The overall objective of this project is to evaluate the impact of key constituents captured from power plant air streams (arsenic, selenium and mercury) on the disposal and utilization of coal combustion by-products.  Specific objectives of the project are: 1) to develop a comprehensive database of field leachate concentrations at a wide range of CCB management sites (about 25 sites), including speciation of arsenic and selenium, and low-detection limit analyses for mercury; and 2) to perform detailed evaluations of the release and attenuation of arsenic and selenium species at 3 CCB sites.

The fundamental or mechanistic data to reliably model many of the inorganics in CCB leachate are lacking.  There is a large degree of uncertainty in the initial leachate concentrations, long-term leaching characteristics of CCBs, and the attenuation coefficients typically used in groundwater transport models.  As a result, the model simulations are either highly conservative, or they can be manipulated to obtain almost any desired result. This research project will develop a coherent field leachate database and soil attenuation coefficients for improved modeling and evaluation of the potential for groundwater impacts at CCB management facilities.  The work is focused on speciation of four key constituents at CCB sites: arsenic, selenium, chromium, and mercury.  The proposed work will help to narrow the uncertainties in the range of values of these critical inputs and improve the accuracy of the modeling results.