                           In the

United States Court of Appeals
              For the Seventh Circuit

No. 11-2427

KS E NERGY S ERVICES, LLC,
                                                       Petitioner,
                               v.

H ILDA L. S OLIS, Secretary of Labor,
                                                     Respondent.


                Petition for Review of an Order of
      the Occupational Safety and Health Review Commission.
                            No. 09-1272


    A RGUED A PRIL 17, 2012 — D ECIDED D ECEMBER 13, 2012




  Before B AUER, K ANNE, and SYKES, Circuit Judges.
  S YKES, Circuit Judge. While installing a natural-gas
pipeline in Madison, Wisconsin, KS Energy Services,
LLC, was cited by the Occupational Safety and Health
Administration (“OSHA”) for violating trench safety
regulations that require companies to protect workers from
dangerous cave-ins. After inspecting KS Energy’s
trench, OSHA issued a citation alleging a repeat violation
of 29 C.F.R. § 1926.652(a)(1) for failing to provide
an adequate protective system. KS Energy contested the
citation, but an ALJ upheld it on two independent grounds:
2                                               No. 11-2427

(1) the soil in KS Energy’s trench was classified as
“Type B,” and therefore the slope of the trench was
too steep based on the OSHA inspector’s calculations;
and (2) KS Energy improperly used the technique of
“benching” to configure its trench, violating applicable
trenching regulations. The ALJ imposed a monetary
penalty for the safety violation. The Occupational
Safety and Health Review Commission (“OSHRC”) initially
directed a review of the ALJ’s determination, but later
vacated that decision, making the ALJ’s determination
final. KS Energy petitioned this court for review.
  We deny the petition. The parties agree that if the soil in
the excavation was properly classified as Type B, the
trench was impermissibly steep. Substantial evidence
supports the ALJ’s determination that the soil was classi-
fied as Type B. KS Energy also challenges the ALJ’s deter-
mination that the trench was improperly configured,
arguing that the agency’s interpretation of the trenching
regulations is unreasonable and unconstitutionally vague.
Because the soil-classification decision is an independent
ground for the ALJ’s decision and adequately supported by
the record, we need not address this alternative argument.


                      I. Background
  KS Energy is based in New Berlin, Wisconsin, and
provides excavation, construction, and related technical
services to the natural gas, electric, and telecommunica-
tions industries. On June 10, 2009, KS Energy was installing
a natural-gas pipeline along an 8-to-10-block span of
University Avenue, a main thoroughfare in Madison,
Wisconsin. Late that afternoon OSHA Compliance Officer
No. 11-2427                                                3

Kimberly Morton arrived at the site and took several
measurements of KS Energy’s excavation using a trench
pole—an engineering rod used to determine the angle of
trench slopes. OSHA regulations specify the maximum
allowable pitch of a trench slope based on the classification
of the soil type in the excavation. Officer Morton took
three slope measurements at different locations in the
trench yielding angles of 46, 50, and 46 degrees.
  Morton also observed several conditions near
her measurement sites that could potentially affect the
soil classification under OSHA regulations. For example,
she noted a small amount of water in several footprints
at the base of the trench, raising a concern that the trench
soil might be destabilized by the presence of water.
She also noticed existing utility lines alongside the excava-
tion, suggesting the possibility that the soil had
been previously disturbed, another factor calling for a
downgrade in soil type. Finally, Morton noted the potential
for destabilizing vibration due to steady automobile traffic
along University Avenue and the use of a backhoe along-
side the trench. Unsure of whether the construction
site was in compliance with OSHA regulations, Morton
reported her findings to her supervisor Chad Greenwood,
who instructed her to return the following day with
Nick Kerkenbush, a more experienced excavation inspec-
tor. Morton and Kerkenbush went back to the site on
June 11. Kerkenbush took soil samples with a shovel
from the side of the trench a few feet down but did not
take samples closer to the bottom of the trench.
 The point of this inspection was to determine whether KS
Energy was in compliance with 29 C.F.R. § 1926.652(a)(1),
4                                                    No. 11-2427

