Meritor, Inc. v. EPA ( 2020 )


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  •  United States Court of Appeals
    FOR THE DISTRICT OF COLUMBIA CIRCUIT
    Argued November 7, 2019                 Decided July 28, 2020
    No. 18-1325
    MERITOR, INC.,
    PETITIONER
    v.
    ENVIRONMENTAL PROTECTION AGENCY,
    RESPONDENT
    On Petition for Review of Agency Action of the
    United States Environmental Protection Agency
    Catherine E. Stetson argued the cause for petitioner. With
    her on the briefs were Mitchell P. Reich, Heidi B. Friedman,
    and Joel Eagle.
    James R. Bieke, C. Frederick Beckner III, Peter C.
    Tolsdorf, Steven P. Lehotsky, and Michael B. Schon were on
    the brief for amici curiae the National Association of
    Manufacturers, et al., in support of petitioner. Linda E. Kelly
    entered an appearance.
    John Thomas H. Do, Attorney, U.S. Department of Justice,
    argued the cause for respondent. With him on the brief was
    Jonathan D. Brightbill, Principal Deputy Assistant Attorney
    General. Jon M. Lipshultz, Attorney, entered an appearance.
    2
    Before: MILLETT and KATSAS, Circuit Judges, and
    SENTELLE, Senior Circuit Judge.
    Opinion for the Court filed by Circuit Judge MILLETT.
    MILLETT, Circuit Judge: The Environmental Protection
    Agency maintains a National Priorities List that identifies those
    hazardous waste sites in most urgent need of cleanup based on
    the threat that they pose to public and environmental health and
    to the public welfare. In 2018, the EPA added the Rockwell
    International Wheel & Trim facility and surrounding areas to
    the National Priorities List. Meritor, Inc., which has assumed
    Rockwell International Corporation’s environmental liabilities
    for the facility, challenges the listing as arbitrary, capricious,
    and contrary to governing regulations. Meritor’s main
    objection is that the EPA failed to take sufficient account of an
    already installed sub-slab depressurization system in
    determining the hazardousness of the site. Because the EPA’s
    decision was reasonable and consistent with the governing
    regulatory provisions, we deny the petition for review.
    I
    A
    Congress enacted the Comprehensive Environmental
    Response, Compensation, and Liability Act of 1980
    (CERCLA), 42 U.S.C. §§ 9601 et seq., “to address the growing
    problem of inactive hazardous waste sites throughout the
    United States.” Eagle-Picher Indus., Inc. v. EPA, 
    759 F.2d 922
    , 925 (D.C. Cir. 1985). CERCLA directs the EPA to
    develop “criteria for determining priorities among releases or
    threatened releases” of hazardous waste into the environment.
    42 U.S.C. § 9605(a)(8)(A). Based on those determinations, the
    EPA must maintain a National Priorities List.
    Id. 3
    § 9605(a)(8)(B). That List “identifies those hazardous-waste
    sites considered to be the foremost candidates for
    environmental cleanup” based on “the relative risk or danger
    they pose to the public health, public welfare, or the
    environment.” CTS Corp. v. EPA, 
    759 F.3d 52
    , 55 (D.C. Cir.
    2014).
    The EPA has developed a set of regulations, known as the
    Hazard Ranking System, that it uses to evaluate whether, and
    to what degree, a site poses a risk to the environment or to
    human health and welfare. See generally 40 C.F.R. Part 300,
    App. A.
    Under that scheme, the EPA evaluates up to four
    “pathways” through which hazardous substances can migrate:
    (1) groundwater, (2) surface water, (3) air, and (4) soil
    exposure. 40 C.F.R. Part 300, App. A § 2.1. The soil-exposure
    pathway includes analysis of the extent to which hazardous
    substances intrude from the subsurface.
    Id. In particular, the
    subsurface intrusion component evaluates the emanation (or
    potential emanation) of noxious vapors from the soil into
    occupied buildings.
    Id. § 5.2.0. That
    subsurface intrusion
    factor is the central focus of this case.
