MANAGEMENT OF WASTES FROM WOOD PRESERVING FACILITIES

CHARLES ARTHUR GOVE

P. AARNE VESILIND

Graduate Student and Professor

Department of Civil and Environmental Engineering

Duke University

Durham, North Carolina

INTRODUCTION

Wood preserving is a significant, diverse and well established

industry with five hundred forty-seven known operating plants in

the United States. (1) The principal product of these plants is

chemically treated wood for use as railroad ties, utility poles,

and construction materials. In 1984, the industry treated about

500 million cubic feet of wood products. (2)

Wood is chemically treated to reduce or prevent decay by

microorganisms, attack by insects and to increase its resistance

to fire. Adequate preservation requires the use of large

quantities of toxic chemicals which could cause environmental

damage and may even result in adverse health effects.

Wastewaters from these plants contain not only the normal

sanitary wastes, but unusable and contaminated preservatives

which no longer can be used for the processes. Two other sources

of wastewater are stormwater surface runoff and excess process

water. Solid residues include sludges from wastewater treatment,

insoluble organic materials from waterborne salts, and

contaminated soils from spills or from drippage.

In older plants, the discharge of wastewaters requires

treatment, which has proven to be costly and technically

difficult. As a result, many small plants have chosen to close

their doors instead of invest the money in treatment processes.

This has been because the capital simply has not been available

to them due to their small size and independent operation. These

abandoned plants probably represent serious future clean-up

problems for the regulatory agencies.

The newer facilities, constructed in the past ten years, have

incorporated within their design various pollution prevention

technologies that satisfy environmental regulations and

provide greater efficiency in operation. In reviewing the records

of this industry, it is clear that early recognition of the "zero

discharge" or "total containment" allowed the industry to

modernize and flourish in North Carolina.

The objective of this paper is to review the status of this

industry in North Carolina, to describe the evolution and use of

pollution prevention strategies for wood preservation plants, and

finally to suggest strategies for existing plants for attaining

self containment and zero discharge which will ultimately result

in economic benefit to the plants.

HISTORICAL DEVELOPMENT

The need to protect wood from various forms of decay and

physical weathering has been recognized since ancient times.

Noah was commanded to use pitch while constructing the ark, and

accounts of the use of similar agents are found in other passages

of ancient history. In modern times, different chemicals and

treatments have been tried for wood preservation. Early attempts

include the 1754 patent of John Lewis for the preservation of

wood with bituminous substances (creosote) and 1837 patent of

Margary for treatment in a solution of acetate or sulfate of

copper. (3) Despite these attempts, the actual widespread use of

chemically preserved wood did not begin until the latter part of

the nineteenth century.

The first wood preserving plant in the United States was

placed in operation in 1875 with the construction of a pressure

creosote treating plant in Gautier, Mississippi. (4) The

industry developed rapidly due to the expansion of railroad

systems throughout the country, (1875-1925), and the need for

durable railroad ties. (5) This demand resulted in large-scale

use of creosote treated hardwood products. Further growth was

stimulated after 1925 by the need for treated poles by the

rapidly developing utility companies.

The need for a building material that could survive in marine

environments presented-another use for creosote treated wood.

However the marine borer, Limnoria Tripunctata was able to- -

successfully attack creosote treated marine pilings, and this

prompted further research in the use of other potential chemical

preservatives, resulting in the development of pentachlorophenol

(1930), copper chromium arsenate (1933) and amonical copper

arsenate (1939). (6) With treated wood products successfully

demonstrated, potential uses for treated wood expanded to include

such products as poles, pilings, fence posts, guardrails, bridge

3

structures, boardwalks, and other lumber products. New demands

for treated wood created a need for more versatile products and a

much greater output.

Presently, the wood treating industry uses the following three

chemicals:

. creosote

. pentachlorophenol

. waterborne inorganic arsenicals

While research directed toward developing chemicals and

treating processes is continuing, no new preservatives have been

found to be realistic options for the near term mainly due to

long periods of required testing. Therefore, the industry is

dependent on the preservatives presently in use.

PRESERVATIVE USED FOR TREATING WOOD

Creosote, pentachlorophenol and waterborne inorganic

arsenicals are the major pesticide chemicals used for wood

preservation. Treated wood production in 1984 by preservatives

was: 138 million cubic feet by creosote solutions, 54 million

cubic feet by pentachlorophenol and 301 million cubic feet by

waterborne arsenical preservatives. The major products treated,

which account for 89% of the total production, were lumber and

timber (268 million cubic feet), crossties, switch and bridge

ties (97 million cubic feet) and poles (78 million cubic feet).

