Comparison of Environmental Emissions from ACQ (Type B) and CCA Wood-Treating Operations' Abraham S. C. Chen Principal Research Scientist Battelle Columbus Operations 505 King Avenue Columbus, Ohio 43287 and Paul Randall Chemical Engineer U.S. Environmental Protection Agency Pollution Prevention Research Branch Risk Reduction Engineering Laboratory 26 W. Martin Luther King Drive Cincinnati, Ohio 45268 This study was funded wholly or in part by the U.S. Environmental Protection Agency (U.S. EPA) under Contract No. 68-CO-0003 to Battelle. Funding of this study does not signify that the contents necessarily reflect the views and policies of the U.S. EPA or Battelle; nor does mention of trade names or commercial products and processes constitute endorsement or recommendation for use. Representatives of Chemical Specialties, Inc. (CSI) are acknowledged for identifying and locating a wood-treating plant for this technology evaluation and for providing support during the course of this study. The wood-treating plant also is acknowledged for providing support during the on-site evaluation.
Transcript
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FDEF I Waste Management Poilution Prevention Program Library NO. XYCC-ek
Comparison of Environmental Emissions from ACQ (Type B) and
CCA Wood-Treating Operations'
Abraham S. C. Chen Principal Research Scientist
Battelle Columbus Operations 505 King Avenue
Columbus, Ohio 43287
and
Paul Randall Chemical Engineer
U.S. Environmental Protection Agency Pollution Prevention Research Branch Risk Reduction Engineering Laboratory
26 W. Martin Luther King Drive Cincinnati, Ohio 45268
This study was funded wholly or in part by the U.S. Environmental Protection Agency (U.S. EPA) under Contract No. 68-CO-0003 to Battelle. Funding of this study does not signify that the contents necessarily reflect the views and policies of the U.S. EPA or Battelle; nor does mention of trade names or commercial products and processes constitute endorsement or recommendation for use.
Representatives of Chemical Specialties, Inc. (CSI) are acknowledged for identifying and locating a wood-treating plant for this technology evaluation and for providing support during the course of this study. The wood-treating plant also is acknowledged for providing support during the on-site evaluation.
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ABSTRACT
This study compared environmental emissions from a wood-treating plant using
ammoniacal copper/quaternary ammonium compound, Type B formulation (ACQ-B) as an
alternative wood preservative to chromated copper arsenate (CCA). The most obvious
r 7 change in environmental emissions is the complete elimination of arsenic and chromium,
which eliminates the generation of Resource Conservation and Recovery Act (RCRA) wastes
and the risk of contaminating the environment with these RCRA metals. ACQ-B, however,
produces a greater amount of air emissions, mainly as NH,.
INTRODUCTION
Chromated copper arsenate (CCA) is the most predominant wood-treating preserv-
ative used in the United States (2,4,36). CCA is highly effective in protecting wood from
biological deterioration and is resistant to leaching (13,17,18,31), presumably due to
formation of low-solubility reaction products in the treated wood. The use of CCA,
however, has drawn much attention because of the adverse effects of arsenic (As)
(28,30,37) and hexavalent chromium (Cr[VII) (28). The primary concerns are exposures of
humans to both wood-treating operations and treated wood, and contamination of the envi-
ronment by emissions, inadvertent spills (251, and brirning of the treated wood.
Increasingly stringent federal and local regulations have been proposed and enacted
(14,351. For &le, in 1990, the U.S. Environmental Protection Agency (EPA)
established three new categories of hazardous waste that affected wood treatment plants
using arsenic and chromium (35). The new RCRA regulations established standards for drip
pads for treatment plants using various preservative chemicals ( 1 4).
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Alternative preservatives have been sought to reduce As and Cr(V1) use. Ideal alter-
native preservatives must be safe to use, effective in protecting wood, slow to dissipate
from treated wood, and cost-effective (6). The relatively new wood preservative system,
ACQ, exhibits some of these qualities. Patented in Canada (1 5,161, ACQ contains ammo-
niacal copper and a quaternary ammonium compound (quat) (1 ). The combined biocidal
! effect of the active ingredients - copper and quat - protects wood from biodeterioration
under a variety of geologic and climatic conditions (3,19,21,22,24), but exhibits relatively
low mammalian toxicity (3). It is not known, however, if workers are exposed to an
unacceptably high level of ammonia during treatment operations, especially when unloading
the treated wood from the pressure cylinder.
Treated wood stored in open yards can be leached by stormwater. Using an
accelerated laboratory test (1 1, Jin and Preston (23) reported up to 14% loss for copper,
3% for quat, and 19% for ammonia. Most investigations of leachability have used acceler-
ated laboratory experiments (1,12,13,17,18,32); very few have used large-scale leaching
models. In 1979, Chen and Walters subjected CCA-treated southern yellow pine GYP) ply-
wood to artificial rainfall using a rain tower facility and examined the arsenic content in
runoff, leachate, and soils ( 1 1). In 1992, Archer and co-workers field-tested ACQ's leach-
ability (3). A practical setting must be used to examine ACQ's leachability, especially to
estimate the loss of active ingredients under field conditions.
Pressure treatmeqt with ACQ is similar to that with CCA. Because ammonia in ACQ
corrodes brass, bronze, copper, and aluminum, the valves, fittings, and other parts in con-
tact with ACQ m'ust be replaced with parts made of mild steel, stainless steel, fiberglass,
and other nonmetallic materials. The treatment plant must have adequate ventilation to
vent ammonia in the work areas and a covered drip pad to protect freshly treated wood
from rain for at least 6 to 8 days after treatment (including 2 to 3 days wrapped in plastic
to avoid formation of blue deposits on the wood surface and 4 to 5 days of ammonia dissi-
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pation after removal of wraps). ACQ currently is sold as two separate components, i.e.,
ammoniacal copper and quat. The current cost of the ACQ components is 2.7 times more
expensive than that of CCA. The economics of converting from CCA to ACQ will be
reported elsewhere.
This study assessed the use of ACQ Type B formulation (ACQ-B) as an alternative to
,, CCA in a commercial wood-treating plant and compared environmental emissions from both
treating operations. Previous studies had compared the long-term effectiveness of ACQ
relative to CCA (3,21,22,23).
