WMH Corporation, Inc. April 29, 2014 50 West San Fernando Street, Suite 950 Project No.: 2013-105-WCB San Jose, CA 95113

Attention: Mr. Tim Lee

Subject: Surface Fault Rupture Displacement Hazard (SFRDH) Analysis for Bridge Structures Widening of Walnut Creek Bridges – Bridge Numbers: 28-0240L/R (CC-4-13.4) (within Alquist-Priolo Earthquake Fault Zone) I-680/SR-4 Interchange Project - Phase 3 (SR-4 Widening), Contra Costa County, California

Dear Mr. Tim Lee:

As requested, we are providing this memorandum for the “Surface Fault Rupture Displacement Hazard (SFRDH)” analysis for the widening of Walnut Creek Bridges that are part of the “I- 680/SR-4 Interchange Project – Phase 3 (SR-4 Widening)” (Phase 3 Project).

SUMMARY

Caltrans bridges 28-0240L/R are located approximately 2 miles north of downtown Concord, Contra Costa County (CC-4-13.4; Plate 1). The bridges are within the Alquist-Priolo Earthquake Fault Zone (EFZ) for the Concord fault (Plate 2). The Walnut Creek Bridges straddle the mapped Main Trace of the Concord fault. The mapped East Trace of the Concord fault is located approximately 230 meters (755 feet) east of the Main Trace.

The Concord fault is capable of moderate displacements, but the probability of off-fault displacements decreases rapidly with increasing distance from the fault. We expect moderate displacements to occur along the Main Trace of the Concord fault within the bridge footprint. Conservatively, we have assumed that all of the potential slip will occur along the Main Trace of the fault. The potential off-fault horizontal displacements within the bridge footprint are; 0.22 meters (8.7 inches) deterministically and 0.57 meter (22.4 inches) probabilistically. Vertical displacement of approximately 10% of the horizontal value, which is up to 0.06 meters (2.7 inches), should be assumed to occur along with the horizontal displacements. The two bridges are parallel to one another and perpendicular to the Concord fault. Therefore, the results of the analyses are identical and this memorandum presents the results for both bridges.

Per Memo to Designers (MTD) 20-8, the larger of the deterministic and probabilistic values or a site-specific value should be used for design.

2360 Qume Drive, Suite A, San Jose, CA 95131 l P (408) 452-9000 l F (408) 452-9004 l www.PARIKHnet.com San Jose ♦ Oakland ♦ Walnut Creek ♦ Sacramento ♦ Fresno

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INTRODUCTION

This evaluation was prepared for the Widening of Walnut Creek Bridges as a part of I-680/SR 4 Interchange Project - Phase 3 (SR 4 Widening) in accordance with Caltrans policies outlined in MTD 20-8 and MTD 20-10. Caltrans requires a fault rupture evaluation if a bridge is located within an Alquist-Priolo Earthquake Fault Zone or within 1,000 feet of an un-zoned fault 15,000 years or younger in age. Caltrans policies regarding evaluation of fault rupture hazard at bridges are described in MTD 20-10.

The Walnut Creek Bridges cross the mapped Main Trace of the Concord fault at approximately a right angle within the Alquist-Priolo Earthquake Fault Zone (EFZ) for the Concord fault (Plate 2). The mapped East Trace of the Concord fault is located 230 meters (755 feet) east of the mapped Main Trace. That is 174 meters (570 feet) east of the eastern abutments of the bridges.

The SR-4 Bridges over Walnut Creek (Bridge Numbers: 28-0240L/R, County Route 4, MP 13.40) were built in 1981. They are 5-span slab bridges on reinforced concrete pile bents with reinforced concrete abutments.

Our evaluation of the surface fault rupture displacement hazard at the Walnut Creek Bridges included review of published literature and consultants’ reports, evaluation of topography and air-photos, discussions with experts, and a site reconnaissance. Since the bridges are parallel and are perpendicular to the Concord fault, we performed deterministic and probabilistic calculations of potential off-fault displacements within the footprints of both bridges in compliance with MTD 20-10 utilizing the Excel-based worksheet provided by Caltrans. This memorandum presents the findings and results for both bridges.

PUBLISHED LITERATURE AND CONSULTANTS’ REPORTS

Poland (1935)

Poland (1935) recognized the presence of a fault in the Ygnacio Valley (southern Concord) based upon depth-to-groundwater data that indicated the presence of a linear subsurface barrier to flow of groundwater. He named it the Concord fault and showed it trending N 30 degrees West on the map in his Stanford University Master’s thesis.