(7)

Creosote is produced as a distillate of coal tar and is a

mixture of many compounds, mainly aromatic hydrocarbons. It is

primarily used to improve the weathering characteristics of wood,

provide protection from insects and fungi, and promote

4

insolubility in water. Disadvantages of creosote treated

products are color, oily unpaintable surfaces and tendency to

bleed. The railroad industry uses creosote almost exclusively to

treat cross and switch ties; 99.5% of creosote treated wood

total. (8)

Pentachlorophenol is a crystalline compound dissolved in a

light petroleum oil. Pentachlorophenol treated products are

resistant to insects and fungi and are more paintable than

creosote. 55.5% of all utility poles and greater than 90% of all

utility pole crossarms are treated with pentachlorophenol. (9)

Waterborne preservatives are compounds of arsenic, chromium,

copper zinc, and fluoride. The principal preservative is copper

chromium arsenate (CCA) which differs from creosote and

pentachlorophenol in that it is a water soluble inorganic as

opposed to an oily organic substance. Waterborne preservatives

produce clean, ordorless, paintable products. Disadvantages of

waterborne preservatives are that the wood must be dried before

it is treated rather than using a simultaneous processing step.

(10)

Until the mid-twentieth century, the total volume of wood

preserved corresponded directly to the volume of creosote used.

Since the early 1950's there has been a general decrease in the

consumption of creosote treated products and a corresponding

increase in the use of waterborne and pentachlorophenol

preservatives. Following 1965 there has been an increase in

total wood preserved but a further decrease in creosote

consumption. During the last fifteen years, use of waterborne

5

treated wood for construction has increased approximately

eightfold, while the use of creosote and pentachlorophenol has

decreased about ten percent. (11)

THE WOOD PRESERVATION PROCESSES

Wood preserving is a specialized operation as the specie of

the wood treated, preservative used and type of product influence

ways in which the wood is treated. In addition, environmental

regulations have forced process changes such that there appear to

be no standardization in operations, the process can therefore be

described only in very general terms. Figures 1 and 2 present

block flow diagrams of the wood preserving process for pressure

treatment using oil-based and waterborne preservatives.

Wood preserving is a two stage process; first the wood is

preconditioned to reduce its moisture content, second the wood is

treated with preservatives. The methods used to pretreat or

condition wood depend on the type of wood being treated. In the

United States, most of the wood is preconditioned by ambient air

seasoning, kiln drying, or steaming. Southern pine must be

steamed before it is to be treated with either creosote or

pentachlorophenol. Mixed hardwoods including oak, and woods to

be treated with waterborne preservatives are generally kiln or

air dried and seldom steamed.

Following preconditioning, the wood is impregnated with

preservative by either pressure or non-pressure methods.

Pressure treatments involve the application of pneumatic or

hydrostatic pressure to wood in the presence of chemical

preservatives. Pressure treating accounts for greater than 95%

of all wood treated. Non-pressure processes include thermal,

6

brush, dip, spray, diffusion, vacuum, and soaking methods.

Pressure methods produce deeper penetration of the

preservative. The two pressure techniques used to achieve

greater impregnation are the empty cell and full cell processes.

For woods requiring less penetration of oil-based preservative,

the empty cell process is used. Following conditioning of the

wood, the retort is pressurized causing contraction of air within

the cell walls of the wood. Preservative is then introduced into

the vessel and forced into the voids created in the cell walls.

The full cell process maximizes impregnation of the wood and is

normally employed with waterborne preservatives. In this

process, the pretreated wood in placed in the retort and a vacuum

is imposed causing evacuation of the air trapped within the wood,

next the preservative is entered and pressure is administered to

force the solution into the wood. Generally the vessel is heated

which allows the waterborne preservative to react with the acids

formed from the wood sugars and become "fixed" in the wood. In

both procedures a portion of the preservative solution may drip

from the wood during its removal from the retort. (12)

ENVIRONMENTAL IMPACT OF WOOD PRESERVATION

Concern over the deteriorating quality of the environment has

focused attention on pollution in its various forms and on the

wood preserving industry's contribution to the problem. Since

the chemicals used to treat wood are toxic and wastes from the

treating plants are potentially damaging to the environment,

various agencies have conducted studies on chemical pesticides

used in wood preservation.

Creosote is a broad spectrum wood preservative that has been

used for this purpose for over one hundred years in the United

States. The very fact that creosote has been widely used

commercially as a preservative with little or no evidence of

adverse health effects, suggests that its effects on human health

and the environment might be minimal. However, there are

instances of fish kills associated with contamination of streams

and lakes by creosote and process wastewater from creosoting

operations. (13) Perhaps more important, the Environmental

Protection Agency has identified creosote as a known carcinogen.

(14)

Pentachlorophenol and its salts are widely used biocides in

the United States. The principal use of pentachlorophenol is for

wood preservation, in excess of 80% being used for this purpose

and other activities associated with the forest products

industry. (15) Pentachlorophenol is lethal to a wide variety of

living organisms, both plant and animal. The major issues of

concern are the environmental effects of impurities present in

commercial grade pentachlorophenol and of breakdown products,

10

which are generally classified as chlorinated dioxins and are the

subject of study because of their extreme toxicity. (16)

Copper chromium arsenate is an inorganic arsenical compound

that is a major pesticide chemical now in use for wood

preservation. Although the toxic properties of arsenic have been

known for centuries, the mutagenicity and carcinogenicity of

arsenical toxicity have only received intense investigation in

the past few decades. Studies are underway to determine the

effects of interaction with other toxic metals and physiological

states on the nature of arsenic toxicity. (17)

All preserved wood contains chemicals known to be toxic.

