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Air Toxics Health Risk AssessmentCompliance
with air quality regulations increasingly requires performing risk assessments
to estimate potential human health consequences from exposure to air pollutants.
EES staff has assisted clients with air toxics risk assessments in the
context of New Source Review permitting, state and local air toxics regulations,
like the California Air Toxics “Hot Spots” and Information Act (AB2588) and
Safe Drinking Water and Toxics Enforcement Act (Proposition 65) and Superfund
and RCRA projects. In addition,
Title III of the 1990 Clean Air Act Amendments introduced a new requirement to
evaluate the “residual risk” associated with hazardous air pollutant
emissions after implementation of maximum achievable control technology (MACT).
Typically,
the air toxics health risk assessment for a given activity considers exposure of
neighboring populations to potentially hazardous compounds by way of multiple
environmental pathways (e.g., inhalation, dermal absorption, ingestion).
These analyses are designed to determine the pathways responsible for the
largest exposures at sensitive receptor locations and, if necessary, to identify
viable mitigation measures to reduce health risks to acceptable levels. Representative
examples of EES’s experience in this technical area are provided below. Air Toxics Health Risk
Assessments ARCO
Products Company EES staff
helped to prepare air toxics health risk assessments for six ARCO facilities as
required by the California Air Toxics “Hot Spots” Information and Assessment
Act of 1987. These facilities
included an offshore oil and gas platform (Holly) and associated support boats,
three onshore production leases (Dos Pueblos, Ellwood Beach, Ojai), an oil and
gas processing plant (Ellwood), and a bulk gasoline terminal (San Diego).
For each of these assessments, EES staff prepared site‑specific
emissions and meteorological data sets, performed dispersion modeling, and
applied a risk quantification model to estimate total community health risks
associated with toxic emissions from the subject facilities.
Detailed reports documenting the input data, assumptions, analytical
methods, and results were prepared for each health risk assessment. EIR
and Health Risk Assessment Hazardous
Waste Disposal Facility EES engineers
helped the County of Imperial to prepare a comprehensive environmental impact
report (EIR) for a proposed expansion of an existing waste disposal facility
near Westmorland, California. The
existing facility consists of landfills for geothermal and other nonhazardous
wastes; the proposed project would entail the addition of new facilities for the
treatment and disposal of both hazardous and nonhazardous wastes.
Originally, a health risk assessment was conducted by another consulting
firm under contract to the county and incorporated into the EIR prepared by EES.
Because of serious problems with the air toxics element of the health
risk assessment that were identified by the reviewing agencies (CARB, DOHS, and
Imperial County Department of Health Services), EES staff was requested to
re‑do the ATHRA following the CAPCOA guidelines for AB 2588.
The EES staff analysis was accepted without further revisions by the
reviewing agencies and the EIR was subsequently certified. A variety of air toxics sources were addressed for the expanded waste disposal facility: (1) fugitive dust generated by the handling of dry materials in the waste stabilization process units and landfill operations; (2) fugitive organic vapors collected from liquid waste storage and processing facilities; (3) combustion or organic vapors in a new steam generator; and (4) potential accidental releases from transportation and process upset conditions. Owing to the diversity of the types of wastes that will be received at the facility, a wide range of specific organic and inorganic toxic contaminants were addressed. Air
Toxics Health Risk Assessment for a Major West Coast Shipyard National
Steel and Shipbuilding Company EES engineers
provided comprehensive air toxics consulting services pursuant to California
AB2588, including preparation of an air
toxics emissions inventory plan, air toxics emissions inventory report and air
toxics health risk assessment for this major San Diego shipbuilding and ship
repair facility. Project activities
included extensive researching of the technical literature to determine the most
realistic available emissions factors for relevant facility processes, in
particular factors for lead, hexavalent chromium and nickel from welding
operations and oil combustion. The
exposure of nearby residents to these emissions was evaluated by means of
dispersion modeling, as were potential health risks, using approved risk
assessment software. EES staff also
assisted in developing analyses for review by the California Attorney General
pursuant to Proposition 65 requirements
for the facility. Health Risk Assessment Vulcan
Materials, Calmat Division EES staff
managed the preparation of a Health Risk Assessment (HRA) conducted for an
aggregate handling facility addressing the requirements of the State of
California, Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition
65). Responsibilities involved
close coordination with the client’s legal team to establish best technical
and legal strategy, emissions quantification, risk analysis, and environmental
impact from the aggregate operations. Air
Toxics Health Risk Assessments National
Refractories and Minerals Corporation EES staff has provided full service air toxics
consulting support for AB 2588 compliance at NRM’s two facilities in
Monterey County. These are:
a dolomite quarry with crushing and calcining operations at Natividad;
and magnesia and refractory brick production at Moss Landing.
EES staff has prepared air toxics emissions inventory plans and air
toxics emissions inventory reports for both facilities and obtained approvals
for these documents from the Monterey Bay Unified Air Pollution Control District
(MBUAPCD). Extensive source testing
to quantify air toxics emissions from NRM sources was required by MBUAPCD.
EES staff assisted NRM in devising a test program that made use of pooled
data, so that only a fraction of the many individual sources were tested. Additionally, EES staff prepared the required air
toxics health risk assessments (ATHRAs) for the Natividad and Moss Landing
facilities. Protocols consistent
with MBUAPCD guidelines for AB 2588 ATHRAs were presented to the district
and subsequently approved. A key
component of this effort was the identification and location of sensitive
receptors (i.e., hospitals, schools, child and adult day‑care centers,
elderly residential areas, and group homes) within a 50km radius of the
facility. Subsequently, the cancer
and non-cancer health risk was determined for AB 2588 substances
emitted by each facility. The
concentration and corresponding health risk of emitted substances at 820 receptors
located adjacent to the Moss Landing facility property boundary was of
particular importance. This
condition was based on the fact (1) that sensitive receptors existed and
(2) that an adjacent industrial firm was known to emit identical
substances. As a result of this
health risk assessment, it was determined that sensitive receptors were not
exposed to toxic chemicals in concentrations that warranted risk reduction or
pollutant source emission control actions. |
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