Orange County, CA

PACE provided a feasibility study for restoration and stabilization of Borrego Canyon Wash, which had been eroding at a significant rate and contributing sediment to downstream receiving waters.  A detailed understanding of the geomorphic characteristics for the existing watershed and floodplain stream corridor, quantitative analysis was utilized to understand the relationship between standard engineering hydraulic / fluvial principles to determine the relationship of the physical processes and river mechanics occurring within the active creek as part of developing a comprehensive restoration. PACE provided the following services:

  • Fluvial Modeling including both a sediment continuity or sediment balance on a reach-by-reach basis, and the application of complex unsteady state fluvial models using either HEC-6T or FLUVIAL -2.
  • Natural Stream Characteristics / Geomorphology Analysis to develop a basic understanding of the channel behavior including three perspectives: planform, cross section, and longitudinal view.
  • Creek Stabilization Alternatives Formulation to develop potential creek stabilization mitigation “alternatives” based on the results of the fluvial/geomorphic study and creek instability indicators associated with the study reach.   Alternatives included: (1) bank erosion treatments, (2) channel invert or grade stabilization requirements, (3) channel geometry, (4) channel profile, (5) geomorphic stream corridor restoration elements, and (6) bioengineering/vegetation bank stabilization.
  • Integration of Geomorphic Channel Restoration Features/Elements to design a stable channel.
  • Alternatives Feasibility Analysis to screen the number of conceptual alternatives according to (1) advantages, (2) disadvantages, (3) preliminary construction costs, (4) design constraints, (5) physical constraints, (6) implementation requirements, (7) flood protection, (8) economic factors including intangible costs, (8) environmental impacts, and (9) sediment reduction.
  • Application of Bioengineering Control Measures for slope stabilization and benefits of diverse riparian habitat, organic input into the stream, and shade to moderate water temperatures and improve water quality and site aesthetics.