In Spring 1990 the Utah Department of Transportation (UDOT) was responsible for disposing of 3, 200 cu yd of alkali solid waste and 891, 000 gal of wastewater resulting from a large scale pavement grinding project (12 lane-mi on I-15). Numerous disposal methods were considered and reviewed for both cost and potential for success. Detailed laboratory testing was conducted as part of the preliminary investigation. UDOT worked closely with the Utah Division of Environmental Health in arriving at a solution. Ultimately, a decision was reached to recycle the solid waste into a road project, where it would serve as the mineral filler in a portland cement-treated base course. Disposal project phases included initial grinding, characterization of the waste material, heuristic evaluation of possible stabilization methodologies, wastewater treatment and solids interim storage, and final project design and placement. Care was taken to ensure that the material and wastewater were handled in an environmentally safe manner. Water was decanted from the grinding slurry, filtered to remove the suspended solids, and treated with sulfuric acid to lower the pH before disposal. A major emphasis in the pavement structural section design was to eliminate the possibility of future ground-watercontamination on-site
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