Analyses of solid wastes have been shown to include hazardous

components such as the wood preservatives pentachlorophenol,

creosote and the heavy metal salts. (18) Considerable evidence

also exists which associates direct human contact with these

chemicals to adverse health effects. (19)

THE WOOD PRESERVING INDUSTRY

Wood preserving plants are distributed throughout the united

States, with the majority located in forested regions. Due to

the expense of transportation, wood preservers tend to be located

close to timber cutting operations. In 1984, sixty percent of

all active facilities were located in the South, from east Texas

to Maryland, and greater than thirty-five percent of all new

plants were built in Georgia, North Carolina and Virginia. (20)

The total size and economic characteristics of the wood

preserving industry has been a matter of considerable

uncertainty. In 1977 the Census of Manufacturers identified 457

facilities, however the actual number of plants operating then is

11

estimated at 631 facilities. ( 2 1 ) A recent study, Wood----

Preservation Statistics 1983-84, conducted by the International

Statistics Council has identified 547 active plants in the United

States with 326 operating in the South and thirty located in the

state of North Carolina. ( 2 2 ) A survey of the wood treating

activities in the state of North Carolina conducted as part of

the present study has identified forty facilities in operation

during 1984. Table 1 is a summary of the locations of these

plants in North Carolina.

Although there is disagreement as to the exact size of the

industry, it is acknowledged that the wood preserving industry is

composed principally of a large number of small privately owned

plants and a few large integrated corporations. Most firms in

the industry operate only one plant and specialize in one type of

preservative treatment process. Smaller firms tend to further

specialize on particular preserved wood products. Therefore no

single facility or process can be considered "typical", and such

diversity creates considerable difficulty in pollution control.

Preserved wood is largely a commodity market modified by

transportation costs providing regional advantages. Demand

elasticity in the industry varies among products but the major

factors governing demand are competition within the industry,

economic climate and the cost effectiveness of alternative

products. Since the early 1970's the industry has experienced

significant cost increases for raw materials, especially

chemicals and wood, but has been able to establish higher retail

prices, although with reduced margins. (23)

12

TABLE 1

Location:

Mountain

Piedmont

Coastal

Process

Pressure

Non-pressure

Number of Plants-

10

12

18

35

5

Preservative(l)

Creosote

Pentachlorophenol

Waterborne Inorganic (CCA)

Other

3

9

29

1

[(1) note: Two of the treating facilities employ twotypes of preservatives]

POLLUTION CONTROL IN WOOD PRESERVING PLANTS

The wood preserving industry is currently confronted with the

problem of pollution control to satisfy environmental

regulations. The primary wastes associated with wood

preservation are high volume water streams with various levels of

preservatives. Water pollution is therefore the most serious

problem affecting the industry owing to the extreme toxicity of

the chemical preservatives and the special treatment and disposal

methods required. Recent legislation has discouraged the use of

13

lagoons and evaporation ponds, and thus has resulted in the

development of source control technologies to comply with water

quality standards.

An evaluation of the industry has shown that source control

technologies for pollution abatement can greatly reduce the

expense associated with wastewater treatment. Some of the

methods used by various plants include:

. reduction of the amount of excess toxic chemicals

entering a waste stream

. reductionof the water volume contact with

preservative

. segregation of waste streams

. maximizing separation and recycle of chemicals to the

treating process.

These techniques are applied throughout the wood preserving

process, including chemical handling, wood preconditioning,

environmental contact and operational practices.

The use of toxic chemicals for wood preserving requires

special handling procedures. Currently, the majority of

creosote, pentachlorophenol, and waterborne CCA are sold,

transported and stored in bulk. Bulk shipments are unloaded by

closed systems that pnuematically force the preservative into

storage facilities. However, a small segment of the industry

purchases small quantities which generate container waste. The

use of dedicated recyclable drums with rinseable plastic liners

and unloading with a closed system has been identified as a

source control method that would eliminate container waste and

14

reduce human contact with these substances.

Preconditioning of wood is necessary to reduce its moisture

content and improve its treatability. This is accomplished by

open air drying, kiln drying, or pressure steaming in a retort.

Steaming the wood produces a wastestream composed of water with

preservative, wood fiber, silt, wood sugars, wood acids and oil.

Reduction of steaming by use of air and kiln drying eliminates a

major wastewater stream. In instances where steam conditioning

is necessary or preferred, waste reduction can be accomplished by

decreasing the water volume contact with preservative. Steaming

is necessary for the treatment of southern pine with creosote and

pentachlorophenol, since the wood must be treated while hot to

prevent the formation of sludge on the wood's surface. Converting

from open to closed steaming substantially reduces the volume of

cylinder effluent that must be treated by recycling the steam

condensate separately from the preservative. (24)

In order to increase production and reduce yard inventory when

treating hardwood products, steaming is preferred due to its

greater efficiency over air drying and problem with cracking and

warpage from kiln drying. The use of separate retorts for steam

conditioning and treating physically separates the conditioning

operation from the treatment process. This eliminates the

contamination of the steam condensate waste stream with

preservative.

