bar, and board. Operators also change the caul plates, which emboss various patterns onto the board, several times a day. If the operators are forced to work inside a press enclosure, then they will be exposed to hot, foggy conditions in an unsafe, if not uninhabitable, workplace. The commenter noted that they have considered video cameras or automation, but no technique is available that could completely replace the operators. The commenter provided a video 2 47 demonstrating the duties of the operators on November 15, 2002 and stated that this is not a problem that can be easily overcome.

The commenter argued that because the hardboard mat is not completely dried and the resin is not set in the press, a significant amount of VOCs exit the press with the board and are emitted from the bake oven. Therefore, the emissions from the short cycle presses are "

highvolume very high moisture, relatively low temperature, and have low concentrations of VOCs and HAPs" and the bake oven emissions are " lower volume, higher concentration exhaust gases."

Because of these factors, the commenter noted that the emissions from the presses at this facility are a smaller portion of the overall emissions than the press emissions at other hardboard plants.

Table 2 2 summarizes total HAP ( sum of the six predominant HAP) emissions and exhaust gas characteristics for one production line based on stack tests performed in December 2002. The commenter noted that press total HAP emissions were equivalent to 0.52 lb/ thousand square foot ( MSF), 7/ 16 inch ( equivalent to 0.89 lb/ MSF, 3/ 4 inch) and the bake oven total HAP emissions are equivalent to 0.46 lb/ MSF, 7/ 16 inch ( equivalent to 0.13 lb/ MSF, 1/ 8 inch). ( No thickness basis for these measurements was provided in the comment letter; however the thicknesses were later provided during a meeting with the commenter. 8) The commenter pointed out that the total HAP emissions from one press at this facility are above the 20 ppmv limit by less than 3 ppmv, but there is no consistent way that the facility can ensure that they could keep emissions below 20 ppmv. The commenter noted that the hardboard market is highly competitive, and individual facilities work to minimize chemical and production costs. There are currently no real opportunities for raw material substitution, and it seems unlikely that practical and cost efficient pollution prevention options will be available any time soon. 2 48 Table 2 2. Total HAP Emissions Exhaust Gas Characteristics for one wet/ wet Hardboard Production Line Parameter Press Bake oven Sum of total HAP, ppmv 22.8 61.3 Sum of total HAP, lb/ hr 14.50 12.76 Stack temperature, ° F 137 211 Stack gas flow, cfm 99,629 39,740 Stack moisture, % 14.1 20.0 Commenter IV D 57 stated that controlling two wet/ wet process short cycle hardboard presses will be very costly. The total exhaust is 200,000 actual cubic feet per minute ( acfm), so the RTOs will have to be large and will require large amounts of natural gas. In addition, 10,000 pounds of water vapor per day will have to be raised from about 140 º F to the temperature necessary for destruction of the HAP. The commenter estimated that capital costs for the press controls alone will be $ 5.7 to $ 9.6 million and annualized costs will be about $ 3 million, and only 120 tpy of HAP ( 60 tpy per press) will be controlled. The commenter noted that this facility is unique among wet/ wet process hardboard facilities because the hardboard is completely dried in a bake oven rather than the press. As a result, the facility will have to control the bake oven as well as the press, while other wet/ wet process hardboard facilities will only have to control one unit,

putting this facility at an economic disadvantage.

The commenter noted that the high levels of moisture in the emissions would quickly degrade the media in an RTO or an RCO. Also, this facility would need an extremely large RTO or RCO unit to handle all of the emissions from the presses. Another possible control device is a biofilter, but the commenter believes that biofilters are untested and impracticable for a gas volume as large as that of their facility's press vents. The commenter pointed out that according to the BID, a biofilter large enough to handle the 200,000 acfm of exhaust would have to have a surface area of 24,000 ft2 to 40,000 ft2, and the BID notes that a 6,000 ft2 Monsanto unit is considered a " large" biofilter. If this facility were to attempt to use six foot diameter biocubes,

857 to 1,428 biocubes would be required. At costs ranging from $ 27,000/ ton of HAP removed 2 49 ( using a wet scrubber and biofilter) to $ 35,000/ ton of HAP removed ( using a wet scrubber and RCO), any control device chosen for this facility will be extremely expensive and would exceed reasonable BACT cost standards. No controls would be the best VOC/ HAP emission control option for the facility.

The commenter suggested two possible solutions to this problem. The preferred option is to separate hardboard presses, or at least wet/ wet process hardboard presses, into a new subcategory and determine that the MACT floor for this subcategory is " no control."

Beyondthe floor controls should not be considered because they are too costly. If EPA decides not to create a separate subcategory, then it should exclude short cycle wet presses that do not dry the board and set the resin, such as the ones at this facility, from the MACT requirements. If EPA chooses to exclude the short cycle presses, then the following statement should be included in the definition of " reconstituted wood product press:" " It does not include a hardboard press where the daily average moisture content of the board leaving the press is equal to or greater than 20%

by weight ( dry basis)."

Response: When we determined the MACT floor at proposal, we grouped process units based on similarities in equipment design, operation, and emissions. We grouped the wet/ wet hardboard presses with other types of hardboard presses at proposal for several reasons: ( 1)

wet/ wet hardboard presses manufacture the same product as presses at dry/ dry and wet/ dry hardboard plants; ( 2) wet/ wet and dry/ dry hardboard manufacturing uses phenol formaldehyde resins; and ( 3) the presses at wet/ wet hardboard plants have emissions similar to those from presses at wet/ dry and dry/ dry process hardboard plants. We also grouped all hardboard presses with presses used to manufacture MDF, particleboard, and OSB because these presses are of similar design ( generally multiplaten presses with loader and unloader) and have HAP emissions of the same magnitude. There was no reason to believe that APCD applicability varied according to product because similar types of enclosures and add on controls were used on multiple presses making each reconstituted wood product ( hardboard, MDF, particleboard, and OSB). We distinguished among plywood presses and reconstituted wood product presses because of different emissions characteristics ( i. e., plywood press emissions are much lower) and factors that could affect the ability of plywood presses to be enclosed ( i. e., the fact that plywood presses are often manually loaded and unloaded and require constant forklift access for removal of stacks of 2 50 pressed plywood). We determined that the MACT floor for new and existing reconstituted wood product presses is the emission reduction achievable with a control system that incorporates an enclosure and incineration based controls or biofilters. We determined that the MACT floor for plywood presses is no emissions reduction because no plywood presses are controlled.

Documentation of the proposed process unit groups and MACT floor determinations for each group was provided in a memorandum entitled " Determination of MACT floors and MACT for the Plywood and Composite Wood Products Industry." 3 We disagree that there is sufficient technical rationale for treating wet/ wet hardboard presses or all hardboard presses differently for purposes of determining that MACT floor. While there may be some reasons for treating wet/ wet hardboard presses separately ( i. e., wet mat pressed), there are also reasons for not treating them separately ( i. e., high emissions compared to other reconstituted wood products presses). The final PCWP rule applies uniformly to all reconstituted wood products presses, including wet/ wet hardboard presses. The following discussion explains our rationale and addresses specific points raised by the commenter.

The commenter correctly noted that hardboard presses have their own AP 42 chapter;

however, the other PCWP ( including MDF, OSB, particleboard, plywood, and engineered wood products) also have their own AP 42 chapters. Previous EPA publications, such as AP 42 emission factors, were not a consideration in determining the PCWP MACT process unit groups.

Similarly, while we acknowledge that there are separate effluent guidelines for wet process hardboard ( because wet process hardboard, including wet/ wet and wet/ dry hardboard processes,

is the only PCWP production process that uses water), we note that the these effluent guidelines were developed pursuant to the Clean Water Act and were not a considered when determining the PCWP MACT process unit groups.

The commenter claimed that hardboard presses have lower emission rates than other reconstituted wood products presses, and stated that wet/ wet hardboard presses have a much higher exhaust gas flow and a much lower exhaust gas temperature than other hardboard presses.

Our data do not support these conclusions. Our data show that hardboard presses, including wet/ wet hardboard presses, have some of the highest uncontrolled HAP emission factors ( e. g., 2.2 and 3.0 lb/ MSF 3/ 4") within the reconstituted press grouping, which has total HAP emissions ranging from ( 0.37 to 3.0 lb/ MSF 3/ 4"). The PBCO for the reconstituted wood product presses, 2 51 which was based on the maximum of our uncontrolled total HAP data, was based on the emissions of a wet/ wet hardboard press. 9 The total HAP emissions from the commenter's press ( 0.89 lb/ MSF 3/ 4") are lower than some of the other wet/ wet hardboard presses for which we have data, but are within the range of emissions from reconstituted wood products presses. In terms of annual emissions, the commenter's wet/ wet hardboard presses each emit 60 tpy of HAP. In addition, our MACT survey data do not show a large difference in the press exhaust flows and temperatures from wet/ wet hardboard presses and other types of reconstituted wood products presses. 10 We acknowledge that wet/ wet hardboard presses differ from other types of reconstituted wood products presses because wet/ wet hardboard presses are used to press a wet mat. Wet/ wet hardboard presses have water that cascades down the sides of the press as the press closes. The commenter presented concerns regarding potential difficulty with a full enclosure for the subject facility, including equipment degradation, disruption of water flow, and operator safety concerns.

Given that none of the other companies with wet/ wet hardboard presses presented these concerns to us, we are not able to distinguish which of these concerns are specific to the commenter's facility and which could be problems for other wet/ wet hardboard presses. Also, it is unclear how pressing equipment that has water cascading down its sides during normal operation could be adversely affected by a low temperature, high moisture environment inside an enclosure. We acknowledge that safety of the operators inside an enclosure at the subject facility is a major concern. Although a wood products enclosure is required to meet the MACT floor, the final PCWP rule includes alternative options that would minimize operator safety concerns. For example, another process unit could be controlled and used in an emissions average to avoid capturing and controlling all of the press emissions. Another option would be to construct and test a partial wood products enclosure and use a highly efficient control device to achieve a combined capture and control efficiency of 90 percent. In the video provided by the commenter,

the press exhaust appears to be very buoyant, rising rapidly within the press hood. The vapor cloud does not appear to spread outside of the hooded area, making it seem feasible that the facility could achieve good capture using a partial wood products enclosure.

The commenter stated that their facility is unique among wet/ wet hardboard facilities because the facility uses a short press cycle ( 5 minutes or less) and uses bake ovens to complete 2 52 drying of the board to bone dry levels. According to the commenter, other facilities press for up to 28 minutes and do not have bake ovens because the board is pressed to bone dry levels. We cannot conclude with certainty that the commenter's facility is unique because our MACT survey data do not verify the commenter's statements. Our MACT survey data show that there is at least one other wet/ wet hardboard facility with bake ovens. The survey data also show that other wet/ wet facilities use short press cycles, ranging from 4 to 20 minutes. We do not have data on board outlet moisture content.

The commenter noted that the sum of " total HAP" for their wet/ wet presses is above 20 ppm. From this comment, we infer that the commenter believed that they would almost be able to comply with the 20 ppm compliance option in the proposed rule. If so, it appears that the commenter misunderstood the application of the 20 ppm compliance option in the PCWP rule.

The 20 ppm value is in terms of THC, not " total HAP." Also, the 20 ppm THC level must be demonstrated at the outlet of an APCD.

The commenter concluded that there is no good way to control the emissions from their facility because the moisture and high airflow would create mechanical difficulties for all control technologies. We disagree with this assertion because high flow and high moisture exhaust streams ( e. g., 20 to 25 percent moisture at the outlet of a WESP) are treated by WESP/ RTO systems installed on OSB rotary dryers. 11 We also note that the moisture content shown in Table 2 1 above for the bake oven exhaust is higher than that for the press exhaust. We further disagree that wet/ wet hardboard press exhaust is problematic for a biofilter. Biofilters are particularly well suited to treat low temperature exhaust streams with a high moisture content.

The commenter dismissed the possibility of installing a biofilter by stating that a biofilter large enough to handle the exhaust from their two wet/ wet hardboard presses ( approximately 100,000 cfm each) has never been constructed or tested. To the contrary, we are aware of a biofilter in use at one PCWP facility that treats 600,000 cfm of exhaust. 12 In addition, the commenter also determined in their own cost analysis that a wet scrubber and biofilter combination would be the most cost effective control device option. That cost analysis was based on the assumption that a wet scrubber and biofilter combination would only achieve an 80 percent HAP reduction. Based on the data that we have collected, biofilters can easily achieve at least 90 percent control of HAP such as formaldehyde and methanol. If the commenter had reflected a 90 percent HAP control 2 53 efficiency in their cost analysis, then the cost effectiveness of the biofilter option would appear more favorable.

