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Compliance & Reporting CIRIA C698 · GPP 5

Construction Phase Drainage

Temporary drainage and erosion control sizing for construction sites per CIRIA C698.

1
Site Information
2
Runoff & Risk
3
Drainage Measures
4
Compliance
5
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Site & Project Information

Site Characteristics

Runoff & Sediment Risk Assessment

CIRIA C698: Temporary works drainage design based on appropriate return period rainfall and sediment control factors per site characteristics.

Default: 50 mm/hr (1-year storm). Adjust for local climate data.

Source: EA May 2022 Climate Change Allowances Table 3 (peak rainfall intensity, surface water). Choose by time horizon + band: 2050s central 20 % / higher 25 % / upper 35 %, 2080s central 25 % / higher 30 % / upper 40 %, for 3.3 % AEP (30-year) sizing. For 1 % AEP (100-year) use the higher column (e.g. 2080s upper = 50 %). Check EA guidance for your river-basin district.
Risk Assessment Results
Peak Construction Runoff (Q) --
Adjusted Rainfall Intensity --
Estimated Sediment Load --
Overall Risk Rating --
Methodology

Peak Runoff (Q): Q = C × i × A / 3600, where C = 0.9 (bare soil), i = rainfall intensity (mm/hr), A = site area (ha)

Climate-Adjusted Rainfall: i_adj = i × (1 + climate allowance %)

Sediment Load: Based on CIRIA C698 Table 4.1 factors, considering soil type, slope, and proximity to watercourse.

Risk Rating: Composite of slope, area, soil permeability, and receptor proximity per GPP 5.

Temporary Drainage Measures

Select measures required for your construction phase. Sizing calculations update automatically based on site data.

Compliance & Environmental Management

Environmental Permit Checklist
Requirement Status Notes
Discharge requires EA consent? ACTION REQUIRED Depends on discharge rate and destination
Temporary works license required? ACTION REQUIRED Check EA guidance for works in/near water
Pollution Prevention Plan needed? YES Required for all construction sites >1 ha or sensitive location
Environmental monitoring plan? YES Water quality & sediment monitoring as per protocol
Emergency response procedures? YES Spill kit, hotline, immediate notification protocol
Monitoring Requirements

pH, suspended solids, turbidity, dissolved oxygen, temperature, oil & grease

Emergency Response Procedures
Immediate Actions on Incident:
1. Stop all construction works
2. Activate containment measures (spill kit)
3. Notify Environment Agency (0345 6035 694)
4. Initiate site remediation
5. Document incident and notify ecological consultant

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Document Includes:
• Project & site information
• Risk assessment results
• Temporary drainage measures sizing
• Compliance checklist
• Monitoring & emergency procedures
• CIRIA C698 & GPP 5 methodology reference
• Engineer signature block