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Report g EIVED MACTEC engineering and constructing a better tomorrow CITY _ 3 1 20) eutto GQ C 1ON March 21, 2006 • Mr. Chad Gorma 030 Halle Properties, LLC City of Tigard 20225 North Scottsdale Road d Plans Scottsdale, Arizona 85255 Ap • V `' Te By l..�� Date L �7 Subject: Letter of Transmittal and Certification ((Jj1/442_ A Proposed Discount Tire Co. Inc. Store SE of Highway 99 West & Southwest 68 Parkway Tigard, Oregon MACTEC Project No. 4975 -06- 9002.02 Dear Mr. Gorman: MACTEC Engineering and Consulting, Inc. (MACTEC) representatives have completed the Geotechnical Engineering Report for the proposed Discount Tire Co. Inc. Store to be located in Tigard, Oregon. This work was performed in general accordance with our Master Services Agreement between MACTEC and Halle Properties, LLC, dated August 31, 2000 and numbered 70200 -0 -0295. The Geotechnical Evaluation report prepared for the above site as requested by MACTEC and Halle Properties, LLC is attached. This report has been prepared for the development of the project dcscribed and is for the sole use of • The Reinalt- Thomas Corporation, a Michigan Corporation, Halle Properties, LLC, an Arizona limited liability company, and their subsidiaries, affiliates and successors. We at MACTEC are committed to providing quality engineering services combined with client satisfaction in order to achieve a continuing relationship with our clients. We appreciate the opportunity to provide these services for you. If you have any questions regarding any of the other engineering and testing services MACTEC provides, please do not hesitate to contact us. Sincerely, MACTEC ENGINE RUN ' t+ CONSULTING, INC. • • ark Harti , P... ,J i Winney, P.E. Project Engineer / rincipal Engineer . MH:JW:cm Attachments OFFICE COPY (pro.jects\ 4975 \4975 -06- 9002 \deliverables \02 \letter of transmittal and certification) MACTEC Engineering and Consulting, Inc. 3630 East Wier Avenue • Phoenix, AZ 85040 • Phone: 602.437.0250 • Fax: 602.437.3675 www.mactec.com 4 MACTEC engineering and constructing a better tomorrow DISCUSSION OF GEOT.FCHNICAL ISSUES Proposed Discount Tire Co. Inc. Store SE of Highway 99, W & SW 68 Parkway • Tigard, Oregon MACTEC Project No. 4975 -06- 9002.02 March 20, 2006 The purpose of this information is to provide a brief discussion of the key geotechnical issues associated with the development of this site as proposed by Halle Properties, LLC. The issues discussed here shall not be construed as all inclusive, and each reader shall make his or her own assessment of the important issues related to this site by reading in its entirety the Geotechnical Engineering Report prepared for this project dated March 15, 2006, The Riley Group, Inc. Project No. 2006 -048. MACTEC assumes no responsibility for the decisions or inferences made by any person who relies on the information here without reading the referenced Geotechnical Engineering Report. Existing Soil Conditions The field investigation indicated that the upper 3 to 5 feet of the subgrade consists of soft to stiff, clay and silt soils underlain by basalt rock layers. The native clayey site soils are not suitable as structural fill. Groundwater seepage from a perched water table was encountered in some test pits during field explorations at depths of 2.5 to 8.5 feet below ground surface elevations. Footing Foundations and Slab -On -Grade The proposed building foundations may be supported on conventional spread and perimeter footings founded on suitable native soils or structural fill. If soft soils are encountered at footing bottom level, they should be removed to a depth of 24 inches and replaced with structural fill. The upper 12 inches of native soil below slabs on grade shall be removed and replaced with structural fill. After general grading operations are completed and before placement of structural fill, soft areas shall be determined through proofrolling operations. Pavement Areas Pavement subgrade should consist of 12 inches of structural fill over native soils. Recommended pavement sections consist of 4 inches of asphalt concrete over 8 inches of crushed rock base for heavy truck traffic areas, and 3 inches of asphalt concrete over 6 inches of crushed rock base in general parking areas. Recommended PCCP sections include 6 inches of concrete pavement over 4 inches of crushed rock base supported by 12 inches of structural fill. MACTEC ENGINEE ING A D CONSULTING, INC. /i I; if . Mark 1 -Iart' r, P.I. ;' Jol Winney, P.E. Project Engineer ,.principal Engineer MH:JW:cm (projcct\4975\ 4975 -06- 9002 \dcliverublcs \02\gcotech summary) MACTEC Engineering and Consulting, Inc. 3630 East Wier Avenue • Phoenix, AZ 85040 • Phone: 602.437.0250 • Fox: 602.437.3675 www.mactec.com ri The Riley Group Inc. GEOTECHNICAL ENGINEERING REPORT Proposed Discount Tire SE of Highway 99 W & SW 68 Parkway Tigard, OR 97223 Project No. 2006 -048 Prepared By: The Riley Group, Inc. 17522 Bothell Way NE Bothell, WA 