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Geotechnical Subsurface Exploration - Police Building Additions - 1997 .. No wr GEOTECHNICAL SUBSURFACE EXPLORATION CITY OF TIGARD POLICE BUILDING ADDITIONS TIGARD, OREGON VIM Submitted To: Iwo Utilities Engineer City of Tigard 13125 SW Hall Boulevard Tigard, Oregon 97223 7-61 M-09620-0 December 1997 Copyright ° 1997 by AGRA Earth & Environmental, Inc. All rights reserved. AGRA Earth & Environmental 9r ENGINEERING GLOBAL SOLUTIONS r. AD- AGRA Earth & Environmental AGRA Earth B ENGINEERING GLOBAL SOLUTIONS Environmental, Inc. No 7477 SW Tech Center Drive Portland,Oregon December 4, 1997 USA 97223-8025 Tel (503)639-3400 wr 7-61 M-09620-0 Fax (503)620-7892 Mr. Greg N. Berry Utilities Engineer rr City of Tigard 13125 SW Hall Boulevard Tigard, Oregon 97223 Dear Mr. Berry: RE: GEOTECHNICAL SUBSURFACE EXPLORATION CITY OF TIGARD - POLICE BUILDING ADDITIONS TIGARD, OREGON iYirr AGRA Earth & Environmental, Inc. (AEE) is pleased to provide this subsurface exploration and geotechnical engineering report for the subject project. It is our opinion that the site is geotechnically suitable for the proposed development, subject to the recommendations provided in this report. We have conducted a site-specific seismic hazard study in accordance with OSSC Section 1804. Based on the results of this study, the seismic design of the building can be done using WIN the UBC design criteria for Zone 3 and soil type S2. If you have any questions regarding this report, please feel free to contact the undersigned at (503) 639-3400. Sincerely, AGRA Earth & Environmental, Inc. Rajiv Ali, Ph.D. A. Wesley Speg, Ph. ,P.�— Geotechnical Engineering Staff Principal Geotechnical Engineer r■ ... RA/klp rr irr 9620.L&R No City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page i wr TABLE OF CONTENTS PAGE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 .0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.0 SITE AND PROJECT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3.0 SITE EXPLORATION AND SUBSURFACE CONDITIONS . . . . . . . . . . . . . . . . . . . 1 3.1 SITE EXPLORATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3.2 SUBSURFACE CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4.0 SEISMIC HAZARD STUDY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 r 5.0 RECOMMENDATIONS AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.1 SITE PREPARATION . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 7 5.1 .1 Dry Weather Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1 .2 Wet Weather Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.2 PROOF-ROLLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5.3 FILLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5.4 CUT AND FILL SLOPES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.5 RETAINING WALLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.5.1 Restrained Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 .. 5.5.2 Non-Restrained Walls . . . . . . . . . . . . . . . . . . . . . 11 5.5.3 Retaining Wall Backfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.5.4 Wall Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 IIiIIIIIIIP 5.6 FOUNDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.7 SUBSURFACE DRAINAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 5.8 FLOOR SLABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 so 5.9 EROSION CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5.10 UNDERGROUND UTILITIES & EXCAVATION . . . . . . . . . . . . . . . . . . . . . 13 a. 6.0 FUTURE GEOTECHNICAL SERVICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.0 LIMITATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 +�+• List of Appendices Appendix A Field Investigation aw Appendix B Site Specific Seismic Response Spectra AGRA Earth & Environmental YIY ENGINEERING GLOBAL SOLUTIONS .r City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page ii SUMMARY wr This report presents the findings, conclusions, and recommendations of our Geotechnical Subsurface Exploration performed for the proposed City of Tigard - Police Building Addition in Tigard, Oregon. The exploration was conducted to identify the surface and subsurface conditions at the site and to provide geotechnical design criteria and construction recommendations for use by the project designers and builders. The site is geotechnically suitable for the development of the proposed facility subject to the recommendations presented in this report. Key findings are briefly highlighted below. wr • The soil conditions encountered at the site typically consist of asphalt pavement and landscaping areas underlain by Willamette Silts. Asphalt pavement, landscaping fills and other unsuitable materials should be removed from building, pavements and structural fill areas (Section 5.0). • It is recommended that the site be prepared during dry weather due to the moisture sensitive nature of the near-surface soils. However, we have provided recommendations for both dry weather and wet weather construction. • Foundations can be designed for an allowable bearing pressure of 2500 psf. This r pertains to a foundation width of at least 12 inches and bearing on undisturbed native soil or structural fill at least 18 inches below the lowest adjacent grade. +� Most of the on-site soils should be able to be excavated with a standard backhoe for utility installation (Section 5.10). A site-specific seismic study was performed in accordance with OSSC Section 1804. Seismic design for the structure can be based on the UBC design spectra for Zone 3, soil type S2 (Section 4.0). The preceding summary is intended for introductory and reference uses only. This report should be read in its entirety in order to understand the details of the recommendations and to be familiar with their bases and limitations. ': AGRA Earth & Environmental yam/ ENGINEERING GLOBAL SOLUTIONS City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 1 r 1.0 INTRODUCTION .r. This report presents the results of,a subsurface exploration and geotechnical engineering report prepared by AGRA Earth & Environmental, Inc. (AEE) for the proposed City of Tigard - Police ,. Building Addition in Tigard, Oregon. The location of the site is shown on the Site Location Map, Figure 1 . The proposed development and exploration locations are shown on the Site Plan, Figure 2. The purpose of this study was to establish general surface and subsurface conditions in the proposed development area on which to base our geotechnical