    In evaluating each pathway, the EPA weighs three metrics:
    (1) the “likelihood of release” of hazardous waste into the
    environment, (2) the “waste characteristics” of those
    substances (such as the quantity, toxicity, mobility, persistence,
    capacity to degrade, or bioaccumulation potential), and (3) the
    “targets” of the hazardous waste, meaning who will suffer
    exposure, whether humans, animals, natural resources, or
    sensitive environments. 40 C.F.R. Part 300, App. A §§ 2.3–
    2.5.
    Based on those metrics, the EPA assigns a numerical value
    to each pathway, which it then converts into a score between 0
    4
    and 100 for the site as a whole. 40 C.F.R. Part 300, App. A
    § 2.1.1, 2.1.2 & Table 2-1. Sites scoring 28.5 or higher may be
    added to the List. 83 Fed. Reg. 46,408, 46,409 (Sept. 13, 2018).
    Once a site is added to the National Priorities List, it
    becomes eligible for remedial action financed by the EPA’s
    Superfund Program. CTS 
    Corp., 759 F.3d at 56
    ; see also 42
    U.S.C. § 9611. If the EPA chooses to conduct a cleanup, it may
    seek reimbursement from parties who are potentially
    responsible for contributing to the hazard, known as
    “Potentially Responsible Parties.” General Elec. Co. v.
    Jackson, 
    610 F.3d 110
    , 114 (D.C. Cir. 2010) (citing 42 U.S.C.
    §§ 9604(a), 9607(a)(4)(A)).
    B
    From 1966 to 1985, the automotive division of Rockwell
    International Corporation manufactured wheel covers at a
    facility in Grenada, Mississippi, which we shall refer to as the
    Rockwell Facility. The Rockwell Facility borders a residential
    neighborhood, as well as a creek and agricultural land. The
    wheel-cover manufacturing process produced hazardous
    substances, including toluene, trichloroethylene (TCE), and
    cis-1,2-dichloroethene (DCE), which were stored on site. A
    1994 investigation revealed that those operations had led to a
    plume of toluene and TCE collecting in the soil and
    groundwater under and around the Rockwell Facility.
    Exposure to toluene or TCE can cause a range of health
    impairments. Short-term inhalation exposure can result in
    central nervous system dysfunction, leading to headaches,
    dizziness, confusion, and fatigue. Long-term exposure can
    cause even more serious health repercussions. Among other
    things, TCE has been shown to be carcinogenic to humans and
    5
    chronic exposure to high levels of toluene can cause ataxia and
    cerebral atrophy.1
    In 1985, Rockwell International sold the Rockwell Facility
    to another company (that is not a party to this suit). Years later,
    Rockwell International spun off its automotive division into a
    separate corporation called Meritor, Inc. As a result, while
    “Meritor never owned or operated the [Rockwell] Site[,]”
    J.A. 48 n.5, it contractually “assumed various environmental
    obligations in certain areas of the [Rockwell] Site[.]” J.A. 52.
    As Meritor confirmed at oral argument, those environmental
    obligations include assuming Rockwell International’s legal
    liabilities with respect to the Rockwell Facility. Oral Arg. Tr.
    4:25–5:3 (“Meritor * * * took on the liabilities of Rockwell[,]”
    including those associated with “the Rockwell [S]ite.”).
    More recent studies of the Rockwell Facility demonstrate
    the continued presence of hazardous waste, which has in turn
    harmed air quality in the area. J.A. 12–13, 17–18. In October
    2016, the EPA’s study of indoor air quality in the Rockwell
    Facility’s main production building revealed elevated
    concentrations of toluene, TCE, and DCE. In April 2017,
    Meritor commissioned a study that found heightened levels of
    toluene and TCE beneath the surface.
    1
    See United States EPA, Toluene (2016), https://www.epa.gov/
    sites/production/files/2016-09/documents/toluene.pdf; United States
    EPA, Trichloroethylene (2016), https://www.epa.gov/sites/
    production/files/2016-09/documents/trichloroethylene.pdf.; see also
    Agency for Toxic Substances & Disease Registry, 1,2-
    Dichloroethene (1996), https://www.atsdr.cdc.gov/phs/phs.
    asp?id=462&tid=82 (discussing the potential adverse health
    effects of cis-1,2-dichloroethene).