The most significant pollution problem associated with the

wood treating process is area contamination from storm runoff and

area washdowns. This occurs when excess preservative drips from

the freshly treated charge before it becomes "fixed" in the wood

15

structure and consequential spills that accompany opening the

pressure cylinder door are transported by rainwater runoff and

water used to clean-up drips and spills. Areas under and in the

vicinity of the treating cylinder are the sources of this

contamination. Containment of the excess preservative from a

"freshly pulled" charge is essential to eliminate the unwanted

discharge of chemicals into the environment. Covering the

cylinder entrance and charge preparation area reduces both the

amount of foreign matter and volume of rainwater that would have

to be collected and treated. The installation of spill basins,

drip pads with collection troughs, and sumps beneath the retort

and preparation area allows recycling of the chemical

preservative for further use. At plants using water-borne

chemicals, the recycled preservative is used as makeup water in

preparing new solutions. For facilities using oil-based

preservatives, the wastestream is recycled to an oil/water

separator for recovery of preservative. Collection systems as a

source control technology not only act as pollution control but

soon pay for themselves in recovered preservative. (25)

There are a number of operational practices which are

relatively low cost source control measures that can

significantly reduce and simplify the wastestreams to be

collected and treated. These practices include pretreatment

procedures, p rocess methods, handling of freshly treated wood,

and preventative maintenance.

Prior to the treatment process, the wood should be examined to

assure that it is clean and properly seasoned in order to avoid

16

unnecessary contamination of the preservative solution with wood

acids, sugars, fibers, and other foreign matter. Additionally,

the treating solution should be thoroughly mixed and free from

contamination. Careful stacking of the wood in the retort

assures that after pressure impregnation the excess preservative

can freely drain away from the charge by pumping from the

cylinder. Maximizing the duration and vacuum applied, further

improves the collection of unabsorbed preservative. Freshly

treated charges normally drip preservative for several hours

before chemical fixation occurs in the wood, therefore in order

to contain this "kick back" (drippage) and eliminate area

contamination, it is essential to maximize the amount of time

that the wood is allowed to remain in the evacuated cylinder and

on the drip pad. Before the wood is moved either for storage or

shipment, it should be inspected to insure that the product is

clean and dry.

Leaks in pipes and pumps are another common source of

contamination and represent a loss of usable preservative. The

early detection of leaks through periodic and systematic checking

of plumbing at a treating facility provides pollution control

that reduces operating costs by recovering preservative that

would otherwise be lost. Changes in operational procedures are

practices that should be considered before investing in treatment

systems, since they are significantly less expensive and provide

a better return on investment by recovering valuable raw

materials (preservative).

The storage of spent or contaminated chemicals, or of

contaminated stormwater runoff has traditionally been in unlined

17

lagoons. Such storage is no longer legal, and a question of

lining lagoons with clays to prevent groundwater contamination

has been asked. In order to answer this question, a series of

tests using hydrostatic permeameters with various compacted

clays, simulating clay liners, were conducted. The wood

preserving waste was placed under pressure on these clays and

their permeability measured.

The results show slight increases in permeability, but no

breakthroughs in the tests which lasted for eighteen weeks.

However, a longer test with a waste similar to wood preserving

waste lasted for more than a year and resulted in a catastrophic

breakthrough. The implications are that clay liners could be

considered at best a temporary solution for the storage of wood

preserving wastes.

ENVIRONMENTAL REGULATION

The Environmental Protection Agency under the Resource

Conservation and Recovery Act of 1976 issued a series of

hazardous waste regulations on the wood preserving industry. The

segment of the industry treating with creosote and/or

pentachlorophenol was extensively studied by the agency prior to

the enactment of the legislation. These regulations relating

liability insurance, closure of hazardous waste facilities,

retro-fitting of plants and monitoring of certain hazardous waste

facilities represent major problems to many owners of wood

preserving plants, especially those treating with oil-based

preservatives (creosote, pentachlorophenol).

The wood preserving industry is composed of a large number of

18

small privately owned plants and a few large integrated

corporations. About two-thirds of all plants treating wood are

believed to be "small generators" of hazardous waste and are thus

exempt from most hazardous waste regulations. However, many of

these plants will be subject to costly regulations for management

of hazardous wastes. (26)

In general, the small privately owned treating facilities are

single-plant companies. The projected cost of compliance to

proposed environmental regulations falls disproportionately on

these smaller firms. Proposed liability insurance requirements

apply to each owner rather than each plant, so insurance costs

per volume of output are much greater for the single-plant

company than for the large multi-plant corporation. Obtaining

capital investment funds to renovate existing facilities to

satisfy environmental regulations represent major problem to the

majority of owners of wood preserving plants. (27)

Although the industry is composed of many small firms, the

eight largest companies control about half of the market. (28)

Therefore, a highly competitive market exists among the smaller

producers and the extent to which increased costs stemming from

environmental regulation can be passed on to consumers is greatly

limited by the relatively strong competition among wood treaters.