98011 Prepared for: Mr. Mark Hartig MACTEC Engineering and Consulting, Inc. 3630 East Wier Avenue Phoenix, AZ 85040 March 15, 2006 Serving the Pacific Northwest Main Office: 17.522 Bothell Way NE, Bothell, WA 98011 Tel (425) 415 -0551 • Fax (425) 415 -0311 The Riley Group Inc. March 15, 2006 Mr. Mark Hartig MACTEC Engineering and Consulting, Inc. 3630 East Wire Avenue Phoenix, AZ 85040 Subject: Geotechnical Engineering Report Proposed Discount Tire SE of Highway 99W & SW 68 Parkway Tigard, OR 97223 Project No. 2006 -048 Dear Mr. Hartig: As requested, The Riley Group, Inc. (Riley) has performed a geotechnical engineering study for the above - referenced subject site. The attached report presents our findings and recommendations for the geotechnical aspects for the project design and construction. Our field exploration indicates that the site is generally underlain by 3 to 5 feet soft to stiff clayey SILT overlying stiff silty CLAY. Test pits TP -3 and TP -7 encountered basalt rock layers at depth of 3 and 11.5 feet below ground surface (bgs). Groundwater seepage was encountered during our field explorations at depths of 2.5 to 8.5 feet bgs. Based on the subsurface soil condition, the upper soft soil is not suitable for directly supporting the proposed building foundations. Riley recommends that the proposed Discount Tire store be supported on conventional spread footing foundations bearing on 24 inches of structural fill. The floor slab and pavement should be supported on 12 inches of structural fill. Since the native soil is moisture sensitive, Riley recommends that all site grading and earthwork activities he performed in dry weather conditions. The owner /contractor should be prepared to deal with soft ground problems if the earthwork occurs during periods of precipitation, particularly if construction occurs during the wet winter season. Serving the Pacific Northwest Main Office: 17522 Bothell Way NE, Bothell, WA 98011 Tel (425) 415 -0551 • Fax (425) 415 -0311 This report provides our geotechnical findings and recommendations for the project. These recommendations should be incorporated into the project design and construction. We trust the information presented is sufficient for your current needs. If you have any questions or require additional information, please call. <� �EO PROF Sincerely yours, so NGJNF 9 S� THE RILEY GROUP, INC. � , 19328P. `* OREGON 6/ 15 19 �.(, 11. AUNO\ I aPIRES: Jur�e 30, 7.4.0, `?/ r /o, vic e_. Chien -Lin (Johnny) Chen, P.E. Ricky R. Wang, Ph.D., P.E. Project Engineer Principal Engineer JC /RW • The Riley Group, Inc. TABLE OF CONTENTS 1.0 PROJECT DESCRIPTION I 2.0 SCOPE OF WORK I 3.0 SITE CONDITIONS 2 3.1 SURFACE 2 • 3.2 SOILS 2 3.3 GROUNDWATER 2 3.4 SEISMIC CONSIDERATIONS 2 4.0 DISCUSSION AND RECOMMENDATIONS 3 4.1 GENERAL 3 4.2 SITE PREPARATION AND GRADING 3 4.3 EXCAVATIONS AND FILL SLOPES 4 4.4 FOUNDATIONS 5 4.5 RETAINING WALLS 5 4.6 SLAB -ON -GRADE CONSTRUCTION 6 4.7 DRAINAGE 6 4.8 UTILITIES 6 4.9 PAVEMENTS 7 5.0 ADDITIONAL SERVICES 8 6.0 LIMITATIONS s LIST OF FIGURES Figure • 1 Site Vicinity Map Figure 2 Geotechnical Exploration Plan Figure 3 General Slope Fill Detail Figure 4 Keystone Wall Section Figure 5 Typical Footing Drain Detail LIST OF APPENDICES Appendix A Field Exploration and Laboratory Testing ■ The Riley Group, Inc. Geotechnical Engineering Report / March 15, 2006 Discount Tire, Tigard, OR Project #2006 -048 1.0 PROJECT. DESCRIPTION The subject site is located at the southeast portion of Highway 99W (SW Pacific Highway) and SW 68 Parkway in Tigard, Oregon. The approximate location of the site is shown on the Site Vicinity Map, Figure 1. The subject site is currently a vacant lot and covered by grass. The proposed project consists of constructing a 5,487 square feet Discount Tire store building with parking and associated utilities. Our understanding of the project is based on the preliminary site plan prepared by Discount Tire Company, Inc. dated February 23, 2006. At the time of the preparation of this report, detailed grading and building plans were not available to us for review. Based on our experience of similar development, we expect that the proposed Discount Tire facility will consist of a one -story masonry building using perimeter walls and isolated columns. The maximum perimeter wall load will be 1 to 2 kips per linear foot and the maximum column load is up to 75 kips. The floor slab will be supported on slab -on- grade. Based on the site condition, Riley expects that site grading will need fill up to 10 feet in the south portion of the site. The recommendations in the following sections of this report are based upon our understanding of the above design features. If actual features vary or changes are made, we should review them in order to modify our recommendations as required. In addition, Riley would like to review final design drawings and specifications to verify that our project understanding is correct and that our recommendations have been properly interpreted and incorporated into project design and construction. 