Remedial Construction Using AquaBlok-Based Technology to Place ISCR Reagents for Arsenic and Selenium Immobilization

摘要

Objectives. AquaGate~(TM) is an AquaBlok-based technology that supports the uniform and targeted placement of high-value/low concentration treatment amendments. The geotechnical aspects of the materials include a range of permeabilities (AquaBlok is a low permeability [<10E-8 cm/sec] ‘sealant’ for “funnel” material, and AquaGate is a higher permeability [>10E-4 cm/sec] ‘filtration’ material for treatment “gates”). Each of these products can provide other unique geotechnical properties, such as designed shear strength and bearing capacity. These materials can also be formulated with various remedial amendments to meet site-specific needs. One such amendment, EHC?, combines controlled-release particulate carbon material and micro-scale zero valent iron (ZVI) or other metals to uniquely yield in situ chemical reduction (ISCR). EHC-M is similar but it also contains an internal source of slowly dissolving sulfate salts to promote formation of sulfide minerals in sulfate-depleted environments. Treatment of metals such as arsenic in an EHC-M ISCR zone involves the reduction of adsorbed arsenate [As(V)] anions to arsenite [As(III)] coupled with their long-term sequestration as solid arsenic species by means of reductive precipitation and adsorption onto the iron corrosion products.