Various FEMA Projects

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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.


Storm Drain Master Plan

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Client: 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.


Flood Management Report and Design

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Client: City of San Mateo

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.


San Francisquito Creek Stormwater Pump Station

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Client: City of Palo Alto

The new San Francisquito Pump Station is located adjacent to San Francisquito Creek at the border of Palo Alto with East Palo Alto. For decades San Francisquito Creek has proven to be a contentious and often divisive boundary to the communities along its banks. After living through the February 1998 flood event of record and another flood event in 2002, Palo Alto voters approved a storm drain improvement bond measure. The first project to be constructed is the $7 million San Francisquito Creek Pump Station to alleviate local flooding caused by high creek tailwater. The pumping facility is designed to handle up to 300 cfs of local storm water runoff with submersible axial flow pumps discharging through an energy dissipating structure and a constructed wetland channel to provide mitigation habitat and prevent creek erosion. Electrical controls and a 1 megawatt standby generator are housed in a building designed to LEED standards. Schaaf & Wheeler helped the City lead the project through numerous regulatory approvals including those from Santa Clara Valley Water District; San Francisquito Creek Joint Powers Authority; the City of Palo Alto Architectural Review Board, the City of Palo Alto Building and Electric Utility departments; the neighboring City of East Palo Alto; and regulatory agencies including the U.S. Army Corps of Engineers, California Department of Fish and Game, and San Francisco Regional Water Quality Control. Initially slated for a City easement directly adjacent to the creek bank, the pump station was redesigned with a setback and newly created open channel discharge to protect the west bank of the creek from erosion, create wetland and riparian habitats, and allow for future bridge modifications and creek widening that would improve San Francisquito Creek flood capacity. Careful hydraulic analyses were completed to establish an automatic high creek level shutoff that prevents the pump station from inducing additional spill into East Palo Alto. The facility was dedicated on April 30, 2009.


Recertification of SCVWD Levees to Meet FEMA Mapping Standards: Uvas, Stevens, & Lower Penitencia Creeks

Client: Santa Clara Valley Water District

Santa Clara Valley Water District (SCVWD) participation in FEMA’s Map Modernization Program (MapMod) includes the accreditation of levees that provide protection from the base flood – the 1% annual flood also known as the “100-year flood.” Schaaf & Wheeler was engaged to evaluate, with the intent to certify, a total of 5.5 miles of Santa Clara County urban levees:
• Stevens Creek in Mountain View (Crittenden Lane to Highway 101)
• Lower Penitencia Creek in Milpitas (Interstate 880 to Berryessa Creek)
• Uvas Creek in Gilroy (2,200 feet downstream of Thomas Road to Santa Teresa Boulevard)

Schaaf & Wheeler lead a team of water resources engineers, geotechnical engineers and surveyors, tasked with: project management, meetings and partner coordination; levee reconnaissance, macro assessment and photo-documentation of levee settlement, vegetation, erosion, encroachments, slope instability, maintenance practices, seepage, distressed interior drainage structures, excess debris and animal burrows; cross sectional surveys and levee profiles; hydrologic reconciliation; hydraulic modeling for each levee recertification reach; evaluation and certification of levee freeboard; field exploration, laboratory analyses, geotechnical evaluation and certification; interior drainage studies; submission of Levee Recertification Package to FEMA; and additional floodplain mapping in Mountain View.

On October 13, 2009, FEMA found each of the levees to meet all requirements for full accreditation under 44CFR65.10.


Foster City Levee Planning and Improvements Project (CIP 301-657)

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Location: Foster City, CA

Foster City is protected from flooding by approximately 8 miles of levees that surround the perimeter of the city. Schaaf & Wheeler is providing the City with a comprehensive framework as to how its flood risk is impacted by the newly released coastal study results for San Francisco Bay and a recent levee crest survey. Without action, 17,000 properties in Foster City and San Mateo will be placed in high-risk Special Flood Hazard Area and property owners with federally backed loans will be required to buy flood insurance at higher rates. Schaaf & Wheeler is providing planning and engineering services to regain FEMA levee accreditation; obtain the regulatory approvals necessary to construct levee improvements; design adaptive measures for the levee system appropriate to future estimates of sea level rise and the uncertainty inherent in those estimates; and establish the costs for levee improvements to enable the formation of an assessment district to fund them.


Marsten Storm Water Pump Station

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Client: City of Burlingame

The Marsten Storm Water Pump Station is a replacement pump station funded by a City-wide parcel tax approved by the voters to correct a number of drainage issues within the City. The new pump station receives water from two sources: local storm drain discharge and diverted creek flow. Water from both sources discharges to a common 66-inch force main which outfalls to Easton Creek downstream of Old Bayshore Blvd. The station is designed to convey flows corresponding to a 30-year storm event – 122 cubic feet per second from the local storm drain system and 162 cubic feet per second from the Easton Creek diversion. To minimize the chance of flooding from the creek and to reduce the overall station horsepower, the two sources of stormwater do not mingle and are pumped by independent pumps. Pump station components that are critical and that need to be protected from potential site flooding were designed to be above historical site flooding levels so that the station can remain functional if flooding should occur. Shaft-driven axial flow pumps were chosen for the station to meet the low discharge heads and to minimize discharge piping requirements while keeping construction costs low. Scope of services included hydraulic modeling of Easton Creek to determine creek diversion flows, alternative station layouts, coordination with City engineering and maintenance departments, construction document preparation, coordination with the City’s environmental document consultant, document modifications for cost saving measures, bid support and construction support services.


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