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Report CIO/ 1L /'LtAl4 17: 7G on.77 Utuh'Hl,lr1V trVV 11V1. F'HUt bl /1t7 ��?[:nquteeifn9 ►nr Real-World Geotechnical Solutions Investigation 0 Design • Construction Support August 11, 2004 1T 200 -- o 0 3 Project No. 03 -8272 930 s v / N i * sr- Malcolm Eslingor Eslinger Builders, Inc. 11575 SW Pacific Hwy, PMB 160 Tigard, OR 97223 Fax 503 620 - 9475 Cc: John Meier/ Alex Hurley, Fax 503.925.8969 RE: KEYSTONE WALL DESIGN ATLANTA STREET OFFICE BUILDING TIGARD, OREGON Enclosed are our recommended design and construction details for the proposed segmental wall supporting the cut slope east of the proposed building. The segmental wall is a maximum of about 8 feet in retained height, and was modeled as a Keystone wall utilizing granular backfill and geogrid reinforcement. The wall will support native fine - grained soils. According to the piano provided, the wail backsiope profile is planned at a maximum of 2H :1V, and the frontslope is near level. Keystone standard or compac concrete masonry units may be used to construct the wall. Subgrade soils should consist of stiff native soils and the wall should be founded on a crushed rock leveling pad a minimum of 6 inches thick. Googride should bo spaced according to the attached wall detail. The bottom geogrid should be placed between the first and second block and subsequent geogrids should be spaced every three blocks vertically, The geogrids should be a minimium length of 7 feet measured from the face of wall. For walls less than 6 feet in retained height, geogrids should be a minimium length of 5 feet measured from the face of wall. Geogrid should consist of Tenser UXK1400, StrataGrid 8G300, or approved equivalent geotextile with d minimum ultimate tensile strength of 3,400 lbs/ft. The reinforced soil zone should consist of well drained granular fill approved by the wall engineer and should be compacted to at least 95% of Standard Proctor (ASTM 1)698). Finished slope above the wall should be leveled to.2H:1 V or less. The wall should be embedded a minimum of 6 inches below finished grade. The wall should be battered to 4.4 degrees, which corresponds to alternated pin positions between blocks. Adequate drainage behind and heneath the wall is critical to wall performance. A minimum 12 - inch thickness (measured horizontally) of free - draining sand and gravel, or drain rock, should be placed between the back of the wall facing units and backfill soils as shown on Figure 1. A subsurface drain consisting of 4 - inch diameter, perforated, Schedule 40 PVC or ADS Highway Grade pipe embedded in a clean, free draining sand and gravel, or drain rock, should be placed as shown on Figure 1. The drainpipe and surrounding drain rock should be wrapped in non - woven geotextile (Mirafi 140N, or approved equivalent) to minimize the potential for clogging and/or ground loss due to piping. Water collected from the drains should be directed to the storm system or other suitable out -t. j 7312 SW Durham Rood Tel (50S) 599.8445 Portland. 