2.0 SCOPE OF WORK On March 3, 2006, Riley excavated a total of eight test pits to a maximum depth of 12 feet bgs. Test pits were excavated using a track - mounted excavator. Test pits TP -2, TP -3, TP -6, and TP -7 were excavated within the proposed building footprint area, and test pits TP -1, TP -4, TP -5 and TP -8 were excavated in the proposed driveway and parking areas. The approximate test pit locations are shown on Figure 2. Using the information obtained from our subsurface exploration, we performed analyses to develop geotechnical recommendations for project design and construction of the following: D Soil and groundwater conditions D Retaining walls D Seismic considerations D Slab -on -grade D Site preparation and grading D Drainage • Excavations and slopes D Utilities D Foundations D Pavements The Riley Group, Inc. Geotechnica! Engineering Report 2 March 15, 2006 Discount Tire, Tigard, OR Project #2006 -048 3.0 SITE CONDITIONS 3.1 Surface The site is a triangle- shaped parcel of land approximately 43,686 square feet in size. The site is bounded to the northwest by Highway 99 W, to the east by an asphalt driveway, and to the south by Howard Johnson Motel and parking lot. The subject site is currently a vacant lot and covered by grass: The site slopes down to the southwest with an overall elevation difference of approximately 20 feet. A rockery up to 5 feet tall was observed along the south property line. 3.2 Soils The site is generally underlain by 3 to 5 feet soft to stiff clayey SILT overlying stiff silty CLAY. Test pits TP -3 and TP -7 encountered basalt rock layers at depth of 3 and 11.5 feet bgs. Review of the Geologic Map of Oregon, by George W. Walker and Norman S. MacLeod (1991) indicates that the site geology is mapped as (Map Unit Qs) lacustrine and fluvial deposits. The native soil is described as unconsolidated lacustrine clay, silt, sand, and gravel. These descriptions are similar to the findings in our field exploration. More detailed descriptions of the subsurface conditions encountered are presented on the Test Pit Logs, Figures A -2 through A -5 in Appendix A. Atterberg limits were also performed on selected soil samples. 3.3 Groundwater Perched groundwater seepage was encountered at depths from 2.5 to 8.5 feet bgs in the northeast (higher) portion of the site during our subsurface investigation, which reached a maximum depth of 12 feet bgs. Fluctuations in groundwater level should be expected on a seasonal and annual basis. The level will be highest during the extended periods of heavy seepage in the wet winter months. Given the time that the field exploration was performed, Riley believes that the groundwater should be close to the season -high level. 3.4 Seismic Considerations Based on 2003 International Building Code (IBC), the site soil is Class E from Table 1615.1.1. The earthquake spectral response acceleration at short periods (S is 105 %g and at I - second period (Si) is 37% g. Review of the Portland Metropolitan Relative Earthquake Hazard Maps by M A. Mabey and others (1997) indicates that the project site is located in "Zone B" which is considered an intermediate to high hazard area. The Riley Group, Inc. Geotechnical Engineering Report 3 March 15, 2006 Discount Tire, Tigard, OR Project #2006 -048 Liquefaction Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in water pressure induced by vibrations from a seismic event. Liquefaction mainly affects geologically recent deposits of fine- grained sands that are below the groundwater table. Soils of this nature derive their strength from intergranular friction. The generated water pressure or pore pressure essentially separates the soil grains and eliminates this intergranular friction, thus reducing or eliminating the soil's strength. We reviewed the results of the field and laboratory testing and assessed the potential for liquefaction of the site's soil during an earthquake. Since the native soil below the groundwater is silty clay, Riley considers that the possibility of liquefaction during an earthquake is low. 4.0 DISCUSSION AND RECOMMENDATIONS 4.1 General Based on our study, the site is suitable for the proposed construction from a geotechnical standpoint. However, the soft soil at shallow depth is not suitable for directly supporting the foundation and floor slab. If the soft soil is encountered below the proposed perimeter wall and column footings, it should be overexcavated approximately 24 inches and replaced with structural fill. Slab -on -grade and pavement should be supported on 12 inches of structural fill over native soil subgrade. Detailed recommendations regarding the above issues and other geotechnical design considerations are provided in the following sections. These recommendations should be incorporated into the final design drawings and construction specifications. 