design criteria and construction w recommendations for grading, retaining walls, foundations, drainage etc. A site-specific seismic hazard study was also conducted in accordance with Section 1804 of the Oregon Structural Specialty Code (OSSC). +r. This work has been completed in accordance with our proposal P97-576 dated October 29, 1997. The scope of work for this project included a review of geologic and geotechnical reports for the project vicinity, surficial geotechnical reconnaissance, subsurface exploration, and geotechnical engineering analyses. This report has been prepared for the exclusive use of the City of Tigard and their agents for specific application to this project in accordance with generally accepted geotechnical engineering practice. This report may not contain sufficient information for purposes of other parties or other uses. ww 2.0 SITE AND PROJECT DESCRIPTION The proposed building site is located north of the existing Police Headquarters in Tigard, Oregon. The site is relatively flat and is covered with asphalt parking and landscaping areas. The proposed project will consist of the construction of an approximately 3000 square-foot single-story addition to the Police Headquarters. The construction is planned to be typical wood / steel frame with brick masonry. The maximum column and perimeter foundation loads r are anticipated to be of the order of 100 kips and 6 kips per lineal foot, respectively. It is our understanding that no basements are planned. .r 3.0 SITE EXPLORATION AND SUBSURFACE CONDITIONS The near surface soils consist of silts of the Aloha Series (Soil Survey of Washington County, Oregon). These soils are relatively poorly drained and are formed in alluvial or lacustrine areas on broad valley terraces. Ground slopes vary from 0 to 3 percent. The surface soils are underlain by weathered Troutdale Formation followed by Columbia- River basalt (CRB). The �. upper 100 to 200 feet of CRIB is deeply decomposed and weathered. 3.1 SITE EXPLORATION Our surface and subsurface investigation for this project was performed on November 14, 1997. The exploration program consisted of surface geotechnical reconnaissance, and three L AGRA Earth & Environmental il�r ENGINEERING GLOBAL SOLUTIONS go City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 2 we cone penetration test soundings (CPT). The CPT locations are shown on the attached Site 60 Plan, Figure 2. The CPT locations were located by pacing from identifiable topographic features shown on the furnished plans, and should be considered approximate. CPT sounding data are included in Appendix A at the end of this report. Shear wave velocity tests were do performed in one of the CPT soundings to assist in the seismic hazard study. 3.2 SUBSURFACE CONDITIONS aw The subsurface conditions were interpreted based on the results of the CPT soundings and a review of geologic literature for the project site. The general soil profile consists of asphalt No pavement and landscaping areas underlain by Willamette Silt. Subsurface conditions are discussed below: Asphalt Pavement and Landscaping Areas: Asphalt pavement over six to eight inches of base rock was encountered over most of the proposed building areas. Some areas are also covered with landscaping fills. Willamette Silt: Below the pavement and landscaping fills is a moist to wet layer of stiff, clayey silt to silty clay. Some lenses of clay and sandy silt were also interpreted within this layer based on results of CPT soundings. This layer extends to a depth of approximately 45 to 50 feet below the existing ground surface. wr Weathered Troutdale Formation: The weathered Troutdale Formation was generally interpreted at a depth of 45 to 50 feet below the existing ground surface based on the CPT sounding data. This material was encountered to the maximum depth explored. Groundwater: Groundwater was interpreted at depths of 10 to 12 feet below the existing °w ground surface based on the results of CPT soundings. It is possible that perched groundwater may occur during wet periods in variable and unpredictable locations. wr 4.0 SEISMIC HAZARD STUDY A site-specific seismic hazard study was performed for the property in accordance with Section 1804 of the Oregon Structural Specialty Code (OSSC). This amendment requires that sites which will contain certain structures (as defined by ORS 455.447) be investigated for dw susceptibility to seismic-induced geologic hazards. This section presents the results of our study and includes an evaluation of site ground shaking characteristics as well as other seismic-related hazards. we Seismicity and Earthquake Sources VW The seismicity of the Portland metropolitan area, and hence the potential for ground shaking, is controlled by three separate fault mechanisms. These include the Cascadia Subduction Zone ' 4ft AGRA Earth & Environmental YIYENGINEERING GLOBAL SOLUTIONS City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 3 (CSZ), the mid-depth intraplate zone, and relatively shallow crustal zone sources. Descriptions of these potential earthquake sources are presented below. The Cascadia Subduction Zone is located offshore and extends from Northern California to err British Columbia. Within this zone the oceanic Juan De Fuca Plate is being subducted beneath the continental North American Plate to the east. The interface between these two plates is located at a depth of approximately 15 to 20 kilometers. The seismicity of the CSZ is subject .r to several uncertainties, including the maximum earthquake magnitude and the recurrence intervals associated with various magnitude earthquakes. Anecdotal evidence of previous CSZ earthquakes has been observed within coastal marshes along the Oregon coast (Peterson et. al., 1993). Sequences of interlayered peats and sands have been interpreted to be the result of large subduction zone earthquakes occurring at intervals on the order of 300 to 500 years with the most recent event taking place approximately 300 years ago. A recent study by Geomatrix (1995) suggests that the maximum earthquake associated with the CSZ is a moment magnitude (MW) 8 to 9. This is based on an empirical expression relating moment WW magnitude to the area of fault rupture derived from earthquakes which have occurred within subduction zones in other parts of the world. A moment magnitude 9 earthquake would involve a rupture of the entire CSZ. As discussed by Geomatrix (1995) this has not occurred No in other subduction zones which have exhibited much higher