CS31F - Concurrent Session 31F: SREL C3 – Construction Challenges and Solutions

Sacramento River East Levee (SREL), part of American River Common Features (ARCF) 2016 Project, is being executed by USACE under four (4) different contracts. The project assumes significance due to its location and important from public safety and asset protection standpoint. The Contract 3 completed in 2022, involved construction of two (2) miles of cutoff wall. The construction of Contract 3 flood protection features is intended to reduce the flooding risk to the critical infrastructure in downtown Sacramento. JV Partners Kleinfelder and Stantec supported the USACE Sacramento District (SPK) on the design of SREL Contracts 3 and 4. The team provided civil and geotechnical engineering-related design services during the construction of various design features. The JV team supported the engineering services during construction on Contract 3

The paper discusses the challenges encountered and solutions adopted during the construction of 2,730 feet of deep mixing method (DMM) cutoff wall, 5,900 feet of soil-bentonite (SB) wall, 1100 feet of Slag-Cement-Cement-Bentonite (SCCB) wall, and earthwork during reconstruction of the levee. The DMM wall encountered challenges due to use of air pressure through the drill stems, multiple instances of stuck augers in the ground, and impact on mixing index due to a broken paddle on the auger. The challenges with open trench soil-bentonite (SB) and Slag-Cement-Cement-Bentonite (SCCB) walls included confirmation of the tie-in layer, interpretation of trench sounding data, slurry leak, and quality control issues. The paper emphasizes the importance of construction sequencing and challenges encountered at the tie-in locations of different walls. The paper also discusses the challenges to reconstruction of levee embankment and the solutions adopted to overcome the varying stratigraphic conditions at the degrade elevation and different cutoff wall types creating varying challenges to the reconstruction of the levee.