EVALUATION APPROACH AND EXPERIMENTAL METHODS
Evaluation Site
The evaluation took place in a wood-treating plant in central Ohio that fabricates
tree-length wood into commodities and specialty products. The facility had been using
about 300,000 Ib of CCA oxide per year to treat about 15 million board fcst of
commodities. In July 1993, the facility began using ACQ to treat some wood. The three
parallel treating cylinders in the treatment building (Nos. 9 an3 10 in Figure 1, both 6 f t x
40 ft; and No. 8, 6 ft x 66 ft) sit on concrete and/or steel supports in a 9-ft-deep, heated
and insulated basement (shaded area in Figure 1) surrounded by concrete wllls. Each CCA
treating cylinder (No. 8 or No. 9) is on line with a combo tank and a work tank, which are
linked to CCA co.ncentrate tank No. 7 and process tank No. 3. The No. 10 cylinder,
retrofitted for ACQ treatment, intakes ACQ working solution from work tank No. 16
through combo tank No. 13, which is connected to ammoniacal copper concentrate tank
No. 24 and the quat concentrate tote No. 25. Table 1 shows the dimensions and volumes
of these tanks. All cylinders and tanks are made of steel, except for the ammoniacal copper
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concentrate tank and the quat concentrate tote which are made of fiber glass and plastic,
respectively.
Vacuum exhaust and pressure relief during CCA treatment vent to the CCA work
tanks. The CCA work tanks and concentrate tank vent to the CCA process tank, which
vents to the atmosphere inside the building. During ACQ treatment, the vacuum exhaust,
pressure relief, ACQ work tank, and ACQ concentrate tank all vent through a 6-in polyvinyl
chloride (PVC) pipe to the outside.
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The 220 ft x 85 ft drip pad building (see Figure 1) contains door pits for the CCA
and ACQ treating cylinders, tracks leading from the door pits to load and unload wood
units, and drip pads. The concrete floor slopes latitudinally in two 1 1 O-ft segments away
from the middle of the building to avoid accumulation of chemical solution and washdown
water on the drip pads. CCA- or ACQ-containing water drains through the respective door
pit (divided by a steel divider to prevent solutions from mixing), or a floor sump (No. 421,
and is reused as a diluent in the respective combo tank. The concrete floor also slopes
longitudinally toward each of the three tracks used to pull treated wood from the cylinders.
Eleven and six tram cars are used for the 66- and 40-ft cylinders, respectively. One
dedicated forklift is used to move wood on the drip pads. U.S. Department of Transporta-
tion (DOT) hazardous waste drums (No. 41 l are used to store the annual generation of
approximately 75 to 100 Ib of hazardous waste materials before disposal.
The insuiated drip pad building, open at one end, is not heated. Doors on the sides
enable tank trucks to unload chemicals through leak-ptoof quick couplers. The drip pad
building has botHa hood vent and a ceiling vent to allay the sharp ammonia odor of
ammoniacal copper.
Wood products are air-dried in the storage yard for 3 months or steam-dried and kept
in the storage yard for 10 days prior to treatment. CCA pressure treating starts with
vacuuming at 27 in Hg for 20 to 25 min, flooding the retort in 10 to 12 min, pressure treating
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a t 150 to 160 psi for 25 to 30 min, blowing back CCA solution to the work tank in 10 min,
and final vacuuming at 23 in Hg for 15 min. The ACQ process is essentially the same except
that, after pressure treatment, a slow pressure release first vents the cylinder pressure from
150 to 20 psi in 5 min, followed by air venting the cylinder pressure to atmospheric pressure
in 1 min.
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Experimental Methods
Because ACQ-B does not contain As and Cr(VI1, its use can result in a substantial
reduction in toxic waste and prevention of pollution. However, it is important to identify
any toxic emissions resulting from ACQ-B use. Sources of pollution monitored during CCA
and ACQ-B treatment included emissions to ambient air of NH, and Cu during ACQ-B t reat-
ment and As, Cr(VI), and Cu during CCA treatment; drips and spills during all operations (no
experiments performed); solid wastes accumulated on the drip pads (little had accumulated
on the drip pads after either treatment); and stormwater runoff in the open storage yard.
ACQ-5 and CCA Treatment: ACQ-8 and CCA working solutions were prepared according to
manufacturer specifications (Tables 2 and 3). Three charges of SYP lumber, timber, and
fence posts were treated in the respective ACQ-B or CCA pressure cylinder. Tables 4 and 5
show the chemical uptake, total active ingredients absorbed, and calculated (or analyzed)
retention by each treatment charge. The calculated CCA retentions wsre close to the
treatment targets-of 0.4 and 0.6 Ibift3, and the calculated ACQ-B retentions were about 10
to 30% lower than the analyzed values according to AWPA Standard M2-91 (1 1. The dis-
crepancy was attributed to underestimation of the heartwood volume (or overestimation of
the sapwood volume; only sapwood absorbed and retained preservative chemicals). The
ACQ-B solution for charge A 7 was not analyzed; the wood borings sampled from that
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charge contained 0.85 Ib/ft3 active ingredient, about twice as much as the target retention
(0.4 Ib/ft3). A t least 19 out of 20 wood borings sampled met the penetration requirements
specified by AWPA Standard C2-92 (1 1, indicating adequate treatment.
Air Emissions and Worker Exposure Monitoring: Air monitoring approximated full-shift (8-hr)
I' and short-term ( 1 5-min) occupational exposures. SKC Model 224PCXR3 or Gillian HFS-113
sampling pumps placed in the worker's breathing zone (2-ft-radius sphere around a worker's
head per OSHA) or in stationary locations (Table 6 and Figure 1) operated for a full shift or
15 min. Exposures were calculated as the time-weighted average (TWA) of the full-shift
and 15-min samples. Personal exposures of the yard boss to As and Cu and the outside
loader operator to Cr(V1) and NH, provided information on background (outdoor)
concentrations.
It was sunny and breezy during CCA treatment. Temperatures ranged from 64 to
77OF and relative humidities (RHs) ranged from 66% (treatment building) to 80% (drip
pads). It was sunny and cool during ACQ-B treatment. Temperatures ranged from 56 to
62OF and RHs ranged from 60% (treatment building) to 88% (drip pads). The treatment
plant operator spent the entire workshift in the treatment building. The drip pad ground
man and drip pad loader operator spent approximately 25% of their workday in the drip pad
building loading and unloading wood. At all other times they were outside, typically loading
and unloPding trucks in the lumber yard.
A semiquantitative detecting device, the Drager tube (ammonia 2/a, 5/a, and 0.5%/a
manufactured by' National Drager, Inc. [Pittsburgh, PA]), was used to obtain a rough
estimate of ammonia concentrations at various monitoring locations throughout the ACQ-B
pressure treatment process, at different levels above ground, and a t various distances from
the surface of the treated wood on the drip pad.