levels of historical seismicity than the CSZ and is considered unlikely. For the purpose of this study an earthquake of moment magnitude 8.5 was assumed to occur within the Cascadia Subduction Zone. �r The intraplate zone encompasses the portion of the subducting Juan De Fuca Plate located at a depth of approximately 20 to 40 km below Western Oregon. Very low levels of seismicity have been observed within the intraplate zone in Oregon. However, much higher levels of seismicity within this zone have been recorded in Washington and California. Several reasons for this seismic quiescence were suggested in the Geomatrix (1995) study and include ` changes in the direction of subduction between Oregon and British Columbia as well as the effects of volcanic activity along the Cascade Range. Historical activity associated with the intraplate zone include the 1949 Olympia magnitude 7.1 and the 1965 Puget Sound magnitude 6.5 earthquakes. Based on the data presented within the Geomatrix (1995) report an earthquake of magnitude 7.25 has been chosen to represent the seismic potential of the intraplate zone. The third source of seismicity that can result in ground shaking within the greater Portland area w. is near-surface crustal earthquakes occurring within the North American Plate. The historical seismicity of crustal earthquakes in western Oregon is higher than the seismicity associated with the CSZ and the intraplate zone. The 1993 Scotts Mills (magnitude 5.6) and Klamath �. Falls (magnitude 6.0) earthquakes were crustal earthquakes. Seismic and geologic parameters such as slip rate, horizontal and vertical offset, rupture length, and geologic age have not been determined for the majority of the above faults. This is primarily due to the lack of surface expressions or exposures of faulting because of urban development and the presence of late Quaternary soil deposits which overlie the faults. The AGRA Earth & Environmental SIU/ ENGINEERING GLOBAL SOLUTIONS +�+ City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 4 wr low level of historical seismicity (particularly for earthquakes greater than magnitude 5) and lack of paleo-seismic data results in large uncertainties when evaluating individual crustal fault maximum magnitude earthquakes and recurrence intervals. Thus it is considered prudent to also evaluate the potential for seismic shaking due to crustal earthquakes on a regional scale. Based on data presented by Geomatrix (1995) and DOGAMI (1199 1) the seismic exposure at the site from crustal zone sources is represented by an earthquake of magnitude 6.5. Individual faults or fault zones which have been mapped by the Oregon Department of Geology +r� and Mineral Industries (199 1) and Geomatrix (1995) within the near-vicinity of the site include the following: Approximate Closest Fault System Distance To Site (miles) Portland Hills Fault Zone 10 Bolton Fault 13 Grant Butte, Damascus-Tickle Creek Fault Zone 17 Helvetia Fault 14 Lacamas Creek Fault 18 Sandy River Fault 25 Mount Angel Fault 25 ,,. Newberg Fault 16 Sherwood Fault 11 Beaverton Fault Zone 9 ++� Frontal Fault Zone 23 Waldo Hills Fault Zone 38 Mill Creek Fault Zone 50 Salmon River Fault Zone 44 Gales Creek Fault 22 Clackamas River Fault Zone 44 Bedrock Acceleration The acceleration within the underlying bedrock (at this site considered to be the Columbia River Basalt) expected due to an earthquake occurring within the above-described seismic sources was calculated based on the maximum earthquake magnitude and empirical distance- attenuation relationships developed by Geomatrix (1995) and Joyner and Boore (1982). The following table presents the estimated peak bedrock accelerations at the site for the different r earthquake sources: w. AGRA Earth & Environmental >IIIr' ENGINEERING GLOBAL SOLUTIONS City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 5 Yrr Table I Potential Earthquake Source Parameters Earthquake Maximum Epicentral Peak Horizontal Source Moment Depth (km) Distance (km) Acceleration (g) Magnitude Crustal Zone 6.5 10 10 0.26 Intraplate Zone 7.25 30 35 0.20 CSZ 8.5 15 120 0.10 .Iw The peak horizontal bedrock acceleration for the crustal zone earthquake (0.26g) was increased to 0.30g for conformance with the minimum level of bedrock acceleration specified in accordance with OSSC amended Section 1804. Ground Acceleration and Response Spectra +rr+ The potential for ground shaking (as represented by the peak horizontal ground acceleration +r. and response spectra) was evaluated by applying an acceleration time history record to the base of the site soil profile and determining the response at the ground surface. No recorded acceleration records are available from an earthquake within the Cascadia Subduction Zone. An acceleration record obtained from the 1985 Mexico City earthquake (a subduction zone event) was used to represent potential CSZ bedrock motions. Additionally, a synthetic time history record developed by Seed and Idriss (1969) to model a magnitude 8+ earthquake was orw used to assist in evaluating the response of the site to a magnitude 8.5 earthquake. Recorded time histories are available from the 1949 Olympia and 1965 Puget Sound earthquakes and were used to analyze the response of the site to an interplate zone earthquake. Ground shaking characteristics due to crustal zone sources were evaluated using two near-surface California earthquake records. Parameters of the selected earthquake time histories are presented below: Table II Selected Earthquake Acceleration Time Histories +rw Earthquake Record Epicenter Peak Horizontal Magnitude Distance (km) Acceleration (g) aw Mexico City (1985) 8.1 131 0.17 Synthetic 8+ N.A. 0.32 r Olympia (1949) 7.1 26 0.28 Puget Sound (1965) 6.5 62 0.20 Castaic (197 1) 6.5 30 0.32 Lake Hughes (197 1) 6.5 1 32 0.15 AGRA Earth & Environmental "W ENGINEERING GLOBAL SOLUTIONS i ++�+ City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 6 +r The peak horizontal accelerations of the above time histories were scaled to match the peak horizontal accelerations shown in Table I. Horizontal ground accelerations and response spectra were calculated for the site by propagating the individual earthquake acceleration time history records up through the soil profile using the computer program SHAKE91 (ldriss, 1991). The soil profile was developed from the exploratory CPT soundings, and geologic information presented by DOGAMI (1991) + for the general vicinity of the site. Table III Representative Soil and Shear Wave Profile +• Depth (ft) Geologic Unit Shear Wave Velocity (ft/sec) or 0-50 Willamette Silts 500 – 1000 50-500 Weathered Troutdale 1000 - 2000 >500 —t—Columbia River Basalt >2000 Results of the analyses indicate that peak ground horizontal accelerations are approximately 0.30g, 0.25g, and 0.14g for the crustal zone, intraplate zone and CSZ earthquakes, respectively. Calculated response spectra for 5% structural damping are presented in Figures B1 through B3. Also shown is the Uniform Building Code (UBC) Zone 3 response spectrum for a S-2 soil profile. It is observed that the majority of the spectral values for the earthquakes selected to represent potential ground motions at the site are bounded by the UBC response spectrum. The natural period of the building addition is estimated to be in the range of 0.1 to 0.2 seconds. It is recommended that the UBC Zone 3 spectrum for a S2 soil type be used for the seismic design of the structure. The above results are deterministic based and do not include probabilistic assessments of the frequency (i.e. recurrence intervals) at which such ground motions may occur. This is primarily due to the lack of historical seismicity of earthquake events greater than magnitude 5 in western Oregon. In their recent study, Geomatrix (1995) estimated peak bedrock horizontal ..w accelerations in Portland of 0.19g, 0.26g, and 0.36g for return periods of 500, 1000 and 2500 years, respectively. The majority of these bedrock accelerations were attributed to crustal earthquake sources. The bedrock accelerations for return periods of 500 and 1000 years are less than those used in the above analyses for crustal earthquake sources. Fault Displacement and Subsidence There are no mapped faults within the boundaries of the site or within adjacent properties. No w evidence was encountered during the field investigation to suggest the presence of faults 'j AGRA Earth & Environmental VIII/ ENGINEERING GLOBAL SOLUTIONS �r City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 7 rw within the property. It is our opinion that the potential for fault displacement and associated ground subsidence is remote. Landslide There are no landslide or slope stability hazards at the site due to the relatively flat topography of the site and surrounding areas. +rr Liquefaction The potential for liquefaction within the site was evaluated using the CPT sounding data, and available geotechnical information for surrounding sites. The seismic loading was assumed to consist of a Magnitude 6.5 earthquake with a peak horizontal ground acceleration of 0.30g. Liquefaction resistance was analyzed based on the work of Stark & Olson (1995) and Seed & deAlba (1986). These analyses consist of evaluating the induced shear stress in the ground from seismic shaking with respect to the shear stress required for liquefaction to occur. The medium stiff to stiff Willamette silts are not susceptible to liquefaction with the exception of the layer between 17 and 23 feet. An analysis of the vertical settlement resulting from 4110 liquefaction using the methods of Tokimatsu & Seed (1987) and Ishihara & Yoshimine (1992) indicates a post liquefaction settlement of this layer of approximately 1 to 1 .5 inches. Ground surface disruption would be less due to the presence of overlying liquefaction-resistant soils. 40 The potential for lateral spreading is considered minor due to the relatively flat topography of ar the site and surrounding areas. Tsunami and Seiche Inundation rr There is no potential for tsunami- and seiche-related damage at the site due to the site's elevation and distance from coastal areas, waterways and lakes. 5.0 RECOMMENDATIONS AND CONCLUSIONS r 5.1 SITE PREPARATION Prior to beginning construction, areas of the site that will receive structural fill, foundations, floor slabs, or pavement should be cleared of topsoil, old fills, and any other existing site improvements (such as drain tiles, foundations, septic tanks, etc.) down to firm native silts. N• The asphalt pavement and landscaping fills should be removed from the building slab areas. Failure to remove previous improvements may cause moisture to enter structural fills, or migrate under floor slabs or pavements, possibly leading to excessive settlement or premature am slab or pavement failure. LAS AGRA Earth & Environmental IrIY ENGINEERING GLOBAL SOLUTIONS so City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 8 wr After removal of existing site improvements, and stripping of demolition debris, fill, topsoil and any other soft, or unsuitable material, we recommend that the resulting exposed subgrade be observed by a representative from our office. We have provided recommendations for both wet weather and dry weather construction. However, due to the moisture sensitive soils at this site, we recommend that the site be prepared during relatively dry weather. If wet weather grading is attempted, development �r costs could be significantly higher due in part to the increased cost of imported granular fill. 5.1.1 Dry Weather Construction IRS We recommend that the subgrade for pavement and structural fill areas be scarified to a depth of at least eight inches. The scarified soil should be aerated as necessary to achieve the proper moisture content, and compacted to at least 92% of the maximum dry density determined in accordance with ASTM D-1557. Minimum compaction for the eight-inch-thick layer immediately underlying pavement sections should be 95%. Even during dry weather it is possible that some areas of the subgrade will become soft or may "pump", particularly in deeper cuts and in poorly drained areas. Soft or wet areas that cannot be effectively dried and compacted should be prepared in accordance with Section 5.1 .2. 