    6
    That same year, Meritor installed a sub-slab
    depressurization system below the Rockwell Facility’s main
    building. The depressurization system was designed to reduce
    the intrusion of contaminated air into the building by creating
    a pressure differential between the building and the underlying
    soil. Despite improvements in air quality following the
    installation of this system, the degree of contamination within
    the main building continued to exceed ambient levels.
    J.A. 585–586.
    On September 13, 2018, after going through notice and
    comment rulemaking, the EPA added the Rockwell Facility
    and surrounding areas (“Rockwell Site”) to the National
    Priorities List based on the hazardous subsurface intrusion of
    toluene, TCE, and DCE. 83 Fed. Reg. at 46,411.
    In evaluating the subsurface intrusion component of the
    soil exposure pathway, the EPA considered the usual three
    factors: the “likelihood of release” of hazardous waste, the
    “waste characteristics” of those substances, and the “targets”
    of such waste. 40 C.F.R. Part 300, App. A §§ 2.3, 2.4, 2.5.
    With respect to the “likelihood of release” factor, the EPA
    either relies on an actual “observed exposure” or measures the
    “potential for exposure.”        40 C.F.R. Part 300, App. A
    §§ 5.2.1.1.1, 5.2.1.1.2. If the EPA documents an observed
    exposure, the “likelihood of release” is automatically assigned
    a maximum value of 550.
    Id. § 5.2.1.1. Here,
    the EPA found
    multiple instances of “observed exposure” based on indoor air
    samples taken in October 2016 and January 2017, before the
    sub-slab depressurization system was operative. So EPA
    assigned the maximum value of 550.
    The EPA assigned a “waste characteristics” score of
    56/100. That score was based on two elements: (1) the level
    of toxicity/degradation of the substances in question, and
    7
    (2) the hazardous waste quantity, which relates to the quantity
    of hazardous material found in regularly occupied structures.
    40 C.F.R. Part 300, App. A §§ 2.4.1, 2.4.2, 5.2.1.2.
    Finally, the EPA analyzed the “targets” factor, which
    accounts for populations and sensitive environments located
    near the contaminated area. The EPA began by selecting an
    “appropriate benchmark” for sorting workers into two tiers.
    Level I applies to individuals who occupy structures where the
    concentration of hazardous substances equals or exceeds the
    health benchmark. 40 C.F.R. Part 300, App. A § 5.2.1.3.1 &
    Table 5-20. Level II applies to individuals who are in
    structures or subunits where there is an observed exposure, but
    where the concentration of hazardous substances falls below
    the benchmark.
    Id. Here, the EPA
    focused on the 217 full-time employees
    working at the Rockwell Facility at the time of the agency’s
    decision. Applying residential exposure assumptions, the EPA
    adopted a benchmark of 0.4 µg/m3 for cancer risk based on
    TCE exposure and 2.0 µg/m3 for non-cancer toxicological
    risk.2 Sorting workers into these two categories yielded a score
    of 707.33 for the “targets” category.
    Based on a complicated formula that we need not navigate,
    the EPA translated those three subcomponent scores into an
    overall hazard score of 50 for the Rockwell Site. That meant
    that based on the subsurface intrusion component alone, the
    Rockwell Site was well above the 28.5 threshold score for
    listing, and the EPA added it to the National Priorities List.
    Given that outcome, the EPA had no occasion to analyze the
    2
    The EPA measures the concentration of toluene, TCE, and
    DCE in micrograms per cubic meter (μg/m3).
    8
    Rockwell Site’s potential listing under the air, surface water, or
    groundwater pathways.
    II
    We have jurisdiction to review the EPA’s listing decisions
    under 42 U.S.C. § 9613(a). Meritorʼs admission that it has
    taken on former site owner Rockwell International’s liability
    with respect to the Rockwell Site, Oral Arg. Tr. 4:25–5:3, is
    sufficient to establish the company’s standing to challenge the
    listing as a possible Potentially Responsible Party. See Mead
    Corp. v. Browner, 
    100 F.3d 152
    , 155 (D.C. Cir. 1996) (finding
    standing where the corporation’s status as a former owner of
    the property in question “would provide a plausible basis for a
    claim that it was a [Potentially Responsible Party]”); see also
    CTS 
    Corp., 759 F.3d at 58
    .
