APPENDIX D. Initial Study Geology and Soils

Transcription

1 APPENDIX D Initial Study Geology and Soils

2 Type of Services Project Name Initial Study Geology and Soils 4th Avenue and Railroad Avenue Mixed Use Location Client 4th Avenue and Railroad Avenue San Mateo, California Windy Hill Property Ventures Client Address 530 Emerson Street, Suite 150 Palo Alto, California Project Number Date July 1, 2016 Prepared by Nick Zoetewey, P.E. Project Engineer Geotechnical Project Manager C. Barry Butler, P.E., G.E. Senior Principal Engineer Quality Assurance Reviewer

3 Table of Contents SECTION 1: INTRODUCTION Project Description Scope of Services SECTION 2: REGIONAL SETTING Geologic Setting Regional Seismicity Table 1: Approximate Fault Distances within 25-Kilometers... 4 SECTION 3: SITE CONDITIONS Geomorphology and Recent History Site Reconnaissance and Surface Description Soils Ground Water SECTION 4: GEOLOGIC HAZARDS Fault Rupture Strong Ground Shaking Liquefaction Potential Lateral Spreading Ground Rupture Seismically Induced Settlement Expansive Soils Existing Fills Landsliding Page i

4 4.10 Seismically Induced Waves Flooding SECTION 5: PRELIMINARY CONCLUSIONS Preliminary Impacts Strong Ground Shaking Potential for Liquefaction Induced Settlements High Ground Water Dewatering Proximity of Basement Excavation to Adjacent Improvements Presence of Undocumented Fill Potential for Presence of Expansive Soils Feasible Foundations Final Design-Level Geotechnical Report SECTION 6: CLOSURE AND LIMITATIONS SECTION 7: REFERENCES FIGURE 1: FIGURE 2: FIGURE 3: FIGURE 4: VICINITY MAP SITE PLAN REGIONAL FAULT MAP VICINITY GEOLOGIC MAP Page ii

5 Type of Services Project Name Location Initial Study Geology and Soils 4th Avenue and Railroad Avenue Mixed Use San Mateo, California SECTION 1: INTRODUCTION This report has been prepared for the proposed future development at the above referenced property. The location of the site is shown on the Vicinity Map, Figure 1. For our use, we were provided with the following documents: An architectural plan set, titled A Planning Application for: Windy Hill Property Ventures, 4 th Avenue & Railroad Avenue, San Mateo, CA 94401, prepared by ArcTec, dated March 15, A previous Phase I environmental report at the site, titled Phase I Environmental Site Assessment, 405 East 4 th Avenue and 330 South Claremont Street, San Mateo, California, prepared by PES Environmental, dated 14, This report included the data and reports from several previous investigations at the site. 1.1 PROJECT DESCRIPTION The project site is located north of E. 4th Avenue between S. Railroad Avenue and S. Claremont Avenue in San Mateo, California. We have discussed the site with you, reviewed relatively recent aerial photographs of the site, visited the site, and reviewed the plans provided. The site is currently occupied by two one-story buildings and associated parking and landscape areas. We understand that the existing buildings will be demolished and that a new building will be constructed that will consist of four stories of above-grade commercial and residential space over two levels of below-grade parking. The planned development will have a footprint of approximately 18,368 square feet, which will occupy most of the approximately ½-acre site. Appurtenant utilities, landscaping and other improvements necessary for site development are also planned. The site is bounded by an existing commercial building and parking lot to the northwest, S. Railroad Avenue to the southwest, Railroad Avenue to southeast, and S. Claremont Street to the northeast. Page 1

