North Area Streams Levee Improvement

The northern area of Sacramento relies on several miles of levees and channels for critical flood protection. These levees have been a cornerstone of the region’s defense against flooding. In the 1990s, the levee system underwent significant upgrades to enhance its ability to protect against rising waters. However, after the catastrophic flooding in New Orleans due to Hurricane Katrina in 2005, state and federal agencies revised their safety standards. These new regulations sought to make levees across the country even safer and more resilient.
 
A comprehensive geotechnical data report prepared for the Sacramento Area Flood Control Agency (SAFCA) revealed that several segments of the levee system did not meet the new, stricter standards. The report underscored the urgent need for seepage control and improvements in levee infrastructure to maintain effective flood protection. Without these upgrades, the levees would not be able to provide the necessary level of safety and could be at risk of failure during extreme weather events.
 
The challenge was significant, as the existing levee system required upgrades to meet these new standards. This situation presented a complex problem involving significant geotechnical work, advanced engineering, and a coordinated effort across multiple stakeholders. The need for substantial improvements in levee construction was clear, especially to ensure the ongoing protection of the northern Sacramento area from severe flooding.

SAFCA selected our joint venture team to undertake this critical project. The task was to improve 2.3 miles of levee along the Natomas East Main Drainage Canal (NEMDC) East Levee and Arcade Creek. We faced an aggressive construction schedule, from May to November, which required precise planning and execution to meet the deadlines.

To address the seepage issues identified in the geotechnical report, we constructed extensive soil-bentonite (SB) and slag-cement-cement-bentonite (SCCB) cutoff walls, totaling 191,968 square feet of SCCB and 211,254 square feet of SB cutoff walls. The cutoff walls served as barriers to prevent water from seeping through and under the levee, which could undermine its integrity and lead to potential failure.

During the construction process, our team managed various utility and structural conflicts. These included navigating active high-pressure gas lines, a 66-inch sewer main, 30-inch potable water lines, and fiber optic lines . Our team had to work around a stormwater RCP pipe, bike trails, a bridge with a clearance of 15 to 17 feet, and a main thoroughfare that serves homes, businesses, and schools. Additional work elements included the reinstallation of three sump structures and one gate riser structure that contained a total of ten pipe modifications ranging from 12 to 54 inches, five RCP structure modifications, and an 8-inch City potable waterline. Each of these elements required careful planning and coordination to ensure that the construction did not disrupt critical infrastructure.

We also undertook the removal, bypassing, and replacement of three major stormwater pump stations for the City of Sacramento, as well as a main water line. Despite these challenges, we maintained the operational integrity of all utilities and structures throughout the project. Our ability to manage these complex challenges while keeping essential services running was a testament to our expertise in levee construction and infrastructure management.

Our efforts involved excavating 175,817 cubic yards of levee embankment and 45,148 cubic yards of borrow site material. These actions facilitated the construction of cutoff walls and other necessary levee improvements. The project required the cooperation and contribution of multiple stakeholders, including SAFCA, the California Department of Water Resources, the United States Army Corps of Engineers, the City of Sacramento, and Sacramento County. This collaborative effort was essential for the project’s success.

The improvements we implemented significantly enhanced the stability of the levees and protected critical infrastructure from potential flood damage. The upgrades provided essential erosion control, bolstering the flood resilience of the region through effective slurry wall construction and levee enhancements. These measures ensured that the levees could withstand increased water flow during natural disasters, meeting the modern standards set by SAFCA and federal guidelines.

Our team’s commitment to managing complex challenges and maintaining operational continuity throughout the construction process led to minimal disruption to community services and infrastructure. This approach ensured that the project goals were met efficiently, while also maintaining safety and functionality throughout all phases of the work. We demonstrated our dedication to serving the community and enhancing infrastructure through advanced geotechnical construction methods.

This project highlights the crucial role of seepage control, cutoff wall construction, and robust levee infrastructure in protecting urban areas from severe flooding. By meeting modern flood prevention governance, we have ensured that the levees in northern Sacramento are capable of providing the highest level of protection against future flooding events, safeguarding both the environment and the community.