SUFFOLK COUNTY WATER AUTHORITY v. THE DOW CHEMICAL COMPANY AND VIBRANTZ CORPORATION FORMERLY KNOWN AS FERRO CORPORATION (2026)

OPINION & ORDER

In this water contamination case, plaintiff Suffolk County Water Authority (“Suffolk”) brings suit against manufacturers Dow Chemical Company (“Dow”) and Vibrantz Corporation (“Ferro”). See Suffolk Cnty. Water Auth. v. Dow Chem. Co., 2025 WL 1907206 (E.D.N.Y. July 10, 2025). Suffolk contends that dioxane-stabilized TCA is the source of dioxane contamination in the TCA Claim Wells and offers the opinions of its expert witnesses in support. Dow rebuts this proof through the opinions of its own expert, Steve McGinnis. Suffolk moves to exclude a narrow subset of Mr. McGinnis's opinions. For the reasons set forth below, Suffolk's motion is granted.

I. Expert Qualifications

Steve McGinnis is a Managing Principal and practicing engineer at Ramboll US Consulting, Inc. (“Ramboll”). Expert Rebuttal Report of Steve McGinnis (“McGinnis Report”) at 2. He received a B.S. in Biological and Agricultural Engineering with a secondary major in Natural Resources and Environmental Science from Kansas State University. Id. He received a Masters of Engineering degree in Civil and Environmental Engineering from the Massachusetts Institute of Technology. Id. He is certified as a Professional Engineer in fifteen states, a Certified Groundwater Professional, a Board-Certified Environmental Engineer, and a Petroleum Release Remediator in South Dakota.

Mr. McGinnis has over twenty years of engineering experience “in the fields of environmental engineering, contaminated site investigation and remediation, contaminant fate and transport, and environmental forensics.” Id. He has consulted for numerous sites and facilities regarding contaminant releases, including in Suffolk County. Id. In his consulting experience, Mr. McGinnis has overseen site investigation and remediation efforts, including specific experience treating 1,4-dioxane and 1,1,1-TCA. Id.

The expert report at issue was prepared by Ramboll and signed by Mr. McGinnis.

II. The McGinnis Report

Mr. McGinnis issued an April 12, 2023 report rebutting the opinions of four of Suffolk's experts. He offers five opinions, the bulk of which Suffolk does not challenge. Relevant to the instant motion is Mr. McGinnis's Opinion 5, in which he opines that Suffolk's experts “failed to consider fully the implications of Suffolk County's unique and long-standing reliance on an archaic network of hundreds of thousands of cesspools and septic systems to discharge sanitary wastewater in the subsurface of Suffolk County on the loading of 1,4-dioxane to the SCWA claim wells from the everyday use of common consumer products, which have long contained 1,4-dioxane.” McGinnis Report at 30. After walking through the historical implications of Long Island's lack of sewering and longstanding reliance on a dense system of cesspools and septic systems, Mr. McGinnis explains that “[r]esidentially recharged contribution areas are known to consist of 1,4-dioxane sources due to everyday use of common, everyday consumer products.” Id. at 33. He then states that his “review of historical land use data confirms that the vast majority of claim wells (238 of 286) capture water from predominantly suburban residential areas” and opines that “the abundant suburban residential land uses in the contribution areas for these claim wells likely constitute a primary source of 1,4-dioxane due to the use and discharge of common, everyday consumer products containing 1,4-dioxane.”¹ Id.

Significantly, in an earlier section of his Report, Mr. McGinnis summarizes this opinion as follows: “[a]s discussed in Opinion 5, it is my opinion that 1,4-dioxane trends are more closely linked to the historical and ongoing use of consumer products containing 1,4-dioxane, rather than 1,1,1-TCA use.” Id. at 29.

Suffolk moves to exclude Mr. McGinnis's opinion that the use and discharge of consumer products in residential areas likely constitutes a primary source of 1,4-dioxane, as well as his opinion that 1,4-dioxane trends are more closely linked to consumer products rather than 1,1,1-TCA. It does not challenge the remainder of Opinion 5 or any other of Mr. McGinnis's opinions. April 30, 2026 Hr'g Tr. (“4/30 Tr.”) at 8:19-9:1.²

III. Discussion

The basic principles for the admission of expert evidence under Rule 702 of the Federal Rules of Evidence and Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579 (1993), are set forth in Suffolk Cnty., 2025 WL 1907206, at *2, and will not be repeated here.

Suffolk terms the two opinions it challenges as “source attribution opinions” and first argues that they should be excluded, because, at his deposition, Mr. McGinnis disavowed identifying the source of dioxane at any particular well. See McGinnis Dep. Tr. at 259:13-260:25. Dow responds that Mr. McGinnis never purported to identify the source of dioxane on a well-by-well basis. Rather, it argues, Mr. McGinnis merely pointed out that Suffolk's experts did not themselves “conduct the industry-standard, well-by-well analysis that is required to determine the actual origin of the 1,4-dioxane detected in each SCWA claim well,” citing McGinnis Report at 5. Mr. McGinnis testified at his deposition that he did not himself “make a [well-by-well] determination,” but merely “show[ed] that the data is there to do it on a well-by-well basis.” McGinnis Dep. Tr. at 260:4-16.

