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March 20, 2026 Get Citation Alerts Download PDF Add Note

Earl Parris, Jr. v. 3M Company, et al.

District Court, N.D. Georgia

• Citations: None known
• Docket Number: 4:21-cv-00040

• Precedential Status: Unknown Status

• Opinion

• Authorities (6)

• Cited By (0)

• Summaries (0)

• Similar Cases (2.2K)

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Trial Court Document

IN THE UNITED STATES DISTRICT COURT

FOR THE NORTHERN DISTRICT OF GEORGIA

ROME DIVISION

EARL PARRIS, JR.

Individually, and on behalf of a Class of

persons similarly situated,

 Plaintiff,                                                       

      v.                     CIVIL ACTION FILE                    
                             NO. 4:21-CV-40-TWT                   

3M COMPANY, et al.,

 Defendants.                                                      

               OPINION AND ORDER                                  

This is an action under the Clean Water Act. It is before the Court on
Defendants Daikin America, Inc., 3M Company, E.I. DuPont de Nemours, The
Chemours Company’s Motion to Exclude the Expert Testimony of Andrew

Stahl [Doc. 884]. For the reasons set forth below, the Court DENIES the
Defendants’ Motion to Exclude the Expert Testimony of Andrew Stahl
[Doc. 884].

I. Background

This case arises out of the contamination of surface waters and drinking
water in Chattooga County, Georgia, with per- and polyfluoroalkyl substances
known as “PFAS.” (2d Am. Compl. ¶ 1 [Doc. 280].) The facts of this case are
well known to the parties by this point, so the Court will not belabor them here.
In essence, Plaintiff Earl Parris, Jr., alleges that the Defendants have
contaminated his city’s water supply and thus his household water with PFAS.
Parris is a resident of Summerville, Georgia, who receives running, potable
water to his home from the Summerville Public Works and Utilities
Department. ( ¶ 21.) The City of Summerville, which has intervened in this

case, uses Raccoon Creek as the main source of its municipal water supply.
( ) The Court will collectively refer to Plaintiff Parris and Intervenor-Plaintiff
Summerville as the Plaintiffs. The Defendants are the following companies,
which allegedly manufactured and supplied the PFAS discharged into Raccoon
Creek: 3M Company, Daikin America, Inc., E.I. du Pont de Nemours and

Company, and The Chemours Company. At present, the Defendants jointly

move to exclude the expert witness testimony of Andrew Stahl. His testimony

concerns the source of PFAS in Raccoon Creek.

II. Legal Standard

Federal Rule of Evidence 702 governs the admissibility of expert
testimony. Under that rule, “expert testimony is admissible if (1) the expert is
qualified to testify regarding the subject of the testimony; (2) the expert’s
methodology is sufficiently reliable as determined by the sort of inquiry

mandated in ; and (3) the expert’s testimony will assist the trier of fact
in understanding the evidence or determining a fact at issue.”

, 766 F.3d 1296, 1304 (11th Cir. 2014) (citation
modified). Courts perform a “gatekeeping role” in excluding expert testimony
that does not satisfy these qualification, reliability, and helpfulness

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requirements. , 509 U.S. 579, 597 (1993).

“This gatekeeping role, however, is not intended to supplant the adversary
system or the role of the jury” in determining the persuasiveness of an expert’s

testimony. , 730 F.3d 1278, 1282 (11th Cir.

2013) (citation modified). Rather, the goal is to “make certain that an expert
. . . employs in the courtroom the same level of intellectual rigor that
characterizes the practice of an expert in the relevant field.”

, 387 F.3d 1244, 1260 (11th Cir. 2004) (en banc) (quoting

, 526 U.S. 137, 152 (1999)). “The proponent of the expert
testimony always bears the burden” of establishing qualification, reliability,

and helpfulness. (citation modified).

III. Discussion

Andrew Stahl is a licensed geologist employed by GEL Engineering,

LLC (“GEL”), as a senior hydrogeologist and project manager. (Defs.’ Mot. to
Exclude Stahl, Ex. 1 (Pt. 1) (“Stahl Report”),1 at 17 [Doc. 884-1].) He “has more
than 37 years of experience in environmental consulting, with areas of

expertise” that includes “groundwater, soil, PFAS, and vapor intrusion
contaminant investigations and remediations” and “industrial and municipal
facility and infrastructure environmental assessments and siting studies.” (

at 17.)

