Data Package to Support the Re-Affirmation Of AWPA CCA-Type C [Chromated Copper Arsenate] In AWPA Standards P-5 and P-23

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Data Package to Support the Re-Affirmation Of AWPA CCA-Type C [Chromated Copper Arsenate] In AWPA Standards P-5 and P-23 Mike H. Freeman Independent Wood Scientist/Chemist July 01, 2013 Executive Summary
Data Package to Support the Re-Affirmation Of AWPA CCA-Type C [Chromated Copper Arsenate] In AWPA Standards P-5 and P-23 Mike H. Freeman Independent Wood Scientist/Chemist July 01, 2013 Executive Summary At the Spring 2013 AWPA Technical Committee meetings in Honolulu, Hawaii it was mentioned, under Agenda Item 12(Outline work for ensuring year), that the AWPA Standard for CCA-Type C would be up for Re-Affirmation in No Task Force was formed at that time. The attached Data Package details the requirements for AWPA Preservative Re-Affirmation of CCA-Type C and includes papers published on CCA since the last Re-Affirmation in 2008 and supporting documents for it s Re-Affirmation. With no negative performance issues known to have been observed on this Preservative in the last 5 years since it s last Re-Affirmation, it is recommended that AWPA Preservative listed in Standards P-5 and P-23 be Re-Affirmed as written. Review Existing Standard The Standard for CCA-C in the AWPA BoS has historically been listed as Standard P5 section 6. In 2007, Freeman and Jung re-formatted the wood preservatives into the new Preservative Standard format and issued it for publication to Colin McCown, as AWPA Executive Vice President, which included a DRAFT watermark until final review and reaffirmation. This P23 Standard has been reviewed and is in need of no editorial changes and corrections. Earlier the team of Shields and Fox submitted changes and those corrections to Colin McCown following the AWPA Spring 2010 Annual meeting. These corrections have now been made; including the removal of the Draft watermark on P-23 and it is now fully listed as AWPA Standard P-23, after following the removal of the DRAFT watermark. AWPA Standard P-5.6 is also adequate, but needs to also incorporate changes and it reads satisfactory as well, but it is the understanding of this author, this Standard would soon be retired and archived under the AWPA System, much like the Use Category System replaced the Commodity Standards. The author suggests both standards be re-affirmed until all P-5 Standardized wood preservatives are archived. Efficacy Data and Reports A Complete Efficacy Review is attached to this Data Package and covers over 5 decades of efficacy and evaluation testing of CCA. Additionally, under APPENDIX 1, to this Data Package, are the following Documents: Freeman, et al, This study is report on the 53-year exposure of Boliden Salts Type B treated wood pole stubs in southern Mississippi (AWPA Hazard Zone 5). This report and study indicates that wood treated to 0.7 PCF CCA-Type B Salts (as Oxides) has an estimated service life in AWPA Hazard Zone 5 of 73 years in 6-8 inch diameter Southern Pine Pole Stubs. It should be noted that this retention is slightly above the current AWPA recommendation for wood utility poles in this hazard zone, being roughly only 16% above that of the required assay for Southern Pine in Hazard Zone 5, and 68% of the pole stubs/posts are still performing well. Woodward, Hatfield, and Lebow, USDA-FPL-02 (Extracts). In this USDA Study, CCA-Type C when tested in 2x4 SYP 100% sapwood stakes, in AWPA Hazard Zones 3, 4 and 5, tested an evaluated at retentions ranging from 0.14 pcf CCA to 0.79 pcf CCA, stakes treated to 0.14 pcf performed well for 29 years (23% of AWPA Retention for CCA utility poles) and when tested at 0.60 pcf CCA (100% of AWPA CCA Pole Retention), no failures where observed after 40 years. Woodward, Kirker and Lebow, In the AWPA Task Force Report on CCA posts installed in AWPA Hazard Zone 5, no CCA posts have decayed after 35 years of exposure, including those posts installed at 0.40 pcf CCA (as Oxides), or 67% of the AWPA CCA pole retention. Lebow, In this paper USDA-Forest Products Technologist Stan Lebow reviews the efficacy trials of both CCA and ACA. This study indicates that CCA retentions, based even on early data sets, have most likely been set at the correct long-term performance retentions in the AWPA Standards. Product Performance There have been no widespread failures of CCA-Type C treated wood products in service, over the last 30 + years, other than those minor occurrences of a few single bad poles failing to either treater error or drying prior to treatment issues; additionally, no performance problems have been observed since 2008, since the last CCA Re- Affirmation. MSDS s and US EPA Product Labels Currently, only three basic manufacturers are registered by the US EPA to sell and market CCA-Type C into the USA for pressure treating. These three companies, Lonza (formerly Arch Chemicals), Osmose, and Viance maintain US EPA Restricted Use Pesticide labels with the US EPA. CCA has just recently undertaken and completed