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Report U GEODESIGN? t;01'20 13-(pc2f City of Tigard A• •roved Plans Date 5k / OFFICE COPY \, REPORT OF GEOTECHNICAL ENGINEERING SERVICES Proposed Grocery Store Improvements Greenway Town Center 12220 SW Scholls Ferry Road Tigard, Oregon For Regency Centers May 6, 2013 GeoDesign Project: RegencyCen-1 5-01 [DESIGN? May 6, 2013 Regency Centers 2999 Oak Road Walnut Creek, CA 94597 Attention: Mr. Rob Mokry Report of Geotechnical Engineering Services Proposed Grocery Store Improvements Greenway Town Center 12220 SW Scholls Ferry Road Tigard, Oregon GeoDesign Project: RegencyCen-1 5-01 GeoDesign, Inc. is pleased to submit our geotechnical engineering report for the proposed store improvements at the existing Lamb's Thriftway grocery store at the Greenway Town Center. Our services for this project were conducted in accordance with our proposal dated April 1 7, 2013. We appreciate the opportunity to be of service to you. Please call if you have questions regarding this report. Sincerely, GeoDesign, Inc. / ulio C. V_ a, Ph.D., P.E., G.E. • '- -'.. ngineer )CV:kt Attachments Two copies submitted Document ID: RegencyCen•1 5.01-050613-geor.docx <�201 3 GeoDesign,Inc. All rights reserved. 15575 SW Sequoia Pkwy,Suite 100 I Portland,OR 97224 1 503.968.8787 www.geodesigninc.com TABLE OF CONTENTS PAGE NO. 1 .0 INTRODUCTION 1 2.0 RELIANCE INFORMATION 1 3.0 PURPOSE AND SCOPE 1 4.0 SITE CONDITIONS 2 4.1 Geologic Setting 2 4.2 Seismic Setting 3 4.3 Surface Conditions 3 4.4 Subsurface Conditions 3 5.0 CONCLUSIONS AND RECOMMENDATIONS 4 5.1 General 4 5.2 Site Preparation 4 5.3 Construction Considerations 5 5.4 Excavation Considerations 6 5.5 Structural Fill 7 5.6 Shallow Foundations 9 5.7 Resistance to Sliding 10 5.8 Floor Slabs 10 5.9 Seismic Considerations 11 6.0 SUPPLEMENTAL INFORMATION 11 7.0 OBSERVATION OF CONSTRUCTION 12 8.0 LIMITATIONS 12 FIGURES Vicinity Map Figure 1 Site Plan Figure 2 APPENDIX Field Exploration A-1 Laboratory Testing A-1 Exploration Key Table A-1 Soil Classification System Table A-2 Boring Logs Figures A-1 -A-4 ACRONYMS MDESI G N'- RegencyCen-15-01:050613 1.0 INTRODUCTION This report presents the results of GeoDesign's geotechnical engineering evaluation of the proposed grocery store improvements located in the Greenway Town Center in Tigard, Oregon. The project site is located within an overall 7.64-acre retail development constructed in 1979. The portion of the site considered for this project is the existing Lamb's Thriftway in the south- central portion of the site. The existing store is noted as the Unified Western Grocers building in site plans included in the information provided to us by Regency Centers. The project includes upgrades to the existing store shell. This report presents the results of our on-site subsurface explorations and surface pavement observations and our evaluation and recommendations related to proposed store development and suitability of the existing building and parking areas relative to proposed design requirements. The site is located at 12220 SW Scholls Ferry Road in Tigard, Oregon. The overall site is bound on the north by SW Scholls Ferry Road, on the east by SW 12155 Avenue, and on the south by Springwood Drive. Access drives to the shopping center are located off of all three boundary roads. Based on the site development information provided by Regency Centers, store development will be located within the former Lamb's Thriftway store. Figure 1 shows the site location relative to surrounding physical features. Figure 2 shows the approximate site boundaries, store location and parking layout, and approximate exploration locations. For your reference, definitions of acronyms used herein are defined at the end of this document. 2.0 RELIANCE INFORMATION In preparing this report, we have relied on information provided to us by Regency Centers, including a property condition assessment report prepared by EMG of Hunt Valley, Maryland; our experience in the local vicinity; as well as published geologic information. In addition, Mr. Mokry provided verbal and email information regarding proposed site development. 3.0 PURPOSE AND SCOPE The purpose of our services was to consider subsurface soil and groundwater conditions at the site to provide the basis for geotechnical opinion regarding the suitability of the site for the proposed re-development and to provide geotechnical engineering recommendations for use in additional design and construction of the proposed development. Specifically, our suitability study is to consider subsurface conditions and geotechnical issues for evaluation of the existing building and proposed improvements. We completed the following scope of services in accordance with our April 1 7, 2013 proposal for services: =DESIGN:, 1 RegencyCen-1 5-01:05061 3 • Coordinated and managed the field investigation, including locating utilities and scheduling our subcontractors and GeoDesign field staff. • Provided recommendations for limited site preparation adjacent to the building where limited demolition of hardscapes or pavement may occur, including general grading and drainage, compaction criteria for both on-site and imported material, fill type for imported material, procedures for use of on-site soil, and wet weather earthwork procedures in case larger areas are exposed. • Provided geotechnical engineering recommendations for evaluation of existing foundation or design of supplemental foundations to be used for support of proposed improvements. • Provided recommendations shallow foundations. Our recommendations include allowable bearing capacity, settlement, and lateral resistance parameters. • Provided recommendations for preparation of floor slab subgrade. • Provided recommendations for the management of identified groundwater conditions that may affect the performance of structures or pavement. • Provided a discussion of seismic activity near the site and recommendations for seismic design factors in accordance with the procedures outlined in the 2010 SOSSC and IBC. • Prepared a final report of our explorations, findings, conclusions, and recommendations 4.0 SITE CONDITIONS 4.1 GEOLOGIC SETTING The site is located in the Tualatin Basin of the Puget Sound-Willamette Valley physiographic province, a tectonically active lowland located along the convergent Cascadia. The lowland is generally an elongated alluvial plain bordered on the west by the Coast Ranges and on the east by the Cascade Mountains. The Tualatin Basin is formed by a gentle syncline between the uplifted Coast Ranges to the