In conjunction with the ongoing construction on 176th Street East, Pierce County Public Works and Utilities took an innovative approach to treating stormwater runoff generated by the new roadway improvements. Instead of constructing a traditional detention pond, the Office of the County Engineer designed a reinforced concrete stormwater detention system just west of 86th Avenue East.

This underground system is made up of three compartments, each designed to maximize space so that the system can provide the proper amount of storage volume to meet current requirements.

A control structure, located at the lower end of the vault, releases water slow enough to prevent any increased stream flows and to ensure the environment is not adversely affected.

The Office of the County Engineer chose to design this system for two important reasons. There was no land available for a traditional detention pond, and this system was more cost-effective than building aluminum holding tanks.

“When we construct high-impact road projects, we have environmental and regulatory responsibilities, but we also have to be the best stewards of the available funding,” Engineering Manager Ramiro Chavez said. “In choosing to install this kind of stormwater detention system, we looked at all available options, and decided to take an innovative approach. I am proud of our engineers for finding the right solution to this particular challenge.”

For more information on the 176th Street East improvements, visit http://www.piercecountywa.org/fredericksonarea .