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V A: ',':[..,2.-,1, ,' �4 : r, . � t r . , - ,,-- . ,._ w ; • • y P+ `' ".....':z',. - fi x -j , v � (y �.fi a A t • •t � �,. - ,T, x. .I ,� - ,r, Y -' .```^• , } ,J- ;. a'.•Y i. • r `7 . 4 '•Y 1� URS January 30, 2004 I Tigard - Tualatin School District 23J 6960 SW Sandburg Street Tigard, Oregon 97223 l Attn: Mr. Stephen Poage Director of Capital Projects Re: Site - Specific Seismic Hazards Report Proposed Tigard High School Remodel Tigard- Tualatin School District 23J Tigard, Oregon , URS Job No: 25695560.10001 Dear Mr. Poage: We are pleased to submit herewith our report entitled "Site- Specific Seismic Hazards Report, Proposed Tigard High School Remodel, Tigard- Tualatin School District 23J, Durham, Oregon." This report formally documents our conclusions and recommendations regarding the proposed project. It has been our pleasure to assist you with this project. Should you have any questions regarding the contents of this report, please call us at your convenience. Yours very truly, , Y �� F p PROpe URS 4�G1N� �� 72276PE r ' OREGON ti Q OT 10 Hy J. R AG / /SIIV7 Timoth J. Richter, P.E. .rian . i lman, Ph.D., P.E. ' Project Engineer i EXPIRE.S: 7,I' ' I Manager, Geotechnical Engineering 1 URS Corporation 111 SW Columbia, Suite 900 Portland, OR 97201 -5814 Tel. 503.222.7200 1 Fax: 503.222.4292 TABLE OF CONTENTS I 1. General 1 - I 1 General 1 -1 1.2 Scope of Work .. . .1 -1 1 1.3 Site Exploration 1 -1 2. Geologic Structure 2 - 1 2.1 Regional Structure 2 -1 2.2 Site Geology 2 -1 l 3. Seismic Hazard Assessment 3 - 1 3.1 Earthquake Effects - General .. 3 -1 3 2 Historical Seismicity 3 -1 3.2.1 Significant Earthquakes 3 -2 3.2.2 Earthquake Sources 3 -4 3.3 Earthquake Sources 3 -4 3.3.1 Cascadia Convergent Margin 3 -5 3.3.2 Crustal Faulting 3 -5 1 - 3.3.3 Helvetia Fault Zone 3 -8 3.3.4 Newberg Fault 3 -8 3.3.5 Portland Hills Fault Zone 3 -8 .11 3.3.6 Bolton Fault 3 -9 3.3.7 Mt. Angel Fault 3 -10 3.3.8 East Bank Fault 3 -10 .i , 3.3.9 Oatfield Fault 3 -11 3.3 10 Clackamas River Fault Zone 3 -11 3.3.11 Grant Butte, Damascus, Tickle Creek Fault Zone 3 -1 1 3.3.12 Other Fault Zones 3 -12 3.3.13 Cascadia Subduction Zone 3 -12 3.4 Review of Probabilistic Seismic Hazard Analyses 3 -13 3.4.1 Geomatrix 1995 Probabilistic Study.. .. 3 -13 3.4.2 URS/DOGAMI 2000 Portland Metropolitan Study 3 -14 p 3.4.3 1998 OSSC Spectral Ordinates . .. ....... .. .... .................. .. .... 3-14 3 4.4 Site Specific Response Spectrum .............. 3 -15 3.4.5 Results Comparison 3 -16 3.5 Recommended Design Ground Motions 3 -17 3.6 Seismic Hazards ......... 3 -17 3.6 1 Liquefaction Hazard 3 -18 3.6 2 Tsunami /Seiche Hazard .............................. . 3 -19 3.6 3 Seismic Slope Stability Hazard 3 -19 I 3.6.4 Surface Rupture Hazard .3 -19 3.6.5 Ground Shaking Amplification Hazard.. .. 3 -19 i List of Tables Table 1: OSSC 1998 Seismic Values 3 -15 Table 2: Selected Earthquakes for Spectral Analyses 3 -16 Table 3: Comparison of Peak Ground Accelerations for Hazard Modeling 3 -16 I List of Diaarams, Diagram 1: Oregon Crustal Faults 3 -5 ii ill Diagram 2: Tectonic Structures of the Tualatin Basin 3 -7 Diagram 3: Earthquake Scenario Maps for the Portland Metropolitan Area 3 -14 List of Figures Figure 1 Site Vicinity Map Figure 2 Modified Mercalli Intensity (MMI) Scale Description Figure 3 Oregon Map of Historical Earthquakes, 1841 through 2002 Figure 4 Earthquake Design Suite I Figure 5 URS 2004 Design Spectrum List of Appendices Appendix A Site Exploration Logs and Shear Wave Test Results URS i I SECTION ONE General 1.1 GENERAL This report presents the results of our site - specific seismic hazards investigation performed for the proposed renovation of Tigard High School in Tigard, Oregon. This work was completed in accordance with our proposal to Tigard- Tualatin School District 23J dated December 18, 2003. The high school is located at 9000 SW Durham Road in Tigard, approximately 400 feet east of the intersection of SW Durham Road and SW 92 " Avenue in Tigard. The purpose of this seismic hazards report is to procure and review the subsurface information pertaining to this site, and to provide detailed hazard assessment in conformance with Section 1804 of the 1998 Oregon Structural Specialty Code (OSSC). This assessment along with supporting data is documented in this report. 1.2 SCOPE OF WORK The scope of this investigation included completion of the following: 1) Development of the site response models for a suite of earthquakes similar to those that may be experienced at this site. 2) Description of the geologic setting including regional geology, site topography, 1 11' subsurface stratigraphy, and groundwater. 3) Description of the seismic setting including the regional tectonic framework, historical 01 seismicity, and potential earthquake sources. 4) Description of the subsurface exploration investigation (drilling and /or test pits) developed for the project specific needs 5) Laboratory Testing to support hazard assessment calculations (liquefaction, lateral spread, slope instability, etc.) as applicable. 6) Probabilistic and deterministic analyses to assess design earthquake ground motions. 7) Evaluation of seismic hazards landslides, liquefaction, regional subsidence /collapse, fault J surface rupture, and tsunami /seiche inundation. 8) Site drawing showing subsurface exploration locations. 9) Five copies of the Seismic Hazards Report. One copy must be submitted to the Department of Geology and Mineral Industries ( "DOGAMI "). A second copy is required for TTSD's peer review. The others will go to TTSD, the Engineer and the Architect. 1.3 SITE EXPLORATION Near- surface geologic information from the geotechnical borehole logs coupled with the detailed log from the water well completed on the school property in 1953 (Washington County Well # 011707) indicates that the site is underlain by approximately 380 feet of interbedded sands, silts, and clays associated with the Quaternary Alluvial Deposits mapped by Madin (1990). The Quaternary alluvium is underlain by approximately 200 feet of deposits interpreted to be Troutdale Formation gravels. Columbia River Basalt bedrock was encountered 590 feet below the ground surface. (Well log attached in Appendix A of Report). URS 1 -1 r' SECTION ONE General I The shear wave profile of the top 85 feet of soil was constructed using measurements obtained in situ using a Cone Penetrometer Testing (CPT) apparatus. Shear wave velocity measurements 111 were taken every 3 meters (10 feet). The results of this CPT investigation are presented on the Shear Wave Velocity Profile included in Appendix A. URS I i 1 -2 r SECTION TWO Geologic Structure 2.1 REGIONAL STRUCTURE 1111 , The site is located in the northern Willamette Valley physiographic province, an elongated north - south trending alluvial valley that lies between the Oregon Coastal Mountain Range and the Cascade Mountain Range to the west and east, respectively (Orr, et. al., 1992). The Northern Willamette Valley has undergone substantial structural deformation since the Eocene, resulting in the Portland fold belt as defined by Unruh et al. (1994). The tectonic underpinnings of the Portland Fold Belt are not well understood and are further complicated by the fact that this area lies in a transition zone between the rotating Coast Range forearc block and the continental interior (Wells et al, 1998). ' Specifically, the project site is located in the Tualatin Basin, a northwest trending synclinal subbasin to the Willamette Valley basin (Unruh et al., 1994). The Tualatin Basin is fault bound by structurally controlled, northwest - trending highlands, specifically along its northeastern margin by the Portland Hills and on the southwestern edge by the Chehalem Mountians (Madin, 1990; Trimble, 1963; Hart and Newcomb, 1965; Schlicker and Deacon, 1967; Burns et al., 1997). The two highlands are parallel to mapped regional faults including the East Bank fault, the Portland Hills fault, the Oatfield fault, the Mollala -Canby fault, the Gales Creek fault, the Newberg fault, and the Mt. Angel fault. Internal structures of the basin include the faulting that has resulted in the formation of the Bull Mountain and Pete's Mountain anticlines. Seismic reflection and subsurface borings indicate that the Neogene structure of the Tualatin Basin is composed of a large, gently warped, northern subbasin with few faults cutting into the sediments from the Columbia River Basalt Group (CRBG) bedrock, and a smaller, more complexly faulted, southern subbasin south and east of the Beaverton Fault (Wilson, 1997). Cooper and Bull Mountains are probably Pleistocene -aged uplifts that have disrupted the original northwest - southeast axis of the Tualatin Basin. (Wilson, 1997) The site is located at the approximate axis of a local synclinal trough (southern subbasin from Wilson, 1997) as shown by the basement isopach contours mapped by Madin (1990). This trough has developed as the west -to -east flow of the Tualatin River has incised within the local structural downwarp between Bull Mountain and Iron Mountain to the northwest and northeast 1 , respectively, and Pete's Mountain anticline to the south (Burn's et al, 1997). Fault patterns cutting through the CRBG and Neogene sediments in the eastern part of the Tualatin Basin may reflect at least two episodes of structural activity: a middle to upper Miocene period involving the Portland Hills Fault and possibly the Oatfield Fault along with thrust faults in the Tualatin Mountains /Portland Hills; and a Pleistocene period involving activity of the Beaverton Fault and other faults around Cooper and Bull Mountains (Wilson, 1997). Comparison of Neogene basin evolution among Willamette Valley deposition centers reveals similarities in geophysical properties, sediment thickness, and subsidence timing between the Tualatin Basin and the Northern Willamette Basin. The Portland, Stayton, and Southern Willamette Basins appear to have stopped significant subsidence in the upper Pliocene or lowest Pleistocene (Wilson, 1997). 2.2 SITE GEOLOGY • As indicated in Section 3.3 of this report, the site is underlain by approximately 380 feet of interbedded sands, silts, and clays associated with the Quaternary Alluvial Deposits laid down in URS 2 -1 I SECTION TWO Geologic Structure the historic channels of the Tualatin River as mapped by Madin (1990). The Quaternary alluvium is underlain by approximately 200 feet of deposits interpreted to be Troutdale Formation gravels. In the water well completed on the school property in 1953 (Washington County Well # 011707), Columbia River Basalt bedrock was encountered 590 feet below the ground surface. pi I r 1 i I URS 2 -2 SECTION THREE Seismic Hazard Assessment 3.1 EARTHQUAKE EFFECTS - GENERAL Several factors control the level and character of earthquake ground shaking at a site. Generally, these factors are: (1) rupture dimensions, geometry, and orientation of the causative fault; (2) distance from the causative fault; (3) magnitude of the earthquake; (4) the rate of attenuation of the seismic waves along the propagation path from the source to site; and (5) site factors including the effects of near- surface geology particularly from soils and unconsolidated sediments. Other factors, which vary in their significance depending on specific conditions, include slip distribution along the fault, rupture process, footwall/hanging -wall effects, and the effects of crustal structures such as basins. 