BCUC Copy - March 2004 - PDF document

BCUC Copy - March 2004 Proposal Definition Sheet Proposal Title: Encapsulation of Wood Pole Butts – PHASE 4 Date: 2 January 2003 Recommending Working Group:Distribution #: P4303001 / 1355 Proposal Initiator: Summary of Problem/Opportunity: Preservative treated wooden poles carrying overhead lines are still the most cost effective meansof distributing power. Alternative support materials such as steel are competitive in price but areunclimbable, prone to corrosion problems and have very little BC content. Concrete poles areunclimbable, expensive, heavy and are currently available only in Washington state. Furthermoreindications are that the life cycle analyses for both alternatives are unfavourable compared to BC Hydro wooden utility poles are pressure treated over the full length to achieve a desiredchromated copper arsenate (CCA) preservative conrecent years, this has created a number of problems: Price of wood poles is increasing Wood preserving chemicals such as CCA are under increasing pressure fromenvironmental groups Alternate chemicals are more expensive and may not be as efficient for inground contact as the chemicals currently in use The proximity of treated poles in the vicinity of environmentally sensitive evaluate the merits of encapsulating wood polecost effective but complete assessment is still peof the previous project and is intended to complete the research. The work to date is summarized Previous Work: 1. Powertech Labs Inc. venture between BC Hydro and the BC Sciencematerials/treatments to select a model wrap/coating to assess the butt encapsulation technique. Abitumen wax impregnated synthetic wrap, which has been used by BC Hydro for many years forlong term protection of buried pipelines, was selected for the initial phase of the work. Inaddition to possessing excellent water repellency properties, the material could easily be applied In Phase II of the work, 160 – 0.5m long lodgepole pine posts were treated to varying levels withwrapped to 0.3 m with the bitumen wax impregnated synthetic wrap. Eighty posts were installedto a depth of 0.25m in a test plot at the Ingledow pole storage yard and the remaining posts wereinstalled in an accelerated weathering chamber under controlled temperature, humidity and soilmoisture conditions at Forintek Canada Corp. In addition, moisture-sensing electrodes were monitor potential moisture changes due to the treatment. Half of the poles were butt encapsulatedwith the synthetic wrap to a distance of six feet (1 foot above groundline) and all of the poleswere then installed in a test plot at the Ingledow pole yard. Six of the poles were also treatedinternally with borate solution or fused boron rods after being set. The posts and poles were inspected yearly and a detailed evaluation was performed after threeyears of aging. The results showed that the wrapping reduced the CCA losses to the soil by 35%internally treated with borates. The butt encapsulated posts showed a lower level of decay thanthe unwrapped control samples but the aging period was insufficient to make an accurateevaluation of the effectiveness of the treatment. A detailed fungal examination of the posts isrequired after 5 to 7 years aging in order to make this assessment. 2. Other Utility Experience For the past four years, a utility has employed a similar type of barrier system to extend the life oftheir new wooden poles. The system employed by a utility consists of heat shrink polymericymer. The system is much more expensive aspole but are still well above the estimated cost of $75 Canadian per pole for the Powertechsystem. This system has an opening at the base of the pole which would not be conducive to a“permanent” boron internal preservative treatment Summary of Project Objectives: To develop a wood pole preservative treatment that will provide 35+ years of servicewith a minimal use of potentially toxic chemicals Objectives Evaluation of a wrap/coating to reduce the preservative retention requirements for utility Minimize the loss of preservative to the environment and eliminate or reduce the need forremedial groundline treatments Summary of Benefits: Successful application of pole butt encapsulation over the preservative will: reduce the amount of preservative required to protect the below ground portion of thepole by minimizing chemical loss through leaching allow the use of localized preservative treatme eliminate or greatly reduce the need for remedial wood preservative treatments in thefuture that could result in savings of approximately $35 per treatment/pole ated savings are approximately $160k/year. Successful demonstration of the technique will allow the use of treated poles inenvironmentally sensitive areas. The butt encapsulation treatment would also substantially reduce contamination ofHydro pole storage yards, surrounding areas as well as field installation sites. substantially reduce future pole disposal problems Summary of Funding Requirements: Funding Requirements 95/96 96/97 97/98 98/99 99/00 03/04 Current Request 60,000 60,000 BC Hydro Funding 34,990 11,117 25,000 28,577 99,684 External Funding 32,675 20,000 20,000 72,675 Project Total 34,990 32,675 11,117 45,000 48,577 60,000 232,359 Phase 4. The work will entail the following tasks: Sample and analyse soil samples around the 160 posts and 24 poles todetermine CCA leaching losses. Remove and unwrap posts, assess wood for fungal decay. Assess the conditionand suitability of the model wrap material. Rewrap and reinstall posts. Determine pole moisture contents above and below the groundline. Remove the borate treated poles and determine the boron concentrations in thesoil and groundwater. Section the poles and determine the boron concentrationvertically and radially within the wood. Treat the remaining poles with borate preservatives. Phase 4 will be completed and a final report will be issued within one year.