the extensive seven-year Re-Registration program with the US EPA and Industry and the RED has been issued. Example US EPA labels and Product MSDS s are attached under APPENDIX 2. Extension of Exposure Conditions CCA maintains use patterns for utility poles, piling and other specific uses as outlined by the US EPA RED and a Settlement Agreement from the producers and the US EPA as mandated and agreed upon in February 2002, and promulgated fully on December 31, CCA has complete data package and support for use in areas on the USA for FST conditions, and currently maintains no use limitations, other than residential lumber uses. Additional New Data Conductivity of CCA Treated Wood There has been periodic discussion within groups of electrical engineers and utility linemen over the conductivity of CCA treated wood poles over the last decade. Apparently, having the name copper in the treatment designation seems to give rise to show concern to certain parties. In 1992, Freeman published findings on Southern Pine. Over the last year, two additional studies have been performed on CCA treated wood, comparing it to the conductivity of small clears (Ragon et al 2010), pole stubs, (Ragon at al These findings were first published at the South East Wood Pole Conference in Memphis, TN, and at the recent AWPA Annual meeting. One of these AWPA papers is attached under APPENDIX 3. In summary, they indicate the testing of CCA treated SYP pole stock was only slightly more conductive than untreated SYP pole stock and only slightly more conductive than comparative oil-borne treatments. The study also illustrates the significance of wood MC on the conductivity testing of all types of treated wood. Gaff Penetration Shupe, Wu and Freeman, Over the years, there have been many rumored complaints about the ability to climb CCA poles. In this complex, and detailed study of three gaff types, including the one designed by former Koppers employee, Harry Demers, especially for CCA poles, it was determined, that CCA poles were no harder to climb or have gaff penetration than pole stock of either untreated Southern Pine or Penta treated Southern Pine. This study is attached under APPENDIX 4. Carey, In this 20 years update on CCA/Oil system from Koppers/Arch/Lonza, trial results from actual climbing tests on CCA treated poles indicate the ease of climbability can still be observed after multiple years exterior field exposure. This study is attached under APPENDIX 5. Summary and Closing Remarks Currently in the USA, three chemical companies supply CCA for pressure treating wood. Today, there are 158 domestic and 27 Canadian treaters treating with Chromated Copper Arsenate (CCA-C). These treaters are producing mainly utility poles, piling (land and fresh water, foundation and marine), structural timbers, fence posts, plywood and a very small amount of crossties. In the US market, roughly 165 million poles are in service, with roughly 35 % of them being previously pressure treated with CCA. The CCA volume domestically in the USA, is approximately 40 million oxide pounds and over 70 million cubic feet have been produced in N. America on an annual basis for the last 4-5 years, with a growing percentage of both the pole and the marine piling market. Based on these facts and the long positive efficacy history of CCA-Type C, this preservative should be re-affirmed in the AWPA BoS. CCA EFFICACY: A Comprehensive and Critical Overview of Existing Data Mike H. Freeman INDEPENDENT WOOD SCIENTIST Memphis, TN Factors Affecting CCA Efficacy CCA preservatives have served well in many applications throughout the world. For several years CCA was undisputedly among the most effective wood protecting chemical against a wide spectrum of wood degrading organisms under challenging terrestrial and semi-aquatic (wet) environments. However due to the potential environmental hazards of heavy metals, several regions with long established CCA markets (North America, Japan, Europe and Australasia, Indonesia, Japan, South Korea) decidedly restricted the usage of CCA preservative to non-residential environments and mandated the use of more organic alternatives (Wong and Lai 2007). Evaluation of CCA alternatives commenced in the early 1990s for health, safety and environmental grounds. Studies evaluating replacements of CCA always compare it as the benchmark. In response to concerns on arsenic and chromium, a number of copper-based inorganic and organic systems have been developed and standardized as alternatives to CCA. Older arsenic free formulations such as CCB and AZCA coexisted with CCA. The newer alternatives all rely heavily on copper as their primary biocide but include inorganic or organic co-biocides. These include alkaline copper preservatives with copper solubilized as an aqueous amine or ammoniacal complex, in combination with cobiocides to provide protection against copper tolerant fungi and termites. They include alkaline copper quaternary (ACQ), acid copper chromate (ACC), copper HDO and copper azole (Lebow et al. 2004). CCA is widely regarded as one of the most