4.2 Site Preparation and Grading To prepare the site for construction, surface stripping depths of up to six inches should be expected to remove the topsoil. Once stripping, clearing and other preparing operations are complete, cuts and fills can be made to establish desired building grades. Prior to placing fill, we recommend proofrolling all exposed surface to determine if any isolated soft and yielding areas are present. Proofrolling should also be performed in cut areas that will provide direct support for new construction. The native soil has a high percentage of fines and is characteristically moisture sensitive. Riley recommends that all site grading and earthwork activities be performed in dry weather conditions. The owner /contractor should be prepared to deal with soft ground problems if the earthwork occurs during periods of precipitation, particularly if construction occurs during the wet winter season. Based on our experience in the Pacific Northwest, a combination of 18 inches of crushed rock over a geotextile fabric such as Mirafi 500X on native soil subgrade should be The Riley Group, Inc. Geotechnical Engineering Report 4 March 15, 2006 Discount Tire, Tigard, OR Project #2006 -048 • sufficient to establish a stable grade for construction equipment if the construction occurs during periods of precipitation or in the wet season. The native soil has a high percentage of fines and will not be suitable for being used as structural fill. We recommend importing a material that meets the grading requirements listed in the Table 1. Table 1.Structural Fill U.S. Sieve Size Percent Passing • 3 inches 100 percent No. 4 sieve 0 to 75 percent No. 200 sieve 0 to 5 percent * *Based on minus 3/4 inch fraction. Structural fill materials should be placed in uniform loose layers not exceeding 12 inches and compacted to a minimum of 95 percent of the soil's maximum density, as determined by ASTM Test Designation D -1557 (Modified Proctor) until the desired finished grade is met. The moisture content of the soil at the time of compaction should be within about two percent of its optimum, as determined by this ASTM method. 4.3 Excavations and Fill Slopes Excavations at the site with confined spaces, such as basements, footings, utility trenches, etc., must be completed in accordance with local, state, or federal requirements. Based on Occupational Safety and Health Administration (OSHA) regulations, the undisturbed native soil classifies as a Group B soil. Accordingly, for excavations more than four feet but less than 20 feet in depth, the temporary side slopes should be laid back with a minimum slope inclination of 1:1 (Horizontal: Vertical) in the undisturbed native soil. If there is insufficient room to complete the excavations in this manner, or excavations greater than 20 feet in depth are planned, using temporary shoring to support the excavations should be considered. The permanent cut and fill slopes should be graded with a finished inclination no greater than 2:1 (Horizontal:Vertical). Upon completion of construction, the slope face should be trackwalked, compacted and vegetated, or provided with other physical means to guard against erosion. Final grades at the top of the existing slope must promote surface drainage away from the existing slope crest. Water must not be allowed to flow in an uncontrolled fashion over the slope face. If it is necessary to direct surface runoff towards the slope, it should be controlled at the top of the slope, piped in a closed conduit installed on the slope face, and taken to an appropriate point of discharge - beyond the toe. The Riley Group, Inc. • Geotechnical Engineering Report 5 March 15, 2006 Discount Tire, Tigard, OR Project #2006 -048 ~ ! All fill placed for slope construction should meet the structural fill requirements as described in the Site Preparation and Grading section of this report. In addition, if new fills are placed over existing slopes of 20 percent or greater, the structural fill should be keyed and benched into competent native slope soils. A typical slope key and bench configuration is shown on the general slope fill detail on Figure 3. 4.4 Foundations Spread Footing Following the preparation and grading, Riley recommends that the proposed building foundations can be supported on conventional spread footings bearing on 24 inches of structural fill after overexcavation. Perimeter foundations exposed to the weather should be at a minimum depth of 18 inches below final exterior grades. Interior foundations can be constructed at any convenient depth below the floor slab. We recommend designing foundations for a net allowable bearing capacity of 2,000 pounds per square foot (psf). For short-term loads, such as wind and seismic, a /3 increase in this allowable capacity can be used. For designing foundations to resist lateral loads, a base friction coefficient of 0.35 can be used. passive earth pressures acting on the side of the footing and buried portion of the foundation stem wall can also be considered for resisting lateral loads. We recommend calculating this lateral resistance using an equivalent fluid weight of 250 pcf. At perimeter locations, we recommend not including the upper 12 inches of soil in this computation because they can be affected by weather or disturbed by future grading activity. This value assumes the foundation will be constructed neat against competent fill soil or backfilled with structural fill as described in the Site Preparation and Grading section. The recommended passive resistance value includes a safety factor of 1.5. With spread footing foundations as recommended, you should expect maximum total and differential post - construction settlements of 1 inch and '/z inch, respectively. 