Although the wood pole has been the utility structure of choice for many decades, there are increasing responsibilities that demand attention from the specifying engineer. While cost is always important, the engineer can no longer ignore the issues of public exposure to treated wood materials and their ultimate disposal in this environmentally sensitive time. This sense of a “cradle to grave” responsibility didn’t exist a decade ago. Beyond evaluating cost, availability and climbability, today’s engineer must also consider environmental alternatives to the traditional wood preservatives: creosote, pentachlorophenol PCP) and chromated copper arsenate (CCA).
While recognized as an effective wood preservative for more than 100 years, copper naphthenate is now emerging as the leading alternative for utilities facing increasingly stringent environmental regulations since the chemical's reintroduction to the industry in the 1980's. The reintroduction of copper naphthenate coincided with increasing environmental awareness in the utility and wood preservation industry as the Environmental Protection Agency (EPA) promulgated a variety of restrictive regulations greatly affecting both industries.
These regulations forced some treaters out of business, while others made major capital improvements to address environmental problems. In 1972 the EPA classified copper naphthenate as a general use pesticide and a recent review1 of the regulatory status of copper naphthenate revealed that it was:
The research and case study presented here provide substantial evidence that copper naphthenate is one of the most environmentally sensitive and effective wood preservatives available to the industry today. Now is the time to reevaluate copper naphthenate as your pole preservative.
Lessons Learned
When copper naphthenate was first introduced as a pole preservative, isolated treating plant product handling and emulsion problems led to some early pole failures. Some of these poles failed within eighteen to thirty-two months of service, faster even than untreated poles would be expected to fail. Freeman and Amburgey2 found untreated SYP poles fail at 4.5 years in AWPA Hazard Zone 4 in central Mississippi. However, the extent and nature of the copper naphthenate treated wood pole failures were widely exaggerated. To put things in proper perspective, a recent inspection and boring program3 that randomly surveyed over 400 copper naphthenate poles installed by 12 different utilities in all AWPA decay hazard zones of the US showed a failure rate of less than 1%, or essentially the same rate as other oil-borne treatments.
An even more telling result is that the incidence of premature failures has essentially disappeared. A recent review4 concluded that many of the early failures were due to improper pretreatment conditioning and other factors that would have caused early failure regardless of the preservative used. A significant point illustrated in Figure 1 is that, for one treater, failures occurred during the early production and could be attributed to “learning curve” problems. Those problems were caused by the chemical manufacturer and the wood preservation facilities not knowing how best to manufacture and treat with the product.
It is important to note that over 1.2 million copper naphthenate poles have been installed in the last decade, and the overwhelming majority of those poles are still performing. In fact, there have not been more than 3 failures reported by any treater for poles produced after 1994. Additionally, to the best of the authors’ knowledge, early failures have only been found in southern pine poles, and of these only poles treated to the lowest AWPA retention have been implicated.
Interviews with utilities, treaters, inspection companies, pole sellers, and industry experts and previously issued research revealed that the circumstances of each case are not all the same. The premature failures are thought to be caused by one or more of the following conditions:
No allegation has ever been made that copper naphthenate is itself an ineffective preservative. On the contrary, every case starts with the assumption that poles properly treated with copper naphthenate will meet the industry life expectancy of 35+ years. In fact, with a proper inspection and remedial treatment program, oil-borne preservative treated poles may well last over 80 years.
It is unfortunate that failures like this occur, but failures have happened with all preservative treatments. However, steps have been taken to avoid future premature failures with copper naphthenate. Since 1995, the overall quality of the copper naphthenate treated poles has improved as treaters and chemical suppliers have learned to control water emulsions and treatment variables. As of this date, over 1 million poles have been treated with copper naphthenate since 1988, and less than 4,000 have been cited as having early decay problems, with most of those in the early 1990s as mentioned previously. These 4,000 failures out of >1,000,000 poles is certainly a lower rate than one might expect (less than 0.5%) based on a normal distribution curve from a 35 year mean (median) service life for a wood pole.