3.2 HISTORICAL SEISMICITY Historically, the Portland region has been characterized by a moderate level of seismicity with the largest earthquakes not exceeding magnitude (M) 6 (Bott and Wong, 1993). A historical earthquake catalog of all known events in northwestern Oregon and southwestern Washington for the period 1841 to 2000 was compiled including data acquired from: a catalog compiled by Woodward -Clyde Consultants for DOE Hanford; Ludwin (1991); University of Washington; National Earthquake Information Center; Stover, Reagor and Algermissen; the Decade of North American Geology; and the Council of the National Seismic System earthquake catalog. This catalog contains over 18,000 events, with a large percentage associated with the St. Helens seismic zone. Only four earthquakes are M 6.0 or larger and these all occurred at distances greater than 80 km from the Tigard High School site. Approximately 38 earthquakes in the catalog have magnitudes between M 5.0 to 5.9, the largest of which is the 1993 (M 5.6 Scotts Mills earthquake. Historical earthquake epicenters in Oregon between 1841 and 2002 have recently been compiled on a map by the Oregon Department of Geology and Mineral Industries (DOGAMI) (Niewendorp and Neuhaus, 2002). This compilation is shown on Figure 3. In characterizing earthquake occurrence, historical earthquakes can generally be divided into pre - instrumental and instrumental periods. Prior to adequate seismographic coverage, the detection of earthquakes was generally based on direct observation and felt reports. Thus results are strongly dependent on population density and distribution. This part of the Pacific Northwest is typical of much of the western United States, and was sparsely populated in the 1800's. Therefore the record of pre- instrumental earthquakes shows varying degrees of completeness. The pre - instrumental historical record is estimated to be complete for earthquakes of Richter local magnitude (ML) 5 and larger since about 1850 for the Portland region (Bott and Wong, 1993). Seismograph stations were established in 1906 in Seattle and 1944 in Corvallis, but adequate seismographic coverage of small events (M < 3.0) did not begin in northwest Oregon until about 1980 when the University of Washington expanded its regional network. The historical record is complete for M 2.5 and greater only since 1980 (Bott and Wong, 1993). I V RS 3 -1 1 SECTION THREE Seismic Hazard Assessment 3.2.1 Significant Earthquakes Significant earthquakes and earthquakes greater than M 6.0 in the region are discussed below. 1872 North Cascades Earthquake On 15 December 1872, a large earthquake occurred in the wilderness of central Washington with an approximate M 7.4 (Malone and Bor, 1979). The exact source of the earthquake is unknown. The event generated an approximate intensity of MM IV -V in the region of Tigard High School (Woodward -Clyde Consultants, 1992). 1873 Crescent City Earthquake On 23 November 1973 at 05:00 Greenwich Mean Time (GMT) an earthquake of estimated M 7.3 (Bakun, 2000) occurred near the Oregon - California border east - southeast of Brookings, though there are large uncertainties as to its exact location. This earthquake may be a rare example of an intraslab event in western Oregon (Ludwin et al, 1991; Wong, 1997). The event had a maximum intensity of MM VIII, and an intensity of MM III -IV in the region of Tigard High School (Toppozada et al., 1981). 1877 Portland Earthquake The earliest known historical earthquake in the Portland region occurred on 12 October 1877. Two events were actually reported on this day, one at about 17:00 GMT, which probably occurred near Cascades, Washington and had a maximum intensity of MM III. The other event at 21:53 GMT occurred near Portland and had a maximum intensity of MM VII. The larger of the two events, it has an estimated magnitude of ML 5'/4 (Bott and Wong, 1993). At the Tigard High School site, the intensity was estimated to be MM IV (Bott and Wong, 1993). 1939 Southern Puget Sound Earthquake On 13 November 1939 at 7:45 GMT, an earthquake of surface wave magnitude (Ms) 5 occurred in southern Puget Sound. It had a maximum intensity of MM VII and an intensity of MM IV in the region of the school site (Stover and Coffman, 1993). 1949 Puget Lowland Earthquake 1111 On 13 April 1949 at 19:56 GMT, the largest historic event in the Puget Sound region occurred northeast of Olympia, Washington, with a body wave magnitude (m of 7.1. The event occurred at a depth of 54 km within the Juan de Fuca plate. Eight people were killed, many injured and property damage was sustained at a loss of $25 million. The intensity in the region of the school site was MM VI -VII (Thorsen, 1986). URS 3 -2 • SECTION THREE Seismic Hazard Assessment 1962 Portland Earthquake On 6 November 1962 at 3:37 GMT, an earthquake occurred 15 km northeast of downtown Portland with a magnitude of M 5.2 to 5.5, a depth of 16 km, and a maximum intensity of MM VII. This earthquake was felt throughout northwest Oregon and southwest Washington. The intensity in the region of the school was MM V -VI (Wong and Bott, 1995). This is the second largest earthquake known to have originated in the Portland region (Bott and Wong, 1993). 1965 Puget Lowland Earthquake On 29 April 1965 at 15:29 GMT, the second largest known event in the southern Puget Sound occurred north of Tacoma with a m 6.5. The event, an intraslab earthquake, occurred at a focal depth of 60 km and was widely felt. Six people were killed and damage reached an estimated $12.5 million. The earthquake had a maximum intensity of MM VIII and a probable intensity of MM V in the vicinity of Tigard High School (Thorsen, 1986). 1981 Elk Lake Earthquake On 14 February 1981 at 6:09 GMT, the largest known earthquake associated with the St. Helens seismic zone occurred with a m 5.1. The aftershock zone delineates a fault zone 5 to 12 km in depth. The maximum intensity of MM VI was reported for the epicentral region and an intensity of MM V for the school vicinity (Bott and Wong, 1993). 1993 Scotts Mills Earthquake On 25 March 1993 at 13:35 GMT, an earthquake occurred near Scotts Mills in western Oregon with a magnitude of M 5.6, a depth of 16 km, maximum intensity of MM VII, and an intensity MM V -VII in the school vicinity. It caused over $28 million in property damage. This earthquake is thought to have occurred on the Mount Angel fault. Through 1994, over 300 aftershocks had been recorded (Thomas et al., 1996). 2001 Nisqually Earthquake On 28 February 2001 at 18:54 GMT, the third largest known event in the southern Puget Sound region occurred 17.6 -km northeast of Olympia with a M 6.8. The event, an intraslab earthquake with a normal -slip mechanism, occurred at a focal depth of 52.4 km and was widely felt throughout the Pacific Northwest. One person was killed, 407 people were injured, the SeaTac and King County airport control towers were rendered unusable, and damage reached an estimated $250 million. The earthquake had a maximum intensity of MM VIII and a felt intensity of MM IV in the vicinity of Tigard High School (USGS, 2004). 3.2.1.1 Summary The strongest ground shaking that the area of Tigard High School has historically experienced g g g g g Y P appears to be MM VI -VII in the 1949 earthquake and MM V -VII in the 1993 Scotts Mills event. An MMI VII intensity is roughly equivalent to 0.18 to 0.34g (Wald et al., 1999). URS 3 -3 1 SECTION THREE Seismic Hazard Assessment 3.2.2 Earthquake Sources The Pacific Northwest has four types of seismic sources due to the presence of the Cascadia subduction zone. These sources include (1) the subduction zone megathrust, which represents the boundary (interface) between the downgoing Juan de Fuca plate and the overriding North American plate; (2) faults located within the subducting Juan de Fuca plate (referred to as the intraplate or intraslab region); (3) crustal faults principally in the North American plate; and (4) 111 volcanic sources beneath the Cascade Range (Wong and Silva, 1998). In the past two decades, significant geologic, seismologic, and geophysical studies have been undertaken to investigate seismic sources in the Pacific Northwest. Such studies, particularly along the coast of the Pacific Northwest, have been the key to our understanding of the earthquake processes within the Cascadia subduction zone. Few paleoseismic studies to investigate crustal faults, however, have been performed west of the Cascades because of dense vegetation, relatively rapid erosion rates, and past glaciation, which makes it difficult to find evidence of young faulting (e.g., Pezzopane, 1993). Alternative approaches such as subsurface imaging are now being carried out in the Portland area (e.g., Blakely et al., 1995) and the Puget Sound region (e.g., Johnson et al., 1999). In the following section, we identify and characterize the seismic sources that are significant to seismic hazards near the school. As specified in OSSC 1804.2.1.1, the probable source faults must all be individually examined for contribution to site hazards. For this analysis, the earthquakes need to be defined for each seismic source considered in the seismic hazard assessments by their respective Maximum Credible Earthquake (MCE). The MCE is commonly defined as "the largest earthquake that is capable of being produced from a source, structure, or region, under the currently known tectonic framework. It is a rational and believable event that can be supported by all known geologic and seismologic data. An MCE is determined by judgment considering the geologic evidence of past movement and the recorded seismic history of the area." We adopt this definition in these assessments. These MCE values discussed in the following were utilized in the 2000 and 2001 URS Probabilistic Studies discussed below. 