4.5 Retaining Walls Keystone Block Wall Base on the preliminary site plan, a segment block wall up to 10 feet may be constructed alone the east and south site boundaries. Riley recommends that Keystone retaining wall be used. A Keystone retaining wall, which is a proprietary retaining wall system, can he used to resist lateral earth pressures either as a gravity wall or combined with Geogrid reinforced fill. The system includes manufactured segmental block units designed to be connected to each other by fiberglass pins. We recommend installing Geogrid reinforcement in the structural fill behind the Geogrid. The The Geogrid length should not be less than the height of the retaining wall face. The maximum wall height should be limited to 16 feet. We . also recommend using granular structural fills compacted to 95 The Riley Group, Inc. Geotechnical Engineering Report 6 March 15, 2006 Discount Tire, Tigard, OR Project #2006 -048 percent of the soil's maximum dry density according to ASTM D - l55. General design details for this construction are shown on Figure 4. 4.6 Slab - on - Grade Construction With site preparation completed as described in the Site Preparation and Grading section, suitable support for slab -on -grade construction should be provided. Riley recommends that slab -on -grade construction be supported on 12 inches of structural fill. Immediately below the floor slab, we recommend placing a four -inch thick capillary break layer of clean, free- draining gravel that has less than five percent passing the No. 200 sieve. This material will reduce the potential for upward capillary movement of water through the underlying soil and subsequent wetting of the floor slab. Typically, an eight to ten -mil thick plastic membrane is placed on a four -inch thick layer of clean gravel to avoid moisture by vapor transmission. The membrane should be covered with 1 to 2 inches of clean, moist sand to guard against damage during construction and to aid in curing of the concrete. For the anticipated floor slab loading, we estimate post - construction floor settlements of '4 to '/z inch. For thickness design of the slab subjected to point loading from storage racks and fork Iift vehicle traffic, we recommend using a subgrade modulus (Ks) of 150 pounds per square inch per inch of deflection (pci). 4.7 Drainage Surface Final exterior grades should promote free and positive drainage away from the building area. Water must not be allowed to pond or collect adjacent to foundations or within the immediate building area: For non - pavement locations, we recommend providing a minimum drainage gradient of three percent for a minimum distance of ten feet from the building perimeter. In paved locations, a minimum gradient of one percent should be provided unless provisions are included for collection and disposal of surface water adjacent to the structure. Subsurface We recommend installing perimeter foundation drains. A typical recommended drain detail is shown on Figure 5. The foundation drains and roof downspouts should be tightlined separately to an approved discharge facility. Subsurface drains must be laid with a gradient sufficient to promote positive flow to a controlled point of approved discharge. 4.8 Utilities Utility pipes should be bedded and hackfilled in accordance with American Public Works Association (APWA) specifications. For site utilities located within the City of Tigard right -of -ways, bedding and backfill should be completed in accordance with City of Tigard The Riley Group, Inc. Geotechnical Engineering Report 7 March 15, 2006 Discount Tire, Tigard, OR Project #2006 -048 specifications. The trench backfill should be placed and compacted as structural fill, as described in the Site Preparation and Grading section. Where utilities occur below unimproved areas, the degree of compaction can be reduced to a minimum of 90 percent of the soil's maximum density as determined by the referenced ASTM standard. As noted, excavated soils are not suitable to be used as backfill. The backfill material should satisfy the structural fill requirements listed in the Site Preparation and Grading section. Basalt rock may be encountered during trench excavation. The earth subcontractor should be prepared to break up the basalt if encountered. 