Long Term Effectiveness
Numerous field trials have documented the long-term performance of copper naphthenate, and a review of some 27 different studies showed comparable efficacy of copper naphthenate and PCP at their respective AWPA retentions5. A small sampling of this data in Figure 2 compares copper naphthenate performance data from three field trials to PCP at or near their respective AWPA minimum retentions for southern pine. In two stake tests using a fuel oil carrier and heavier oil, the copper naphthenate and PCP performance are virtually identical. In the third test of posts by the USDA Forest Products Lab, copper naphthenate and PCP performance are almost the same over the 27-year study.
Obviously, these tests were initiated some time ago, but two recent papers reported tests conducted with today’s oils. Nicholas and Freeman6 reviewed 11-year stake tests in central and southern Mississippi and concluded that copper naphthenate and PCP provide the same degree of protection in four different oil carriers. Barnes and Freeman7 reported no insect or fungal attack on any of 84 copper naphthenate test poles after 12 years of exposure. Clearly, copper naphthenate poles can be used without fear of reducing the longevity or integrity of the system.
Life Cycle
As stated earlier, product stewardship is being increasingly emphasized in the chemical industry. The most widely used product stewardship program is the American Chemical Council’s Responsible Care® program. Simply put, product stewardship dictates that a supplier has a responsibility to ensure that his product is properly used and properly disposed of when its life cycle is complete. This “cradle to grave” responsibility adds a new aspect to the specifier’s job and requires that he address the issue of ultimate disposal of the product. This is becoming a concern with some preservatives, but copper naphthenate poles can be disposed of in sanitary landfills.
Furthermore, there is no indication that disposal of copper naphthenate will be restricted in the future since it has such benign health and safety traits.
Cost and Availability
Copper naphthenate is similar in cost to other oil-borne treatments due to the recent manufacturing economies. The newest copper naphthenate manufacturer is basic in naphthenic acid production so one can predict that the price will be stable with no exaggerated upsets due to transient economic factors. Both southern pine and Douglas fir can be treated with copper naphthenate in plants in the Southeastern and Western United States with a wide range of sizes and classes available.
PG&E Case Study
In a recent interview, Mr. Pete Loechner, retired Senior Standards Engineer of Pacific Gas and Electric, made the following comments on PG&E’s specification of copper naphthenate poles:
“Today’s utilities face challenges from three major groups: the environmental agencies to ‘keep it healthy’; the governmental agencies to ‘keep it safe’; and the utilities and their rate payers to ‘keep it economical.’ These challenges are becoming more severe due to the latest disposal problems for treated wood products.
“But how does the utility standards engineer know which wood preservative to specify? He is familiar with the various physical properties of the soils in his service area. He knows the seasonal climate conditions. Above all, he has knowledge of all approved AWPA preservatives gained by discussing his needs with the preservative treaters and the manufacturers of the preservatives.”
In 1987, Loechner began a new career as PG&E’s Standards Engineer for their wood products. PG&E were purchasing poles treated by suppliers of the three major preservatives. Loechner stated, “On my first day, Supplier X informed me that FIFRA, RCRA and EPA would increase various restrictive regulations that would eliminate preservatives Y & Z. The next day, Supplier Y instructed me that preservatives X & Z would be soon eliminated by the above agencies. One can imagine the panic that occurred for PG&E when Supplier Z related that preservatives X & Y would soon be discarded.
At this time, a fourth preservative for poles was introduced to us: copper naphthenate, a preservative approved by all governmental agencies and listed in the AWPA Standards. Copper naphthenate is also used as a preservative to treat the interior wood of beehives and veterinarians used the preservative to bathe the hooves of animals. Being located in a strict environmentally monitored area, California, PG&E took a thorough look at copper naphthenate.”
PG&E, various pole suppliers, and representatives from the copper naphthenate manufactures performed the following tests:
“The results of these tests prompted PG&E to select copper naphthenate as its major preservative for treating wood poles.”
Mr. Loechner closed by stating, “During my tenure as PG&E’s Senior Standard’s Engineer, I received no complaints from lineman, warehousemen, and/or second and third parties pertaining to copper naphthenate. I believe copper naphthenate poles assist in giving utilities the biggest bang for their buck, a savings that is passed on to the ratepayer.”