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Leaching of Treated Wood: After 4 days on the drip pad, two 36 in x 42 in x 8 ft treated
wood units from each treatment, each consisting of 42 rough-cut timber pieces of 6 in x
6 in x 8 ft, and one control, underwent a leaching study. The wood units were stacked
crosswise on top of three or four similar units approximately 4 ft apart (Figure 21, with a
sheet of heavy-duty polyethylene liner placed under each top unit. The separating liners
were arranged to collect runoff directly under each top unit. A garden sprinkler about 6 ft
above the floor and 9 ft from the test units produced artificial rainfall, which was measured
by five rain gauges placed on top of the top units and a t locations covering the entire test
area. The runoff collected within the liner boundary flowed to a 32-gal plastic container.
A t intervals, the volume of runoff collected in each plastic container was measured and
composite or grab samples were analyzed for the analytes listed in Table 6. A tap water
sample was analyzed as a field blank.
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RESULTS AND DISCUSSION
Air Emissions and Worker Exposures
Table 7 presents air quality monitoring results as either full-shift or short-term
concentrations and, where appropriate, as a TWA of the full-shift and short-term samples.
For concentrations below airborne quantitation limits, a value equal to half the airborne
quantitation limit was used in the TWA calculation. Field blank and outdoor monitoring
results were reported as less than the analytical limits of quantitation.
Air Emissions during ACQ-B Treatment: Ammonia short-term concentrations ranged from
5.4 to 38 ppm. The short-term exposure of 38 ppm in the drip pad ground man's breathing
zone when unloading and stacking ACQ-B-treated wood exceeded the exposure limit of
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35 ppm STEL recommended by OSHA, NIOSH, and ACGIH (Table 8). All other short-term
concentrations were below 35 ppm. The 8-hour, TWA concentrations ranged from 0.45 to
8.4 ppm, less than 35% of the NIOSH REL and ACGIH TLV-TWA of 25 ppm. The drip pad
loader operator and the drip pad ground man wore full-face air-purifying respirators (APR)
when the ACQ-B cylinder door was opened and during wood unloading.
:! The DrBger tube measurement results are presented in Table 9. During chemical
mixing, ammonia in the areas surrounding all chemical tanks and totes was below the
detection limit; 32 to 200 ppm were detected at the vent during addition of ammoniacal
copper, quat, and water to the combo tank; and 0.17% to 0.26% was detected during
solution transfer from the combo tank to the work tank. During pressure treatment,
concentrations in the vacuum pump assembly area (No. 23) ranged from 1.5 to 41 ppm;
two of 18 measurements exceeded the STEL. Concentrations of 2 to 5 ppm were detected
about 10 ft from the vacuum pump. These results coincided with the short-term con-
centration (18 ppm) and 8-hour TWA concentration (3.6 ppm) a t Location H. The area
surrounding the vacuum pump assembly was not ventilated; the water tank associated with
the vacuum pump was not covered. Concentrations a t the door to the ACQ-B treating
cylinder ranged from below the detection limit (before the door was opened) to 75 ppm.
Right after the door was opened, three of the four measured concentrations exceeded the
STEL, with the highest just inside the cylinder. Concentrations a t the door dissipated to
between 22 aiid 40 ppm and between 13 and 38 ppm after about 5 and 10 minutes,
respectively, whereas concentrations 15 to 20 ft away from the door were 1 1 to 19 ppm.
After unloading, concentrations within 3 ft of the freshly treated wood surface ranged from
32 to 450 ppm, with the highest detected within 0.5 in of the wood surface. All airborne
ammonia concentrations measured except one exceeded the STEL.
Ammonia concentrations a t the vent ranged from 205 to 700 ppm during initial
vacuum and from 0.1 0% to 0.27% during slow pressure release, blowback, air pressure
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venting, and final vacuum. All airborne concentrations measured both upwind and
downwind under the vent and about 5 to 6 ft above the ground were below the detection
limits.
The ammonia emission from each treatment cycle was calculated from concentra-
tions measured at the vent (Table 10). About 0.25 Ib (1 13.6 g) to 0.35 Ib (1 57.8 g) was
vented during each treatment cycle, but only 0.01 5 Ib (7.0 g) during chemical mixing.
Assuming 2 mixeslday, 3 chargeslday, and 240 working dayslyr, the plant would emit
about 224 Ib (101.4 kg) of ammonia when treating about 280,000 ft3 of commodity.
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Because of ammonia’s volatility and the relatively high pH values in treated wood
(e.g., about pH 8 to 91, a significant amount would be emitted during air drying and stor-
age. One accelerated laboratory study using ten J/* in x % in x J/* in ACQ-B-impregnate0
wood blocks reported 40.57% ammonia loss after 14 days of air drying (20). This loss
may represent a worst-case scenario because the wood blocks in the experiment had much
more available surface area per unit volume for volatilization than do actual commodities
produced. As a result, the emissions from the 280,000-ft3 treated wood should not exceed
24,860 Iblyr (1 1,300 kg/yr), and the total emissions from the treatment operations and the
treated wood should not exceed 25,084 Ib (1 1,400 kg). Thus, ACQ-B treatment would
result in annual emissions of no more than 90,000 Ib from a plant with 1 million ft3 annual
production. This amount would be similar to or less than what would be emitted from a
plant using ammoniacal copper arsenate (ACA) or ammoniacal copper zinc arsenate (ACZA)
when applying the same assumptions for calculations.
Air Emissions during CCA Treatment: The 8-hour, TWA concentrations of airborne arsenic
ranged from 0.01 1 to 0.1 2 mg/m3 (Table 71, which were above the OSHA PEL of
0.01 mg/m3. The highest was at the door to the CCA treating cylinder C (No. 8 in Figure
1 1. Ceiling concentrations ranged from below the limit of quantitation of 0.002 mg/m3 to
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0.14 mg/m3; of eight ceiling samples collected, seven exceeded the NIOSH REL of
0.002 mg/m3.
The higher-than-PEL As concentrations are not typical of the emissions from most
treating plants in the United States (5,331. Dry sweeping of the drip pad area by the
ground man during the air monitoring might have contributed to elevated airborne con-
! : centrations. (Note that wet sweeps or commercial vacuums are usually recommended for
use on drip pads.) Workers did not wear respiratory protection during CCA treatment. The
full-shift exposure of the drip pad loader operator to arsenic during ACQ wood treatment
was 0.0049 mg/m3, less than 50% of the OSHA PEL.