6 1.2 SCOPE OF SERVICES Our scope of services was presented in our agreement dated May 23, 2016, and includes geologic research and consolidation of data, site reconnaissance, identification of potential geologic, seismic and geotechnical impacts, a discussion of potential mitigation measures, drafting and report preparation. SECTION 2: REGIONAL SETTING 2.1 GEOLOGIC SETTING Regional Geologic Setting The relatively flat-lying plain along the western edge of the San Francisco Bay is bounded by the Santa Cruz Mountains on the west and the San Francisco Bay to the east. The Coast Ranges is a geomorphic province of California that stretches from the Oregon border nearly to Point Conception. In the San Francisco Bay area, most of the Coast Ranges have developed on a basement of tectonically mixed Cretaceous- and Jurassic-age (70- to 200-million years old) rocks of the Franciscan Complex. Younger sedimentary and volcanic units locally cap these basement rocks. Still younger surficial deposits that reflect geologic conditions of the last million years or so cover most of the Coast Ranges. Movement on the many splays of the San Andreas Fault system has produced the dominant northwest-oriented structural and topographic trend seen throughout the Coast Ranges today. This trend reflects the boundary between two of the Earth's major tectonic plates: the North American plate to the east and the Pacific plate to the west. The San Andreas Fault system and its major branching faults is about 40 miles wide in the Bay area and extends from the San Gregorio Fault near the coastline to the Coast Ranges-Central Valley blind thrust at the western edge of the Great Central Valley as shown on the Regional Fault Map, Figure 3. The San Andreas Fault is the dominant structure in the system, nearly spanning the length of California, and capable of producing the highest magnitude earthquakes. Many other subparallel or branch faults within the San Andreas system are equally active and nearly as capable of generating large earthquakes. Right-lateral movement dominates on these faults but an increasingly large amount of thrust faulting resulting from compression across the system is now being identified also Local Geology Roughly half the San Mateo 7.5 minute Quadrangle and adjacent areas is covered by Quaternary alluvial sediment shed from the northwest-trending Santa Cruz Mountains that occupy the area west of the site (Pampeyan, 1994). The site is in an area adjacent to the San Francisco Bay where Holocene age (11,000 years or less before present) alluvial fan deposits account for the majority of Quaternary sediment deposited in the area. The Regional Scale published map of Pampeyan (1994) is provided on Figure 4, Vicinity Geologic Map. The site is shown as underlain by medium-grained alluvium (Qam) of Holocene age over older alluvium (Qoa) of Pleistocene age. Page 2

7 The Qam unit is described as unconsolidated to moderately consolidated, moderately sorted fine sand, silt and clayey silt. The Qam unit is generally less than 20 feet thick, was deposited at the edge of coarse-grained alluviual fans (Qac) and locally interfingers with coarse and finegrained alluvium (Qaf). It forms much of the flatland alluvial plain along the western edge of the Bay in the Palo Alto quadrangle. The Qoa unit is designated as (Late Pleistocene) older alluvial fan deposits and is described as; unconsolidated to moderately consolidated gravel, sand and silt. Franciscan Complex bedrock underlies the site at depth. This was encountered at Elevation -323 feet (about 347 feet below existing grades) in a boring shown by Pampeyan (1994) to be located about 0.3 miles east of the subject site (see Figure 4). 2.2 REGIONAL SEISMICITY The San Francisco Bay area region is one of the most seismically active areas in the Country. While seismologists cannot predict earthquake events, the U.S. Geological Survey s Working Group on California Earthquake Probabilities 2015 revised earlier estimates from their 2008 (2008, UCERF2) publication. Compared to the previous assessment issued in 2008, the estimated rate of earthquakes around magnitude 6.7 (the size of the destructive 1994 Northridge earthquake) has decreased by about 30 percent. The expected frequency of such events statewide has dropped from an average of one per 4.8 years to about one per 6.3 years. However, in the new study, the estimate for the likelihood that California will experience a magnitude 8 or larger earthquake in the next 30 years has increased from about 4.7% for UCERF2 to about 7.0% for UCERF3. UCERF3 estimates that each region of California will experience a magnitude 6.7 or larger earthquake in the next 30 years. Additionally, there is a 63 percent chance of at least one magnitude 6.7 or greater earthquake occurring in the Bay Area region between 2007 and During such an earthquake the danger of fault surface rupture at the site is slight, but very strong ground shaking would occur. Although earthquakes can cause damage at a considerable distance, shaking will be very intense near the fault rupture. Therefore, earthquakes centered in urbanized areas of the region have the potential to cause much more damage than the 1989 Loma Prieta earthquake. Faults considered capable of generating significant earthquakes are generally associated with the well-defined areas of crustal movement, which trend northwesterly. Table 1 presents the State-considered active faults within a 25-kilometer (about 15 mile) radius of the project. Local faults are indicated on the Regional Fault Map, Figure 3, illustrating the distances of the site to significant fault zones. Page 3

