Two levees owned by the City of Arcata were damaged by intense wind, rain, and tidal surges during winter storms that occurred in the 2005-2006 season. These levees separate Humboldt Bay from Arcata’s wastewater treatment ponds and Klopp Recreation Lake. They are critical for protecting the treatment facilities, public health, and beneficial uses of Humboldt Bay.
LACO’s project team led and collaborated with City staff and the project contractor, Magnus-Pacific Corporation, to bring the repair projects through the funding, permitting, design, and construction phases. The City obtained funding through FEMA and the California Governor’s Office of Emergency Services (CalEMA) administered the project.
The levees were originally constructed of bay mud materials beginning in the 1950’s. Concrete and asphalt-concrete waste debris was added later as armoring. The storm damage provided an opportunity to upgrade the levees to current construction standards. Our project team selected rock slope protection (RSP) to armor the levees based on its reliability, longevity, ease of permitting, and economy. Repairs included removal and recycling of existing debris within the project backfill, excavation of a toe trench, installation of geotextile fabric, and placement of the RSP armoring system. The levee tops were widened for access within the existing levee footprints, and heightened to minimize overtopping risks during future storms.
We met a number of unique challenges throughout this project. The Wastewater Treatment Plant levee was repaired without interrupting wastewater operations, and the sensitive Klopp Lake levee remained open and accessible to recreational users as much as possible. The Klopp Lake levee is located within the greater Arcata Marsh and Wildlife Sanctuary (AMWS), a destination regularly visited by wildlife groups such as the Audubon Society. These organizations provided an extra level of scrutiny and oversight to the implementation of the projects. The residents in and around the City of Arcata are the greatest users of the AMWS, and the public process used to notify and educate the community was extensive.
Repair work was restricted to the existing levee footprint to meet funding and permit agency requirements, thus limiting space to provide needed structure and top width for vehicle access in several locations. Access along the Klopp Lake levee was inadequate, requiring widening and extraordinary traffic measures. Protection of water quality was a critical project element, and turbidity curtains and silt fences were especially effective in containing suspended sediment which resulted from either the excavation of the slope and toe trench or placement of RSP within the water. Existing concrete debris was removed, crushed on site, and reused as granular backfill within the levees. Asphalt-concrete debris was recycled offsite.
We also coordinated and obtained numerous permits and approvals from agencies including the California Coastal Commission, US Army Corps of Engineers, Humboldt Bay Harbor Recreation and Conservation District, US Fish and Wildlife, California Department of Fish and Game, National Oceanic and Atmospheric Administration Fisheries, and the North Coast Regional Water Quality Control Board.
The City attributes the project’s success to:
- Clearly stating the project constraints during the design phase
- Selecting the engineering firm equipped and willing to work with the many challenges of the project from design through construction
- Securing a competent and experienced contractor to perform the work
- Having a multidisciplinary team of City staff dedicated to the successful completion of the project and who interfaced with the engineer and contractor on a regular basis