5.1.2 Wet Weather Construction During wet weather, or when adequate moisture control is not possible, it may be necessary to install a granular working blanket to support construction equipment and provide a firm base on which to place subsequent fills and pavements. Commonly the working blanket consists of a bank run gravel or pit run quarry rock (six to eight inch maximum size with no more than 5% by weight passing a No. 200 sieve). We recommend that we be consulted to approve the material before installation. The working blanket should be installed on a stripped subgrade in a single lift with trucks end- dumping off an advancing pad of granular fill. During prolonged wet weather final stripping and/or cutting may have to be accomplished with a large smooth bucket trackhoe or similar equipment, working from the advancing pad of granular fill. After installation, the working blanket should be compacted by a minimum of four complete passes with a moderately heavy static steel drum or grid roller. We recommend that we be retained to observe the granular working blanket installation and compaction. The working blanket must provide a firm base for subsequent fill installation and compaction. VIA It has been our experience that about 12 inches of working pad is normally required, depending on the gradation and angularity of the working pad material. This assumes that the material is placed on a relatively undisturbed subgrade in accordance with the preceding as recommendations, and that it is not subjected to frequent heavy construction traffic. ,r AGRA Earth & Environmental Wim' ENGINEERING GLOBAL SOLUTIONS City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 9 ++r Areas used as haul routes for heavy construction equipment may require a working pad thickness of two feet or more. If particularly soft areas are encountered, a heavy grade, non- woven, non-degradable filter fabric installed on the silt subgrade may help to prevent silt from entering the working blanket. If desired, we can provide you with sample specifications for Iti this material. Construction practices can greatly affect the amount of working pad necessary. By using +r tracked equipment and special haul roads, the working pad area can be minimized. The routing of dump trucks and rubber tired equipment across the site can require extensive areas and thicknesses of working pad. Normally the design, installation and maintenance of a working pad is the responsibility of the contractor. 5.2 PROOF-ROLLING Regardless of which method of subgrade preparation is used (i.e. wet weather or dry weather), we recommend that prior to fill placement or base course installation, the subgrade or granular working blanket be proof-rolled with a fully-loaded 10 to 12 yard dump truck. This pertains to pavement and structural fill areas. Areas of the subgrade that pump, weave or appear soft and muddy should be scarified, dried and recompacted, or overexcavated and backfilled with compacted granular fill. If a significant length of time passes between fill placement and commencement of construction operations, or if significant traffic has been routed over these areas, we recommend that the subgrade be similarly proof-rolled again before any foundation or pavement installation is allowed. We recommend that we be retained to observe this operation to check conformance with these guidelines. 5.3 FILLS Structural fills should be installed on a subgrade that has been prepared in accordance with the recommendations in Sections 5.1 and 5.2 of this report. Fills should be installed in horizontal lifts not exceeding about eight inches in thickness, and should be compacted to at least 92% of the maximum dry density for silts (this would pertain to native soils) and 95% for imported sands and gravels. The top eight inches of pavement subgrade should be compacted to 95%. Relative compaction should be referenced to ASTM D-1557. This criteria may be reduced to 85% in level, non-structural areas consisting landscaping or planter areas. Finished slopes and fills in areas of existing slopes should be in accordance with Sections 5.4. During dry weather, structural fills may consist of relatively well-graded soil that is free of debris and organic matter that can be compacted to the preceding specifications. However, if excess moisture causes the fill to pump or weave, those areas should be dried, or removed and backfilled with compacted granular fill. j AGRA Earth & Environmental aENGINEERING GLOBAL SOLUTIONS City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 10 r 5.4 CUT AND FILL SLOPES Cut slopes less than 10 feet in height should be sloped no steeper than 2H:1 V. Cut slopes higher than 10 feet should be individually designed. These values assume that the slopes will .�. be protected from erosion and that significant drainage will not occur over the face of the slope. Fill compaction should be in accordance with Section 5.3. The maximum fill slopes should be 2H:1 V for fills up to 10 feet in height. For fills higher than 10 feet, AEE should be contacted to evaluate slope stability and settlements. 5.5 RETAINING WALLS The tables presented in this section summarize our recommendations for design of retaining structures. These values represent our best estimates of long term pressures that will develop in an active or at-rest state of stress. These values include no allowance for hydrostatic pressures and assume that retaining structures will be provided with a drainage system in �. accordance with subsequent sections of this report. If backfill is in direct contact with the wall, these forces can be assumed to act at a downward inclination of 20 degrees from horizontal. If friction is prevented by drainage membranes or water proofing membranes, then the forces should be assumed to act horizontally. +r The following retaining wall design parameter do not include a factor of safety and nor do they include any surcharge loading from traffic or other element. 5.5.1 Restrained Walls Restrained walls are any walls that are prevented from rotation during backfilling and after construction. Most basement walls are restrained by a floor diaphragm or roof and fall into the category of restrained walls. In addition, any retaining walls that are rigidly connected to buildings or that make sharp bends may fall into this category. We recommend that restrained walls be designed for soil pressures derived from the criteria shown in the following table. Backfill Slope Equivalent Fluid Unit Weight Horizontal/Vertical lbs./cu. ft. r. Level 40 3H:IV 60 2H:IV 90 AGRA Earth & Environmental 11111 ENGINEERING GLOBAL SOLUTIONS City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 11 5.5.2 Non-Restrained Walls Non-restrained walls have no restraint at the top and are free to rotate about their base. Most cantilever retaining walls fall into this category. We recommend that non-restrained walls be designed for soil pressures derived from the criteria shown in the following table. Backfill Slope Equivalent Fluid Unit Weight Horizontal/Vertical lbs./cu. ft. Level 30 3H:IV 50 2H:IV 80 5.5.3 Retaining Wall Backfill Backfill behind retaining walls should consist of free-draining granular material. To minimize pressures on basement walls, we recommend the use of crushed rock backfill (conforming to ODOT Standard Specification Section 00510.12 with the addition that no more than 5% by weight pass the Number 200 Sieve). Use of other material could increase wall pressures. Overcompaction of this fill can greatly increase lateral soil pressures. We recommend that wall backfill be compacted to between 90% and 92% maximum dry density as determined by Modified Proctor (ASTM D-1557) testing. ilrr 5.5.4 Wall Drainage We recommend that basement and retaining walls be provided with a drainage system to alleviate seepage through the walls and additional hydrostatic lateral pressures. All drains should be protected by a filter fabric to prevent internal soil erosion and potential clogging. 