    In reviewing the EPA’s listing decision, we borrow the
    Administrative Procedure Act’s standard of review. Genuine
    Parts Co. v. EPA, 
    890 F.3d 304
    , 311 (D.C. Cir. 2018)
    (reviewing listing decision under the APA standard because
    “CERCLA does not specify a standard of review applicable to
    EPA’s NPL listing decisions”). As a result, the EPA’s decision
    will be set aside only if it was “arbitrary, capricious, an abuse
    of discretion, or otherwise not in accordance with law.” Carus
    Chem. v. EPA, 
    395 F.3d 434
    , 441 (D.C. Cir. 2005) (quoting 5
    U.S.C. § 706(2)(A)).
    In conducting this review, we afford the EPA “significant
    deference” with respect to the “highly technical issues
    involved[.]” Carus 
    Chem., 395 F.3d at 441
    (quoting Bradley
    Mining Co. v. EPA, 
    972 F.2d 1356
    , 1359 (D.C. Cir. 1992)). We
    are also mindful that the National Priorities List is meant to be
    a “rough list of priorities, assembled quickly and
    inexpensively.”
    Id. (quoting Bradley Mining,
    972 F.2d at
    1359); see also Eagle-Picher Indus., Inc. v. EPA, 
    759 F.2d 905
    ,
    9
    911 (D.C. Cir. 1985) (The “major purpose” of the National
    Priorities List and the Hazard Ranking System “is to identify,
    quickly and inexpensively, sites that may warrant further action
    under CERCLA.”).
    III
    In adding the Rockwell Site to the National Priorities List,
    the EPA followed the well-established Hazard Ranking System
    process. The validity of that regulatory framework is not in
    dispute. Oral Arg. Tr. 7:15–8:8, 44:10–17. Meritor also does
    not challenge the Hazard Ranking System’s pathway-based
    approach, nor does it take issue with the inclusion of a
    subsurface intrusion component within the soil exposure
    pathway. Instead, Meritor argues that the EPA improperly
    applied the Hazard Ranking System to the Rockwell Site by
    (1) failing to account for the company’s mitigation efforts,
    (2) relying on improper benchmarks when analyzing the
    “targets” component, and (3) failing to follow the Hazard
    Ranking System’s tiered approach to analyzing the “waste
    characteristics” component. None of these arguments succeed.
    A
    At the outset, Meritor argues that the EPA acted arbitrarily
    and capriciously by evaluating the Rockwell Site based on
    measurements taken before the sub-slab depressurization
    system was installed.
    This court previously “rejected the argument that the EPA
    must consider the effects of remedial measures in scoring a site
    under” the 1982 Hazard Ranking System. Eagle-Picher Indus.,
    Inc. v. EPA, 
    822 F.2d 132
    , 149 (D.C. Cir. 1987); see also
    Linemaster Switch Corp. v. EPA, 
    938 F.2d 1299
    , 1306–1307
    (D.C. Cir. 1991). But, according to Meritor, the “express
    language of the” current Hazard Ranking System strips away
    10
    the EPA’s discretion to disregard remedial measures. Meritor
    Br. 22, 24–26; Reply Br. 8; see also Oral Arg. Tr. 7:15–25.
    Rather, Meritor argues, the operative Hazard Ranking System
    regulations require consideration only of toxic emissions
    occurring after the mitigation system was installed.
    In support of this position, Meritor points to two portions
    of the Hazard Ranking System that expressly account for the
    presence of mitigation measures. Meritor Br. 24 (citing 40
    C.F.R. Part 300, App. A §§ 5.2.1.1.2.1 & Table 5-12,
    5.2.1.3.2.3 & Table 5-21). But the EPA had no need to reach
    or to rely on either of those provisions in this case.