Sharp (1973)

Sharp (1973) mapped the Concord fault based upon surface evidence of creep. Beginning north of Suisun Bay, Sharp projected the Concord fault southeastward across the bay, through the marshes at the mouth of Pacheco Creek and along the base of the west-facing flank of “Tank Farm Hill” east of Buchanan Airfield (coincident with the man-made linear channel of Walnut Creek). Sharp’s map points to evidence of right-lateral (“RL”) displacement on Waterfront Road (approximately 13,400 feet northwest of the subject SR-4 bridges), noting a “bend in bridge on

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Waterfront Road consistent with RL movement near W abutment” and where a Santa Fe Railroad bridge crosses the Walnut Creek channel (approximately 7,000 feet northwest of the subject SR-4 bridges), noting “RL warping of railroad bridge built in 1965”. However, in 1973, where SR-4 crossed Walnut Creek on a bridge built in 1938 (now called the Marsh Road Bridge), Sharp noted “bridge no obviously deformed by RL offset”. South of SR-4, Sharp noted “Possible old SW-facing scarp” where Solano Way parallels the linear channel of Walnut Creek and “Probably natural sag, now destroyed by grading” where the channel bends toward the west (subsequently developed as Stanwell Drive). At Concord Avenue (approximately 9000 feet southeast of the subject SR-4 bridges), Sharp noted the railroad “track not offset” and “small RL offset of curb”. Further southeast, Sharp mapped two parallel fault traces several hundred feet apart with numerous notations of evidence of fault creep.

Burkland and Associates (1974) AP-0062

Burkland and Associates conducted a fault investigation of the site of the proposed Deutscher Company Warehouse at the intersection of Solano Way and the Southern Pacific Railroad tracks. (The site is labeled with the number “0062” on the attached Plate 3.) The investigation included several magnetometer and seismic refraction surveys and three trenches. Their findings led Burkland and Associates to conclude that no active faults cross the site. (Consequently, those findings suggest that the Main Trace of the Concord fault is located west of this site.)

Burkland and Associates (1973 – 1976) – AP-0001.1 through AP-0001.4

Burkland and Associates conducted fault investigations at several places within the Stanwell Drive Office complex (located between 5,000 and 7,000 feet southeast of the subject SR-4 bridges). (The site is labeled with the number “0001” on the attached Plate 3.) The investigation included trenches that exposed the main trace of the Concord fault within a 30 to 50 foot wide zone trending northwest across the sites and projecting northwestward beneath the linear portion of Walnut Creek toward the subject SR-4 bridges.

ENGEO, Incorporated (1977) – AP-0001.5

ENGEO (1977) also trenched across the Main Trace of the Concord fault within a portion of the site located near the north end of Stanwell Drive. (The site is labeled with the number “0001” on the attached Plate 3.) ENGEO exposed the fault in trenches and confirmed the location of the surface trace as previously mapped.

Woodward-Clyde Consultants (1979) AP-0001.6 and AP-0001.7

Woodward-Clyde Consultants (1979) trenched across a site located west of Stanwell Drive. (The site is labeled with the number “0001” on the attached Plate 3.) Woodward-Clyde Consultants concluded that the Concord fault does not cross the then proposed building location.

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Harding Lawson Associates (1982) – AP-0001.8

Harding Lawson Associates (1982) also trenched the site at the north end of the Stanwell Drive cul de sac and found the eastern edge of the Main Trace of the Concord fault essentially as previously mapped.

ENGEO (1977) – AP-1741

ENGEO conducted a fault investigation on the site of the then proposed Kiewit Office Building located a several hundred feet southwest of the subject SR-4 bridges over Walnut Creek. (The site is labeled with the number “1741” on the attached Plate 3.) ENGEO’s study included geophysical profiling and trenches which showed that the main trace of the Concord fault does not pass through that site and is probably located beneath the Walnut Creek channel east of that site.

Peter Kaldveer and Associates (1983) AP-1562

Peter Kaldveer and Associates (1984) conducted a fault investigation of a large site located north of SR-4 and east of Solano Way. (The site is labeled with the number “1562” on the attached Plate 3.) The trenches crossed the mapped eastern trace of the Concord fault (derived from Sims, et al; 1973) and found no evidence for past faulting. Subsequently, Wills and Hart (1992) recommended that the eastern trace and the Special Studies Zone associated with it be eliminated. That fault trace and zone were not included on the 1993 release of the revised maps.