5.6 FOUNDATIONS +r� Foundation support for the proposed structure may be obtained from either the native, non- organic, silty clay to clayey silt or from new engineered fill. a recommend that foundations do be designed for an allowable bearing pressure of 2,500 psf. /his pertains to footings that are a minimum of 12 inches wide, bear on undi tive soil or structural fill, and are a minimum of 18 inches below lowest adjacent, stripped, exterior grade. This bearing pressure may be increased by one-third for short-term wind or seismic loading. The total estimated settlement will be on the order of one inch for loads up to 100 kips and 6 kips/ft for columns and continuous footings, respectively. We expect that most of this settlement will be completed within a few months after construction. W. AGRA Earth & Environmental ilk ENGINEERING GLOBAL SOLUTIONS r City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 12 For passive pressures in resistance to lateral loads a 350 pcf equivalent fluid pressure may be used for the silty clays to clayey silts, excluding soil within one foot of the surface where no passive resistance should be used in design. A base friction equal to 40% of the vertical load may also be used at the base of foundations as sliding resistance. Irr If foundations are excavated during wet weather, it may be necessary to install a layer of crushed rock or lean concrete in footing bottoms to minimize subgrade disturbance during placement of forms and reinforcement steel. 5.7 SUBSURFACE DRAINAGE Irr Perimeter foundation drains are recommended around the building perimeter adjacent to the footing base. The purpose of perimeter drains is to protect against lateral migration of rr groundwater. AEE recommends perimeter drains to ensure that the soil surrounding the foundation can drain rapidly whenever necessary. Perimeter foundation drains are usually constructed at, or slightly below, the base elevation of the footings using 4 inch diameter perforated PVC pipe bedded in drain rock and sloped to drain by gravity. A filter fabric is generally placed between fine-grained soils and the drain rock to minimize infiltration of fines into the rock. A typical detail of a perimeter drain is presented in Figure 3a. If the finished floor level is below the adjacent grades, an underslab drainage system is r.r recommended. An underslab drainage system will assist in reducing the potential for high water to result in hydrostatic pressures against the bottom of the floor slabs. Typical underslab drains are constructed with 4 inch perforated PVC pipe embedded in a 12 inch layer of open graded crushed rock. The PVC pipes can also be installed in the pit run rock mat. A typical detail of an underslab drain is presented in Figure 3b. In addition, positive surface drainage should be maintained away from the building foundations during construction. The finish grading should also provide for permanent, positive surface drainage away from the building. Surface water sources such as roof drains and parking lot runoff should be routed independently through non-perforated drain lines to a storm water collection system. Surface water should not be allowed to enter subsurface drainage systems. 5.8 FLOOR SLABS Subgrade for floor slab-on-grade should be prepared in accordance with Section 5.1 . A minimum of 6 inches of compacted crushed rock should be installed over the prepared subgrade to provide a base for the concrete slab. This crushed rock material should be well- graded, angular, and contain no more than 5% passing a U.S. standard No. 200 sieve. While the seasonal high groundwater table is not expected to approach the floor slab elevation, the soils are prone to lateral seepage of infiltrated surface water. The migration of water vapor may result in the loosening of flooring materials attached with mastic, the warping of wood flooring, and, in extreme cases, mildewing of carpets and building contents. For most finished 40 Aft AGRA Earth & Environmental �' ENGINEERING GLOBAL SOLUTIONS rr City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 13 buildings, the presence of floor moisture would be considered a significant detriment to the �. tenants. If moisture control is a concern we recommend installing a membrane between the crushed rock and the basement slab to retard the migration of moisture into the slab. This function is analogous to the use of insulation to retard heat flow through exterior walls. Vapor retarders will frequently need to be perforated to install utility services. In spite of planned perforations and others that may occur inadvertently, vapor retarders will still perform their intended function of slowing the transfer of water vapor. To maximize its effectiveness, the membrane must be installed in accordance with the manufacturer's recommendations. A 6 mil polyethylene retarder is suitable if the contractor takes care not to damage or tear the material during installation. Normally, a thin sand layer is placed below 6 mil membranes to protect the retarder from excessive punctures during construction. Modern design has resulted in the creation of cost-effective concrete mixes. Such mixes are susceptible to slab curl and cracking caused by differential moisture loss in the concrete gel. A layer of sand placed above the membrane, below the slab can allow moisture to dissipate from the bottom of the slab. Alternately, it is possible to design concrete mixes that are not particularly susceptible to these problems. The use of such mixes may allow the slab to be poured directly on top of the vapor retarder. 