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Willdan Engineering has expertise in all aspects of drainage and flood control, ranging from local and regional drainage and flood control improvements to hydraulic and sediment transport analyses of major rivers. Willdan Engineering has worked with numerous cities to ensure compliance with the National Pollutant Discharge Elimination System (NPDES) municipal storm drain requirements.
- Master Plans
- GIS services
- Hydrology Reports
- Feasibility Studies
- Federal Insurance Studies (LOMR, CLOMR)
- Storm Water and Drainage Design
- Channel Improvements
- Pollution Discharge Requirements/Permit Processing
- Hydraulic Models
- Scour and Sediment Transport Analysis
- Debris Dam and Side Weir Design
- Retention and Detention Basin
Representative Projects
U.S. Army Corps of Engineers, L.A. River — Los Angeles County, California
APWA National Project of the Year, Disaster or Emergency Construction/Repair
This award-winning, five-year project increases the floodwater capacities of both the Rio Hondo Channel and the Los Angeles River to facilitate a 133-year storm, saving residents in 14 communities millions of dollars in flood insurance. The $216-million project raised the height of 21 miles of existing levees from 3 to 6 feet and modified 24 bridges.
Willdan was responsible for more than $130 million in preliminary and final design of channel improvements; railroad, pedestrian and utility bridges; parapet walls; access roads; and landscaping.
The Los Angeles County Drainage Area Project received the American Public Works Association 2002 "Project of the Year" in the category of Disaster or Emergency Construction/Repair More than $10 Million. The APWA Reporter noted:
"Innovative engineering, effective project management, sustained coordination between agencies, and considerable public outreach enabled the completion of the project five years ahead of schedule and 40 % under budget (saving $150 million).... It involved careful planning to include environmental and community concerns and values in the design and construction procedures employed."
U.S. Army Corps of Engineers, Santa Ana River — Orange County, California
ASCE Orange County, Project of the Year
The Santa Ana River Reach 2 Project doubled channel capacity. The jurisdictional agencies involved were the Corps of Engineers, the County of Orange, the Cities of Costa Mesa and Huntington Beach, the Edison Company, Orange County Sanitation District, and Caltrans. The often conflicting requirements of the agencies, as well as numerous homeowner groups and the Orange County Bicycle Association, were negotiated and incorporated into the design. Reaches 3 and 4 had ten bridge undercrossings that were designed to California DOT bicycle trail design criteria.
The project was bid on schedule at a significant savings to the Corps, and construction was done on schedule despite the fifth heaviest rainy season in Southern California history. The Santa Ana River Improvements project won the Project of the Year Award from the ASCE Orange County branch in 1996.
City of Rancho Cucamonga, Day Creek Detention Basin — San Bernardino County, California
Day Creek is a $40 million system composed of a debris dam, an interceptor berm, groundwater recharge basins, three detention basins, and ten miles of rectangular reinforced concrete channel. The upstream end of the system is the Day Creek Debris Basin, with a high velocity spillway, an underdrain with a inlet tower and U.S. Bureau of Reclamation dissipation structure, and 650,000 cubic yards of debris storage. Because of its size, the debris basin was processed through the State Department of Safety of Dams and the spillway was sized for the Federal PMF Storm Event.