which requires construction employers to protect employ-
ees in an excavation by using an adequate protective
system designed in accordance with subsection (b) or
(c) of § 1926.652. Under § 1926.652(b) employers may
elect to either slope or “bench 1 ” the sides of the
excavation at appropriate angles based on soil classifica-
tions and other factors.2 Appendices A and B to Subpart
P of § 1926 prescribe the permissible slope angles
and configurations for sloping and benching systems.
29 C.F.R. § 1926.652(b)(2). Appendix A explains the
various soil classifications that determ ine the
allowable slopes. The soil classifications are listed
by cohesiveness in descending order of stability:
Stable Rock, Type A, Type B, or Type C. Id. § 1926, subpt.
P, app. A(b).
  The initial soil classification is subject to downgrading
based on various factors that affect soil stability and
thus employee safety. As pertinent here, Appendix A
states:
    [N]o soil [may be classified as] Type A if:
    (i) The soil is fissured; or


1
   Sloping is “excavating to form sides of an excavation that are
inclined away from the excavation.” 29 C.F.R. § 1926.650(b).
Benching is “excavating the sides of an excavation to form one
or a series of horizontal levels or steps, usually with vertical or
near-vertical surfaces between levels.” Id.
2
   Under § 1926.652(c) an employer can also fulfill its safety
obligations by using supports, shields, or other protective
systems.
No. 11-2427                                               5

   (ii) The soil is subject to vibration from heavy traffic,
   pile driving, or similar effects; or
   (iii) The soil has been previously disturbed; or
   ....
   (v) The material is subject to other factors that would
   require it to be classified as a less stable material.
Id. Soil is also presumptively classified as Type C if it
is “[s]ubmerged soil or soil from which water is freely
seeping.” Id. A “layered system” of soil is defined as
“two or more distinctly different soil or rock types ar-
ranged in layers.” Id. In a layered system, the soil
is classified by its weakest layer, or “each layer may
be classified individually where a more stable layer
lies under a less stable layer.” Id. § 1926, subpt. P, app.
A(c)(4). For every excavation a competent person
must classify the soil according to the definitions
in Appendix A based on visual and manual tests. Id.
§ 1926, subpt. P, app. A(c)(1)-(2).
  Based on the tests conducted by Morton
and Kerkenbush, OSHA determined that the soil in the
KS Energy trench was Type B, which corresponds to
a maximum allowable slope of 45 degrees. Id. § 1926,
subpt. P, app. B, tbl.B-1. This meant the trench was out
of regulatory compliance based on Morton’s slope mea-
surements of 46, 50, and 46 degrees. Accordingly,
OSHA issued KS Energy a citation for a repeat violation
of § 1926.652(a)(1). KS Energy contested the citation
and proceeded to trial before an ALJ. Based primarily
on the testimony of its expert Harry Butler, KS Energy
6                                                No. 11-2427

argued that the soil in the bottom part of the trench should
be classified as Type A, and therefore the trench slope
was within the corresponding maximum allowable slope
of 53 degrees. See id.
  The ALJ upheld the citation, resting his decision on
two alternative grounds. First, the ALJ concluded that
the soil in the entire trench was properly classified as
Type B soil, meaning that KS Energy violated
§ 1926.652(a) given Morton’s slope measurements,
which KS Energy did not dispute. Second, the ALJ ac-
cepted the Secretary of Labor’s interpretation that
§ 1926.652(b) and Appendices A and B prohibit “benching”
in “layered soils,” an independent ground for the cita-
tion. The ALJ found KS Energy in violation of § 1926.652(a)
and imposed a penalty of $12,500. Although the OSHRC
initially directed review of the ALJ’s determination, it later
vacated that decision, making the ALJ’s determination
final. KS Energy timely filed a petition for review.


