Holdrege & Kull provided geotechnical design and construction engineering services for this emergency repair of a collapsed wing wall on the Lindo Channel Bridge (State Bridge number 12C-203) on the Esplanade in Chico. The three-span concrete arch bridge was built in the early 1900s and later widened on the west side around 1959. Sometime in early 2016, the southeast corner concrete wing wall toppled and left an approximately 14-foot-tall by 30-foot-long near-vertical fill slope exposed. The exposed slope required immediate mitigation to prevent further unraveling or slope failure.
H&K designed a mechanically stabilized reinforced earth and segmented block retaining wall structure to replace the wing wall and shore up and support the road and abutment fill. H&K used a drone to fly the site and take aerial photos that were used to prepare a three-dimensional rendering of the surface to get accurate grades and delineate notable features. The segmented wall was then designed using Ultra Block concrete products with geogrid strapping at each course level, and backfilled with clean crushed ¾-inch rock.
During construction, H&K provided engineering oversight and quickly responded to field conditions exposed during demolition that required modifications of the segmented wall location and layout. Layout changes were provided onsite and allowed for a field fit approach to completing the wall while avoiding critical underground infrastructure present in the area. H&K provided construction quality assurance testing and inspection services for the foundation embedment excavation, concrete block placement, crushed rock backfill placement, geogrid reinforcement installation, and compaction testing of engineered fill for the new sidewalk. H&K prepared final as-built drawings to document construction of the completed retaining wall.