4.9 Pavements At the time of preparing this report, Riley is not aware of that Discount Tire has any special requirements for pavement. The recommendation is based on local experience and soil condition. Pavement subgrades should be prepared as described in the Site Preparation and Grading section of this report and as discussed below. The subgrade should consist of 12 inches of structural fill over native soil. Typically, a geotextile fabric such as Amoco 2002 or equivalent can be placed on the subgrade. Regardless of the relative compaction achieved, the subgrade must he firm and relatively unyielding before paving. The subgrade should be proofrolled with heavy construction equipment to verify this condition before paving. With the pavement subgrade prepared as described above, we recommend that the general parking area be paved with flexible pavement. The following pavement sections are recommended: Y For heavy truck traffic areas: 4 inches of asphalt concrete (AC) over 8 inches of crushed rock base (CRB) over 12 inches of structural fill; and > For general parking areas: 3 inches of AC over 6 inches of CRB over 12 inches of structural fill. The paving materials used should conform to the Oregon Department of Transportation (ODOT) specifications for Class B asphalt concrete and CRB surfacing. Long -term pavement performance will depend on surface drainage. A poorly- drained pavement section will be subject to premature failure as a result of surface water infiltrating into the subgrade soils and reducing their supporting capability. For optimum pavement performance, surface drainage gradients of no less than two percent are recommended. Also, some degree of longitudinal and transverse cracking of the pavement surface should be expected over time. Regular maintenance should be planned to seal cracks when they occur. The Riley Group, Inc. Geotechnical Engineering Report 8 March 15, 2006 Discount Tire, Tigard, OR Project #2006 -048 5.0 ADDITIONAL SERVICES Riley is available to provide further geotechnical consultation as the project design develops. We should review the final design and specifications in order to verify that earthwork and foundation recommendations have been properly interpreted and incorporated into project design and construction. Riley is also available to provide geotechnical engineering and monitoring services during construction. The integrity of the earthwork and construction depends on proper site preparation and procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this scope of work. If these services are desired, please let us know and we will prepare a cost proposal. 6.0 LIMITATIONS This report is the property of The Riley Group, Inc. and was prepared in accordance with generally accepted geotechnical engineering practices. This report is intended for specific application to the Proposed Discount Tire at the southeast of Highway 99W and SW 86` Parkway in Tigard, Oregon and for the exclusive use of MACTEC Engineering and Consulting, Inc. and their authorized representatives. No other warranty, expressed or implied, is made. The analyses and recommendations presented in this report are based upon data obtained from the test pits excavated on -site. Variations in soil conditions can occur, the nature and extent of which may not become evident until. construction. 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Proposed Discount Tire 4r 17522 BOTHELL WAY NE BOTHELL, WASHINGTON 98011 Site Vicinity Map Figure 1 Site Address: SE of Highway 99 W & SW 68th Parkway, Tigrad, Oregon 'F � 1 i r • , V iif 411 r i II � �? � O i „. - (1..i r., .. . -1?-4. in • • ; 1 . /Ili Ili 1 . 6 • i 'll' ''' ,:wr.�i�' r� sR" i�i�i.■ e�I■ iw Iw■ �> e.. ��� !�i�t�IrAv�.�!!��+,.w!,!�_r ..,0 ...,,,,1 j A o 6ITE AREA, 43,68326 6F. (L003 AC.) Pi? • 'r'U (J aIILDNG AREA/ S.4a1 8P. SH ,PL1.1 PARKING cam 32 PARKING SPACES - NCLUDIM 2 ACCESSIBLE SPACES Reference: • ' �' • _... _ . ...:.... N Figure modified from preliminary site plan prepared by Discount Tire Co. Inc. dated February 23, 2006. ` ALS Geotechnical test pit location excavated by The Riley TP -1 Group, Inc. on March 3, 2006. DRAWING NOT TO SCALE T he R i ley. Group, Inc. • Proposed Discount Tire Ar 17522 BOT HELL WAY NE Geotechnical Exploration Plan Figure 2 BOTHELL, WASHINGTON 98011 Site Address: SE of Highway 99 W & SW 68th Parkway, Tigard, Oregon SLOPE TO DRAIN NEW STRUCTURAL FILL ````•"` MAXIMUM SLOPE GRADIENT: 2:1(H:V) '► *e%. ����►�' ‘, 1 ' • - EXISTING , .l� - .. -. GRADE ,- 1 ∎� - - . ... _� ' , , , j �� TYPICA BE - MAY REQ UIR E SUBDRAIN IF SEEPAGE - ! � � �`�� , -.... , � : ; . CONDITIONS ARE INDICATED GRADE AFTER THE REMOVAL OF - - - TOPSOIL AND OTHER LOOSE SOILS KEY CUT AND TOE DRAIN - 4" DIAMETER PERFORATED PIPE ENVELOPED IN 1 cu.ft. 3/4" DRAINAGE GRAVEL NOT TO SCALE NOTES 1. SLOPE SHOULD BE STRIPPED OF TOPSOIL AND UNSUITABLE SOILS PRIOR TO PLACING ANY FILL. 2. "BENCHES" SHOULD BE A MINIMUM OF 6 FEET WIDE. 3. "KEY" SHOULD BE MINIMUM 2 FEET DEEP AND 6 FEET WIDE, EXTENDING THE FULL LENGTH OF THE SLOPE FACE. 4. FINAL SLOPE FACE SHOULD BE DENSIFIED BY COMPACTION. 