Technical Integrity / Collaboration / Exceptional Results

Groundwater RI/FS and Remedial Design Support at a Former Smelter

Historical releases from a former smelter process pond created a mile-long plume of cadmium and zinc in groundwater beneath a populated area in Blackwell, Oklahoma. Since 2002, Integral has performed site investigations, fate and transport modeling, remedial technology evaluations, and remedial design to address historical releases from a smelter process pond and supported design and construction of a groundwater treatment facility. Central issues addressed by the remedial action were downstream risks to residents of the city of Blackwell from direct contact with and ingestion of groundwater from private wells, downstream recreational user contact and ingestion, and aquatic life impacts. Identification and characterization of the interactions between the municipal sanitary and storm sewer systems and the water table within the area of impacted groundwater supported the design of a groundwater extraction system and aided in planning the refurbishment of a portion of the storm sewer system.

Integral performed a thorough evaluation of remedial alternatives, executed field and laboratory pilot tests of remediation technologies (permeable reactive barriers and in situ groundwater treatment), and prepared an engineering feasibility study that resulted in the selection of the groundwater remedy. The selected remedy extracts groundwater to capture and treat the plume, and to lower the water table below sections of the sewer system vulnerable to infiltration of contaminated groundwater. The extracted groundwater is treated by a sodium hydrosulfide treatment system, which achieves the low cadmium and zinc concentrations in treated effluent necessary to meet permit standards and produces a solid-waste stream from which zinc can be economically recycled.

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