02400n 97224 Fats (609) SOQ -8705 08/121a1014 15: 5035988705 GEOPACIFIC ENG INC PAGE 02/10 Project No, 03 -8272 Atlanta Building Keystone Wall Based on the attached calculations, the proposed walls will have adequate factors of safety against sliding, overturning, bearing capacity failure, internal failure, and facing failure provided that our recommendations for wall construction are followed. Cement masonry unit blocks and geogrids should be installed per the manufacturer's instructions. GeoPacific should perform the special inspection for the construction of the designed Keystone walls including subgrade and backcut inspection, overexcavation requirements, embedment, wall batter, geogrid placement, and backfill compaction. We trust this information meets your needs. Please call if you have any questions. Sincerely, GeoPacific Engineering, Inc. gr 1P � �� Sslo ti ; / ter" /f OREGON 0 James D. Imbrie, P.E.. C.E.G. Geotechnical Engineer Attachments' Wall Typical Detail Design Calculations EJK ,ti Page 2 CIO/ 1 L! LG174 1: 7G 7G37 / G7 UGUI"'H1, 11' 1 V GIVU 11Vt., r"HUt G.3/ I. G C • 7312 3W Durham Road ee ����e���v® TYPE WALL ® Portland, Oregon 97224 I ' ingtnr6,11,`g urcv = Tel 503.598.8445 Fax 503.598.8705 TYPICAL DETAIL 4' ®8 2H:1V Maximum Finished Grade A, Keystone Cap Untl q �,q , VI.. 3 + ` h z tl�rg ( Minimum 8" Low Permeability Soil ( 1 r Y {• ti Y C c or .Px , om ' pa .1, Standard S . . „ unit Drainage Fill Keystone , .- Unit6 r 3J4 Crush Rock or Stone B' Maximum y/ "s Wall Height (H) , r'r 'di - , F 4 - . , . - Reinforced Soil Zone .- y mss= 3/4"-O BackfUl or Approved ^°r ` Equivalent Compacted to 95% of Standard Proctor li 414 Stitt Native Soil ° r: { I a I . l oogrid Min. Length - Fr + x (5Ft for Walls a 6Ft High) Limit of Excavation (Contractor Responsible t ®" Min , + -�" 4" Drain / for Stable Baekcut) P Approved c-- :_m , Drain Rock Unreinforced Concrete I or Cmshad Rock i Leveling Pad i 'TOTES: 1, Wall Height (H) Is the total height from top to bottom, 1 2. Minimum wall embedment is 6 inches for walls up to 8 feel in retained height. i 3. Unit core fill, leveling pad, and any additional drainage materials (see Note 5) shall consist of 3/4" - 0 crushed aggregate, I 4. Beckfill In reinforced zone to consist of 3/4 "-0 crushed rock or imported granular soil as approved by the geotechnical engineer.; t5. Geotechnicsl Engineer should review subgrade soils and cut slope behind wall. ;6. Geogrids must be of appropriate type and length per the design calculations. Dote: 08111/04 i i7. Finish grade must provide positive drainage. Drawn by: EJK i Project: Atlanta Building Tigard, Oregon Project No. U3 A i FIGURE 3 li /1 vv. ar. a.+v� r.+. ..rte �.y,_..J .,v •. yr ��..� r+U a� ry 4-. ice. ai.� I 1 UY I 1V • • SRWa11 ever 3.22 April 2002) Page 1 LN 030304229 ,Licensed to: Scott Hardman • 7312 SW Durham Road Portland OR 97224 ,License Njbber: 030304229 rd nrification: Project Name: Atlanta Building Section: Data Sheet: Owner: Client: Rell.agew Builders Prepared by: EJK Date; 08/1l/04 Time: ace file: \ \sewer \shared \jobs \projects 2001 = 5115- 2593 \03 - 8272 atlanta at office buildin ,\827:{ atlaata bldg keymtone eft conga= Tyne of Structure: oaosyntbetia- Reinforced