5. PLANT OR HYDROSEED SLOPE FACE TO REDUCE EROSION POTENTIAL. 6. ALL STRUCTURAL FILL SHOULD BE COMPACTED TO 95% OF SOILS MAXIMUM DRY DENSITY PER ASTM 0 -1557 (MODIFIED PROCTOR). rtif The Riley Group, Inc. Proposed Discount Tire 17522 BOTHELL WAY NE General Slope Fill Detail Figure 3 BOTHELL, WASHINGTON 98011 Site Address: SE of Highway 99 W & SW 68th Parkway, Tigard, Oregon • WALL BATTER 8 INCH HIGH SEGMENTED KEYSTONE BLOCK UNITS ( GEOGRID 1 12" 12 f .........., . - ';;':;' — — LAYER 3 o: -; I :. LAYER 2 : 4 : STRUCTURAL FILL - •'0;t: (SEE REPORT TEXT FOR REQUIREMENTS) RIV •' -- -- - LAYER 1 �' L 1 1 12 ME " _ 3/4 MINUS WASHED DRAIN ROCK 6 _ f :k : :1 r 121 COMPACTED 5 / 8 MINUS CRUSHED ROCK BASE FOUNDATION L -JL . --I 4" PERFORATED PVC PIPE TAKEN TO APPROVED POINT OF DISCHARGE \OT TO SCALE NOTES: . 1. ALL GEOGRID LAYER HEIGHTS ARE MEASURED FROM TOP OF CRUSHED ROCK BASE FOUNDATION. 2. KEYSTONE BLOCK CONSTRUCTION AND CONNECTION OF GEOGRID TO WALL TO BE COMPLETED PER MANUFACTURERS SPECIFICATIONS. 3. THE GEOGRID LENGTH L' SHOULD NOT BE LESS THAN WALL HEIGHT H'. ,a The Riley Group, Inc. Proposed Discount Tire 17522 BOTHELL WAY NE Keystone Wall Section Figure 4 BOTHELL, WASHINGTON 98011 Site Address: SE of Highway 99 W & SW 68th Parkway, Tigard, Oregon BUILDING SLAB ave v e . , ,e .s d v e / \ / /\ / /\ /./ . ' d - COMPACTED: . ° e• . . '.; ` ;:: /\ \ •;BACKFILL: • \ FILTER \A • ,.. / FABRIC \ ° e e ° , . a d d fi r. 6. _ ....iv() \\ / / /� / / /\ / / /� / / /\ / / /� // A ./\ / // 4" PERFORATED PIPE 3/4" WASHED ROCK OR PEA GRAVEL NOT TO SCALE Ar . ' The Riley Group, Inc. Proposed Discount Tire ELL , WASHINGTON WAY O N 98011 BOTHELL, Typical Footing Drain Detail Figure 5 BOT Site Address: SE of Highway 99 W & SW 68th Parkway, Tigard, Oregon • Geotechnical Engineering Report March 15, 2006. • Discount Tire, Tigard, OR Project #2006 -048 APPENDIX A FIELD EXPLORATION AND LABORATORY TESTING Proposed Discount Tire SE of Highway 99 W & SW 68 Parkway Tigard, OR 97223 On March 3, 2006, we performed our field exploration using a .track- mounted excavator. We explored subsurface soil conditions at the site by excavating eight test pits to a maximum depth of 12 feet below existing grade. The test pit locations are shown on Figure 2. The test pit locations were approximately determined by measurements from existing property lines and paved roads. The Test Pit Logs are presented on Figures A -2 through A- 5. A geologist/engineer from our office conducted the field exploration and classified the soil conditions encountered, maintained a log of each test , pit, obtained representative soil samples, and observed pertinent site features. All soil samples were visually classified in accordance with the Unified Soil Classification System (.USCS) described on Figure A -l. Representative soil samples obtained from the test pits were placed in closed containers and taken to our laboratory for further examination and testing. The moisture, content of typical sample was measured and is reported on the Test Pit Logs. The Riley Group, Inc. ! ., 1 LETTER MAJOR DIVISIONS SYMBOL TYPICAL DESCRIPTION i - i CLEAN Well- graded gravels, gravel -sand mixtures, little o GRAVELS GW or no fines. GRAVELS Poorly- graded gravels, gravel -sand mixtures, W rn M ore than 50% <5% fines GP little or no fines. z of coarse Silty gravels, gravel- sand -silt mixtures, m fraction is larger GRAVELS GM non - plastic fines. De J • a .? than No. 4 sieve with fines GC Clayey gravels, gravel- sand -clay mixtures, O _ plastic fines: W 0 E N SANDS CLEAN SW Well- graded sands, gravelly sands, little or no q CO fines. Ce , in z More than 50 SANDS Poorly- graded sands or gravelly sands, little or Q C of coarse <5% fines SP no fines. O `. Q fraction is SM Silty sands, sand -silt mixtures, non - plastic fines. 0 o smaller than No. SANDS h fines 2 4 sieve SC Clayey sands, sand -clay mixtures, plastic fines. a) ML Inorganic silts, rock flour, clayey silts with slight CD . c .� SILTS AND CLAYS plasticity a) N Inorganic clays of low to medium plasticity, (lean W Z E o ° Liquid limits CL clay). ,f, less than 50% < J z OL Organic silts and organic clays of low plasticity. 0 a N W SILTS AND CLAYS MH Inorganic silts, elastic. • m 13 Liquid limits greater CH Inorganic clays of high plasticity, (fat clays). M E than 50% E OH Organic clays of high plasticity. HIGHLY ORGANIC SOILS PT Peat. DEFINITION OF TERMS AND SYMBOLS Density O j Very loose SPT (Blows/Foot) 2" Outside diameter split spoon 0-4 I CD > Loose 4 -10 sampler Z Q Medium dense 10 -30 2.4" Inside diameter ring sampler or Q Dense 30 -50 Shelby tube ( / ) C 7 Very dense >50 Z Water level (date) Consistency SPT (Blows /Foot) Tr Torvane reading, tsf `. Very soft 0 -2 pp . Penetrometer reading, tsf O > - Soft 2 - DD Dry density, pcf I — Q Medium stiff 4 - 8 J J LL Liquid limit, percent CO 0 Stiff 8 - 15 pl Plasticity index Very stiff 15 - 30 N Standard penetration, blows per foot Hard >30 The Riley Group, Inc. Proposed Discount Tire 17522 a t ELL, WAS HINGTON 98011 WAY NE BOTHELL, WASHINGTON Unified Soil Classification System Figure A -1 BOT Site Address: SE of Highway 99 W & SW 68th Parkway, Tigard, Oregon Logged By: PL Date: 3/3/06 Test Pit No. Depth (ft) Soil Description Sample TP -1 Surface Grass. Depth (moisture) 0 - 1.5 Dark brown clayey SILT, trace roots, medium plasticity, moist, soft to medium stiff, (ML). 