Environmental

Challenge: To address potential offsite toxicological inhalation impacts from volatile aqueous substances in a densely populated urban area with complex atmospheric and terrain features. 

Solution: INTERA prepared evaporative emissions calculations for the subject substances at several locations at the subject site. These estimations were based on the storage volume of the containers and respective containment areas. Using these emissions estimates, refined air dispersion modeling was conducted to determine offsite impacts within the vicinity of the site, which was located in a highly developed and densely populated urban area. A contour graphic with an aerial overlay was developed to demonstrate the potential impacts relative to the release location. Due to the absence of inhalation toxicological data and peer reviewed studies, a toxicological bridging analysis was conducted to develop toxicity endpoints for the subject chemicals based on chemically similar substances where health effects standards and peer-reviewed data has been established. These toxicity endpoints were established to serve the same function as the No Observed Adverse Effect Level (NOAEL) exposure level. 

Results: INTERA’s analyses provided a better understanding of the potential offsite impacts of the client’s products on neighboring properties, allowing them to be better stewards of the surrounding environment.  

Challenge: To amend and renew a New Source Review (NSR) air permit for a batch chemical manufacturing facility 

Solution: SACHEM’s batch chemical manufacturing facility is located in the Dallas-Fort Worth (DFW) ozone nonattainment area.  The facility manufactures hundreds of batch chemicals, and consists of process equipment that includes reactors, rotary vacuum dryers, electrochemical process cells, and other relevant specialty process units. The site handles a multitude of organic and inorganic chemicals as raw materials, finished products, and co-/by-products, which were required to be speciated and evaluated for health effects per Texas Commission on Environmental Quality (TCEQ) rules. Over 100 individual chemicals required calculation, evaluation, and modeling to demonstrate off-property impacts. To amend and renew the air permit, INTERA collected information through a facility visit that included staff interviews and via a desktop review of air permits and associated compliance documents. Emissions were calculated for each stationary source using methodologies prescribed by the TCEQ, site-specific engineering calculations incorporating several thermodynamic models, EPA’s AP-42, and other industry-accepted practices as applicable. Once the emissions were calculated, they were screened using TCEQ’s Modeling and Effects Review Applicability analysis to determine which chemicals screened out as de minimis emitters and which required further modeling. Emissions modeling was conducted using the Industrial Source Complex (ISC) model for each affected emission point at a rate of 1 lb/hr to generate a Unit Impact Multiplier (UIM). Each hourly emission rate was multiplied by the UIM to determine a maximum offsite impact, which was then compared to TCEQ’s Effect Screening Levels (ESLs) and the National Ambient Air Quality Standards (NAAQS) to determine the impacts to off-property human health and vegetation. Ultimately, the modeling demonstrated that all emissions were not harmful to offsite receptors and were acceptable to TCEQ’s Toxicology Division. INTERA interacted with the site staff and the TCEQ regularly as it pertained to the progress of the review of the application, including answering clarifying questions for the agency, refining calculations and estimations as appropriate in conjunction with the appropriate stakeholders, and in negotiations of final permit content and conditions. 

Results: INTERA’s work resulted in a successfully amended and renewed NSR permit.