Increasingly the utility industry has looked to alternate materials such as concrete, metal or fiberglass poles to address health concerns with treated wood. This re-evaluation of copper naphthenate shows it to be an effective, cost competitive, clean, safe wood preservative that keeps the long-time favorite, the wooden utility pole, preferable to those higher cost alternatives. In short, copper naphthenate is the “customer friendly” preservative for all customers: the public, the purchasers and you, the specifying engineer.
REFERENCES
Note: Copies of the references and other information regarding Copper naphthenate can be obtained at: www.merichem.com.
* The Douglas fir species is very popular in the western section of the country. It has the same strength ratings as Southern Pine, but lacks the depth of the sapwood as found in the pine (deeper sapwood gives more penetration of preservative). However, Douglas fir can be through-bored at any level allowing full penetration of a preservative into the heartwood.
While recognized as an effective wood preservative for more than 100 years, copper naphthenate is now emerging as the leading alternative for utilities facing increasingly stringent environmental regulations since the chemical's reintroduction to the industry in the 1980's. The reintroduction of copper naphthenate coincided with increasing environmental awareness in the utility and wood preservation industry as the Environmental Protection Agency (EPA) promulgated a variety of restrictive regulations greatly affecting both industries.
These regulations forced some treaters out of business, while others made major capital improvements to address environmental problems. In 1972 the EPA classified copper naphthenate as a general use pesticide and a recent review1 of the regulatory status of copper naphthenate revealed that it was:
- NOT listed in the Clean Air Act
- NOT classed as a hazardous waste in RCRA
- NOT regulated under TCLP in RCRA
- NOT regulated as restricted use in FIFRA
- NOT listed in the Clean Water Act or CERCLA (Superfund) hazardous substances for spill reporting.
The research and case study presented here provide substantial evidence that copper naphthenate is one of the most environmentally sensitive and effective wood preservatives available to the industry today. Now is the time to reevaluate copper naphthenate as your pole preservative.
Lessons Learned
When copper naphthenate was first introduced as a pole preservative, isolated treating plant product handling and emulsion problems led to some early pole failures. Some of these poles failed within eighteen to thirty-two months of service, faster even than untreated poles would be expected to fail. Freeman and Amburgey2 found untreated SYP poles fail at 4.5 years in AWPA Hazard Zone 4 in central Mississippi. However, the extent and nature of the copper naphthenate treated wood pole failures were widely exaggerated. To put things in proper perspective, a recent inspection and boring program3 that randomly surveyed over 400 copper naphthenate poles installed by 12 different utilities in all AWPA decay hazard zones of the US showed a failure rate of less than 1%, or essentially the same rate as other oil-borne treatments.
An even more telling result is that the incidence of premature failures has essentially disappeared. A recent review4 concluded that many of the early failures were due to improper pretreatment conditioning and other factors that would have caused early failure regardless of the preservative used. A significant point illustrated in Figure 1 is that, for one treater, failures occurred during the early production and could be attributed to “learning curve” problems. Those problems were caused by the chemical manufacturer and the wood preservation facilities not knowing how best to manufacture and treat with the product.
It is important to note that over 1.2 million copper naphthenate poles have been installed in the last decade, and the overwhelming majority of those poles are still performing. In fact, there have not been more than 3 failures reported by any treater for poles produced after 1994. Additionally, to the best of the authors’ knowledge, early failures have only been found in southern pine poles, and of these only poles treated to the lowest AWPA retention have been implicated.
Interviews with utilities, treaters, inspection companies, pole sellers, and industry experts and previously issued research revealed that the circumstances of each case are not all the same. The premature failures are thought to be caused by one or more of the following conditions:
- Pretreatment (incipient) decay.
- Improper sterilization/conditioning/drying.
- Inadequate copper penetration and retention, including typical Gaussian distribution causing under (sub-threshold) treatment.
- Improper or insufficient inspections.
- Low retention levels used in high AWPA hazard zones.
- Chemical formulations containing stable water emulsions that prevent effective and uniform penetration of copper naphthenate into the pole.
- Possible use of synthetic or other nonnaphthenic acids that do not conform to AWPA Standard P8 for copper naphthenate and possibly contributing to a propensity to form stable emulsions.
- The “learning curve” described by McIntyre5,6 where both treaters and the manufacturer did not initially know how to effectively handle and use this new preservative system, thinking it would effectively be the same as either penta or creosote in handling characteristics, including emulsion remediation.