Peter Kaldveer and Associates (1984) AP -1712

Peter Kaldveer and Associates (1984) conducted a fault investigation of the seven acre site located immediately east of Walnut Creek, north of SR-4 and south of then Arnold Industrial Way (now Imhoff Dive). (The site is labeled with the number “1712” on the attached Plate 3.) The investigation included borings as well as magnetometer and resistivity surveys. Based upon the indications of different depths to groundwater and bedrock, PKA concluded that the Concord fault does not pass through that site and is located west of that site beneath the Walnut Creek channel.

Woodward-Clyde Consultants (1985) AP-1809

Woodward-Clyde Consultants (1985) conducted an investigation of a site located approximately 150 feet southeast of the SR-4 bridges. (The site is labeled with the number “1809” on the attached Plate 3.) They concluded that the Concord fault does not pass through that site and is located beneath the Walnut Creek channel.

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Rogers/Pacific (1988) AP-3062

Deep borings and gravity data were used by Rogers/Pacific (1988) to infer the location of the Main Trace of the Concord fault within a zone several hundred feet wide trending northwest across the eastern portion of a large parcel located approximately 8,000 feet northwest of the subject SR-4 bridges. (The site is labeled with the number “3062” on the attached Plate 3.)

Darwin Meyers Associates (1990) AP-2438

Darwin Meyers Associates (1990) conducted a fault investigation of the 6.9 acre parcel (100 feet wide and 3000 feet long) that was the former Southern Pacific Railroad right-of-way located immediately east of Solano Way (approximately 1200 feet east of the subject SR-4 bridges). (The site is labeled with the number “2438” on the attached Plate 3.)

Wills and Hart (1992)

Wills and Hart (1992) prepared a Fault Evaluation Report for the Concord fault (FER-231) in conjunction with the California Division of Mines and Geology’s re-evaluation of the State Special Studies Zones established along the Concord Fault in 1974. The report includes summaries of published maps and consulting geologists’ reports of site-specific studies.

Based on the trench log of Peter Kaldveer Associates (1983; AP1562) that showed no evidence of faulting, Wills and Hart recommended the previously zoned eastern trace (located approximately 3100 feet east of the Main Trace of the fault trace) and its zone be eliminated. In addition, they recommended a “new” East Trace be added along the eastern flank of Tank Farm Hill (crossing SR-4 approximately 720 feet east of the Main Trace) where they noted the existence of a “broad scarp, side-hill bench and tonal” and “disrupted bedding in older alluvium, Locality 12.”

Where Waterfront Road crosses Pacheco Creek, Wills and Hart noted “Locality 10 – right-lateral deflection of Waterfront Road Bridge field checked.” Where the Santa Fe Railroad crosses the western edge of the creek channel, they noted “Locality 11 – right-lateral deflection of railroad near west end of bridge field checked.” Where the Imhoff Drive Bridge (“Locality 2a”), Wills and Hart noted “Caltrans borings, difference in elevation of bedrock – alluvium contact up to east”. Where the new bridges cross Walnut Creek (“Locality 2b”), Wills and Hart noted ““gouge” in boring” (reference to the Caltrans Log of Boring B-12 located approximately 100 feet east of the west ends of the bridges). Also noted by Wills and Hart were the apparent difference in “depth to water table” (5 to 7 feet east of the fault and 13 to 15 feet west of the fault) on opposite sides of the mapped Main Trace of the Concord fault reported in ENGEO’s (1977) site-specific investigation report (AP1741). Where the original SR-4 bridge (built in 1938) crosses Walnut Creek, Wills and Hart noted “right-lateral deflection ? of bridge field checked 12/18/91”. In the area of Stanwell Drive (5200 feet southeast of SR-4), they noted “Locality 13 – right-lateral deflected curb.”

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Wills and Hart (1992) summarized the findings reported by Rogers/Pacific (1988) in their report of their investigation of a site located approximately 8000 feet northwest of the subject SR-4 bridges. Both gravity data and deep borings were used by Rogers/Pacific to conclude that the main trace of the Concord fault is located within a 200-foot wide zone beneath Pacheco Creek.

Wills and Hart (1992) summarized the findings of many other site-specific investigations conducted on other sites within the central business district of downtown Concord where several traces of the Concord fault where exposed in trenches and surface evidence of creep deformation has been observed along the previously mapped fault.

Galehouse and Lienkaemper (2003)

The results of several decades of surveys conducted on alignment arrays that extend across several faults in the San Francisco Bay Region were reported by Galehouse and Lienkaemper (2003). Two arrays that cross the Concord fault in the downtown area (about 2 miles southeast of the SR-4 bridges) indicated right-lateral creep had been continuing at a rate of 2.5 to 3.5 millimeters per year.

