World’s Largest Tunnel Carwash

This project is the world’s longest tunnel carwash. The original design had to be squeezed to fit with the addition of a right-turn lane that was required by UDOT. Due to this reduction in length and the grades required for the carwash, retaining walls were required on both ends of the carwash. This created a challenge with capturing all the site storm water with the same highwater mark for all ponds. The original site had silty clay soil with some areas of non-engineered silty clay fills. Due to this the minimal infiltration protentional, the detention has limited ability to recharge the ground water requiring a system that could contain all of the required storm water. Both above ground and below ground stormwater detention were used to contain the water with a tiered release system.