Design for Restoration of James Creek between Jamestown and Left Hand Creek Confluence

Lynker, working with a team comprised of Otak, Ecos and Amec, developed a 30% stream restoration design for James Creek that supported a CDBG-DR implementation funding application and provided clear direction for detailed engineering and specifications. Lynker developed a conceptual model that describes and illustrates past, present and potential future conditions of the study sites from an ecological and geomorphic perspective.

Lynker then provided LWOG and stakeholders recommendations for appropriate restoration goals necessary to achieve a sustainable trajectory for the study reaches. The site conditions assessment was founded on a combined desktop and field investigation supported by development of a project specific GIS and subsequent spatial analysis. A project specific 1D (HEC-RAS) hydraulic model was developed in order to develop various design data products on demand (e.g. water surface elevations, stream velocities, shear stress and stream power). The model will be tightly coupled to Geo-RAS so that all these outputs could be rapidly developed and visualized spatially as a function of the selected design flow and in relation to stage and discharge through the reach.

Lynker then conducted field and desktop-based geomorphic analysis to assess key erosive and depositional processes and causes of lateral and vertical instability and existing controls in the study reaches, the results of this assessment being presented using Rivertsyles © to facilitate discussion of existing and proposed conditions. The team’s ecology specialist identified ecological restoration opportunities, Lynker’s design process built upon relevant prior analyses to assess the current and desired geomorphic condition to determine the most technically feasible and cost-effective resilient restoration alternatives that best matched stakeholders’ input, and technical and regulatory constraints.

Lynker then developed 30% designs to support a CDBG-DR implementation funding application, the designs providing clear direction for detailed engineering and specifications. Design development included geometries for compound channels that will provide fish habitat, cross-sectional stability, sediment conveyance, and overbank access across the range of design flows. The designs included revegetation options for optimal instream habitat benefit, long-term bank stability, and moderating water quality. Finally, the project team developed a draft monitoring and adaptive management strategy. A key part of this project was coordination with Boulder County and supporting LWOG with stakeholder meetings throughout the process of developing the design plans.