west and the uplifted Tualatin Mountains to the northeast. The Tualatin Mountains have been uplifted along northwestern-oriented faults, including the steeply dipping Portland Hills Fault, located along the eastern flank of the mountains. Basement rocks of the Tualatin Basin are exposed in the highlands surrounding the valley, which primarily consist of volcanic and sedimentary rocks several millions of years old, including the CRBs. The CRBs consist of thick flows of basalt erupted from fissures in eastern Oregon, Washington, and western Idaho that traveled down the ancient Columbia River Gorge to fill areas of the lowland around Portland and the surrounding vicinity. These were later folded and faulted from the compressional tectonics of the region. Following the structural disruption of the CRBs, alluvial mudstones accumulated in the Portland and Tualatin basins in a large delta where the ancient Columbia River and Willamette River converged. Around the Tualatin Mountains, the mudstones have been referred to as the Sandy River Mudstone equivalent or Neogene mudstones by different sources. The most recent major geologic events to shape the region were tremendous floods down the Columbia River, caused by the collapse of glacial dams and drainage of large lakes in western Montana. Many dozens of these Missoula Floods occurred between approximately 1 5,500 and 12,500 years ago (and perhaps during earlier glaciations). Flood waters several hundred feet deep swept out of the Columbia Gorge and over the lowlands of the Portland area, reshaping the surfaces and depositing fresh sediments over the terraces. CIDESIGN= 2 RegencyCen-1 5-01:050613 In most of the Tualatin Basin, fine-grained sand, silt, and clay were deposited by the flood waters in temporary lakes formed in the valley. Prior to and along with the flooding events, wind-blown silt and clay derived from glaciers to the north, referred to as loess, were deposited on the hills surrounding the Portland area. Where flood waters did not scour the hillsides in the Portland and Tualatin basins, generally higher than approximately 400 feet above MSL, loess deposits are still preserved. In the periods between and following the Missoula Floods, the Columbia, Willamette, and Tualatin rivers and their tributaries eroded down through the loose sediment to re-establish their channels. The thickness of alluvial deposits in the area generally varies but can be expected to be 30 feet thick or more in larger flood plains. Geologic maps indicate an alluvial thickness of up to 90 feet in the area of the site. This unit typically is susceptible to erosion, especially when exposed on steep slopes. Perched and relatively shallow groundwater may also be present. In addition, based on topographic maps of the region, the site is located in a relatively low-lying area near the foothills of the west hills of Portland where outwash accumulations could form. Basement contour maps indicate an approximate depth of 650 feet to contact with bedrock. 4.2 SEISMIC SETTING Oblique subduction of the Juan de Fuca Plate beneath the North American Plate is occurring along the margin and represents a variety of earthquake hazards to the Pacific Northwest. The Portland metropolitan area has not experienced an earthquake greater than magnitude M 6 in historic time, but six magnitude M 5+ earthquakes have occurred during the last 150 years. In 1993, a magnitude M 5.3 earthquake occurred near the town of Scotts Mills, approximately 35 miles south of the site. The Tualatin Basin and surrounding area have several northwest-striking faults that have been identified below sedimentary cover and mapped in exposed bedrock, including within the CRBs of the Tualatin Mountains. The faults are related to the northwest-trending, right-lateral fault system that dominates the region. One of these faults, the Portland Hills Fault, runs along the eastern flank of the Tualatin Mountains and is located approximately 5 miles northeast of the site. The fault is generally considered to be a steeply dipping fault with components of both strike-slip motion and vertical motion. The Portland Hills Fault is considered to have a relatively high probability of activity based on differences in subsurface sediment thickness, the sharp topographic expression of the northeastern face of the Tualatin Mountains, and recent evidence of sediment offset and fault activity near the inferred trace of the fault. 4.3 SURFACE CONDITIONS At the time of our explorations, the site was occupied by an active shopping center. The structures consist of a concrete and masonry block buildings with generally at-grade walls. The primary entrance is located at the north side of the store building with receiving doors on the south wall. The interior of the store is slab on grade concrete slab. The exterior area consists of concrete apron and sidewalk areas adjacent to AC-paved parking. 4.4 SUBSURFACE CONDITIONS We explored subsurface conditions in the project area by drilling four exploratory borings (B-1 through B-4). We did not conduct core explorations on the building interior or floor slab. The [ •DESIGN=- 3 RegencyCen-1 5-01:05061 3 details of the exploration program, exploration logs, and a summary of laboratory testing are provided in the Appendix. The approximate locations of the explorations are shown on Figure 2. Soil underlying the exterior of the building generally consists of medium stiff to stiff silt with varying amounts of sand. The silt soil generally grades with more fine sand and increasing stiffness with depth The pavement section generally consists of 2 Y2 inches of AC over 6 inches of compacted crushed base rock. Some thicker sections of AC were observed as noted on the boring logs but are likely isolated to the areas where fine grading was limited by site restrictions during original construction. The existing pavement section is likely on the order of 2 %z inches of AC over 6 inches of base rock as noted. The base rock is generally underlain by medium stiff silt. Groundwater, interpreted to represent a regional groundwater table, was typically encountered at a depth of 11 to 16 feet BGS in the borings. Water levels can be expected to vary at the site, depending on seasonal and regional changes, but are anticipated to be as shallow as 5 to 8 feet BGS following peak periods of rainfall. Other factors not evident during our subsurface exploration may also influence groundwater levels. 