3.3 EARTHQUAKE SOURCES Seismic source characterization is concerned with three fundamental elements: (1) the identification of significant sources of earthquakes; (2) the maximum size of these earthquakes; and (3) the rate at which they occur. The order of the faults described below is based on the distance from the mapped or projected trace of the fault to the proposed pipeline corridor; the closest faults are described first. The Pacific Northwest has four types of seismic sources due to the presence of the Cascadia subduction zone. These sources include (1) the subduction zone megathrust, which represents the boundary (interface) between the downgoing Juan de Fuca plate and the overriding North American plate; (2) faults located within the Juan de Fuca plate (referred to as the intraplate or intraslab region); (3) crustal faults principally in the North American plate; and (4) volcanic sources beneath the Cascade Range (Wong and Silva, 1998). URS 3 -4 I SECTION THREE Seismic Hazard Assessment I 3.3.1 Cascadia Convergent Margin I The seismotectonic setting of northwestern Oregon is primarily driven by convergence between the Juan de Fuca and North American plates. The northeastward (N50 °E) motion of the Juan de I Fuca plate relative to the North American plate is accommodated by underthrusting and subduction of the Juan de Fuca plate beneath the continent along the Cascadia trench. Oblique subduction at the Cascadia margin occurs at a rate of approximately 40 to 45 mm/yr, and has I created a complex, seismically active convergent margin and volcanic arc in the Pacific northwest (Wells et al., 1998; Ludwin et al., 1991). The chain of active volcanoes that result from plate subduction make up the Cascade Range, I which extends roughly north -south through Oregon, and stretches from northern California to British Columbia. Other major tectonic elements of the plate boundary include an active accretionary wedge complex in the offshore region east of the trench and a deformed Tertiary forearc basin that lies seaward of the volcanic arc. The present -day Coast Range, Portland Basin, and Willamette Valley stand where marine sediments and fragments of oceanic crust were accreted, and later deformed, during early Tertiary plate convergence and subduction (Unruh et al., 1994). Oblique subduction, such as the kind found along the Oregon coastline, can produce arc - parallel 1 motion of the forearc and adds an additional component of crustal deformation from the relative motions of forearc blocks (Wells et al., 1998; McCaffrey, 1994). Wells et al. (1998) break up the Cascadia forearc into three segments based on contrasting patterns of Neogene deformation, seismicity and volcanism, and crustal structure. Northwestern Oregon sits on the Oregon Coastal forearc block whose boundaries extend from the Oregon - Washington border, south to the 1 Klamath Mountains (Wells et al., 1998). During the Cenozoic period, the Oregon Coastal block has been rotating clockwise with respect to stable North America at about 1.5 ° /m.y. (Magill et al., 1982), creating a diffuse transfer zone in the Portland region between the northward moving I forearc block and the continental interior (Stanley et al., 1996; Weaver and Smith, 1983). 3.3.2 Crustal Faulting ,Il The transfer zone that accommodates the rotation of the forearc block spans Oregon west of the ' ' ! ,Qc "`„ ,- y Cascade Mountains, and has had a complex - ; � J �- -( • X.. +' deformational history since the middle Miocene i ' `' " - Y .'�' that includes elements of compression, extension, — I �' ,,..11- 71 i and dextral slip. This slip manifests in the -, i `�, seismogenic portions of the crust through crustal -r � f faulting. � � � � '' I Because of their proximity, crustal faults are -, { { possibly the most significant seismic sources to. - - - % 4 ' i ' inland sites. Studies by Pezzopane (1993) and ,.V'.- '71 . 1 J \ I i 4 :.w Geomatrix Consultants (Geomatrix) (1995) show Diagram 1: Map of known crustal faults in Oregon. Red that at least 70 crustal faults that may have faults denote active or potentially active faults(DOGAMl, I earthquake potential exist in Oregon. Many of 2004, clipped website image URNS 3 -5 I I SECTION THREE Seismic Hazard Assessment these faults were unknown or not recognized as being seismogenic a decade ago. Although the largest known crustal earthquake in western Oregon is only about Mw 6 (Wong and Bott, 1995), potential exists for events of Mw 61/4 or greater along several recognized faults including the Portland Hills and the recently discovered East Bank faults in Portland as well as the Gales Creek -Mt. Angel fault zone (Wong et al., 1999). As discussed earlier, the Mt. Angel fault is the possible source of the 1993 Scotts Mills Mw 5.6 earthquake. Several crustal faults occur in the vicinity of Tigard High School site that are either active or potentially active. There has not been a historic - surface rupture earthquake on any fault within northwest Oregon and, to date, paleoseismic investigations of the regional faults has been limited. However, historical seismicity in the region appears, in a few cases, to be associated with mapped faults. In addition, some regional seismotectonic studies have been conducted that provide preliminary data regarding the potential activity of these faults. The major fault features that have an effect on seismic hazards within the basin as identified by Unruh et al (1994) are the Portland Hills Fault Zone (which includes the East Bank and Oatfield Faults), the Newberg Fault, the Grant Butte Fault, the Mt. Angel Fault, and the Bolton Fault. These features are shown on Diagram 2. Several fault features that should be considered in a seismic hazard assessment, but are not labeled on the Unruh et al (1994) map include the Clackamas River Fault Zone and the Helvetia Fault. 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' ' ' 'VALLEY • 1 - , a" '; - ' - ' '-' - - -t';'" ,- -,'.'"-„ , " ', - „ " • ,',, - : ,: -•'.;',', ',:-;:., 4 , .A. . :,',,,,','-', ,; . ,,,,-:,,' , • •,-- - ' : '',.•:;,- ' .- - -- :1- , 1.7-.1':-.H, ''''F '''''''''''''''''';''' ' I Diagram 2: Tectonic Structures of the Tualatin Basin taken from Unruh et a. (1994) 3 -7 MS II I SECTION THREE Seismic Hazard Assessment Several interpretations have been proposed to describe the style of faulting and the kinematic setting of the Portland Hills fault. Based on the interpretation of surface geology, geomorphology, gravity data, and seismicity, Beeson et al. (1985; 1989) have described the Portland Hills fault as a structurally complex dextral strike slip zone with minor normal faulting. Yelin and Patton (1991) consider the Portland Hills fault to be an active right - lateral strike -slip fault within an en echelon, releasing step of a large dextral slip zone. In contrast, the Portland Hills are thought by some researchers (Beeson et al., 1989; Phillips, 1987; Unruh et al., 1994) to be the surface expression of an anticline associated with the hanging wall of a southwest- dipping thrust fault. Although, the age of the most recent event along the Portland Hills fault is not clearly understood, the recent geophysical imaging and fault trenching at Rowe Middle School suggests that the structure is high -angle, dipping toward the northeast with normal displacement �j (Hemphill -Haley et al., 2002). Direct evidence for lateral displacement has not been observed, however, the steep angle of the fault suggests a component of lateral motion may be present. Furthermore, the data indicate that over 100m of vertical offset and tilting of the Columbia River Basalt at depth occurs alongside folding and faulting of the Missoula Flood Deposits up to 6 feet near the surface (Hemphill -Haley et al, 2002). The observed deformation is consistent with a (minimum) 400 - meter -wide strike -slip fault zone with a minor dip -slip component that has ruptured at least 2 times with major earthquakes within the last 12,000 to 15,000 years (Hemphill -Haley et al, 2002). This evidence leads us to define the Portland Hills fault as active. PI A swarm of M < 3.5 earthquakes occurred at the northern end of the Portland Hills fault in 1991, and focal mechanisms from the largest event suggest a mixed right- lateral and reverse mechanism for the fault (Blakely et al., 1995). Based on a maximum estimated length of 62 km ' (Wong et al., 2000), which includes projection of the fault to the south of the Portland Hills, an estimated MCE of M 7.2 is calculated for the Portland Hills fault. ' 3.3.6 Bolton Fault The Bolton fault appears at the surface as a 9 -km -long northwest- striking structure located t between the northern Willamette Valley and the Portland Basin. At its closest approach the fault is about 5.3 km from the Tigard High School site. Beeson et at (1989) map the fault as a high - angle, down -to- the - northeast structure that displaces late Pleistocene (11 to 14 ka) flood deposits. Unruh et al. (1994) were unable to confirm displacement in stream exposures of Miocene Columbia River Basalts or Plio - Pleistocene ( ?) conglomerates. Instead, they suggest that scarps along the fault may be the result of erosion. Although Unruh et al. (1994) did not find evidence for late Pleistocene faulting, they classified the fault as potentially active because of limited exposures and significant uncertainties about the activity of the fault. Geomatrix (1995) also considered the Bolton fault to be potentially active. Although the maximum mapped surface length of the Bolton fault is 9 km, the estimated minimum magnitude earthquake that we consider sufficiently large to produce surface rupture is M 6.5. This MCE corresponds with an associated surface rupture length of 17 km. I 3 -9 I SECTION THREE Seismic Hazard Assessment 3.3.7 Mt. Angel Fault The Mount Angel fault is a 24- to 32 -km -long northwest- trending fault located approximately 23.5 km to the southwest of Tigard High School. The fault strikes northwest and dips steeply to I the northeast. The fault is mapped at the subsurface based on seismic reflection lines, water well logs, and seismicity (Geomatrix, 1995; Yeats et al., 1991) that indicate the top of the Columbia River Basalt group and Mio- Pliocene fluvio- lacustrine deposits are displaced by the fault. Recent investigations using high- resolution seismic reflection and refraction imaging along the Mt. Angel fault suggest that faulting has displaced Missoula flood deposits, indicating Holocene activity (Liberty et al., 1996, Ian Madin, DOGAMI, personal communication, 2000). In 1993, the Mw 5.6 Scotts Mills earthquake occurred about 8 km south of the mapped extent of the Mt. Angel fault (Geomatrix, 1995). It is still unclear whether the earthquake occurred along the Mt. Angel fault. The focal mechanism for the earthquake suggests that the earthquake involved a northwest- striking fault and suggests subequal right- and reverse slip (Geomatrix, 1995). Based on potential historic seismicity, displaced Missoula flood deposits, and a surface scarp in Holocene deposits, we consider the Mt. Angel fault to be active. The maximum surface rupture length ascribed to the fault is 32 km (Wong et al., 2000) which corresponds with a MCE of M 6.8. PI 3.3.8 East Bank Fault The East Bank fault is entirely concealed beneath Quaternary deposits (Madin, 1990) but was previously mapped based on an apparent < 200 m vertical offset of the volcanic basement (Blakely et al., 1995) The present understanding of the fault location has been defined based on the presence of an aeromagnetic signature (Blakely et al., 1995) as well as high - resolution seismic imaging (Pratt et al., 2001) which indicate a substantial lineament parallel to the Portland Hills fault (Blakely et al., 1995). The fault is believed to be a major structural feature because the pronounced aeromagnetic anomaly is consistent with vertical displacements of at least 1 km of the basement volcanic rocks (Blakely et al., 1995). The East Bank fault may serve as a significant component of the eastern margin of the Portland Basin. Pratt et al. (2001) reports that high - resolution seismic