The proposed liability insurance requirements and providing

financial assurance for future plant closure impose substantial

costs for many wood preserving plants. Furthermore, the rapidly

escalating rates and difficulty in obtaining pollution insurance

places a severe financial hardship on smaller firms.

The segment of the wood preserving industry treating with

19

waterborne inorganic salts does not seem likely to be seriously

affected by the hazardous waste regulations since inorganic

plants are required to be at "zero discharge". Consequently,

recent expansion in the industry has occurred with the

construction of new waterborne inorganic treating facilities and

modification and expansion of existing treating operations to

handle waterborne preservatives.

Although it would appear that converting the segment of the

industry treating with oil-based organic chemicals to inorganic

waterborne preservatives would eliminate waste generation

associated with the wood preserving industry, problems with the

disposal of solid residues still exist. Each of the treatment

processes result in the formation of solid residues including

sludge from the work tank system and wastewater treatment sludge.

Inorganic processes produce less hazardous waste per charge of

wood than oil-based treatments, however the amount of wastewater

treatment sludge by each process is approximately equal. Wastes

generated from oil-based organic preservatives tend to be

biodegradable, whereas wastes from inorganic arsenicals are not.

Presently these solid residues are disposed of at hazardous waste

landfills. Additionally, the markets for oil-based organic and

water-borne inorganic preservatives are sufficiently different

that substitution of chemicals is unlikely.

ECONOMIC IMPACT

Treated wood is primarily used for crossarms, lumber, pilings,

poles, railroad ties, and timber. In most situations, treating

wood increases its life expectancy to five or more times that of

20

untreated wood. (29) Substitute materials such as concrete,

steel or untreated wood, while producing less hazardous waste

than the wood treating process, represent more expensive

alternatives for treated wood products. Therefore, the

elimination of the wood preserving industry would have a major

economic impact in the United States.

Declining supplies and higher prices for naturally resistant

woods, such as cedar and redwood, have resulted in increased

demand for treated softwoods, such as yellow pine. Wood treated

with inorganic arsenicals has provided a suitable substitute for

domestic construction, such as decking. In 1984, 268 million

cubic feet (4,257 million board feet) of treated lumber and

timbers were produced, with 94% treated with waterborne

preservatives. (30) Due to the wide variety of uses for treated

lumber, it is not possible to quantify the economic impact of

non-wood substitute materials, however the likely substitutes of

plastic, steel and concrete all have costs greater than wood.

Qualitatively, the restriction of waterborne inorganic arsenicals

as a chemical preservative would have an adverse economic effect

on the construction business. (31)

Traditionally, the American railroad industry has relied

exclusively on creosote treated wood products for crossties,

switch and bridge ties, and pilings. Concrete is a technically

feasible substitute as railroad ties, however its use is

incompatible with wood ties, requiring the complete replacement

of all wood ties in a given section of track with concrete ties.

This substitution of concrete ties for wood ties represents an

annualized increase in cost of 3.4 billion 1978 dollars for the

21

first year and 2.4 billion 1978 dollars thereafter, a cost that

will most likely be absorbed by the American taxpayer. (32) wood

treated with waterborne inorganic arsenicals are unacceptable

substitutes for creosote treated products due to changes in the

mechanical properties of the material, notably a hardening of the

wood. In 1984, 78 million cubic feet of pressure treated wood

poles were produced. Oil based preservatives provided 85% of

this production, 43 million cubic feet treated with

pentachlorophenol and 23 million cubic feet treated with creosote

solutions. (33) In this application, creosote and

pentachlorophenol are potential substitutes for each other. The

Environmental Protection Agency has projected that the increased

cost for replacement of treated poles with non-wood substitutes

would range from 1.3 billion dollars to 2.1 billion dollars

annually. (34)

Approximately 12 million cubic feet of treated wood pilings

were produced in 1984. Creosote and waterborne preservatives

accounted for greater than 97% of the production, 58% by creosote

and 40% by inorganic arsenicals. (35) In this particular

application, creosote and inorganic arsenicals are not potential

substitutes, owing to the ineffectiveness of creosote treated

pilings in the marine environment and untreatability of certain

wood species with waterborne preservatives. The use of non-wood

substitutes for treated wood pilings, projects an annualized cost

increase by 33% for concrete and 67% for steel. (36)

Economic evaluation of alternative materials for treated wood

products favors the continued use of preserved wood. Although

22

concrete and steel produce less hazardous waste than the wood

treating process, there are increased energy and environmental

costs relating to mining, processing and manufacturing of

substitute materials. Additionally, wood is a renewable domestic

resource whereas the estimated annual need for 29 million tons of

cement, sand, gravel, and crushed stone along with the 1.7

million tons of steel for substitute products holds implications

of a greater dependence on the importation of non-wood raw

materials. (37)

The substitution of oil-based organics with waterborne

inorganic preservatives is a complex issue and in particular

applications they are mutually exclusive. For many uses,

creosote and pentachlorophenol are potential substitutes,

cancellation of either would result in the use of alternatives

rather than in the use of non-wood substitutes. Elimination of

the organic arsenicals would have an adverse economic effect on

the construction industry. Restriction of the use of waterborne

inorganic chemicals and either of the oil-based preservatives

would result in a shift to untreated wood and non-wood

substitutes.

