Development and Analysis of Remedial Alternatives for Arsenic Impacted Ground Water

Remedial alternatives for arsenic impacted ground water at a former insecticide manufacturing facility are developed and analyzed in this thesis. Five remedial technologies are evaluated, including conventional pump and treat, monitored natural attenuation, soil flushing, electrokinetics, and in-situ fixation. Twelve case studies of arsenic impacted sites are developed from telephone interviews with USEPA remedial project managers. Each of the five remedial alternatives studied in this thesis has been implemented at one or more of the case study sites. At the present time, only one of the sites has requested site closure suggesting that currently available technologies are not efficient at attaining remedial goals. A comparative ground-water flow and solute transport model is constructed to simulate two base case remedial scenarios, pump and treat and monitored natural attenuation. Computer memory limitations only allow the model to simulate 275 years of solute transport. Therefore, regulatory standards were not achieved during model simulations. Geostatistical methods such as universal kriging and variogram analysis are used to analyze and develop a geostatistically accurate representation of site-specific data. Evaluation of a site-specific laboratory adsorption study indicates that sorption is overestimated by the calculated partitioning coefficient. Using the comparative model, site-specific retardation is re-estimated to lie between 20 and 30. The total mass of aqueous arsenic present at the site is estimated to be approximately 70 pounds and the total sorbed mass is estimated to be bound between 1400 pounds and 2170 pounds. The feasibility of all remedial scenarios is evaluated using criteria specified by the USEPA. A site-specific comparative analysis of alternatives indicates that monitored natural attenuation is the most appropriate remedial approach to manage arsenic impacts at the site. Potential risk associated with arsenic impacts at the site is relatively low because there is a lack of receptors for impacted ground water. Other remedial technologies are met with significant implementation problems such as property access restrictions, incompatibility with future remedial plans at the site, and high costs. Unsuccessful performance records for other technologies as described by the case studies lead to pessimistic outlooks for successful remediation at the site using the same technologies. Thesis Supervisor: Charles F. Harvey Title: Assistant Professor of Civil and Environmental Engineering