / IPA (4 IBCs), methyl ethyl ketone / MEK (2 IBCs), toluene (2 IBCs)
- All solvents classified as WGK Class 2 (clearly hazardous to water)
- Existing concrete floor had no chemical-resistant coating and featured unsealed expansion joints and drainage channels
- The drainage from the storage bay ran directly to a surface water outfall — a serious pollution risk
- No formal COSHH risk assessments on file for storage areas
- Personnel access routes between IBCs were not accounted for in any containment design
Bund Sizing Calculations
The 110% rule requires that secondary containment holds at least 110% of the capacity of the largest single vessel within the bunded area. However, best practice — and the EA's own guidance — recommends designing for 110% of the total stored volume when dealing with multiple vessels of flammable or water-hazardous liquids.
Total IBC volume: 12 × 1,000L = 12,000L
110% rule applied to total volume: 12,000 × 1.10 = 13,200L minimum bund capacity
Alternative (largest single vessel): 1,000L × 1.10 = 1,100L
25% of total: 12,000 × 0.25 = 3,000L
EA-recommended approach for WGK Class 2 solvents: 110% of total = 13,200L
Freeboard allowance (min. 150mm): adds approximately 800L additional safety margin
Final specified bund capacity: 14,000L
Given the layout constraints of the warehouse bay (approximately 12m × 6m available footprint), the design was split into two containment zones:
- Zone A (Primary): Fixed IBC bund system for 8 IBCs (8,000L content; 8,800L bund capacity)
- Zone B (Secondary): Fixed IBC bund system for 4 IBCs (4,000L content; 4,400L bund capacity)
- Access Areas: Portable chemical bunds covering the 2m gangway between IBC rows and all IBC access points
Product Specification
| Item | Product | Quantity | Capacity | Standard |
|---|---|---|---|---|
| IBC Bund Pallets (Zone A) | ÜHP Certified IBC Spill Pallet — 4-IBC Capacity, Polyethylene, Grating Included | 2 units | 4,400L each | ÜHP / EN 13160 |
| IBC Bund Pallets (Zone B) | ÜHP Certified IBC Spill Pallet — 2-IBC Capacity, Polyethylene, Grating Included | 2 units | 2,200L each | ÜHP / EN 13160 |
| Access Area Coverage | Portable Folding Chemical Bund — 3m × 1m, 300mm wall height, HDPE | 4 units | 900L each | PSSR compliant |
| IBC Connections | IBC Connector Pipes with drip-tight couplings | 12 sets | — | ATEX rated |
| Signage | Chemical Hazard & Secondary Containment Signage Pack | 1 set | — | ISO 7010 |
| Spill Response | Chemical Spill Kit — 120L absorption capacity, solvent-resistant granules | 2 units | 120L each | EN ISO 11925 |
Why ÜHP Certified? The ÜHP (Überwachungsgemeinschaft Hautschutz und Prüftechnik) certification is the German-originated quality mark widely recognised by UK Environment Agency inspectors and the Health and Safety Executive as confirming that IBC bund pallets have been independently tested for chemical resistance, structural integrity, and containment capacity. For WGK class 2 and above substances, EA inspectors frequently specifically request ÜHP certified equipment on re-inspection.
Installation Approach
A four-week compliance timeline required a structured project management approach. Our technical team coordinated directly with the site manager to deliver the following phased programme:
Week 1 — Supply & Preparation: All equipment ordered and confirmed for delivery by day 5. Site preparation work commenced: existing drainage channels within the bay were sealed with chemical-resistant epoxy grout, and the concrete floor was inspected and crack-filled ahead of bund installation. A temporary IBC storage arrangement was agreed to allow clearance of the bay.
Week 2 — Primary Installation: Zone A (2 × 4-IBC bund pallets) installed and levelled. 8 IBCs repositioned onto pallets using a 2-tonne counterbalance forklift. IBC connector drip-trays and coupling systems fitted. Zone B installation commenced.
Week 3 — Secondary Installation & Access Bunds: Zone B completed. Portable folding bunds installed across access gangways and IBC pump stations. All bund connections verified as drip-tight. Signage installed across all four walls of the storage bay.
Week 4 — Documentation & Final Checks: As-installed drawings produced. COSHH risk assessments drafted for all 4 solvent types stored. Emergency spill response plan written and laminated at exit points. Staff briefing conducted (12 personnel). Full photographic record compiled for EA submission.
✅ EA Re-Inspection Outcome
The Environment Agency re-inspection was carried out on day 27 of the compliance window. The assigned officer noted the following in their written report:
- Secondary containment: "Adequate and appropriately specified for the nature and volume of substances stored."
- Drainage controls: "Satisfactory — all drains confirmed isolated from surface water outfall."
- Documentation: "COSHH assessments and emergency response plan in place and accessible."
- Overall outcome: Notice closed. No further regulatory action required.
The site was issued with an EA Compliance Rating improvement from 'Red' to 'Green' within their sector compliance database.
Ongoing Compliance Maintenance
Following the successful re-inspection, we assisted the site manager in establishing an ongoing compliance maintenance programme. This included:
- Quarterly bund inspections: Visual check for cracks, deformation, or accumulated liquid; records kept on site
- Annual third-party inspection: Independent inspection and certification of all bund systems
- COSHH review schedule: 12-monthly review of all chemical risk assessments as part of ISO 14001 preparation
- Staff refresher training: Annual spill response drill and refresher briefing
- IBC change management: Procedure to ensure any new chemical added to site triggers a bund capacity review before receipt
The site has since received two routine EA visits under their Operator Monitoring Assessment (OMA) programme, both resulting in full compliance ratings. The site manager has reported that the clarity of documentation and the professional standard of installation were specifically cited by EA officers as evidence of a robust Environmental Management approach.
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