Bryant, Sander, and Wills (2007)

The Digital Database for the Concord and Green Valley faults (Final Technical Report) was produced by Bryant, et al (2007) for the U. S. Geological Survey’s National Earthquake Hazards Reduction Program. Based upon all available data, Bryant, et al compiled mapped fault traces which were used to update the digital files for use in Google Earth.

Johansson, et al (2009)

Using permanent scattered interferometric synthetic aperture radar (PS-InSAR) data, Johanson and others (2009) calculated right-lateral creep was occurring at a rate of 2.8 to 3.7 mm/yr along the Concord fault.

MacFarland, et al (2009 – 2014)

MacFarland and others have continued the surveys of alignment arrays begun be Galehouse and others in 1979. The latest update confirms the long-term creep rate measured at two locations on the Concord fault is 2.9 to 3.6 mm/yr.

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TOPOGRAPHY, AIR-PHOTOS AND SITE RECONNAISSANCE

Topographic Maps and Air-Photos

We evaluated the 7.5’ topographic maps and stereo-pair air photos of the Concord fault in the area (Plate 1) to assess the geomorphic evidence for the location of the Concord fault.

There is a distinctive and characteristic linear west-facing escarpment along the west side of Tank Farm Hill north of SR-4. (See Plate No. 2.) South of SR-4, there are several topographic highs located east of the mapped Main Trace of the fault. However, at the location of the SR-4 bridges themselves, there is essentially no topographic indication of past fault movement visible at the ground surface. However, the data from the borings conducted prior to design and construction of the SR-4 bridges and the Imhoff Bridge do show an indication of a topographic step buried beneath the young alluvial deposits that suggests the Main Trace of the Concord fault is located beneath the man-made channel of Walnut Creek.

Most of the air-photos we reviewed did not provide a view of the ground surface unaffected by human activities as development of the area began early in the 20th century. Only the 1939 air- photos provide a view of the area before the Walnut Creek Channel was modified by humans; however, the original SR-4 bridge (now known as the Marsh Road Bridge) had already been constructed. There are several tonal lineaments (which were noted by Wills and Hart; 1992) running just west of the west-facing escarpment along the west side of Tank Farm Hill in the area that was subsequently graded to produce what is now the linear channel of Walnut Creek. However, there are no clear indications of the surface trace of the Concord fault visible in the air- photos.

Site Reconnaissance

We visited the site on February 17, 2014. We examined the bridges and adjacent surfaces for evidence of fault movement. Although we observed and photographed many fine cracks in the concrete elements of the SR-4 bridges, we did not find any displacements that we could confidently attribute to fault creep. However, there at indications of possible fault-related rotation of the Marsh Road Bridge (built in 1938) in the apparent differences in widths of its expansion joints.

Conclusions from Literature Review and Site Visit

The Concord fault is active (capable of producing a 6.6M earthquake) with a long-term slip rate of 4.3 mm/year. The Main Trace of the fault is located beneath the SR-4 bridges that cross over Walnut Creek. Creep has been occurring at a rate of 2.5 to 3.5 mm/year along the fault south of the bridges during the past 5 decades; however, there are not clear indications of such ground deformation manifested in the bridges themselves. The extent to which the mapped East Trace of the fault may rupture along with the Main Trace is not known; therefore, in order to be

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conservative, we assume that all of the anticipated surface displacement will occur along the Main Trace of the fault that passes beneath the bridges footprints. The most likely location of the Main Trace beneath the bridges is approximately 100 feet east of their western abutments.

CALCULATIONS OF EXPECTED FAULT RUPTURE DISPLACEMENT

To quantify potential fault displacement, we used a spreadsheet developed by the Division of Research and Innovation in collaboration with Geotechnical Services based upon methods presented in Petersen, et al. (2011), and Abrahamson (2008). Both a deterministic fault displacement analysis and a probabilistic fault displacement analysis were performed. The input parameters included the following:

Maximum Moment Magnitude (Mmax)

The Mmax of 6.6 is taken from the 2012 Caltrans Fault Database V2b. After applying the aseismicity of 0.5, Mmax reduced to 6.3 in the spreadsheet.

Slip Rate

Dawson and Weldon (2012) use 4.3 mm/year as the UCERF3 best estimate for slip rate.

Empirical Slip Measurements

We found no published paleoseismic measurements of displacements that have occurred along the northern Concord fault to constrain fault movements. There are no published accounts of past surface ruptures. Therefore, we did not include any empirical slip measurements in the worksheet used to calculate anticipated surface rupture displacement values at the bridges.

