Various FEMA Projects
Schaaf & Wheeler has completed Flood Insurance Studies for numerous cities and counties throughout California for the Federal Emergency Management Agency (FEMA). The studies have included defining the flood hydrology for various creeks, streams and channels as well as floodplain hydraulics and floodway determination. The watercourses have varied from heavily urbanized, concrete-lined channels to broad streams and floodplains in rural counties.
Projects of note include work on the Los Angeles River and on eight major watercourses in San Joaquin County north and east of the city of Stockton. For the Los Angeles River, the lower 25 miles of the concrete lined channel were subjected to careful scrutiny to define channel capacity and to assess the effect that numerous bridge crossings could have on that Corps project's ability to carry the 100-year flood peak discharge safely. In San Joaquin County, the study areas included extensive leveed channels in urban and agricultural areas. The existing capacity and freeboard levels of several flood control project channels constructed by the Corps of Engineers and the US Department of Agriculture were of particular concern. Due to channel levees and flat terrain, floodplains were delineated over extensive areas. Shallow overbank flooding was mapped in both urban and agricultural areas. The study involved the application of FEMA levee criteria for an extensive levee system. Significant coordination with FEMA in Washington, DC was required to develop appropriate analysis procedures for the application of the FEMA levee policy in this complex system of flood control levees.
Schaaf & Wheeler engineers have delineated floodplain and defined floodways in areas shown on the map above. The map also shows areas where the Firm's engineers have succesfully completed CLOMR's and other floodplain related projects for a variety of public and private clients.
City Of Livermore
Schaaf & Wheeler performed a storm drain master plan for the city of Livermore. Under this project the City's storm drainage system was evaluated for 10 and 100 year storm events. The highly sophisticated MOUSE model was used for this study. MOUSE combines the use of GIS, SCS unit hydrograph urban hydrology methods and models flow in the underground pipe networks, as well as surcharged flow running along streets. The city's system is greatly affected by the water levels in flood control channels and streams; FEMA and Zone 7 HEC-RAS models were reviewed to determine the appropriate boundary conditions for the MOUSE models. Existing and future development conditions were modeled to determine potential storm drain improvements. Schaaf & Wheeler staff worked closely with the City to categorize the capital improvement projects by cost and urgency.
O'Neil Slough Tide Gate Restoration
Schaaf & Wheeler completed a comprehensive flood management strategies report for the City of San Mateo in 2002. To provide flood protection against tidal water from San Francisco Bay meeting national standards, a series of improvement projects to the coastal levee protection system were recommended. Schaaf & Wheeler was engaged by the City to prepare the analyses, engineering documents and environmental assessments necessary to complete the recommended improvements, which include:
* Raised and improved levees from the Burlingame City limit to Coyote Point.
*A series of berms, structural flood walls, grading, repaving, and landscaping within Coyote Point Recreational Area.
* Improvements to the Bay Front levee system.
* A new structural flood wall in the vicinity of the wastewater treatment plant.
* Rehabilitation of a tide gate structure and associated levee improvements and flood walls near the O'Neill Slough entrance to Marina Lagoon.
The initial phase of work concentrated on obtaining FEMA approval for the projects, and includes detailed geotechnical levee stability analyses by TRC (Lowney). In the second phase of work, Schaaf & Wheeler completed the contract documents, obtained necessary regulatory approval, and provided construction oversight.
Channel Layback And Restoration Project
Client: University of California, Santa Barbara
Location: Santa Barbara, CA
There were multiple objectives with this project, including; bank stabilization, increased flood capacity, and ecological restoration. The existing banks of Phelps Creek were actively eroding, and invasive species both limited valuable habitat and channel capacity. Schaaf & Wheeler worked with the University of Santa Barbara to design and construct a project to layback the eastern bank of the Creek to address these multiple objectives (the western bank is not University property). Schaaf & Wheeler led an effort to balance the project goals and create design consensus with the site developers, the California Coastal Commission, the California Department of Fish & Game, and the University’s Cheadle Center for Biodiversity and Ecological Restoration (CCBER). The final design completed by Schaaf & Wheeler created a multi-staged east bank with a combination of biological engineering methodologies and enhanced ecological habitat such as a wetland swale, floodplain bench, and a habitat island to preserve existing native vegetation stands. The project construction was completed in early November, 2007. Within two months of construction the project experienced several significant storm events. The bioengineered elements of the project held, and the channel operated as expected. A year from construction the vegetation, particularly the willow elements, continues to thrive and most structural elements are completely hidden by the native vegetation.
Note: Non-biological engineering vegetation was installed by CCBER.