Only 5 of 16 samples contained Cr(VI1 in quantities above the analytical limit of
quantitation, resulting in TWA concentrations below the airborne quantitation limit of
0.001 mg/m3. All full-shift concentrations were below the NIOSH REL and the ACGIH TLV.
Ceiling concentrations ranged from below the airborne quantitation limit of 0.007 mg/m3 to
0.01 5 mg/m3, less than 15% of the OSHA ceiling limit. The full-shift exposures to copper
were less than 80% of the OSHA PEL and NIOSH REL and less than 40% of the ACGIH TLV.
No stack or isokinetic tests were performed during CCA wood treatment. However,
a CCA treatment plant in Virginia that treated four times as much wood as this treating
facility in 1992 emitted only 0.021 Ib As,05/yr (34) (calculated based on an assumption of
operating two 7 ft x 100 ft cylinders and one 6 ft x 50 ft cylinder treating 6,587 charges
per cylinder). A Canadian CCA treatment plant that produced about 40 million board feet
emitted a total of 0.01 6 Ib/yr of arsenic, hexavalent chromium, and copper emissions ( 8 ) .
_. Leaching of Treated Wood
Amounts of Rainfall Applied: Rainfall measured during the leaching tests ranged from
0.6 to 0.9 in per hour, equivalent to 10.5 to 15.7 gal/hr of water falling onto an area of
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3.5 ft x 8 ft. The cumulative rainfall was 14.4 in during a 20-hr test period for ACQ-B-
treated wood units and 16.5 in during 21 hr for CCA-treated wood units. The total water
falling on each ACQ-B-treated, CCA-treated, and control wood unit averaged 25 1 3, 288,
and 251.3 gal, respectively.
Runoff collected varied with time and position of the test units. During the first
r 2 hours of leaching, only 46 to 69% of rainfall was recovered from the bottom of the
ACQ-B-treated and control units and 57 to 67% from the CCA-treated units. Water not
accounted for (about 31 to 54%) was absorbed by wood or entrapped in the gaps between
wood pieces or between wood and the plastic liner. After a few hours, the runoff from
most wood units began to approach the amounts of rainfall falling onto these units except
for wood unit ACQl, where runoff consistently was lower than the rainfall that would have
been falling on that unit, perhaps due to uneven distribution of water by the sprinkler.
Leaching o f CCA-Treated Wood: Table 1 1 shows the As, Cr, and Cu leached from the
CCA-treated wood units during a 24-hr period. Significant amounts of As and Cr were
leached, with arsenic concentrations up to 8.84 mg/L during the first 2 hr, tapering to as
low as 3.89 mg/L in 4 hr and to 2.36 mg/L in 17 hr. After 21 hr, 2.85 to 4.1 1 mg/L was
still detected. Cr leaching was even more severe, ranging from 58.8 to 78.5 mg/L during
the first 2 hr and remaining as high as 23.2 mg/L after 21 hr. Cu leaching was less severe,
with only 3.05 Is 3.84 mg/L detected during the fksr 2 hr and decreasing to 0.78 mg/L
after 21 hr. Trace amounts of As, Cr, and Cu were detected in the runoff samples
collected from'the untreated wood unit, indicating cross-contamination by CCA.
The mass of each active ingredient leached in 24 hr was calculated by adding together
the products of the composite concentration of each sampling interval and the corresponding
runoff volume. Some composite concentrations were estimated based on best-fit curves.
For example, As in the runoff samples that would have been collected during the 7th to the
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17th hr were estimated using the best-fit curves shown in Figure 3. The runoff volumes
were calculated using both measured and estimated values (see footnotes a through c in
Table 1 1). As a result, the mass of active ingredients leached in 24 hr amounted to 0.0083
to 0.0141 Ib for As, 0.0656 to 0.1 03 Ib for Cr, and 0.00277 to 0.00438 Ib for Cu.
Table 12 shows estimates of the percentage loss of each active ingredient in
E 24 hours. The active ingredients absorbed by the wood units were estimated by multiplying
the specific retention (average of two retention analyses) of each ingredient by the wood
volume having CCA penetration. The wood volume having CCA penetration was estimated
by assuming a uniform distribution of CCA only in the outer 1 -in thickness of each timber
piece (Figure 41, and that only sapwood had CCA penetration. The volume fraction with
CCA retention (or sapwood fraction) was 56.5%, which was close to the treatment plant
operator‘s estimates (Le., 50%).
Using these assumptions, the amounts of metal oxides absorbed by one wood unit
were calculated to be 8.08 Ib of As205, 11.78 Ib of CrO,, and 4.37 Ib of CuO (or 5.27 Ib of
As, 6.13 Ib of Cr, and 3.49 Ib of CUI. The percentage oxide loss during the first 24 hr
ranged from 0.1 6% to 0.27% for As, from 1.08% to 1.67% for Cr, and from 0.08% to
0.13% for Cu. Jin and Preston (231 reported 9.45, 0.35, and 2.42% loss for As, Cr, and
Cu, respectively, when leaching treated wood blocks using the much more severe leaching
procedure specified by AWPA (El 1-87 Standard).
Assuming a uniform distribution of CCA in the outer 142 thickness, the cumulative
fraction of CCA retention would increase exponentially as the distance from the wood sur-
face increased,exponentially. For example, 0.61, 6.03, and 55.36% of CCA would be
retained in the outer 0.005-, 0.05-, and 0.5-in thickness, respectively. Because leaching of
active ingredients requires contact with water and because only 0.08% to 1.67% of As, Cr,
and Cu was leached, the leaching might have occurred to no more than 0.013 in deep (or
0.048 in deep for ACQ-B-treated wood). The bulk of the wood remained unleached.
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TOC ranging from 78.8 to 279 mg/L in the runoff samples was attributed to water-
soluble wood organics because the untreated wood unit samples contained up to 176 mg/L
of TOC. Some of these organic substances can be low-molecular-weight sugars, carbo-
hydrates, and phenolic-containing lignin components (29). A small amount of TKN was
detected in the runoff samples of the treated Le., 1.8 to 7.0 mg/L) and the untreated (i.e.,
1.75 to 9.8 mg/L) wood units, indicating leaching of some nitrogen-containing wood E '
organics. Leached wood organics are biodegradable and thus are not considered environ-
mental contaminants.