The commenter concluded that none of the control options they analyzed would be considered to be cost effective for a BACT determination and that the " best" control option for their facility would be no control. We note that BACT and MACT levels of control may differ and that the CAA does not allow us to consider cost as a criteria when determining the MACT floor.

The commenter pointed out that if we had separated hardboard presses or wet/ wet hardboard presses into their own subcategory, the MACT floor would be " no control" because only one hardboard press has incineration based control. This may be true for existing hardboard presses ( and for new and existing wet/ wet hardboard presses if they were placed in their own group), but it would not be true for new hardboard presses because MACT for new sources is based on the best performing similar source, and some hardboard presses are enclosed and controlled. The MACT floor analysis included three controlled hardboard presses ( the one mentioned by the commenter with incineration based control, plus two others with biofilters).

The CAA does not allow us to group equipment for the sole purpose of generating a MACT floor based on no emissions reduction ( unrelated to determining what emissions limitations the equipment used at sources are able to achieve). Even if wet/ wet hardboard presses were not controlled at the MACT floor, we would evaluate beyond the floor options. Because wet/ wet presses are some of the highest emitting presses in the PCWP industry, the costs of a beyond the floor control option would likely be equivalent to control costs for other press types and justifiable.

The commenter makes reference to the " highly competitive nature of the hardboard market." We note that hardboard is manufactured for the same markets and applications,

regardless of the manufacturing process, and that creating a subcategory that includes some hardboard presses and excludes others could change the competitive makeup of the hardboard market.

<IP_ADDRESS> Comment: Commenter IV D 57 requested that EPA consider including a " fundamentally different factors variance" in the final PCWP rule. The commenter explained that the NESHAP apply to all facilities within a category or subcategory, but occasionally there is one 2 54 facility that is different from all other facilities within a category. When that situation occurs,

EPA should provide a variance from the standards because that facility may be unable to achieve the standards. In this case, the commenter argued that their short cycle wet/ wet process hardboard press is fundamentally different from other wet/ wet process hardboard presses. The commenter stated that there is precedent and legal basis for providing this " fundamentally different factors variance" in the PCWP NESHAP, and excluding it would " constitute a fatal legal defect." The legal rationale for this variance was given as follows:

" The United States Supreme Court has recognized the necessity of a fundamentally different factors variance for nationwide, technology based limitations. In the context of reviewing Best Practicable Technology and Best Available Technology requirements of the Clean Water Act, the Supreme Court approved of uniform, technology based limitations, " so long as some allowance is made for variations in individual plants." E. I. du Pont de Nemours & Co. v. Train, 430 U. S. 112, 128 ( 1977). See also U. S. Steel Corp. v. Train, 556 F. 2d 822, 844 45 ( 7th Cir. 1977). In fact, with respect to effluent guidelines for the pulp and paper industry in particular, the D. C. Circuit held that " we cannot approve the regulations without finding that they include a sufficiently flexible variance provision." Weyerhaeuser Co. v. Costle, 590 F. 2d 1011, 1032 ( D. C. Cir. 1978). The D. C. Circuit explained that " t[ he] importance that the [ Supreme] Court assigned to a meaningful variance as a prerequisite to valid general limitations may be seen   in its use of the mandatory phrase ` so long as'." The courts have inferred the need for a " safety valve" variance even where, as in the case of the Best Practicable Technology requirements Federal Water Pollution Control Act of 1972, no variance was included in the statutory language. " As a result of these decisions, in 1979 EPA incorporated into its water pollution regulations an explicit fundamentally different factors (" FDF") variance, in 40 C. F. R. part 125, Subpart D. The Water Quality Act of 1987 subsequently incorporated an FDF variance into the Clean Water Act as section 301( n). For the same reasons, a uniform, technology based standard under Clean Air Act section 112 must be accompanied by some variance provision that would allow for different standards to be applied to facilities that are fundamentally different from those upon which the MACT standards are based. " The Supreme Court has acknowledged that variances " are appropriate to the regulatory process." Du Pont, 430 U. S. at 138 ( quoting the underlying Court of Appeals in E. I. du Pont de Nemours & Co. v. Train, 541 F. 2d 1018, 1028 ( 4th Cir. 1976); see also U. S. v. Allegheny Ludlum Steel Corp., 406 U. S. 742, 755 ( 1972). (" It is well established that an agency's authority to proceed in a complex area   by means of rules of general application entails a concomitant authority to provide exemption procedures in order to allow for special circumstances."). In explaining the need for a variance provision, the Fourth Circuit relied on the D. C. Circuit's reasoning that " a regulatory system which allows flexibility, and a lessening of firm proscriptions in a proper case, can lend strength to the system as a whole. The limited safety valve permits a more rigorous adherence to an effective regulation." Portland Cement Ass'n v. Ruckelshaus, 486 F. 2d 373, 399 ( D. C. 2 55 Cir. 1973) ( citations omitted), cert. denied 417 U. S. 921. The Fourth Circuit also cited to the D. C. Circuit's opinion in International Harvester v. Ruckelshaus: " Considerations of fairness will support comprehensive and firm, even drastic, regulations, provided a ` safety valve' is also provided." 478 F. 2d 615, 641 ( D. C. Cir. 1973)."

The commenter suggested that EPA follow the Supreme Court's reasoning and provide a fundamentally different factors variance as a " safety valve" for the PCWP NESHAP. This situation is an example of " how categorical MACT standards that are achievable and applicable to most facilities in a source category or subcategory can be unreasonably stringent and unachievable at a particular facility due to fundamental differences in its situation," and not including the variance could result in requirements that are unlawfully stringent.

Response: We disagree that it is necessary to include " fundamentally different factors variance" in the final PCWP rule. We are not aware of any facilities that would need such a " safety valve," including the wet/ wet hardboard facility that is the subject of this comment ( for the reasons set forth in response to comment <IP_ADDRESS> above). EPA has not included such variance provisions in MACT standards under section 112( d) of the CAA, as MACT standards are established to apply generally to categories and subcategories under section 112 ( d)( 1) and ( 2),

and are required to meet minimum stringency levels under section 112 ( d)( 3). Moreover, sections 112( i)( 1) and ( 3) impose compliance deadlines that apply to " any" new or reconstructed source and allow " no person" operating an existing source to violate a MACT standard. As a result,

CAA section 112 does not provide authority for the commenter's requested " variance" provision.

To maximize flexibility, the final PCWP rule includes three sets of compliance options ( six add on APCD compliance options, PBCOs, and emissions averaging) and many alternative methods for emissions testing and capture efficiency determination. In addition, to the extent any individual source demonstrates a need for more time to install controls to meet a MACT standard, section 112( i)( 3)( B) provides for specific extensions to be granted by permitting authorities, and section 112( i)( 4) allows the President to grant temporary exemptions to sources in cases where implementing technology is not available and the exemption is in the national security interests of the United States. Congress provided for no other type of " variance" from MACT.

<IP_ADDRESS> Comment: Commenter IV D 13 requested that further consideration be given to low temperature OSB strand conveyor dryers. The commenter stated that the current ( proposed) 2 56 definition of a strand dryer is not specific enough to determine if the low temperature OSB dryers fall under the general category of strand dryers, so a separate definition should be included for them in section 63.2292 ( What definitions apply to this subpart?). Also, since these conveyor strand dryers emit less HAP than rotary strand dryers and have been recognized as BACT in Minnesota, the commenter contended that they should be recognized accordingly and exempted from section 63.2240 ( What are the compliance options and operating requirements and how must I meet them?). The commenter noted that the 12 conveyor dryers used by their company have three drying zones, each with its own heating system and exhaust vent. When drying hardwoods, no VOC control is required; however, when drying pine, zones 1 and 2 are controlled. Zone 3 serves as a final conditioning zone and is exhausted to the atmosphere without need for VOC control. The commenter stated that preliminary HAP emission test data for drying southern yellow pine indicates that the strand dryer production based emission limit ( PBEL) may be achievable. The commenter suggested that EPA should either include work practice requirements for temperature control of low temperature OSB dryers or allow facilities operating these dryers to use a combination of PBELs and add on compliance options.

Response: The final rule does not allow use of an add on APCD to meet the PBCOs ( formerly known as PBELs), nor does the final rule allow combination of the PBCOs and add on compliance options ( e. g., PBCO for exhaust from one dryer zone and one of the six add on compliance options for the other two zones). The PBCO was developed for and applies to the entire process unit.

In light of the concerns expressed by the commenter, we reviewed our emissions data and MACT analysis for conveyor strand dryers. The MACT analysis we conducted at proposal treated conveyor strand dryers as a separate equipment group from rotary strand dryers. We noted that rotary strand dryers operate at much higher inlet temperatures ( often

900 ° F) than do conveyor dryers ( typically < 400 ° F), and rotary dryers provide greater agitation of the wood strands than do conveyor dryers. As a result, the emissions from conveyor dryers are lower than the emissions from rotary strand dryers. The emissions test data we have for conveyor dryers ( only formaldehyde and THC data are available) indicate that formaldehyde emissions from conveyor dryers are one to two orders of magnitude less than for rotary strand dryers. The THC emissions are also lower for conveyor dryers than for rotary dryers. Our MACT analysis for 2 57 conveyor dryers at proposal concluded that three of the eight conveyor dryers used in the United States operated with process incineration. Because there are fewer than 30 conveyor strand dryers, the MACT floor was based on the control level achieved by the third best controlled dryer. Thus, at proposal, we determined that the MACT floor control system for new and existing conveyor strand dryers was the emission reduction achievable with incineration based control. We included one definition of " strand dryers" in the proposed PCWP rule, since MACT for both rotary and conveyor strand dryers was represented by incineration based control.

As pointed out by the commenter, conveyor dryers have distinct zones with their own heating system and exhaust. We reviewed our MACT survey data and learned that all of the conveyor dryers in the United States have three zones. Upon further scrutiny of the MACT analysis at proposal, we learned that the three conveyor dryers that formed the basis for the MACT floor at proposal were routing the emissions from zone 1 only to an onsite combustion unit for incineration. The remaining five conveyor dryers have no HAP control ( four have an electrified filter bed; one routes 80 percent of the exhaust from each zone to a blend chamber,

which provides no HAP control, and directs the remaining 20 percent of the exhaust to the atmosphere). Thus, our conclusions regarding the MACT floor for conveyor dryers at proposal were overstated. Only zone 1 of the third best controlled conveyor dryer has incineration based control, as opposed to all zones. Therefore, we revised our analysis to reflect that the MACT floor for existing conveyor dryers is the emission reduction achieved with incineration based control on zone 1.

The commenter mentions operating 12 conveyor dryers. Six of these conveyor dryers are located at new plants that were not included in our pre proposal MACT floor analysis. These six conveyor dryers route emissions from zones 1 and 2 to a closed loop incineration system for emissions control. Given that newer facilities are incinerating conveyor dryer exhaust from zones 1 and 2, we determined that the MACT floor for new conveyor dryers is the emission reduction achieved with incineration based control for exhausts from zones 1 and 2.

Beyond the floor control options for existing conveyor dryers could include incinerationbased control on either zone 2, or zones 2 and 3, in addition to zone 1. A beyond the floor control option for new conveyor dryers could be incineration based control of zone 3 in addition to control of zones 1 and 2. To analyze these beyond the floor options, we assumed than on 2 58 RTO would be installed to control emissions from the additional zones because the combustion unit used to control emissions from zones 1 and/ or 2 may be unable to handle the exhaust from additional zones. 13 We determined that the environmental benefit of controlling additional conveyor dryer zones would not justify the cost for existing or new conveyor strand dryers.