1 The pagination of this exhibit reflects the PDF pagination.

3

Per the Plaintiffs theory of the case, the Defendants’ PFAS was
discharged as wastewater to the Town of Trion’s Water Pollution Control
Plant, and the plant maintained a program by which it applied the treated but

still PFAS-laden wastewater to properties in the region, including farm
properties in the Raccoon Creek watershed. (2d Am. Compl. ¶¶ 1, 5, 36–37;
Stahl Report, at 8 (describing the Complaint’s allegations).) Stahl’s expert
report opines that PFAS-laden sludge applied to farms in the Raccoon Creek
watershed “has entered and is continuing to enter Raccoon Creek” through
identified transport pathways from certain PFAS-contaminated farms to
Raccoon Creek. (Stahl Report, at 11–12.) His opinion is supported by sampling

data collected from two areas (“Area 1” and “Area 2”) known to have received
sludge from Trion on farm properties owned by Lauren Jarrett. ( at 9.)
GEL collected samples on three occasions: (1) In January 2023,
“[f]ollowing a period of precipitation,” GEL collected surface water samples in
Areas 1 and 2 and at one upstream location. ( at 10.) (2) In September 2023,
“[d]uring drier conditions,” it collected soil and sediment samples in Areas 1

and 2, one groundwater sample at Area 1, two surface water samples at Area 1,
and two surface water samples at upstream locations. ( ) (3) In February
2024, it collected groundwater samples in Areas 1 and 2, surface water samples
in Areas 1 and 2, and surface water samples at upstream and downstream

locations. ( ) The Defendants challenge the reliability of Stahl’s testimony,

                        4                                         

arguing that his upstream, downstream, and groundwater data do not
adequately or reliably support his conclusions. The Court addresses each of
these arguments below. The Defendants do not challenge Stahl’s qualifications

or the helpfulness of his testimony to a trier of fact.

In determining whether an expert witness’s testimony is reliable under
Rule 702, the Court must evaluate “whether the reasoning or methodology
underlying the testimony is scientifically valid and . . . whether that reasoning
or methodology properly can be applied to the facts in issue.” , 509 U.S.
at 592–93. sets forth a number of factors relevant to this inquiry,
including (1) whether an expert’s theory or technique can be tested;

(2) whether the theory or technique has been subjected to peer review and
publication; (3) the known or potential rate of error of a scientific technique;
and (4) whether a known technique has achieved widespread acceptance in the
scientific community. at 593–94. These factors are not intended to be a
“definitive checklist,” at 593; rather, “the law grants the trial judge broad
latitude to determine . . . whether ’s specific factors are, or are not,

reasonable measures of reliability in a particular case.” , 526 U.S. at 153. Ultimately, the district court’s objective under is to
“make certain that an expert . . . employs in the courtroom the same level of
intellectual rigor that characterizes the practice of an expert in the relevant
field.” , 526 U.S. at 152. To this end, a district court may not admit

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opinions that “[are] connected to existing data only by the of the

expert” or leave “too great an analytical gap between the data and the opinion
proffered.” , 522 U.S. 136, 146 (1997).

A. Upstream Data

The Defendants contend that the upstream data samples “undercut[ ]”
Stahl’s “key assumption” that land-applied sludge is the only source of the
PFAS in Raccoon Creek. (Defs.’ Mot. to Exclude Stahl, at 3–4.) According to the
Defendants, PFAS was found in three samples located upstream of Jarrett
farms and all other farms where Trion’s sludge was applied, so it is not possible
to conclude that the sludge is the only PFAS contributor. ( at 5–7.)