Leaching of ACQ-B-Treated Wood: Cu concentrations leached from the ACQ-B-treated
units ranged from 117 to 288 mg/L during the first 5 hr, but tapered to 28.7 to 72.2 mg/L
after 20 hr (Table 13). TKN, analyzed only for three sampling periods, was up to 620 mg/L
and decreased to 154 to 265 mg/L after 15 hours. TOC, as high as 890 mg/L during the
first sampling interval, reduced to 170 to 382 mg/L after 15 hours. The TKN was attri-
buted primarily to ammonium (NH,+) and didecyldimethlyammonium (DDA) ions and, to a
much lesser extent, to nitrogen-containing wood organics. The TOC comprised mainly the
organic carbons of water-soluble wood organics and DDA (not quantified). Because low-
molecular-weight acidic components and partially acidic and phenolic components are
subjected to more severe leaching under alkaline conditions (71, such wood organics might
account for more TOC than that analyzed in the CCA and control runoff samples.
The mass of Cu, TKN, and TOC leached in 24 hr was calculated/estimated as done
for CCA. The mass leached amounted to 0.149 to 0.221 Ib as Cu, 0.447 to 0.534 Ib as
TKN, and 0.605 to 0.767 Ib as TOC. The amount of CuO absorbed by 1 ft3 of sapwood
was 0.57 Ib/ft3; the total Cu absorbed was 27.05 Ib as CuO (or 21.61 Ib as CUI (Table 14).
Consequently, the percentage Cu loss was 1.02% for ACQ1 and 0.69% for ACQ2 (average
0.86%). These values were much lower than the 14.69% reported (23).
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The quat retention in 1 ft3 of sapwood was 0.28 Ib/ft3 as DDAC; the total quat
absorbed was 13.29 Ib as DDAC (or 11.99 Ib as DDA or 0.62 Ib as NH,). Because the
TOCs leached had been estimated to be 0.767 and 0.605 Ib (as C) for ACQl and ACQ2,
respectively, and some were attributed to wood organics, the largest TOC attributable to
quat would be 0.535 and 0.373 Ib (as C), or 0.662 and 0.461 lb (as DDA), for ACQl and
f : ACQ2, respectively. Therefore, the percentage quat (as DDA) loss would be no more than
5.52 and 3.84% for ACQl and ACQ2, respectively (average 4.68%). These values are
higher than the 3.27% value reported (23); the discrepancy has already been explained.
The ammonia retention by 1 ft3 of sapwood was 0.57 Ib/ft3 (as NH,); therefore, the
tctal ammonia absorbed was 27.05 Ib (as NH,). Assuming the percentage ammonia loss
was less than 40.57% (20) as discussed previously, more than 59.43%, or > 16.07 Ib
ammonia (as NH,) remained in the sapwood. As estimated, the TKN leaching loss was
0.534 and 0.447 Ib (as N) for ACQl and ACQ2, respectively, equivalent to 0.648 and
0.543 Ib (as NH,) for ACQ1 and ACQ2, respectively, among which 0.034 to 0.024 Ib (as
NH,) was associated with quat molecules (or DDA ions). Therefore, the TKN associated
with NH,+ ions was 0.61 4 and 0.51 9 Ib (as NH,) for ACQl and ACQ2, respectively. The
percentage NH, loss was estimated to be 3.82 and 3.23% for ACQ1 and ACQ2, respec-
tively (average 3.53%).
The runoff sample pH values ranged from 8.86 to 9.04. The treated wood pt?
should be slightly higher. Ammonia a t this pH value exists in about equal amourmcs as NH,
and NH,+ (26). The volatile NH, was depleted during air drying and storage. The water-
soluble NH4+ ioiis could be leaching when exposed to rainfall. Jin (20) reported up to 19%
loss of ammonia due to leaching (vs. 3.2 to 3.8% by this study). Again, the discrepancy
was attributed to the different leaching methods used.
I ' J 1 3 1 1 1 1 1 1 1 1 J I IJ 1 1 1
-1 1
15
Yearly CCA and ACQ-B Losses Due to Leaching: For small-sized plants with an annual
production of 1 million ft3 (or about 20 million board feet), the CCA-treated materials at
0.4 lb/V retention could release 160 Ib of As205, 1,508 Ib of CrO,, and 42 Ib of CuO to
the environment every year (Table 15). For medium- and large-sized plants, the annual
releases might be linearly extrapolated. Converting from CCA to ACQ-B could significantly
p : reduce the.release of As and Cr, but releases of other contaminants could increase greatly.
For example, a small-sized plant with an annual production of 1 million ft3 of ACQ-B-treated
materials (at 0.4 Ib/ft retention) could release 1,297 Ib of CuO, 2,543 Ib of TOC (inclusive
of extractable wood organics and quat [as DDAI), and 3,174 Ib of NH4+ per year. The
releases were calculated based on exposure of treated rough-cut timber to about 18 in of
rainfall 4 days after treatment, i.e., conditions more severe than what would be expected to
occur naturally.
CONCLUSIONS
The types of wastestreams generated by the CCA and ACQ treatment systems vary
in species, concentrations, amounts released, and the associated health and ecological
impacts. Thus, a direct comparison of reductions of similar wastes is not easy. There is no
common denominator to determine improvements on an absolute scale. However, we can
compare the two sets of data and draw relative significance.
The most important change in environmental emissions from using ACQ is the com-
piete elimination.of arsenic and chromium use, which eliminates the generation of RCRA
wastes and the risk of contaminating the environment with these RCRA metals. Because
most treating facilities are self-contained in that they recycle all wastewater produced
within the plant and on the drip pads, no liquid waste problems need t o be addressed.
Using ACQ Type B formlation (ACQ-B) produces more air emissions, mainly as NH,. A
r
I 1 1 1 - 1 1 1
1 a I 1 1
-I -I
16
plant with an annual production of 1 million 13, (or about 20 million board feet) could
release 90,000 Ib of NH, per year from ACQ-B treatment operations and the treated wood.
In contrast, a CCA plant that produced four times as much commodities released only
c 0.021 Ib of As,05 and trace amounts of CrO, and CuO annually. During the air monitor-
ing, however, airborne concentrations of inorganic arsenic exceeded the OSHA PEL of
:: 0.01 mg/m3 among all workers and in all monitoring locations. Dry sweeping of the drip
pad might have contributed to the elevated concentrations. Full-shift exposures to ammonia
during ACQ-B treatment were below applicable exposure limits. Ceiling exposures to
ammonia during unloading of the ACQ-B treating cylinder exceeded the 35 ppm STEL,
requiring workers in the immediate area to use appropriate respiratory protection.