<IP_ADDRESS> Comment: Commenter IV D 37 requested that the EPA divide continuous and batch presses into two different categories for the purpose of this rule. The commenter argued that control requirements in the rule were designed for batch presses, but continuous presses need a different set of capture and control criteria. The commenter provided information from environmental engineering firms on the fundamental differences between the two types of presses,

as well as information on continuous presses from suppliers. The commenter noted that continuous presses are much longer than batch presses, reaching lengths of 200 feet, which makes them difficult to completely enclose. The commenter was unaware of any continuous presses that have been Method 204 certified as having PTEs. They stated that operational problems with trying to enclose a continuous press include heat buildup leading to mechanical failures, impaired visibility leading to undetected problems that may cause unscheduled downtime, and an imbalance of heat on the press due to the extraction of air from the enclosure. The commenter further noted that safety concerns include the fire risk from the combination of heat accumulation and lubrication fluids, the possibility of unhealthy levels of HAP trapped in the enclosure, and the loss of mobility that could result if workers have to wear protective clothing. The commenter noted that the capital and operating costs of PTEs applied to continuous presses would exceed those associated with batch presses due to the large size of the enclosure and the increased maintenance costs resulting from heat build up within the enclosure. In addition, the commenter provided volatile organic emissions data for one of their continuous presses to demonstrate that emissions from the front stages are minimal and that the " overwhelming majority" of emissions are from the last 40 percent of the press length, referred to as the decompression zone. The commenter contended that gathering the emissions from all stages of the continuous press will result in a more dilute stream, which will be less cost effective to treat, and that the large volume of exhaust to be treated would likely preclude the use of biofilters, which are more practical for treating smaller volumes of air. In addition, because continuous presses have " multiple direct coupled emission extraction points," the use of the proposed tracer gas method of determining capture 2 59 efficiency would not be applicable ( the tracer gas method would only measure emissions not already captured by the multiple direct extraction points).

To remedy the situation, the commenter recommended that EPA divide batch and continuous presses into two different process unit groups for the purpose of determining the MACT floor. Because there are fewer than 30 continuous presses, the MACT floor for existing continuous presses would be determined based on the average emissions limitation achieved by the five best performing continuous presses. The commenter provided information to support their contention that none of the continuous presses achieved 100 percent capture, and suggested that the MACT floor for capture efficiency is 80 percent capture of emissions from the decompression stages. The commenter also stated that the proposed emission limitations in Table 1B of the proposed rule ( e. g., 90 percent reduction) should only apply to the captured emissions;

the commenter provided revisions to Table 1B that would incorporate their suggestion. Finally,

the commenter provided definitions of " reconstituted wood product batch press," " reconstituted wood product continuous press," and " decompression stage" that could be included in the final PCWP rule.

Response: The MACT floor determinations for PCWP equipment were based on process units that are similar with respect to design, operation, and emissions. We acknowledge that continuous presses have a different design than multi opening batch presses. However, based on the data available to us, continuous presses have emissions that are within the same range as those from batch presses on a lb/ MSF basis. Therefore, we believe it is reasonable to group batch and continuous together for purposes of determining the MACT floor. The MACT floor for continuous presses would be the same as the MACT floor for batch presses regardless of whether batch and continuous presses were placed in separate equipment groups. As explained below, we disagree that the MACT floor capture efficiency for continuous presses is 80 percent as suggested by the commenter.

The commenter was incorrect in suggesting that there are no continuous presses with Method 204 certified PTEs. On the contrary, the two existing press enclosures in the PCWP industry identified as being Method 204 certified surround continuous presses. These continuous presses are 41.5 ft and 110 ft long. Due to the presence of these presses in the industry, the MACT floor for new and existing continuous presses is a total enclosure and incineration based 2 60 control or biofilter regardless of whether or not batch and continuous presses are treated as separate equipment groups. In addition to the two presses with PTE mentioned above, there is a Method 204 certified PTE around a 181 ft long continuous press at a newer PCWP facility;

however, this press has had some operational problems associated with the PTE. It is not clear if the operational problems experienced by this 181 ft long press are the result of poor PTE design.

Long continuous presses are generally being installed at new PCWP facilities, as opposed to being retrofit at existing facilities. Given that there is at least one long continuous press ( 110 ft) with a Method 204 certified PTE that has not experienced operational problems associated with their press enclosure, we believe that wood products enclosures ( as defined in the final rule)

can be designed around long continuous presses. We recognize that higher cost may be associated with wood products enclosures around long continuous presses than for batch presses,

but the CAA does not allow us to consider cost at the MACT floor control level.

Enclosures greater then 200 ft in length are not unheard of. Such enclosures are common in the printing/ publishing industry. However, we do recognize there are differences in the enclosures used in the printing/ publishing industry and the PCWP industry. Although not cyclical in operation like batch presses, continuous presses are heated operations and may also have internal pressurization issues. 14 There have been operational problems associated with heat buildup inside the enclosure for the 181 ft long continuous press. Therefore, we believe it is appropriate for the same definition of " wood products enclosure" promulgated for batch presses to apply to long continuous presses as well ( as opposed to Method 204 certification). As discussed in more detail in section <IP_ADDRESS>, the definition of wood products enclosure included in the final PCWP rule is slightly different from the Method 204 PTE design criteria, and including this definition in the final PCWP rule eliminates the need for Method 204 certification of wood products enclosures. Enclosures meeting the definition of " wood products enclosure" in the final PCWP rule are assumed for all practical purposes to achieve 100 percent capture.

As an alternative to wood products enclosures, the final PCWP rule allows use of partial wood products enclosures. The capture efficiency of the partial wood products enclosure must be tested using either the tracer gas method included in Appendix A of the final PCWP rule, Methods 204 and 204A F, or an alternative method that is approved by the Administrator. We agree with the commenter that the tracer gas method would be inappropriate for some configurations of 2 61 partial wood products enclosures around long continuous presses ( e. g., if there are no sampling locations that can be used to distinguish between the HAP collected by the pick up/ extraction points and the HAP collected by exhaust fans in the general press area). However, the tracer gas method could be used for other press exhaust capture configurations ( e. g., for a partial enclosure covering the length of the press with exhaust ductwork that allows for separate sampling of the pick up/ extraction point exhaust and exhaust from inside the partial enclosure). In addition, the final rule includes Methods 204 and 204A F for testing of partial wood products enclosures whereby a Method 204 temporary total enclosure ( TTE) could be constructed around the press and a gas/ gas method such as Method 204D could be used to determine capture efficiency.

<IP_ADDRESS> Comment: Commenter IV D 04 asked for clarification of the definition of an engineered wood products ( EWP) press and stated that the EPA classification of certain presses as EWP presses may not always be valid. The commenter was aware of at least one facility in Minnesota that is a major source of HAP and that operates a press that could fit the definition of an EWP products press. The facility in question operates an LSL press that the commenter contended is very similar in operation to an OSB press. The commenter suggested that, instead of assuming that these presses have very small amounts of HAP, the emissions should be tested to ensure that there are no HAP before exempting these presses from emission control requirements through classification as EWP presses.

Response: Engineered wood product presses are not defined in the regulatory text of the PCWP NESHAP, but were mentioned in the preamble to the proposed rule. Engineered wood products presses include presses at LVL, PSL, LSL, glulam, and I joist plants. Plants manufacturing engineered wood products such as LVL, PSL, and LSL form and press ( often with microwave or radio frequency) billets that are much thicker than panels. Glulam plants use clamps to press laminated beams at room temperature. I joist plants do not use presses, but use curing chambers to cure the adhesive in the I joists. The emissions from EWP presses and curing devices are much lower then the total annual HAP emissions from most panel presses. Given the differences in design and annual HAP emissions, we treated EWP presses and panel presses separately for purposes of determining the MACT floor. Emissions from all of the EWP presses and curing devices in the PCWP industry are uncontrolled; therefore, the MACT floor for new and existing engineered wood product presses is no emission reduction. 3 2 62 The commenter questions whether LSL presses should be grouped with OSB presses.

The LSL and OSB manufacturing processes are somewhat similar in that whole logs are debarked and sliced into wood strands, and then the wood strands are dried using rotary or conveyor strand dryers. For purposes of determining the MACT floor for dryers, we included OSB and LSL rotary strand dryers in the same equipment group because these dryers are of the same design and have similar emissions. Similarly, we included conveyor strand dryers used to make OSB and LSL in the same equipment group. Following drying and resin application, LSL and OSB strands are formed into a mat that is inserted into the press. We differentiated among OSB and LSL presses for purposes of determining the MACT floor because of design differences and differences in the emissions from OSB and LSL presses. The presses used for LSL manufacture are singleopening presses, roughly 8 ft long and 4 ft wide ( 32 ft2 press area). 15 The LSL press compacts a thick mat of strands into a billet at can be up to 5.5 in thick. 2 Multi opening presses with 10 to 28 openings and an average pressing area of 166 ft2 per opening are most typically used for OSB manufacture; no single opening batch presses are used to make OSB. The OSB panels are pressed to an average thickness of 0.6 in. 10 Our MACT survey data indicate that the billet volume pressed annually in LSL presses ranges from 4.9 to 5.4 million ft3/ yr. 15 Our data show that OSB press throughput ranges from 172 to 380 MMSF 3/ 8" of panels per year ( equivalent to 5.4 to 12 million ft3/ yr). 10 In addition to having lower throughput, our data also indicate that LSL presses have lower emissions that OSB presses on a lb/ 1000 ft3 basis. Our data show that emissions of formaldehyde from an LSL press are two orders of magnitude less than the emissions from OSB presses. Given the design and size differences between LSL and OSB presses and the difference in emissions, we maintain that it would not be appropriate to group LSL presses with OSB presses ( and other reconstituted wood products presses).

2.3.2 Basis for MACT floor <IP_ADDRESS> Comment: Commenters IV D 27, IV D 21, and IV D 56 agreed that EPA properly followed section 112( d) of the CAA in establishing the PCWP MACT floor and supported the level of control chosen by EPA ( i. e., 90 percent control level for some PCWP process units and no reduction for others). According to the commenters, EPA correctly based the MACT floor on process units rather than entire facilities because of the available data and the nature of these facilities. Because pollution control techniques are not widely used throughout the 2 63 industry and the results are not universal, the MACT floor appropriately focuses on add on control techniques. According to the commenters, EPA correctly concluded that oxidizers and biofilters resulted in the best and most consistent emission control and used the 94th percentile to determine the best performing control device for each process unit group. The commenters stated that EPA's decision to group the data from all of the oxidizers and biofilters together in order to determine the MACT floor was appropriate given that the available data for some process unit groups were limited and not universally compatible. The commenters supported EPA's conclusion that the typical reduction in HAP emissions by oxidizers and biofilters was 90 percent, and that well maintained control devices generally only achieve less than 90 percent reduction if the inlet stream has a low HAP concentration. The commenters also supported the inclusion of concentration based limits at the outlet of the control device that similarly reflect this 90 percent removal efficiency. The commenters further stated that the MACT floor should not be set higher than 90 percent for two reasons. First, there are not enough data to support the conclusion that the control devices are regularly capable of achieving greater than 90 percent reduction. Second, regardless of how well an oxidizer is installed and maintained, the inlet concentration to the oxidizer is the factor that has the most effect on the reduction efficiency.

The commenters noted that " at high pollutant loadings, most oxidizers can easily achieve 90 percent removal, but at lower pollutant loadings, even the same well performing oxidizer will have a lower removal efficiency." The commenters asserted that the 90 percent removal levels were measured under " peak operating levels," so both the inlet HAP concentrations and the removal efficiencies were fairly high. The commenters noted that when EPA established a floor of 90 percent removal efficiency, it recognized that control devices will be able to achieve both higher and lower removal efficiencies. The commenters stated that requiring a removal efficiency higher than 90 percent would penalize sources that have low inlet pollutant concentrations.

"[ H] aving a low inlet concentration may show that the source was able to utilize pollution prevention techniques to minimize emissions, an activity which should be encouraged, not penalized."

In contrast to the previous three commenters, commenter IV D 11 disagreed with EPA's determination of an across the board MACT floor level of 90 percent control. Although the commenter supports EPA's use of the median of the top 12 percent of sources ( 94th percentile), 2 64 the commenter notes that the preamble does not state that the 90 percent reduction of THC,

formaldehyde, or methanol represents the 94th percentile. The commenter pointed out that the preamble does state that incineration based controls and biofilters showed THC, methanol, and formaldehyde emissions reductions " equal to or greater than 90 percent." The commenter further noted that the BID shows average emissions reduction data, not median, for THC,

methanol, and formaldehyde at 97 percent, 89 percent, and 95 percent, respectively. The commenter contended that this " one size fits all approach" of choosing a 90 percent reduction level is not appropriate, and EPA should reevaluate the 94th percentile for the individual compliance options for add on controls. The commenter agreed that concentration based compliance options were needed as an alternative to the percent reduction options for those sources with dilute emission streams. The commenter also recommended that EPA reserve the percent reduction options for those sources with more concentrated emissions streams by implementing a minimum inlet stack concentration level for sources meeting the percent reduction compliance options.

