Abstract
Reusing drinking water sludge discharged during water purification is anticipated as a good use of waste materials as a geotechnical material. Mixing is certainly effective to improve the amount of supply materials. However, the effects of mixing on environmental economics have not been discussed. Therefore, such mixture must be examined from environmental and economical perspectives. This study defined the environmental value of drinking water sludge, with emphasis on the final disposal amount and the loss of natural soil. The environmental cost was estimated in various mixture conditions. Results show the benefits for geotechnical works of using drinking water sludge alone or decreasing the amount of mixed natural soils.