                      II. Discussion
   “The findings of the [Occupational Safety and Health
Review] Commission with respect to questions of fact,
if supported by substantial evidence on the record consid-
ered as a whole, shall be conclusive.” 29 U.S.C.
§ 660(a). Where, as here, the OSHRC does not direct
review of an ALJ’s decision, the ALJ’s findings become
the Commission’s, and the substantial-evidence standard
“applies with undiminished force.” P. Gioioso & Sons,
Inc. v. OSHRC, 115 F.3d 100, 104 n.3, 108 (1st Cir. 1997);
see also Union Tank Car Co. v. OSHA, 192 F.3d 701, 704-
No. 11-2427                                                7

05 (7th Cir. 1999) (applying substantial-evidence standard
where the OSHRC did not direct review of the
ALJ’s decision). “Substantial” in this context “does
not mean a large or considerable amount of evidence,
but rather such relevant evidence as a reasonable
mind might accept as adequate to support a conclusion.”
Pierce v. Underwood, 487 U.S. 552, 565 (1988) (internal
quotation marks omitted). The agency must also “ ‘build
an accurate and logical bridge between the evidence
and the result.’ ” Chao v. Gunite Corp., 442 F.3d 550, 558
(7th Cir. 2006) (quoting J.C. Penney Co. v. NLRB, 123
F.3d 988, 995 (7th Cir. 1997)).
  As we have noted, the ALJ upheld the citation on
two separate grounds, the first based on the soil classifica-
tion (and its effect on the allowable slope in the trench)
and the second based on the agency’s interpretation of
the applicable regulations regarding benching in layered
soils. On the first ground, KS Energy had agreed that if
the entire excavation involved Type B soil, then the
trench slope was too steep and in violation of OSHA
regulations. KS Energy conceded that the soil in the
upper part of the trench was Type B; the factual
dispute before the ALJ thus centered on the proper classifi-
cation of the soil in the lower portion of the excavation.
  KS Energy argues that the only reliable evidence regard-
ing the soil classification in the lower portion of
the excavation came from its expert Harry Butler.
Unlike Morton and Kerkenbush, Butler actually went
into the trench, took soil samples, and measured the
soil’s compression strength. Butler therefore was the
8                                               No. 11-2427

only one who conducted soil tests in the lower part of
the excavation, and he concluded that it contained Type
A soil from a depth of 32 inches to the bottom of the
trench.
  The ALJ concluded, however, that any soil in the trench
initially testing as Type A “should have been downgraded
to at least Type B soil” based on several factors listed in
the applicable regulations that affect soil-classification
determinations. See 29 C.F.R. § 1926, subpt. P,
app. A(b). More specifically, the ALJ found that “the soil
in the excavation was subject to vibrations from traffic
and [the use of a] backhoe, contained increasing amounts
of water from an unknown source, and was previously
disturbed at multiple locations in the trench.” Substantial
evidence supports at least two of these findings, either
of which is enough to support the ALJ’s decision.


A. Soil Subject to Vibration
  To repeat, OSHA regulations provide that no soil may
be classified as Type A if it is “subject to vibration from
heavy traffic, pile driving, or similar effects.” Id. The
ALJ found that notwithstanding the results of Butler’s
tests, the soil in the excavation could not be classified
as Type A because it was subject to vibration. The sources
of vibration, the ALJ found, included the “two lanes
of heavy vehicular traffic running parallel to the excavation
approximately twelve feet from the excavation edge”
and “the operation of a large, tracked backhoe along
the length and edge of the excavation.”
No. 11-2427                                                  9

  KS Energy argues that Morton, Kerkenbush, and Butler
did not report feeling any vibration in the trench
during their inspections. But the relevant standard
is whether the soil “is subject to vibration from
heavy traffic, pile driving, or similar effects.” Id. (emphasis
added). Morton testified about the steady traffic
on University Avenue on June 10, 2009, roughly 12
feet from the excavation. Kerkenbush described University
Avenue as a “major throughway,” and no one disputes
this characterization. This evidence is enough to
support the ALJ’s finding that the soil in the trench
was subject to vibration and therefore could not be classi-
fied as Type A. Evidence of actual vibration is not neces-
sary.
  With respect to the ALJ’s reliance on the operation of
a large tracked backhoe near the excavation, KS
Energy argues that the use of heavy equipment near
the excavation site cannot itself be sufficient to
downgrade Type A soil to Type B because this kind
of equipment is always used to dig construction
trenches. Whatever force that argument has as a general
matter, here the ALJ found that KS Energy was operating
a large tracked backhoe along the length and near the
edge of the trench, which when combined with the
heavy traffic on University Avenue made the soil subject
to destabilization due to vibration. We need not consider
whether the use of the backhoe alone would satisfy
the “subject to vibration” standard.
10                                              No. 11-2427

