Soil Leaching from Copper Naphthenate-Treated Utility Poles

Transcription

1 Soil Leaching from Copper Naphthenate-Treated Utility Poles James A. Brient Naphthenic Acid Technology Manager Merichem Co. Houston, TX Presented at the International Conference on Utility Line Structures March 2002 Fort Collins, CO Abstract Leaching of wood preservatives into the soil surrounding wooden structures is an area of concern to utilities as well as to informed consumers and the treated wood industry. States have established residential soil cleanup standards for sites contaminated with hazardous substances, including heavy metals and organic contaminants introduced into soil from treated wood. Copper naphthenate is an effective preservative for utility poles, posts, piles, and other wooden structures that contains no arsenic, chromium or chlorinated dioxins/dibenzofurans. Copper naphthenate-treated utility poles installed in 1987 in the Puget Sound, WA area were monitored for copper migration and depletion over a four-year period after initial installation, and soil samples were also assayed for copper leaching. This paper reports on a follow-up study on those poles and soil near the poles for copper content after 14 years of service, and expands the original study to include soil assays for organic constituents. Soil samples from more recently installed poles (1993) and background soil samples from both sites were also measured for copper and organics content. Introduction Copper naphthenate is a proven effective wood preservative for protection against decay fungi and wood-destroying insects. 1-4 Standards were established within the American Wood-Preservers' Association (AWPA) for specific commodities for wood treated with copper naphthenate in the mid- 1980s 5, and major commercial uses include utility poles (both pressure treatment and remedial treatment), fence posts and piles. Copper naphthenate is diluted in organic solvents such as diesel fuel or mineral spirits to facilitate penetration into the interior of the wood. Recommended AWPA minimum retention levels for coastal Douglas fir poles treated with copper naphthenate include 0.075, 0.095, and pounds per cubic foot (pcf, as Cu metal), depending on the deterioration zone and local natural sub-environment. The Puget Sound area of Washington is in the AWPA Deterioration Zone 4 (high potential for deterioration). Harp and Grove 6 studied the retention of copper in poles and leaching of copper into soil from copper naphthenate-treated coastal Douglas fir poles at five utilities across the country. Poles installed in the Puget Sound area in 1987 originally had an average copper naphthenate retention of pcf (as Cu). Pole cores were taken at the groundline and near the brand ~5 feet above groundline over 4 years to monitor copper migration within the pole. Retention data from the study (Figure 1) indicated copper depletion from the outermost core assay zone over four years but no significant downward migration toward the groundline ("GL" in Figure 1). The lack of any consistent migration of copper into deeper

2 (interior) assay zones suggests possible radial migration of copper out into the surrounding soil. Analyses of soil samples taken within 4 inches of the poles confirmed migration of copper into the soil, with average soil copper content increasing from 80 ppm to 800 ppm after 4 years. This 1993 study did not address any associated migration of diluent oil/carrier (#2 diesel) into soil surrounding the poles. A follow-up study to the 1993 Harp and Grove study was recently done to reevaluate soil around these copper naphthenate treated poles. Specifically, the previous study was expanded to include analyses of soil for total petroleum hydrocarbons (TPH) and other regulated hydrocarbon contaminants such as polynuclear aromatic hydrocarbons (PAH). Soil samples and pole core samples were again taken for copper assay. Pole cores and soil samples were also collected at a second site in the Puget Sound area where copper naphthenate-treated poles were put in service in An environmental auditing firm supervised sample collection, and contract analytical labs performed all sample analyses. Figure 1. Copper migration within poles between (data from Ref. 6) Although all soil samples were assayed for copper, cost considerations precluded a comprehensive survey of organic constituents in all samples. Soil from selected poles at Site #1 were fully analyzed for TPH, volatile petroleum hydrocarbons (VPH) and PAH. Unfortunately, information came to light after the study was completed showing that creosote treated poles had been in service at site #1 since the 1930's, and were replaced with the existing copper naphthenate poles in The potential for soil contamination from the previously installed creosote poles adds an element of uncertainty to the results of soil from that site, particularly on TPH and PAH results. Background EPRI 7,8 conducted a similar project on soil leaching from utility poles treated with pentachlorophenol (PCP) and creosote. Samples collected at several distances and depths proximate to 202 in-service utility poles (180 PCP and 22 creosote) in 28 states were analyzed for several physical and chemical parameters, including ph, total organic carbon, TPH, chlorinated phenols, and PAH. The data revealed a

