A reinforced earthfill was constructed using approximately 10 000 scrap tires. Water samples were collected from a drainage system installed below the tire-reinforced earthfill and analyzed for chemical quality. Additional tests on water quality were performed in laboratory test columns in which tire chips were embedded in sand or clay to provide a conservative estimate of the potential release of toxic compounds. Field monitoring of the effluent indicated that no significant adverse effects on groundwater quality had occurred over a period of 2 years. Laboratory batch tests performed on tire chips embedded in sand provided evidence of an increase in solution of certain metal elements which in some cases exceeds their respective drinking-water standards. This increase was attributed to the exposed steel reinforcement found in the tire chips. The amount of organic compounds leached from the tire chips decreased with the number of exposure periods or pore volumes flushed through the soil.Key words: whole scrap tires, water quality, tire chips, field investigation, laboratory lysimeter tests.