5.0 CONCLUSIONS AND RECOMMENDATIONS 5.1 GENERAL We evaluated geotechnical elements of the existing development based on our observations, as well as our experience with similar projects in the site area. The following sections present our conclusions for geotechnical-specific design elements. Depending on the structural engineer's evaluation and application of current seismic design parameters, additional work may be required to evaluate structural elements. Reports indicate that there is no obvious cracking or structural distress. The existing pavement section is in generally serviceable condition but has areas of cracking and surface spalling and breakup damage. The general existing pavement section thickness is generally suitable for support of standard-duty traffic but may be inadequate to support heavy- duty traffic, depending on the required use and traffic loading patterns. The existing structural components of the building should be evaluated by a structural engineer. The recommendations given in the following sections are intended for evaluating specific elements of the existing structure, as well as for subsequent design or retrofit design relative to specific geotechnical issues. 5.2 SITE PREPARATION Site development that includes rehabilitation or reconstruction of the existing paved areas will require demolition and removal of existing improvements. Existing utilities may be present across the site. Existing utilities that will interfere with earthwork or will be located beneath any proposed structural addition should be removed and/or relocated prior to construction. Abandoned utilities will need to be removed or grouted full if left in place. Also, previous development may include undocumented fill or abandoned subsurface structural elements that [OIRDESIG N= 4 RegencyCen-1 5-01:05061 3 may not have been encountered during our explorations. If encountered during construction, these structural elements or undocumented fill should be excavated and removed or backfilled in accordance with project specifications. Depending on the extent of development, demolition of existing improvements may include complete removal of hardscape structural features and floor slabs, asphalt pavement, landscaping and landscape features, abandoned utilities, and previous construction debris. The base course for the existing pavement and likely under the floor slab can be separated from underlying material and stockpiled for use as fill if it meets the requirements but may not be suitable to be used as base course for new pavement or concrete slabs if it contains excessive amounts of fines or deleterious material. Demolished concrete and AC materials may be used in structural fill provided it meets the requirement outlined in the "Structural Fill" section of this report. Demolished material that has not been processed for use as structural fill should be transported off site for disposal. Excavations from demolition of existing development should be backfilled with compacted structural fill as recommended in this report. The bottoms of the excavation should be excavated to expose firm subgrade. The sides of the excavations should be cut into firm material and sloped a minimum of 1 H:1 V. Excavations should not undermine adjacent foundations, walkways, streets, or other hardscapes unless special shoring or underpinning is provided. Excavations should not be conducted within an outward and downward projection of a 1 H:1 V line starting at least 2 feet outside the edge of an adjacent structural feature. After stripping, demolition, and required site preparation have been completed, we recommend the subgrade be evaluated by a qualified geotechnical engineer or their representative. If unsuitable areas are identified, the material should be excavated and replaced with compacted material recommended for structural fill. Areas that appear to be too wet and soft to support construction equipment should be prepared in accordance with the recommendations presented in the following section of this report. 5.3 CONSTRUCTION CONSIDERATIONS The fine-grained, near-surface soil on site is easily disturbed and difficult to compact when wet. If not carefully executed, site preparation in exposed excavation can create extensive soft areas and significant repair costs can result. Earthwork planning and construction should include considerations for minimizing subgrade disturbance. Proofrolling of subgrade should not be performed during wet weather or if wet ground conditions exist. Instead, the subgrade should be evaluated by probing. Soil that has been disturbed during site preparation activities, or soft or loose zones identified during probing, should be removed and replaced with structural fill. Site grading and fill placement for reconstruction can proceed during wet conditions provided the following recommendations are applied. Generally, stripping and site preparation should be accomplished using track-mounted equipment and modified construction methods. For example, a track-mounted excavator equipped with a smooth-edged bucket could be used working from the existing paved surface or underlying base course surface or a granular pad and MEIDESIGW 5 RegencyCen-15-01:050613 loading into trucks supported on granular haul roads or similar surface. While the exposed subgrade is wet, the subgrade should be evaluated by probing with a steel rod, rather than by proofrolling. Soil that is disturbed during site preparation activities during wet conditions, as well as soft or loose zones identified during probing, should be removed and replaced with compacted structural fill. Existing pavement sections may not be adequate to support repeated heavy construction traffic in all areas. Careful planning is required by the site contractor to vary site construction traffic patterns and to protect the existing AC section from damage by construction vehicles. 5.4 EXCAVATION CONSIDERATIONS 5.4.1 Temporary Slopes Based on soil conditions encountered during our explorations, temporary slopes for excavation of 1.5H:1 V may be used to vertical depths of 8 feet or less, provided groundwater seepage is not encountered and groundwater remains below the base of the excavation. At this inclination, unprotected slopes may slough at the surface and require some on-going repair. If seepage is encountered, it will be necessary to flatten the slopes to protect the surface from sloughing or provide dewatering. All cut slopes should be protected from erosion by covering them with plastic sheeting or other stabilizing cover during the rainy season. If sloughing or instability is observed, the slope may need to be flattened or the cut supported by shoring. Excavations should not undermine adjacent utilities, foundations, walkways, streets, or other hardscapes unless special shoring or underpinned support is provided. Unsupported excavations should not be conducted within a downward and outward projection of a 1 H:1 V line from 2 feet outside the edge of an adjacent structural feature. 