3 rapid decline of PCP concentrations with increasing distance (up to 4 feet) from the wood pole. TPH concentrations exhibited a trend similar to PCP in that attenuation of TPH occurred rapidly with increasing distance from the pole. Maximum TPH values ranged over three orders of magnitude, ranging from <60 to >50,000 mg/kg, with an average of 5000 mg/kg. Total PAH concentrations in soil near creosote poles decreased by as much as five orders of magnitude over the same distance, with an overall average attenuation of two orders of magnitude. Overall, migration was highly dependent on localized factors such as soil type, soil chemistry, local weather and topography, initial level of pole treatment, age of pole, and other factors. Laboratory studies on leaching of copper naphthenate in various solvents from treated southern pine wafers showed an increasing tendency to leach with increasing boiling point range of the solvent. 18 No differences in Cu leaching rates were seen between copper naphthenate in mineral spirits and waterborne chromated copper arsenic (CCA), and copper leaching into soil was greater than into water. Hein 19 showed that copper naphthenate was essentially immobile and non-leachable by water after application to the top of a column of soil. Non-detectable levels of copper were found in neutral water leachate over a one-year leaching study. Buchanan 20 found that copper naphthenate treated utility poles exposed to simulated acid rain leached measurable amounts of copper to the environment, but the copper was immobile and remained largely fixed in the soil. The Model Toxic Control Act (MTCA) is a Washington State extension of the federal Superfund Act that established procedures to clean up sites contaminated with hazardous substances, including total petroleum hydrocarbons. Washington State promulgated maximum water and soil levels for various chemicals, including wood preservatives and components of their diluent oils. Action levels requiring cleanup based on the amended MTCA Method A include 2000 mg/kg for TPH in soil, including dieselrange organics. 9 Copper is included in the cleanup levels and risk calculations (CLARC) under MTCA riskbased Method B (unrestricted/residential land uses) and Method C (industrial/commercial land uses). The soil cleanup levels based on direct ingestion of copper are 2960 mg/kg and 130,000 mg/kg for Methods B and C, respectively. 10 Petroleum distillate fractions such as diesel or #2 fuel oil are predominantly composed of alkanes, cycloalkanes (naphthenes), and monocyclic aromatic compounds. The small quantities of PAH present in #2 diesel are typically lower molecular weight species by virtue of their lower boiling points, mostly 2- ring compounds such as naphthalenes. 11 Creosote is a higher boiling coal tar fraction that contains significantly higher levels of 3-, 4- and 5-ring PAH isomers (Table I). The carcinogenic PAH isomers of concern are 4- and 5-ring compounds such as benzo[a]pyrene and chrysene. Testing for carcinogenic PAH content is not required for #2 diesel because data exist to indicate their absence. 12 PAH accumulate in sediments or soils where they are degraded by microbial metabolism and photodegradation. Microbes in the presence of oxygen degrade lower molecular weight compounds more quickly, and higher molecular weight compounds degrade more slowly, particularly in anaerobic environments. Literature data shown in Figure 2 indicate all of the 2- and 3-ring PAH isomers present in creosote-contaminated soil are diminished by biodegradation or photodegradation. Likewise, all of the more refractory 4- and 5-ring PAH components in soil increase in relative abundance compared to the original creosote treating solution. PAH such as those found in creosote are very hydrophobic and bind tightly to organic matter such as soil. In upland environments it appears that PAH remain within cm (6-12 inches) of the pressure treated wood structure. 13

4 Table I. Typical PAH Content in Creosote and Petroleum Fuel Oil (from Ref. 11) Major PAH Isomers # of Rings Creosote Range, % Average, % #2 Fuel Oil, % 1-Methylnaphthalene Methylnaphthalene Biphenyl Dimethylnaphthalenes Naphthalene Acenapthene Anthracene Carbazole Dibenzofuran Fluorene Methylanthracenes Methylfluorenes Methylphenanthrenes Phenanthrene Benzo[a]anthracene Benzofluorenes Chrysene Fluoranthene Pyrene Benzo[a]pyrene Dibenz[a,h]anthracene Figure 2. PAH isomers in creosote and creosote-contaminated soil (Ref. 11)