Engineering controls should be considered to reduce ceiling exposures.
The treated wood, after transfer from the drip pads to the outside storage yard,
could be a major source of contamination to the environment. For a plant with an annual
production of 1 million ft3 (or 20 million board feet) of CCA-treated wood a t 0.4 Ib/ft3
retention, 160 Ib of As205, 1,508 Ib of CrO,, and 42 Ib of CuO could be washed away by
stormwater every year. For the same amount of ACQ-B-treated wood a t the same reten-
tion, 1,297 Ib of CuO, 2,543 Ib of TOC (inclusive of extractable wood organics and quat
[as DDAI), and 3,174 Ib of NH,' ccluld be released into the stormwater runoff every year.
These releases were estimated based on exposure of treated rough-cut timber to about 18
in of rainfall 4 da!, s after treatment; these conditions are more severe than what would be
expected to occur naturally. Leaching studies using less severe test conditions are curamly
under way. - I '
LITERATURE CITED
1. American Wood-Preservers' Association. 1 992. Book of Standards. Woodstock, Md.
1 7
7 2.
3.
7 4.
1
1 I I
1 1 1
-)I
!: 5.
6.
7.
8.
9.
10 .
11 .
12.
13 .
14 . 15 .
16.
17.
18.
19.
20.
21.
American Wood-Preservers' Association. 1 990. Wood Preservative Statistics. 1 988 AWPA Proceedings, Woodstock, Md. Archer, K. J., L. Jin, A. F. Preston, N . G. Richardson, D. B. Thies, and A. R . Zahora. 1992. ACQ: Proposal t o the American Wood Preservers' Association Treatment Committee to Include Ammoniacal Copper Quat, ACQ Type B, in AWPA Standards under the Jurisdiction of t he Treatments Committee. Chemical Specialties, Inc., Charlotte, N.C. Baldwin, W. J. 1992 . Reuse of wood preservative that contains arsenic. Proc. Arsenic & Mercury: Workshop on Removal, Recovery, Treatment, and Disposal. EPA/600/R-92/105, U.S. EPA Office of Research and Development, Washington, D.C. Baldwin, W. J . 1983. The use of arsenic a s a wood preservative. In W. H. Lederer (Ed.), Arsenic: Industrial, Biomedical, and Environmental Perspectives. Van Nostrand Reinhold Company, New York, N.Y. pp. 103-1 04. Barnes, H. M., and D. D. Nicholas. 1992. Alternative preservative systems: Pros & cons. Proceedings of the Arsenic & Mercury: Workshop on Removal, Recovery, Treatment, and Disposal. EPA/600/R-92/105, U.S. EPA Office of Research and Development, Washington, D.C. Browning, B. L. 1987 . Methods of Wood Chemistry, Vol. II. lnterscience Publishers, a division of John Wiley & Sons, New York, N.Y. Chemical Specialties, lnc. 1 9 9 3 . Emission Compliance Survey Monitoring Report of a Canadian Treatment Plant. CSI, Charlotte, N.C. Chemical Specialties, Inc. 1992 . ACQ 21 00 Wood Preservative Operator's Manual. CSI, Charlotte, N.C. Chen, A. S. C. 1994 . Evaluating ACQ a s an Alternative Wood Preservative System. U.S. Environmental Protection Agency, Risk Reduction Engineering Laboratory, Cincinnati, Ohio, EPA/600/SR-94/036. Chen, A. S. C., and L. S. Walters. 1979. The fate of arsenic in pressure-treated southern pine plywood subjected to heavy artificial rainfall. Proceedings of the American Wood-Preservers' Association 75: 1 1 8-1 61. Da Costa, E. W. B. 1967 . Laboratory evaluation of wood preservatives: Part I. Effectiveness of waterborne preservatives against decay fungi after severe leaching. Holzforschung 21 :50-57. Fahlstrom, G. B., P. E. Gunning, and J. A. Carlson. 1957. Copper-chrome-arsenate wood preservatives: A study of the influence of composition on leachability. Forest Products Journal 17 : 17-22. Federal Register. 1992 . U.S. Government Printing Office, December 24. p. 61 492 . Findlay, D. M., and N . G. Richardson. 1983 . Wood Treatment Composition. Canadian Patent 1 ,146 ,704 . Findlay, D. V., and N. G . Richardson. 1990 . Wood Treatment Composition. U.S. Patent 4,929,354. Hager, B. 1 969. Leaching tes t s on copper-chromium-arsenic preservatives. Forest Products Journal 19:21-26. Henry, W. T., and E. B. Jeroski. 1967. Relationship of arsenic concentration to the leachability of chromated copper arsenate formulations. Journal of the American Wood-Preservers' Association 63: 1 87-1 96. Hosli, J. P., and K. Mannion. 1991. A practical method to evaluate the dimensional stability of wood and wood products. Forest Products Journal 4 1 (3):40-44. Jin, L. 1993 . Data on Ammonia Loss during Air Drying Process. CSI Report, Harrisburg, N.C. Jin, L., and K. J. Archer. 1 9 9 1 . Copper-based wood preservatives: Observations on fixation, distribution, and performance. Proceedings of the American Wood-Preservers' Association, 87 : 16.
1
1 1
1 1 1 1 1 1 1 I It 1 1 1 1
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18
22. Jin, L., K. J. Archer, and A. F. Preston. 1992. Depletion and biodeterioration studies with developmental wood preservative formulations. Proceedings of the American Wood-Preservers' Association 88: 1 08-1 25.
23. Jin, L., and A. F. Preston. 1993. Depletion of preservatives from treated wood: Results from laboratory, fungus cellar, and field tests. Paper presented a t 2nd International Symposium of Wood Preservation, Cannes-Mandelieu, France.
24. Jin, L., and A. F. Preston. 1991. The interaction of wood preservatives with lignocellulosic substrates. I. Quaternary ammonium compounds. Holzforschung
25. Loebenstein, J. R. 1992. Arsenic: Supply, demand, and the environment. Proc. 45(6):455-459.
Arsenic & Mercury: Workshop on Removal, Recovery, Treatment, and Disposal. $ 7 Alexandria, Va., August 17-20.
26. Morel, F. M. M. 1983. Principles of Aquatic Chemistry. Wiley-Interscience Publication, John Wiley & Sons, New York, N.Y.