Site-to-Source Distance

The Alquist-Priolo Earthquake Fault Zone Maps (CDMG; 1993a&b) show the Walnut Creek bridges straddle the mapped Main Trace of the Concord fault. Based on the descriptions of materials recovered from borings drilled by Caltrans prior to bridge construction (Logs of Test Borings, 1974), it appears that the Main Trace is located approximately 100 feet (30 meters) east of the western abutments of the Walnut Creek Bridges. The Log of Boring B-10 (at Station 240+50) describes “Brown CLAYSTONE with SLICKENSIDES, vertical structure” in the sample taken at a depth of 65 feet. The Log of Boring B-12 (at Station 233+78) describes “Gray, fractures, SANDSTONE in dark gray matrix of CLAY gouge” and Gray, very fine,-grain Sandstone with SHALE seams (vertical bedding). However, the Main Trace of the Concord fault may pass beneath the bridges anywhere within the bridges footprints at essentially a right angle. The azimuth of the bridges is 64 degrees (N64ºE) and the azimuth of the fault is 333 degrees (N27ºW).

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The East Trace of the Concord Fault is mapped 886 feet (270 meters) east of the Main Trace.

Type of Slip

The Main Trace of the Concord fault is a right-lateral strike-slip fault with some normal (vertical) component. Therefore, we anticipate that the ground located west of the fault will move northwestward and down relative to the ground located east of the fault.

Relative Slip of Multi-strand Faults

In order to be conservative, the percentage contribution to the total fault displacement that will occur along the Main Trace and East Trace of the Concord fault was assumed to be 100% and 0%, respectively. (We assume that all of the calculated displacement will occur along the Main Trace.)

CALCULATED POTENTIAL FAULT RUPTURE DISPLACEMENT

Fault Displacement (Horizontal)

The deterministic and probabilistic fault rupture displacements were calculated using the Caltrans “Strike-Slip Offset” Worksheet (2013c). Graphs showing the spatial distribution of the resultant deterministic and probabilistic off-fault displacements are presented in Plates 4A and 4B, respectively. The input parameters and the calculated maximum displacement within the Walnut Creek Bridges are presented in the following table:

Table 1 - Results of Displacement Calculations 1 Model Mmax Slip Rate Aseismicity Site-to-Source Deterministic Probabilistic (mm/yr) Factor Distance2 Displacement (5% in 50 yrs) Displacement

Main 0.22 meters 0.57 meters 6.6 4.3 0.5 0 m Trace (8.7 inches)2 (22.4 inches)2 1Caltrans Fault Database v2b (2012) 2At a point directly on the Main Trace within the bridge footprint.

Vertical Displacement

Vertical displacements of approximately 10% of the horizontal offset should be assumed to occur along with horizontal displacement. This corresponds to vertical displacements of approximately 0.02 m (0.9 inch) for the deterministic case and 0.06 m (2.7 inches) for the probabilistic case.

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Respectfully Submitted, PARIKH CONSULTANTS, INC.

Emre Ortakci, P.E. 76040 James B. Baker, C.E.G. 1021 Project Engineer Engineering Geologist

Alston Lam, P.E., G.E. 2605 Gary Parikh, P.E., G.E., 666 Senior Project Engineer Project Manager

12-31-15

Attachments: List of Published References List of Site-Specific Investigation Reports Plate No. 1 – Location Map Plate No. 2 – State Earthquake Fault Zone Map Plate No. 3 – Alquist-Priolo Fault Investigation Sites Map Plate No. 4A – Deterministic Fault Rupture Plate No. 4B – Probabilistic Fault Rupture

S:\Ongoing\Alston Lam\2013-105-Hwy 4 Bridges\Fault Rupture Hazard Report\revised_concord fault displacement_WC_04292014.docx

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LIST OF PUBLISHED REFERENCES

Abrahamson, N., 2008, Appendix C, Probabilistic Fault Rupture Hazard Analysis, San Francisco Public Utilities Commission, General Seismic Requirements for the Design on New Facilities and Upgrade of Existing Facilities

Bryant, W.A., Sander, E.F., and Wills, C.J., 2007, Digital Database for the Concord and Green Valley faults, Final Technical Report, U.S. Geological Survey National Earthquake Hazards Reduction Program (NHERP), Project Award Number 05HQGR0029.

California Division of Mines and Geology, 1974a, State of California Special Studies Zones, Vine Hill quadrangle: California Division of Mines and Geology, scale of 1:24,000.

California Division of Mines and Geology, 1974b, State of California Special Studies Zones, Walnut Creek quadrangle: California Division of Mines and Geology, scale of 1:24,000.

