Example Projects


For more than three decades, Gradient has conducted technical analyses to help our clients address human and ecological risk assessment issues on a wide variety of infrastructure projects.

Infrastructure projects, in the areas of transportation (e.g., harbors/marinas, roads, rail, aviation), telecommunications, and energy production and distribution, can be highly complex projects, which may involve a variety of contaminant release, exposure, and risk scenarios. With the population increasing and the growing need to repair, update, and expand fundamental facilities and systems within the United States, the number of largescale infrastructure projects is rising.

Gradient’s infrastructure project work has ranged from evaluating potential contaminant releases and developing risk-based remedial strategies to risk communication with scientific and non-scientific stakeholders (e.g., in community meetings, regulatory processes, and litigation settings). We have a proven track record of facilitating the following types of projects while ensuring the protection of public health and the environment: tunnels and bridges, waterways and ports, real estate, subways, railroads, roads, oil and gas, utilities, pipelines, and building materials.

Gradient Infrastructure Expertise:

  • CERCLA, RCRA, property transfers, voluntary actions
  • Risk-based cleanup levels
  • Assessment of non-standard exposure scenarios
  • Climate-related vulnerability assessments for infrastructure and communities
  • Environmental justice
  • Risk communication
  • Health impact assessments


Example Projects

Exposure Analysis and Human Health Risk Assessment Support for Subway Tunnel Reconstruction

Full Description

Gradient provided technical support in identifying risks to public transit riders from potential exposure to particulate matter (PM) and respirable crystalline silica (RCS) during subway tunnel construction. We reviewed PM and RCS data, standards, ambient levels, and exposure guidelines, and assessed potential exposure scenarios for subway riders. We recommended health-based benchmarks and developed risk communication materials to help the transit authority address potential public health concerns related to the tunnel construction.

Support for a Natural Gas Compressor Station Project

Full Description

Gradient provided technical support and expert testimony for the appeal of an air permit approval for natural gas compressor station construction and operation. We provided guidance on air exposure and health risk assessment, evaluated air monitoring and modeling data, and critically reviewed public health studies, exposure studies, and a health impact assessment (HIA) prepared by state agencies. A Gradient expert provided testimony on toxicology, air exposures, and the meaning of state guidelines at the appeal hearing.

Monitoring Program for Architectural Materials

Full Description

Gradient designed a lead sampling and monitoring plan in and around a condominium building to assess the extent to which the lead-coated copper (LCC) architectural roofing materials used for the building might contribute to lead exposure to the building residents and the general public. Our analysis also included materials testing to evaluate the effect of an encapsulation approach.

Risk Assessment for Paving Asphalt Fumes

Full Description

Gradient conducted a cancer risk assessment for polycyclic aromatic hydrocarbons (PAHs) present in paving asphalt fumes. We compiled information to support the calculation of the lifetime cancer risk associated with occupational exposure to hot asphalt from road paving systems. We also developed a framework to account for uncertainty and variability in asphalt composition, asphalt fume measurement techniques, job categories, and exposure scenarios.