Based on information developed from the 1977 Census of

Manufacturers, an estimated 30,700 people were employed in

treating wood and related timber activities in 1978. During this

period the wood preserving industry employed 13,300 directly in

treating operations, paid 140 million dollars in wages and

consumed 796 million dollars of wood raw materials. An

additional 17,400 jobs in producing, harvesting and processing of

timber were dependent on the wood preserving industry. (38)

23

These benefits accrue to many thousands of citizens directly

and indirectly dependent on the industry in more than 500

communities, most of which are small rural towns in which the

production, processing, and preservation of wood products are

major sources of employment and income. This is especially true

in the state of North Carolina where 95% of the plants are

located in small rural communities. Finding new jobs for workers

displaced by cessation of wood treating operations could entail

substantial transfer costs to many families. Many workers might

not find new jobs because of the lack of opportunities in these

rural areas resulting in at least temporary dependence on

unemployment insurance and welfare.

In 1984 the wood preserving industry provided a market for

more than 500 million cubic feet of standing timber and logs,

much of which came from relatively low-quality trees not suitable

for higher value use, or species for which only a limited market

would exist unless treated. (39) The industry thus promotes sound

forestry management and improved forest environments by utilizing

materials that would otherwise not be marketed and reducing the

demand for higher quality products.

CONCLUSIONS

Wood preserving is a substantial industry in the United States

with extreme significance in the southeastern states that range

from Texas to Maryland. It is composed primarily of small

privately owned facilities that treat wood with toxic chemicals

to produce railroad ties, utility poles, lumber and timber.

Although the wastestreams resulting from the treating processes

24

are damaging to the environment, the industry has achieved a

large reduction in the amount of hazardous waste it produces

through source control technologies. 'In fact most new facilities

have incorporated many of these methods in the design and

construction of new plants.

Although it is possible to construct "zero discharge" plants,

some of the older facilities still produce hazardous waste which

could be a health hazard or pose a threat to the environment,

such as the contamination of groundwater systems with chemicals

that are known carcinogens and suspected mutagens and teratogens.

For older plants, the following specific measures can be

implemented which will result in decreased waste production,

increased retention and use of chemicals and potential savings in

treatment cost:

[l] Installation of drip pads for collecting preservative

during extraction from the treatment cell.

[2] Installation of a roof over the treated lumber, thus

preventing the production of contaminated stormwater

runoff.

[3] Careful inspection of piping and pump seals and

elimination of leaks.

[4] Installation of overflow tanks which would accept

inadvertant overflows from chemical storage tanks.

[5] Installation of recycle systems which would filter out

grit, dirt, and wood fibers from recoverable

preservative.

[6] Installation of oil/water separators at oil-based

organic facilities which would recover reusable excess

25

preservative.

Since many of the source control measures developed by much of

the industry improve operating efficiency in addition to

providing pollution control, implementation will be achieved

through an increase in awareness with more facilities adopting

better operating procedures and replacing older equipment as the

recognition that pollution prevention pays is not merely a

slogan.

Unfortunately, this fragmented industry of small companies in

a highly competitive market has great difficulty in funding

research in source control technologies and obtaining the capital

investment necessary to renovate existing facilities to satisfy

environmental regulations. Therefore in order to assist the

industry and protect the environment it is suggested the

following measures be considered.

[ l ] A program of challenge grants be initiated where the

state governments provide either matching funds or low

interest loans for the construction or purchase of

source control systems.

[2] The funding of additional research into source control

technologies with an emphasis on examining the

methods employed by the petrochemical, metal-plating,

and coal byproducts industries and their potential

application to the wood preserving industry.

[3] Consideration of a state sponsored programthat would

provide liability insurance for facilities that

implement and observe state-of-the-art source control

26

technologies by licensing such plants through a

state agency.

27

[ l ]

[2]

[3]

[4]

[5]

[ 6 ]

[7]

[8]

[9]

[10]

[11]

[12]

[13]

[14]

[15]

[16]

References

Micklewright, James T. Wood Preservation Statistics, 1983 & 1984A Report to the Wood Preserving Industry in the United StatesJanuary 1986 page 2

ibid. page 2

Burt, Henry Potter "On the Nature and Properties of Timberwith Descriptive Particulars of Several Methods, Now in Use,for its Preservation from Decay" January 11, 1853 881 inNo. 881 Institute of Civil Engineers Volume XII Session 1852-3Published by the Institution 1853 London page 215

The Biologic and Economic Assessment Of Pentachlorophenol,Inorqanic Arsenicals, Creosote I: Wood PreservativesEnvironmental Protection Agency technical-bulletin 1658-l

November 1980 Washington, D.C. page 36

Wood Preserving Industry Multimedia Emission InventoryEPA-600/2-81-066 Environmental Protection AgencyApril 1981 Washington, D.C. page 10

ibid. page 10

Micklewright, James T. Wood Preservation Statistics,- -pas- 4

1983 & 1984- -

Wood Preserving Industry Multimedia Emission InventoryEPA-600/2-81-066 page 13

ibid. page 13

ibid. page 13

ibid. page 14

Gurfinkel, German Wood Engineering Southern Forest- -Products Association 1973 New Orleans, Louisiana page 124