5.9 EROSION CONTROL The near-surface silty soils at this site are highly erodible, and any exposed soil may be subject to erosion by running water. We recommend that finished cut or fill slopes be graded in accordance with Section 5.4 and be protected as soon as possible with vegetation, gravel, or other approved erosion control methods. Water should not be allowed to flow over slope faces or drop from outfalls, but should be collected and routed to the storm water disposal system. Rip-rap, gabion baskets, or similar erosion control methods may be necessary at storm water outfalls or to reduce water velocity in ditches. Silt fences should be established and maintained throughout the construction period down slope from all construction areas to protect the natural drainage channels from erosion and/or siltation. Care should be taken to maintain native vegetation and organic soil cover in as much of the site as possible. 5.10 UNDERGROUND UTILITIES & EXCAVATION +rr The owner and the contractor should make themselves aware of and become familiar with applicable local, state, and federal safety regulations, including current OHSA excavation and rr trench safety standards. Construction site safety is the sole responsibility of the contractor, who shall also be solely responsible for the means, methods, and sequencing of construction operations. AEE is providing this information solely as a service to City of Tigard. Under no circumstances should the information provided below be interpreted to mean that AEE is assuming responsibility for construction site safety or the contractor's activities; such responsibility is not implied and should not be inferred. AGRA Earth & Environmental illl ENGINEERING GLOBAL SOLUTIONS City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 14 Utility trenches are expected to be excavated within the Willamette Silt layers. The soils are expected to be easily excavatable with standard back-hoe. The Trench wall stability is expected to be poor in the silty clay to clayey silt even above the groundwater table. It should ,� . be recognized that any recommendations for slopes in soil are necessarily approximate and frequently may require adjustments in the field based on the soil type, soil moisture, and the observed behavior of soil during construction. Shoring may be necessary to restrict top width of slopes. The sides of any trench or excavation in which workers will be present, regardless of depth, should comply with local, state or federal safety regulations. Utilities should be bedded in sand within one conduit diameter in all directions before coarser backfill is placed. Trench backfill should be lightly compacted within two diameters or 18 inches, whichever is greater, above breakable conduits. The remaining backfill should be compacted to 92% of maximum density determined in accordance with ASTM D 1557. The upper foot of backfill over which pavement will be placed should be compacted to 95% of the maximum dry density determined in accordance with ASTM Test Method D 1557. Groundwater at this site is present at depths varying from approximately 10 to 12 feet below. the existing ground surface. Perched groundwater may be encountered at variable and unpredictable locations at the site. Dewatering systems are typically designed and constructed by the contractor. �r 6.0 FUTURE GEOTECHNICAL SERVICES We recommend that we be retained to review the plans and specifications when they become available. This will allow us to evaluate whether any change in concept may have affected the validity of our recommendations, and whether our recommendations have been correctly interpreted. In order to correlate preliminary soil data with the soil conditions encountered during construction, and to assess construction conformance to our report, we recommend that we be retained for construction observation of stripping, grading, compaction and all other rr soils related portions of this project. o, 7.0 LIMITATIONS The geotechnical recommendations provided in this report are based on site conditions as they r„ presently exist, and on information gathered during our field exploration, office review, and on information provided by the clients representatives. If there is a substantial lapse of time between our geotechnical exploration and the start of work at this site, or if conditions have �r changed as a result of construction or demolition, or if the project details have been significantly modified from that described herein, we recommend that we be retained to review this report to reevaluate our conclusions and recommendations. Unanticipated soil conditions are commonly encountered during construction and cannot always be determined by a normally acceptable subsurface exploration program. Such 45 AGRA Earth & Environmental ENGINEERING GLOBAL SOLUTIONS City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 15 constructed project. Therefore it is prudent to allow for such unforeseen conditions in both project schedule and construction budget. If you have any questions or desire further information, please feel free to contact the undersigned at (503) 639-3400. AGRA Earth & Environmental, Inc. r. P R Q,,-e Rajiv Ali, PhD �� G,tN� r Geotechnical Engineering Staff 13, 3') r ten, A) s A. Wesley Spang, PhD, PE =12/31/9-/Principal Geotechnical Engineer EXPIR err RA/klp rr +r ■r o AGRA Earth & Environmental aw 9620.L&R ENGINEERING GLOBAL SOLUTIONS City of Tigard - Police Building Addition 7-61 M-09620-0 Geotechnical Investigation December 4, 1997 Tigard, Oregon Page 16 wr List of References a�rr 1 . Geomatrix, "Seismic Design Mapping, State of Oregon", prepared for Oregon Department of Transportation, 1995. 2. Idriss, I.M., "SHAKE 91, A Computer Program for Conducting Equivalent Linear Seismic +rr Response Analysis of Horizontally Layered Soil Deposits", 1992. 3. Ishihara, K. and M. Yoshimine, "Evaluation of Settlements in Sand Deposits Following Liquefaction During earthquakes," Soils and Foundations, Vol 32, No. 1 , 1992. 4. Joyner, W.B., and D.M. Boore, "Prediction of Earthquake Response Spectrum", USGS Open File Report 82-977, 1982. 5. Kramer, S.L.,"Geotechnical Earthquake Engineering", Prentice Hall, 1996. 6. ODOT, "Standard Specifications for Highway Construction", 1996. 7. Oregon Department of Geology and Mineral Industries, "Geologic Map of The Portland Quadrangle, Multnomah and Washington Counties, Oregon and Clark County, Washington", 1991 . 8. Peterson, C.D., M.E. Darienzo, S.F. Burns and W.K. Burris, "Field Trip to Cascadia r Paleoseismic Evidence Along the Northern Oregon Coast: Evidence of Subduction Zone Seismicity in the Central Cascadia Margin", Oregon Geology, Volume 55, Number 5, September 1993. > 9. Seed, H.B. and I.M. Idriss, "Rock Motion Accelerograms for High Magnitude Earthquakes," EERC, University of California, Berkeley, 1969. �I 10. Seed, H.B. and P. deAlba, "Use of SPT and CPT Tests for Evaluating the Liquefaction Resistance of Sands", Use of In Situ Testing in Geotechnical Engineering, ASCE, STP No. 6, 1986. 