effective preservatives for ground contact use. Main factors affecting CCA performance are formulation type, test site and test specimen size, retention of CCA, formulation type and treatment method. This section will elaborate on factors that affect CCA efficacy and compare CCA efficacy with that of the newer alternatives now on the market. Effect of treatment method and Retention level on CCA Efficacy Although the full cell (Bethell) process is routinely used for CCA, Lowry and Rueping (empty cell) or modifications of them are also employed. A number of studies have considered the effects of CCA preservative application method on the efficacy (Hedley et al. 1990; Preston and Mckaig 1983, Hedley et al. 1995b); Hedley et al. 1996; Peek and Willeitner 1988). All these studies show a marked difference between preservative microdistribution between the Bethell and Lowry processes. It is assumed that similar copper retentions ought to give equal control of decay irrespective of treatment process. However this was not the case in a study by Hedley et al. (1990) in which they examined effects of treatment processes on Pinus radiata sapwood (40x40x500 mm³) treated with a range of concentrations of the CCA (Tanalith C) using Rueping, Lowry or Bethell processes. Treating pressure, treatment time and final vacuum was the same for all treatments. Final vacuum was 15 min for Bethel and 45 mins for Lowry and vacuum. Initial vacuum was -85kPA for Bethel and initial pressure for the Rueping process was 350 kpa for 5 minutes. Samples were then reduced to 40x40x7 mm³ test blocks and exposed to Coniophora puteana a copper tolerant brown rot species by agar block. Replicate blocks were analysed for preservative components. Results showed significant differences in efficacy of CCA when applied by the different processes (Table 2). The order of effectiveness was Bethell Lowry Rueping. While weight loss caused by decay to 10% required 0.028% copper for Bethell, it required 0.072% Cu for Lowry treatment and % Cu for Rueping process (Hedley et al.1990). Similarly weight loss against just copper retention (column 3) showed significant difference between the treatments. This difference was explained by differences in distribution of preservative elements following treatment by the three processes especially at low retentions. Preservative solution fills cell lumen voids at completion of the Bethell process and as the solvent dries more active ingredients are deposited on the lumen wall than would be the case for empty cell treatments in which much less preservative is left in the cell lumen after treatment. Even at low treating solution concentrations this deposit from the Bethell process is richer in toxic ingredients than that which is left from the empty cell processes with higher solution concentrations. Lumen deposits are more important against brown rots like the pure culture fungus used in this study. Table 2. Efficacy of CCA when applied by different treatment processes Treatments Analyzed Retentions % weight loss in wood samples % TAE % Cu % Cr % As Bethell Lowry Rueping Relative proportions of preservative elements in the Bethell treated blocks were close to those expected from relative proportions in the formulations. However in the Lowry and Rueping treated blocks, disproportionation of elements was evident at lower retentions. In a second study, Hedley et al. (1995a) compared the three treatment methods (same parameters as in Hedley et al. 1990) on Pinus radiata sapwood but on fungus cellar stakelets exposed in unsterile soil beds in the FRI Fungus Cellar. Results after 65 months exposure indicate that performance was related only to preservative retention. Differences in treatment process had little effect on decay resistance. This is in contrast to results from pure culture decay tests, reported by Hedley et al. (1990) who indicated that disproportionation of preservative elements using empty cell processes had significant effect on durability. Wood treated by full cell would have greater deposits of CCA on cell wall lumina (2-5 times higher as shown by electron microscope) than material treated with empty cell process and is important in decay protection (Chou et al 1973). This study shows that while this may be true for basidiomycete attack it does not necessarily apply to soft rot decay. Lumen deposits of CCA are not necessary to inhibit penetration of soft rot into the S2 layer and is unlikely to inhibit tunneling bacteria. Unlike pure culture decay tests, on the basis of fungus cellar tests, preservative efficacy is related only to preservative retention and dosage response for all three treatments could be represented by a single curve. Furthermore this results were confirmed in a third study in which Hedley et al (1995b) evaluated effect of treatment method on CCA performance using Radiata pine field stakes installed in a a graveyard (loam soils and annual rainfall of 1509 mm). Stakes were inspected at yearly intervals using AWPA M- 10 standard procedure. After 5 years statistical analysis showed no difference