27. Nicholas, D. D., A. D. Williams, A. F. Preston, and S. Zhang. 1991. Distribution and permanency of didecyldimethylammonium chloride in southern pine sapwood treated by the full-cell process. Forest Products Journal 41 (1 ):41-45.
28. NIOSH. 1990. Pocket Guide to Chemical Hazards. U.S. Department of Health and Human Services, Centers for Disease Control, National Institute for Occupational Safety and Health (NIOSH), Cincinnati, Ohio.
29. Panshin, A. J., and C. de Zeeuw. 1970. Textbook of Wood Technology, Vol. 1. Structure, Identification, Uses, and Properties of the Commercial Woods of the United States and Canada. McGraw-Hill Book Company, New York, N.Y.
30. Science News. 1992. Arsenic in water: Bigger cancer threat. p. 253 (April 18). 31. Smith, D. N. R., and A. I. Williams. 1973. The effect of composition on the
effectiveness and fixation of copper/chrome/arsenic and copper/chrome preservatives: Part 11: Selective absorption and fixation. Wood Science and Technology 7: 142-1 50.
32. Teichman, T., and J. L. Monkman. 1966. An investigation of inorganic wood preservatives: Part I. The stability to extraction of arsenic impregnated hardwood. Holzforschung 20: 125-1 27.
33. Todd, A. S. et al. 1983. Industrial Hygiene Surveys of Occupational Exposure to Wood Preservative Chemicals. NIOSH Technical Report No. 83-1 06.
34. U.S. Environmental Protection Agency (EPA). 1 993. Waste Minimization Practices a t Two CCA Wood-Treatment Plants. EPA/600/R-93/168. U.S. EPA, Risk Reduction Engineering Laboratory, Office of Research and Development, Cincinnati, Ohio.
35. U.S. Environmental Protection Agency. 1 993. Guides to Pollution Prevention: Wood Preserving Industry. EPA/625/R-93/014. U.S. EPA, Risk Reduction Research Engineering Laboratory and Center for Environmental Research Information, Office of Research and Development, Cincinnati, Ohio.
36. U.S. Environmental Protection Agency (EPA). 1 992. Contaminants and Remedial Options at Wood Preserving Sites. EPA/600/R-92/182. U.S. EPA, Risk Reduction Engineering Laboratory, Office of Research and Development, Cincinnati, Ohio.
37. U.S. Environmental Protection Agency (EPA). 1 99 1. Inorganic Arsenicals: Technical Support Document. U.S. EPA, Office of Pesticides and Toxic Substances, Office of Pesticide Programs, Washington, D.C.
Sequoya solution storage tank Design wood solution storage tank CCA process tank Freshwater storage tank CCA work tank B CCA work tank A CCA concentrate tank CCA cylinder for low retention treatment CCA cylinder for high retention treatment ACQ-B cylinder No. 8 cylinder combo tank No. 9 cylinder combo tank No. 10 cylinder combo tank Boiler 1 Boiler 2 ACQ-B work tank Floor pit 1 (not operational) Floor pit 2 (not operational) Control panel 1 Control panel 2 Laboratory CCA vacuum pump assembly ACQ-B vacuum pump assembly Ammoniacal copper concentrate tank Quat concentrate tote NH, concentrate tote'"' CCA concentrate quick coupler Ammoniacal Cu concentrate quick coupler CCA cylinder door pit ACQ-B cylinder door pit Screen to 2 f t x 2 f t x 2 f t box Screen to 2 f t x 2 f t x 2 f t box Track Track Staircase Ramp from basement level to ground level Storage area Machine shop Steam drying cylinder Track DOT hazalflous waste drum Floor sump ACQ-B vent
9.2 ft x 16 ft 9.2 ft x 16 f t 9.2 ft x 16 f t 9 .2 f t x 1 6 f t 9.2 f t x 16 f t 9.2 f t x 16 f t 8 f t x 1 6 f t 6 f t x 66 f t 6 f t x 40 f t 6 f t x 40 f t
46in x 1 6 f t 3 8 i n x 1 6 f t 3 8 i n x 1 6 f t
9 .2 f t x 1 6 f t
8,000 8,000 8,000 8,000 8,000 8,000 6,000
14,000 8,500 8,500 2,200 1,200 1,200
8,000
8 f t x 16 ft 6,000 3.3 f t x 3.3 f t x 3.3 f t 275 3.3 ft x 3.3 f t x 3.3 f t 275
140 f t 80 f t
6 f t x 55 f t 11,500
~ ~ ~~ ~~ ~~
(a) Will not be used during commercial production.
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‘ 1 -1 LI
TABLE 2. ACQ-B SOLUTION COMPOSITIONS
Charge Number
Composition A9 A1 0 A1 1 Target
Cu (% by wt., as CuO) 0.95 0.79 0.98 1 .OO(b’
quat (% by wt., as DDACla)) 0.36 0.54 0.50 0.50‘c’
NH, (% by wt., as NH,) 1.13 1.08 1.23 1 .oo CuOIquat 2.6 1.5 2.0 2.0
NH,/CUO 1.2 1.4 1.3 1 .o * . I .
Total active ingredients (% by wt.) 1.31 1.33 1.48 1.50
(a) Didecyldimethylammonium chloride (b) AWPA Standard P5-92: minimum 0.93%; maximum 1.07% (1). (c) AWPA Standard P5-92: minimum 0.44%; maximum 0.57% (1).
I I .I
TABLE 3. TYPICAL CCA SOLUTION COMPOSITIONS")
Charge Numberfb1 AWPA StandardIc1
Composition B 357 0 383 6 437 Target min (YO) max (%I
Cr (% by wt., as CrO,) 0.728 0.730 0.723 CrO, (%I . 48.0 48.3 48.0 44.5 50.5
Cu (% by wt., as CuO) 0.261 0.256 0.257 CUO (%I 17.2 16.9 17.1
As (% by wt., as 0.527 0.526 0.526
As205 ( % I Total (% by wt.) 1.516 1.51 1 Total (%I 100.0 100.0 100.0
f ' 34.8 34.8 34.9
1.506 1.5
17.0 21 .o
30.0 38.0
~~
(a) (b)
(c)
CCA solutions for treatment charges of the present study were not analyzed. Treatment occurred on September 7 , September 15, and October 1 1, 1993 for charge nos. B 357, B 383, and B 437, respectively. AWPA Standard P5-92, Standards for Waterborne Preservatives: CCA-Type C (1 1,
TABLE 4. UPTAKE AND RETENTION DURING ACQ-B TREATMENT
~
Charge Number
A7"' A9'b' A1 Olb' A1 l'b'
ACQ-B Workina Solution Active ingredientstc' (%) NIA 1.31 1.33 1.5 Specific gravity NIA 1.01 11 1.0113 1.01 30 Active ingredients per gallon of solution NIA 0.1 105 0.1 122 0.1268
ACQ-B uptakeId1 (gal) 600 915 495 1200 (Iblgall
Total active ingredients absorbed (Ib) NIA 101.11 55.54 152.16
(a) Treated on September 24, 1993. (b) Treated on September 28, 1993. (e) Estimated sapwood volume was used to calculate ACQ retention. (f) Calculated ACQ-B retention = (Total active ingredients absorbed)/(Estimated sapwood volume). (g) CuOIquat ratio was approximately 2:l. (h) x120 = number out of 20 wood borings with penetration to 2.5 in of wood or 85% of sapwood. NIA = data not available.