The Biological and Economic Assessment Of Pentachlorophenol,Inorganic Arsenicals, Creosote Volume I: Wood Preservatives

Technical Bulletin 1658-1- -

page x x v 1 1

Wood Preserving Industry Multimedia Emission InventoryProject Summary EPA-600/S2-81-066 Environmental ProtectionAgency September 1981 Washington, D.C. page 3

Rao, K. Rango Pentachlorophenol; Chemistry, Pharmacologyand Environmental Toxicology Plenum Press 1978 New York page 3

ibid. page 13

[17]

[18]

[19]

[20]

[21]

[22]

[23]

[24]

[25]

[26]

[27]

[28]

[29]

[30]

[31]

[32]

Fowler, Bruce A. Biological and Environmental Effects ofArsenic Elsevier 1983 New York page 277

Wood Preserving Industry Multimedia Emission Inventor- -EPA-600/2-81-066 Environmental Protection Agency- April 198

Washington, D.C. page 18

Wood Preserving Industry Multimedia Emission Inventory- - - - - - - - - - - - -Project Summary EPA-600/S2-81-066 page 3

Micklewright, James T. Wood Preservation Statistics, 1983 & 1984- - -Appendix II

Josephson, H. R. Economic Impacts of Hazardous Waste Regulationson the Wood Preserving Industry Prepared for the American- -Wood Preservers Institute October 1981 page 7

Micklewright, James T. Wood Preservation Statistics 1983 & 1984- -table 2

Economic Impact Analysis of Alternative Pollution ControlTechnologies Wood Preserving Subcategory of the Timber ProductsIndustry EPA-440/2-79-018 U.S. Environmental Protection Agency,Office of Water Planning and Standards September 1979

Washington, D.C. page 29

Thompson, Warren S. "Pollution Control" in Wood Deteriorationand Its Prevention by Preservative Treatments; Volume II.Preservatives and Preservative Systems Darrel D. ----Nicholas editorSyracuse University Press 1973 Syracuse, New York page 366

ibid. page 370

Josephson, H.R. Economic Impacts of Hazardous Waste Regulationson the Wood Preserving Industry page 7- - -

Economic Impact Analysis of Alternative Pollution ControlTechnologies EPA -44-/2-79-018 page 11

ibid. page 21

Micklewright, James T. Wood Preservation Statistics,page 2

1983 & 1984- - -

ibid. page 2

Wood Preservative Pesticides: Creosote, Pentachlorophenoland the Inorganic Arsenicals Position Document 2/3EPA-540/9-82-004 Environmental Protection Agency March 1982

Washington, D.C. page 30

ibid. page 28

[33] Micklewright, James T. Wood Preservative Statistics, 1983 & 1984- _ -page 2

[34] Wood Preservative Pesticides: Creosote, Pentachlorophenoland the Inorganic Arsenicals EPA-540/9-82-004 page 32- -

[35] Micklewright, James T. Woodtable 1

Preservative Statistics, 1983 & 1984- _ -

[36] Wood Preservative Pesticides: Creosote, Pentachlorophenoland the Inorganic Arsenicals. Position Document 4EPA/540/9-84/003 Environmental Protection Agency July 1984

Washington, D.C. page 36

[37] The Biologic and Economic Assessment OfInorganic Arsenicals, Creosote Volumetechnical bulletin 1658-1 page xxvii

[38] ibid. page xxii

PentachlorophenolI: Wood Preservatives- -

[39] Micklewright, James T. Wood Preservation Statistics, 1983 & 1984- - - - - - - -page 2

APPENDIX:

Hydraulic Conductivity of Clay Soils

Exposed to Wood Preserving Wastes

The wood preserving industry utilizes hazardous chemicals in

the treatment of wood. The treating process therefore generates

hazardous waste, represented by the preservative that is not

impregnated into the wood. This excess preservative is collected

for recycling and stored in steel tanks, concrete lined pits or

clay lined lagoons.

Abandoned lagoons containing wood preservative wastes have

recently been targeted for "Superfund" cleanup operations.

Therefore, the importance of investigating the effects of wood

wastes on clay soils has just recently been recognized. Hence, a

series of experiments were conducted to determine the hydraulic

conductivity of clay soils permeated with wood preserving wastes.

The state of North Carolina has 40 wood preserving plants,

of which 29 use waterborne preservatives. This significant use

of inorganic chemicals and the possible incompatibility of the

test equipment with organic substances, such as the oil-based

preservatives, led to the selection of a waterborne preservative

as the test specimen. The particular material tested is a

chromated copper arsenate, type C (CCA-C), obtained from a

confidential location in eastern North Carolina.

