Enforcement Policy for the iron mains risk reduction programme 2021 - 2026

The Health and Safety Executive (HSE) enforcement policy from April 2021 – March 2026 aims to reduce methane leakage from the Gas Distribution Networks (GDN) through the replacement of old iron mains pipes with new plastic pipes, through the Ofgem/HSE Iron Mains Risk Reduction Programme (IMRRP). Various policies to implement the IMRRP have been in place since 2002, all designed to decommission all ‘at risk’ iron pipes within 30 metres of a property in 30 years. In 2010, an independent report commissioned by HSE and Ofgem found that since the first cycle of the Enforcement Policy for the IMRRP (2002-2007), approximately 20% of the ‘at risk’ iron mains population had been decommissioned. 

 

The policy uses a three-tier approach to prioritise decommissioning. The three tiers of pipe diameter are:

• Tier 1: Pipes of 8 inches and below (approximately 80% of all “at risk” iron pipes). As in the 2013-2021 enforcement policy, each GDN operator will set a length of Tier 1 pipes to be decommissioned over the period of their approved programmes, which should be sufficient to ensure all Tier 1 pipes are removed by the end of 2032 or earlier. 
• Tier 2: Pipes above 8 inches and below 18 inches (approximately 15% of all “at risk” iron pipes) that are above the risk-action threshold set by GDN operators will either be decommissioned or, where possible, assessed for continued use if found to be in good condition or remediated to allow for lifetime extension. Pipes allowed to continue will be subject to condition monitoring arrangements.
• Tier 3: Pipes 18 inches and above (approximately 5% of all “at risk” iron pipes), which are least likely to fall within 30 metres of buildings. They will be subject to condition monitoring. Tier 3 pipes may still be subject to appropriate attention which may include but is not limited to decommissioning where a cost benefit analysis agreed with Ofgem is justified.

Over the period of each approved programme, HSE will require GDN operators to provide information on a quarterly and annual basis about length of tiers of pipelines decommissioned.

 

Ofgem funds this work through the RIIO-2 price control (as set out in the price control framework). Leakage rates for plastic pipes are around 99% lower than for metallic pipes.

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