11 . Stark, T.D. and Olson, S.M., "Liquefaction Resistance Using CPT and Field Case Histories", Jr. of Geotechnical Engineering, ASCE Vol 121 , No. 12, 1995. .r. 12. Tokimatsu, K. and H.B. Seed, "Evaluation of Settlements in Sand due to Earthquake Shaking", Jr. of Geotechnical Engineering, ASCE Vol 113, No. 8, 1987. 40 AGRA Earth & Environmental low ENGINEERING GLOBAL SOLUTIONS Wr rr LANDAU _ 3_ ST$Y VENT w6 11 N7. 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SW_N1 � L E ILTx CT w 1F511E CT w IL TA C w $ rn W i w SNAKk SPEAHE 3t L1GT ql a PE RT Sw<DUYWL CT w d `ST L BATTLER iw n°D 5 HOODVIEIk R 10800 d n 8500 8 Te100 N a "� W u. w v9cxF1ELD 4 Sw y SY KABLE` T '"uAEslrc R w KEnax Ga RED Iosco A 3 12 SW 5� E CL ray q,SLNIERa W Arose_ df KABLOW 10 sw E N (H } e 0.f`�� .vpA��'�.+DR y _ urA n w LN Q^ i HARRI S 9000 "T4�ie d 4`� 4' < T a'< allg C <2 o t) <AV, O e t YID iYll FIGURE 1 W.O. 7-61M-9620-0 TIGARD POLICE STATION EXTENSION AG R A DESIGN RA S.W. HALL BLVD. Earth &Environmental DRAWN DRF TIGARD, OREGON 7477 S.W. Tech Center Drive DATE NOV. 1997 SITE LOCATION MAP + Portland, OR, U.S.A. 97223-8025 SCALE NTS AGRA EARTH ac ENVIRONMENTAL, INC. DRAWING NO. \PROJECTS\21\09620\SITELOC.DWG wr P-2 P-3 POLICE FACILITY ADDITION P-1 EXISTING POLICE HEADQUARTERS LEGEND P-1 CONE PENETRATION TEST 0 NUMBER AND APPROXIMATE LOCATION EXISTING CITY HALL SOURCE: HANSON DUNAHUGH NICHOLSON ARCHITECTS, ENTITLED "TIGARD POLICE ADDITION AND REMODEL" DATED 9 6/96, SHEET C-1. FIGURE 2 W.O. 7-61M-9620-0 TIGARD POLICE STATION EXTENSION 0 30 60 AC3 R A DESIGN RA TIGARD OREGOLL N Earth&Environmental DRAWN DRF SCALE IN FEET 7477 S.W. Tech Center Drive DATE NOV. 1997 Portland, OR, U.S.A. 97223-8025 SCALE 1"=30' SITE PLAN AGRA EARTH & ENVIRONMENTAL. INC. DRAWING NO. \PROJECTS\21\09620\SITE.DWG Wr WALL o a e n a d 111f11 - a GRANULAR COVER + ON DRAIN APPROVED NON—WOVEN FILTER FABRIC wrr A) PERIMETER DRAIN EXTERNAL FOOTING wr 122"" I ar 15' TYP. 4" DIAMETER PERFORATED PVC i. APPROVED NON—WOVEN FILTER FABRIC OPEN GRADED ar CRUSHED ROCK OR PIT—RUN ROCK) ON B) UNDERSLAB DRAINS w FIGURE 3 to W.O. 7-61M-9620-0 TIGARD POLICE STATION EXTENSION A G R A DESIGN RA S.W. HALL BLVD. Earth&EnvironmentalDRAWN DRF TIGARD, OREGON 7477 S.W. Tech Center Drive DATE DEC. 1997 TYPICAL PERIMETER AND UNDERSLAB Portland, OR, U.S.A. 97223-8025 SCALE NTS DRAINAGE SYSTEMS AGRA EARTH & ENVIRONMENTAL, INC. DRAWING NO. \PROJECTS\21\09620\DRAINS.DWG war aw err rlr r err wr APPENDIX A �r Field Investigation eWlr Aft Irr rr Irr AGRA Earth & Environmental lay ENGINEERING GLOBAL SOLUTIONS Cone Tip Resistance(tsf) 0 100 200 300 400 0 - 10 ti 20 -- 3U 0 30 �. s CL d 40 ..... . . ...• Mow 0 -CPT- 1 50 �•� • - - CPT-2 CPT-3 60 FIGURE Al VV,O 7-61M-9620-0 TIGARD POLICE STATION EXTENSION O AG R A DESIGN RA S.W. HALL BLVD. Earth & Environmental DRAWN DRF TIGARD, OREGON 7477 S.W. Tech Center Drive DATE DEC. 1997 CONE TIP RESISTANCE VERSES DEPTH Portland, OR, U.S.A. 97223-8025 SCALE NTS AGRA EARTH & ENVIRONMENTAL, INC. DRAWING NO. \PROJECTS\21\09620\TIP.DWG Cone Sleeve Friction(tsfl 0 2 4 6 8 10 12 0 10 i ' 20 r i r 30 V. Q �L-.. . .- - - - • - 40 -CPT- 1 50 ; ..- . - - - CPT-2 •' 1 • CPT-3 I 60 r FIGURE A2 W.O. 7-61 M-9620-0 TIGARD POLICE STATION EXTENSION AG R A DESIGN RA S.W. HALL BLVD. Earth & Environmental DRAWN DRF TIGARD, OREGON 7477 S.W. Tech Center Drive DATE DEC. 1997 CONE SLEEVE FRICTION VERSES DEPTH Portland, OR, U.S.A. 97223-8025 SCALE NTS AGRA EARTH & ENVIRONMENTAL, INC. DRAWING NO. \PROJECTS\21\09620\SLEEVE.DWG rir Shear Wave Velocity(ft/sec) 0 500 1000 1500 0 wrr rr 10 20 rr� r E 30 a m O 40 rr 50 60 dw FIGURE A3 110 W.O. 7-61M-9620-0 TIGARD POLICE STATION EXTENSION AG R A DESIGN RA S.W. HALL BLVD. Earth&Environmental DRAWN DRF TIGARD, OREGON 7477 S.W. Tech Center Drive DATE DEC. 1997 SHEAR WAVE VELOCITY (CPT-2) Portland, OR, U.S.A. 97223-8025 SCALE NTS AGRA EARTH & ENVIRONMENTAL, INC. DRAWING NO. \PROJECTS\21\09620\SH EAR.DWG wr rlr APPENDIX A FIELD INVESTIGATION The field investigation was performed on November 14, 1997 and consisted of three Cone Penetration Test Soundings (CPT) at the approximate locations shown in Figure 2. Two of the CPT's were advanced to depths -of 30 feet while the third was terminated at 60 feet bgs. Shear wave velocities were measured in CPT-2 at one- meter intervals. The CPT-rig was furnished by a local subsurface exploration contractor. CPT sounding data are attached on the following pages. .�I aw AGRA Earth & Environmental ENGINEERING GLOBAL SOLUTIONS rrr ,» irr irr APPENDIX B Site Specific Seismic Response Spectra .�I tin M AGRA Earth & Environmental ENGINEERING GLOBAL SOLUTIONS err r 1.2 1 - - - Castaic(1971) — - Lake Hughes (1971) . . I � UBC, Zone 3, Soil S2 0.8 ; err c 0.6 p r � d � r• • cL4 N 0.4 � t 0.2 r wr 0 0 0.5 1 1.5 2 2.5 Time Period (sec) wr , arr r FIGURE B1 W.O. 7-61M-9620-0 TIGARD POLICE STATION EXTENSION AG R A DESIGN RA S.W. HALL BLVD. Earth&Environmental DRAWN DRF TIGARD OREGON 7477 S.W. Tech Center Drive DATE DEC. 1997 - RESPONSE SPECTRA FOR Portland, OR, U.S.A. 97223-8025 SCALE NTS CRUSTAL ZONE EARTHQUAKE AGRA EARTH & ENVIRONMENTAL, INC. DRAWING NO. \PROJECTS\21\09620\CRUST.DWG aw rr INN +IIr 0.8 0.7 - - - Olympia (1949) �� -- - Puget Sound (1965) ' 0.6 ' t 'UBC Zone 3, Soil S2 0 0.5 0.4 L ,rr y 0.3 a , rn 0.2 0.1 - wrr 0 0 0.5 1 1.5 2 2.5 Time Period (sec) �r. FIGURE B2 W.O. 7-61M-9620-0 TIGARD POLICE STATION EXTENSION AIG R A DESIGN RA S.W. HALL BLVD. Earth &Environmental DRAWN DRF TIGARD, OREGON 7477 S.W. Tech Center Drive PATE DEC. 1997 RESPONSE SPECTRA FOR rr Portland, OR, U.S.A. 97223-8025 SCALE NTS INTRAPLATE ZONE EARTHQUAKE AGRA EARTH & ENVIRONMENTAL, INC. DRAWING NO. \PROJECTS\21709620\INTRA.DWG it err wr 0.8 rrr 0.7 _ - - - - Mexico City(1985) +rr — - Synthetic EQ 0.6 UBC, Zone 3, Soil S2 as c 0.5 .2 �a err d 0.4 it, . 0.3 1 0.2 , \ I 0.1 r 0 0 0.5 1 1.5 2 2.5 Time Period (sec) rr. FIGURE B3 I� W.O, 7-61M-9620-0 TIGARD POLICE STATION EXTENSION AG R A DESIGN RA S.W. HALL BLVD. Earth&Environmental DRAWN DRF TIGARD, OREGON 7477 S.W. Tech Center Drive DATE DEC. 1997 RESPONSE SPECTRA FOR w. Portland, OR, U.S.A. 97223-8025 SCALE NTS SUBDUCTION ZONE EARTHQUAKE AGRA EARTH k ENVIRONMENTAL, INC. DRAWING NO. \PROJECTS\21\09620\SUBDUCT.DWG