Indeed, Mr. McGinnis in his Report does not undertake a full source attribution analysis. He analyzes the historical use of the land where each TCA Claim Well is located from aerial photography and historical models from Suffolk and the United States Geological Survey. McGinnis Report at 33 n.14. He then classifies the land based on whether it is primarily residential, industrial, commercial, etc. Id. He concludes that 238 of the 286 Claim Wells capture water from residential areas, and he opines that this indicates that consumer products “likely constitute a primary source of 1,4-dioxane” in those Claim Wells. Id. at 33.

I agree with Suffolk that Mr. McGinnis's challenged opinions must be excluded for several reasons. First, it would mislead and confuse the jury to permit Mr. McGinnis to simultaneously opine that 1) a well-by-well analysis is required for a true source identification and 2) that consumer products are a “primary source” of dioxane in 238 wells without performing such a well-by-well analysis himself. It is permissible for Mr. McGinnis to opine that Suffolk's experts failed to properly account for the impact of Suffolk County's lack of sewering and the Claim Wells’ location on predominantly residential land. However, Mr. McGinnis cannot take the additional step of opining that consumer products are “likely” to be a “primary source” of dioxane in 238 wells while disavowing that he undertook a well-by-well analysis, which he opined was necessary to determine the source of dioxane in each well.³

Mr. McGinnis's land use analysis must also be excluded for another reason: he does not identify in his Report what analysis he used to classify each Claim Well's contribution area or whatever judgment he may have used to reach his conclusions. Indeed, the initial Report did not even contain a list of the 238 Claim Wells that Mr. McGinnis identified as capturing water “from predominantly suburban residential areas.” Rather, the Report provides in a footnote only a description of the various data sources Mr. McGinnis relied on, as well as links to the source files in an appendix. McGinnis Report at 33 n.14, App'x 6. Nowhere is Mr. McGinnis's “photointerpretation” of historical aerial photography, his analysis of the data source(s) he examined for each well, or his explanation of how he reconciled conflicting pieces of evidence set down in the initial Report. Following his deposition, and upon request from Suffolk, Mr. McGinnis provided a list of the 238 Claim Wells he determined were located in predominantly suburban residential contribution areas, but even then did not include any explanations as to how he determined this list. “Exclusion is required because the link, if any, between” the data Mr. McGinnis analyzed and his final land use conclusions “is written in invisible ink.” Open Text S.A. v. Box, Inc., 2015 WL 349197, at *6 (N.D. Cal. Jan. 23, 2015); see Suffolk Cnty., 2026 WL 799752, at *5.⁴

Finally, Mr. McGinnis's opinion that “1,4-dioxane trends are more closely linked to the historical and ongoing use of consumer products containing 1,4-dioxane, rather than 1,1,1-TCA use,” McGinnis Report at 29, must be excluded for yet another, independent reason. Namely, Mr. McGinnis never analyzes TCA as a source of the dioxane in the Claim Wells at all. Dow confirmed this at oral argument. 4/30 Tr. at 14:3-11. Mr. McGinnis thus provides no basis whatsoever to offer opinions on TCA as a source in the Claim Wells, let alone a basis for him to draw a conclusion that dioxane is “more closely linked” to consumer products than to TCA. Nowhere in the Report does he provide an explanation for this comparison. Rather, he simply expands his conclusory opinion that consumer products are a “primary source” of dioxane in 238 wells to a broad statement that rising dioxane trends are more closely linked to consumer products than to TCA. This is unacceptable under Rule 702.

IV. Conclusion

For the foregoing reasons, Defendants’ motion to exclude the opinions of Mr. McGinnis is GRANTED.

SO ORDERED.

FOOTNOTES

1.   The exact number of TCA Claim Wells in the case is the subject of a motion currently pending before the court. For the sake of this opinion only, I refer to the 286 wells Mr. McGinnis discusses in his Report.

2.   On March 23, 2026, I granted Suffolk's motion to exclude the well-by-well source identification opinions of John A. Connor and David T. Adamson, concluding that there was no well-by-well analysis in their expert report. See Suffolk Cnty. Water Auth. v. Dow Chem. Co., 2026 WL 799752 (E.D.N.Y. Mar. 23, 2026). Perhaps anticipating a similar outcome on this motion, the Defendants have sought to supplement both the Connor/Adamson and McGinnis Reports with well-by-well narratives, and Suffolk opposes the motion. The supplementation issue has been fully briefed by the parties and will be addressed in a separate opinion by the court. In this opinion, I address only the challenged opinions in Mr. McGinnis's original Report.

3.   Mr. McGinnis does not define a “primary source” in his Report. At oral argument, Dow was unable to point to anywhere that Mr. McGinnis explained the meaning of this term and suggested that it meant a “meaningful” contribution. 4/30 Tr. at 15:4-16:2. A jury could be misled by understanding a “primary source” to mean a principal or predominant source.

4.   My review of the well narratives with which Dow now seeks to supplement the McGinnis Report (see footnote 2 above) only confirms my conclusions. Each well narrative consists of multiple pages of textual explanation as to how Mr. McGinnis reached his land use classification for each Claim Well's contribution area, including which historical models he selected for analysis and specific features of each contribution area that he had to reconcile. Without addressing here whether his explanations are sufficient, suffice it to say those explanations and analysis could and should have been provided in the initial Report.

NINA GERSHON United States District Judge