Mar 2016
Electricity Distribution and Electricity Transmission
Environmentally Acceptable Wood Pole Pre-treatment Alternatives to Creosote (APPEAL)
Mar 2016
May 2022
SP Energy Networks, Northern Powergrid, Scottish and Southern Electricity Networks and UK Power Networks
SPEN – Geoff Murphy (lead), UKPN – Matthew Reeves, NPG – Chris Goodhand, SHEPD /SEPD – Martin Lyster, David MacLeman
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Network Innovation Allowance
ED - Safety and health and environment
Stage 1: Literature Review

Literature review of alternative wood preservative types to select several which appear to be the most efficacious and most likely to be permissible for ‘Use Class 4 timbers’ (i.e. those with ground contact) under existing and future EU pesticide directives. This selection will be based on:

  • Proven anti-fungal efficacy

  • Longevity of anti-fungal effect (leach resistance etc.)

  • Absence of negative effects on treated timber physical properties (e.g. strength, conductivity, inability to take spikes)

  • Environmental profile

  • Simplicity of pole treatment (use of existing plant, seasoning requirements etc.)

  • Potential for upgrade of anti-fungal longevity using supplementary products

The review will include research papers, scientific texts and web searches for new preservative types being promoted by existing companies for Use Class 4 and other timbers. Contact will be made with pole treatment organisations to determine whether efficacious alternative products are already being considered and for what reasons. In addition, the efficacy of existing alternatives to creosote in other countries will be examined.

Stage 2: Accelerated Testing

The construction of a fungal cellar facility – microbiologically active soil bed, elevated temperature, elevated humidity and rainfall simulation – for accelerated testing of timbers treated with the selected preservatives under simulated field conditions to determine whether the literature claims of anti-fungal efficacy are borne out by test comparisons with creosoted timbers (high and low retention) under conditions representing at least 20 years of UK field exposure. Up to 600 samples can be accommodated, 500 are expected.

This project will potentially provide at least one novel preservative type that can replace creosote with or without supplementary products (e.g. ground-line wraps). Reduced concentrations of creosote will also be investigated and performance compared with controls, to include at least creosote and copper-chrome.

Stage 3: Final Report

Provision of a report detailing selection criteria, test results and recommendations including adoption of preservatives.

Stage 1: Literature Review

A detailed literature review of existing or novel preservative types offering at least 2 candidates (and low creosote alternative) as potential replacements for creosote (offering similar or greater decay prevention for timbers in Use Class 4 (ground contact)) for progression to testing at Stage 2. Recommended detailed project outline for Stage 2 (number of treatments, replicates and recommended duration of accelerated testing).

Stage 2: Accelerated Testing

Successful construction of fungal cellar facility and test bed deterioration results for timber posts/stakes treated with Stage 1 candidate preservatives and creosote (high & low retention).Pole lifetime will be predicted based on three samples of the specimens.

Stage 3: Final Report

Provision of final report detailing the outcomes of project Stages 1 and 2 and providing recommendations for further work with regard to any changes to existing treatment protocols and industry adoption.

  • The fungal cellar is constructed and operated successfully (i.e. provides the required high temperature – high humidity environment.

  • The test method is proven to be effective and valid.

  • The environmental variables are held constant across samples during the test.

  • The test provides estimated lifetimes for the samples, (whether preservatives, ground-line wraps or other treatments) with reasonable confidence intervals