imaging indicates that the East Bank fault has had late Pleistocene and ' possibly Holocene activity. This speculation has been supported by recent work performed for the City of Portland Bureau of Environmental Services Combined Sewerage Overflow Project by URS, as well as work completed at the Gunderson Property by other consultants (confidential personal communication, 2001) The data suggest that paleochannels of the Willamette River have been faulted, and that the river channel might be fault controlled. Because of the geophysical evidence available for the East Bank fault, we consider the fault to be active. At its closest projection, the East Bank fault is located about 14.8 km from the school site. The mapped trace of the fault is not well- constrained, however, estimates for the fault length range from 40 to 55 km (Wong et al., 2000), which corresponds with an MCE of M 7.1. URS I 3 -10 I SECTION THREE Seismic hazard Assessment 3.3.9 Oatfield Fault t The Oatfield fault is recognized on the basis of aeromagnetic anomalies and possible association with historic seismicity (Blakely et al., 1995). The fault is located along the western flank of the • Portland Hills and may be structurally associated with the Portland Basin. The school is located 12.6 km west of the Oatfield fault (Figure 5.9). The fault is mapped by Madin (1990) based on water well data, although no definitive surface trace of the fault has been observed. Blakely et al. (1995) suggest that the northern projection of the Oatfield fault may intersect the 1991 swarm of M < 3.5 earthquakes that were also considered to be associated with the Portland Hills fault. As with the Portland Hills fault, the style of deformation of the Oatfield fault is not understood. The associated historical seismicity indicates oblique faulting dominated by right- lateral slip with lesser reverse motion (Blakely et al., 1995). Because of its potential structural and kinematic 1 association with the Portland Hills fault and Portland Basin, and the nearby presence of historical seismicity, we consider the Oatfield fault to be potentially active. The length of the Oatfield fault is not well - known, but best estimates suggest that it may be up to 40 km long (Wong et al., 2000) which corresponds to an MCE of Mw 6.9. 3.3.10 Clackamas River Fault Zone The Clackamas River fault zone includes a series of northwest-trending oblique-slip faults g q P mapped south of Estacada, Oregon along the Clackamas River (Geomatrix, 1995; Hammond et al., 1980; Priest et al., 1983). The maximum length of faults in the zone is 22 km. Faults within the zone have documented right - lateral and normal displacement (Hammond et al., 1980). The faults displace middle Miocene (ca. 15 Ma) Grande Rhonde and Wanapum Basalts. Late Pliocene to early Pleistocene lavas do not appear to be deformed (Priest et al., 1983; Sherrod and Conrey, 1988). A gravel terrace estimated to be approximately 1 Ma crosses the fault and does ' not appear to be displaced (Geomatrix, 1995). Also, no evidence for Quaternary activity was documented during photogeologic analyses for the U.S. Bureau of Reclamation (Geomatrix, 1995). However, the Clackamas River fault has a similar orientation to the Oak Grove - Lake Harriet fault zone to the south and Geomatrix (1995) suggest that there may be a structural association between the two fault zones. Geomatrix (1995) report that some faults within the Oak Grove - Lake Harriet fault zone may have had Quaternary activity. Because of this possible association between the two fault zones, we consider the Clackamas River fault zone to be potentially active. Geomatrix (1995) estimate a maximum surface rupture length of 22 km for the fault zone, which corresponds with an MCE of Mw 6.6. 3.3.11 Grant Butte, Damascus, Tickle Creek Fault Zone Madin (1990) mapped an east - northeast - trending fault within the Portland Basin. A series of randomly oriented faults were mapped in an excavation within Troutdale Formation gravel on Grant Butte and comprise the informally -named Grant Butte fault (Geomatrix, 1995). The ' Damascus - Tickle Creek fault zone displaces Pliocene and possible Pleistocene sediments near Boring, Oregon (Madin, 1990). The northwest - striking fault zone is defined by relatively short (less than 7 km) faults that comprise a zone approximately 17 km long. The combined fault zone is located approximately 16.6 km from the high school. The maximum estimated rupture length URS 3 -11 I SECTION THREE Seismic Hazard Assessment of 17 km reported by Madin (1990) can be used to calculate an MCE of M 6.5. 3.3.12 Other Fault Zones Several faults that are near the school site are discussed below. Based on either a lack of data indicating that these faults are active, or a preponderance of information suggesting that they are not active, we do not include them in the hazard analysis. 3.3.12.1 Sherwood Fault The Sherwood Fault lies approximately 3.0 km south of the school site. Geomatrix (1995) assessed the Sherwood fault for its seismogenic potential and concluded that there was no evidence for Quaternary activity. As part of the 2001 URS South Mist study, aerial photographs were analyzed to evaluate the surface geomorphic character of the fault. The east- northeast- striking fault appears as a highly eroded, north- facing fault line scarp north of Newberg and south of Sherwood. Stream channel gradients do not appear to be affected by the surface scarps. Potential late Pleistocene and possible Holocene deposits that overlie the surface projection of the fault appear undeformed. Based on the conclusions of Geomatrix (1995) and our photogeologic analysis, we do not consider the Sherwood fault to be potentially active. 3.3.12.2 Daily Creek Fault The Dairy Creek fault is a relatively short structure that has been mapped on the basis of subsurface geophysical anomalies (Ian Madin, DOGAMI, personal communication, 2000). There is no evidence for surface expression of the fault, and it does not appear to be structurally or kinematically associated with any nearby faults, and it has not been associated with historic seismicity. Based on a lack of information suggesting potential activity along the fault, we did not consider it in the hazard analysis. 3.3.12.3 Beaverton Fault The west - southwest - striking Beaverton fault is located approximately 11.5 km north of Tigard High School The fault has been located on the basis of geophysical anomalies. No additional information regarding the activity or seismic potential of the fault is currently available, thus we did not consider it in the hazard analysis. 3.3.12.4 Iron Mountain Fault The west - southwest - striking Iron Mountain fault is located approximately 1.5 km south of Tigard High School (Burns et al, 1997). The fault has been located on the basis of geophysical anomalies and well logs. No additional information regarding the activity or seismic potential of the fault is currently available, thus we did not consider it in the hazard analysis. 3.3.13 Cascadia Subduction Zone 1 The megathrust and intraslab region in the subducting Juan de Fuca plate represent two very different seismic sources within the Cascadia subduction zone. Due to the duration and distance effects on ground motion, the megathrust rupture will be considered in this hazard analysis. URS 3 -12 SECTION THREE Seismic Hazard Assessment 3.3.13.1 Megathrust ,! Paleoseismic evidence (e.g., Atwater et al., 1995) and historic tsunami studies (Satake et al., 1996) indicate that the most recent megathrust earthquake in 1700 probably ruptured the full length of the Cascadia subduction zone and was about M 9 in size. Thus, seismic hazard evaluations need to consider future earthquakes of this magnitude, although data cannot preclude the possibility that smaller events have occurred in the past along the megathrust. A significant factor that will control the ground - shaking hazards posed by the Cascadia subduction zone revolves around the location of the megathrust zone. The eastern edge of the megathrust is allowed to vary from about 25 miles offshore to beneath the Coast Ranges with a preferred location beneath the coastline. This results in a source -to -site distance of approximately 120 -km to the site. We adopt a range of maximum magnitudes from M 8 to 9 with the latter given the highest weight. 3.4 REVIEW OF PROBABILISTIC SEISMIC HAZARD ANALYSES Several factors control the level and character of earthquake ground shaking. These factors are in general: (1) rupture dimensions, geometry, and orientation of the causative fault; (2) distance from the causative fault; (3) magnitude of the earthquake; (4) the rate of attenuation of the seismic waves along the propagation path from the source to site; and (5) site factors including the effects of near - surface geology particularly from soils and unconsolidated sediments. Other Pi factors, which vary in their significance depending on specific conditions, include slip distribution along the fault, rupture process, footwall /hanging -wall effects, and the effects of crustal structure such as basin effects. ' In this section, probabilistic analyses have been reviewed to evaluate the ground shaking hazard at the site. This data is being reviewed because insufficient knowledge exists regarding seismic sources in the site region to estimate ground motions associated with the MCE. The literature ' reviewed includes the 1995 Geomatrix Consultants Report Seismic Design Mapping for the State of Oregon produced for the Oregon Department of Transportation, the 2001 URS Probabilistic Study conducted for the South Mist Feeder Pipeline Extension for NW Natural, the Earthquake Hazard Maps assembled for the City of Portland (Wong, 2000), as well as the 1998 Oregon Structural Specialty Code (OSSC). The peak ground accelerations cited in the literature are discussed below. 1 3.4.1 Geomatrix 1995 Probabilistic Study The probabilistic seismic hazard analysis conducted for the 1995 Geomatrix Report produced maps for given design return periods for the State of Oregon. The peak horizontal acceleration experienced at the site for a "500- year" return period on bedrock is approximately 0.19 g. URS I I 3 -1 3 I SECTION THREE Seismic Hazard Assessment 3.4.2 URS /DOGAMI 2000 Portland Metropolitan Study The probabilistic seismic hazard analysis conducted for the 2001 URS Report for the Oregon Department of Geology and Mineral Industries produced maps for given design return periods for the Portland Metropolitan Area (Wong et al, 2000). The peak horizontal acceleration experienced at the site for a "500- year" return period for bedrock is modeled to be 0.20 to 0.25 g as shown on diagram 3 below. iMS - 16 Earthquake Scenario and Probabilistic flround Shaking Maps for the Portland. Oregon, Metropolitan Area by Ivan Wong. Walter Silva. Jacqueline Bott. Douglas Wright. Patricia Thomas. Nick Gregor Sylvia Li, Matthew MabeS Anna Sojourner. and Yumei Wang Probabihty of Exceedance in 50 Years Peak Horizontal A.cceleration (g) at the Ground Surface Po.dc Hortzoutal Acceletalion (g1 Moddfi Iutourtt, I — (from Wall « al lf'C( ) 1 - (t i }(1 \II Very strong aI '':eg.tgable damshag a ge to building,, ofgoud dotage end cormtructo,n slight t, moderate l ;�I� - (I,; ;', :n weu out:[ ord.nnry at, uc'ure., :onstdm ecle ui pwrly buit of designed structures 1 Note The value associated with color key" Fart mm 11 snaps iH', ,\3"C.ii a •wt,b: j '� ^ -r;"^ ,„ }•.'