Fate & Transport

Defense of Groundwater Contamination Claims

Jon Rohrer, P.G., C.Hg.


Roux Associates helped defend a major furniture manufacturing company against claims brought by a water agency plaintiff for environmental damages. The primary issues in the case centered on past chemical use, release timing, commingling and impacts to groundwater.

As part of a vigorous and thorough defense, Roux identified significant use of chemicals at issue for a settling defendant across the street and co-mingling which was overlooked and minimized by the Plaintiff. On a regional scale, Roux Associates: (1) documented and evaluated the plaintiff’s own injection of 1,4-dioxane directly into the aquifer (as part of a recycled water program) in light of, (a) the plaintiff’s asserted “cleanup standard” for 1,4-dioxane and (b) the plaintiff’s alleged bases for damages claimed against defendants for 1,4-dioxane groundwater impacts; (2) documented the hydrogeologic implausibility of deep aquifer (and drinking water well) impacts from the client’s site; and, (3) established the Client’s compliance with all pertinent state regulatory directives. The Court ruled for the defendants.

Chlorine Gas Release

Neil M. Ram, Ph.D., LSP, CHMM

Southeast U.S.

Roux Associates evaluated the mass of aqueous-phase molecular chlorine (Cl2-aq) that the government alleged was absorbed into a river as a result of an airborne release of gaseous-phase molecular chlorine (Cl2-gas) from a train derailment. Roux Associates concluded that even small amounts of chlorine dissolving into the river would result in unstable chlorine species because the highly oxygenated waters resulted in free aqueous chlorine species being thermodynamically unstable (to the extent that any chlorine actually reached these waters). Therefore any chlorine impacts would not extend downriver. Further, at the pH values observed in the river following the incident, hypochlorous acid (HOCl) rather than molecular chlorine (Cl2-aq), would have been the predominant aqueous chlorine species to the extent that any chlorine reached these waters. Roux Associates also refuted (1) the Free Available Chlorine results reported for the river, because of transcription errors and undocumented lab methods and (2) a “Box Model” conducted by a government laboratory, because the model oversimplified the complex reactions governing the transport of the chlorine gas from gas phase to liquid phase and ignored the complex chlorine chemistry and associated aqueous-phase reactions. Roux Associate’s analysis demonstrated that the river had not been significantly impacted with chlorine. The case settled before trial.

Clean Water Act Case at Industrial Site

David G. Dixon, P.G.


Roux Associates was retained by defendant for litigation support for a suit filed under the Clean Water Act for storm water releases at their industrial facility. Roux reviewed the complaint and evaluated the technical basis of each claim, prepared responses for counsel, and reviewed and prepared technical letters. Tasks included evaluating the past site and regional storm water and soil sampling data, researching meteorological data, evaluating and improving facility Best Management Practices (BMPs) and conducting a background metals investigation in soil and storm water.

Roux received regulatory agency concurrence that metal exceedances of EPA Benchmarks were due to naturally occurring conditions and not facility operations. Roux consulted with legal counsel on potential settlement costs and prepared expert declarations in support of summary judgment. The case was dismissed by plaintiff prior to the Judge ruling on defendants request for summary judgment.

Defense of Soil and Groundwater Contamination Damage Claims

Jon Rohrer, P.G., C.Hg.


Roux Associates helped defend a Fortune 500 company against claims brought by a water agency plaintiff for environmental damages attributed to our client’s past operations, including groundwater remedial costs claimed by the agency. The primary issues in the case centered on past chemical use, release timing, and impacts to groundwater relative to a large regional plume.

Key aspects of Roux’s work included (1) identifying a previously unknown (to the plaintiff) outdoor TCE degreaser located immediately to the east of the defendant’s site and (2) illustrating the degree of impacts from a major source of contamination immediately to the north of the defendant’s site who was not named by the plaintiff as a target in the litigation.

Mr. Rohrer testified at trial, and the judge ruled in favor of our client.

Evaluation for a Former Chemical Waste Disposal Site

Nathan Epler, Ph.D.

New York

Plaintiffs alleged that their home and private water supply well were contaminated as a result of historical operations at a nearby chemical waste landfill, including the open burning of industrial wastes. This allegation was based on the detection of combustion by-products in attic dust within the home and contamination detected in their private well. Following a detailed review of case documents, Roux Associates prepared an affidavit in which we conclusively demonstrated the following:

  • The plaintiff’s expert was not qualified in the matters on which he opined;
  • The observation of combustion products in attic dust in the home was due to historical use of a wood-burning fireplace in the home and long-term use of cigarettes, not the burning of industrial wastes at the landfill; and
  • The private supply well was improperly constructed and was, as a result, contaminated by road runoff and fecal matter from an adjacent duck pond, not from impacted groundwater from the landfill.

The case was settled favorably for our client based on the affidavit.

Evaluation of Large Petroleum Release

Nathan Epler, Ph.D.