8 Table 1: Approximate Fault Distances within 25-Kilometers Fault Name Distance (miles) Distance (kilometers) San Andreas San Gregorio Hayward (Total Length) SECTION 3: SITE CONDITIONS 3.1 GEOMORPHOLOGY AND RECENT HISTORY The site is located in an area that is nearly level and has not received substantial grading (other than the fills encountered from removal of an underground storage tank (see PES environmental report for information and location). Aerial photographs listed in the References section show the site vicinity at five different times spanning the period from 1943 to 1990 and additional photos were reviewed through Google Earth that show the site and vicinity from 1991 through As of 1943 the site and adjacent areas were already extensively developed for commercial, light industrial and residential. Throughout the succeeding decades little has changed. The subsequent photos for the 2000 s show virtually no changes in the site. 3.2 SITE RECONNAISSANCE AND SURFACE DESCRIPTION A reconnaissance of the site was performed by our field engineer. The site consists of two parcels: the northeast parcel is located at 403 East 4 th Avenue and the southwest parcel is located at 330 South Claremont Street. The site at both parcels is relatively flat and is generally level with current city streets and sidewalks. The northeast property is occupied by a commercial building, consisting of an automotive repair shop. Based on our observations, the building is in fair condition and significant distress was not observed. The existing pavement consists of asphalt concrete (AC) and Portland cement concrete (PCC) and was observed to be in fair condition with some minor cracking. Overall, the northeast property looks to be well maintained. The southwest property is occupied by an abandoned commercial building and a PCC paved parking lot located at the front of the property. Distress to the exterior of the existing building consisted of cracks on side walls and rusting on the window panels and on the garage door. Significant transverse cracking with minor alligator cracks were observed in the PCC parking lot. Grass and weeds were observed in the cracks of the concrete pavement. We anticipate minor fills will be located below the existing buildings. 3.3 SOILS As noted above, several environmental investigations have occurred at the site. A portion of the site is underlain by up to 6½ feet of fill that consisted of silty clay with gravel or aggregate base Page 4

9 with concrete rubble (likely where an underground storage tank (UST) was removed, as described in the PES Environmental report, see location in report), or by native silty soils that were generally encountered over the remainder of the site. The fills or native surficial soils were underlain by alternating layers of sandy silt and silty sand with intermittent layers of silty clay, which were encountered to the maximum depths explored of up to approximately 32 feet. 3.4 GROUND WATER Ground water data at the site ranged from about 16½ to 21 feet below existing grades at the time the readings were taken. The State of California has not yet mapped historic high ground water in the area; however, based on data from nearby investigations and the data above, ground water is anticipated to be at depths ranging from about 15 to 22 feet below existing site grades. Fluctuations in ground water levels occur due to many factors including seasonal fluctuation, underground drainage patterns, seasonal recharge, regional and tidal fluctuations, and other factors. SECTION 4: GEOLOGIC HAZARDS This section presents our review and comments concerning potential geologic hazards affecting the proposed project. 4.1 FAULT RUPTURE As discussed above several significant faults are located within 25 kilometers of the site. The site is not located within a State-designated Alquist Priolo Earthquake Fault Zone. As shown in Figure 4, no known surface expression of fault traces is thought to cross the site; therefore, fault rupture hazard is not a significant geologic hazard at the site. 4.2 STRONG GROUND SHAKING Moderate to severe (design-level) earthquakes can cause strong ground shaking, which is the case for most sites within the Bay Area. While a seismic hazard analysis was not prepared as part of the preparation of this report, strong ground shaking should be expected at the site during the life of the planned structure. 4.3 LIQUEFACTION POTENTIAL The State of California is in the process of mapping seismic hazards statewide. These maps will assist cities and counties in fulfilling their responsibilities for protecting the public safety from the effects of earthquake-triggered ground failure as required by the Seismic Hazards Mapping Act. The site is not currently mapped by the state; however, the site is mapped by the Association of Bay Area Governments (ABAG) as being in an area of low liquefaction potential. Page 5

