NG DH 15 PDF

This document details a methodology for determining whether existing, permanent ‘Civil, Structural and Building Engineering’ assets on National Grid substation sites are suitable to be re-used as part of a construction project. It shall not be applied to Overhead Line infrastructure (e.g. tower foundations). 

It has been developed to be utilised throughout the life of a project from the early stages as a feasibility tool to establish the general possibility that an asset might be suitable for re-use through to supporting the final design decision to incorporate the asset, or any part of it, into the permanent works. 

The basis of the methodology is a relative, risk based approach whereby the attributes of the existing item are compared directly with those of their new build equivalent and marked and summed accordingly. Provided the total score of the existing asset can be shown to fall within defined limits it shall be deemed suitable for re-use, if not it shall be replaced. 

For the purposes of this document the term ‘Civil, Structural and Building Engineering’ shall be applied to those permanent assets which fall into the following categories;

• Access roads

• Footpaths

• Drainage

• Oil containment works

• Fencing

• Site security

• Surfacing

• Ducts & trenches

• Buildings

• Site and Building services (excluding electricity and telecommunications services)

• Foundations

• Piling works

• Earthworks

• Ground Improvement/Stabilisation

• Plant support structures

• Holding down systems

• Fire protection & control systems

• Cable Tunnels

• Acoustic enclosures/barriers

• Site Lighting

• Landscaping

• Other enabling infrastructure (operational & non-operational) - e.g. retaining structures, bridges, culverts etc. 

Notwithstanding any of the conclusions that this methodology may reach National Grid shall reserve the right to explicitly determine whether or not an existing asset shall be re-used or replaced. It must be noted that in such a circumstance National Grid will be undertaking the role of ‘Designer’ under the Construction (Design and Management) Regulations (CDM 2007) and consequently such decision cannot be taken solely for unrelated reasons (e.g. economic and programme). The decision shall consider the full range of relevant factors but must be fundamentally based on specialist advice in relation to the Health and Safety requirements of CDM (i.e. integrity of the asset, hazards during construction and subsequent maintenance activities)