"Evaluation of Cumulative Risk from
an Iron Foundry"
Steven J. Klafka, P.E., DEE
ABSTRACT
Hazardous air pollutant (HAP)
regulations in Wisconsin required a cumulative impact analysis for an
existing iron foundry. The combined inhalation risk was not allowed to
exceed 10 x 10-6. A comprehensive emissions inventory was
compiled for 16 individual HAP released from 82 foundry operations,
emergency generators and natural gas combustion. Evaluated HAP included
benzene, formaldehyde, polychlorinated dibenzo-p-dioxin,
polychlorinated dibenzofurans, trace metals and polyaromatic
hydrocarbons. To simplify the analysis, emissions from each discharge
point were reduced to an equivalent quantity of benzene emissions,
referred to as “TEQ as Benzene”. The equivalent emissions were
calculated using a ratio of the unit risk value for each HAP and that
of benzene. Downwind air pollutant concentrations were predicted using
the ISC3 dispersion model. The cumulative risk was then estimated by
applying the unit risk value of benzene to the predicted
concentrations. The analysis verified that the estimated cumulative
risk due to foundry operations was less than the 10 x 10-6
requirement.
