On December 31, 2022, after several days of an “atmospheric river”, the 72-inch culvert passing underneath the entrance road to the Oakland Zoo suddenly and unexpectedly collapsed during extremely heavy flows, washing away a 25-foot-wide section of the road and exposing utilities. All operations and public access to the Oakland Zoo were shut down as a result of the damage. The zoo closure was prominently discussed on most of the Bay Area television and print-news outlets. The CEO of the zoo reported that the economic loss from the Zoo closure resulted in a loss of $500,000 per week due to the cancellation of the very popular Zoofari winter nighttime attraction. The collapse closed operations at the Zoo until the repair was completed.
ENGEO performed permitting support, monitored the creek during storms and heavy flow, prepared construction plans, and performed testing–and–observation services for the project. ENGEO also performed hydraulic calculations and developed plans and a list of bid items for removal of the failed culvert and construction of the new culvert.
The primary challenge was repairing the failed culvert and opening the access road in a rapid manner during an extremely wet weather pattern. The creek experienced high flows from large storms that occurred while the repair was designed; these high flows threatened to cause further erosion which may have damaged the exposed utilities that crossed over the former culvert and were now exposed. The emergency repairs required permits from Federal and State of California agencies.
As the City’s consultant, ENGEO quickly assisted City of Oakland Staff and their on-call Contractor (McGuire and Hester) in assessing the conditions, stabilizing the area of the failure so it would not worsen, monitoring the conditions during on-going storm events, and obtaining emergency permits from Federal and State agencies to replace the culvert and repair the road. ENGEO, the Contractor, and the City worked collaboratively to efficiently develop repair recommendations, prepare construction plans and specifications, and perform construction quality control services for the project. The repairs, which included removal of the damaged culvert, construction of a new culvert, backfill, and reconstruction of the road, were performed primarily during breaks in a heavy cycle of storms that impacted California in January 2023. The entrance road was completed in approximately 3.5 weeks and the Zoo was able to re-open to the public in just over one month (35 days).