5.4.2 Trench Cuts and Shoring Trench cuts should stand vertical to a depth of approximately 4 feet, provided groundwater seepage is not observed in the trench walls. Open excavation techniques may be used to excavate trenches with depths between 4 and 8 feet, provided the walls of the excavation are cut at a slope of 1 .5H:1 V and groundwater seepage is not present. Sloughing conditions will likely occur if the excavation extends below the groundwater table or during extended periods of wet weather. The walls of the trench should be flattened or braced for stability and a dewatering system installed if seepage is encountered. Use of a trench box or other approved temporary shoring is recommended for cuts below where groundwater seepage is observed. If shoring is used, we recommend that the type and design of the shoring system be the responsibility of the contractor, who is in the best position to choose a system that fits the construction plan. 5.4.3 Dewatering We did not observe groundwater near the surface in our explorations. During extended periods of wet weather, or if perched groundwater seepage is encountered, dewatering may be necessary in foundation and utility trench excavations. We recommend that if dewatering becomes necessary, that it be accomplished by pumping from sumps on an as-needed basis. Based on the proposed development, observed groundwater conditions, and the nature of the near-surface [DESIGN= 6 RegencyCen-15-01:05061 3 soil, it is our opinion that wide-scale dewatering from wells or well points should not be required. A more intensive use of sumps may be required in excavations during wet weather, or excavations that cut into perched groundwater locations. Dewatering water should be pumped to a suitable disposal point. Because of varying site topography that typically occurs during construction, uncontrolled dewatering effluent may return to the excavation or lead to inappropriate disposal points if not effectively disposed. If excessive groundwater is present in the base of trench excavations and stabilization becomes necessary, we recommend over excavating the trench by 6 inches and placing trench stabilization material in the base. Trench stabilization material should consist of well-graded gravel, crushed gravel, or crushed rock meeting the requirements outlined in the "Structural Fill" section of this report. Trench stabilization material should be placed in one lift and compacted until well keyed. 5.4.4 Safety All excavations should be made in accordance with applicable OSHA and state regulations. While we have described certain approaches to the utility vault and trench excavations in the foregoing discussions, the contractor is responsible for selecting the excavation and dewatering methods, monitoring the trench excavations for safety, and providing shoring as required to protect personnel and adjacent improvements. 5.5 STRUCTURAL FILL 5.5.1 General Fill should only be placed over a subgrade that has been prepared in conformance with the "Site Preparation" section of this report. All material used as structural fill should be free of organic matter or other unsuitable material. The material should meet the specifications provided in OSSC 00330 (Earthwork), depending on the application. All structural fill should have a maximum particle size of 3 inches. A brief characterization of some of the acceptable materials and our recommendations for their use as structural fill is provided below. 5.5.2 Recycled Material Demolished concrete, AC, and base rock material may be used as structural fill, provided it can be processed or crushed to a maximum particle size of 3 inches; is well graded; is free of metal, debris, or other deleterious material; and is placed no shallower than 1 foot below final subgrade elevation. The material should be placed in lifts with a maximum uncompacted thickness of 12 inches and compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D 1557. 5.5.3 On-Site Upper Silt If use of the on-site material as structural fill is attempted, the fill material should meet the requirements set forth in OSSC 00330.12 (Borrow Material). However, the moisture content of the on-site material is significantly higher than that required for compaction and considerable drying will be required to process this material for use as structural fill. Based on the limited space available to spread and dry the on-site material, it is unlikely that the on-site soil can be DESIGN:, 7 RegencyCen-1 5-01:050613 adequately processed for use as structural fill, and we recommend a contingency be in place to export cut material from the site and import structural fill to raise site grades and for proposed site fills. When used as structural fill, the on-site soil should be placed in lifts with a maximum uncompacted thickness of 8 inches and compacted to not less than 92 percent of the maximum dry density, as determined by ASTM D 1 557. 5.5.4 Imported Granular Material Imported granular material used for structural fill should be pit- or quarry-run rock, crushed rock, or crushed gravel and sand and should meet the requirements set forth in OSSC 00330.14 (Selected Granular Backfill) and OSSC 00330.1 5 (Selected Stone Backfill). Imported granular material should be fairly well graded between coarse and fine material, have less than 5 percent by dry weight passing the U.S. Standard No. 200 Sieve, and have at least two mechanically fractured faces. When used as structural fill, imported granular material should be placed in lifts with a maximum uncompacted thickness of 12 inches and compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D 1 557. 5.5.5 Floor Slab Base Rock Imported granular material placed beneath building floor slabs should be clean crushed rock or crushed gravel and sand that is fairly well graded between coarse and fine. The granular material should have a maximum particle size of 1 Y2 inches, less than 5 percent by dry weight passing the U.S. Standard No. 200 Sieve, have at least two mechanically fractured faces, and should meet OSSC 00641 (Aggregate Subbase, Base, and Shoulders). The imported granular material should be placed in one lift and compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D 1 557. 