Laguna Creek Restoration Project
Vulcan Materials Company is actively mining aggregate at the Triangle Rock Products facility in Sacramento County adjacent to Laguna Creek and within the creeks active floodplain.
To mitigate for impacts to jurisdictional waters and special status species resulting from expansion of the facility south of Florin Road, and as part of a phased Reclamation Plan, Vulcan is required to enhance the Laguna Creek corridor and preserve existing vernal pools west of Laguna Creek. As part of the creek corridor enhancement, a meandering channel planform will be reintroduced to include a lower emergent marsh terrace (18.5 acres) and a higher upland riparian terrace (6.2 acres). The creek enhancement also includes a flood weir to reduce flood impacts by diverting floodwaters into a reclaimed pit.
The design-build team consists of WRA (project management, permitting, ecological design/monitoring), cbec (field services, stream rehabilitation design/monitoring, construction observation), and Hanford ARC (construction, monitoring/maintenance). Under Phase 1 of the rehabilitation design, approximately 70% will be rehabilitated prior to expansion into the final parcel, with the remainder of the rehabilitation to be completed after mining is complete after several years. To inform the design of the creek corridor, cbec collected stage and flow data for two winters, reconstructed a long-term flow record based on nearby gage correlation, performed ground surveys, and coordinated the geotechnical exploration. This data was then used to size the low flow channel based on geomorphic principles using state-of-the-art approach (NCHRP Research Report 853 [Bledsoe et al., 2017;]), design for the hydro-regime of the emergent marsh, and update / calibrate the County maintained HEC-RAS hydraulic model. The hydraulic model was used to iteratively inform the design of creek corridor plan /profile as well as evaluate the flood conveyance performance of the phased and full buildout conditions and the preliminary design of the permanent flood control weir.
Construction is complete as of late July 2020, and equipment has demobilized. Installation of irrigation, erosion controls, seeding and planting will commence in August 2020.