The wood preserving waste tested contains ions of CU, Zn,

Cr, and As in various concentrations with an extremely low pH of

approximately 2. Research has shown that clays flocculate if

they are percolated with bi- or multivalent rich solutions,

resulting in a slight increase in hydraulic conductivity. Also,

the effect of an extremely low pH on the clay could lead to a

gradual breakdown of the clay lattice resulting in a dilute

amorphous silica gel. The solubility of such a gel is fairly

high, so the hydraulic conductivity could be expected to increase

with time.

The effect of inorganic waste on clay liners was tested

using hydrostatic fixed-wall permeameter cells. (Figure A-1)

These different clays were tested and the waste was placed on top

of the compacted clays at a pressure of 14 psi for eighteen

weeks. (Details of the test procedure are found elsewhere. [A-l])

Results from these tests showed a gradual increase in

hydraulic conductivity after the application of the waterborne

inorganic waste. The increase in hydraulic conductivity for the

different clays were approximately:

. 0.4E-7 cm/s - White Stone Clay

. 0.5E-7 cm/s - Faceville Clay

. 0.1E-7 cm/s - Hoytville Clay

These results agreed with the previous results for other types of

wastes. [A-2]

Because of a lack of time and equipment, the wood preserving

waste cells were run for only eighteen weeks. One experiment,

using a high ionic strength and low pH waste which could be

expected to react in a similiar way to wood preserving waste, was

continued for over a year until it broke through the clay. The

breakthrough, and the obvious change in the physical character of

the clay, suggests that clay liners in lagoons holding wood

preserving wastes are at best temporary storage solutions.

Although it is not possible to draw any definite conclusions

from the tests performed within the scope of this research, a

gradual increase in hydraulic conductivity could be expected

during prolonged testing of a flexible-wall cell with clay

permeated with inorganic wood preservation waste, and the

breakthrough with a similiar waste indicates potential clay liner

destruction with prolonged exposure. The implications of this

conclusion suggest that clay lined lagoons are at best short term

solutions for the storage of hazardous wastes generated by wood

treating facilities.

References: Appendix

[A-1] J. Jeffrey Peirce Hydraulic Conductivity of Clay- -Soils Exposed to Inorganic Waste Liquids Generated bySeveral Industries U.S. Environmental ProtectionAgency, Contract No. 68-03-3149, 24-4 pgs. 76-88

[A-2] ibid. pg. 94

Bibliography

Biologic and Economic Assesment of Pentachlorophenol,Inorganic Arsenicals, Creosote Volume I: Wood PreservativesEnvironmental Protection Agency technical bulletin 1658-1November 1980 Washington, D.C.

Burt, Henry Potter "On the Nature and Properties ofTimber, with descriptive particulars of several methods, nowin for its Preservation from Decay" January 11, 1853in Institution of Civil Engineers, Volume XII,Session 1852-53 1853 London

'Economic Impact Analysis of Alternate Pollution ControlTechnologies Wood Preserving Subcategories of the TimberProducts Industry EPA-440/2-79-018 U.S. EnvironmentalProtection Agency, Office of Water Planning and StandardsSeptember 1979 Washington, D.C.

Fowler, Bruce A. Biological and Environmental Effects ofArsenic Elsevier 1983 N e w Y o r k - - -

Goldstein, Irving S. editor, Wood Technology: Chemical- -Aspects ACS Symposium Series 43 American Chemical SocietyWashington, D.C. 1977

Gurfinkel, German Wood Engineering Southern ForestProducts Association 1973 New Orleans, Louisiana

Josephson, H.R. Economic Impacts of Hazardous Waste- - - -Regulations on the Wood Preserving Industry

- -Prepared for- -

the American Wood Preservers Institute October 1981

Micklewright, James T. Wood Preservation Statistics, 1983-84A Report to the Wood Preserving Industry In the UnitedStates January 1986

Nemerow, Nelson L. Industrial Water PollutionAddison-Wesley Publishing Company 1978Reading, Massachusetts

Nicholas, Darrel D. editor, Wood Deterioration and Its- - Prevention by Preservative Treatments; Volume I: Degradationand Protection of Wood, Volume II: Preservatives andPreservative Systems Syracuse University Press 1973-----Syracuse, New York

Overcash, Michael R. editor Decomposition of Toxic and NontoxicOrganic Compounds in Soils Ann Arbor Science Publishers- -1981 Ann Arbor, Michigan

Rao, K. Ranga Pentachlorophenol; Chemistry, Pharmacology,and Environmental Toxicology Plenum Press 1978 New York

Wood Preserving Industry Multimedia Emission InventoryEPA-600/2-81-066 Environmental Protection AgencyApril 1981 Washington, D.C.

Wood Preserving Industry Multimedia Emmission InventoryProject Summary EPA-600/S2-81-066 Environmental ProtectionAgency September 1981 Washington, D.C.

Wood Preservative Pesticides: Creosote, Pentachlorophenol- -and the Inorganic Arsenicals Position Document 2/3- -EPA-540/9-82-004 Environmental Protection AgencyMarch 1982 Washington, D.C.

Wood Preservative Pesticides: Creosote, Pentachlorophenoland the Inorganic Arsenicals Position Document 4EPA/540/9-84 Environmental Protection AgencyJuly 1984 Washingon, D.C.