5 Methods and Materials Borings were taken from 14 coastal Douglas fir poles, including 10 treated by Pacific Wood Treating and installed in 1987 (site #1, poles PB-PL), and 4 treated by Nevada Wood Preserving or Koppers and installed in (site #2, poles WM1-WM4). Two borings were taken from each pole, at the groundline and near the brand (~5 feet above groundline). Cores were taken near plugged holes from previous borings. All poles were visually inspected and sounded to detect signs of decay or insect attack. Cores from poles at each site were measured individually for Cu penetration but were composited for Cu retention assay. The borings were segmented into outer and inner assay zones and ground using a Wiley Mill and dried in a forced-draft oven at 100 C for 6 hours. The wood samples were analyzed for copper retention by Timber Products Inspection (Conyers, GA) using atomic absorption spectroscopy (AAS) according to American Wood-Preservers' Association Standard A The ground wood samples were divided in half to make replicate samples. Soil samples were collected near all poles using a stainless steel trowel since soil hardness, rocky backfill and proximity to the pole precluded using a soil auger. Soil samples from both sites were taken at radial distances of 4 inches and 12 inches from the pole. Additional soil samples were taken 10 feet from poles at the two sites for background copper and total petroleum hydrocarbon assays. Soil samples were collected and segmented into samples representing 0-3 inches depth and 3-6 inches depth. Equipment was cleaned with Alconox detergent and deionized water between each sampling to avoid sample contamination. Soil assays were performed by North Creek Analytical, Inc. (Bothell, WA). All soil samples were analyzed for dry weight and copper content by inductively coupled plasma-atomic emission spectroscopy (ICP- AES) following EPA Method 6010B. Selected soil samples were analyzed for total petroleum hydrocarbons by extraction with methylene chloride followed by GC analysis to qualify and quantify components. 14 TPH components were classified as "diesel" and "lube oil" range hydrocarbons. Samples were also analyzed for volatile petroleum hydrocarbons 15, and extractable petroleum hydrocarbons 16. Selected samples were analyzed by GC/MS for polynuclear aromatic hydrocarbons (PAH) and several specific chemicals since Washington State mandates soil cleanup levels for those compounds. The chromatographic methods give a quantitative and qualitative analysis of the hydrocarbons present in the soil sample. Benzene/ethylbenzene/toluene/xylenes (BETX), MTBE and naphthalene were analyzed using EPA Method 8260B. Results and Discussion Brands on the poles did not include any information on the target Cu retention during treatment. AWPA Standard C4 for poles provides guidelines rather than specific instructions as to which retention to use in a particular deterioration zone. Minimum retention targets of or pcf Cu would be acceptable for AWPA Deterioration Zone 4, including the Puget Sound area. Copper retention in copper naphthenate-treated poles remains at or above minimum recommended retentions after 14 years in service, as shown in Table II. Poles installed at site #1 in 1987 (poles PB-PL) had an average retention of 0.10 pcf Cu in the standard AWPA C4 assay zone 0.25" to 1.0" from the surface. Analyses of core samples from these poles by Harp & Grove 6 found an average of pcf Cu at time of installation and pcf Cu after 4 years of service.

6 Table II. Copper Assay of Pole Cores Retention, pcf Cu Site 1 Pole Core # Class/Length Year Treated Treater Std zone Inner zone Penetration, in. PB 1 2/ PWP PC 2 2/ PWP PD 3 2/ PWP PE 4 2/ PWP PF 5 2/ PWP PG 6 2/ PWP PH 7 2/ PWP PJ 8 2/ PWP PK 9 2/ PWP PL 10 2/ PWP Site 1 WM1 11 2/ PWP WM2 12 2/ Koppers WM3 13 1/ Koppers WM4 14 1/ Koppers The more recently installed poles from site #2 averaged 0.18 pcf Cu after 8 years in service. This is 20% above the highest recommended target retention for copper naphthenate treated coastal Douglas fir poles, suggesting the poles were significantly overtreated when originally installed. Excellent penetration of preservative into the poles is confirmed by the Cu retention in the inner assay zone 2.0" to 2.5" from the surface. No signs of decay or insect attack were observed in any of the poles surveyed. The current study shows a continuing migration of copper into soil surrounding the poles. Soil assays summarized in Table III show highly variable Cu concentrations from pole to pole. Soil collected 4 inches from the poles installed at site #2 averaged 220 mg/kg Cu after 8 years in service. This represents a minor increase over background levels. In spite of the apparent overtreatment of these poles with copper naphthenate, this average copper level is an order of magnitude below the 2960 mg/kg Washington State MTCA cleanup level (Method B) for direct ingestion from soil from unrestricted/residential land uses. 8 Minimal differences were seen in Cu content regardless of distance from the pole or depth of sample. The current study did not determine copper naphthenate leaching from soil into groundwater, which is anticipated to be negligible based on its high octanol/water partition coefficient (K ow 12,000). The MTCA pre-calculated value for copper in groundwater that would be protective of human life (not the groundwater cleanup level) is 592 µg/l for Method B. Cu content in soil samples from poles installed at site #1 in 1987 was highest near the poles, and only slightly less at 3-6 inches deep than at 0-3 inches the surface. The average Cu levels in surface samples taken 4" from poles at site #1 had increased from 718 mg/kg after 4 years of service 6 to 1124 mg/kg after 14 years. Surface samples taken 12" from the poles increased on average from 133 mg/kg to 511 mg/kg. Similar increases were seen in soil samples taken at 3-6" depth. These copper levels are still