(c) Analyzed by CSI Laboratory. (d) Solution absorbed by wood.
TABLE 5. UPTAKE AND RETENTION DURING CCA TREATMENT"'
Charge Number
8364 C129 8365 C130 8366 C131
CCA Workinn Solution Active ingredients Ib) 1%) 1.5 1.8 1.5 '1 .8 1.5 1.8 Specific gravity 1.0131 1.01 56 1.0131 1.01 31 1.01 56 1.01 56 Active ingredients per gallon of solution (Iblgal) 0.1263 0.1520 0.1263 0.1520 0.1263 0.1520 CCA uptake(') (gal) 594 1220 594 1284 864 1485 Total active ingredients absorbed (Ib) 75.02 185.44 75.02 195.17 109.30 225.72
(a) Treatment occurred on September 8, 1993. (b) Because CCA solutions were not analyzed, target concentrations were used for calculations. (c) Solution absorbed by wood. (d) Estimated sapwood volume was used to calculate CCA retention. (e) Calculated CCA retention = (Total active ingredients absorbed)/(Estimated sapwood volume).
i i L4 .I I I
I. r' I TABLE 6. SAMPLING LOCATIONS AND ANALYTICAL METHODS
~-
Sampling Sampling Analytical Matrix L0catiod.l Parameter Type Method(s1
Sampling locations (see Figure 1 ): Approximately 1 ft south of CCA process tank (No. 3). about 5 f t above the basement floor. Approximately 4 ft from door to CCA treating cylinder (No. 81, on nearby ledge. On top of file cabinet adjacent to control panel (No. 19). about 5 f t above the basement floor. Samplers worn by the treatment plant operator, the drip pad loader operator, and the drip pad ground man. Between ammoniacal copper concentrate tank (No. 241 and quat concentrate tote (No. 251, about 5 f t above the drip pad floor. Approximately 4 f t from door to ACQ-B treating cylinder (No. l o ) , on nearby ledge.
G - Approximately 5 f t west of ACQ-B combo tank (No. 13). against north wall of the basement, about 4 ft above the basement floor.
H - About 1 f t above and 4 f t south of the ACQ-B vacuum pump assembly (No. 23).
I - Samplers worn by the treatment plant operator, the drip pad loader operator, the drip pad ground man, the yard boss, and the outside loader operator.
J - CCA chemical delivery area (No. 27). K - CCA concentiate storage area (No. 7) . L - CCA work tanks area (No. 5 and No. 6). M - CCA combo tanks area (No. 11 and No. 12).
N - Tracking from CCA treatmenf cylinders (No. 8 and No. 9) to CCA drip pad.
0 - ACQ-B chemical delivery area (No. 28). P - Ammoniacal copper concentrate tank area
(No. 24). Q - Quat and NH2 concentrate totes area (No. 25 and
No. 26). ACQ-B combo tank area (No. 13). ACQ-B work tank area (No. 16). Tracking from ACQ-B treatment cylinder (No. 10) to ACQ-B drip pad. Samples collected from 32-gal plastic containers. Duplicate sample collected at sampling locations A and B. Duplicate sample collected at sampling location F. No sampling performed: observation of drips and spills recorded. Samples collected from two treated wood units at several time intervals. Including As, Cr. and Cu. Total Kjeldahl nitrogen. Total organic carbon. As analyzed using EPA 7060.
NIA - not applicable
. -
.-,
TABLE 7. RESULTS OF AMBIENT AIR QUALITY MONITORING
(b) For each person or area monitored, the top figure is the full-shift concentration and the bottom figure is a short-term or 16-min concentration. (c) 8-hour airborne concentration, calcillated as the time-weicnted average of the long-term and short-term concentrations. td) Only the long-term concentrations were used for each TWA calculation.
'T I r-
't r -
r ' I J . I -1 1 1
. I 1 1 I I 1 I I 11
-1 '1
TABLE 8. PELS, RELs, AND TLVs FOR As, Cr(VI1, Cu, AND NH,
The Occupational Safety and Health Administration (OSHA) permissible exposure limits (PELS) are timeweighted average (TWAI concentrations that must not be exceeded during any 8-hr workshift of a 40-hr workweek. The National Institute for Occupational Safety and Health (NIOSHI-recommended exposure limits (RELs) are TWA concentrations for up to a 10-hr workday during a 40-hr workweek. The American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVsl are 8-hr TWA concentrations. Ceiling concentration. The ceiling value is assessed as a 15-min TWA exposure. Suspect carcinogen. Occupational carcinogen. 1 ppm = 0.71 mg/m3. Short-term exposure limit.
(a) Based on an assumption that ACQ wes uniformly retained in the outer 1" of each of the 4 2 6 in x 6 in x 8 ft timber pieces.
(b) Volume fraction with ACQ retention. (cl Volume fraction without ACQ retention. (dl DDAC = ididecyldimethylammonium chloride (formula wt. = 362.08) (e) DDA = didecyldimethylammonium ion (formula wt. = 326.63) (f) Less TOC in control samples. (The TOC attributable to wood organics in ACQ samples most likely would
be higher than the TOC in the control samples. Therefore, the percentage quat loss calculated most likely would be overestimated.)
(g) Amount of N (as NH,) associated with DDA. (hl NH, retention assumed to be identical to CuO retention. (i) Assumed to be 40.57%.
-1
c
,
J I I I 1 1 1 1 1 1
TABLE 15. YEARLY CCA AND ACQ-B LOSSES DUE TO
CCA lnoredients As (as As205) Cr (as 00,) Cu (as CuO)
