1970’s – King Inquiry 1995 – Maintain Safety Level - HSE 2001 – Precautionary Approach - HSE

1. North London Network Management Unit Why do we replace gas mains ? • 1970’s – King Inquiry • 1995 – Maintain Safety Level - HSE • 2001 – Precautionary Approach - HSE Neil Shaw/v.1./30 January 2002

2. North London Network Management Unit Mains Incidents 1976 to 2001 Trend Line

3. North London Network Management Unit Regional Breakdown Neil Shaw/v.1./30 January 2002

4. North London Network Management Unit Minimising Disruption • Ofgem have capped our allowed costs for 2002 – 07 = Incentive to reduce cost= reducing • excavations • Decommission only where possible ratio target 1:1.1 lay:decommission • Use no – dig techniques where possible typically50 – 60% achieved Neil Shaw/v.1./30 January 2002

5. North London Network Management Unit Summary • Safety • Precautionary approach applied by HSE under Pipeline Safety Regulations • Regulatory Incentive to reduce cost = reduceexcavation • Aim to minimise disruption by use of non digtechniques Neil Shaw/v.1./30 January 2002

6. North London Network Management Unit Neil Shaw/v.1./30 January 2002

7. North London Network Management Unit Neil Shaw/v.1./30 January 2002