-; ;�% c`. t•°',.- .y „Iw'.e,. w• :q"f�Y %� ".' m om . ko.,, ....'; 4 AAA 3.4.3 1998 OSSC Spectral Ordinates The State of Oregon Structural Specialty Code (OSSC) has adopted the 1997 Uniform Building Code (UBC) including the seismic provisions, with amendments that classify the Oregon Coast south of Newport as Zone 4 due to the recent recognition of the increased ground shaking hazards posed by the Cascadia Subduction zone. The OSSC assigns western Oregon, which includes Tigard High School, to Seismic Zone 3. The seismic coefficient for acceleration for 3 -14 I SECTION THREE Seismic Hazard Assessment Zone 3 is 0.30. The site soil profile can be best classified as a Stiff Soil Profile (SD) with average weighted SPT N- values ranging between 15 and 50 blows per foot. Table 1. OSSC 1998 Seismic Values Parameter Value 1997 UBC Reference Soil Profile SD Table 16 -J Seismic Zone 3 Figure 16 -2 Zone Factor, Z 0.3 Table 16 -I Seismic Source Type C Table 16 -U Near Source Factor N 1.0 Table 16 -S Near Source Factor N 1.0 Table 16 -T Seismic Coefficient C 0.36 Table 16 -Q ' Seismic Coefficient C 0.54 Table 16 -R • 3.4.4 Site Specific Response Spectrum URS has prepared a elastic design response spectrum for the site with a 5% damping ratio in accordance with Section 1631.2.2 of the 1998 OSSC at the client's request. This response spectrum was generated using the geologic, tectonic, seismologic, and subsurface soil conditions particular to the Tigard High School Site in conjunction with a suite of earthquakes with similar magnitudes and /or site -to- source distances selected to provide a similar peak ground acceleration as that recommended by the URS (2001) and Geomatrix (1995) Reports. This suite of earthquakes was propagated through the shear wave column (provided by CPT data) ' in the computer program SHAKE2000 (Ameritech Engineering, 2000), a front -end module that utilizes SHAKE91 to analyze the earthquake response from a series of 1- Dimensional, horizontally layered media to produce site response at the ground surface for 6 modeled earthquake events. Of these 5 events, 3 were near -field strike -slip or oblique -slip fault events, and the last two were subduction motion as shown below in Table 2. The responses for these 5 events are shown on Figure 4 Design Earthquake Suite, and were averaged to produce the URS 2004 Design Spectrum (Shown in Red on Figure 4 & 5). I 1 UR S 3 -15 I SECTION THREE Seismic Hazard Assessment I Table 2. Selected Earthquakes for Spectral Analyses I Type Earthquake Name Magnitude Fault T e Peak Ground Site to Source q 9 (M Acceleration (PGA) Distance (km) 2002 URS Cascadia 9.0 Subduction 0.23 g 120 km I Synthetic Interplate 1968 Tokachi -Oki Event, 7.9 Subduction 0.31 g 186 km I Hachinohe N_S Record Interplate 2002 URS 10% in 50 Year 6.8 Crustal 0.23 g 10 km I Spectral Match Loma Prieta Earthquake, 7.0 Oblique -Slip 0.23 g 15.6 km I Gilroy #7 Array 000 motion San Fernando Earthquake, 6.5 Oblique -Slip 0.26 g 23.5 km I Castaic Old Ridge 291 Record s pit 3.4.5 Results Comparison As described in Section 4.3, Probabilistic Seismic Hazard Analysis, URS conducted a site - I specific study to assess ground accelerations with a 10% probability of exceedance in 50 years in accordance with OSSC 1804.5. The probabilistic study conducted for this project indicates that the site would be subject to peak ground accelerations of 0.20g within this return period. I Although this value is lower than values published in the literature, this modeling effort incorporated the most up -to -date seismic source data for the greater Portland area. A comparison I of these values is shown in Table 4 below. The probabilistic seismic hazard analyses reviewed above are compared in Table 1 below. I Table 3: Comparison of Peak Ground Accelerations for Hazard Modeling Portland • 1995 Geomatrix Metropolitan "500" year event OSSC 1998 "500" Results of Site - Specific Response year � Reference "500" year event ear event (C for S p ectra generated for site for suite Site SD of earthquake motions (Wong et al, 2000) 1 Peak Ground Acceleration 0.19g 0.20 — 0.25g 0.36g 0.20g (gravity) I 3.5 I URNS 3 -16 I 1 SECTION THREE Seismic Hazard Assessment 3.6 RECOMMENDED DESIGN GROUND MOTIONS As shown on the 2004 URS Design Spectrum (Figure 5) the site - specific response spectrum projects spectral accelerations considerably lower than those mandated by the 1998 OSSC design spectrum. It is URS opinion that application of the 2004 URS Design Spectrum would be appropriate at this site. As the spectral responses calculated by URS are lower than the OSSC response spectrum envelope, URS recommends that the design base shear calculated for the structure be reduced to 80% of the standard code base -shear per Section 1631.5.4.2 of the 1998 OSSC. 3.7 SEISMIC HAZARDS Liquefaction is the drastic loss of soil strength that can accompany ground shaking during a moderate to strong seismic event. During ground shaking, cyclic earthquake loading on the soil increases pore water pressure to a point where the effective stress on the soil is zero or even negative, resulting in suspension of soil particles in the water. Loose, granular soils located below the water table are generally susceptible to liquefaction. Soils are initially screened for liquefaction potential in their composition by comparing ' laboratory- tested properties against the "Chinese Criteria" (Wang, 1979). These criteria set thresholds for the moisture content, liquidity index, liquid limit, and fines content that have been found to be common in observed liquefied soils. If the Chinese criteria are satisfied, or if laboratory samples to satisfy these tests are not possible, then the soil is termed "potentially liquefiable" pending advanced laboratory testing or field work. The potentially liquefiable soil zones are then subjected to quantitative trigger analyses that are implemented based on the pre- 1111 earthquake densities and characteristics of observed liquefaction deposits in nature. SPT -based trigger analyses were conducted using the "Simplified Procedure" developed in 1971 by Seed and Idriss, and subsequently modified and updated to incorporate advances in the ' understanding of liquefaction trigger- mechanisms and other data. Since the inception of this analysis method, several large earthquakes have occurred that have produced large liquefaction data sets as well as new observations concerning free -field liquefaction behavior (e.g. M = 6.7 Northridge event, M = 7.0 Loma Prieta event, M = 7.2 Hyogoken -Nanbu (Kobe) event etc.). Since 1996, researchers in the field have convened in an effort to update the Simplified ' Procedure in light of the data from these large earthquakes. The published recommendations from these workshops have been incorporated into the URS assessments of the subject site (Youd et al, 2001). Generally speaking, the Simplified Procedure takes the borehole sample data, and converts the field N- values into an equivalent N -value in clean sand at 60% normalized hammer efficiency with appropriate modifications made for fines content, relative density, etc. The N -value is then converted into an equivalent critical resistance ratio (CRR) against liquefaction, and compared to the critical stress ratio (CSR) generated by multiple cycles of the design earthquake event. The factor of safety is the ratio of the equivalent resistance divided by the design critical stress ratios for that depth. Factors of safety lower than 1.0 indicate a propensity for similar soils to liquefy under those earthquake loading conditions, resulting in the classification of "liquefiable" for the soils at that depth. Factors of safety between 1.0 to 1.3 generally indicate a marginal ability to resist liquefaction when subjected to the earthquake load input in the Simplified Procedure. URS 3 -17 I SECTION THREE Seismic Hazard Assessment 1 The state -of -the -art approach to liquefaction analyses has shifted away from the Simplified Procedure approach outlined above and towards the use of site - specific response analyses to directly calculate the in -situ CSR within the subsurface strata for a suite of earthquake groundmotions (Seed et al, 2003). This approach has been employed within this report by using 1 the critical stress ratios developed by each event within the suite of design earthquakes processed by SHAKE2000 compared to the CRR developed from the CPT logs. ' However, it should be noted that liquefaction alone does not pose a risk to soil deposits. It is the phenomena accompanying liquefaction can severely damage structures situated in or on the soil. This includes settlement, lateral spreading, flow failures, and bearing capacity failure, which are individually discussed in the following sections. 3.7.1 Liquefaction Hazard The site - specific Cyclic Stress Ratio Response Approach (seed et al, 2003) indicates that no strata within the upper 50 feet of the site should liquefy in a design earthquake (CRR/CSRDesi I site > 1.0 for 80% of the suite, with values dropping down to 90% for the Tokachi -Oki Event). This indicates that liquefaction will not likely occur at this site, and that the risk of liquefaction is low overall. ' 3.7.1.1 Seismically Induced Settlement Following a seismic event, the excess pore water pressure tends to dissipate, resulting in a rearrangement of the soil particles into denser packing. This densified rearrangement of the liquefied soils is a common method by which settlement of the ground surface is induced. ' Another mechanism that induces settlement is the generation of sand boils during and after earthquake events. Severe ground motions can cause such extreme pore water pressure that a negative effective stress (a pressure buildup in the liquefied layer) is induced. The soil relieves this pressure by ejecting groundwater to the ground surface, carrying with it fine sands and silts. These features are known as sand boils, and they typically result in a reduction in the volume of soils from the liquefied layer, a phenomenon that is accompanied by vertical settlement at the ' ground surface as this void collapses and the soils rearrange themselves into a denser packing. It is URS opinion that seismically induced settlement at this sit is not a risk due to the generally ' high blow counts across the site. 3.7.1.2 Lateral Spreading Hazard It is URS opinion that lateral spreading at this site is not a risk due to generally level topography at the site. ' 3.7.1.3 Bearing Capacity Failure As described above, ground shaking can induce cyclic earthquake loading on the soil that increases pore water pressure to a point where the effective stress on the soil approaches zero, resulting in buoyant forces that suspend of soil particles in the water. At the point where the effective stress reaches zero, the soil no longer retains the ability to resist vertical loading, and structures may sink or topple on mat foundations, until equilibrium is reestablished. The risk of URS 3 -18 SECTION THREE Seismic Hazard Assessment r bearing capacity failure across the site is low based upon the estimated thickness of compacted ' fill that will be placed below the buildings during construction. It is our opinion that these compacted soils will prevent a loss of bearing capacity by dispersing the structural loads across the compacted fill. 1111 As no liquefaction is anticipated in the upper 30 feet of soils, no bearing capacity failre is expected to manifest during ground shaking. 