Response: To determine the MACT floor control level, we reviewed available data on pollution prevention techniques and the performance of add on control devices and identified those add on control systems that were best at reducing HAP emissions. We were unable to identify pollution prevention measures that can be universally applied across the industry, and we had no information on the degree of emissions reduction that can be achieved through pollution prevention measures. Therefore, our MACT analysis focused on the performance of add on control devices. Total hydrocarbon, formaldehyde, and methanol were considered in our analysis of control device performance because these three pollutants are the most prevalent pollutants emitted from the PCWP industry and represent the majority of the available data on control device performance. We concluded that only two types of add on APCDs consistently and continuously reduced HAP emissions: incineration based controls ( including RTOs, RCOs, and incineration of pollutants in onsite process combustion equipment) and biofilters ( used to control PCWP press emissions). The performance data for the incineration based controls and biofilters showed methanol and formaldehyde emissions reductions equal to or greater than 90 percent, except in those cases where the pollutant loadings of the emission stream entering the control systems were very low. The performance data for THC showed that incineration based control systems could 2 65 achieve THC emissions reductions equal to or greater than 90 percent. The average THC emissions reductions achieved with biofilters was about 80 percent. However, biofilters can achieve HAP emissions reductions equal to or greater than 90 percent. Both incineration based controls and biofilters can achieve identical formaldehyde and methanol emissions reductions.

We ranked the process units within each process unit group according to the HAP control devices that were applied. For process unit groups with at least 30 sources, we based the MACT floor on the emission level achieved by the process unit and its control system that is at the bottom of the top 6 percent of the best performing process units ( i. e., the 94th percentile). For those process unit groups where there were fewer than 30 but at least five process units, the emission level achieved by the process unit and its control system that is the median of the best performing five sources ( i. e., the " number 3" source) represents the MACT floor level of control. When a process unit group had fewer than five process units, we determined the appropriate control technology based on the control technology used by the majority of the process units in the process unit group.

When we ranked the process units, we treated process units equipped with any type of incineration based control system or biofilters as being equivalent with respect to their potential to reduce HAP emissions. We ranked the process units by control device rather than actual unit specific emissions reductions because we have limited inlet/ outlet data on which to calculate control efficiency. We are not aware of any significant design or operational differences among control systems or factors other than the type of control system used that would affect the ranking of process units. For example, there are approximately 303 softwood veneer dryers nationwide,

and HAP emissions from approximately 64 of these dryers ( 21 percent nationwide) are controlled using incineration based control systems. The HAP emissions from the remainder of the softwood veneer dryers are uncontrolled. In this example, the 94th percentile is represented by the control system applied to the softwood veneer dryer ranked at number 18 ( 18/ 303 = 6 percent),

which is an incineration based control system. We only have control efficiency data for nine veneer dryers. Data are not available for the 18th ranked dryer. In order to associate a control efficiency with the 18th ranked dryer, it was necessary to conclude that the control efficiency achieved by the incineration based controls for which we had data also represented the control efficiency of the 18th ranked veneer dryer. For the reasons discussed in the paragraphs below, we 2 66 believe this conclusion regarding the performance of APCDs is very appropriate for incinerationbased controls and biofilters used to control PCWP process units. As in the softwood veneer dryer example, we were able to identify the APCD but were unable to associate a specific control efficiency with the 94th percentile unit ( or number 3 unit for process groups of less than 5 sources)

for most of the PCWP process unit groups because control efficiency data were generally unavailable for the 94th percentile ( or number 3) ranked unit. Thus, ranking process units based on actual emissions reduction as suggested by commenter IV D 11 is not possible. We believe that ranking process units based on actual emissions reduction ( as opposed to ranking by APCD type) is unnecessary for the PCWP source category for the reasons described below.

For the purpose of establishing the performance level of the MACT floor control systems,

we decided to group all of the available data on incineration based controls and biofilters together. When we reviewed the available data, we found that the data do not show any correlation between the types of process units controlled ( e. g., rotary dryers vs. presses) and the performance of the HAP control systems. That is, the HAP control systems can achieve the same level of control ( e. g., outlet concentration, percent reduction) regardless of the type of process unit controlled. Some of the control systems treat HAP emissions from multiple types of process units, such as tube dryers, reconstituted panel presses, and board coolers. In those cases, separate determinations of the performance of the control system on emissions from each type of process unit were not possible. Also, limited or no inlet/ outlet data were available for the control systems applied to the process units in some groups. Also, in some cases, it was not possible to directly compare the performance of different control systems because data were not available for the same pollutant. For example, for one RTO, we might only have THC emissions data, and for another RTO, we might only have formaldehyde data. Our ability to compare the performance of the different types of incineration based control systems with each other and with biofilters was also hampered by variability in uncontrolled emissions being treated by the different control systems. For example, the available THC concentration data for the inlet of the control systems ranged from as low as 45 ppmvd to as high as 5,100 ppmvd. With the exception of some control systems with lower pollutant inlet concentrations, the available data for incineration based controls and biofilters show that these control systems can achieve THC, methanol, or formaldehyde emissions reductions greater than or equal to 90 percent. 2 67 To account for the variability in the type and amount of HAP in the uncontrolled emissions from the various process units and the effect of this variability on control system performance, we decided to base the MACT floor performance level on all three of the pollutants we analyzed and include maximum concentration levels in the outlet of the control systems as an alternative to emissions reductions. The MACT floor performance level is a 90 percent reduction in THC or methanol or formaldehyde emissions. The maximum concentration level in the outlet of the MACT floor control system is 20 ppmvd for THC, 1 ppmvd for methanol, or 1 ppmvd for formaldehyde. We chose 20 ppmvd as the alternative maximum concentration for THC because 20 ppmvd represents the practical limit of control for THC. We chose 1 ppmvd as the maximum outlet concentration for both methanol and formaldehyde because this concentration is achievable by MACT control systems and the method detection limits for these compounds using the NCASI impinger/ canister method ( NCASI Method IM/ CAN/ WP 99.01, proposed to be incorporated by reference in today's proposed rule) are less than 1 ppmvd.

We acknowledge that some incineration based controls and biofilters achieve greater than 90 percent reduction in formaldehyde, methanol, or THC. However, we also recognize that the percent reduction achieved varies according to pollutant inlet concentration, as the commenters have stated. Other unknown factors may also cause variability in control system performance. In addition, there is variability related to emission measurements. For example, we have THC percent reduction data for an RTO used to control emissions from three tube dryers and a press at an MDF plant for two emission tests conducted at different times. In 1996, the RTO achieved 92.7 percent reduction of THC, and in 1998 the same RTO achieved 98.9 percent reduction of THC. In addition, we have emissions test data for the same process unit and control system for multiple years, and these data show different emission factors, indicating that variability is inherent within each process unit and control system combination. We disagree with commenter IV D 11 that a minimum inlet stack concentration is needed for sources meeting the percent reduction compliance options because sources with low inlet concentrations generally would have more difficulty meeting the 90 percent reduction requirement.

<IP_ADDRESS> Comment: Commenters IV D 27, IV D 27, IV D 21, and IV D 56 concurred with the no emissions reduction MACT floor determinations made for certain process units,

including existing fiberboard mat dryers, existing press pre dryers, and existing reconstituted 2 68 wood product board coolers. The commenters stated that the method EPA used to come to that conclusion is proper under the CAA; Cement Kiln Recycling Coalition v. EPA, 255 F. 3d 855 ( D. C. Cir. 2001); and National Lime Association v. EPA, 233 F. 3d 625 ( D. C. Cir. 2000). First,

the MACT floor is appropriately set based on emissions reductions achieved by the bestperforming sources, rather than on emissions data alone, and is consistent with section 112( d) of the CAA. The commenters cited two provisions of the CAA and language from a D. C. Circuit ruling that support that point. Second, EPA identified the best performing process units and determined that neither the average of the best performing 12 percent of sources nor the one bestperforming source was achieving emissions reduction through the use of an emissions control system. Therefore, the MACT floor was set at no emissions reduction for both existing and new sources. The commenters noted that § 112( d)( 3)( A) of the CAA clearly states that the maximum degree of reduction for existing sources of HAP emissions shall not be less stringent than " the average emission limitation achieved by the best performing 12 percent of the existing sources ( for which the Administrator has emissions information)[.]" The commenters asserted that,

although pollution prevention techniques are used at some facilities, they do not achieve consistent results and cannot be included in the MACT floor. Because the median best controlled source did not use control technology and because EPA has identified no other universally applicable variable that certain PCWP process units can employ to reduce HAP emissions, the commenters contended that EPA properly set the MACT floor at no emissions reduction. The commenters also noted that EPA's request for comment on the MACT floor for miscellaneous coating operations and wastewater operations included concern about insufficient data, but the commenters agreed that the floor is " no control," and that this accurately reflects current PCWP facility practices.

The commenters further noted that EPA properly addressed the concerns noted by the D. C. Circuit in Cement Kiln Recycling Coalition v. EPA, 255 F. 3d 855 ( D. C. Cir. 2001) ( Cement Kiln) and National Lime Association v. EPA, 233 F. 3d 625 ( D. C. Cir. 2000) ( National Lime).

According to the commenters, in Cement Kiln, EPA identified the median of the best performing 12 percent of sources and set the MACT floor at the worst emission level achieved by any source using the same emission control technology that was used by most of the top 12 percent. The D. C. Circuit ruled that this MACT floor was not a valid estimate of the performance of the best 2 69 performing sources in practice. EPA assumed that control technology was the only way to reduce HAP emissions, but other factors were influencing the reduction as well. Some of those factors could have been inadequate maintenance or inferior operating practices, in which case the worstperforming sources would certainly not be an estimate of the best performing sources under the most adverse conditions. The court noted that if EPA could demonstrate that MACT technology significantly controlled emissions, and that factors other than the control had a negligible effect,

the MACT approach could be a reasonable means of satisfying the statute's requirements. The commenters noted that, in developing the PCWP rule, EPA again followed the MACT approach,

determining that the average of the best performing 12 percent of certain existing PCWP process units did not reflect the use of any control technology. EPA further determined that no other universally applicable variables would affect HAP emissions, a determination it did not make in Cement Kiln. For the PCWP process units for which the MACT floor is 90 percent, EPA again determined that there are no other factors that significantly impact the removal efficiencies of the add on controls. For these reasons, the commenters contended that EPA corrected the mistakes made in the Cement Kiln situation when developing the PCWP MACT.

The commenters noted that in National Lime, EPA followed a similar MACT approach to Cement Kiln, but it had insufficient data for some HAP. If EPA found an insufficient number of plants in its database controlling a particular HAP with pollution control technology, it determined that the emission floor was " no control." The D. C. Circuit ruled that if EPA did not consider alternative pollution reducing measures, it could not decline to set emissions standards on the grounds that the best performing sources did not use control technology.

" The technologies, practices or strategies which are to be considered in setting emission standards under this subsection go beyond the traditional end of the stack treatment or abatement system. The Administrator is to give priority to technologies or strategies which reduce the amount of pollution generated through process changes or the substitution of materials less hazardous. Pollution prevention is to be the preferred strategy wherever possible." ( S. Rep. No. 101 228, 168 ( 1989)) ( emphasis added).

The commenters stated that the D. C. Circuit ruling in National Lime does not prevent EPA from setting a MACT floor of no emissions reductions, it simply means that EPA must examine all methods of removing HAP before setting a floor. According to the commenters, in developing the PCWP rule, EPA did look at pollution prevention measures and other approaches to determining the MACT floor, but found none that are universally applicable to reduce HAP 2 70 emissions. Therefore, the commenters contended that EPA is permitted by statute to set the MACT floor for existing sources at any level not less stringent than the average limitation achieved by the best performing 12 percent, even if that floor level reflects no reduction in emissions.

