Water Canyon/West Jemez Storm Drain Project - Los Alamos, NM

Wilson & Company helped Los Alamos National Laboratory (LANL) to analyze and design reconstruction of a drainage structure crossing NM 501, near NM4, for the Water Canyon watershed. After the 2011 Las Conchas Fire, the existing drainage structure (36” Corrugated Metal Pipe) became plugged with debris after storm runoff and no longer conveyed flows. This resulted in a safety hazard as the roadway acted as a dam and during larger storm events, water overtopped the roadway, making it impassable for motorists.

Wilson & Company first prepared a thorough drainage report that analyzed both the pre-burn and post-burn conditions. The preferred alternative was a precast 10’x10’ concrete box culvert based on budget, time constraints and the ability to convey the 50-year, 24-hour storm. Boxes were cast in Albuquerque and shipped to the site. Excavation and installation of the precast boxes was coordinated with NMDOT during a weekend road closure. Inlet wingwalls were then cast in the field and a grouted riprap plunge pool was installed on the outlet. Wilson & Company used HEC-HMS along with other hydrologic modeling software to ensure the design would accommodate large storm events and release runoff at an acceptable flow rate.