Residents Sue Sewer Engineer Over Hazardous Waste


Engineering Expert WitnessThis environmental health case involves a landfill that has been exposed to numerous toxic chemicals in Utah. The landfill in question was a hazardous waste disposal site, and contained hundreds of distinct chemicals. Eventually, an apartment complex was built on and around the site, which was found to be exposing residents to toxic substances. Remediation efforts went underway sometime later, and included constructing containment and drainage systems to prevent further migration of toxic chemicals. Eventually, the defendants disturbed and exposed contaminated sediment and waste while performing sewer remediation work, and the released toxins spread from the sewers to the plaintiff’s apartments. The plaintiffs of this case began to develop various illnesses, and claimed the onset of cancer and an impacted reproductive capacity to be a direct result of the environmental toxins.

Question(s) For Expert Witness

  • 1. How do these substances move from containment site, or actual dumping ground, through the town, and how do sewers move and migrate hazardous materials?

Expert Witness Response E-127572

I am a professor of civil and environmental engineering with over 30 years of experience, and my specialty is the sub-surface transportation of contaminants. Sewers are generally not sealed completely and it would be understandable if they were conduits for gas or liquids. I would be interested in examining the networks, flow direction, and gradients. There are also other candidates for transportation: cracks in the roads, drainage, and other technical engineering features must be examined. To prevent toxins from escaping a contaminated site, barriers can be put into place, but they only slow contaminant transport. They never stop it completely. Barrier disruption opens up fast transport pathways and exposure routes. Removal and incineration may be the only safe way to eliminate risks in a situation like this case.

Expert Witness Response E-030616

I have extensive experience with soil and groundwater remediation and with contaminant fate and transport in the environment, particularly with organic contaminants. In general, contaminants discharged at land surface migrate vertically downwards under the influence of gravity until reaching the water table, at which point the flow of the groundwater becomes a mechanism for contaminant transport. One important factor here may be a rising water table prior to the renovation efforts, which could have facilitated the spread of contaminants to the residents’ homes. From the case overview, it sounds like sediment-facilitated transport might also be important in this case; contaminants absorb, or ‘stick’ to grains of sand, silt, or clay, and then if those particles of sand, silt, or clay are washed from one location to another, with the contaminants going along for the ride. This process could possibly be an important transport mechanism in the sewers.

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