The Use of High Resolution Characterization to Develop and Implement Site Remediation

English Abstract:

Remediation of impacted sites can be challenging due to numerous factors including geologic heterogeneity which can result in complicated distribution of the compounds of concern. Remedial efforts to remediate these compounds of concern are often frustrated due to a lack of understanding of the geology, hydrogeology and geochemistry. Site specific factors such as geology, hydrogeology, geochemistry, contaminant distribution, etc. play important roles in controlling the design of any successful remedial program especially in situ based programs. Very few studies have been completed in the field to look at why in situ remedial programs have had mixed success.

A comprehensive field study was carried out at a site in Southern Ontario to evaluate the effect of various injection and delivery methods for three common oxidants; persulphate, percarbonate and hydrogen peroxide. The effect of the oxidant type and delivery method on the distribution and persistence of the oxidant within the subsurface was also examined. Delivery methods examined for each oxidant included direct push using drop points and side tools along with vertical wells. The results of the study indicated that the method of injection had a significant impact on the distribution at the site tested. The persistence of the oxidants were also evaluated and a large variability in persistence was noted between the three oxidants with percarbonate existing the longest within the subsurface followed by activated persulphate and hydrogen peroxide. These results suggest that the choice of oxidant and delivery method are key design parameters for any in situ remedial program.