10 During strong seismic shaking, cyclically induced stresses can cause increased pore pressures within the soil matrix that can result in liquefaction triggering, soil softening due to shear stress loss, potentially significant ground deformation due to settlement within sandy liquefiable layers as pore pressures dissipate, and/or flow failures in sloping ground or where open faces are present (lateral spreading) (NCEER 1998). Limited field and laboratory data is available regarding ground deformation due to settlement; however, in clean sand layers settlement on the order of 1 to 4 percent of the liquefied layer thickness can occur. Soils most susceptible to liquefaction are loose, non-cohesive soils that are saturated and are bedded with poor draining materials, such as sand and silt layers bedded with a cohesive cap. Based on guidelines set forth in CGS Special Publication 117A (CGS, 2008), screening investigations could be used to determine whether a particular site has obvious indicators for potential failure as a result of liquefaction. Three of these indicators include soil type, soil density, and depth to ground water. Based on previous investigations in the vicinity of the site and mapped soil conditions, in our opinion, the potential for the presence of liquefiable sediments being present is moderate; therefore, we recommend the potential for liquefaction be evaluated as part of the design-level geotechnical investigation. 4.4 LATERAL SPREADING Lateral spreading or lurching typically occurs as a form of horizontal displacement of relatively flat-lying material toward an open face such as an excavation, channel, or body of water. Generally, in soils, this movement is due to failure along a weak plane and may often be associated with liquefaction. As described above, the potential for liquefaction occurring at the site appears to be moderate; however, there are no significant open faces within a reasonable distance of the site where lateral spreading could occur. Therefore, in our opinion, the potential for lateral spreading to affect the site appears to be low. 4.5 GROUND RUPTURE The methods used to estimate liquefaction settlements assume that there is a sufficient cap of non-liquefiable material to prevent ground rupture or sand boils. For ground rupture to occur, the pore water pressure within liquefiable soil layers will need to be great enough to break through the overlying non-liquefiable layer, which could cause ground rupture. Based on data from previous explorations near the site, the potential for liquefaction at the site appears to be moderate; therefore, the potential for ground rupture at the site should be further explored at the time of any site exploration. 4.6 SEISMICALLY INDUCED SETTLEMENT Strong earthquake shaking can cause seismically induced settlement of soil strata, resulting in settlement of near-surface soils. Factors that affect this hazard include soil composition and consistency, the magnitude of loading on native soils, such as from fills and structures, and any Page 6