California Division of Mines and Geology, 1993a, State of California Special Studies Zones, Revised Official Map, Vine Hill Quadrangle, California Division of Mines and Geology, scale 1:24,000.

California Division of Mines and Geology, 1993b, State of California Special Studies Zones, Revised Official Map, Walnut Creek Quadrangle, California Division of Mines and Geology, scale 1:24,000.

California Geological Survey, 2002, Guidelines for evaluating hazard of surface fault rupture, CGS Note 49, 4p: http://www.conservation.ca.gov/cgs/information/publications/cgs_notes/note_49/Docume nts/note_49.pdf

California Geological Survey, 2010, An Explanatory Text to Accompany the Fault Activity Map of California, Scale 1:750,000 http://www.conservation.ca.gov/cgs/cgs_history/Documents/FAM_phamplet.pdf

Caltrans, 2012, Fault Database v2b, http://dap3.dot.ca.gov/ARS_Online/technical.php

Caltrans, 2013a, Memo to Designers 20-10, Fault Rupture: http://onramp.dot.ca.gov/hq/esc/sd/bridge_design/gec/documents/MTDS20- 10%209%2024%2012.pdf

Caltrans, 2013b, Memo to Designers 20-8, Analysis of Bridges that Cross Faults, http://www.dot.ca.gov/hq/esc/techpubs/manual/bridgemanuals/bridge-memo-todesigner/ page/Section%2020/20-8.pdf Caltrans, 2013c, “Strike-Slip Offset” Worksheet, http://www.dot.ca.gov/hq/esc/geotech/geo_support/geo_instrumentation/fault_rupture/

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Dawson, T., and Weldon, R., 2012, UCERF3 Appendix B: Geologic Slip Rate Data and Geologic Deformation Model (Nov. 5, 2013). http://wgcep.org/sites/wgcep.org/files/AppendixB_GeologicDeformationModel_2012070 9.pdf

Galehouse, J.S., and Lienkaemper, J.J., 2003, Inferences Drawn from Two Decades of Alignment Array Measurements of Creep on Faults in the San Francisco Bay Region, Bulletin of the Seismological Survey of America (BSSA), vol. 93, no. 6, pp. 2415-2433.

Graymer, R.W., Bryant, W.A., McCabe, C.A., Hecker, S., and Prentice, C.S., 2006, Map of Quaternary-active faults in the San Francisco Bay region: U.S. Geological Survey Scientific Investigations Map 2919.

Johansson, I., Burgmann, R., Ferretti, A., and Novadi, F., 2009, Creep Measurements on the Concord Fault from PS-InSAR, Berkeley Seismological Laboratory, Annual Report 2008-2009.

Hecker, S., Abrahamson, N.A., and Wooddell, K.E., 2013, Variability of Displacement at a Point: Implications for Earthquake Size Distribution and Rupture Hazard on Faults Bulletin of the Seismological Society of America April 2013 vol. 103 no. 2A 651-674.

MacFarland, F.S., Lienkaemper, J.J., and Caskey, S.J., 2009 rev. 2014, Data from Theodolite Measurements of Creep Rates on San Francisco Bay Region Faults, California, U.S. Geological Survey Open File OF2009-1119v.1.5.

Petersen, M.D., Dawson, T.E., Chen, R., Cao, T., Wills, C.J., Schwartz, D.P, and Frankel, A.D., 2011, Fault Displacement Hazard for Strike-slip Faults, Bulletin of the Seismological Society of America, vol. 101, no. 2, p 805-825.

Poland, J.F., 1935, Ground-water conditions in Ygnacio Valley, California: Stanford University, unpublished M.A. thesis, 83 p.

Sharp, R.V., 1973, Map showing recent tectonic movement on the Concord fault, Contra Costa and Solano Counties, California: U.S. Geological Survey Miscellaneous Field Studies Map MF- 505, SFBRS Basic Data Contribution 55, map scale 1:24,000.

Sims, J.D., Fox, K.F., Jr., Bartow, J.A., and Helley, E.J., 1973, Preliminary geologic map of Solano County and parts of Napa, Contra Costa, Marin, and Yolo counties, California: U.S. Geological Survey Miscellaneous Field Studies Map MF-484 (also SFBRS Basic Data Contribution 54), map scale 1:62,500.

Snyder, D.L., Wills, C.J., and Borchardt, G.A., 1995, Slip rate and earthquake recurrence on the Concord fault at Galindo Creek, California: U.S. Geological Survey, Final Technical Report, National Earthquake Hazards Reduction Program, Contract No. 1434-94-G-2483, 37 p.

