### Further Explanation ofDecision, February 2015 This Memorandum provides EPA Region I's detailed analysis regarding the determinationbeing made that Vermont'sprogram regulating wastewater evaporation units is
more protective ofhuman health and the environmentand therefore not less stringent than the federal approach. This supplements the analysis set forth in the Federal Registernotice. Wastewater evaporation units (evaporators) (as further defined by Vermont) evaporate water using heatto reduce the volume ofwastewater and to concentrate hazardous wastes. Vermontregulates these units using the conditions ofits permit exemption for generator treatment in tanks and additional conditions designed to effectively regulate evaporators. EPA has analyzed whetherthe Vermontregulations are equally ormoreprotective ofhuman health and the environment than the federal regulations, rather than beingless stringent. EPAhas determined that they are more protective /stricter, thus being withinthe State's authority to maintain. See RCRA section 3009 (precluding only less stringent state requirements). Todetermine that the stateregulations are stricter and not less stringent than the federal regulations, EPAhas compared the state regulations to the federal regulations, including examining interpretations that have been made ofthe federal regulations (available in the administrative record and in RCRA Online). However, in line with the national policy: Determining Equi valency ofState RCRA Hazardous Waste Programs, September 7, 2005 (Equivalency Policy), EPAhas notrequired that the state follow the same identical approach as the federal regulations. Rather, EPAhas focused, "on whether the state requirements provide [at least] equal environmental results as the federal counterparts." ld. At the federal level, the wastewatertreatment unit (WWTU) exemption has been interpreted to cover many hazardous waste evaporators. Inthe Cervino letter (Jan. 16, 1992), 

### 1EPA advised that any facility that has ever had a water discharge is considered to be subject to the exemption. EPA has further advised that all dry cleaning establishments may claim the exemption. Fisher letter , June 2, 1993. EPA also has advised that facilities with zero water

discharge systems may obtain water permits whether or not required to do so by the water

program , and then will qualify for the exemption. Elliott letter , Mar. 20 , 1989. While this interpretation was first stated with respect to facilities switching from water di sc harges to zero discharge systems, it has been applied to allow facilities that ne ver have discharged to the water to obtain water permits and thereby qualify for the exemption. Vermont is stricter than this federal approach in that it excludes wastewater evaporation units f rom being covered under its WWTU exemption. VHWMR § 7-103. Rather, it regulates them under its more protective generator treatment in tanks exemption. VHWMR § 7-502(o)(8). At the federal level, the only general RCRA requirement under the WWT U exemption is that the evaporator treatment occur in a tank or tank system (see 40 C.F.R. § 260.10 definition). Additionally, Vermdnt requires meeting the fuil range of generator requirements for large quantity generators (LQGs) and small quantity generators (SQGs ), such as req u iring secondary containment around the tanks, contingency planning, and for large quantity generators, meeting the RCRA air emission control standards in 40 C.F.R. part 265, subparts AA , BB and CC. See VHWMR § 7-502(o) and cross-referenced provisions. Vermont is also stricter by more extensively regulating conditionally exemp t small quantity generators (CESQGs). At the federal level, persons treating certain 0001 (ignitable) and 0003 (reactive) wastes in evaporators under the WWTU exemption also must follow specified safe handling requirements (see 40 C.P.R. § 264.l(g)(6)). Vermont is stricter by requiring evaporators treating all hazardou s wastes to follow s uch safe handling r eq uirements. See VHWMR § 7 - 502(o)(8)(B). 2The Vermont regulations forthe generator treatment 

### intanks exemption are stricter than that federal exemption. Vermont imposes a general conditionthat treatment inevaporation units "shall result inthe concentration ofhazardous waste constituents for properrecycling or disposal, and not allow evaporation ofthe hazardous waste constituents into the air." VHWMR 

### § 7-502(o)(8)(A). Vermont requires as a condition for obtaining any RCRA permitting exemption that the generator beincompliance with all applicable federal and state air emission control requirements. !d. Vermont explicitly prohibits any "disposal" ofhazardous waste through evaporation. VHWMR § 7-302(a). Finally, Vermont requires that any generator seeking to operate an evaporator must provide noticeto the Vermont Department of Environmental Conservation (Department). VHWMR 

