In January 2020, Sacramento Regional County Sanitation District (Sac Regional) awarded W. M. Lyles Co. the N19 Arden Pump Station Wetwell Rehabilitation. The project site was a decommissioned wastewater treatment plant with the headworks structure converted into one of the largest pump stations in Sacramento. Gravity flow into the former headworks could not be shut down or rerouted to accommodate improvements; consequently a 27 MGD dry season bypass pumping plan was required. Safe entry into the 50’ deep wetwell also required backup bypass pumps, overflow alarms, diesel fueling system and around the clock bypass monitoring. Work inside the wetwell began with a massive dewater and cleaning effort, followed by pump inlet pipe repair, concrete rehabilitation, and recoating of the lower and upper wetwells. Additional scope included selective demolition, 78’’ and 54’’ slide gate replacement, new stop log frame installation, lighting, level controls, miscellaneous metals, bridge crane and electrical upgrades. The lower wetwell had not been accessed since the headworks conversion over 40 years ago and the interior condition was unknown. The pump station rehabilitation finished ahead of the fall rains as required.