    First, Meritor is correct that, when assessing the potential
    for exposure (in the course of determining the likelihood of a
    release of hazardous waste), the EPA assigns each building a
    structural containment value between 0 and 10 based on a
    number of factors. 40 C.F.R. Part 300, App. A § 5.2.1.1.2.1 &
    Table 5-12. One of those factors is whether a mitigation
    system has been installed.
    Id. But the EPA
    had no occasion to evaluate the potential for
    exposure (and so to consider Meritor’s installation of a sub-slab
    depressurization system) because the agency documented an
    actual, observed exposure at the site. See 40 C.F.R. Part 300,
    App. A § 5.2.1.1.1. Sensibly enough, the regulations do not
    require calculating the “potential” for exposure when the
    reality of actual exposure has already been documented. Res
    ipsa loquitur. Nor do the regulations factor in abatement
    efforts when evaluating whether there has been an observed
    exposure. See
    id. §§ 2.3 Table
    2-3, 5.2.1.1.1. That direct
    observation is why, under the regulations, the EPA
    automatically assigned the maximum score of 550 for the
    “likelihood of release” component without regard to mitigation
    measures. See
    id. § 5.2.1.1.1. 11
         Second, the Hazard Ranking System requires the EPA,
    when it assesses the “population within an area of subsurface
    contamination” component of the “targets” metric, to weight
    the number of occupants based on whether the building has a
    mitigation system installed. 40 C.F.R. Part 300, App. A
    § 5.2.1.3.2.3 & Table 5-21; J.A. 4.
    But in this case, the EPA never relied on the “population
    within an area of subsurface contamination” factor, so it had no
    occasion to look at mitigation measures through that lens. And
    by excluding those points from the computation, the EPA’s
    analysis necessarily resulted in a lower or equal overall score
    for the “targets” metric. See 40 C.F.R. Part 300, App. A § 5.2
    Table 5-11. Meritor can hardly complain about the EPA’s
    failure to look at other factors that would have, at best, left the
    Rockwell Site’s final score right where it was and, at the worst
    for Meritor, resulted in an even higher score.
    Third, Meritor backs off in its reply brief from its initial
    assertion that the listing decision’s failure to consider the
    mitigation measure violated the “the express language of the
    [Hazard Ranking System],” Meritor Br. 22. Instead, Meritor
    argues in reply that the regulations’ sporadic references to
    mitigation systems in some factors implicitly mandate the
    consideration of mitigation systems at every step and for every
    factor in the analysis, Reply Br. 4.
    But that would amend rather than apply the existing
    regulatory scheme. Nothing in the text of the regulations
    imposes such a pervasive requirement to factor in mitigation
    efforts. To the contrary, the Hazard Ranking System’s
    selective inclusion and omission of mitigation systems as a
    consideration suggests “that the omission” of any reference to
    mitigation systems in other “context[s] was deliberate.”
    Council for Urological Interests v. Burwell, 
    790 F.3d 212
    , 221
    12
    (D.C. Cir. 2015) (applying that principle in a statutory
    construction case); see also Yonek v. Shinseki, 
    722 F.3d 1355
    ,
    1359 (Fed. Cir. 2013) (“Where an agency includes particular
    language in one section of a regulation but omits it in another[,]
    [courts] generally presume[] that the agency acts intentionally
    and purposely in the disparate inclusion or exclusion.”)
    (formatting modified); Atlas Tel. Co. v. Oklahoma Corp.
    Comm’n, 
    400 F.3d 1256
    , 1265 (10th Cir. 2005) (similar).
    It certainly was not arbitrary and capricious for the EPA to
    apply its regulations as written.
    B
    Meritor next argues that the EPA acted arbitrarily by
    relying on a residential health benchmark when evaluating the
    “targets” metric.
    The Hazard Ranking System’s categorization of occupied
    structures is multilayered. Bear with us.
    The EPA designates any structure with an observed
    exposure as Level I if the hazardous substance’s concentration
    inside equals or exceeds the “appropriate benchmark[.]” 40
    C.F.R. Part 300, App. A § 5.2.1.3.1. If the concentration of a
    hazardous substance triggers an observed exposure, “but do[es]
    not equal or exceed the appropriate benchmark[,]” the agency
    designates the structure as Level II.