### § 7-502(o)(l). As represented in the sta te'sapplication for authorization, the Department then reviews and approves all notifications. When appropriate, the Department may impose additional case by case standards as a condition ofapproval. Vermont has reserved the right to add case by caserequirements in VHWMR 

### § 7- 312. Thus, the Vermont regulations are stricter than the federal regulations with respect to the many evaporators which qualifY for the federal WWTU exemption. However, there may be
some evaporators that do not qualify for the WWTU exemption atthe federal level. This generally could include facilities thathave never discharged to the water, are not dry cleaners, andhave not obtained zero discharge waterpermits. Underthe federal approach, some ofthe facilities that do not currently have zero discharge waterpermits might obtain them and thereby also qualify in the future for the exemption. However, there maybe some facilities that could
never qualifY for the exemption. Aspart ofthe process ofcomparing the state regulations to the federal regulations, EPA has examined what the approach would be for such facilities at the
3federal level , in particular whether such facilities could qualify for the federal generator treatment in tanks exemption. Since 1986, the EPA has generally allowed generators to conduct treatment in tanks (and containers) without permits, if they comply with all applicable generator tank (and container) management standards. 51 Fe d. Reg. 10146 (Mar. 24, 1986). Since 1987, however, th e EPA has advised tha t there is an exception to this general allowance in that "thermal treatment" by generators without permits is not allowed. Memorandum by OSW Director, Dec . 15, 1987 . The

resulting question is whether at the federal level evaporation is considered to be " thermal treatment" for purposes of the generator treatment in tanks exemption, thus requiring a thermal

treatment permit, or is allowed to be conducted without permits in tanks by generators . Under the WWTU unit exemption, the E PA has determined that evapora to rs do not require thermal treatment permits. While thermal treatment units such as incinerators do not qualify for the WWTU exemption (see Olsen letter, Aug. 3, 1987) , the Agency determined that evaporators should continue to qualify as 'treatment in tanks' under the WWT U exemption rather than being required to meet thermal treatment permitting standards. 56 Fed. Reg. 7134 ,

7202 (Feb. 21, 1991 ). Under the WWTU exemption, the Agency has distinguished between higher risk units which use thermal treatment to destroy or treat the hazardous constituents in waste and units whlch only evaporate water so as to concentrate wastes. 55 Fed. Reg . 29230, 29232 (July 18, 1990). The latter kind of units have not been required to obtain thermal treatment permits. Thus the approach followed by the EPA under the WWTU exemption has been to not classify evaporation units as "thermal treatment" units requiring thermal treatment permits. The EPA initially issued guidance that evaporators similarly could qualify for the 4

### generatortreatment intanks exemption (i.e., did not need permits). Sasson letter, May I, 1987 and Cervino letter, Jan. 16, 1992. However, in 1994, theEPA determined that thermal fuel blendingtreatment was not allowedunder the generator treatment intanks exemption. Memorandum from OSW Director, 

### Oct: 17, 1994. Although the Oct. 11 Memorandum did not discuss evaporators, a note was then attached to the Sasson letterindicatingthat it had been superseded bythe Oct. 17, 1994 memorandum. Although no such note was attached to the Cervino letter, we have assumed for purposes ofthe Region's authorization decision that the current EPA interpretation ofthe federal regulations is setby the note attached to the Sasson letter. The Region has thus assumed that at the federal level, evaporation treatment by generators withoutpermits is not allowed under the generator treatment in tanks exemption, but rather is only allowed at facilities which qualify for the WWTU exemption. We believe that any regional decision should take account ofthe most stringentcurrent national approach, unless and until that approach is changed atthe national level. However, for the reasons explained below, the Region has nevertheless determined that the Vermont regulations are stricter, not less str ingent than, the federal regulations. EPAhas concluded that we should look atthe overall RCRAprogram and assess the effect oftheVermont program across the board. In doingthat, EPAhas concluded that the Vermont program is stricter than any ofthefederal requirements with respect to wastewater evaporators. RCRA §

### 3009. Vermont consistently and strictly regulates all generator . evaporators by imposing hazardous waste management requirements and comprehensive air emissions regulations. This is stricter across the board than the federal approach, and thus should be allowed consistent with the national Equivalency Policy, which emphasizes that states may take different but equally or more protective approaches. 