1.5 - 5 Brown clayey SILT, medium plasticity, 3.5 ft (31.5 %) moist, medium stiff to stiff, (ML). 5 - 7.5 Mottled grayish brown silty CLAY, medium 6 ft (29.3 %) plasticity, moist, medium stiff to stiff, (CL). 7.5 - 8 Reddish orange silty CLAY with dessicated 8 ft (29.9 %) basalt, very plastic, moist to wet, stiff, (CL). Terminated at 8 feet. Groundwater seepage encountered @ 8 ft. TP -2 Surface Grass. 0 - 2 Dark brown clayey SILT, trace roots, medium plasticity, moist, soft to medium stiff, (ML). 2 - 4 Brown clayey SILT, medium plasticity, moist, medium stiff to stiff, (ML). 4 - 7 Reddish orange silty CLAY with dessicated 4 ft (27.8 %) basalt, trace sand, very plastic, moist to 5 ft (27.9 %) wet, stiff, (CL). Atterberg Limits at 4 ft sample LL = 45.3 PI = 18.8 (CL) Terminated at 7 feet. Groundwater seepage encountered @ 6.5 ft. The Riley Group, Inc. Proposed Dtscount Tire 17522 BOTHELL WAY NE Test Pit Logs J Figure A -2 BOTHELL, WASHINGTON 98011 Address: SE of Highway 99 W & SW 68th Parkway, Tigard, OR I� - • Logged By: PL Date: 3/3/06 Test Pit No. Depth (ft) Soil Description Sample TP -3 Surface Grass. Depth (moisture) 0 - 2 Dark brown clayey SILT, trace roots, medium 2 ft (31.3 %) plasticity, moist, soft to medium stiff, (ML). 2 - 3 Brown clayey SILT, medium plasticity, 3 ft (28.5 %) moist, medium stiff to stiff, (ML). 3 - 6 Gray undulating basalt, damp, dense to very dense. 6 - 11.5 Reddish orange silty CLAY with dessicated 7 ft (48.0 %) basalt, trace sand, very plastic, moist, stiff 9 ft (59.1%) to very stiff, (CL). 11.5 - 12 Purplish gray dessicated basalt, damp to 12 ft (25.7 %) moist, dense. Atterberg Limits at 2 ft sample LL =44.7 PI =18.2 (ML) ■ IPP Terminated at 12 feet. Groundwater seepage encountered @ 7 ft. TP -4 Surface Grass. 0 - 3.5 Dark to light brown clayey SILT, scattered 2 ft (31.3 %) boulders, trace roots, medium plasticity, moist, soft to stiff, (ML). 3.5 - 8 Reddish yellow- orange silty CLAY with 6 ft (46.8 %) dessicated basalt, trace sand, very plastic, 8 ft (42.6 %) moist to wet, stiff to very stiff, (CL). Terminated at 8 feet. No groundwater seepage encountered. � The Riley Group, Inc. Proposed Discount Tire ' 17522 BOTHELLs WAY NE Test Pit Logs. I Figure A -3 I BOTHELL, WASHIN 98011 Address: SE of Highway 99 W & SW 68th Parkway, Tigard, OR r • Logged By: PL Date: 3/3/06 r Test Pit No. Depth (ft) Soil Description Sample TP -5 Surface Grass. Depth (moisture) 0 - 2 Dark brown clayey SILT, trace roots, medium plasticity, moist, soft to medium stiff, (ML). 2 - 4.5 Brown clayey SILT, medium plasticity, 2 ft (26.8 %) moist, medium stiff to stiff, (ML). 4.5 - 6.5 Reddish orange silty CLAY with dessicated 6.5 ft (39.9 %) basalt, trace sand, very plastic, moist, stiff • to very stiff, (CL). Terminated at 6.5 feet. No groundwater seepage encountered. TP -6 Surface Grass. 0 - 1.5 Dark brown clayey SILT, scattered boulders, trace roots, medium plasticity, moist, soft to stiff, (ML). 1.5 - 5 Brown clayey SILT, medium plasticity, 3 ft (32.0 %) moist, medium stiff to stiff, (ML). 5 - 11 Reddish yellow- orange silty CLAY with 9 ft (25.4 %) dessicated basalt, trace sand, very plastic, 11 ft (27.6 %) moist to wet, stiff to very stiff, (CL). Terminated at 11 feet. Groundwater seepage encountered @3 ft and 8.5 ft. �— The Riley Group, Inc. = Proposed Discount Tire 17522 BOTHELL WAY NE Test Pit Logs J Figure A -4 BOTHELL, WASHINGTON 98011 Address: SE of Highway 99 W & SW 68th Parkway, Tigard, OR I I `r i Logged By: PL Date: 3/3/06 Test Pit No. Depth (ft) Soil Description Sample TP -7 Surface Grass. Depth (moisture) 0 - 1 Dark brown clayey SILT, trace roots, medium plasticity, moist, soft to medium stiff, (ML). 1 - 4 Brown clayey SILT, medium plasticity, damp, 2.5 ft (22.3 %) moist, medium stiff to stiff, (ML). 4 - 11.5 Reddish orange silty CLAY with dessicated 7 ft (39.3 %) basalt, trace sand, very plastic, moist, stiff to very stiff, (CL). 11.5 - 12 Brownish black dessicated basalt with little clay, slightly plastic, moist, medium dense to dense. Terminated at 12 feet. Minor groundwater seepage encountered @ 3.5 ft, steady @ 5.8 ft. TP - 8 Surface Grass. _ 0 - 3.5 Dark to light brown clayey SILT, scattered boulders, trace roots, medium plasticity, moist, soft to stiff, (ML). 3.5 - 7 Reddish brown silty CLAY with dessicated 4.5 ft (32.8 %) basalt, trace sand, very plastic, moist, stiff to very stiff, (CL). Terminated at 7 feet. Groundwater seepage encountered © 2.5 ft. • The Riley Group, Inc. Proposed Discount Tire lir 17522 BOTHELL WAY NE Test Pit Logs Figure .4 -S BOTHELL, WASHINGTON 98011 Address: SE of Highway 99 W & SW 68th Parkway, Tigard, OR