11 other changes in thickness or consistency abruptly over short distances. The potential for seismically induced settlement in the alluvial soils present is likely low to moderate. 4.7 EXPANSIVE SOILS Expansive soils can undergo significant volume change with changes in moisture content. Expansive soils shrink and harden when dried, and expand and soften when wetted. The plasticity of the surficial soils encountered during our previous investigations near the site indicated the potential for moderate expansion potential; therefore, the potential for future impacts due to expansive soils appear moderate without mitigation. 4.8 EXISTING FILLS As discussed, data in the report by PES Environmental describes and shows the location of a removed UST at the site. Additionally, fill beneath the existing structures is also likely. We anticipate; however, that any existing fills within the proposed building footprint will be removed during the basement excavation. Any remaining fill materials at the site should be further evaluated as part of the design-level geotechnical investigation for the planned site improvements. Likely mitigation would be removal and/or replacement with engineered fill. Provided the fill materials meet the requirements for engineered fill, they could be used on site. Otherwise, they could be stockpiled on site for future use in landscaping or non-structural fill areas. 4.9 LANDSLIDING The site and adjacent areas are topographically flat and are located far from any slopes. The regional scale published landslide themed maps show no landslides or debris flow source areas anywhere near the site (Brabb and Pampeyan, 1972; Mark, 1972; San Mateo County, 2008), nor is there a potential for earthquake induced slope instability (Wieczorek et al., 1985) Therefore, the potential for landsliding to impact the site is low SEISMICALLY INDUCED WAVES The terms tsunami or seiche are described as ocean waves or similar waves usually created by undersea fault movement or by a coastal or submerged landslide. Tsunamis may be generated at great distance from shore (far field events) or nearby (near field events). Waves are formed, as the displaced water moves to regain equilibrium, and radiates across the open water, similar to ripples from a rock being thrown into a pond. When the waveform reaches the coastline, it quickly raises the water level, with water velocities as high as 15 to 20 knots. The water mass, as well as vessels, vehicles, or other objects in its path create tremendous forces as they impact coastal structures. Tsunamis have affected the coastline along the Pacific Northwest during historic times. The Fort Point tide gauge in San Francisco recorded approximately 21 tsunamis between 1854 and The 1964 Alaska earthquake generated a recorded wave height of 7.4 feet and drowned Page 7

12 eleven people in Crescent City, California. For the case of a far-field event, the Bay area would have hours of warning; for a near field event, there may be only a few minutes of warning, if any. A tsunami or seiche originating in the Pacific Ocean would lose much of its energy passing through San Francisco Bay. Based on the study of tsunami inundation potential for the San Francisco Bay Area (Ritter and Dupre, 1972), areas most likely to be inundated are marshlands, tidal flats, and former bay margin lands that are now artificially filled, but are still at or below sea level, and are generally within 1½ miles of the shoreline. The site is approximately 1 mile inland from the San Francisco Bay shoreline, and is approximately 27 feet above mean sea level. We reviewed mapping of the site for Tsunamis, and the potential for inundation due to tsunami or seiche is considered low (California Emergency Management Agency, Coastal Region (2009) FLOODING The site is not designated within a particular zone by the Federal Emergency Management Agency (FEMA) flood map public database; however, based on the hatching within the site area and the map legend, the site is either located within Zone X, described as Areas determined to be outside the 0.2 percent annual chance floodplain, or Zone D, described as Areas in which flood hazards are undetermined, but possible. We recommend the project civil engineer be retained to confirm which zone is the correct zone for the site. SECTION 5: PRELIMINARY CONCLUSIONS From a geotechnical viewpoint, the project should be feasible provided the potential hazards and impacts are mitigated during design and construction. Our discussion of preliminary impacts and mitigation follows. 5.1 PRELIMINARY IMPACTS Descriptions of our preliminary concerns follow the listed concerns. Strong ground shaking Potential for liquefaction-induced settlements High ground water dewatering Proximity of basement excavation to adjacent improvements Presence of undocumented fill Potential for presence of expansive soils Differential movement at on-grade to on-structure transitions Strong Ground Shaking Strong ground shaking is expected at this site, as with most sites in the Bay Area, during a major earthquake in the area. Page 8

