Nashville’s Central Wastewater Treatment Plant Capacity Improvements and CSO Reduction project is set to increase the facility’s peak plant capacity from 330 million gallons per day to over 400. As a core infrastructure improvement project, the city needed a partner capable of complex, industrial electrical solutions within a tight schedule. Feyen Zylstra stepped up and was awarded the complete electrical package including power distribution, medium voltage, instrumentation, communications, and fire alarm. Currently, our team has installed the underground in slab embedded conduit and duct banks. We’ve also roughed in the conduit for the instrumentation, communications, and fire alarm and completed all project wiring and preliminary start up activities.

As an infrastructural replacement, our team is building a new solid processing facility that will replace the existing, overloaded facility. Once the project is completed, the existing sewage lines will be cut over to the new ones, leaving no room for failure or downtime. For this reason, function and quality are of the utmost importance. Part of our work included completely remodeling a traffic intersection to incorporate the new plant’s entrance. This included new traffic signals, sidewalks, and ADA ramps all to Metro Nashville’s standards.

Due to open wastewater channels, the entire building requires Class 1 Division 1 Hazardous Location materials. These materials include stainless steel conduit that requires specialized oil, dyes, and compounds. Also required are explosion proof seal offs and fittings that are larger, heavier, and more difficult to work with as compared to their traditional counterparts.

Owing to the nature of wastewater management, the schedule is broken up into multiple, segmented concrete pours. Our team utilizes heavy preplanning to maintain a steady workforce throughout the duration of the project. Despite the inefficiencies that segmented concrete construction can pose, our team has been able to beat all of the in slab conduit schedule durations.

A unique challenge of the project is that the site is built on solid rock. When it came time to install the duct banks, our team had to jackhammer into the rock, in some cases over 8 feet deep. For the duct banks that were situated underneath the structure, the entire execution was poured into solid concrete. Since accuracy is critical when locating duct bank locations, our team relied on a BIM model, clash coordination, and the use of a Trimble to help accurately identify and mark the locations prior to installation.

Weather also posed a challenge throughout construction. With only the main electrical building providing coverage, the majority of our work is completed with full exposure to the elements - heat, cold, rain, etc. Owing to the solid rock foundation, whenever it would rain the entire project site would flood. We were able to help solve this challenge by hooking up temporary power to pumps that would clear water away from the job site.