utility tracing

There is now widespread recognition that failing to identify utility apparatus prior to excavation has an impact not only on project costs and timings but also has major Health and Safety implications. Statutory Undertaker’s plans should be the starting point for any assessment as they give an indication of the type and amount of apparatus that may be present. The plans are rarely comprehensive and the accuracy can be variable and so further work in the form of a non-intrusive survey is usually required.

A simple non-intrusive utility tracing survey undertaken prior to the commencement of site work can provide clear and accurate results on the amount and location of buried services. This can help significantly reduce the health and safety risk, reduce the need for intrusive test pits, help avoid damaging the buried apparatus and minimise disruption to the site work and also to members of the public.

Section 60 of HSG47 ‘Avoiding danger from underground services’ published by the Health and Safety Executive in 2000 states that ‘the position of any services in or near the proposed work area should be pinpointed as accurately as possible by means of a locating device’. The guidelines detail what sort of devices should be used, including radio frequency locators (RFL) and ground penetrating radar (GPR), and requires that they should be used by suitably trained and experienced operators.

Where feasible both RFL and GPR surveys should be carried out in combination as this will provide the greatest chance of locating all types of buried apparatus, including metallic and non-metallic pipes and ducts, electricity cables, communications cables, drains, sewers and culverts. However, depending on the size of the survey area, the type and amount of apparatus that may be present or if only selected types of apparatus require locating then different levels of survey can be utilised.

It should be recognised that, due to limitations inherent in all current non-intrusive survey equipment, there can be no guarantee that all sub-surface features and apparatus can be identified. However, a non-intrusive survey can identify the majority of apparatus, within the depth limits of the equipment and it does allow clients to plan a project with greater confidence.

Phase Site Investigations Ltd can offer a number of categories of utility tracings services, offering the results in either a detailed accurate CAD plan or marked out on site. Where possible the type of apparatus will be displayed along with their depth where it can be measured.