5.5.6 Pavement Base Rock If improvements or expansions are considered for paved areas, imported granular material used as base rock for pavements should consist of 3/4- or 1%z-inch-minus material meeting the requirements in OSSC 00641 (Aggregate Subbase, Base, and Shoulders), with the exception that the aggregate has less than 5 percent by dry weight passing the U.S. Standard No. 200 Sieve and at least two mechanically fractured faces. The imported granular material should be placed in lifts with a maximum uncompacted thickness of 12 inches and compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D 1557. 5.5.7 Trench Backfill Trench backfill for the utility pipe base and pipe zone should consist of well-graded granular material with a maximum particle size of 1 inch and less than 5 percent by dry weight passing the U.S. Standard No. 200 Sieve and should meet OSSC 00405.14 (Trench Backfill, Class B). The material should be free of roots, organic matter, and other unsuitable material. Backfill for the pipe base and pipe zone should be compacted to at least 90 percent of the maximum dry density, as determined by ASTM D 1557, or as recommended by the pipe manufacturer. [OIRDESIGNP 8 RegencyCen-1 5-01:050613 Within building, pavement, and other structural areas, trench backfill placed above the pipe zone should consist of imported granular material as specified above. The backfill should be compacted to at least 92 percent of ASTM D 1 557 at depths greater than 2 feet below the finished subgrade and 95 percent of ASTM D 1557 within 2 feet of finished subgrade. In all other areas, trench backfill above the pipe zone should be compacted to at least 92 percent of the maximum dry density, as determined by ASTM D 1 557. 5.5.8 Trench Stabilization Material Trench stabilization material should consist of pit- or quarry-run rock, crushed rock, or crushed gravel and sand and should meet the requirements set forth in OSSC 00330.14 (Selected Granular Backfill) and OSSC 00330.1 5 (Selected Stone Backfill), with a minimum particle size of 6 inches and less than 5 percent by dry weight passing the U.S. Standard No. 4 Sieve. The material should be free of organic matter and other deleterious material. Trench stabilization material should be placed in one lift and compacted to a firm condition. 5.5.9 Drain Rock Drain rock should consist of angular, granular material with a maximum particle size of 2 inches and should meet OSSC 00430.11 (Granular Drain Backfill Material). The material should be free of roots, organic matter, and other unsuitable material and have less than 2 percent by dry weight passing the U.S. Standard No. 200 Sieve (washed analysis). 5.6 SHALLOW FOUNDATIONS We have not been provided information relative to initial site preparation or as-built footing sizes or locations of the existing structure. However, based on local construction practice, the existing building is most likely supported on continuous wall or isolated column footings. Subsurface explorations indicate that the soil in the shallow foundation zone is competent native silt soil that appears to be adequately prepared. In addition,we did not observe excessive floor slab cracking that would indicate excessive foundation settlement. The existing foundations should be reviewed for adequate bearing, settlement, and lateral resistance using the recommended values presented in the following paragraphs. These design values are based on limited information regarding the existing structure and a limited number of explorations and are considered conservative. For instance, it may be possible to increase the allowable bearing capacity based on further study of the preloading effect of the existing foundations. For more critical elements, we can consult with the structural engineer to discuss the sensitivity and range of values for specific design recommendations. When evaluating loads from the existing structure or evaluating loads from a renovated structure, continuous wall and spread footings for the existing footing loads should be proportioned for an allowable bearing pressure of 2,500 psf and should be at least 18 and 24 inches wide, respectively. The bottom of exterior footings should be at least 18 inches below the lowest adjacent final grade. The bottom of interior footings should be placed 12 inches below the bottom of the floor slab. CDESIGN' 9 RegencyCen-1 5-01:050613 The recommended allowable bearing pressure applies to the total of dead plus long-term live loads. The allowable bearing pressure may be increased by up to one-half for short-term loads, such as those resulting from wind or seismic forces. Total settlement of footings founded as recommended is anticipated to be less than 1 inch. Differential settlement is estimated at one-half of the total settlement. 5.7 RESISTANCE TO SLIDING Lateral loads on footings can be resisted by passive earth pressure on the sides of footings and by friction on the base of the footings. Our analysis indicates that the available passive earth pressure for footings confined by structural fill or for footings constructed in direct contact with the native soil is 300 pcf. Typically, the movement required to develop the available passive resistance can be relatively large. Therefore, we recommend using a reduced passive pressure of 250 pcf. This value is based on the assumptions that the adjacent confining structural fill or native material is level and that static groundwater remains below the base of the footing throughout the year. Adjacent floor slabs, pavements, or the upper 12-inch depth of adjacent unpaved areas should not be considered when calculating passive resistance. We recommend a friction coefficient of 0.30 for footings. The passive earth pressure and friction components may be combined provided that the passive component does not exceed two-thirds of the total. The top foot of soil should be neglected when calculating passive lateral earth pressures, unless the foundation area is covered with pavement or is inside the building. The lateral resistance values do not include safety factors. We recommend a safety factor of 2 when designing for dead loads plus frequently applied live loads and a safety factor of 1.5 when considering transitory loads such as wind and seismic forces. 