No allegation has ever been made that copper naphthenate is itself an ineffective preservative. On the contrary, every case starts with the assumption that poles properly treated with copper naphthenate will meet the industry life expectancy of 35+ years. In fact, with a proper inspection and remedial treatment program, oil-borne preservative treated poles may well last over 80 years.
It is unfortunate that failures like this occur, but failures have happened with all preservative treatments. However, steps have been taken to avoid future premature failures with copper naphthenate. Since 1995, the overall quality of the copper naphthenate treated poles has improved as treaters and chemical suppliers have learned to control water emulsions and treatment variables. As of this date, over 1 million poles have been treated with copper naphthenate since 1988, and less than 4,000 have been cited as having early decay problems, with most of those in the early 1990s as mentioned previously. These 4,000 failures out of >1,000,000 poles is certainly a lower rate than one might expect (less than 0.5%) based on a normal distribution curve from a 35 year mean (median) service life for a wood pole.
Long Term Effectiveness
Numerous field trials have documented the long-term performance of copper naphthenate, and a review of some 27 different studies showed comparable efficacy of copper naphthenate and PCP at their respective AWPA retentions5. A small sampling of this data in Figure 2 compares copper naphthenate performance data from three field trials to PCP at or near their respective AWPA minimum retentions for southern pine. In two stake tests using a fuel oil carrier and heavier oil, the copper naphthenate and PCP performance are virtually identical. In the third test of posts by the USDA Forest Products Lab, copper naphthenate and PCP performance are almost the same over the 27-year study.
Obviously, these tests were initiated some time ago, but two recent papers reported tests conducted with today’s oils. Nicholas and Freeman6 reviewed 11-year stake tests in central and southern Mississippi and concluded that copper naphthenate and PCP provide the same degree of protection in four different oil carriers. Barnes and Freeman7 reported no insect or fungal attack on any of 84 copper naphthenate test poles after 12 years of exposure. Clearly, copper naphthenate poles can be used without fear of reducing the longevity or integrity of the system.
Life Cycle
As stated earlier, product stewardship is being increasingly emphasized in the chemical industry. The most widely used product stewardship program is the American Chemical Council’s Responsible Care® program. Simply put, product stewardship dictates that a supplier has a responsibility to ensure that his product is properly used and properly disposed of when its life cycle is complete. This “cradle to grave” responsibility adds a new aspect to the specifier’s job and requires that he address the issue of ultimate disposal of the product. This is becoming a concern with some preservatives, but copper naphthenate poles can be disposed of in sanitary landfills.
Furthermore, there is no indication that disposal of copper naphthenate will be restricted in the future since it has such benign health and safety traits.
Cost and Availability
Copper naphthenate is similar in cost to other oil-borne treatments due to the recent manufacturing economies. The newest copper naphthenate manufacturer is basic in naphthenic acid production so one can predict that the price will be stable with no exaggerated upsets due to transient economic factors. Both southern pine and Douglas fir can be treated with copper naphthenate in plants in the Southeastern and Western United States with a wide range of sizes and classes available.
PG&E Case Study
In a recent interview, Mr. Pete Loechner, retired Senior Standards Engineer of Pacific Gas and Electric, made the following comments on PG&E’s specification of copper naphthenate poles:
“Today’s utilities face challenges from three major groups: the environmental agencies to ‘keep it healthy’; the governmental agencies to ‘keep it safe’; and the utilities and their rate payers to ‘keep it economical.’ These challenges are becoming more severe due to the latest disposal problems for treated wood products.
“But how does the utility standards engineer know which wood preservative to specify? He is familiar with the various physical properties of the soils in his service area. He knows the seasonal climate conditions. Above all, he has knowledge of all approved AWPA preservatives gained by discussing his needs with the preservative treaters and the manufacturers of the preservatives.”
In 1987, Loechner began a new career as PG&E’s Standards Engineer for their wood products. PG&E were purchasing poles treated by suppliers of the three major preservatives. Loechner stated, “On my first day, Supplier X informed me that FIFRA, RCRA and EPA would increase various restrictive regulations that would eliminate preservatives Y & Z. The next day, Supplier Y instructed me that preservatives X & Z would be soon eliminated by the above agencies. One can imagine the panic that occurred for PG&E when Supplier Z related that preservatives X & Y would soon be discarded.