Commenter IV D 26 disagreed with the four previous commenters and stated that not establishing emission reduction limits for operations like miscellaneous coating and wastewater is unlawful. The commenter argued that EPA should not make its MACT floor decisions based on " insufficient information" and the fact that there is no current control in place. The commenter stated that, according to National Lime Ass'n v. EPA, 233 F. 3d 625, 633 634 ( D. C. Cir. 2000),

EPA cannot set a MACT floor of " no control" because it believes that a pollutant is not controlled by any particular technology. The commenter stated that EPA failed to explain why insufficient data are available and what additional steps could be taken to obtain the necessary data. For these reasons, the commenter stated that EPA's proposed MACT floor levels of " no control" are " unlawful, arbitrary, and capricious."

Response: For those process units not required to meet the control requirements in the final PCWP rule, we determined that ( 1) the MACT floor level of control is no emissions reductions and beyond the floor control options are too costly to be feasible; or ( 2) insufficient information is available to conclude that the MACT floor level of control is represented by any emissions reductions ( miscellaneous coating operations and wastewater operations). We based our MACT floor determinations for PCWP emission sources on the presence or absence of an add on APCD because we are not aware of any demonstrated pollution prevention techniques that can be universally applied across the industry, and we have no information on the degree of emissions reduction that can be achieved through pollution prevention measures. Therefore, to our knowledge, the use of add on APCD is the only way in which PCWP sources can currently limit HAP emissions, and the only way to identify the MACT floor for these sources is to identify a level that corresponds to that achieved by the use of add on APCD. When determining the MACT floor, we ranked the process units by control device rather than by actual unit specific emissions reductions because we have limited inlet/ outlet data ( i. e., inlet/ outlet data are not available for every controlled process unit) on which to calculate control efficiency ( see also the response to comment No. <IP_ADDRESS> above). Based on the available information, we are not aware 2 71 of any significant design or operational differences among each type of control system evaluated that would affect the ranking of process units. Furthermore, we are not aware of factors other than the type of control system used that would significantly affect the ranking of process units.

An analysis of the available emissions data does not reveal any process variables that can be manipulated ( without altering the product) to achieve a quantifiable reduction in emissions. 13 Ranking process units according to control device, we determined that the MACT floor is no emissions reductions for several PCWP process unit groups, including press pre dryers,

fiberboard mat dryers, and board coolers at existing affected sources; and dry rotary dryers,

veneer re dryers, plywood presses, EWP presses, hardwood veneer dryers, humidifiers,

atmospheric refiners, formers, blenders, rotary agricultural fiber dryers, agricultural fiber board presses, sanders, saws, fiber washers, chippers, log vats, lumber kilns, storage tanks, wastewater operations, miscellaneous coating operations, and stand alone digesters at new and existing affected sources. We also determined that beyond the floor control options are too costly for these process unit groups. 13 For miscellaneous coating operations and wastewater operations, we determined at proposal that we had insufficient information to conclude that the MACT floor level of control is represented by any emissions reductions. In the preamble to the proposed rule, we requested comment on whether a MACT floor of no emissions reductions for miscellaneous coating operations and for wastewater operations was appropriate, and we requested information on HAP or VOC emissions from miscellaneous coatings and wastewater operations. We received no comments containing additional information on emission reduction measures or HAP/ VOC emissions from miscellaneous coatings and wastewater operations. Following proposal, we reviewed our MACT analyses for miscellaneous coating and wastewater operations. We have no more reason to believe now than we did at proposal that PCWP wastewater operations are in fact subject to any emission control measures. For miscellaneous coating operations, we gathered some additional information and were able to revise our conclusions regarding the MACT floor in the absence of specific information on the emissions reduction achieved.

Prior to proposal, insufficient information was available for miscellaneous coating operations because we did not gather information on measures used to reduce emissions from these operations. Insufficient information was available for wastewater operations because the 2 72 PCWP survey responses we received were not very informative. Potential HAP emissions from miscellaneous coating and wastewater operations are believed to be minuscule compared to the emissions from PCWP process units such as presses or dryers, and these operations have not been the focus of permit requirements or consent decree actions. Therefore, our PCWP general survey ( which was sent to softwood plywood and reconstituted wood products plants) did not gather the same level of detailed information on miscellaneous coating or wastewater operations as for other PCWP process units.

Our PCWP general survey asked questions regarding the use of miscellaneous coating operations because industry trade association representatives had notified us of some minor ancillary processes performed at PCWP facilities that had the potential to be considered finishing processes under the Wood Building Products NESHAP. The industry representatives requested that we consider these processes under the PCWP rule to avoid the potential for PCWP facilities to be subjected to dual coverage under two NESHAP for processes associated with PCWP manufacturing. The intent of the questions related to miscellaneous coating operations in the PCWP survey was to gather information so we could determine the extent to which these processes are being used at facilities covered under the PCWP NESHAP and to gauge whether these processes should be considered under the PCWP NESHAP or the Wood Building Products NESHAP. The PCWP general survey requested that facilities provide information on the types of materials used in these processes, as well as the annual quantities of the materials used. 10 The survey did not request information on potential emissions from these operations or methods for reducing emissions from these miscellaneous processes. Prior to proposal, we noted that if there were HAP emissions from miscellaneous coating operations, then one control strategy to reduce emissions would be a reduction in the amount of HAP contained in the coatings rather than application of an emissions capture and control system. However, we concluded that the MACT floor for miscellaneous coating operations was no emissions reduction in the absence of specific information on potential emission reductions achievable through product substitution. We revisited our MACT analysis for miscellaneous coating operations following proposal. Based on the available information, we have no basis to conclude that the MACT floor for new or existing sources is represented by any emission reduction for several miscellaneous coating processes ( i. e.,

anti skid coatings, primers, wood patches applied to plywood, concrete forming oil, veneer 2 73 composing, and fire retardants applied during forming), and we determined that there are no costeffective beyond the floor measures to reduce HAP from these coating processes. However,

some facilities reported use of water based ( non HAP) coatings in their PCWP survey responses for other types of coatings ( including edge seals, nail lines, logo paint, shelving edge fillers, and trademark/ gradestamp inks). Other facilities reported use of " solvent based" coatings for these processes. In a few instances, respondents provided information on the percent HAP content of a solvent based coating. Solvent based coatings do not always contain HAP ( e. g., the solvent may be mineral oil, which does not contain HAP). Water based coatings typically do not contain HAP. Thus, the water based and some of the solvent based coatings reported in the responses to the PCWP survey are " non HAP" coatings. While the emission reduction that will be achieved as a result of these coating substitutions cannot be determined, it is clear that use of non HAP coating represents the MACT floor because of the large number of facilities reporting use of non

HAP coatings. Beyond the floor options were not considered for edge seals, nail lines, logo paint, shelving edge fillers, and trademark/ gradestamp inks because no further emissions reductions can be achieved through methods other than use of non HAP coatings. Based upon our revised MACT analysis, the final PCWP rule requires use of " non HAP coating" for processes identified as " Group 1 miscellaneous coating processes," where:

Non HAP coating means a coating with HAP contents below 0.1 percent by mass for OSHA defined carcinogens as specified in 29 CFR 1910.1200( d)( 4), and below 1.0 percent by mass for other HAP compounds.

Group 1 miscellaneous coating operations means application of edge seals, nail lines, logo ( or other information) paint, shelving edge fillers, trademark/ gradestamp inks, and wood putty patches to plywood and composite wood products ( except kiln dried lumber) on the same site where the plywood and composite wood products are manufactured. Group 1 miscellaneous coating operations also include application of synthetic patches to plywood at new affected sources.

The definition of non HAP coating was based on the description of non HAP coatings in the final Wood Building Products NESHAP ( subpart QQQQ). This definition allows for unavoidable trace amounts of HAP that may be contained in the raw materials used to produce certain coatings.

Kiln dried lumber is excluded from the requirement to use non HAP coatings because application of coatings used at kiln dried lumber manufacturing facilities is not part of the PCWP source category. Although trademarks/ gradestamps are applied to kiln dried lumber, lumber kilns are the 2 74 only processes at kiln dried lumber manufacturing facilities covered under the PCWP source category.

Our PCWP general survey asked questions regarding process water and wastewater generation and wastewater treatment operations at each plant site. The purpose of these questions was to gather information on the quantity, sources, and treatment of process water and wastewater at the plant and to determine the potential for HAP emissions from the water.

Another reason for gathering the process water and wastewater information was for use in assessing the potential impacts ( and disposal costs) of requiring add on APCDs that may create new sources of wastewater. 10 Our PCWP survey requested information on annual wastewater flow rate, HAP content of the wastewater, and how the wastewater is handled and treated. The responses relating to wastewater operations were difficult to interpret. From the survey responses, we learned that wastewater operations such as lagoons, log vats, clarifiers, and settling ponds are used at PCWP plants to manage wastewaters because most PCWP plants are not allowed to discharge wastewaters. Wastewater sources at PCWP plants include hardboard process water, various wash waters ( e. g., from washing of the glue line, blender, dryers, RTO),

control device recirculated and blowdown water, and condensates. Information on wastewater flow was provided in the nonconfidential PCWP survey responses for 241 wastewater operations.

( An additional 92 wastewater operations were reported, but no flow rates were provided.)

However, HAP concentration data were provided for only 23 of the 241 wastewater operations for which flow rates were provided. When comparing the flow rates and concentrations provided for these 23 wastewater operations to the applicability criteria for the Hazardous Organics NESHAP ( HON) wastewater provisions ( 40 CFR 63, subpart G), it was determined that only two of the operations could emit HAP concentrations high enough to trigger control requirements under the HON. The highest reported concentration would result in only 0.31 tpy of methanol emitted from the wastewater stream. The results from sampling of water streams performed by the NCASI show some water streams with methanol concentrations higher than those reported in the PCWP survey responses. However, no information on the flow rate is available to use in calculating potential emissions from the wastewater operations tested by NCASI, and the samples collected from the wastewater streams may not be representative of the water contained in settling ponds, lagoons, etc., which can be diluted with stormwater. Potential control methods for 2 75 wastewater operations include handling of the wastewater in order to minimize emissions ( e. g.,

through hard piping or a closed system), use of activated sludge biological treatment systems, or use of closed vent systems and control devices. We are not aware of any PCWP facilities that currently employ these techniques to control air emissions from wastewater operations. We have no data to suggest that HAP emissions from wastewater operations are the subject of control measures that could correspond to an identifiable numerical emission level or reduction rate.

Therefore, based on the available information, the MACT floor for new and existing wastewater operations at PCWP facilities was determined to be no emission reduction. Furthermore, given that our best data show that the emissions from wastewater operations are less than 1 tpy, we concluded that application of the control measures mentioned above would not be cost effective beyond the floor options. 13 There are 115 wastewater storage tanks listed in the nonconfidential responses to the PCWP survey. The HON requires that certain wastewater storage tanks have a fixed roof and requires that other tanks ( containing liquid with higher vapor pressures) use a fixed roof and closed vent system that routes vapors to a control device, use a fixed roof and an internal floating roof, or use an external floating roof. We expect that PCWP wastewater storage tanks would meet the HON applicability for tanks required to have a fixed roof, and we expect that most PCWP tanks already have a fixed roof. Use of a fixed roof does not reduce emissions unless coupled with a control device. Therefore, based on the available information, we determined the MACT floor for new and existing wastewater storage tanks at PCWP facilities to be no emission reduction. Based on our analysis of beyond the floor control measures for resin tanks, we also concluded that beyond the floor control measures for wastewater tanks are not cost effective.

The CAA does not require us to look further; we based our MACT floor analyses on the best data available to us. However, if we had decided to collect more data, we could have resurveyed facilities to ask them specifically about HAP emissions from their wastewater operations and to ask the facilities if they are taking any steps to reduce HAP emissions from these operations. However, we do not know if better or additional information could be obtained from another survey. The fact that we did not get useful information on wastewater HAP in our first PCWP survey suggests that potential HAP from wastewater operations is not something facilities have been required to track for permitting purposes. Re surveying facilities would be time 2 76 consuming and burdensome to facilities. Unlike dryers and presses at PCWP plants, wastewater operations have not been treated by permitting authorities as being significant sources of HAP emissions. We expended much effort in the early stages of the project gathering complete and accurate information on the PCWP processes with the most potential for HAP emissions and the greatest potential for emission control ( i. e., the processes that have been the focus of permit requirements limiting HAP/ VOC emissions). Had we believed that there were emissions control measures associated with wastewater operations, we would have gathered more information for these processes earlier in the project. In response to the commenter's objection to the incompleteness of the data set for wastewater operations, we note that the D. C. Circuit does not require EPA to obtain complete data as long as we are able to otherwise estimate the MACT floor. Sierra Club v. EPA, 167 F. 3rd 658, 662 ( D. C. Cir. 1999).

