OR/14/010 About the Pipe Leakage Impacts map

Dearden, R A, Tye, A M and Marchant, A. 2014. User guide for the Pipe Leakage Impacts. Nottingham, UK, British geological Survey. (OR/14/010)

Background

Buried utilities including pipes, drains and culverts enable the transport and supply of potable water, sewage and stormwater, and the conveyance of streams in channelized watercourses. Such assets are prone to leakage through cracks, holes and ineffective seals, resulting in wetting or saturation of the ground surrounding the asset. The failure of assets can occur for a wide variety of reasons including corrosion of the asset, ground movement (e.g. swelling clays or frost heave), pressurised flow or human-induced disturbance for example. Once failure has occurred, water leaking from assets can have a negative effect on the surrounding ground potentially causing leakage-induced ground movement. Depending on the scenario, it is possible that leaking water could:

• result in swelling of surrounding clay-rich deposits.
• increase the dissolution of soluble rocks leading to the formation of voids and associated subsidence.
• flush unconsolidated sediments into voids, or into the failed asset, resulting in the volume of voids around the asset increasing.
• alter the strength of the ground, which could increase compressibility, landslide or collapse.

In areas where ground movement can locally be affected by soil wetting or pipe leakage, the repair of assets should be prioritised to avoid additional instability that may threaten adjacent infrastructure.

The Pipe Leakage Impacts map indicates where pipe leakage may initiate or worsen ground instability. It considers which, and to what extent, ground stability hazards may be adversely affected by water leaking from pipes.

Who might require this map?

The Pipe Leakage Impacts map is relevant to those asset managers who maintain pipes, sewers and culverts that transport water. In particular the dataset will help:

• determine where leaks may cause ground instability
• prioritise the repair of leaking pipes.
• assess the risk posed to infrastructure adjacent to water pipes should they fail and leak.

The dataset is relevant to professionals involved in subsurface asset management in water companies, construction and other utility companies. It may also be of interest to solicitors, loss adjusters and the insurance industry. The map is derived from datasets at a scale of 1:50 000.

About the dataset

Overview

There are two versions of the map; summary and detailed. The contents of these are described in Section

Detailed datasets

The Pipe Leakage Impacts map (detailed) comprises one GIS layer called ‘Leakage’. It provides information on whether leaking assets could increase the potential for ground instability (Figure 1). It includes a summary map providing an overview of the extent to which leakage may increase ground instability. It also includes a further six sub-layers providing information about which hazards might be impacted.

Figure 1 An example of the GIS layer that considers the potential for leakage to increase the potential for ground instability.

Summary datasets

The Pipe Leakage Impacts map (summary) comprises one GIS layer called ‘Leakage_summary’. It provides information on whether leaking assets could increase the potential for ground instability (Figure 2). This summary map provides an overview of the extent to which leakage may increase ground instability, but it does not provide information on which hazards may be impacted.

Figure 2 An example of the summary GIS layer that considers the potential for leakage to increase the potential for ground instability.