7 below the cleanup level for direct ingestion from soil. Increased migration of copper into soil from this site may have been influenced by the presence of previous creosote poles. Table III. Summary of Soil Copper Content (mg Cu/kg, dry basis, by ICP) Distance from pole 4 inches 12 inches Sample Depth 0 to 3 inches 3 to 6 inches 0 to 3 inches 3 to 6 inches Site 1 PB PC PD PE PF PG PH PJ PK PL Site 1 Average Background Site 2 WM WM WM WM Site 2 Average Background Headspace analyses taken in the field immediately upon soil sample collection showed no detectable volatile organic content. Laboratory analyses confirmed this observation, with total volatile petroleum hydrocarbons all but non-detectable (<10 mg/kg) in selected soil samples from Site #1 (Table IV). Only C 12 -C 13 aromatics, the heaviest analytes in the extractable petroleum hydrocarbons method, were detected at all. Aromatic hydrocarbons including benzene, ethylbenzene, toluene, xylenes and naphthalene were also non-detectable in the soil samples tested. Total petroleum hydrocarbons in soil were detected in significant but highly variable quantities by semivolatile hydrocarbon analyses (Table V). TPH averaging 500 mg/kg at site #2 indicates a minimal leaching rate when copper naphthenate poles are the only potential source of TPH. This is below the 2000 mg/kg MTCA unrestricted land use (residential) Method A soil cleanup level for diesel-range TPH. Individual samples from site #1 ranged from <500 to 49,000 mg/kg, averaging 20,000 mg/kg where the soil was potentially contaminated after 50+ years of exposure to creosote-treated poles. These levels are similar to those found near pentachlorophenol treated poles in the EPRI study. 9

8 Table IV. Assay of Individual Petroleum Hydrocarbon Types in Soil (mg/kg dry basis) Site 1 PG-4x0/3 PG-4x3/6 PH-4x0/3 PL-4x0/3 Total Volatile Petroleum Hydrocarbons C 5 -C 6 Aliphatics ND* ND ND ND C 6 -C 8 Aliphatics ND ND ND ND C 8 -C 10 Aliphatics ND ND ND ND C 10 -C 12 Aliphatics ND ND ND ND C 8 -C 10 Aromatics ND ND ND ND C 10 -C 12 Aromatics ND ND ND ND C 12 -C 13 Aromatics MTBE** ND ND ND ND Benzene ND ND ND ND Toluene ND ND ND ND Ethylbenzene ND ND ND ND m,p-xylenes ND ND ND ND o-xylene ND ND ND ND Naphthalene ND ND ND ND Total Extractable Petroleum Hydrocarbons C 8 -C 10 Aliphatics ND ND ND ND C 10 -C 12 Aliphatics ND ND ND ND C 12 -C 16 Aliphatics C 16 -C 21 Aliphatics C 21 -C 34 Aliphatics Total C 8 -C 34 Aliphatic Hydrocarbons C 10 -C 12 Aromatics ND ND ND ND C 12 -C 16 Aromatics C 16 -C 21 Aromatics C 21 -C 34 Aromatics Total C 10 -C 34 Aromatic Hydrocarbons * ND = not detected ** MTBE = methyl t-butyl ether Diesel-range hydrocarbons were much more prevalent than lube oil-range hydrocarbons at site #1, but were seen at comparable levels in soil from site #2 (Table VI). The predominant extractable petroleum hydrocarbons in the soil were C 16 -C 21 aliphatic and aromatic compounds (Table IV). Total petroleum hydrocarbons were 40-fold higher at site #1 than at site #2. Since site #1 soil may have been contaminated from the old creosote poles, the data from site #2 are more reflective of actual TPH leaching from copper naphthenate treated poles. Background soil samples were not analyzed for hydrocarbons.