Roux Associates was asked to review a claim for reimbursement of damages due to an alleged large release of petroleum from an underground pipeline at a large petroleum terminal in Nevada. The claimant was seeking a multi-million dollar settlement against our client to pay for cleanup costs associated with the release. The evidence for the release was based on the sudden appearance of several feet of separate-phase product in a series of site monitoring wells during regular quarterly monitoring. During a review of years of site monitoring data, Roux Associates determined that due to a slow regional rise in water levels, most of the wells in the quarterly monitoring network had wells screens that no longer spanned the water table. This meant that the wells were not appropriately screened to be used for separate-phase product monitoring. A sudden decrease in water levels caused by shut-down of the Site air-sparge system for maintenance resulted in a rapid decline in water levels, which allowed existing product from old spills to enter the well screens, which made it look like a new release had occurred. Therefore, we concluded that the sudden discovery of product in Site monitoring wells was not due to a new release, but was in fact product from existing documented releases that simply migrated due to fluctuating water levels caused by shut-down of the air-sparge system. After deposition, the case settled favorably for our client.

Identifying Source and Age of HVOC Plumes

Adam H. Love, Ph.D.


Client was named PRP at a large multi-party site with claims of groundwater contamination concerns. The location included numerous site operators and adjacent property operators who were also known users of chlorinated solvents, so the amount of chemical contamination each PRP was contributing to the overall groundwater impact was unclear. Client needed a testifying expert to determine if the client had contributed to groundwater contamination concerns and, if so, how much the client contributed to the overall amount of contamination. Dr. Love developed fate and transport models of PCE, TCA, TCA, and 1,4 Dioxane plumes from the clients operations as well as other on-site and adjacent operations. The fate and transport models enabled better resolution of areas with distinct PRP plumes of contamination and areas of comingled plumes of contamination. Chemical fingerprint and degradation analyses of the chlorinated solvents enabled further apportionment of PRP contribution, even in areas of comingled plumes of contamination.

Court dismissed case based on lack of evidence of threat to groundwater.

Landfill Groundwater Contamination

Doug Swanson


Roux Associates was retained by the defendant and current owner of a parcel of land formerly used as landfill to evaluate the current and potential future impacts of groundwater contamination migrating from the former landfill on nearby residential wells. Nearby residential landowners had filed a class action lawsuit seeking damages for exposure to toxic substances allegedly emanating from the former landfill site. Roux Associates evaluated potential exposure pathways, including groundwater, and provided expert opinions as to the quality of groundwater downgradient of the former landfill, and the current and potential future extent of any impacts to residential and municipal well water. Roux opined that none of the residential wells downgradient from the former landfill was currently impacted, and the more distant regional municipal wells were too far away to be impacted now or in the future.

The class was ultimately not certified, and the case was settled and dismissed.

Public Water Supplier versus Private Commercial Client

Nathan Epler, Ph.D.

New York

Roux Associates provided a testifying hydrogeologic expert for a case involving impacts to a public supply well on Long Island alleged to have been caused in part by our client. Our client was named as a defendant by virtue of their being located in an industrial park that was the alleged source of the groundwater contamination in the supply well (tetrachloroethene and trichloroethene). An evaluation of historical soil and groundwater quality related to our client’s property, together with a review of historical regional groundwater flow directions in the area, indicated that our client could not have been the source of impacts to the supply well. Roux Associates was further able to demonstrate that there were other businesses in the area closer to the supply well that were the likely sources of impacts to the supply well.

The case was settled favorably for our client prior to trial.

Re-Evaluation of Groundwater Flow Direction

Nathan Epler, Ph.D.

New York

Our client was a defendant in a third-party lawsuit involving groundwater contamination of a downgradient public supply well. The Plaintiff alleged that our client also contributed to the supply-well contamination, and contamination on the plaintiff’s property, because our client was allegedly upgradient (across the street) based on years of regional groundwater level monitoring. Knowing that local groundwater flow directions can differ from regional flow directions, Roux Associates re-evaluated over 20 years of groundwater flow data. We determined that, locally, groundwater flow data did not indicate that our client was upgradient of the plaintiff’s property. In fact, groundwater flow data supported the opposite conclusion; that the plaintiff’s property was upgradient of our client’s. After deposition, the case was settled favorably for our client.

Source of Herbicide Causing Property Damage

Adam H. Love, Ph.D.


Client was the plaintiff in a lawsuit against the adjacent property owner suing for damages related to herbicide impact on mature trees along property boundary. The client was just a few months from trial and realized they were going to need a fate and transport expert to determine and testify to the possible locations from where herbicide could have been dispersed to cause the damage observed. Dr. Love was retained as the testifying expert. He performed a series of measurements of site conditions and impacts and tested the how far (vertically and horizontally) relevant dispersal technologies could direct a potential spray of herbicide. This information was integrated with atmospheric transport analysis and fate and transport analysis of herbicide after impacting the tree canopies and ground. His analyses enabled him to provide trial testimony that eliminated all locations, other than the defendant’s property, as the source locations for the herbicide impacts. Dr. Love was also able to describe to the court a reasonable scenario where the herbicide impacts observed could all be the result of actions on the defendant’s property using equipment/supplies available at residential hardware stores.

Court found defendant was liable for the damages. Plaintiff awarded triple damages.