<IP_ADDRESS> Comment: Commenter IV D 26 pointed out that setting control standards for only six HAP is unlawful. The commenter asserted that, according to the CAA and National Lime Ass'n v. EPA, 233 F. 3d 625, 633 634 ( D. C. Cir. 2000), EPA is required to set standards for every HAP listed in 112( b)( 1) emitted by PCWP operations, not just the ones that are the easiest to measure. The commenter noted that EPA stated in the proposal preamble that PCWP facilities emit many different HAP, including metals and carcinogens like benzene and chloroform. The commenter stated that EPA's decision not to regulate certain HAP because they are emitted " in low quantities that may be difficult to measure" is arbitrary, and EPA's choice of wording implies that EPA does not know whether or not these HAP are difficult to measure. The commenter also noted that EPA provided no legal basis for this decision.

Commenter IV D 33 stated that EPA provided inadequate information on the selection of HAP of concern from PCWP sources, which was based on mass of emissions only. For example,

the proposal does not provide information on why the HAP selected for regulation include six out of at least 12 HAP emitted from PCWP sources and exclude benzene, carbon tetrachloride,

chloroform, and metals, including manganese compounds.

Commenter IV D 27 disagreed and noted that a requirement that EPA impose an emissions standard for every listed HAP, without regard to whether or not there are applicable methods for reducing HAP emissions or whether the MACT floor sources actually use such 2 77 method, contradicts the plain language of the statute. Commenter IV D 27 contended that the statute specifically frames the inquiry in terms of degrees of reduction.

Response: The final PCWP rule contains numerical emission limits in terms of methanol,

formaldehyde, THC, or " total HAP" ( which is defined in the final rule as the sum of the six HAP acrolein, acetaldehyde, formaldehyde, methanol, phenol, and propionaldehyde). In the proposal preamble, we noted that other HAP are sometimes emitted and controlled along with these six HAP, but in low quantities that may be difficult to measure. Benzene, chloroform, and other HAP have been detected in emissions from some process units in the PCWP industry. We estimate that the nationwide emissions of these HAP from the PCWP industry are 44 tpy of benzene and less than 1.6 tpy of chloroform ( 0.2 percent and 0.008 percent of the nationwide baseline HAP emissions from the PCWP source category, respectively). Eighty seven percent of the benzene emission test runs ( over 600 runs) in our emissions data base for uncontrolled process units were below the test method detection limit. Chloroform was detected at only one type of process unit ( green furnish rotary particle dryers). Similarly, HAP other than the six HAP comprising " total HAP" often are not detected in uncontrolled emissions from process units; if detected, they are emitted in very low mass ( e. g., less than 100 tpy nationwide) compared to the emissions of " total HAP." The nationwide emissions of " total HAP" are 18,190 tpy, which is 96 percent of the nationwide emissions of all HAP ( 19,000 tpy). The six HAP that comprise " total HAP" are found in emissions from all PCWP product sectors that contain major sources and in emissions from most process units.

At proposal, when we stated that certain HAP are emitted " in low quantities that may be difficult to measure," we were referring to HAP that are often emitted at levels below test method detection limits. We disagree with the suggestion by commenter IV D 26 that we do not know whether or not these HAP are difficult to measure. Our data clearly show that these HAP are difficult or impossible to measure because they are emitted in very low quantities. Such low quantities are not detectable by the applicable emission testing procedures ( which are sensitive enough to detect HAP at concentrations below 1 ppm). As in the examples of benzene and chloroform above, many of the HAP other than those included in " total HAP" were detected in less than 15 percent of test runs, or for only one type of process unit. 2 78 Based on our emissions data, we determined that methanol, formaldehyde, THC, or " total HAP" are appropriate surrogates for measuring all HAP emitted by the PCWP source category.

The PBCO and emissions averaging compliance options in the final PCWP rule are based on " total HAP." Review of the emission factors used to develop the emissions estimates for the PCWP source category indicates that uncontrolled emissions of HAP ( other than the six HAP) are always lower than emissions of the six HAP for every process unit with MACT control requirements. Thus, process units meeting the PBCO based on total HAP also would have low emissions of other HAP. The emissions averaging provisions and add on control device compliance options involve use of add on APCD. The available data show that a reduction in one predominant HAP ( or THC) correlates with a reduction in other HAP if the other HAP are present in detectable quantities and at sufficient concentration. The data show that the mechanisms in RTO, RCO, and biofilter control devices that reduce emissions of formaldehyde and methanol also reduce emissions of the remaining organic HAP. In addition, an analysis of the physical properties of the organic HAP emitted from PCWP processes indicates that nearly all of the HAP would be combusted at normal thermal oxidizer operating temperatures. The available emissions data do not reveal any process variables that could be manipulated ( without altering the product) to achieve a quantifiable reduction in emissions. Furthermore, nothing in the data suggests that process variables could be manipulated in a way that would alter the relationship between formaldehyde and methanol reduction and reduction of other HAP. 16 We determined that it is appropriate for the final PCWP rule to contain compliance options in terms of " total HAP," THC, formaldehyde, or methanol because the same measures used to reduce emissions of these pollutants also reduce emissions of other organic HAP.

With regard to metal HAP, the preamble to the proposed rule mentioned the potential for metal HAP emissions when discussing risk based options. The PCWP industry uses combustion to provide process heat to direct fired processes ( in which the combustion gases mix with process gases). We are aware that combustion of certain fuels can result in metal HAP emissions, and that certain metal HAP are relatively potent. Thus, metal HAP emissions were estimated for direct fired PCWP process units for purposes of conducting a conservative risk screening analysis for the PCWP source category. However, we have no industry specific emissions test data to verify that there are indeed metal HAP emissions from direct fired PCWP process units. Our 2 79 PCWP survey requested information on emissions of all HAP. Approximately 100 emissions test reports containing HAP data were submitted with the responses to the PCWP survey. However,

no emissions test data for metal HAP were received. In the absence of industry specific data, and for the purposes of developing a conservative risk screening analysis, trace element emission factors from AP 42 section 1.6 ( Wood Residue Combustion in Boilers) were used to estimate metal HAP emissions from the PCWP industry. There are differences in the types of combustion units used in PCWP processes ( e. g., suspension burners) and wood residue fired boilers. 17 All of the emission tests referenced in developing the AP 42 trace element emission factors were boilers as opposed to suspension burners. While use of the AP 42 emission factors may have been appropriate for purposes of developing an estimate of metal HAP emissions, it would not be appropriate to use these same emission factors for purposes of establishing numerical emission limits for PCWP processes. We further note that we did not request particulate matter ( PM)

emissions data in our PCWP survey. Thus, we have neither the metal HAP data nor the PM data necessary to demonstrate that PM is an appropriate surrogate for metal HAP for the PCWP source category or to establish a PM emissions limit.

<IP_ADDRESS> Comment: Commenter IV D 30 stated that the EPA followed the CAA Amendments of 1990 well in defining the source category and affected source, setting the MACT standard, determining the best industrial practices, and considering health, environmental, and cost requirements. However, the commenter contended that although EPA analyzed the risks to children per Executive Order 13045, it could have done a better job of assessing risks to other groups and residual risks in general.

Response: Section 112 of the CAA requires that we establish NESHAP for the control of HAP from both new and existing major sources. The CAA requires the NESHAP to reflect the maximum degree of reduction in emissions of HAP that is achievable. This level of control is commonly referred to as the MACT. Thus, MACT standards are technology based, not riskbased Section 112( f)( 2) of the CAA requires us to examine the post MACT standard risk ( residual risk) within eight years after promulgation of the MACT standard to ensure that the standards provide an ample margin of safety to protect public health. Therefore, the residual risk posed by PCWP facilities after MACT controls are implemented will be assessed at a later date.

If the MACT standards "... do not reduce lifetime excess cancer risk to the individual most 2 80 exposed to the emissions... to less than one in a million," then we will consider further measures to reduce the risk to acceptable levels.

<IP_ADDRESS> Comment: Commenter IV D 14 argued in favor of a MACT floor of " no control"

for small and medium sized plywood and particleboard mills. The commenter contended that the existing MACT floor was set by larger mills with controlled softwood veneer dryers and controlled particleboard presses, which is not reflective of smaller facilities. The commenter believes that two of its mills ( one plywood mill and one particleboard mill) will be forced to shut down if the proposed rule is promulgated without changes. The commenter pointed to the high cost of compliance and minimal health risks posed by these facilities as justification for setting the MACT floor at " no control" for small and medium sized plywood and particleboard mills.

Response: We did not distinguish between facility size or total facility production for purposes of determining the MACT floor. We applied the MACT floor methodology at the process unit level rather than the facility level for several reasons: ( 1) this is how controls are installed at PCWP facilities ( i. e., controls are installed on process units, rather than on all emission sources at a facility); ( 2) we had more accurate and complete information for process unit emissions and emissions reductions than for facility wide emissions and emissions reductions; and ( 3) applying the MACT floor methodology at the facility level would have produced ambiguous results when some of the equipment ( e. g., dryers) at a facility were controlled and other equipment ( e. g., the press) remained uncontrolled. In most cases, there are no design differences in PCWP process units used at high production plants versus low production plants. It was not necessary for us to consider plant production when evaluating which process units had similar design or operation. We would like to point out that we distinguished among particleboard extruders and press molds ( used by smaller particleboard plants), and particleboard panel presses ( used by larger particleboard plants) based on differences in equipment design. We also distinguished among dry and green rotary particle dryers because of different emissions characteristics. In addition, we distinguished among plywood presses and reconstituted wood products presses due to differences in emissions and design ( e. g., plywood presses commonly do not have a loader or unloader like reconstituted wood products presses). These equipment distinctions were made for technical reasons ( i. e., based on differing emissions characteristics or equipment design). We do not believe there are technical reasons for distinguishing among 2 81 facilities ( or equipment at those facilities) according to facility production. The CAA does not allow us to consider costs when determining the MACT floor control level or to subcategorize by cost.

The final PCWP rule applies only to facilities that are major sources of HAP emissions;

therefore, smaller facilities that are area sources are exempt from the rule. Major sources of HAP are those stationary sources or groups of stationary sources that are located within a contiguous area under common control that emit or have the potential to emit, considering controls, 9.07 Mg/ yr ( 10 tpy) or more of any one HAP or 22.68 Mg/ yr ( 25 tpy) or more of any combination of HAP. Area sources are those stationary sources or groups of stationary sources that are not major sources. Our calculations indicate that there are some small softwood plywood and particleboard facilities that are area sources.

<IP_ADDRESS> Comment: Two commenters ( IV D 23 and IV D 35) objected to the inclusion of consent decree plants in MACT floor determinations. Commenter IV D 23 stated that only control devices installed for PSD, not those at companies under consent decree, should be included in the determination of the MACT floor. The commenter argued that control technologies that were installed at many of those facilities are not the ones that the companies would have chosen if they had not been forced to use that specific technology by law. Both commenters contended that the devices that are in use at these plants and proposed by this rule have many technical and operational problems, including massive energy requirements, generation of non HAP emissions, maintenance issues, and little control of particulates.

Response: We disagree that controls installed as a result of the consent decrees should not have been included in the MACT analysis. The reason controls are installed has no bearing on whether they are included in the MACT analysis, which is required to be based on emissions levels achieved for any reason. However, we note that the results of our MACT floor calculations would have been the same regardless of whether or not the consent decree controls were included in the calculations.