### 5It also should be noted that the Vermont regulations require the same type of tank management standards and air emission control requirements as would be included in permits. Additional l y, Vermont requires every generator operat i ng an evaporator to submit a notice and obtain review of its operation , similar to what would occur if the generator was required to apply for a permit. Thus even if one looks at just those evaporators not subject to the federal WW TU exemption, Vermont arguably has equivalent permit-like controls in place. However, the Region need not decide this issue but rather may assess the stringency of the Vermont program across

the board. When one takes account of the fact that the Vermont program is stricter than the federal requirements with res pect to the many evaporators subject to the federal WWTU exemption, it is clear that the Vermont program is stricter across the board. The Region is not departing from national guidance in allowing this different State

approach. Rather, the Region is following the national guidance set forth in the Equivalency policy, which says that States need not necessarily follow every federal approach. As explained in that policy , a State's obligation is to be equally or more protective than the federal program. In the circumstances presented here, where Vermont is being more protective than the federal approach, Vermont is not obligated to also follow the identical federal approach. The Region's decision does not violate the requirement in 40 C.F.R. § 271.13 t hat States must require permits for all hazardous waste management facilities required to obtain permits under 40 C .F.R. part 270. As noted above, the general approach that the EPA has taken to evaporators has been to allow them to operate without permits under the WWT U exemption. In

Vermont's circumstances, section 271.13 should not be interpreted to rule out a state approach that is more protective overall than the federal approach. Also, the Region's decision is not contrary to the broad definition of " thermal treatment" in 40 C.F .R. § 260.10. E PA is not 6opining that evaporators do not fall within such a broad definition. Rather, EPA is opining only that a State program that is more protective across the board is not less stringentthan the federal program. As noted above, the federal program generally does notrequire evaporators to meet thermal treatment requirements (ormost other RCRArequirements). Vermont may classify generator evaporators as not being thermal treatmenttha t requires thermal treatment permits whenthis is partofan overall more protective state approach. There is no express federal statutory orregulatory requirement that generator evaporators must have permits. Rather, the RCRA statutory requirement ist!hat permits must be issued to treatment, storage and disposal facilities (TSDFs). RCRA 

### § 3005. Vermont may take the different approach ofstrictly regulating all generator evaporators without being required to classify those not sub jectto the federal WWTUexemption as TSDFs. EPAemphasizes that the.Region's authorization decision will allow non-permitted evaporation treatment (outside ofthe WWTU exempt ion) only inVermont. Such treatment will be allowed onlybecause ithas been federally authorized as "functionally" equivalent (part ofan across the boardmore protective approach), and this federal authorization isbeing granted based
onthe particular strictrequirements adopted byVermont. EPA further emphasizes that this regional rulemakinghas no implications for howothe r kinds of.. thermal treatment" will be regulated. Generally "thermal treatment" is not allowed without permits under eitherthe generatortreatment 

### intanks (and containers) exemption orunderthe WWTU exemption. Inthe Region's authorization decision, the Region is only allowing, subject to stricter Vermont standards, the same type ofevaporation treatment thatalready hasbeen allowed without permits under the WWTUexemption at thefederal level and in the many states that follow thefederal approach. 7Finally, EPA notes that Vermont is stricter than the federal approach with respect to any evaporators located at Treatment, Storage and Disposal Facilities (TSDFs). These evaporators must always obtain RCRA permits in Vermont, since Vermont does not allow the use of the WW TU exemption for evaporators, and Vermont's treatment in tanks permit exemption for evaporators is limited to generators. Jeffry Fowley, Office of Regional Counsel, EPA Region I 8