13 To mitigate the effects of strong ground shaking, all planned structures should be designed in accordance with the recommendations in a final design-level geotechnical report, and the most recent California Building Code Potential for Liquefaction Induced Settlements As previously discussed, based on previous investigations at the site and mapped soil conditions, and historic high ground water estimated to be as high as 15 feet, in our opinion, the potential for the presence of liquefiable sediments being present is moderate. We recommend the potential for liquefaction be evaluated as part of the design-level geotechnical investigation. In our opinion, the effects of liquefaction can be mitigated. Mitigation methods typically differ based on the soil conditions actually encountered, the depth of liquefiable sediments, and the magnitude of expected settlement due to reconsolidation of liquefied sediments. Typical mitigation methods include designing foundations to tolerate the expected settlement, ground improvement, or the use of deep foundations High Ground Water Dewatering As discussed, we anticipate ground water levels to rise to depths above the planned basement bottom. Considering this, ground water may be present during construction; therefore, we recommend a dewatering system be implemented during construction. Additionally, we recommend the proposed foundation system be designed to resist the potential hydrostatic and uplift forces resulting from high ground water above the planned basement bottom Proximity of Basement Excavation to Adjacent Improvements We anticipate that the basement will extend to within a few feet or less of the property lines. Design of shoring incorporating surcharge loads from adjacent buildings or underpinning of the adjacent structures will likely be required. Restrained temporary shoring to support the twostory excavation will be necessary Presence of Undocumented Fill As discussed, it is likely that undocumented fill is present at the site due to the previous and existing development at the site. Undocumented fill, if not mitigated, could potentially settle, and cause distress to new structures and other improvements. Although any existing fills within the building footprint will likely be removed during the basement excavation, any remaining fill materials can be mitigated, which should consist of the removal of undocumented fill materials. Provided the fill materials meet the requirements for engineered fill, they could be re-used on site as engineered fill. Otherwise, they could be stockpiled on site for future use in landscaping or non-structural fill areas. Page 9

14 5.1.6 Potential for Presence of Expansive Soils Moderately expansive surficial soils were encountered at the site during the previous environmental investigations. To reduce the potential for damage to the planned structures and other improvements, the expansive properties of the native soils will be considered in developing design recommendations for foundations, slabs-on-grade, exterior concrete flatwork, pavements, and other site improvements bearing at grade. In addition, it is important to limit moisture changes in the surficial soils by using positive drainage away from buildings and other hardscaped areas, as well as limiting landscaping watering Differential Movement at On-Grade to On-Structure Transitions Some flatwork areas will likely transition from on-grade support to overlying the basement (onstructure). These transition areas typically experience increased differential movement due to a variety of causes, including difficulty in achieving compaction of retaining wall backfill closest to the wall, or settlement of backfill placed behind shoring when the excavation is not cut neat or there is raveling, requiring backfill behind lagging. We recommend consideration be given to including subslabs beneath flatwork or pavers that can cantilever at least 3 feet beyond the wall at these transitions. If surface improvements are included that are highly sensitive to differential movement, additional measures may be necessary. Additional recommendations will be discussed during the design-level investigation. 5.2 FEASIBLE FOUNDATIONS We have reviewed the mapped conditions and data from previous exploration at the site, and the conditions indicated by other local exploration in the site area. The site appears to be underlain by alluvial soils. In general, these soils can support structures on shallow foundations; however, a reinforced concrete mat should be chosen as the shallow foundation option in order to resist the potential hydrostatic and uplift forces resulting from shallow ground water. The shallow foundation options may vary somewhat depending on actual site conditions and the final level of the basement bottom. If total settlement due to static loads and seismic shaking are excessive, then ground improvement or deep foundations may be required. Should ground improvement or deep foundations be required, they would likely consist of drilled displacement columns, stone columns, precast, prestressed concrete driven piles, or augercast piles (drilled, cast-in-place). The ground improvement types and depths and the length of piles would be affected by the shear strength and types of soils, the pile diameter, the presence of soft, compressible soils, the potential for post-seismic reconsolidation of liquefiable soils, and other factors. The feasibility of these foundations should be evaluated during the design-level investigation. 5.3 FINAL DESIGN-LEVEL GEOTECHNICAL REPORT The preliminary information in this report is based upon review of available published information and our site reconnaissance. No exploration was completed for this initial study; Page 10