The Plaintiffs respond that this “key assumption” is not in fact “the key,
or even a necessary, assumption or element of Mr. Stahl’s report.” (Pls.’ Resp.
Br. in Opp’n to Defs.’ Mot. to Exclude Stahl, at 7.) They explain that the
purpose of Stahl’s report was to “determine if the ‘environmental media
(surface water, groundwater, soil, and sediment) on the Jarrett’s property
where sludge had been applied provided transport pathways for PFAS

contamination from the property to enter Raccoon Creek.” ( at 7–8.)
Moreover, the Plaintiffs point out that Stahl addresses the three samples
identified by the Defendants and that he collected “dozens of other surface
water, groundwater, soil, and sediment samples” to support his “findings that
PFAS contamination from the[ ] sludge fields enters Raccoon Creek.” ( at

                        6                                         

10–11.)

The Court declines to exclude Stahl’s testimony on this upstream data
argument. As an initial matter, the Defendants’ arguments here are more

appropriate for cross-examination than a motion to exclude, as they concern
Stahl’s interpretation of the data samples and not a problem with Stahl’s data
collection process. , 730 F.3d at 1282 (noting that Rule 702

“is not intended to supplant . . . vigorous cross-examination,” which is a central
part of “the adversary system” and “the role of the jury”). Even considering the
merits of the Defendants’ concerns, the Court finds them unpersuasive for at
least two reasons.

First, the Defendants have overstated the relevance of one line in Stahl’s
report. In his conclusion section, Stahl opines that “PFAS that was contained
in the sludge applied to sludge application fields has entered and is continuing
to enter Raccoon Creek.” (Stahl Report, at 11–12.) He then describes the
various “transport pathway[s]” through which PFAS-laden sludge has made
its way to Raccoon Creek. ( at 12.) These pathways form the bulk of his

opinion, which is consistent with the stated purpose of Stahl’s report.2 The
first page of Stahl’s report outlines its purpose and scope: “The objective of the

2 That is, they form the bulk of “Opinion Statement 2,” which is the
opinion relevant here. There are two opinion statements. “Opinion
Statement 1” merely states that the sampling results “can be relied upon with
a high degree of confidence” and describes GEL’s professional sampling
practices. (Stahl Report, at 11.)

7

environmental media evaluations was to assess PFAS transport pathways

from the sludge application fields to assess if PFAS contained in the land-
applied sludge has, and is continuing to, enter Raccoon Creek.” ( at 8.) In

their briefing, the Defendants seize only on the last line in Stahl’s conclusion
section, which notes the following: “Based upon a review of state and federal
regulatory information and our visual survey of the Raccoon Creek watershed
upstream of the City of Summerville’s drinking water intake, there are no
other known sources of PFAS in the Raccoon Creek watershed other than the
Trion sludge application on farm fields in the Raccoon Creek watershed.” (

at 12.) This final line is a note about the lack of awareness of other “

sources of PFAS.” ( (emphasis added).) It is entirely consistent with the
rest of Stahl’s report and conclusions, and it would be consistent with the fact
that some samples suggest potential sources of PFAS.

Second, the fact that three of Stahl’s samples indicate PFAS
concentrations upstream of farms where sludge was applied does not
automatically mean that Stahl’s conclusions are unfounded. Stahl has

collected a number of upstream samples3 and concluded from those and other

3 The Court does not attempt to count the number of upstream surface
water samples but notes that several of them appear to be listed in Tables 5
and 6 of Stahl’s report. ( Defs.’ Mot. to Exclude Stahl, Ex. 1 (Pt. 2), at 7–8
[Doc. 884-2]; Stahl Report, at 33–34 (describing the upstream surface
water data).) As Stahl notes in his rebuttal report, GEL collected and analyzed
“29 soil, 8 sediment, 33 surface water, and 7 groundwater samples (excluding
quality control samples).” (Pls.’ Resp. Br. in Opp’n to Defs.’ Mot. to Exclude,
8

samples that transport pathways from the Jarrett properties to Raccoon Creek
have allowed PFAS from the land-applied sludge to enter Raccoon Creek. (

at 40–41, 12.) Moreover, Stahl specifically addressed the three samples that

the Defendants identified, stating that “[s]urface water PFAS contamination
upstream of Jarrett properties sludge application fields Areas 1 and 2 may be
attributed to these additional land application properties and/or other
potential currently unknown land-application parcels within the headwaters
of the Raccoon Creek drainage basin. ( at 41.) For these reasons, the Court
finds Stahl’s opinions sufficiently supported under and Rule 702 with
respect to his analysis of the upstream data.4

B. Downstream Data

The Defendants argue that downstream samples also undercut Stahl’s

Ex. 2 (“Stahl Rebuttal Report”), at 4 [Doc. 968-4].) The pagination of Exhibit 2
of the Plaintiffs’ response brief reflects the PDF pagination.

