Lake Isabella Dam Home

Lake Isabella Dam

US Army Corps of Engineers, Sacramento

Situation Report December 5, 2008

QUICK SUMMARY (TAKEAWAYS): Kern Canyon fault trenching investigations continue at sites downstream and upstream of the reservoir.  Drilling investigations will also continue in December on both the main and auxiliary dams. Events             Recent event(s)  None to report. On-Going Investigations Update Inundation Mapping – Transmittal letter to the Kern County Office of Emergency Service for the final inundation maps for the Town of Lake Isabella and Bodfish and the additional work for downriver inundation scenarios continues with delay for review and signature. U.S. Geological Survey (USGS) Geophysical Foundation Study – Awaiting comments from the Independent Technical Review (ITR) (see below) to finalize the report. No change to report. Geophysics Independent Technical Review – Period of performance extended until December 31, 2008 due to illness of reviewer.  Auxiliary Dam Site Characterization – Corps comments have been sent to the AE for incorporation in the final report.  Interim Risk Reduction Measures Plan (IRRMP) – The draft report will be sent to Omaha District for completion. Structures Data Collection – Comments on the draft memorandum provided, report being finalized. Structural Seismic Analysis – Efforts continue on-schedule. Economics – Scoping efforts continue for floodplain and hydrologic analyses needed. US Forest Service (USFS) Coordination – The Corps met with the USFS at Lake Success on November 17th to discuss project activities, funding and the agreements.  The Ancillary Operating Agreement No. 4 signed by Colonel Chapman was hand delivered to the USFS.  The next meeting is scheduled by video teleconference on December 9th.  // Funding discussions continue between management and the USFS.  Interim funding has been provided. Kern County Fault Investigation (LiDAR) (Light Detection and Ranging – a remote sensing system used to view fault scarps) - the First Phase Report was delivered 25 August 2008.    The first phase has been invaluable and has revealed many, many fault scarps not able to be seen in field work.  Phase II data delayed delivery to 30 October 2008.  Period of performance extended and contract modified to add flight and additional data collection of the north end of the fault.  Contract mod awarded 31 October 2008 to Towill.  Northernmost area was not flyable due to snowfall.  The task order will have to be extended until next summer for data collection after the snow melts.  This delay will not affect the overall project schedule. Auxiliary Dam Upstream Foundation Investigation – No change to report. Site Visit/Planning Charette – Report finalized, resulting scoping actions moving forward, see FY2009 planned efforts below. Rock Coring on Auxiliary Dam – Omaha District delayed, mobilized equipment on November 20th, and returned December 3rd to begin drilling on the Auxiliary Dam.  USBR is scoped with two rock triplets (total 6 holes); drilling is slow and deeper depths than anticipated have been required, a revised SOW has been funded, work scheduled to be completed in January 2009. Main Dam Site Characterization and Seepage Evaluation (Phase B) – Slight delay by Contractor, scheduled to be recovered for report due in March 2009. Kern Canyon Fault Characterization (trenching) –Rights of Entry actions continuing.  Coordination efforts with the USFS continue regarding land access and required environmental and cultural compliance efforts.  NEPA compliance ongoing for trench locations at Brush Creek and Rincon Springs sites.  Contract options awarded November 18th for additional trenching below the Auxiliary Dam and the Gold Ledge Creek Site.  Aux Dam Drain Blanket Drilling – Kansas City District has been scoped and funded to complete efforts, they are to arrive on site on December 5th.   FY 2009 Planned Efforts Pipe Repair – Award of this Contracted action is scheduled for December.  Actual work is scheduled to take three days in January 2009.  Borel Canal Repairs – No change to report. Flood Frequency Analysis – Corps team continue to work on scoping this effort to support the economic analysis.    Detailed Risk Analysis – The Scope of Work continues to be delayed but is in progress. Close Vehicle Access to Downstream Toe of the Auxiliary Dam – These efforts are being coordinated with the USFS to avoid impacts to cultural resources when moving the material from the main dam to the downstream location of the Auxiliary Dam. Floodplain Mapping – Scoping efforts continue. Security Cameras – No change to report. Telephone Equipment – Contracting efforts continue in support of this task. Conduit and Spillway Coring Sampling – Scoping efforts continue with the US Bureau of Reclamation; work is scheduled to begin in February 2009. Cultural Surveys Flood Frequency Determination Update Seismic Hazard Analysis Revise Deformation Analysis Spillway Erosion Study Spillway Remediation Alternatives – Scoping is in progress with the Joint Venture.  The seismic and seepage remediation is contingent on the spillway remediation alternative.  Alternatives will likely include widening and or gates (which would provide borrow for seismic remediation), and adding height to the dams to prevent overtopping in the Probable Maximum Flood (PMF).  Recently completed (contract) stage-frequency analysis indicates overtopping is a 1/750 annual probability. (no change) Remediation Alternative Formulation – Scoping efforts began in November with the Joint Venture to begin the preliminary formulation of remediation alternatives based on the data collected as part of the site characterization efforts.  Environmental Impact Statement/Report – Scoping efforts began in November with Joint Venture for the baseline studies, impact analyses, public notification efforts and reporting needed as part of the evaluation of the alternatives to be formulated for the project. These tasks are being initiated now to minimize any schedule delays that may arise due to NEPA compliance for remediation alternatives.   Funding Under the Continuing Resolution Authority (CRA), a total of $1,569,200 has been received to date in FY09.  Coordination The Corps continues to communicate and coordinate with various entities, including the local water user agencies, Kern County, the City of Bakersfield, U.S. Forest Service, and State and Federal legislative parties. Milestones/General Schedule of Completion Dates Site Characterization Completion - A list of preliminary remediation alternatives is scheduled for Winter/Spring of 2009. Detailed Risk Analysis FY 2009 Design Alternatives Analysis (incl. Alternatives Analysis, Environmental Impact Study, and Decision Document):  FY 2011 Final Design of the selected and approved alternative FY 2013 Construction of the project FY 201