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US Geological Survey, 2010, Quaternary Faults in Google Earth: http://earthquake.usgs.gov/hazards/qfaults/google.php

US Geological Survey, 2008, National Seismic Hazard Maps – Fault Parameters, http://geohazards.usgs.gov/cfusion/hazfaults_search/hf_search_main.cfm

Wells, D., and Coppersmith, K., 1994, New Empirical Relationships Among Magnitude, Rupture Length, Rupture Width, Rupture Area, and Surface Displacement, Bulletin of the Seismological Society of America, vol. 84, No. 4, p. 974-1002.

Wills, C.J., and Hart, E.W., 1992a, Progress in understanding the Concord fault through site specific studies, in Borchardt, G., and others, (editors), Proceedings of the Second Conference on Earthquake Hazards in the Eastern San Francisco Bay Area: California Division of Mines and Geology Special Publication 113, p. 311-317.

Wills, C.J., and Hart, E.W., 1992b, The Concord fault, Contra Costa County, California, Division of Mines and Geology Fault Evaluation Report FER-231, 37 p., map scale 1:24,000, in Fault Evaluation Reports Prepared Under the Alquist-Priolo Earthquake Fault Zoning Act, Region 1 – Central California: California Geological Survey CGS CD 2002-01 (2002).

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LIST OF SITE-SPECIFIC INVESTIGATION REPORTS

[The following reports are included in Fault Investigation Reports for Development Sites within Alquist-Priolo Earthquake Fault Zones in Northern California, 1974-2000: California Geological Survey CGS CD 2003-01 (2003).]

Burkland and Associates, 1973a (6-8), Geologic and Seismic Hazard Investigation, Cyclotron Corporation Site, Buchanan Oaks Office and Industrial Park, Concord California, consultant’s report, (CGS file no. AP-0001.1).

Burkland and Associates, 1973b (6-11), Geologic and Seismic Hazard Investigation, Buchanan Oaks Office and Industrial Park, Concord California, consultant’s report prepared for Duffel Financial & Construction, (CGS file no. AP-0001.2).

Burkland and Associates, 1974a (7-19), (Trench Logs) Parcels 7 through 16, Buchanan Oaks, Concord California, consultant’s report prepared, (CGS file no. AP-0001.3).

Burkland and Associates, 1974b (12-13), Geologic and Seismic Hazards Investigation, I. Deutscher Co. Warehouse, Concord California, (CGS file no. AP-0062).

Burkland and Associates, 1976 (11-22), Supplemental Geotechnical Investigation, Cyclotron Property (Stanwell Drive), Buchanan Oaks Industrial Park, Concord California, consultant’s report, (CGS file no. AP-0001.4).

Darwin Meyers Associates, 1990 (6-20), Fault Hazard Reconnaissance, South East Quadrant SR- 4 / Walnut Creek Channel, Concord, California, consultant’s report, (CGS file no. AP-2438).

ENGEO Incorporated, 1977a (7-19), Alquist-Priolo Seismic Hazard Study, Proposed Kiewit Office Building, Concord California, consultant’s report, (CGS file no. AP-1741).

ENGEO Incorporated, 1977 (8-18), Geologic Trenches and Concord Fault, Buchanan Oaks Eight, Stanwell Drive, Concord California, consultant’s report, (CGS file no. AP-0001.5).

Harding Lawson Associates, 1982a (2-19), Soil Investigation, Central Bank Office Complex, Stanwell Drive, Concord, California, (Plate 1 is dated 2-4-1982), consultant’s report, (CGS file no. AP-0001.8).

Harding Lawson Associates, 1982b (5-7), Consultation (Fault Trace), Central Bank Office Complex, Stanwell Drive, Concord, California, (Plate 1 is dated 1982-2-1), consultant’s report, (CGS file no. AP-0001.8).

Peter Kaldveer and Associates, 1983 (8-23), Fault Location Study, Proposed Concord North Industrial Study, Concord, California, consultant’s report, (CGS file no. AP-1562).

WMH Corporation I-680/SR-4 Interchange Project - Phase 3 (SR-4 Widening) Project No: 2013-105-WCB April 29, 2014 Attachment Page 5

Peter Kaldveer and Associates, 1984 (4-25), Feasibility Foundation Investigation and Fault Location Study, Seven-Acre Industrial Park, Contra Costa County, California, consultant’s report, (CGS file no. AP-1712).

Rogers Pacific, 1988, Status report, fault investigation, IT Baker Site, Vine Hill treatment complex, Martinez area, Contra Costa County, unpublished consultant’s report, 55 p. (CGS file no. AP-3062).

