Station 20 is a 345‑kV switchyard serving the Braidwood Nuclear Power Station in Braidwood, Illinois. Originally designed and constructed in the mid‑1980s, the switchyard’s original drainage system consisted of three main lines of perforated corrugated metal pipe discharging into a common underground oil‑water separator. Over time, corrosion caused portions of the drainage system to collapse, resulting in sinkholes forming near critical electrical equipment.
Primera was contracted to provide civil and structural engineering services to design a reinforced concrete pipe replacement drainage system that would restore system reliability while maintaining uninterrupted operation of the switchyard.
The replacement drainage system was designed to be constructed in three distinct phases, allowing the switchyard to remain in service throughout construction. The project required development of demolition plans, modifications to existing site grading, detailed plan and profile drawings, and the design of 45 new drainage structures and approximately 2,600 feet of storm sewer piping. In addition to civil design services, Primera provided project management, coordinated the topographic survey and geotechnical investigation, and performed structural reviews of proposed excavations adjacent to existing foundations and equipment.
The drainage system was designed using AutoCAD Civil 3D in conjunction with Hydraflow storm sewer modeling software. These tools allowed Primera to rapidly evaluate design modifications necessitated by unforeseen field conditions encountered during construction and to issue revised construction documents efficiently. This ability to respond quickly to changing site conditions enabled the project to proceed without disruption while minimizing risk to critical switchyard infrastructure.
