Jo Beth Folger FAC CF Breakout - April 8, Site Conditions and Geotechnical Data Presentation Outline Site Overview Historical Data LCLS Investigation Future Work

Jo Beth Folger FAC CF Breakout - April 8, SLAC Site Geologic Overview Miocene Ladera Sandstone, overlain by Santa Clara Formation and native fill Very soft, very weakly cemented (by clay) sandstone, with strongly cemented (by calcium carbonate) thin interbedding locally Nearest major fault is the Peninsula Segment of the San Andreas Fault, 5 miles SW Groundwater is not expected at LCLS depths

Jo Beth Folger FAC CF Breakout - April 8, Historical Geologic Data Numerous geologic studies at the site since the late 1950’s 2 mile long Linac – 1959 Positron Electron Project (PEP) tunnel – 1975 Stanford Linear Collider SPEAR – 1982 Almost 200 boreholes drilled by 1994 At least 32 geologic reports written by 1994

Jo Beth Folger FAC CF Breakout - April 8, Geologic Map with LCLS Boring Locations

Jo Beth Folger FAC CF Breakout - April 8, Groundwater Elevation Contours 240’ contour 180’ contour LCLS Elev ’

Jo Beth Folger FAC CF Breakout - April 8, LCLS Geotechnical Investigation Two Phases Summer 2003 and Summer 2004 Rutherford & Chekene 12 soil borings Sample Analyses Dry Density Moisture Content Unconfined Compression Consolidated Undrained Triaxial Petrographic Analysis Slake DurabilityParticle size Shrink/swell expansion pressure Cerchar abrasion Creep R-value Corrosion potential In-Situ Testing Background vibration measurement Shear wave velocity ~1,800 feet/sec Compression wave velocity ~4,100 feet/sec Pressure meter testing/ insitu deformation modulus - Deformation parameter varied from 1,000 bars to 12,500 bars, indicating interbedded layers of soft and hard rock Seismic Analysis

Jo Beth Folger FAC CF Breakout - April 8, LCLS Boring Locations 12 AB 3a,b C 4 DE 5 6

Jo Beth Folger FAC CF Breakout - April 8, Analytical Results

Jo Beth Folger FAC CF Breakout - April 8, Analytical Results cont.

Jo Beth Folger FAC CF Breakout - April 8, Tunneling Memorandum Summary Tunneling will occur entirely in Ladera Sandstone Formation Tunneling condition categorized as “fair to poor soft rock” Suggested construction method – roadheader excavation, followed by shotcreting Horseshoe tunnel cross section Stand open time and advance rate discussed

Jo Beth Folger FAC CF Breakout - April 8, Future Work Support structural engineering effort – ongoing Produce Geotechnical Baseline Report – bids received, award planned 4/8/05