B. Previously Disturbed Soil
  OSHA regulations also provide that no soil may
be classified as Type A if it has been “previously dis-
turbed.” 29 C.F.R. § 1926, subpt. P, app. A(b). The
ALJ applied this provision based on a finding that
four previously installed utility lines ran perpendicular
to the excavation in areas where KS Energy crews
were working. KS Energy points out that the OSHA
inspectors could not determine the precise extent
of the previously disturbed soil. For example, Morton
testified that she did not investigate and did not
know where the disturbed soil around the utility
lines began and ended. She did testify, however, that KS
Energy’s employees were working approximately eight
to ten feet from at least one utility line. Kerkenbush
testified that several areas around the utility lines con-
tained previously disturbed soil but could only speculate
as to how far that area extended. Butler testified that
a utility pipe passing through the excavation was located
well above the bottom bench of the trench (three to three-
and-a-half feet below grade) and that only the soil immedi-
ately adjacent to the pipe had been previously disturbed.
  KS Energy’s argument boils down to a claim that
the evidence did not establish how much of the soil
was previously disturbed by the prior installation of
other utilities. The substantial-evidence standard is not so
exacting. That the evidence is not more precise on
this point does not undermine the ALJ’s decision; the
ALJ was entitled to credit the inspectors’ general testimony
about the nearby utility lines. Moreover, the testimony
No. 11-2427                                                11

of OSHA supervisor Chad Greenwood corroborated the
testimony of the inspectors; he explained that when
installing utility lines, contractors typically “open up the
trenches . . . so they have room to work.” Finally, the
ALJ heard testimony from KS Energy’s safety director
Joshua Retzleff about the water pipe at the east end of
the trench, approximately three to four feet from the
bottom, which places the previously disturbed soil within
the bottom 52 to 70 inches of the trench, where Butler’s
testing found Type A soil. The cumulative effect of
this testimony supports the ALJ’s finding that the soil in
the trench had been previously disturbed and therefore
could not be classified as Type A.


C. Water in the Trench
   The ALJ also relied on the presence of “increasing
amounts of water from an unknown source” to downgrade
the soil type in the bottom of the trench. OSHA regulations
classify “[s]ubmerged soil or soil from which water
is freely seeping” as Type C soil. 29 C.F.R. § 1926, subpt. P,
app. A(b). We question whether the evidence is sufficient
on this factor. Although Morton observed some
water accumulating in footprints at the bottom of
the trench on June 10, 2009, she did not testify that
there was “submerged” soil or “freely seeping water” in
the trench. The presence of water in the footprints
may have been enough to alert Morton, Kerkenbush,
and Greenwood to investigate further, but it seems insuffi-
cient without more to justify downgrading the soil classifi-
cation based on “submerged soil or soil from which water
is freely seeping.”
12                                             No. 11-2427

  In the end, whether the evidence supports the ALJ’s
decision on this point does not matter because substantial
evidence supports his determination that the soil was
at best Type B because it was subject to vibration and
had been previously disturbed. As such, the trench ex-
ceeded the maximum allowable slope.
  Because substantial evidence supports the ALJ’s decision
based on the soil classification alone—an independent
basis for the citation—we need not address KS Energy’s
challenge to the ALJ’s separate determination regarding
the benching configuration in the trench. Accordingly, we
do not reach KS Energy’s argument that the agency’s
interpretation of the trenching regulations is unreasonable
and unconstitutionally vague.
 The petition for review is D ENIED.




                          12-13-12