    Id.3
    The relevant benchmarks are the “health-based
    benchmarks from Table 5-20.” 40 C.F.R. Part 300, App. A
    § 5.2.1.3.2. That Table directs the agency to use the
    3
    This same measurement scheme applies to partitioned subunits
    within a structure. 40 C.F.R. Part 300, App. A § 5.2.1.3.1.
    13
    “[s]creening concentration for cancer corresponding to” a one-
    in-a-million risk of cancer.
    Id. § 5.2.1.3.2 Table
    5-20. It also
    instructs the EPA to select a benchmark “for noncancer
    toxicological responses” caused by oral or inhalation exposure.
    Id. Once the EPA
    categorizes each building that has an
    observed exposure as either Level I or Level II, it divides the
    number of occupants in each structure by three if they are full-
    time workers or by six if they are part-time workers. 40 C.F.R.
    Part 300, App. A §§ 5.2.1.3.2.1, 5.2.1.3.2.2. The resulting
    number is then multiplied by 10 for the Level I category.
    Id. § 5.2.1.3.2.1. The
    Level II figure is not multiplied by ten.
    Id. § 5.2.1.3.2.2. These
    modified Level I and Level II values are
    summed, along with the “population within the area(s)” rating,
    to calculate the “population” score for the “targets” metric.
    Id. § 5.2.1.3.2.4.4 When
    selecting the appropriate Hazard Ranking System
    cancer and non-cancer risk benchmarks, the EPA relies on an
    exposure scenario “consistent with a residential
    individual * * * across all * * * pathways[,] as this is most
    protective.” J.A. 648. Such residential health benchmarks are
    based on the assumption that the occupants are exposed to the
    hazardous substance “24 hours per day” and “350 days per
    year” for a duration of 26 years. J.A. 652. Applying this
    approach, the EPA selected TCE benchmarks of 0.4 μg/m3 for
    4
    The “population within the area(s)” subcomponent is typically
    added to the modified Level I and Level II values to obtain the overall
    population score. 40 C.F.R. Part 300, App. A § 5.2.1.3.2.4. The
    EPA did not, however, calculate that subcomponent for the Rockwell
    Site, making that score effectively zero.
    14
    cancer risk and 2.0 μg/m3 for the risk of a toxicological
    response.5
    In Meritor’s view, the Hazard Ranking System’s mandate
    that the EPA select an “appropriate benchmark,” 40 C.F.R.
    Part 300, App. A §§ 5.2.1.3.1, 5.2.1.3.2, requires the agency to
    adopt site-specific exposure assumptions for cancerous and
    toxic health risks. Meritor Br. 38–41. In particular, Meritor
    argues, the EPA should have used an industrial, rather than
    residential, health benchmark because the employees did not
    reside at the Rockwell Facility full time. Rather, they worked
    “8-hour shifts” for “five to seven days per week.” J.A. 41. So
    Meritor advocates for the assumption that workers are exposed
    8 hours per day and 250 days per year for 25 years. Meritor
    Br. 37 (citing J.A. 652).
    Meritor’s argument is unsupported by either the text or the
    structure of the Hazard Ranking System.
    First, nothing in the text of the Hazard Ranking System
    expressly instructs the EPA to use site-specific exposure
    assumptions on the front end of the process when it is selecting
    the appropriate health benchmarks. The regulation, instead,
    instructs the EPA to use “health-based benchmarks” as set out
    in Table 5-20. 40 C.F.R. §§ 5.2.1.3.1, 5.2.1.3.2 & Table 5-20.
    That Table directs the EPA to consider both toxicological and
    carcinogenic benchmarks and, for cancer-related risks,
    establishes a one-in-a-million risk of cancer as the appropriate
    threshold.
    Id. The benchmark selection
    regulation thus makes
    no mention of site-specific characteristics, such as residential
    5
    The EPA found that the DCE and toluene concentrations in the
    main building did not exceed the selected residential benchmarks, so
    the choice between a residential and an industrial benchmark was of
    no consequence as to those substances.
    15
    or industrial use. Nor does it mandate that the EPA adopt any
    particular exposure assumptions.