Woodward-Clyde Consultants, 1979a (7-27), Phase I Alquist-Priolo Study, 2550 Stanwell Drive, Concord, California, consultant’s report prepared for Deluxe Check Printers, (CGS file no. AP- 0001.6).

Woodward-Clyde Consultants, 1979b (10-31), Phase II Alquist-Priolo Study, Deluxe Check Printers Building, 2550 Stanwell Drive, Concord, California, consultant’s report (CGS file no. AP-0001.7).

Woodward-Clyde Consultants, 1985 (6-24), Phase I Alquist-Priolo Geologic Study of Proposed Magnussen Dodge Dealership at the Corner of Marsh Road and Solano Way, Concord, California, consultant’s report (CGS file no. AP-1809).

Walnut Creek Bridges

0 Scale: 2000 ft Source: Google Maps 2014 LOCATION MAP I-680/SR-4 INTERCHANGE PROJECT - PHASE 3 (SR 4 WIDENING) WALNUT CREEK BRIDGE (MEDIAN WIDENING) CONTRA COSTA COUNTY, CALIFORNIA JOB NO.: 2013-105-WCB PLATE NO.: 1 Concord Fault (East Trace)

Concord Fault (Main Trace)

Source: California Division of Mines and Geology; 1993a&b; Special Studies Zones Maps; Walnut Creek and Vine Hill Quadrangles

Walnut Creek Bridges

0 Scale: 2000 ft STATE EARTHQUAKE FAULT ZONE MAP I-680/SR-4 INTERCHANGE PROJECT - PHASE 3 (SR 4 WIDENING) WALNUT CREEK BRIDGE (MEDIAN WIDENING) CONTRA COSTA COUNTY, CALIFORNIA JOB NO.: 2013-105-WCB PLATE NO.: 2 3062

1562

Source: CGS CD 2003‐01‐Fault Investigation Reports for Development Sites within Alquist‐Priolo Earthquake Fault Zones In North California, 1974‐2000 1712

Note: Numbers refer to the CGS file 1741 numbers included in the text and list of 1809 references. 2438 0062

Walnut Creek Bridges

0001

ALQUIST-PRIOLO FAULT INVESTIGATION SITES MAP I-680/SR-4 INTERCHANGE PROJECT - PHASE 3 (SR 4 WIDENING) WALNUT CREEK BRIDGE (MEDIAN WIDENING) CONTRA COSTA COUNTY, CALIFORNIA JOB NO.: 2013-105-WCB PLATE NO.: 3 0.25

0.2

Main Trace 0.15 East Trace

Combined 0.1 Fault Displacement (m) Displacement Fault

0.05

Walnut Creek Bridge 0 -200 -150 -100 -50 0 50 100 150 200

Distance from Main Fault Trace (m)

Graph showing deterministic offset. Offset at the bridge (between x = -30 through x = +100 ) could be up to 0.22 meters with 100% probability of rupture on the Main Trace of the fault within bridge footprint. No weight on East Trace 270 m from the Main Trace

DETERMINISTIC FAULT RUPTURE

I-680/SR-4 INTERCHANGE PROJECT - PHASE 3 (SR 4 WIDENING) PARIKH CONSULTANTS, INC. WALNUT CREEK BRIDGE (MEDIAN WIDENING) GEOTECHNICAL CONSULTANTS CONTRA COSTA COUNTY, CALIFORNIA MATERIALS TESTING JOB NO.: 2013-105-WCB PLATE NO.: 4A 0.6

0.5

0.4 Main Trace

East Trace 0.3 Combined

0.2 Fault Displacement (m) Displacement Fault

0.1 Walnut Creek WalnutBridge Creek Limits Bridge 0 -200 -150 -100 -50 0 50 100 150 200

Distance from Main Fault Trace (m)

Graph showing probabilistic offset. Offset at the bridge (between x = -30 through x = +100 ) could be up to 0.57 meters with 100% probability of rupture on the Main Trace of the fault within bridge footprint. No weight on East Trace 270 m from the Main Trace

PROBABILISTIC FAULT RUPTURE

I-680/SR-4 INTERCHANGE PROJECT - PHASE 3 (SR 4 WIDENING) PARIKH CONSULTANTS, INC. WALNUT CREEK BRIDGE (MEDIAN WIDENING) GEOTECHNICAL CONSULTANTS CONTRA COSTA COUNTY, CALIFORNIA MATERIALS TESTING JOB NO.: 2013-105-WCB PLATE NO.: 4B