Project: Quartzsite Highway Project Quartzsite, AZ Engineering Firm: ADOT (Arizona Dept. of Transporation) Contractors: Kiewit Westeren, Flagstaff, AZ Application: Lightweight fill material over box culvert A road crossing a box culvert was being widened and elevated. The additional weight caused by the elevation would cause structural damage to the culvert. Geofoam was used to replace heavier fill materials to prevent weight induced damage.