<IP_ADDRESS> Comment: Commenter IV D 45 stated that if the EPA could not gather enough data to determine the best 12 percent for any one type of process unit, then it should not use insufficient data as a basis for developing a MACT floor for groups that contain process units that are completely different from one another. The commenter stated that, because the data set is 2 82 incomplete and different process units have such a wide range of operating conditions, EPA should not automatically assume that no control or incineration based controls and biofilters are the best choices for MACT floors for every type of unit. The commenter further stated that EPA should consider several factors when trying to determine the " best" control technologies,

including population density ( the number of people affected by the HAP) and other pollutants emitted by the device. According to the commenter, choosing the control device for the MACT floor based on the emissions alone also tends to select the most expensive controls.

Response: See the response to comment <IP_ADDRESS> regarding insufficient information for MACT floor determinations. Section 112( d)( 3) of the CAA dictates the minimum control level allowed for NESHAP, commonly referred to as the " MACT floor." Section 112( d)( 3) states that " The maximum degree of reduction in emissions that is deemed achievable for new sources in a category or subcategory shall not be less stringent than the emission control that is achieved in practice by the best controlled similar source, as determined by the Administrator. Emission standards promulgated under this subsection for existing sources in a category or subcategory may be less stringent than standards for new sources in the same category or subcategory but shall not be less stringent, and may be more stringent than  ( A) the average emission limitation achieved by the best performing 12 percent of the existing sources ( for which the Administrator has emissions information) ...... in the category or subcategory for categories and subcategories with 30 or more sources..."

The CAA requires NESHAP to reflect the maximum degree of reduction in emissions of HAP that is achievable. This level of control is commonly referred to as MACT. Section 112( d)( 2) of the CAA dictates how we must establish MACT. The MACT can either be established at the MACT floor, or can be some control level more stringent than the MACT floor (" beyond the floor"). Section 112( d)( 2) states that " Emissions standards promulgated under this subsection and applicable to new or existing sources of hazardous air pollutants shall require the maximum degree of reduction in emissions of the hazardous air pollutants subject to this section ( including a prohibition on such emissions, where achievable) that the Administrator, taking into consideration the cost of achieving such emission reduction, and any non air quality health and environmental impacts and energy requirements, determines is achievable for new or existing sources in the category or subcategory to which such emission standard applies..." 2 83 Section 112( d)( 3) of the CAA does not allow us to consider cost when determining MACT floors. This is evident because cost is not mentioned in § 112( d)( 3) regarding minimum stringency levels. Cost is mentioned in § 112( d)( 2) for purposes of assessing the feasibility of more stringent standards. Thus, we are only allowed to consider costs and other non air quality environmental or energy impacts when we examine beyond the floor control options according to § 112( d)( 2) of the CAA. Population density and health risk are not considered in either the MACT floor or MACT analysis, and these analyses are based on technology.

<IP_ADDRESS> Comment: Commenters IV D 19, IV D 21, IV D 27, IV D 34, IV D 35, IV D

37, and IV D 56 argued that Method 204 compliance should not be a part of the PCWP MACT floor because most of the press enclosures that were described as having full, PTEs were never certified by Method 204 criteria. Commenter IV D 27 argued that Method 204 cannot be applied practically to the hot presses that are used at PCWP facilities. The commenter stated that Method 204 was developed for situations where the gas emissions have consistent properties, but a press with multiple openings emits a variety of gases with different physical properties, and heat changes those properties even further. According to the commenter, instead of mixing and exiting the enclosure, the layers of gases can accumulate with other hazardous substances and create a dangerous environment for employees. The higher layers of gas have a greater pressure than the air outside the press and the lower layers have a pressure less than that of the air outside the press. The commenter maintained that to force the gases outside the enclosure, the operator must decrease the temperature of the gas or increase the airflow through the system. To force the gases out of the enclosure, the airflow would have to be about 3 to 4 times higher than would be necessary for an enclosure operating at a homogenous temperature.

The commenter noted that the majority of the industry's press enclosures used to define the floor were retrofit installations around existing conventional multiple opening and short continuous presses. Most of these enclosures were designed according to Method 204 design criteria, but their permits never required them to comply fully with Method 204 certification. Of 26 PTEs surveyed by NCASI, only two actually met Method 204 certification. Commenter IVD 27 noted that EPA identified a total of 207 non plywood and 431 total panel presses, and the minimum number of presses needed to establish a floor is about 12 for 6 percent of 207 nonplywood presses, or about 26 presses for 6 percent of 431 total panel presses. However, only 2 2 84 presses of the 68 percent that responded to the NCASI survey have certified enclosures,

indicating that Method 204 certification should not define the MACT floor. Commenters IV D

34 and IV D 35 argued that the proposed " containment efficiencies" ( capture efficiencies) should be reduced or eliminated in favor of a " best practices" approach and that a total enclosure should only be considered for the installation of a new press. Commenter IV D 37 argued that neither a Method 204 certified PTE nor a 95 percent capture efficiency should be used to determine the MACT floor.

Several commenters ( IV D 19, IV D 21, and IV D 27) suggested that EPA address the press capture efficiency issue by implementing work practice requirements. To reflect this change, commenters IV D 19 and IV D 27 requested that EPA modify the definition of permanent total enclosure in section 63.2292 ( What definitions apply to this subpart?) as follows:

Permanent Total Enclosure ( PTE) means a permanently installed containment that was designed to meet the following physical design criteria: 1. Any NDO shall be at least four equivalent opening diameters from each THC emitting point unless otherwise specified by the Administrator. The MACT floor configuration of the PTE includes capturing emissions from the press unloader. For purposes of determining compliance with criteria 1, the distance from the THC emitting point will be considered to the press. 2. The total area of all NDOs shall not exceed 5 percent of the surface area of the enclosure's four walls, floor, and ceiling. 3. The average facial velocity ( FV) of air through all NDOs shall be at least 3,600 m/ hr ( 200 ft/ min). The direction of airflow through all NDOs shall be into the enclosure. 4. All access doors and windows whose areas are not included in section 2 and are not included in the calculation of FV in 3 shall be closed during routine operation of the process. 5. Fugitive emissions shall be minimized through appropriate operation and maintenance procedures applied to the PTE system.

Commenter IV D 21 suggested a similar definition of PTE, but with different wording in item 1 as follows:

1. Any natural draft opening ( NDO) shall be at least four equivalent opening diameters from each VOC emitting point, except where mat enter the enclosure and the board from the unloader exists the enclosure, or unless otherwise specified by the Administrator.

Commenters IV D 19 and IV D 27 further suggested that the following definition be added for those enclosures that do not meet the design criteria for a PTE ( e. g., partial enclosures): 2 85 Non Permanent Total Enclosure ( Non PTE) means an enclosure that does not meet the Permanent Total Enclosure criteria ( see PTE).

Commenters IV D 19, IV D 21, and IV D 27 suggested that any press enclosure that is not considered a PTE should be required to demonstrate a combined 90 percent capture and control efficiency using the tracer gas method, EPA Method 204A through 204F, or some other method subject to the approval of the Administrator, along with the appropriate test method for the compliance pollutant. If the enclosure does not achieve 90 percent capture efficiency, the commenters suggested that it could be balanced either by emissions averaging or by achieving a higher destruction efficiency.

Response: Although EPA Method 204 was developed for enclosures in the printing and publishing industry, EPA Method 204 is a used to evaluate enclosures in many industries other than the printing and publishing industry. At the time of proposal, we believed that many of the PCWP press enclosures for reconstituted wood products presses were meeting EPA Method 204.

However, based on review of available permit information, we agree with the commenters'

assessment that few permits have required full Method 204 certification for reconstituted wood products press enclosures, although many of these press enclosures were constructed based on the Method 204 design criteria. Prior to proposal, industry explained the technical difficulties associated with evacuating PCWP press enclosures, but we did not distinguish between press enclosures designed to meet EPA Method 204 versus those press enclosures that are actually certified as meeting Method 204. We now understand that the nature of the batch pressing operations in the PCWP industry makes Method 204 certification difficult. Unlike in the printing and publishing industry, operation of batch PCWP presses is cyclical and is a heated operation. A resinated wood mat enters the PCWP press, the press closes and presses the mat under heat ( approximately 400 ° F) and pressure for about 5 minutes. The press then opens and the hot board exits the press. Some steam and emissions escape from the board while the press is closed, but the majority of the steam and emissions are exhausted from the board as the press opens. Steam and emissions continue to off gas from the board in the press unloader. The temperature and density of gases inside the press enclosure change as the press opens and closes, creating layers of gases with different physical properties. The introduction of fresh air and/ or heat radiated from hot pipes around and underneath the press adds another layer of gas with different characteristics 2 86 into the press enclosure. The variation in physical properties in these layers of gases prevents the gases from mixing, moving, and exiting the press enclosure. Industry experience with these heated enclosures suggests that a neutral pressure zone is formed by the layers of gases, and this zone fluctuates between the middle and upper sections of the hot press. The top of the enclosure has a higher pressure than the air outside of the enclosure; whereas the bottom of the enclosure has a lower pressure than the outside of the enclosure. Based on computational fluid dynamics modeling, the industry estimates that to overcome these internal pressure zones, the exhaust through the control system must be increased significantly ( e. g., 3 to 4 times higher than if the enclosure operated at a homogeneous temperature). Because of the internal pressurization within PCWP press enclosures, small amounts of fugitive emissions may appear around the outside of these enclosures. Even so, the PCWP press enclosure is capturing essentially 100 percent of the press emissions. The concern is that because of these small amounts of fugitive emissions,

facilities cannot certify that their Method 204 designed press enclosure can achieve all the Method 204 criteria, in particular the criteria in Method 204 section 6.2 which states that " All VOC emissions must be captured and contained for discharge through a control device." While we believe that PCWP press enclosures should be designed to capture emissions under normal conditions, we do not believe it is necessary for PCWP facilities to increase the flow rate from their press enclosures ( and the size of their APCD) 3 to 4 times to overcome the pressurization within the press enclosure. For the PCWP industry, we believe it would be particularly inappropriate to require such a large increase in exhaust flow to the APCD because the exhaust flow from PCWP process equipment, including presses, is a high volume dilute concentration stream. High volume, low concentration exhaust streams generally are more costly to treat than low volume, concentrated emission streams. The best performing press enclosures that defined the MACT floor surround heated presses and are all believed to have pressurization within the press enclosure. In addition, we note that board cooler exhaust is sometimes directed into press enclosures and that enclosures around board coolers have not been certified according to EPA Method 204. Therefore, instead of requiring EPA Method 204 certification of PCWP press and board cooler enclosures as proposed, today's final rule sets forth slightly different criteria for press and board cooler enclosures. These criteria are based on the design criteria for PTEs 2 87 included in EPA Method 204. Today's final rule contains the following definitions of " wood products enclosure" and " partial wood products enclosure":

Wood products enclosure means a permanently installed containment that was designed to meet the following physical design criteria: 1. Any natural draft opening ( NDO) shall be at least four equivalent opening diameters from each HAP emitting point, except for where board enters and exits the enclosure, unless otherwise specified by the Administrator. 2. The total area of all NDOs shall not exceed 5 percent of the surface area of the enclosure's four walls, floor, and ceiling. 3. The average facial velocity ( FV) of air through all NDOs shall be at least 3,600 m/ hr ( 200 ft/ min). The direction of airflow through all NDOs shall be into the enclosure. 4. All access doors and windows whose areas are not included in 2 and are not included in the calculation of FV in 3 shall be closed during routine operation of the process. 5. The enclosure is designed and maintained to capture all emissions for discharge through a control device.

Partial wood products enclosure means an enclosure that does not meet the design criteria for a wood products enclosure, as defined in this subpart.

The " wood products enclosures" meeting the criteria in the definition above are assumed to achieve 100 percent capture of emissions. Because the capture efficiency of " partial wood products enclosures" is unknown, today's final rule requires facilities to test the capture efficiency of partial wood products enclosures using EPA Methods 204 and 204A F ( as appropriate), or using the alternative tracer gas procedure included in Appendix A to subpart DDDD. In addition,

facilities have the option of using other methods for determining capture efficiency subject to the approval of the Administrator. As was proposed and suggested by the commenters, today's final rule requires facilities using partial wood products enclosures to demonstrate a combined 90 percent capture and control efficiency for those facilities showing compliance with the percent reduction requirements for APCDs . If the partial wood products enclosure does not achieve high capture efficiency, then facilities must offset the needed capture efficiency by achieving a higher destruction efficiency or with emissions averaging ( with the press being an under0controlled process unit).

