In the Spring of 2019, the City of Sacramento utilized a best value selection process to award W. M. Lyles Co. the McKinley Water Vault construction project. As one of only two large California cities that still operate with a combined storm water and wastewater system, Sacramento has been particularly vulnerable to major storm events that can overwhelm the existing sewer/storm capacity and overflow mixed wastewater onto low-lying streets and neighborhoods. This high profile project was a key component to the City’s long-term strategy to eliminate wastewater flooding in East Sacramento and incorporated a new football field sized storage tank beneath the historically significant McKinley Park. During a heavy rain event, the large underground cistern and new sewer connections are designed to capture rising water before it reaches the street level. Once the rain subsides, the stored contaminated flood water safely returns to the combined sewer system undetected by the park occupants.

The initial scope of work included detailed demolition inside the park, follow by more than 10,500 SF of soil nail shoring and the haul off of 64,000 CY of excavated material. This work was followed by the construction of a 6 million gallon underground cast-in-place concrete wastewater storage reservoir with 70,000 SF of shored deck, an effluent return pump station, odor control structure, valve vault, diversion structure and associated pipelines. The remaining scope of work included the backfill and compaction of 20,000 CY of imported fill, a combined prefabricated public restroom that houses the electrical gear and water pressure boosting equipment, new park amenities and significant landscape upgrades within the construction site.