15 therefore, we recommend that a final geotechnical investigation including exploration, laboratory testing, and analysis be completed once final development details are available. SECTION 6: CLOSURE AND LIMITATIONS We hope this report provides the information needed at this time. This report, an instrument of professional service, has been prepared for the sole use of Windy Hill Property Ventures and their representatives specifically to support their review of the 4th Avenue and Railroad Avenue Mixed Use project in San Mateo, California. The opinions and conclusions presented in this report have been formulated in accordance with accepted geotechnical engineering and engineering geology practices that exist in Northern California at the time this report was prepared. No warranty, expressed or implied, is made or should be inferred. Recommendations in this report are based upon literature review and professional experience. No subsurface exploration of the project area was performed for this study. If variations or unsuitable conditions are encountered during construction, Cornerstone should be contacted to provide supplemental recommendations, as needed. Windy Hill Property Ventures may have provided Cornerstone with plans, reports and other documents prepared by others. Windy Hill Property Ventures understands that Cornerstone reviewed and relied on the information presented in these documents and cannot be responsible for their accuracy. Cornerstone prepared this report with the understanding that it is the responsibility of the owner or his representatives to see that the recommendations contained in this report are presented to other members of the design team and incorporated into the project plans and specifications, and that appropriate actions are taken to implement the geotechnical recommendations during final design and construction. Conclusions and recommendations presented in this report are valid as of the present time for the development as currently planned. Changes in the condition of the property or adjacent properties may occur with the passage of time, whether by natural processes or the acts of other persons. In addition, changes in applicable or appropriate standards may occur through legislation or the broadening of knowledge. Therefore, the conclusions and recommendations presented in this report may be invalidated, wholly or in part, by changes beyond Cornerstone s control. This report should be reviewed by Cornerstone after a period of three (3) years has elapsed from the date of this report. In addition, if the current project design is changed, then Cornerstone must review the proposed changes and provide supplemental recommendations, as needed. An electronic transmission of this report may also have been issued. While Cornerstone has taken precautions to produce a complete and secure electronic transmission, please check the electronic transmission against the hard copy version for conformity. Recommendations provided in this report are based on the assumption that Cornerstone will be retained to provide observation and testing services during construction to confirm that Page 11

16 conditions are similar to that assumed for design, and to form an opinion as to whether the work has been performed in accordance with the project plans and specifications. If we are not retained for these services, Cornerstone cannot assume any responsibility for any potential claims that may arise during or after construction as a result of misuse or misinterpretation of Cornerstone s report by others. Furthermore, Cornerstone will cease to be the Geotechnical- Engineer-of-Record if we are not retained for these services. SECTION 7: REFERENCES Bortugno, E.J., McJunkin, R.D., and Wagner, D.L., 1991, Map showing recency of faulting, San Francisco-San Jose quadrangle, California: California Division of Mines and Geology Regional Geologic Map Series, Map 5A, Sheet 5, scale 1: 250,000. Brabb, E.E., Pampeyan, E.H., and Bonilla, M.G., 1972, Landslide susceptibility in San Mateo County, California: U.S. Geological Survey Basic Data Contribution 43, scale 1:62,500. Brabb, E.E. and Hanna, W.F., 1981, Maps showing aeromagnetic anomalies, faults, earthquake epicenters, and igneous rocks in the southern San Francisco Bay region, California: U.S. Geological Survey, Geophysical Investigations Map GP-932, scale 1:125,000. Brabb, E.E., and Olson, J.A., 1986, Map showing faults and earthquake epicenters in San Mateo County, California: U.S. Geological Survey Miscellaneous Investigations Series Map I F, scale 1:62,500. Brabb, E.E., Taylor, F.A., and Miller, G.P., 1982, Geologic, scenic, and historic points of interest in San Mateo County, California: U.S. Geological Survey, Miscellaneous Investigations Series Map I-1257-B, scale 1:62,500. Brabb, E.E., and Pampeyan, E.H., 1983, Geologic map of San Mateo County, California: U.S. Geological Survey Miscellaneous Investigations Series Map I-1257-A, scale 1:62,500. Brabb, E.E., Graymer, R.W., and Jones, D.L., 1998, Geology of the onshore part of San Mateo County, California: A digital database: U.S. Geological Survey Open-File Report , U.S. Geological Survey, Menlo Park, CA. Brabb, E.E., Graymer, R.W., and Jones, D.L., 2000, Geologic map and map database of the Palo Alto 30 X 60 quadrangle, California: U.S. Geological Survey Miscellaneous Field Studies Map MF-2332, Version 1.0. California Department of Conservation Division of Mines and Geology, 1998, Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada, International Conference of Building Officials, February, California Division of Mines and Geology, 1974, Official map of Alquist-Priolo Earthquake Fault Hazard Zones, San Mateo Quadrangle: California Division of Mines and Geology, scale 1:24,000. Page 12

17 California Division of Mines and Geology, 2008, Guidelines for Evaluating and Mitigating Seismic Hazards in California, Special Publication 117A, March, Federal Emergency Management Administration (FEMA), 2015, FIRM City of San Mateo, California, Community Panel # 06081C0154F. Graymer, R.W., Bryant, W., 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, scale 1:275,000. Helley, E.J., LaJoie, K.R., Spangle, W.E. and Blair, M.L., 1979, Flatland deposits of the San Francisco Bay region, California their geology and engineering properties, and their importance to comprehensive planning: U.S. Geological Survey Professional Paper 943, scale 1:125,000. Knudsen, K.L., Sowers, J.M., Witter, R.C., Wentworth, C.M., and Helley, E.J., 2000, Preliminary maps of Quaternary deposits and liquefaction susceptibility, nine-county San Francisco Bay region, California: a digital database: U.S. Geological Survey Open-File Report , scale 1:275,000. Idriss, I.M., and Boulanger, R.W., 2008, Soil Liquefaction During Earthquakes, Earthquake Engineering Research Institute, Oakland, CA, 237 p. Pampeyan, E.H., 1994, Geologic map of the Montara Mountain and San Mateo 7.5' quadrangles, San Mateo County, California: U.S. Geological Survey, Miscellaneous Investigations Series Map I-2390, scale 1:24,000. Perkins, J.B., 1987, Maps showing cumulative damage potential from earthquake ground shaking, San Mateo County, California: U.S. Geological Survey, Miscellaneous Investigations Series Map I-1257-I, scale 1:62,500. Nason, R.D., 1980, Damage in San Mateo County, California, in the earthquake of 18 April 1906: U.S. Geological Survey Open File Report , 49 p. San Mateo County, 2008, Hazards Mitigation Maps: on-line site at Thompson, J.M. and Evernden, J.F., 1986, Map showing predicted seismic-shaking intensities of an earthquake in San Mateo County, California, comparable in magnitude to the 1906 San Francisco earthquake: U.S. Geological Survey, Miscellaneous Investigations Series Map I H, scale 1:62,500. Townley, S.D. and M.W. Allen, 1939, Descriptive Catalog of Earthquakes of the Pacific Coast of the United States, 1769 to 1928: Bulletin of the Seismological Society of America, Vol. 29, No. 1, pp Page 13

18 The Tsunami Modeling Working Group, 2013, The SAFRR tsunami scenario -- generation, propagation, inundation, and currents in ports and harbors: U.S. Geological Survey, Open-File Report OF D, scale 1:65,000. U.S. Geological Survey and California Geological Survey, 2011, Quaternary fault and fold database for the United States, accessed December 15, 2001, from USGS web site: Weiczorek, G.F., Wilson, R.C., and Harp, E.L., 1985, Map showing slope stability during earthquakes in San Mateo County, California: U.S. Geological Survey Miscellaneous Investigations Series Map I-1257-E. scale 1:62,500. Working Group on California Earthquake Probabilities, 2015, The Third Uniform California Earthquake Rupture Forecast, Version 3 (UCERF), U.S. Geological Survey Open File Report (CGS Special Report 228). KMZ files available at: Youd, T.L., and Perkins, J.B., 1987, Map showing liquefaction susceptibility of San Mateo County, California: U.S. Geological Survey Miscellaneous Investigations Series Map I-1257-G, scale 1:62,500. Aerial Photos Reviewed Date Type 1946 vertical black & white 1956 vertical black & white 1958 vertical black & white 1968 vertical black & white 1980 vertical black & white 1993 vertical black & white 2002 vertical black & white 2005 vertical black & white 2009 vertical black & white 2010 vertical black & white 2012 vertical black & white Historic Topographic Maps Reviewed Date Type :62, :62, :24, :24, :24,000 Page 14

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