3.7.2 Tsunami /Seiche Hazard ' URS understands that this site is not located near any body of water that is susceptible to tsunami or seiche. Therefore, it is URS opinion that Tsunami or Seiche hazard at this site does not exist. 3.7.3 Seismic Slope Stability Hazard As discussed above, URS understands that no cuts or fills are planned that would alter the ' generally level topography on the site. Therefore, it is URS opinion that hazards from seismic failure of slopes at this site does not exist. 3.7.4 Surface Rupture Hazard Review of available geologic mapping indicates that no known fault trace passes beneath the proposed facility. Therefore, it is URS opinion that hazards from ground rupture at this site does not exist. ' 3.7.5 Ground Shaking Amplification Hazard It is URS opinion that the generally dense nature of the soil column will not lead to amplification of groundmotions as they propagate through the basin. URS 1 I I 3 -19 SECTION THREE Seismic Hazard Assessment ' Ameritech Engineering , Ordonez- Comparini, Gustavo A., 2000, SHAKE2000, A Computer Program for the 1 -D Analysis of Geotechnical Earthquake Engineering Problems. (t Atwater, B.F., Nelson, A.R., Clague, J.J., Carver, G.A., Yamaguchi, D.K., Bobrowsky, P.T., Bourgeois, J., Darienzo, M.E., Grant, W.C., Hemphill - Haley, E., Kelsey, H.M. Jacoby, G.C., Nishenko, S.P., Palmer, S.P., Peterson, C.D., and Reinhart, M.A., 1995, Summary of coastal geologic evidence ' for past great earthquakes at the Cascadia subduction zone: Earthquake Spectra, v. 11, p. 1 -18. Bakun, W. H., 2000, Seismicity of California's North Coast: Bulletin of the Seismological Society of America (in press). ' Beeson, M.H., Fecht, K.R., Reidel, S.P., and Tolan, T.L., 1985, Regional correlations within the Frenchman Springs Member of the Columbia River Basalt Group: New insights into the middle Miocene tectonics of northwestern Oregon: Oregon Geology, v. 47, p. 87 -96. ' Beeson, M.H., Tolan, T.L., and Anderson, J.L., 1989, The Columbia River Basalt Group in western Oregon; geologic structures and other factors that controlled flow emplacement patterns: Geological Society of America Special Paper 239, p. 223 -246. Blakely, R.J., Wells., R.E., Yelin, T.S., Madin, I.P., and Beeson, M.H., 1995, "Tectonic Setting of the Portland - Vancouver area, Oregon And Washington: Constraints From Low - Altitude Aeromagnetic Data ", Geological Society of America Bulletin 107, p. 1051 -1062. Bott, J.D.J. and Wong, I.G., 1993, Historical earthquakes in and around Portland, Oregon: Oregon Geology, v. 55, p. 116 -122. Burns, S., Gowney, L., Broderson, B., Yeats, R.S., and Popwski, T.A., 1997, Map showing faults, bedrock geology, and sediment thickness of the western half of the Oregon City 1:100,000 ' quadrangle, Washington, Multnomah, Clackamas, and Marion Counties, Oregon, Oregon Department of Geology and Mineral Industries, Interpretive Map Series IMS -4. Geomatrix Consultants, Inc., 1995, "Seismic Design Mapping State of Oregon: Final Report ", prepared for the Oregon Department of Transportation, Contract 11688. Hammond, P.E., Anderson, J.L., and Manning, K.J., 1980, Guide to the geology of the Upper Clackamas and North Santiam Rivers area, northern Oregon Cascade Range, in Oles, K.F., Johnson, J.G., ' Niem, A.R., and Niem, W.A. (eds.), Geologic Field Trips in Western Oregon and Southwestern Washington: Oregon Department of Geology and Mineral Industries Bulletin 101, p. 133 -167. ' Hart, D.H., and Newcomb, R.C., 1965, Geology and groundwater of the Tualatin Valley, Oregon. U.S. Geological Survey Water - Supply Paper 1697 Hemphill - Haley, M., Liberty, L.M., and Madin, I.P., 2002, Source Characterization Study of the Portland Hills Fault, Portland Metropolitan Area, Oregon, Volume Final Report for National Earthquake Hazards Reduction Program, Award Number 00HQR0023, 16 pages. ' Johnson, S.Y., Dadisman, S.V., Childs, J.R., and Stanley, W.D., 1999, Active tectonics of the Seattle fault and central Puget Sound, Washington — Implications for earthquake hazards: Geological Society of America Bulletin, v. 111, p. 1042 -1053. ' Liberty, L.M., Trehu, A.M., Dougherty, M.D., and Blakely, R.J., 1996, High - resolution seismic - reflection imaging of the Mt. Angel /Gales Creek fault system beneath the Willamette Valley: EOS, Transactions of the American Geophysical Union, v. 77, p. 655. URS I 3 -20 SECTION THREE Seismic Hazard Assessment r Ludwin, R.S., Weaver, C.S., and Crosson, R.S., 1991, Seismicity of Washington and Oregon, in Neotectonics of North America, D.B. Slemmons, E.R. Engdahl, M.D. Zoback, and D.D. Blackwell (eds.): Geological Society of America Decade Map, v. 1, p. 77 -98. Madin, I.P., 1990, Earthquake Hazard Geology Maps of the Portland Metropolitan area, Oregon, Oregon Department of Geology and Mineral Industries, Open File Report 0 -90 -2, Beaverton Quadrangle. Madin, I.P., and Hemphill- Haley, M.A., 2001, The Portland Hills fault at Rowe Middle School (new ' evidence), Oregon Geology, v. 63, p. 47 -49. Magill, J.R., Wells, R.E., Simpson, R.W., and Cox, A.V., 1982, Post -12 m.y. rotation of southwest r Washington: Journal of Geophysical Research, v. 87, p. 3761 -3776. Malone, S. D. and Bor, S. S., 1979, Attenuation patterns in the Pacific Northwest based on intensity data and the location of the 1872 North Cascades earthquake: Bulletin of the Seismological Society ' of America, v. 69, p. 531 -546. McCaffrey, R., 1994, Global variability in subduction thrust zone -fore arc systems: Pure and Applied Geophysics, v. 142, p. 173 -224. ' Niewendorp, C.A., and Neuhaus, M.E., 2002, Map of Selected Earthquakes for Oregon, 1841 through 2002, Oregon Department of Geology and Mineral Industries, Open File Report 0- 03 -02. 'r Orr, E.L., Orr, W.N., and Baldwin, E.M., 1992, Geology of Oregon, Kendall /Hunt Publishing Co., Dubuque, Iowa, 4` Edition, p. 203. PI Pezzopane, S.K., 1993, Active Faults and Earthquake Ground Motions in Oregon, Ph.D. Thesis, University of Oregon, 208 p. Phillips, W.M., 1987, Geologic map of the Vancouver quadrangle, Washington and Oregon: Washington Division of Geology and Earth Resources Open -file Report 87 -10, 1:100,000. Pratt, T.L, Odum, J., Stephenson, W., Williams, R., Dadisman, S., Holmes, M., and Haug, B., 2001, "High- Resolution Seismic Images of the Late Pleistocene Unconformity, Ancestral Columbia r River and Holocene Faulting Beneath the Portland- Vancouver Urban Area, Oregon and Washington ", Bulletin of the Seismological Society of America, v. 91, p. 637 -650. r Priest, G.R., Woller, N.M., Black, G.L., and Evans, S.H., 1983, Overview of the geology of the central Oregon Cascade Range, Chapter 2, in Priest, G.R., and Vogt, B.F. (eds.), Geology and Geothermal Resources of the Central Oregon Cascade Range: Oregon Department of Geology and Mineral Industries Special Paper 15, p. 3 -28. Satake, K., Shimazaki, K., Tsuji, Y., and Ueda, K., 1996, Time and size of a giant earthquake in Cascadia inferred from Japanese tsunami records of January 1700: Nature, v. 379, p. 246 -249. r Schlicker, H.G., and Deacon, R.J., 1967, Engineering geology of the Tualatin Valley Region, Oregon: Oregon Department of Geology and Mineral Industries Bulletin 60 Seed, H.B., and Idriss, LM., 1971. "Simplified Procedure for Evaluating Soil Liquefaction Potential", Journal of Geotechnical Engineering, ASCE, New York, 41 -64. Seed, R.B., Cetin, K.O., Moss, R.E.S., Kammerer, A.M., Wu, J., Pestana, J.M., Riemer, M.F., Sancio, R.B., Bray, J.D., Kaynen, R.E., and Faris, A., 2003, Recent Advances in Soil Liquefaction Engineering: A Unified and Consistent Framework, Keynote Presentation, 26 Annual ASCE Los Angeles Geotechnical Spring Seminar, April 30, 2003, 71 pages. r URS 3 -21 r I� SECTION THREE Seismic Hazard Assessment 1 Sherrod, D.R. and Conrey, R.M., 1988, Geologic setting of the Breitenbush- Austin Hot Springs area, Cascade Range, north- central Oregon, in Sherrod, D.R. (ed.), Geology and Geothermal Resources of the Breitenbush- Austin Hot Springs Area, Clackamas and Marion Counties, Oregon: Oregon Department of Geology and Mineral Industries Open -File Report 0 -88 -5, p. 1- l• 14. Stanley, W.D., Johnson, S.Y., Qamar, A.I., Weaver, C.S., and Williams, J.M., 1996, Tectonics and seismicity of the southern Washington Cascade Range: Bulletin of the Seismological Society of ' America, v. 86, p. 1 -18. Stover, C.W. and Coffman, J.L., 1993, Seismicity of the United States, 1568 -1989 (Revised):U.S. ' Geological Survey Professional Paper 1527, 415 p. Thomas, G. C., Crosson, R. S., Carver, D. L., and Yelin, T. S., 1996, The 25 March 1993 Scotts Mills, Oregon earthquake and aftershock sequence: Spatial distribution, focal mechanisms, and the Mount Angel fault: Bulletin of the Seismological Society of America, v. 86, p. 925 -935. Thorsen, G.W. (editor), 1986, The Puget Lowland earthquakes of 1949 and 1965: Washington Division of Geology and Earth Resources, Information Circular 81, 113 p. Toppozada, T. R., Real, C. R., and Parke, D. L., 1981, Preparation of isoseismal maps and summaries of reported effects for pre -1900 California earthquakes: California Division of Mines and Geology Open File Report 81 -11, 181 p. Trimble, D.E., 1963, Geology of Portland, Oregon, and adjacent areas: U.S. Geological Survey Bulletin 1119 Unruh, J.R., Wong, I.G., Bott, J.D.J., Silva, W.J., and Lettis, W.R., 1994, Seismotectonic Evaluation. Scoggins Dam, Tualatin Project, Northwestern Oregon; William Lettis & Associates and Woodward -Clyde Federal Services, unpublished final report prepared for the U.S. Bureau of Reclamation, Denver, CO. URS, 2001. "Appendix H -1, Geological and Seismic Hazard Evaluation — South Mist Feeder Extension Project, Phases IV and V ". Prepared for NW Natural, URS Job No. 52- 00082007 in support of the EFSEC Application USGS, 2004, Felt IntensityCommunity Internet Intensity Map, Event No. 2281854, USGS Nisqually Earthquake Clearinghouse Website, http: // maximus .ce.washington.edu /— nisqually /seis/ - observations.html Wald, D.J., Quitoriano, V., Heaton, T.H., and Kanomori, H., 1999, Relationships between peak ground acceleration, peak ground velocity, and Modified Mercalli intensity in California: Earthquake Spectra, v. 15, p. 557 -564. Wang, W., 1979, Some findings in soil liquefaction, Water Conservancy and Hydroelectric Power Scientific Research Institute, Beijing, China. Weaver, C.S. and Smith, S.W., 1983, Regional tectonic and earthquake hazard implications of a crustal ' fault zone in southwestern Washington: Journal of Geophysical Research, v. 88, p. 10,371- 