4 The Defendants make much of a 2023 amendment to Rule 702 in their
reply brief. They explain that courts must find an expert’s opinions reliable
and based on sufficient facts by a preponderance of the evidence. (Reply Br. in
Supp. of Defs.’ Mot. to Exclude Stahl, at 2–3 [Doc. 1001].) The Court does so
when it holds here and elsewhere that Stahl’s opinions are “sufficiently”
supported under and Rule 702.

The Court notes that Rule 702 was amended “to clarify and emphasize
(1) the applicability of the preponderance of the evidence standard, that is,
expert testimony may not be admitted unless the proponent demonstrates to
the court that it is more likely than not that the proffered testimony meets the
admissibility requirements set forth in FRE 702, and (2) that each expert
opinion must stay within the bounds of what can be concluded from a reliable
application of the expert's basis and methodology.”

, 740 F. Supp. 3d 1172, 1178 n.3 (N.D. Fla. 2024) (citation
modified).

9

conclusion. If Stahl’s conclusion about PFAS-laden sludge is correct, samples
downstream of the farms should show PFAS concentrations “‘decreas[ing] in
the downstream direction’ due to ‘dilution’ as the PFAS gets further away from

its source.” (Defs.’ Mot. to Exclude Stahl, at 9 (quoting Stahl Report,5 at 41).)
But the Defendants point out two downstream samples that show the
opposition relationship since the sample further downstream had a higher
PFAS concentration than the other. ( at 9–11.)

The Court declines to exclude Stahl’s testimony on these grounds. Once
again, the Defendants’ arguments are better suited for cross-examination and
the presentation of contrary evidence than an admissibility challenge. The

Defendants take issue with only two of Stahl’s myriad samples, whereas Stahl
made his determinations from an evaluation of all the samples. The report
states: “Total PFAS concentrations measured in samples collected from
Raccoon Creek decrease in the downstream direction. Undoubtedly, this is due
to dilution from less-contaminated or non-contaminated tributaries.” (Stahl
Report, at 41; at 41–42 (mentioning other samples on which Stahl

relied).) Moreover, Stahl’s report addresses the two samples at issue,
suggesting that, while further testing is necessary, “the highly contaminated
groundwater . . . likely discharges” to an area upstream of where the two

5 The Defendants cite page thirty-four of Stahl’s report, which is
page forty-one in the PDF document.

10

samples of high PFAS concentrations were collected. ( at 42.) The
Defendants call this statement mere speculation, (Reply Br. in Supp. of Defs.’
Mot. to Exclude Stahl, at 8–9), but the Court is satisfied with Stahl’s overall

assessment of the data and discussion of potential outlier data for

purposes.

C. Groundwater Data

As to Stahl’s groundwater data, the Defendants claim that GEL did not
use a reliable sampling methodology, as his samples did not comply with the
EPA’s “Groundwater Sampling Operating Procedure.” (Defs.’ Mot. to Exclude
Stahl, at 14–15.) The EPA manual considers the “purging” aspect of

groundwater sampling “adequate” when the samples are collected from water
below 10 Nephelometric Turbidity Units (“NTUs”). U.S. EPA, Region 4,
15 (2013) (hereafter “EPA

Region 4 Groundwater Operating Procedure”) (available at

https://tinyurl.com/3kbs6e6w); at 13 (“Purging is the process of

removing stagnant water from a well, immediately prior to sampling, causing

its replacement by groundwater from the adjacent formation that is
representative of actual aquifer condition.”). But, according to the Defendants,
“Stahl’s groundwater samples had sky-high turbidity readings—ranging from
439 NTUs, to 740 NTUs, and in many cases over 1,000 NTUs.” (Defs.’ Mot. to
Exclude Stahl, at 15.) The Defendants contend that the high turbidity renders

                       11                                         

the samples potentially biased because they “cannot accurately isolate a
measurement for PFAS ” as opposed to

“undissolved PFAS in the mud . . . [that] will not migrate to Raccoon Creek.”

