This project consisted of a bank stabilization to protect a petroleum pipeline crossing along a stretch of Donner Creek, near the Town of Truckee, California. 7Q10 was able to assess the geomorphologic requirements, obtain the necessary environmental permits, draft construction documents, supervise the construction activity for stream bed/bank protection and monitor project results.
To more fully understand the project, 7Q10 estimated peak flows and flow durations based on hydrologic considerations for Donner Creek (controlled releases from Donner Lake) and outflow from Cold Creek. 7Q10 then determined the shear stress necessary for substrate mobilization based on pebble count data. Critical shear stresses were based on the necessary shear stress to transport bed material from the substrate. A surface water profile model, HEC-2, was used to determine the distribution of shear stresses for existing conditions for various flow rates in Donner and Cold Creek (used: expected flow duration from current two-year to 100-year flows). The combination of flows represented the hydrograph at the project site.
Input data for the analysis were gathered from a field survey of 12 cross-sections and a pebble count of existing substrate. Shear stresses on existing conditions were used to estimate current thresholds of scour or particle movement. Through this modeling effort a bank stabilization project was implemented within Donner Creek, including considerations to achieve water quality objectives as defined by the RWQCB- Lahontan Region. The bank stabilization was tested during the floods of January 1997 and remained intact while other portions of the creek were destroyed by severe erosion. In November 1997, 7Q10 conducted another bank stabilization project upstream and downstream of the 1995 project site, providing further stabilization for the petroleum pipeline.