    Second, the Hazard Ranking System accounts for the
    lower exposure faced by workers relative to full-time residents
    on the back end of its calculation. Once the occupants are
    sorted into either Level I or Level II, the EPA divides the
    number of people by three if they are full-time workers and by
    six if they are part-time workers. See 40 C.F.R. Part 300,
    App. A §§ 5.2.1.3.2.1, 5.2.1.3.2.2. This weighting accounts for
    the fact that full-time workers and part-time workers spend
    approximately one-third or one-sixth of the day at work
    respectively. UNITED STATES EPA, TECHNICAL SUPPORT
    DOCUMENT FOR U.S. EPA’S FINAL RULE: ADDITION OF A
    SUBSURFACE INTRUSION COMPONENT TO THE HAZARD
    RANKING SYSTEM 62 (2016) (“2016 TECHNICAL SUPPORT
    DOCUMENT”).
    So at bottom, because the Hazard Ranking System already
    accounts for the workers’ reduced hours of exposure relative to
    residents, the EPA reasonably relied on residential health
    exposure assumptions when selecting the appropriate health
    benchmarks. In fact, because the Hazard Ranking System
    requires those divisions by three or six regardless of which
    health benchmark is used, 40 C.F.R. Part 300, App. A
    §§ 5.2.1.3.2.1, 5.2.1.3.2.2, if the EPA had used an industrial
    health benchmark as Meritor proposes, it would have twice
    reduced the “targets” score based on worker status. Nothing in
    the Hazard Ranking System endorses, much less mandates,
    such double discounting.
    Beyond that, the EPA’s use of residential exposure
    assumptions is reasonable.
    For starters, when making listing decisions, the EPA
    uniformly uses residential exposure assumptions because it
    16
    favors a more “conservative (i.e. protective) approach[.]”
    J.A. 650. Erring on the side of caution in evaluating the
    toxigenic effects of hazardous substances on people is not
    unreasonable. See Board of Regents of the Univ. of Wash. v.
    EPA, 
    86 F.3d 1214
    , 1219 (D.C. Cir. 1996) (“It is not on its face
    unreasonable for the EPA to strike the balance by erring on the
    side of over-inclusion at the listing stage and on the side of
    under-inclusion at the remedial phase[.]”); see also Carus
    
    Chem., 395 F.3d at 441
    (The National Priorities List is meant
    to be a “rough list of priorities, assembled quickly and
    inexpensively.”) (internal quotation marks omitted).
    In addition, when selecting health benchmarks, the EPA
    generally uses uniform residential exposure assumptions
    across all sites and pathways. J.A. 648–650. That ensures that
    the Hazard Ranking System properly measures the “relative
    rather than absolute risk” of different hazardous waste sites in
    identifying the priority sites. 40 C.F.R. Part 300, App. A § 1.0;
    see also 42 U.S.C. § 9605(a)(8)(B) (National Priorities List is
    intended to identify sites that are a “priorit[y]” for remedial
    action).
    Finally, by using the more conservative benchmark, the
    agency accounts for both present and possible “future land-use
    conditions.” J.A. 650 (The EPA assumes “long-term/chronic
    exposures” because that is “the reasonable maximum
    exposure * * * expected to occur under both current and future
    land-use conditions.”).
    Because the EPA has reasonable policy reasons for
    starting out with a residential health benchmark, and its
    analysis properly adjusted the Rockwell Site’s score to account
    for workers’ reduced hours of exposure, the agency’s use of a
    residential health benchmark in calculating the “targets” score
    passes muster.
    17
    C
    Finally, Meritor argues that the EPA incorrectly calculated
    the “waste characteristics” component of the subsurface
    intrusion pathway. The “waste characteristics” score has two
    components: “toxicity/degradation” and “waste quantity.” 40
    C.F.R. Part 300, App. A §§ 2.4.2, 5.2.1.2. Meritor’s challenge
    aims at the latter—EPA’s measurement of the waste quantity.
    Meritor Br. 47–51.
    The Hazard Ranking System creates a tiered approach to
    calculating the quantity of waste in structures.