5.8 FLOOR SLABS We do not have information with respect to the existing floor section thicknesses. Based on our explorations and on site observations, the underlying subgrade should provide adequate support for design floor loads typical for this type of development, provided the overlying floor section is structurally capable. A qualified structural engineer should conduct appropriate structural evaluation of the existing slab. If the existing floor slab thickness does not meet structural design requirements, remedial options include the following: • Demolish the existing slab and construct a floor section to meet the structural design requirements. If this option is employed, we recommend replacing and compacting a minimum 6-inch-thick crushed rock base section under the new slab. The crushed rock should meet the requirements for floor slab base rock, as provided in the "Structural Fill" section of this report. • Construct a new floor slab over the existing slab if it is deemed viable by a structural engineer. • A modulus of subgrade reaction of 200 pci can be used for the compacted crushed rock base to evaluate the existing floor slab and for design of new slabs. C DESIGN: 10 RegencyCen-15-01:050613 Settlement for newly constructed floor slabs is estimated to be less than %Z inch for a distributed floor load of 200 psf or less. 5.9 SEISMIC CONSIDERATIONS We recommend that the development be evaluated in accordance with the current version of the IBC. The parameters provided in the table below are appropriate for code-level seismic design and should be used to evaluate the seismic capacity of the existing structure. IBC Seismic Design Parameters Parameter Short Period 1 Second Maximum Considered Earthquake Spectral Acceleration SS= 0.93 g S, = 0.34 g Site Class D Site Coefficient F = 1.13 F = 1.73 Adjusted Spectral Acceleration SMS= 1.05 g SM, = 0.59 g Design Spectral Response Acceleration Parameters 0.70 g 0.39 g Design Spectral PGA 0.28 g Liquefaction settlement is the result of seismically induced densification and subsequent ground deformation. Based on our analysis for this investigation,the site soil is not expected to liquefy in a design earthquake. Accordingly, lateral spreading is not expected. 6.0 SUPPLEMENTAL INFORMATION The information presented in this report is intended for an evaluation of the geotechnical suitability of an existing facility. Where the evaluation shows that geotechnical elements of the existing structure are not adequate or the adequacy is unclear, additional studies may be warranted. We can be contacted to discuss an approach to further studies if required. The following list is intended to provide example studies that may provide additional information for evaluating the building and site: • Detailed survey information. Detailed survey information can be used to supplement structural observations. At this site, no observable building distress has been reported; therefore, additional survey may not be required. • Floor slab/pavement cores. Cores in the floor slab and pavement could be used to further define the section thicknesses and/or check areas that will be subjected to higher loads or that appear to be only marginally distressed. • Existing structural elements should be evaluated by a structural engineer relative to the design information presented in this report. MINDESIGW 11 RegencyCen-15-01:050613 7.0 OBSERVATION OF CONSTRUCTION Satisfactory foundation and earthwork performance during construction depends to a large degree on quality of construction. Sufficient observation of the contractor's activities is a key part of determining that the work is completed in accordance with the construction drawings and specifications. Subsurface conditions observed during construction should be compared with those encountered during the subsurface exploration. Recognition of changed conditions often requires experience; therefore, qualified personnel should visit the site with sufficient frequency to detect if subsurface conditions change significantly from those anticipated. We recommend that GeoDesign be retained to observe earthwork activities, including site preparation, proofrolling of the subgrade and repair of soft areas, performing laboratory compaction testing and field moisture-density tests, observing final proofrolling of the pavement subgrade and base rock, and asphalt placement and compaction. 8.0 LIMITATIONS We have prepared this report for use by Regency Centers and the design and construction team for specific application in the design and evaluation of the proposed project. Any use of this report by others, or for purposes other than intended, is at the user's sole risk. The data and report can be used for bidding or estimating purposes, but our report, conclusions, and interpretations should not be construed as warranty of the subsurface conditions and are not applicable to other sites. Exploration observations indicate soil conditions only at specific locations and only to the depths penetrated. They do not necessarily reflect soil strata or water level variations that may exist between exploration locations. If subsurface conditions differing from those described are noted during the course of excavation and construction, re-evaluation will be necessary. The scope of our services does not include services related to structural elements, construction safety precautions, and our recommendations are not intended to direct the contractor's methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design. Within the limitations of scope, schedule, and budget, our services have been executed in accordance with generally accepted practices in this area at the time the report was prepared. No warranty, express or implied, should be understood. MIC DESIGN, RegencyCen-15-01:050613 We appreciate the opportunity to be of service to you. Please call if you have questions concerning this report or if we can provide additional services. Sincerely, GeoDesign, Inc 1,�� aG NEc�. A •033: •' GON o0 ulio C. Ve :, Ph.D., P.E., G.E. � �, s ti�Q. •• Engineer /O c �� EXPIRES: 6/30/14 GEODES I G 13 RegencyCen-15-01:050613 FIGURES .. c t L,•�♦ ..1Z "f. ,.�r .yn4- .• i S ,_Y _ �L Y -n , JCr� 4%44.f S't - _ • ' �{}ice Y+` r r 7 .I ■ :..1":0,...:1t.-. �.r l .,i.r, ... ..... ,.... . , _ .tt „ t = :0;,%02,1:1-.! ... ` - ' 7}•'1 ^t 4,�\d.r•1 M ' ` ,,,•,.I•^ .1� ._._,•:-..'TZ _ of Ff��•• :,. .L.3 r i :--7 t :f� ' 't '• .i�l'RI• ;T.r : .4._...).4.,,r,. 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' r N N.• rn ,K r 1 ..0 (...A.) ,. 1,1 Ce f ' ■ r :.r '`'; 0 2000 4000 ▪ VICINITY MAP BASED ON AERIAL r ~r,.., • r L ,. ; 1 3 PHOTOGRAPH OBTAINED FROM ::1 {. E c GOOGLE EARTH PRO' '.-7"- - i 'S W G aard� (SCALE IN APPROXIMATE FEET) c 4) - v • G EODESIGN? REGENCYCEN-15-01 VICINITY MAP m E 15575 SW Sequoia Parkway-Suite 100 71 aa Z Portland OR 97224 MAY 2013 PROPOSED GROCERY STORE IMPROVEMENTS FIGURE 1 c w Off 503.968.8787 Fax 503.968.3068 TIGARD,OR ti . '1/4.