( at 16.)

The Court declines to exclude Stahl’s testimony for high turbidity.
Stahl’s report notes that sampling was conducted “in accordance with usual
and customary profession practices” and goes on to explain those practices in
some depth. (Stahl Report, at 11, 30–31.) His rebuttal report further outlines
the sampling methodology conducted and why it aligns with industry practice.
(Stahl Rebuttal Report, at 5.)6 As the Court is no expert on groundwater

sampling, the Court excerpts his explanation below:

The completed groundwater sampling program was conducted

using direct-push drilling technology for point-in-time

groundwater sampling in part because landowner permission was

not granted to install and extensively develop permanent

monitoring wells. Direct-push drilling with point-in-time

groundwater sampling has been recognized for decades as a usual

and customary professional practice for site reconnaissance/site

characterization such as that conducted for the Jarrett Properties
Sludge Application Fields assessment. This usual-and-customary

recognition is acknowledged by the United States Environmental

Protection Agency (EPA) in the August 2005 guidance document,

, OSWER No. 9200.1-51, EPA 540/R-04/005. In this

document, EPA discusses various techniques to collect

groundwater samples by advancing direct-push drilling rods . . . .
The methodology employed by GEL to conduct the site

reconnaissance/site characterization at the Jarrett Properties
Sludge Application Fields was a hybrid of and an upgrade to the

6 The pagination of this exhibit reflects the PDF pagination.

12

EPA-referenced techniques listed above selected.

                                       .  . . .  These            

methodologies are, in fact, recognized as usual and customary

professional practices.

( at 5 (emphasis added).) Stahl goes on to state that his analysis remains
sound “[d]espite the presence of turbidity.” ( (“Despite the presence of
turbidity . . . , the laboratory analytical results clearly demonstrate that
shallow groundwater is contaminated from PFAS that leached to the water
table through contaminated soils across Jarrett properties sludge application
fields.”).) Considering Stahl’s explanation, qualifications, and experience, the
Court is satisfied that Stahl has “employ[ed] in the courtroom the same level
of intellectual rigor that characterizes the practice of an expert in the relevant
field.” , 526 U.S. at 152. Thus, his groundwater sampling methodology
is reliable under and Rule 702.

The Defendants’ mere citation to an EPA manual about turbidity does

not by itself show that Stahl’s methodology is unreliable. For example, the EPA
manual on which the Defendants rely states that turbidity lower than 10 NTUs
“has been shown to be easily achievable in most situations and reasonable
attempts should be made to achieve these lower levels.” EPA Region 4
Groundwater Operating Procedure, at 15. The Defendants rely on this
13

statement to demonstrate that Stahl’s data sampling was improper. But
Stahl’s rebuttal report suggests that low turbidity ratings were not possible at
the time and that GEL made reasonable attempts to ensure high quality
samples. The Defendants have not shown that taking low turbidity samples is
possible at these sites. Moreover, they have not established that EPA guidance
requires low turbidity to qualify data as reliable nor that the “operating
procedure” for EPA Region 4 is the only reliable method of collecting data
samples. If the Defendants wish to point out the high turbidity ratings, they
may do so on cross examination and present evidence as to why that may bias
the samples and to what degree. The Court denies the Defendants’ Motion to
Exclude as to Stahl’s groundwater methodology.
IV. Conclusion
For the reasons set forth above, the Court DENIES Defendants Daikin
America, Inc., 3M Company, E.I. DuPont de Nemours, The Chemours
Company’s Motion to Exclude the Expert Testimony of Andrew Stahl
[Doc. 884].
SO ORDERED, this _ 20th day of March, 2026.

                                    THOMAS W. THRASH, JR. 
                                    United States District Judge 

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