10,383. Wells, D. and Coppersmith, K.J., 1994, New earthquake magnitude and fault rupture parameters, ' Correlations among earthquake magnitude, rupture length, and fault displacement: Bulletin of the Seismological Society of America, v. 84, p. 974 -1002. Wells, R.E., Weaver, C.S., and Blakely, R.J., 1998, Forearc migration in Cascadia and its neotectonic * � significance: Geology, v. 26, p. 759 -762. URS 3 -22 1 `I SECTION THREE Seismic Hazard Assessment 1 Wilson, Doyle, 1997, Post - middle Miocene geologic history of the Tualatin basin, Oregon with ' hydrogeologic implications, Portland State University Masters Thesis Abstract, http: / /nwdata.geol.pdx.edu /Thesis /Abstract.php ?Th_ID =127 Wong, I.G., 1997, The historical earthquake record in the Pacific Northwest: Applications and (1 implications to seismic hazard assessment, in Earthquakes -- Converging at Cascadia, Symposium Proceedings, M. Wang and K. Neuendorf (eds.), Association of Engineering Geologists Special Publication 10 and Oregon Department of Geology and Mineral Industries Special Paper 28, p. ' 19 -36. Wong, I.G. and Bott, J.D.J., 1995, A look back at Oregon's earthquake history, 1981 -1994: Oregon ' Geology, v.57, p. 125 -139. Wong, I.G. and Silva, W.J., 1998, Earthquake ground shaking hazards in the Portland and Seattle metropolitan areas, in Geotechnical Earthquake Engineering and Soil Dynamics III, P. Dakoulas, ' M. Yegian, and R.D. Holtz (eds.): American Society of Civil Engineers Geotechnical Special Publication No. 75, v. 1, p. 66 -78. Wong, I., Silva, W., Bott, J., Wright, D., Thomas, P., Gregor, N., Li, S., Mabey, M., Sojourner, A., and Wang, Y., 2000, Earthquake scenario and probabilistic ground shaking maps for the Portland, Oregon, Metropolitan Area: Oregon Department of Geology and Mineral Industries Interpretative Map Series IMS -16, scale 1:62,500, 11 sheets with 16 p. text. Wong, I.G., Pezzopane, S.K., and Blakely, R., 1999, A characterization of seismic sources in western Washington and northwestern Oregon (abs.): Seismological Research Letters, v. 70, p. 221. PI Wong, I.G., Hemphill - Haley, M.A., Liberty, L.M., and Madin, I.P., 2001, The Portland Hills fault: An earthquake generator or just another old fault ?, Oregon Geology v. 63, p. 39 -50. Woodward -Clyde Consultants, 1992, Seismic hazard evaluation for South Fork Tolt Dam and Regulating ' Basin, unpublished final report prepared for Seattle Water Department. Yeats, R.S., Graven, K., Werner, C., Goldfinger, C., and Popowsky, T., 1991, Tectonics of the Willamette Valley, Oregon; U.S. Geological Survey Open -File Report, 91- 441 -P, 47 p. Yelin, T.S., and Patton, H.J., 1991, Seismotectonics of the Portland, Oregon region, Bulletin of the Seimological Society of America, v. 81, p. 109 -130. ' Youd, T.L., Idriss, I.M., Andrus, R.D., Arango, I., Castro, G., Christian, J.T., Dobry, R., Finn, W.D.L., Harder, Jr., L.F., Hynes, M.E., Ishihara, K., Koester, J.P., Liao, S.S.C., Marcuson III, W.F., Martin, G.R., Mitchell, J.K., Moriwaki, Y., Power, M.S., Robertson, P.K., Seed, R.B., and ' Stokoe 1I, K.H., 2001. "Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils ", ASCE Journal of Geotechnical and Geoenvironmental Engineering, Vol. 127, No. 10, pp. 817 -833. I URS 3 -23 I N — r B -02 -2003 I 11 W — E ` i , i _r \ O CPT -01 -2003 i i j f 1 Iii 1 , • l - 0 I 1 r------ y I I It B e ' 1 -- - i r C PT -02 -2003 I I I ___ ..„._. (0* ,,\ \_. • +, I I L __ h 1 rx I I I 1 • • _, . O ;/ I I o �— .,\ i_ _ - B -01 - 2003 ° L___,,,___, I °° 0 0 a o 0 , , + . \ ° 8-03 -2003 - - cm 1 O - - - - I O LEGEND: 4- B -01 -2003 URS BOREHOLE LOCATION, DECEMBER 2003 I CPT-01-2003 URS CONE LOCATION, 0 DECEMBER 2003 1 \ \ , - ao 120 O 1 40 1--1 la I 15 I SCALE IN FEET I, DRAWING NUMBER: JOB No. DESIGNED. PROD. ENGINEER: TIGARD- TUALATIN SCHOOL URS 25895580 JOD TJR APPROVED WARNING CAD FILE NUMBER: TIGARD HIGH SCHOOL FIGURE 1 I _ _ o DISTRICT SCALE: DRAWN BY VED BY: JOD BM IF BAR DOES NOT 111 SW Columbia, Suite 900 BOREHOLE LOCATION MAP 01 Portland, Oregon 97201-5814 6960 SW SANDBURG ST ,• MEASURE E ,' AT FULL SIZE, THEN SCALES TIGARD, OREGON CHECKED BY: DATE: ON DRAWING NOT (tel) 503-222-7200 SHEET: REV. TJR 1/28/04 TO SCALE. (fax)503-222 -429z TIGARD, OREGON 97223 1 OF 1 A No. DATE BY REVISION WWW.IltSCAfP.COfn 1 I The intensity of an earthquake is a measure of the amount of ground shaking at a particular site, and it is determined from reports of human reaction to shaking, damage done to structures, and other effects. The Modified Mercalli Scale I is commonly used to rank the intensity from Ito XII according to the kind and amount of damage produced. I. Not felt except by a very few under especially favorable circumstances. II. Felt only by a few persons at rest, especially on upper floors of buildings. Delicately suspended objects may swing. III Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibration similar to the passing of truck. Duration estimated. IV. Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably. V. Felt by nearly everyone; many awakened. Some dishes, windows broken. unstable objects overturned. Pendulum clocks may stop. ' VI. Felt by all; many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight. VII Damage negligible in building of good design and construction; slight to moderate in well -built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. Noticed by persons driving motor cars. 01 VIII Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned. IX. Damage considerable in specially designed structures; well - designed ' frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations. X. Some well -built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rails bent. XI. Few, if any (masonry) structures remain standing. Bridges destroyed. Rails bent greatly. XII. Damage total. Lines of sight and level distorted. Objects thrown into the air. From: Noson, Qamar, and Thorsen, Washington State Earthquake Hazards, 1988, Washington Division of Geology and Earth Resources Information Circular 85 I IR 1f I MODIFIED MERCALLI INTENSITY (MMI) SCALE DESCRIPTION IURS SEISMIC HAZARD REPORT January 2004 TIGARD HIGH SCHOOL REMODEL 25695560.10001 Tigard, Oregon I FIGURE 2 1 „_......... ., . R`{'g Ji L {s' ` .. /`» 9� Y ' - \ a .$. \\� 00040ra110410 , , - m q !:° .:•7 4 .: ' _• � .�i fit, - '- -ter - -- - - - -_. _ - - -- - - w' is 1, F }r F o IL "ate , •> • x .J • ` - 0' ;°`, nn.4'tht . • _ al CiN .LIAM 0.10.8 Y + - , SHE.RMA4 • v • ( • MORROW! 00.'1 .YMu , : 0 , • • • ,.• b Ilk, • SITE j . : ..� .,. • a • •- •. • • A•A •M;Nv ivMf Fi FR ` • G,rvlp W . ryy • GRAM' O . • `O a ION • ^ Y•., tit.h ..M .• • •' • y, • s,Cy • . • • • . . * • CROON t • ,AME • • - DE SL: F. ft'S ® I , ,t' a • i 0 • - • Myw.rt wl009. NANt(r" .. • GiVWM •ieYba '.* • _ • M••:44*50 -Y.9 1 t•.. .., _ ,.A. . • Nw 5.11.SY -+l M••ru•et.Y -•Y , 54•••6 J.V -S.Y I - • M••wuJU t ➢ -2.Y N • • • lr.l Iw•rne j " •gwW,F•oa • tl • `•iF • • 9L•Mtl•Il / • I_ I rtl • pvM Q. .• " • G I SOURCE: ,, , OREGON MAP OF HISTORICAL EARTHQUAKES, 1841 -2002 i NIEWENDROP, C.A. & NEUHAUS, M.E. 2003 MAP OF SELECTED EARTHQUAKES FOR OREGON, 1841 THROUGH 2002, TIGARD HIGH SCHOOL REMODEL g URS OREGON DEPARTMENT OF GEOLOGY & MINREAL INDUSTRIES, JANUARY 2004 SEISMIC HAZARD REPORT OPEN FILE REPORT OFR- 03 -02. 25695560.10001 TIGARD, OREGON FIGURE 3 I I I 1 r Earthquake Suite for Tigard High School 0.8 i i 1 I I M =9.0 URS Synthetic Cascadia Subduction Event I - 10% in 50 Year URS Synthetic Spectral Match Event 0.6- _ ,' - M =8.2 Tokachi -Oki 1968 I 0 Subduction Event, Hachinohe i ` ( N -S Record L 1 y , e 1 M =7.2 Loma Prieta 1989 Event, v ' Gilroy Array #7 000 Record a I 0.4- - M =6.5 San Fernando 1971 ) I + Event, Castaic Old Ridge " - - Route 291 Record Q _ Average Sa for 5% Damping - I 1 f Tigard High School - _ - ilk 1 0.001 0.01 0.1 1 10 I Period (sec) I I I Note: PREPARED IN ACCORDANCE WITH OSSC (1998)- 1804.5 I DESIGN EARTHQUAKE SUITE I SITE- SPECIFIC SEISMIC HAZARD REPORT URS PROJECT TTSD TIGARD HIGH SCHOOL REMODEL JANUARY 2004 TIGARD, OREGON I FIGURE 4 I I I I 10% in 50 Year Design Response Spectrum _ ■ Design Response Spectrum for 5% damping - Tigard High I 013 - _ School a) • UBC 1997 - Zone 3 - c Soil Sd co d 0.6- - V 1 U Q To ll 0.4- - 111 co IIII 0.2- - i 0 . 0 � I , f I I I T I I P I 1 I - 0.001 0.01 0.1 1 10 I Period (sec) I I I Note: PREPARED IN ACCORDANCE WITH OSSC (1998)- 1804.5 I 2004 URS DESIGN SPECTRUM I SITE - SPECIFIC SEISMIC HAZARD REPORT M S URS PROJECT TTSD TIGARD HIGH SCHOOL REMODEL _ JANUARY 2004 TIGARD, OREGON I FIGURE 5 I Jr ‹ Z MN IMO NM MN NM MI MI MN MN A gm EMI MI • MI MIN MEI NM I STATE ENGiREER Salem, Oregon WA S H ...2.. Well Record STATE WELL NO. a.) /5‘,10 COUNTY GfitZSA.1:12/..Z.42,>/. 011707 .....—" APPLICATION NO. I 4a1,04.11,...* ........ , MAILING OWNER: — if rit4.14 Sa.7_,i_ar 1--litit ahrx.f. ADDRESS: CITY AND --- - • is LOCATION OF WELL: Owner's No. STATE: N. E. . , 1 /4 3 /4 Sec. T. S., R. W., W.M. ! ■ 1 i Bearing and distance from section or subdivision , II corner : , 1 i ! . I 1 I ; i I ) Altitude at well .1.9.0.J:e ! 1 i TYPE OF WELL: _cte:ili_t_i Date Constructed i i _, I Depth drilled .i.zo 1.2 in Depth cased 6(. ik: Section CASING RECORD: , I I FINISH: IIII AQUIFERS: — /3 -- 67 .4, 9 1 WATER LEVEL: 7 --- /'4 be/dta /a >7 cj 5 cc. i- e c_. • - - I ) PUMPING EQUIPMENT: Type .. ritl- - .17_2.k_e_ H.P. Capacity G.P.M. I WELL TESTS: Drawdown ft. after hours G.P.M. Drawdown ft. after hours G.P.M. I USE OF WATER i g_k_b_t/C... 5 ccta,ely Temp. °F. ,19 SOURCE OF INFORMATION )1, G. .5 DRILLER or DIGGER I ADDITIONAL DATA: Log ..y Water Level Measurements Chemical Analysis Aquifer Test REMARKS: s , e e. .. k/, ,,z 74,. 47. I I I State Printing 89316 I I STATE ENGINEER State Well No. ..2s/n.0 MAO_ I Salem, Oregon County Wa *‘.-- Application No. ->, I Well Log Owner: 72qcti-c( Se}i: or Hipt Sqlt_o_al Owner's No. I Driller: Ste-1.n >1.7..Oni Ten-.5., 1?1"; C ?.. .0, Date Drilled (Feet below end surface) Thickness -- CHARACTER OF MATERIAL i .. From To (feet) — — Valle.) f'71! I , _ / y,.///)&a 1— II , ,b4u..p ( ,. 1- II "rQuJrkca.)74 ' .1fO 4 II , ic.- - ______Z 1111 _ 5 d ._ 111. _. • _ C.. (el , Wu. - 71 - ea y _..a_6f2 s...1104 i 14/al efr loecti-,`i4 7 -1.4.1 / 1 cky , 1,1k, e. - 7 )-cty 1g I /, ) illa-e- ..__.,6"» 9 " brow n ) _g‘o id I - .47/ /7 (e,,' blue-yray I (' _Icky ) i 1 I ut.e__ " , 7 I hrow) .<47 _ 0 tii.' 1 h mit*, umbel in orate elk) Wecithei-ed 7frtivel Z/z/,..3 ,f I _ ft _ ) blme_ - 7ray I ) br,,wh licr-i'ff 1 /7f ....2, I , c -,,, k 0 c,o iect e- "- b ro w I 1 (p T e 2 STATE ENGINEER State Well No. 2 /r/1(/�.. I Salem, Oregon County 1A1_Q s4. Application No. Well Log I Owner: 11 ' .__._Se.h.;_Qr /4('7.,k 5eSao( Owner's No. 1 Driller: Date Drilled • CHARACTER OF MALsltIAT. (Feet below land surface) Thickness 1 From To _ (feet) ( lo It e < , s yid y ,.5� $ .3 I. " / ( ' h q r 0 27.677 ul )p O r , Glaf/ , re ci 6.x`1 zl _ ( /'a e'ilc ' r .44 s a h' : Nir I dc, 7 ,00(Z', , C(c,V y P c( _3 3/ y . /(o,e.) 127 .''7 It , „ • , L.0 6027 )4.14060 (p.'y ut aU 'z ) - !(� 9-0 „z. I t15 q 1p J /L, e 4'5-7 T Oil 7 e?,,,.e„______,b,-„,,,, I /lo o./t j b/a c ' k CO5 /.5 _ I , 1 , I . 