Orange County Branch Newsletter
ASCE OC Branch and Geotechnical Institute – East Garden Grove-Wintersburg Channel Project
By: Clint Isa, PE
ASCE-Orange County Branch and Geotechnical Institute co-hosted a luncheon at the Center Club in Costa Mesa on September 18th. The luncheon included a presentation regarding the geotechnical aspects of the East Garden Grove-Wintersburg (EGGW) Channel, which was given by Mr. Phil Jones, PE and Mr. Ali Fayad, PE, both of the Orange County Public Works Department - Flood Control Division.
Mr. Jones and Mr. Fayad were invited to discuss some of the many geotechnical features of the award-winning $43 million project that provided a seismic retrofit of the EGGW Channel. Mr. Jones’ portion of the presentation focused on the evolution of the final retrofit design based on geotechnical considerations. He first provided some background information on the roles of the various OC Public Works departments that directly contributed to the EGGW Channel improvements, and gave a brief history of the performance of other similar channels in OC during heavy rainfall events. Mr. Jones then proceeded to discuss the key considerations that necessitated designing the channel improvements for a seismic event in conjunction with a rain storm; such considerations included the potential impact of a channel failure on the adjacent, low-lying densely-populated residential areas, and fault traces that crossed the project alignment in several locations. Mr. Jones concluded his portion of the presentation by summarizing the findings of eight separate geotechnical studies performed for the project over the course of 10 years, and described the evolution of the channel improvements from tandem reinforced concrete box culverts to a hybrid design consisting of sheet piles and deep soil cement mixing (DSCM) based on the various design considerations.
Ali Fayad, P.E., Penny Lew, P.E. and Phil Jones, P.E.
During his portion of the presentation, Mr. Fayad discussed the project’s construction sequencing and validation, and some of the associated challenges. The challenges included significant access restrictions, which impacted the layout and design of the DSCM columns, and environmental (noise and vibration) restrictions that were addressed by using press-in equipment to install the steel sheet piles. Implementation of the improvements also needed to consider temporary surcharges generated by the construction equipment and the overall project geometry, which included portions of the DSCM columns that were installed 10 to 15 feet above adjacent grades. Mr. Fayad then went on to describe the process of designing and implementing DSCM construction validation guidelines, which were complicated by the lack of precedent for the proposed layout. Finally, Mr. Fayad gave a brief summary of the performance of the channel improvements during the seismic and rainfall events that occurred earlier this year.
Special thanks to our luncheon sponsors Jeffrey Wykoff (CNCement) and Rick Walsh (Hayward Baker) for their generous support!
Mr. Jones’ and Mr. Fayad’s presentation: