In this water contamination case, Defendants Dow Chemical Company and Vibrantz Corporation (collectively, “Defendants”) challenge the proof which Plaintiff Suffolk County Water Authority (“Suffolk”) proffers through its expert witnesses that dioxane-stabilized TCA is the source of the contaminant 1,4-dioxane in what it calls the TCA Claim Wells.
Defendants did so through the opinions of their own expert witnesses John A. Connor and David T. Adamson. Suffolk did not challenge the bulk of the Connor/Adamson opinions, which are rebuttals to Suffolk’s experts. Rather, Suffolk filed a motion to exclude one subset of those opinions, namely, those opinions which affirmatively assert well-by-well conclusions as to source identification of the 1,4-dioxane in the wells.
Environmental Engineering Expert Witnesses
John A. Connor has over forty years of experience in environmental engineering, including specialization in “environmental site investigation, human health and ecological risk assessment, corrective action design, water resource development and remediation, and design and permitting of treatment facilities.”
He received an M.S. in Civil Engineering from Stanford University and is a registered Professional Engineer, a licensed Professional Geoscientist, and a Diplomate in the American Academy of Environmental Engineering.
David T. Adamson received his Ph.D. in Civil and Environmental Engineering from the University of Iowa and has over twenty-two years of research and environmental consulting experience. He has conducted research and authored technical articles on a wide range of topics related to subsurface contamination, including serving as Principal or co-Principal Investigator on research projects sponsored by the U.S. Department of Defense on topics such as 1,4-dioxane fate, transport, and treatment. Adamson has also consulted on a broad range of topics, including “chemical fate and transport, site investigation, remedy screening, risk assessment, remedial design, drinking water distribution, and litigation matters.”
Discussion by the Court
II. The Connor/Adamson Report
Connor and Adamson opined that TCA is the source of the 1,4-dioxane in only a small fraction of the TCA Claim Wells. Rather, they asserted, that the predominant source is septic system and wastewater releases. This conclusion appears in Section 3.3 of their Report, which consisted of pages 70-76 out of 160 pages, plus a mass of appended charts. Connor and Adamson opined that they identified ten relevant “lines of evidence” and that they used a “weight-of-evidence” methodology to assess the likely source of 1,4-dioxane in each of the TCA Claim Wells.
The lines of evidence include, for example, TCA detections in each well, and land use within the capture zone. Section 3.3 contains an explanation of the lines of evidence as well as the experts’ ultimate conclusions that the weight of the evidence is consistent with a septic system and wastewater source of 1,4-dioxane in the vast majority of well fields containing TCA Claim Wells.
Upon review of the Connor/Adamson Report and the appended charts, the Court found that there was in fact no well-by-well analysis in the report or in the charts.
In the Report, Connor and Adamson did not assign numeric weight to the various lines of evidence or follow a decision tree to reach an ultimate conclusion.
Analysis
Defendants acknowledged that Section 3.3 contains only (1) a discussion of the ten lines of evidence and (2) Connor and Adamson’s ultimate conclusions as to the likely source of 1,4-dioxane in each of the TCA Claim Wells.
Indeed, review of these appendices reveals a complete absence of analysis as to how the experts reached those final conclusions. Put another way, it is impossible to glean what the experts’ thought processes were in considering the cumulative effect of the thousands of data points that make up the purported “full form” well-by-well analysis.
The Court rejected Defendants’ argument that the detailed narratives through which the experts intended to present their testimony, which they estimate could take up to three hours per well, can be discerned merely by looking at the charts. On the contrary, it is clear that Defendants intended to use the trial testimony to supply the missing explanations as to how each line of evidence factored into the ultimate conclusion as to each well.
Indeed, if the charts themselves were a sufficient basis for understanding the experts’ reasoning in reaching their ultimate source identification conclusions, as the Defendants contended, then—after the experts’ general testimony applicable to all wells—the Defendants would need only to present the charts to the jury.
There is no way for the Court to evaluate whether the methods the experts used or the judgment they applied was reliable or not. As an example of why this is important, consider the undisputed fact that, with respect to some wells, the experts’ lines of evidence point to inconsistent or conflicting results as to the source of the 1,4 dioxane. Nowhere did the experts provide any analysis of how they resolved—or can resolve—such inconsistencies or conflicts. Rather, it is clear that their application of judgment is separate for each well, yet no effort has been made in the Report to set forth how those individual judgments were made.
Finally, Defendants’ suggestion that they can have their experts describe in narrative form how they reached their source identification conclusions well-by-well for the first time at the trial, without having provided their analyses pre-trial, violated fundamental principles of pre-trial expert discovery.
Held
The Court granted Suffolk’s motion to exclude John Connor and David Adamson’s well-by-well assessment of dioxane sources.
Key Takeaway
The question is not simply whether Connor and Adamson may consider various lines of evidence together in reaching a conclusion. Rather, as explained above, the problem is that their Report does not present any analysis of how the various lines of evidence led them to their ultimate conclusions. In these circumstances, the Court is unable to determine the reasoned bases for Connor and Adamson’s analysis and whether it is truly reliable “at every step.”
Case Details:
| Case Caption: | Suffolk County Water Authority V. The Dow Chemical Company |
| Docket Number: | 2:17cv6980 |
| Court Name: | United States District Court, New York Eastern |
| Order Date: | March 23, 2026 |
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