1 I _ I 1- I I Project: Tigard High School Key to Log of Boring Project Location: Durham, Oregon Project N umber: 25695560.10001 Sheet SAMPLES N C O O o a) ° a) 0 MATERIAL DESCRIPTION E)3 REMARKS AND w w o a' a E E ( o 8 a i_ OTHER TESTS m z in � in � 0 oN 1 2 © 4 5 6 7 8 9 10 i COLUMN DESCRIPTIONS 1 Elevation: Elevation in feet referenced to mean sea level 7 Graphic Log: Graphic depiction of subsurface material I (MSL) or site datum encountered, typical symbols are explained below. 2 Depth: Depth in feet below the ground surface. 18 Material Description: Description of material encountered, may include color, moisture, grain size, and density /consistency 3 Sample Type: Type of soil sample collected at depth interval I shown, sampler symbols are explained below. 4 Sample Number: Sample identification number 9 Drill Time: Time (recorded in 24 -hour clock) of sampling or other events during downhole advance. 10 Remarks and Other Tests: Comments and observations 5 Blows per 6 inches: Number of blows required to advance regarding drilling or sampling made by driller or field personnel driven sampler each 6 -inch drive interval, or distance noted, Other field and laboratory test results, using the following using a 140 -lb hammer with a 30 -inch drop (unless otherwise abbreviations. stated). 6 Recovery: Percentage of driven sample length (or penetration distance) actually recovered. I • TYPICAL MATERIAL GRAPHIC SYMBOLS Asphaltic Concrete . oncrete '. J Crushed Aggregate Base Sandy Silt Poorly Graded Sand , _._ Rock I • Silty Sand Poorly Graded Sand with with Sand . Silt I 0 0 I E? m TYPICAL SAMPLER GRAPHIC SYMBOLS OTHER GRAPHIC SYMBOLS 0 o Standard Penetration • Dames & Moore Ring Depth of standing water observed in I Sampler • Sampler borehole a L7 Co x I a I- r LL I o 2 O Z � O 0 O I . ' z � y Soil classifications are based on the Unified Soil Classification System Y Descriptions and stratum lines are interpretive, field descriptions may have been modified to reflect lab test results Descriptions on these logs apply only at the ° w specific boring locations and at the time the borings were advanced, they are not (9 warranted to be representative of subsurface conditions at other locations or rr times 0 t 0 a I Project: Tigard High School _ Log of Boring B-01-2003 Project Location: Durham, Oregon Project Number: 25695560.10001 Sheet 1 of 1 Date(s) I Logged Checked 12/29/2003 DJD TJR I Drilled Drilling By Method Hollow Stem Au Drill Bit By Size/Type 4 7/8 - inch O.D. Total Depth of Borehole 26.5 FT Drill Rig Mobile B -57 Drilling Subsurface Technologies Ap sur ecno es - 190 feet MSL Type Contractor Surface Elevation II Groundwater Level and Date Measured 9 . 0 feet [bgs] Sampling Method(s) Dames & Moore/Splitspoon Hammer Data 140 pound manual hammer Borehole Bentonite Chips Location Backfill SAMPLES rn� C N .0 o -1 p _'S o U r - � m MATERIAL DESCRIPTION I aw a� _ > r �' REMARKS aN N o 0 � CO TA w a o � a E E a w , a L ° �U O0 3 E N _ 190 0 I- z <nC: cC c 0 Li .7'..- • M . - 2" CRUSHED AGGREGATE BASE ROCK - SANDY SILT [ML], fine grained, nonplastic, mottled brown - brownish yellow, stiff, moist. — 185 5 1 . _ I _ 9. 12 32.2 77 9 IP - SP POORLY GRADED SAND [SP], trace silt, sand fine to medium 5Z - grained, brown, medium dense, wet. - 180 10 • 2 14 14 _ 305 1 SM SILTY SAND [SM], with layers of sandy silt, fine grained, —175 15 — nonplastic, light brown and gray, medium dense, wet. 3 21 12 _ 285 • I o - - - 0 N • - - c"? I C 0 - - — 170 2 — — _kg 4 26 18 . SP -SM _ POORLY GRADED SAND WITH SILT [SP -SM], fine grained, 32.8 I light brown, nonplastic, medium dense, very moist. N I rx a - _ 0 . I SP POORLY GRADED SAND [SP], 2" silty sand layer, fine grained, 0 - — — 165 25 brown and gray, medium dense, wet. 0 � 5 19 18 27.4 III U i 5� _ Boring terminated at a depth of 26.5 feet bgs on 12 -29 -2003, _ o o backfilled with bentonite chips and asphalt patched upon o i completion. w - - 0 o o -160 30 0 O. Project: Tigard High School Log of Boring B-02-2003 Project Location: Durham, Oregon Project Number: 25695560.10001 Sheet 1 of 1 Date(s) 12/29/2003 Logged DJD Checked TJR Drilled By By Drilling Method Hollow Stem Au Drill Bit Size/Type 4 7/8 - inch O.D. Total Depth of Borehole 26.5 FT _ Drill Rig Mobile B -57 Drillin Subsurface Technologies Ap - 190 feet MSL Type Contractor Surface Elevation • Groundwater Level and Date Measured 3 feet [bgs] Sampling Dames & Moore /Splitspoon Method(s) Hammer Data 140 pound manual hammer Borehole Bentonite Chips Location Backfill I SAMPLES — o a� C 0 J p 0 U �'�� m" MATERIAL DESCRIPTION 2-z Q REMARKS I _ o a) a . Q v, m Y W w Ow Q E E N Q U ^ (0 L_C/) J N >, 7 NN . as oo cas I— Z u) CC co CC 0 j 0 0 0 15i.>0— 5" ASPHALTIC CONCRETE „ � SM SILTY SAND [SM], fine grained, low plasticity, light brown, loose, moist. I 185 5 Fl I 1 10 1 18 30 86 8 II 180 10 2 9 18 35.5 I SP -SM LAE STH P ], medium 175 15 grained , non , brown AND and gray , medium dense , we t. S 3 23 18 27.3 i M \ O N 9 r sr o N 170 20 \ 4 16 18 2" Layer of gravel @ 20 8' 25.7 I C) \ - • ••• • .•-• _s. M21.0 = SILT WITH SAND [ML], sand fine grained, medium plastic o gray, very stiff, moist a C9 I LL O 165 25 i \ 5 29 18 28.7 I 0 of Boring terminated at a depth of 26.5 feet bgs on 12 -29 -2003, o backfilled with bentonite chips and asphalt patched upon o completion 0 I F- CC 0 • 160 30 0 Project: Tigard High School Project: Log of Boring B -03 -2003 Project Location: Durham, Oregon Project Number: 25695560.10001 Sheet 1 of 1 Date(s) 12/29/2003 • Logged DJD Checked TJR ' Drilled By By Drilling Hollow Stem Auger Drill Bit 4 7/8 -inch O.D. Total De 26.5 FT Method Size/Type of Borehole Drill Rig Mobile B -57 Drilling Subsurface Technologies Ap — 190 feet MSL I Type Contractor Surface Elevation Groundwater Level and Date Measured 7 . 0 feet [bgs] Sampling Method(s) Dames & Moore /S Hammer Data 140 pound manual hammer Borehole Bentonite Chips Location Backfill i SAMPLES C a.. o -J p o 3 43 �'�� r o� MATERIAL DESCRIPTION 0. REMARKS Q.... 43 . i l.lw 0. a) x' V N L o ' Cl) x I Z CO CC W' o J 20 0 C 190 0 SM SILTY SAND [SM], fine grained, nonplastic, light brown, medium I _ _ dense, moist. _ • I • — 185 5 — _ 1 16.1 18 31.9 SP - POORLY GRADED SAND [SP], fine grained, light brown, medium dense, moist. Pi 1 SP POORLY GRADED SAND [SP], trace gravel, trace silt, fine _ grained, brown, medium dense, moist to wet. - — 180 10 — 2 29 18 27.3 1 i . SM SILTY SAND [SM], 2" layer of poorly graded sand, fine grained, 175 15 — brown and light brown, medium dense, wet. — 3 29 18 ' • _ 31.3 I •• °o - _ N M 9 - - • 0 - - 0 — 170 20 — — 4 26 18 30 1 a SP POORLY GRADED SAND [SP], fine grained, brown, medium dense, wet. I 0 a - - 0 I LL - - 0 — 165 25 5 21 18 y ML ._ SANDY SILT [ML], fine grained, low plasticity, gray, very stiff, wet. _ 36 8 I o ii Boring terminated at a depth of 26,5 feet bgs on 12 -29 -2003 and o backfilled with bentonite chips upon completion. 0 W - - 0 a. 1 0 - 0 —160 30 a IX URS Subsurface Technologies I Operator W MCC / A.MEE CPT Date/Time • 12 -29 -03 1204 Sounding. SND583 Location CPT1 TIGARD HS Cone Used: 442 TC Job Number: 25144AA00100 ' Tip Resistance Local Friction Friction Ratio Pore Pressure Diff PP Ratio Soil Behavior Type - Qt (Ton /ft^2) Fs (Ton /ft^2) Fs /Qt ( %) Pw (psi) (Pw- Ph) /Qt ( %) Zone. UBC -1983 0 0 300.0 0.0 5.0 0 0 5.0 -20 0 100.0 -20.0 100.0 0.0 12.0 0.00 I I I I I I 1 I I I I 1 I I I I I �TT 111 i ii n i 1 I I 500 — — — — — — — — - 111 10.00 — — — — _ _ _ _. _ _ • i ' 15.00 — . - — — — '. — — ` — — — — i IIII 20.00 i .. — — — — — — ' i - . . • Depth I (ft) 2 : _ 5.00 — , I - i i i l .. .. . I_ I I! I i i _,› I 30.00 — - f -; _ _ I - r I ' f j — _ __, 35.00 l— — ' -- - / — ...._.. t _ _ _ r I 40.00 . _ — _ 1 111..; 1 i 1 1 . : : : fi r 4T , 4 5.00 i Maximum Depth = 44.95 feet Depth Increment = 0.33 feet I 1 sensitive fine grained 4 silty clay to clay 7 silty sand to sandy silt 10 gravelly sand to sand 2 organic material 5 clayey silt to silty clay 8 sand to silty sand 11 very stiff fine grained (') 3 clay ig 6 sandy silt to clayey silt 9 sand g 12 sand to clayey sand (') Subsurface Technologies Operator: W.MCC / A.MEE CPT Date/Time. 12 -29 -03 12:04 I Sounding: SND583 Location. CPT1 TIGARD HS Cone Used 442 TC Job Number 25144AA00100 Tip Resistance Soil Behavior Type* SPT N* Seismic Delay Seismic Velocity Qt (Ton;ft ^2) Zone UBC -1983 60% Hammer (milliseconds) (Meters/Second) 0.0 300.0 0.0 12.0 0.0 250.0 0.0 60.0 00 400 0 1,1 F+ 5.00 — — - — -- • _ — — — — I 10.00 — — ' } � — #.'f=. I _ t� — 15.00 — — -- , _ — — : ' : - — • 20.00 — — _ — _ — _ 1, Depth (ft) tt tit _ — — 25.00 — _ __ E.. — • i , , t ry.. I • I 30.00 — I ► . 14. — — 35.00— _ — I i I 40.00 — — — — . { 'i,q.'ti`; I I 1 — -- 45.00 Maximum Depth = 44.95 feet Depth Increment = 0,33 feet I 1 sensitive fine grained 4 silty clay to clay C 7 silty sand to sandy silt 10 gravelly sand to sand 2 organic material 5 clayey silt to silty clay 8 sand to silty sand 11 very stiff fine grained (*) 3 clay II 6 sandy silt to clayey silt 9 sand a 12 sand to clayey sand (`) I Subsurface Technologies Operator: W MCC / A MEE CPT Date/Time: 12 -29 -03 16:17 I Sounding SND585 Cone Used: 442 TC Location: CPT2 TIGARD HS Job Number: 25144AA00100 r Tip Resistance Local Friction Friction Ratio Pore Pressure Diff PP Ratio Soil Behavior Type* Qt (Ton /ftA2) Fs (Ton /ft ^2) Fs /Qt ( %) Pw (psi) (Pw- Ph) /Qt ( %) Zone: UBC -1983 0.0 300,0 0.0 5.0 0.0 5.0 -20.0 100.0 -20.0 100 0 0.0 12.0 r 0.00 1 I 1 1 I 1 1 1 1 l i i i I i I — IT I l I I l I1IttlIIIIII i I I - -- - -. — - _ # - 1000 I I 20.00 — — — — — — — — _ •— — I, .. I - E 01 40.00 _ — — — — — I- — i Depth r O • 50.00 — _ _ _ _ _ — — — — !Iloilo _ j I I € / I 60.00 — — — — — — — — I • 70.00 — ;* II • I • • 1 I i 80.00 — _ I _ • I 90.00 Maximum Depth = 84 97 feet Depth Increment = 0.33 feet I 1 sensitive fine grained 4 silty clay to clay 7 silty sand to sandy silt 10 gravelly sand to sand 2 organic material 5 clayey silt to silty clay 8 sand to silty sand 11 very stiff fine grained ( *) 3 clay • 6 sandy silt to clayey silt 9 sand * 12 sand to clayey sand ( *) I Subsurface Technologies Operator: W.MCC / A.MEE CPT Date/Time 12 -29 -03 16:17 I Sounding. SND585 Cone Used: 442 TC Location: CPT2 TIGARD HS Job Number' 25144AA00100 I Tip Resistance Soil Behavior Type* SPT N* Seismic Delay Seismic Velocity Qt (Ton /ft^2) Zone: UBC -1983 60% Hammer (milliseconds) (Meters/Second) 0.0 300.0 0.0 12.0 0.0 250.0 0.0 100.0 0 0 400 0 I 0.00 I I 1 I - -- — I — k i t t t i I I I I i 1 I I I I I I I 1 I I I I I T I I I I IT I 10.00 — — emu. I I 20.00 — — 7.4444 r - - _ _ _ - i „, 30.00 ' , - - - - 40.00 - ! ._... r -._._ _. _ - _ _: — i - De th I —_ p i 1 I (ft) - - - - - -tea. 50 — __. ..__ Ior _ rs .. - 1 I 1 60.00 — �— — _ _ _ _ i i i I ' - _. 7 0.00 — _ _ _ - - - - 1 i I i i • • I 8000 — i 1 I i I 90.00 _ 1 ■ _ Maximum Depth = 84.97 feet Depth Increment = 0.33 feet I 1 sensitive fine grained 4 silty clay to clay 7 silty sand to sandy silt 10 gravelly sand to sand 2 organic material 5 clayey silt to silty clay 8 sand to silty sand 11 very stiff fine grained (`) 3 clay ■ 6 sandy silt to clayey silt 9 sand a 12 sand to clayey sand O I