    Under Tier A, the EPA calculates the “mass of constituents
    found in [a] regularly occupied structure[] where [an] observed
    exposure has been identified.” 40 C.F.R. Part 300, App. A
    §§ 2.4.2.1.1, 5.2.1.2.2. If the EPA is able to estimate the
    quantity of waste under this method with “reasonable
    confidence,” the waste quantity inquiry ends there.
    Id. §§ 2.4.2.1.1, 2.4.2.1.2,
    5.2.1.2.2. If not, the EPA turns to
    Tier B.
    Under Tier B, the EPA must calculate the “flow-through
    volume” of the structure. 40 C.F.R. Part 300, App. A
    §§ 2.4.2.1.1, 2.4.2.1.2, 5.2.1.2.2. That is the amount of
    hazardous substances “that flows into the structure from the
    subsurface.” 2016 TECHNICAL SUPPORT 
    DOCUMENT, supra, at 42
    .
    If that computation proves infeasible, the EPA moves to
    Tier C, where it must estimate the volume of occupied portions
    of the structure. 40 C.F.R. Part 300, App. A §§ 2.4.2.1.3,
    5.2.1.2.2; see also 2016 TECHNICAL SUPPORT 
    DOCUMENT, supra, at 43
    . From this, the agency can estimate the “possible
    amount of hazardous substances” in occupied areas of the
    18
    building. See 2016 TECHNICAL SUPPORT 
    DOCUMENT, supra, at 41
    .
    And if all else fails, the EPA turns to Tier D, which allows
    the agency to derive a waste quantity score based on the
    structure’s floor area. 40 C.F.R. Part 300, App. A §§ 2.4.2.1.3,
    2.4.2.1.4, 5.2.1.2.2. The EPA applied Tier D to calculate the
    waste quantity in the Main Building at the Rockwell Site.
    Meritor claims that the EPA should have used Tier A to
    calculate waste quantity once the sub-slab depressurization
    system was installed. This was so, the company argues,
    because the sub-slab depressurization system ensured that the
    concentration of TCE, DCE, and toluene stayed within a
    narrow range. That, in turn, eliminated the high variance in
    concentrations that the EPA cited as an obstacle to calculating
    the mass of constituents with “reasonable confidence,” as
    Tier A requires. J.A. 35. Meritor also argues that the EPA
    erroneously stated that it needed air flow data to calculate the
    mass of hazardous substances under Tier A.
    Both of those arguments are forfeited because Meritor did
    not raise them before the EPA. The law is settled that those
    who challenge a National Priorities List placement “must
    present their claims clearly and specifically to the agency
    before raising them in a petition for review.” See CTS 
    Corp., 759 F.3d at 60
    (quoting Kent County v. EPA, 
    963 F.2d 391
    , 399
    (D.C. Cir. 1992)); see also Honeywell Int’l, Inc. v. EPA, 
    372 F.3d 441
    , 449, 451 (D.C. Cir. 2004); Linemaster 
    Switch, 938 F.2d at 1308
    .
    Meritor does not dispute its duty to present its challenges
    first to the EPA. It argues instead that it sufficiently raised its
    objection to the Tier D analysis by informing the agency that
    “it had violated rules ‘requiring EPA to consider an active
    vapor mitigation system * * * when calculating the hazardous
    19
    waste quantity.’” Reply Br. 24 (omission in original) (quoting
    J.A. 48 n.7); see also Oral Arg. Tr. 31:5–23.
    That argument, though, only advocated for consideration
    of the sub-slab depressurization system somewhere in the
    process of the “waste characteristics” analysis. It did not put
    the EPA on notice of Meritor’s specific objection to the tier
    used in the agency’s waste quantity analysis. See CTS 
    Corp., 759 F.3d at 60
    (“[P]arties opposing NPL listing must present
    their claims clearly and specifically to the agency before
    raising them in a petition for review.”); Carus 
    Chem., 395 F.3d at 441
    (Parties seeking to challenge agency action must first
    raise their objections with “reasonable specificity during the
    period for public comment[.]”) (internal quotation marks
    omitted).
    IV
    For all of those reasons, the petition for review is denied.
    So ordered.