-11.11.!..-q—d A-4 11 vez-lit. .11..., ,,,/ .11 A,..,,,L.1.1:1 1 1...:41%.. 12220 S.W. SCHOLLS FERRY ROAD - TIGARD, OREGON 97223 WOOD DRIVE _ . _. ........ •-• — .:1 k. - pRei,E, . . . . .. -1 B-4 G13 i .... ::,.:7 r )-7;".UNIFIED WESTERN GROCERS RITE AID U S A BABY 0 ® 0 ...-- ...'...." ' 1 1.....- , ...- ,.. • 1 ,. . . -----1 0130 ...- — _ .. 1 . ■ 1 ( ‘ ... # ..„....--":; ---s, \ I N ... ......<:., ,,. .\\.•)u.lp 1121 -t.‘1.... CP.... ' '•,,.. is.j i 0 1 ! ‘...: t.:11 r %.1-%' 'ir: ::).. -;'4..'••• --' e".. ,-*4. • . % ••• -er.--0 '•-•:1*--":- --...• .. '4.- 8-2 , j.,..."0 - :-... ...,',......: ® i -.1 I 1 - '• ' N--t,'• -- :"- ..-i-') (.4.....) . — 0•1 ,.: ...c.. • ...... CI:- -..."`,... ____ ''...t. . „.. ,'..... ',N. ... ,- ; •..".‘,. • L- .-• ,..0 , I.- --. -...--- — •—•— —• - - ',.... ._ e : • ....e •.*. !'... --"' c‘,„I.,' • • ) .., . • • .1•.:-.. '.-.i•''. ...-+ % ." • •' .... r ,. _ ..... ...... - C. --. •••-..'.--. .- ... -.--i ',... . .--- .- II 0 01301 it •... ...... ,..., . ...., .._ ".„.. -;„• :...,..11.....: . O. 'le 3 l'...... .... de." :`... ....• ,. I . •A - .. ••• ..:•. ... . ...' ......, ...e _.., !; .r 4.„. ...,... I 0 Cr' **"... ..., ..... L' '- i ei J • .. _...„-, old- -- scHOUS i A, ..,---••* S Vi 6 +1 P 0 1( [ i APPENDIX APPENDIX FIELD EXPLORATIONS We explored subsurface conditions by drilling four exploratory borings (B-1 through B-4). Explorations were advanced to depths ranging between 16.5 and 21 .5 feet BGS. Drilling services were provided by Western States Drilling of Hubbard, Oregon. The borings were drilled using hollow-stem auger and mud-rotary drilling techniques on April 24, 2013. The locations of the explorations were determined in the field pacing from existing physical features and should be considered accurate only to the degree implied by the methods used. A member of our geotechnical staff observed the explorations. We obtained representative samples of the various soil encountered in the explorations for geotechnical laboratory testing. Classifications and sampling intervals are shown on the exploration logs included in this appendix. SOIL SAMPLING Soil samples were obtained from the borings using the following methods: 1. SPTs were performed in general conformance with ASTM D 1586. The sampler was driven with a 140-pound hammer free-falling 30 inches. The number of blows required to drive the sampler 1 foot, or as otherwise indicated, into the soil is shown adjacent to the sample symbols on the boring logs. Disturbed samples were obtained from the split barrel for subsequent classification and index testing. 2. Relatively undisturbed samples were obtained using a standard Shelby tube in general accordance with ASTM D 1587, the Standard Practice for Thin-walled Tube Sampling of Soils. SOIL CLASSIFICATION The soil samples were classified in accordance with the "Exploration Key" (Table A-1) and "Soil Classification System" (Table A-2),which are included in this appendix. The exploration logs indicate the depths at which the soil or its characteristics change, although the change actually could be gradual. If the change occurred between sample locations, the depth was interpreted. Classifications and sampling intervals are shown on the exploration logs in this appendix. LABORATORY TESTING CLASSIFICATION AND MOISTURE CONTENT The soil samples were classified in the laboratory to confirm field classifications. The laboratory classifications are included on the exploration logs if those classifications differed from the field classifications. nrIDESIGW A-1 RegencyCen-15-01:050613 We tested the natural moisture content of selected soil samples in general accordance with ASTM D 2216. The natural moisture content is a ratio of the weight of the water to soil in a test sample and is expressed as a percentage. The moisture contents are included on the exploration logs presented in this appendix. LDESIG N= A-2 RegencyCen-15-01:050613 • SYMBOL SAMPLING DESCRIPTION II Location of sample obtained in general accordance with ASTM D 1 586 Standard Penetration Test with recovery 11 Location of sample obtained using thin-wall Shelby tube or Geoprobe® sampler in general accordance with ASTM D 1587 with recovery 1 Location of sample obtained using Dames & Moore sampler and 300-pound hammer or pushed with recovery 1 Location of sample obtained using Dames & Moore and 140-pound hammer or pushed with recovery 1 Location of sample obtained using 3-inch-O.D. California split-spoon sampler and 140-pound hammer NLocation of grab sample Graphic Log of Soil and Rock Types :• Observed contact between soil or — Rock coring interval rock units (at depth indicated) V Water level during drilling Inferred contact between soil or rock units (at approximate depths indicated) IF Water level taken on date shown GEOTECHNICAL TESTING EXPLANATIONS ATT Atterberg Limits PP Pocket Penetrometer CBR California Bearing Ratio P200 Percent Passing U.S. Standard No. 200 CON Consolidation Sieve DD Dry Density RES Resilient Modulus DS Direct Shear SIEV Sieve Gradation HYD Hydrometer Gradation TOR Torvane MC Moisture Content UC Unconfined Compressive Strength MD Moisture-Density Relationship VS Vane Shear OC Organic Content kPa Kilopascal P Pushed Sample ENVIRONMENTAL TESTING EXPLANATIONS CA Sample Submitted for Chemical Analysis ND Not Detected P Pushed Sample NS No Visible Sheen PID Photoionization Detector Headspace SS Slight Sheen Analysis MS Moderate Sheen ppm Parts per Million HS Heavy Sheen G EO DESIG Nz EXPLORATION KEY TABLE A-1 15575 SW Sequoia Parkway-Suite 100 Portland OR 97224 Off 503.968.8787 Fax 503.968.3068 RELATIVE DENSITY - COARSE-GRAINED SOILS . Relative Density Standard Penetration Dames& Moore Sampler Dames& Moore Sampler Resistance (140-pound hammer) (300-pound hammer) Very Loose 0-4 0- 11 0-4 Loose 4 - 10 11 -26 4- 10 Medium Dense 10- 30 26- 74 10 - 30 Dense 30- 50 74- 120 30-47 Very Dense More than 50 More than 120 More than 47 CONSISTENCY - FINE-GRAINED SOILS Consistency Standard Penetration Dames& Moore Sampler Dames& Moore Sampler Unconfined Compressive Resistance (140-pound hammer) (300-pound hammer) Strength (tsf) Very Soft Less than 2 Less than 3 Less than 2 Less than 0.25 Soft 2 -4 3 -6 2 - 5 0.25 -0.50 Medium Stiff 4 -8 6 - 12 5 - 9 0.50- 1.0 Stiff 8 - 15 12 - 25 9- 19 1.0- 2.0 Very Stiff 15 - 30 25 - 65 19- 31 2.0-4.0 _ Hard More than 30 More than 65 More than 31 More than 4.0 PRIMARY SOIL DIVISIONS GROUP SYMBOL GROUP NAME CLEAN GRAVELS GW or GP GRAVEL GRAVEL (< 5%fines) (more than 50%of GRAVEL WITH FINES GW-GM or GP-GM GRAVEL with silt