between treating processes and performance was related solely to retention expressed either as copper retention or total element (Cu+Cr+As) retention. To study the influence of application method on preservative efficacy Newman and Murphy (1992) treated Corsican pine (Pinus nigra) samples with CCA formulation using Bethel, Steam/Bethel or Lowry processes. After leaching, sets of replicate mini-blocks were exposed to the brown rot Coniophora puteana FPRL 11E, white rot Coriolus versicolor FPRL 28A, and soft rot Chaetomium globosum FPRL S70K. Equivalent sets of leached blocks, were analysed for preservative elements. Steaming predisposed the wood to fungal decay and reduced efficacy. Significant differences in performance of CCA against brown, white or soft rot decay fungi were found depending upon the preservative application method. Differences in preservative microdistribution between lumen surfaces and the S2 layer account for the effect of treatment method on variation of CCA efficacy against brown, white and soft rot. When exposed to the brown rot, wood treated by the three processes performed in the order Bethell Steam/Bethell Lowry and in the order Bethell Lowry Steam/Bethell when exposed to white rot. In the control of brown rot, the balance and overall level of preservative active elements is of more importance than the preservative distribution at cellular level. When attempting to control decay by white rot, once a threshold level of CCA concentration within the wood has been reached, preservative distribution at tissue levels is of paramount importance. Newman and Murphy (1993) presents further data testing of CCA treated Corsican pine by serial exposure in and unsterile soil to Coniophora puteana and Coriolus versicolor. In serial exposures, blocks are re-exposed to fresh cultures with weight loss determination leaching and resterilization between exposures. After 3 exposures Bethell treated material performed consistently better than the Lowry treated when wood was exposed to Coniophora puteana. After 3 exposures to Coriolus versicolor treated wood performed in the order Lowry Bethel Steam/ Bethell. Lowry treated material performed consistently better than the Bethell. Brown rot fungi will tend to be less susceptible to the effect of CCA components distributed within the cell wall than those deposited on the lumen surfaces (Newman and Murphy 1993). In contrast with brown rot, white rot decay is localized around the hyphae and all cell wall polymers are degraded. Therefore an even distribution of preservative across the thickness of cell wall will have a constant reducing effect on the progress of white rots. Such distribution is promoted by the Lowry process where a much greater amount of the applied CCA is in the cell wall whereas in the Bethell, process a significant portion of the CCA remains in the cell lumen. (Newman and Murphy 1993). CCA applied by Lowry treatments is also considerably more effective in preventing soft rot than an equivalent retention applied by the Bethell process. For softrots, which occurs as cavity formation in the S2 layer, a more even preservative distribution across the cellwall i.e a Lowry distribution would be more effective than a Bethell pattern. The microdistribution data indicate a strong correletion between S2 layer Cu and white rot and soft rot control. After a Bethell process large amounts of CCA precipitate in the cell lumen and only a relatively small proportion is distributed in the fiber S2 layer making the timber susceptible to soft rots (Newman and Murphy1993, 1996; Daniel and Nilsson 1989). Pre-treatment steaming caused a general reduction in preservative efficacy through inherent change in wood substrate as opposed to major changes in CCA micro distribution or fixation. This reduced performance may arise from increased decay susceptibility of the wood substrate, chemical and physical changes in the wood which affect CCA fixation, at treatment of the wood at 60% MC affecting the fixation and or distribution of CCA. The chemical nature of hemicellulose, cellulose and lignin s is affected by steaming (Newman and Murphy 1996). Manipulation of treatment method offers potential to enhance the spectrum of activity of CCA against parts of the decay hazard. Effect of Formulation type on CCA efficacy. AWPA Type B formulations (e.g., Boliden K33) do not perform as well in NZ as type C formulations (Tanalith C) (Hedley et al. 2000). However one long term study reported by Ralph (1984) showed otherwise. In this study, between 1951 and 1963, Aspen poplar fence posts full cell pressure treated with CCA-A, CCA-B and CCA-C (Tanalith C) were installed in Ontario Canada in a park site with on sandy loam soil with mm annual rainfall. Visual examination, microscopic examination, splinter tests, and a physical test (30-Ib) horizontal force applied at breast height were used to rate the poles on a scale of 1-6 with 1 being sound and 6 having failed in service when subjected to the physical test. Table 2 outlines results of g
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