Today's final rule also requires, as proposed, that facilities showing compliance with one of the APCD outlet concentration compliance options must meet 95 percent capture. The 95 2 88 percent capture requirement was chosen because MACT requires a 90 percent reduction in HAP emissions. Some MACT control devices that perform exceptionally well can get 95 percent control provided that the control device is well maintained and operated over time. In order to use a partial wood products enclosure that achieves less than 100 percent capture, facilities must offset the lesser capture efficiency by a greater control efficiency ( i. e., 95 percent). A 95 percent control efficiency must be combined with a 95 percent capture efficiency in order to achieve the 90 percent reduction required to meet MACT.

2.3.3 Beyond the floor analysis <IP_ADDRESS> Comment: Commenter IV D 07 pointed out that EPA makes a good argument for going beyond the MACT floor in the discussion of the emission averaging program in the preamble to the PCWP rule. The commenter pointed to language in the preamble stating that process units such as blenders may emit the same amount or even more HAP than the dryers and presses that the rule will control, and they usually have a lower volume of gas to treat. However,

when deciding whether or not to go beyond the MACT floor, EPA says that the environmental benefit of controlling these units would not justify the cost. The commenter noted that 74 percent of the affected facilities will have to install new control devices, and because these other process units have a low exhaust flow rate, it would not be difficult to design the control devices to handle the additional small volume.

Response: We are not allowed to consider costs when determining the MACT floor, and therefore, some process units with high flow rates and low concentrations of pollutants are required to be controlled at the MACT floor control level. However, the CAA gives us the authority to consider costs and environmental benefits when looking beyond the MACT floor.

We considered going beyond the floor for all process units. We determined that there were no beyond the floor control options for process units groups with MACT floors based on incineration based controls or biofilters because no technology is currently available that achieves a greater reduction in emissions. For other process units, we considered beyond the floor measures including pollution prevention and incineration based controls. The commenter is correct in that some blenders exhibit comparable HAP emissions, but lower exhaust flow, than the dryers and presses with a MACT floor of incineration based control or biofilter control. In fact,

blenders have the some of the highest emissions of the process units with potential beyond the 2 89 floor options ( e. g., 28 tpy). Most other process units for which beyond the floor control options were considered had significantly lower emissions ( e. g., many had emissions less than 1 tpy).

At the time of proposal, we estimated that 166 of the 233 major source facilities ( i. e.,

74 percent) would need to install new APCDs to meet the MACT standards. Many facilities installed APCDs after we completed our proposal analyses ( which were based on April 2000 equipment and APCD counts). Thus, many facilities have APCDs in place and those APCDs are unlikely to have the capacity to accept additional flow from process units such as blenders. Also,

some facilities may have physical difficulty routing emissions from green end operations ( e. g.,

blenders, digesters) to APCDs located after drying or pressing operations, because the dryers and presses may be located a long distance away from the green end emission points. In addition, our analyses indicated that several plants would need to use most of an RTO's capacity to control emissions from process units with a MACT floor of incineration based control. For these reasons, we determined that it would be inappropriate for our beyond to floor analysis to assume that all facilities can treat emissions in RTOs installed to meet the MACT floor requirements for most dryers and presses. In our beyond the floor analysis, we determined that the environmental benefit of controlling blenders and other process units would not justify the cost, especially given the already high costs of the PCWP rule at the MACT floor control level. We maintain that we did the beyond the floor analysis correctly, and that going beyond the floor for these other process units is not warranted. Our MACT beyond the floor analysis for each process unit is documented in a separate memorandum. 13 2.4 NEW SOURCE MACT Comment: Commenter IV D 11 noted that EPA chose to assign the same degree of control for new and existing sources for many process units based on the fact that the best technology is the same for new and existing sources ( i. e., thermal incineration or biofilters).

Based on the BID, the commenter pointed out that the maximum percent control efficiency is in the upper 90' s for THC, formaldehyde, or methanol. The commenter noted that the CAA requires the MACT floor to be based on the degree of emissions reduction achieved in practice by the best controlled similar source. Thus, the commenter requested that EPA add new source MACT 2 90 requirements for process units based upon the greatest reductions recorded and included in the final rule.

Response: To determine the MACT floor control level for new sources, we used an approach similar to the approach used for existing sources ( see response to comment <IP_ADDRESS> for details). First, based on available data, we determined that incineration based controls ( including RTOs, RCOs, and incineration of pollutants in onsite process combustion equipment used to control emissions from various PCWP process units) and biofilters ( used to control PCWP press emissions) are the only two types of add on APCDs that consistently and continuously reduced HAP emissions. The performance data for the incineration based controls and biofilters showed methanol and formaldehyde emissions reductions equal to or greater than 90 percent, except in those cases where the pollutant loadings of the emission stream entering the control systems were very low. The performance data for THC showed that incineration based control systems achieved THC emissions reductions equal to or greater than 90 percent. The average THC emissions reductions achieved with biofilters was about 80 percent. However, biofilters achieved HAP emissions reductions equal to or greater than 90 percent. Both incineration based controls and biofilters achieved identical formaldehyde and methanol emissions reductions.

We ranked the process units within each process unit group according to the HAP control devices that were applied. We based the MACT floor for new sources on the highest ranked process unit ( i. e., the best controlled similar source). When we ranked the process units, we treated process units equipped with any type of incineration based control system or biofilters as being equivalent with respect to their potential to reduce HAP emissions. We ranked the process units by control device rather than actual unit specific emissions reductions because we have limited inlet/ outlet data on which to calculate control efficiency ( i. e., inlet/ outlet data are not available for many of the controlled process units). As discussed in responses to comment <IP_ADDRESS>, we believe that ranking process units based on actual emissions reduction ( as opposed to ranking by APCD type) is not feasible and is unnecessary for the PCWP source category.

We acknowledge that some incineration based controls and biofilters can achieve greater than 90 percent reduction in formaldehyde, methanol, or THC during a single performance test or a test run within a performance test. However, we also recognize that the percent reduction achieved varies according to pollutant inlet concentration, a factor that is not directly controllable 2 91 from a process or control device standpoint. Other unknown factors may also cause variability in control system performance. In addition, there is variability related to emission measurements.

For example, we have THC percent reduction data for an RTO used to control emissions from three tube dryers and a press at an MDF plant for two emission tests conducted at different times.

In 1996, the RTO achieved 92.7 percent reduction of THC, and in 1998 the same RTO achieved 98.9 percent reduction of THC. In addition, we have emissions test data for the same process unit and control system for multiple years, and these data show different emission factors,

indicating that variability is inherent within each process unit and control system combination.

Thus, we estimate that the best MACT technology achieves 90 percent HAP reductions when variations in operations and measurements are considered.

As stated previously, no technology is currently available that achieves a greater reduction in emissions than incineration based controls or biofilters. Therefore, no beyond the floor control options were considered for process unit groups at new sources with MACT floors based on incineration based control or biofiltration. We considered beyond the floor measures including pollution prevention and incineration based controls for other process units at new sources. Our data do not show that any emission reduction is achieved through use of potential pollution prevention measures ( e. g., using direct versus indirect fired dryers, using a certain fuel to direct fire dryers, etc.) that may be technically feasible for application at new sources. Therefore, our beyond the floor analysis focused on add on controls. Like in our beyond the floor analysis for existing sources, we concluded that the costs of beyond the floor control measures for process units at new sources are not justified by the environmental benefits. 13 2.5 AIR POLLUTION CONTROL DEVICES 2.5.1 General <IP_ADDRESS> Comment: Commenter IV D 08 pointed out that if EPA wishes " to encourage private industry investment in emissions reduction, you must consider providing safe assurances that controls installed will remain acceptable." The commenter noted that a WESP, considered to represent " best available control technology ( BACT)" in 1997, was voluntarily installed on a veneer dryer at one facility at a cost of $ 1.5 million. For the PCWP NESHAP, EPA is requiring that RTOs be installed on dryers instead. The commenter contended that companies now will 2 92 think twice about installing voluntary controls for fear of installing the " wrong" control technology.

Response: Major stationary sources subject to PSD must conduct an analysis to ensure the application of BACT. During each BACT analysis, which is done on a case by case basis, the reviewing authority evaluates the energy, environmental, economic and other costs associated with each alternative technology, and the benefit of reduced emissions ( e. g., criteria pollutants,

VOC) that the technology would bring. The final PCWP rule is based on MACT for HAP emissions; therefore, decisions on control levels and compliance demonstrations are based on HAP reductions. The MACT for veneer dryers was determined to be the emission reduction achievable with incineration based control. We note that MACT for veneer dryers was established at the MACT floor control level, which does not consider costs. While many of the PCWP provisions for HAP may be used to comply with PSD, the PCWP provisions are not universally applicable. In cases where one rule is more stringent than the other, you must comply with both rules.

We acknowledge that many veneer dryers have been equipped with WESPs or wet scrubbers to reduce blue haze. These wet control devices are effective at reducing blue haze and PM emissions, but are not reliable technologies for reducing gaseous HAP emissions. While WESP and wet scrubbers may absorb some water soluble HAP, these same HAP will eventually be re emitted as the recirculating WESP or scrubber water and becomes saturated with these pollutants. We note that facilities may use any control technology to meet the MACT standards provided that the technology meets the compliance options. Facilities choosing to use a WESP to meet the MACT standards may petition the Administrator for approval of site specific operating requirements that can be used to demonstrate continuous compliance. Alternatively, facilities using WESP may use a THC continuous emissions monitoring system ( CEMS) to show that the THC concentration in the WESP exhaust remains below the minimum concentration established during the performance test. Facilities using wet control devices also must submit with their Notification of Compliance Status, a plan for review and approval to address how organic HAP captured in the wastewater from the wet control device is contained or destroyed to minimize rerelease to the atmosphere such that the desired emission reduction is achieved. 2 93 2.5.2 Definition of control device <IP_ADDRESS> Comment: Two commenters ( IV D 03 and IV D 27) requested that scrubbers be added to the definition of " control device." Commenter IV D 27 also requested that adsorbers and scrubbers be added to the definition and that condensers be omitted. Based on the commenters' recommendations, the definition of control device would be modified as follows ( suggested additions are in italics and suggested deletions are in strikeout format):

Control device means any equipment that reduces the quantity of a hazardous air pollutant that is emitted to the air. The device may destroy the hazardous air pollutant or secure the hazardous air pollutant for subsequent recovery. Control devices include, but are not limited to, thermal or catalytic oxidizers, combustion units that incinerate process exhausts, biofilters, absorbers, adsorbers, and scrubbers and condensers.

Response: We disagree with the commenters that the proposed definition of " control device" should be changed. In the proposed PCWP rule we intentionally left absorbers ( e. g., wet scrubbers) out of the list of potential control devices because these technologies generally are not reliable for reducing HAP emissions. These wet systems may achieve short term reductions in THC or gaseous HAP emissions; however, the HAP and THC control efficiency data, which range from slightly positive to negative values, indicate that the ability of these wet systems to absorb water soluble compounds ( such as formaldehyde) diminishes as the recirculating scrubbing liquid becomes saturated with these compounds. 2 We wished to limit the examples included in the definition of " control device" to those devices for which we have data to demonstrate that they are effective in reducing HAP emissions from PCWP facilities. However, we note that the definition includes the phrase " but not limited to," so the definition does not exclude other types of controls. We are aware that new technologies ( some of which may be adsorption based or absorption based) may be developed that effectively reduce HAP emissions from PCWP sources.

The definition of " control device" does not prevent their development or use.

Facilities using wet scrubbers or WESPs to meet the add on APCD or emissions averaging compliance options can petition the Administrator for approval of site specific operating requirements to be used in demonstrating continuous compliance. Alternatively,

facilities using a wet scrubber or WESP may use a THC CEMS to show that the THC concentration in the APCD exhaust remains below the minimum concentration established during the performance test. In addition, facilities using wet control devices ( e. g., wet scrubber or 2 94 WESP) as the sole means of reducing HAP emissions must submit with their Notification of Compliance Status a plan for review and approval to address how organic HAP captured in the wastewater from the wet control device is contained or destroyed to minimize re release to the atmosphere such that the desired emission reduction is achieved. Because wet scrubbers and WESPs are add on APCDs and have variable effects on HAP emissions, the final rule specifies that sources cannot use add on control systems or wet control devices to meet the PBCO.