9 Table V. Total Petroleum Hydrocarbons in Soil (mg/kg, dry basis) Site 1 Distance from Pole 4 inches 12 inches Sample Depth 0 to 3 inches 3 to 6 inches 0 to 3 inches PB 46,800 41, PC 35, PD 479 PE 32,550 PF 2898 PG 48,950 26, PH 20, PJ 427 PK 583 PL 11, Site 1 Average 20,067 15, WM WM WM-3 91 WM Site 2 Average 509 Site 2 Table VI. Total Petroleum Hydrocarbon Distribution in Soil * (mg/kg, dry basis) Site 1 Sample 1 Diesel Lube Oil PB 43, PC 33, PD PE 30, PF PG 44, PH 19, PJ PK PL Site 1 Average 18, Site 2 WM WM WM WM Site 2 Average *TPH from samples collected at 4 out and 0-3 depth.

10 Soil samples collected at site #1 (poles PB-PL installed in 1987) also contained elevated PAH levels, as shown in Table VII. Total PAH concentrations in four soil samples ranged from mg/kg, with individual isomers ranging from non-detectable to 23 mg/kg. Normalized values for PAH isomers in Table VIII indicate that the predominant isomers detected in the soil were the heavier 4- and 5-ringed compounds such as pyrene, fluoranthene, benzo[b]fluoranthene, and benzo[a]anthracene. In only one instance was a 3-ring PAH observed in the soil. PAH containing 3 rings or less were either not present initially or were biodegraded or volatile enough to diminish over time in soil. Table VII. Soil Analyses for Polynuclear Aromatic hydrocarbons (mg/kg, dry basis) PAH Isomer PG-4-0/3 PG-4-3/6 PH-4-0/3 PL-4-0/3 Acenaphthene ND ND ND ND Acenaphthylene ND 0.1 ND ND Anthracene ND ND ND ND Benzo[a]anthracene* Benzo[a]pyrene* Benzo[b]fluoranthene* Benzo[ghi]perylene Benzo[k]fluoranthene* Chrysene* dibenz[a,h]anthracene* Fluoranthene Fluorene ND ND ND ND Indeno[1,2,3-cd]pyrene* Methylnapthalene ND ND ND ND Naphthalene ND ND ND ND Phenanthrene ND ND ND ND Pyrene Total PAH Total carcinogenic PAH Benzo[a]pyrene equivalent * Classified by Washington State as a carcinogenic PAH (Ref. 12) Literature values in Table VIII show that PAH isomers containing 4 rings are significant components of creosote and creosote-contaminated soil but are present at minimal levels in #2 fuel oil. The PAH detected in soil samples collected during this study are not consistent with those present in #2 diesel, but rather appear to have originated from creosote. Follow-up conversations with the utility confirmed that the poles installed at site #1, where soil contained elevated TPH and PAH, were indeed replacements for creosote-treated poles.

11 Component Table VIII. Relative Abundance of Polycyclic Aromatic Hydrocarbons in Solutions and Soil * # of Rings Diesel 2 Creosot e ** Soil Creosot e 2 2-Methylnaphthalene Naphthalene Acenaphthene Acenaphthylene 3 no data Anthracene Fluorene Phenanthrene Benzo[a]anthracene Chrysene Fluoranthene Pyrene Benzo[a]pyrene Benzo[b]fluoranthene 5 no data Benzo[k]fluoranthene 5 no data dibenz[a,h]anthracene Indeno[1,2,3-cd] pyrene 5 no data Benzo[ghi]perylene 6 no data * Normalized PAH concentration in solutions or soil samples, % of total PAH ** Typical values (Ref. 11) PG- 4-0 PG- 4-3 PH- 4-0 PL- 4-0 Conclusions The copper naphthenate-treated poles in the Puget Sound, WA continue to retain copper at levels at or above the minimum recommended retention for that AWPA Deterioration Zone after 8-14 years in service. No sign of decay or insect attack was observed in any of the poles. Copper levels in soil 4 inches from the poles averaged 220 and 1124 mg/kg at the two sites studied. These concentrations are less than half the 2960 mg/kg cleanup level for copper calculated from the Washington State Cleanup Levels and Risk Calculations (CLARC) Method B based on direct ingestion of soil from unrestricted (residential) land uses. TPH levels in soil collected from site #2, where the copper naphthenate poles were the original installation, averaged an order of magnitude below the Method A cleanup level of 2000 mg/kg listed for diesel range organics. TPH in soil collected near ten poles at site #1 averaged above the MTCA Method A residential cleanup level, but this site previously held poles treated with creosote. Volatile petroleum hydrocarbons (VPH) were non-detectable in soil collected at site #1, the only site where soil samples were assayed for VPH. Polynuclear aromatic hydrocarbons (PAH) were not assayed in soil samples from site #2. High PAH levels in soil near the copper naphthenate poles in service for 14 years at site #1 may have been influenced by creosote-treated poles in service for over 50 years prior to installation of the copper naphthenate poles.

