Flood Protection in Milpitas
In the summer, Berryessa Creek is mostly dry except in Milpitas, where much of its water comes from urban runoff and tributaries. In winter, however, the creek can flood very high and pose a hazard for surrounding residences.
Berryessa Creek is a seasonal creek that runs through the cities of Miltipas and San Jose. Although normally dry in the summer, the creek can cause flooding during the winter rainy season, endangering more than 1,800 local homes. To reduce the risk of flooding to the neighboring community, the Lower Berryessa Creek Flood Protection Project extends approximately 1.7 miles through Milpitas, from its confluence with Lower Penitencia Creek, south to Calaveras Boulevard. The project also included more than two miles of Calera and Tularcitos creeks. These two smaller creeks are tributaries to Berryessa Creek and must also be modified to prevent water from overflowing their banks.
Levees and Floodwalls
The project was completed in two phases. The first phase stretches along Lower Berryessa Creek, from the confluence at Lower Penitencia Creek to Abel Street, and was completed in December 2016. Flood protection improvements included earthen levees on the east and north sides of the creek and concrete floodwalls on the west and south sides of the creek. To further reduce the potential for flooding, wetlands were replanted and established within the creek channel.
The second phase has two segments. The first segment was along Lower Berryessa Creek, stretching from Abel Street to Calaveras Boulevard. The flood protection improvements for this segment included improved earthen levees on the north side of the creek and concrete floodwalls on the south side of the creek. A riparian habitat area was also included within the creek channel. These major construction activities were completed in 2018. The second segment of Phase 2 is along Calera Creek, stretching from the Lower Berryessa Creek confluence to Milpitas High School. The first section from Milpitas High School to Arizona Avenue was completed in 2021 and included a raised U-frame channel and concrete floodwalls on both banks of the creek. As with the first phase wetlands with native vegetation were established within the Calera Creek channel to further reduce the risk of flooding.
The flood protection improvements along Lower Berryessa Creek between Abel Street to Calaveras Boulevard were completed in July 2020. The project’s final phase of construction on the Calera Creek segment, located between Arizona Avenue past North Milpitas Boulevard to the Bay Area Rapid Transit (BART) railroad tracks, is expected to be completed by December 2022.
Mitigating Risk and Reaching Project Delivery Goals Through Efficient Construction Management
Ghirardelli Associates (Ghirardelli) provided construction management services for the District to administer the contracts between the District and its contractor and to manage and control the project risks during construction including cost, schedule, quality, and safety. Our assigned Resident Engineer was the primary point of contact between the contractor and the District, and our inspectors monitored and prepared daily inspection reports to document field activities to verify that the work was in compliance with the plans and specifications. The Resident Engineer organized and conducted the weekly progress meetings and was responsible for schedule management, processing monthly progress payments, RFI and submittal management, negotiating change orders, and monitoring the contractor’s compliance with safety requirements. The Resident Engineer and inspection team worked closely together to identify and resolve potential issues early to minimize cost and schedule impacts.