coarse fraction (z 5%and s 12%fines) GW-GC or GP-GC GRAVEL with clay COARSE GRAINED retained on GRAVELS WITH FINES GM silty GRAVEL SOILS No. 4 sieve) (> 12%fines) GC clayey GRAVEL GC-GM silty,clayey GRAVEL (more than 50% CLEAN SANDS retained on SAND (<5%fines) SW or SP SAND No. 200 sieve) (50%or more of SANDS WITH FINES SW-SM or SP-SM SAND with silt (50 co a o morion (Z 5%and s 12%fines) SW-SC or SP-SC SAND with clay passing SM silty SAND SANDS WITH FINES No. 4 sieve) SC clayey SAND (> 12%fines) SC-SM silty,clayey SAND ML SILT FINE-GRAINED CL CLAY SOILS Liquid limit less than 50 CL-ML silty CLAY (50%or more SILT AND CLAY OL ORGANIC SILT or ORGANIC CLAY passing MH SILT No. 200 sieve) Liquid limit 50 or CH CLAY greater OH ORGANIC SILT or ORGANIC CLAY HIGHLY ORGANIC SOILS PT PEAT MOISTURE ADDITIONAL CONSTITUENTS CLASSIFICATION Secondary granular components or other materials Term Field Test such as organics,man-made debris,etc. Silt and Clay In: Sand and Gravel In: very low moisture, Percent Fine-Grained Coarse- Percent Fine-Grained Coarse- dry dry to touch Soils Grained Soils Soils Grained Soils moist damp,without < 5 trace trace < 5 trace trace visible moisture 5 - 12 minor with 5 - 15 minor minor wet visible free water, > 12 some silty/clayey 15 - 30 with with usually saturated > 30 sandy/gravelly Indicate% GEODESIGN? SOIL CLASSIFICATION SYSTEM TABLE A-2 1 5575 SW Sequoia Parkway-Suite 100 Portland OR 97224 Off 503.968.8787 Fax 503.968.3068 o = u w •BLOW COUNT INSTALLATION AND DEPTH u Q Z nJ. •MOISTURE CONTENT% COMMENTS = MATERIAL DESCRIPTION >w 2 FEET W o H < (1111 RQD% V/I CORE REC% o so 100 ~o'o - ASPHALT CONCRETE(4 inches). / 0.3 • "° \AGGREGATE BASE(6 inches). f 0.8 Medium stiff to stiff, brown SILT(ML), trace sand; moist, sand is fine. 2.5— 11 2 • • s.o— becomes medium stiff, trace to minor sand at 5.0 feet 1 7.5 _ becomes soft to medium stiff; moist to wet at 7.5 feet 4 • 10.0— P becomes medium stiff at 11.0 feet 1 i • 12.5— with sand; wet at 12.0 feet 15.0— becomes stiff, sandy at 1 5.0 feet z trace sand; moist at 15.7 feet 17.5— zo.o— becomes sandy; wet at 20.0 feet 11 minor sand; moist at 20.7 feet A Exploration completed at a depth of 21 5 Surface elevation was not 21.5 feet. measured at the time of 22.5 _ exploration. H t- z 25.0 t- 0 V Z _ w - 00 27.5— W u _ a v m 30.0 - 0 SO 100 z L) DRILLED BY:Western States Soil Conservation.Inc. LOGGED BY:NAK COMPLETED:04/24/13 T u tW7 BORING METHOD:mud rotary(see report text) BORING BIT DIAMETER:4 7/8-inch GEODESIGN? REGENCYCEN-15-01 BORING B-1 z . 15575 SW Sequoia Parkway-Suite 100 PROPOSED GROCERY STORE IMPROVEMENTS FIGURE A-1 Portland OR 97224 MAY 2013 Off 503.968.8787 Fax 503.968.3068 TIGARD,OR Z o �= u w BLOW COUNT INSTALLATION AND DEPTH U Q Z - •MOISTURE CONTENT% COMMENTS MATERIAL DESCRIPTION w J ~til FEET a Q 110 RQD% l// CORE REC% W ~ to 50 100 —0.0 ,o ASPHALT CONCRETE (2.5 inches). 0.3 \AGGREGATE BASE(4 inches). f 0.6 Stiff, brown SILT with sand (ML); moist, sand is fine. 2.5— I 12 S.o— interbeds of sandy silt at 5.0 feet P200 11 2 9 • P200 a70w 7.5— interbeds of loose, silty sand at 8.0 feet IP 2 lo.o— becomes medium stiff, with sand to sandy; wet at 10.0 feet I ■ • 12.5— - v 15.0— ° interbeds of loose, silty sand at 16.0 7 feet 16.5 Surface elevation was not measured at the time of 17.5— Exploration completed at a depth of exploration. 16.5 feet. 20.0— 0 '" • 22.5 W I- z a• 25.0— -- I- 0 u z O 27.5— 8 stis V U m Z; 30.0 50 100 z DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:NAK COMPLETED:04/24/13 >- V `•' u BORING METHOD:hollow stem auger(see report text) BORING BIT DIAMETER:4 1/4-inch GEODESIGN? REGENCYCEN-15-01 BORING B-2 ire z . • 15575 SW Sequoia Parkway-Suite 100 PROPOSED GROCERY STORE IMPROVEMENTS PortlandOR97224 MAY 2013 FIGURE A-2 Off 503.968.8787 Fax 503.968.3068 TIGARD,OR Z o �= u w ♦BLOW COUNT INSTALLATION AND DEPTH u Q Z a •MOISTURE CONTENT% COMMENTS = MATERIAL DESCRIPTION >w 1– g FEET a w <Lel !i i i RQD• I CORE REC% —o.o 0 50 100 — ,0 \ASPHALT CONCRETE(3 inches). _ r 0.3 f-7 \AGGREGATE BASE(8 inches). 0.9 – Medium stiff to stiff, brown SILT with Geotextlle fabric at 0.9 foot. - sand to sandy SILT(ML); moist. 2.5— s.o— becomes stiff, sandy at 5.0 feet y • 5- Loose, brown, silty SAND (SM)to 7.0 • medium stiff, sandy SILT(ML); moist, 6 _ sand is fine. A 10.0— Medium stiff, brown SILT with sand 9.5 _ (ML); wet. • becomes sandy at 1 1.0 feet • 12.5— 15.0— becomes stiff at 1 5.0 feet l � =4 with orange mottles at 16.0 feet - Exploration completed at a depth of 16.5 Surface elevation was not p p p measured at the time of 17.5— 16.5 feet. _ exploration. 20.0 I- Y a f ▪ 22.5 a I- z °• 25.0— I- 0 z • 27.5 W u E. TI ▪ 30.0 0 50 100 DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:NAK COMPLETED:04/24/13 u z BORING METHOD:hollow-stem auger(see report text) BORING BIT DIAMETER:41/4-inch ce o G EODESIGN? REGENCYCEN-15-01 BORING B-3 U z E 15575 SW Sequoia Parkway-Suite 100 PROPOSED GROCERY STORE IMPROVEMENTS FIGURE A 3 Fs) Portland MAY 2013 Off 503.968.8787 Fax 503.968.3068 TIGARD,OR Z u �= u w •BLOW COUNT INSTALLATION AND' DEPTH u Q Z •MOISTURE CONTENT% COMMENTS = MATERIAL DESCRIPTION >w g FEET w w Q RQD96 V/,I CORE REC% v, 50 100 ASPHALT CONCRETE (2.5 inches). f 0.3 °- �- \AGGREGATE BASE(6 inches). ft 0.8 - Stiff, brown SILT(ML), minor sand; - moist. 2.5— _ 11 2 • s.o— medium stiff to stiff at 5.0 feet _ 11 = 7.5— medium stiff, with sand; moist to wet at • 11 7.5 feet A • 10.0 4 a I 6 12.5— 15.0 becomes wet at 1 5.0 feet I, 2 17.5— — 20.0— becomes stiff at 20.0 feet o - minor sand; moist at 20.7 feet A� • Exploration completed at a depth of 21.5 Surface elevation was not measured at the time of 22.5 21.5 feet. exploration. 1- z • 25.0- E 0 u z O 27.5 u u • 30.0 0 SO 100 z DRILLED BY:Western States Soil Conservation.Inc. LOGGED BY:NAK COMPLETED:04/24/13 >- V BORING METHOD:hollow-stem auger(see report text) BORING BIT DIAMETER:4 1/4-inch u GEODESIGN? REGENCYCEN-15-01 BORING B-4 z Q 15575 SW Sequoia Parkway-Suite 100 PROPOSED GROCERY STORE IMPROVEMENTS Off OR MAY 2013 TIGARD,OR FIGURE A-4 ACRONYMS ACRONYMS AC asphalt concrete ASTM American Society for Testing and Materials BGS below ground surface CRB Columbia River Basalt g acceleration due to gravity H:V horizontal to vertical IBC International Building Code MSL mean sea level OSHA Occupational Safety and Health Administration pcf pounds per cubic foot pci pounds per cubic inch PGA peak ground acceleration psf pounds per square foot SOSSC State of Oregon Structural Specialty Code SPT standard penetration test L'NDESIG N r, RegencyCen-1 5-01:050613 www.geodesigninc.com