At this time, a fourth preservative for poles was introduced to us: copper naphthenate, a preservative approved by all governmental agencies and listed in the AWPA Standards. Copper naphthenate is also used as a preservative to treat the interior wood of beehives and veterinarians used the preservative to bathe the hooves of animals. Being located in a strict environmentally monitored area, California, PG&E took a thorough look at copper naphthenate.”
PG&E, various pole suppliers, and representatives from the copper naphthenate manufactures performed the following tests:
- Two different types of preservative carriers were tested: oil solvents and liquefied petroleum gas. The oil solvent carrier made the pole surface softer, thus easier for linemen to bore and to climb. The liquefied petroleum gas carrier resulted in a harder wood surface, but allowed some copper naphthenate penetration into the heartwood of the pole.
- As an advocate of through-boring* Douglas fir poles in the ground line area, PG&E substituted copper naphthenate for the then existing preservative. Full penetration of copper naphthenate was obtained from 4 feet below ground line to 4 feet above ground line. Douglas fir poles installed in the field were assayed after a ten year field installation period. Liquid copper naphthenate/solvent solutions were still found in the ground line area.
- Hardness tests, monitoring internal moistures and strength tests using Engineering Data Management’s Pole Test were also conducted.
- Tests were conducted to determine if copper naphthenate migrated into soil away from the pole surface. No migration was found at levels from ground line to 2 feet below ground line.
“The results of these tests prompted PG&E to select copper naphthenate as its major preservative for treating wood poles.”
Mr. Loechner closed by stating, “During my tenure as PG&E’s Senior Standard’s Engineer, I received no complaints from lineman, warehousemen, and/or second and third parties pertaining to copper naphthenate. I believe copper naphthenate poles assist in giving utilities the biggest bang for their buck, a savings that is passed on to the ratepayer.”
Increasingly the utility industry has looked to alternate materials such as concrete, metal or fiberglass poles to address health concerns with treated wood. This re-evaluation of copper naphthenate shows it to be an effective, cost competitive, clean, safe wood preservative that keeps the long-time favorite, the wooden utility pole, preferable to those higher cost alternatives. In short, copper naphthenate is the “customer friendly” preservative for all customers: the public, the purchasers and you, the specifying engineer.
REFERENCES
Note: Copies of the references and other information regarding Copper naphthenate can be obtained at: www.merichem.com.
- Talarek, W. C., “Regulatory Status of Copper Naphthenate Used as a Wood Preservative,” March 31, 2000.
- Amburgey, T.L. and M.H. West. “Field Tests with a Groundline Pole Treatment.” Mississippi State Forest Prod. Lab., Mississippi State, MS. Proceedings of the First International Conference on Wood Poles and Piles. EDM and Colorado State Univ. Press. 1989.
- Barnes, H.M., M.H. Freeman, J.A. Brient and C.N. Kerr, Jr., “Serviceability of Copper Naphthenate-Treated Poles,” International Research Group on Wood Preservation, IRG/WP 00-30214, 2000.
- McIntyre, C. R., “The Performance of Copper Naphthenate,” International Conference on Utility Line Structures, Fort Collins, CO, March 20-22, 2000.
- McIntyre, C.R., “Copper Naphthenate Performance: A New Way to Look at Old Data,” International Research Group on Wood Preservation, IRG/WP 00-30215, 2000.
- Nicholas, D.D. and M.H. Freeman, “Comparative Performance Pentachlorophenol and Copper Naphthenate in a Long Term Field Stake Test,” International Research Group on Wood Preservation, IRG/WP 00-30243, 2000.
- Barnes, H.M. and M.H. Freeman, “Copper Naphthenate-Treated Southern Pine Pole Stubs in Field Exposure: Part I-Gradient and Biodeterioration Analysis 12 Years After Treatment,” International Research Group on Wood Preservation, IRG/WP 00-30242, 2000.
* The Douglas fir species is very popular in the western section of the country. It has the same strength ratings as Southern Pine, but lacks the depth of the sapwood as found in the pine (deeper sapwood gives more penetration of preservative). However, Douglas fir can be through-bored at any level allowing full penetration of a preservative into the heartwood.