12 The predominant PAH isomers identified in the soil were consistent with residual creosote, although a full site assessment was not conducted and other potential sources of PAH contamination were not investigated. References 1. Minich, A.; Goll, M The technical aspects of copper naphthenate as a wood preserving chemical. Proc., American Wood-Preservers' Assoc. 44: Asmus, R. W.; Kelso, W. C., Jr.; Hein, R. W Copper naphthenate: A proven wood preservative. Proceedings of The Eighth Wood Pole Institute, Colorado State University, Ft. Collins, CO. pp Gjovik, L. R.; Gutzmer, D. I Comparison of Wood Preservatives in Stake Tests (1985 Progress Report). USDA Forest Service, Forest Products Laboratory, Research Note FPL-02, Madison, WI, 100 pp. 4. Freeman, M.H. 1992b. Copper Naphthenate: An effective wood pole and crossarm preservative. In: Proceedings, First Southeastern Pole Conference (H.M. Barnes, T.L. Amburgey, eds.), Mississippi State University, Starkville, MS, Proceedings 7314, Forest Products Society, Madison, WI, pp American Wood-Preservers' Assoc Annual Book of Standards. American Wood- Preservers' Association, Granbury, TX. 6. Harp, K.L. and Grove, S.L Evaluation of Wood and Soil Samples from Copper Naphthenate Treated Poles in Service. Proc., American Wood Preservers' Association. Vol. 89, pp Anon., Interim Report on the Fate of Wood Preservatives in Soils Adjacent to In-Service Utility Poles in the United States EPRI Report TR Anon., Pole Preservatives in Soils Adjacent to In-Service Utility Poles in the United States. EPRI Report TR Washington State Department of Ecology, Model Toxics Control Act - Cleanup Regulation, Chapter WAC, amended February 12, Washington State Department of Ecology, Cleanup Levels and Risk Calculations Under the Model Toxics Control Act Cleanup Regulation (CLARC). Publication , Version 3.1, updated November Petrusca, M. and Labiosa, J. E Best Demonstrated Available Technology (BDAT) Background Document for Wood Preserving Wastes F032, F034 and F Washington State WAC , Table footnote Brooks, K.M Literature Review, Computer Model and Assessment of the Potential Environmental Risks Associated With Creosote Treated Wood Products in Aquatic Environments. In: Goyette and Brooks (1999). Creosote Evaluation: Phase II, Sooke Basin Study - Baseline to 535 Days Post Construction Environment Canada, Pacific and Yukon Region, 224 Esplanade, North Vancouver, British Columbia, Canada V7M 3H pp. 14. NWTPH-Dx method for semi-volatile petroleum hydrocarbons (extended), in "Analytical Methods for Total Petroleum Hydrocarbons", Washington Department of Ecology Publication No., ECY , June Washington State Department of Ecology, Analytical Methods for Total Petroleum Hydrocarbons - VPH Method. Publication No. ECY June, Washington State Department of Ecology, Analytical Methods for Total Petroleum Hydrocarbons - EPH Method. Publication No. ECY June, 1997.

13 17. Washington State Department of Ecology Toxics Cleanup Program Interim Interpretive and Policy Statement - Cleanup of Total Petroleum Hydrocarbons. Ecology Publication No. ECY Table McAfferty, E.J Soil Leaching of Wood Preservatives. Mooney Chemical Co., Lab memo 3506-M. 19. Hein, R.W Mobility of Copper Naphthenate in Soil. Mooney Chemical Co., Lab memo 3601-M. 20. Buchanan, R.D Persistence, Leaching and Availability of Chromated Copper Arsenate- Polyethylene Glycol, Copper Naphthenate and Pentachlorophenol Wood Preservatives from Pressure Treated Utility Poles. Master's Thesis, University of Guelph.