Segmental Retaining wall Aesivn Mpthodolcav: MC= Method A Zahn],. e lle2 vviti D . a i) a 12.4k Ground Acceleration (PGA) ratio 0.00 Wall Geometry Design Wall Height (ft) 8.67 Embedment Wall Height (ft) 0.5 Exposed Design wall Meight (it) 8.17 Vertical Wall Height including Cap Unit (ft) 9.0 Exposed Wall Height including Cap Unit (ft) 8.5 Minimum Levelling Pad Thickness (ft) 0.5 Number of Segmental Wall Units 13 Hinge Height (ft) 8.67 Wall Inclination (degrees) 4.4 { VCI IGILUVY LJ. JU JU:J -JVur U.) VL Vf'hi.+lf "l+_r LIIS 11�1r r"HLL UJ /lU SRWa1I (ver 3.22 April 2002) Page 2 LN 030304229 dopes: Front Slope (degrees) horizontal Back Slope (degrees) 26.5 Infinite Dock Slope .Uniformly D7 c rt huted urchar.. Live Load Surcharge. none Dead Load Surcharge no7e Friction. Cohesion Angle Unit Weight Soil De a: Soil Description: lave) ( degreec) (pcf) Reinforced Soil Crushed Rock Engineered Fill N/A 36.0 130.0 Retained Soil Native Stiff Silt N/A 32.0 120.0 Levelling Pad Soil Crushed Rock N/A 36.0 130.0 Foundation Soil Stiff Silt 100.0 30.0 120.0 . SeCment01 Unit NamP: Segmental Unit Data: Cap Height (in) 4.0 Unit Height (xu)(in) 0.0 Unit Width (Wu)(in) 12.0 unit t,angth (in) 16.0 Setback (in) 0.615 Weight (infilled) (lbs) 114.0 Unit Weigbl (infilled) (pcf) 114.0 Center of Gravity (in) 6.0 e e^ta1.....Anit Interface shpAr Data Properties Ultimate Strength Criteria Service State Criteria Minimum (lb3 /ft) 769.0 769.0 Friction Angle (degrees) 26.9 26.9 Maximum (lbs /ft) 2598.0 2598.0 Geo:Inthetic Reinforcement Tspes and Number: Type Number Name 1 0 Tensor U2U 1400 2 0 6trateorid 60500 1 3 4 Strategrid 60300 1 U / 1L /LGCJ4 1D.OU 0053 00 /✓J� UtUrMLII Jl tNU 1Nl f H[at Fib /10 SRWa11 (ver 3.22 April 2002) page 3 Litt 030304229 tagar] th ics Prpr er f tes hzenrrth 4nd Polymer Tyne Type 1 Type 2 Type 3 Ultimate Strength (thfi /ft) 4720.0 5000.0 3600.0 Polymer Type I3tiPE or PP =PE or PP I38PE or PP fedur.t. *son PQCtPW..; Type 1 Type 2 Type 3 Creep 2.15 3.15 2.15 Durability 1.10 1.10 1.10 Installation Damage 1.20 1.05 1.05 Overall Factor of Safety 1.50 1.50 1.50 rengra: Type 1 ^ Type 2 Type 3 Ta (lba /ft) 1108.76 1342,33 912.78 Coeff_ r err t' of Tnr rs r i,,,, . Typ 1 Type 2 Type 3 Ci 0.8 0.8 0.8 Ccofticient_of Aireot S1ic3ing..; Type 1 Type 2 Type 3 Cds 0.7 0.8 0.8 Connection St - enatb: Type 1 Tyl./ 2 Type 3 U1timaftp R Criterion: Minimum (lbs /ft) 700.0 700.0 545.0 Friction Angle (degrees) 32.0 26.2 27.3 Maltimum (lbs /ft) 2600.0 2381.0 1739.0 Service State Criterion: Minimum (1bs /ft) 700.0 400.0 457.0 Friction Angle (degrees) 26.4 12.3 17.0 Maximum (1bs /ft) 2200.0 1147.0 1164.0 erfaep Shear Strength: Type 1 Type 2 Type 3 Ultimate Strength Criterion: Minimum (lbs /£t) 769.0 763.0 769.0 Friction Angle (degrees) 26.9 26.9 26.9 Maximum (lbs /ft) 2598.0 2598.0 2598.0 0 Service State Criterion: Minimum (lbs /ft) 769.0 769.0 769.0 I Friction tangle (degrees) 26.9 26.9 26.9 Maximum (lbe/ft) 2596.0 2598.0 2590.0 • uoricrcau4 a7.Ju Z.1[1.57:7700(00 umurmuirIL. tnla in1; YRlat btf /lb SRWa11 (ver 3.22 April 2002) Page 5 LW 030304229 SRW Heel Gensynhheric Fos ros shear 1'OS Unit Elev Type Over - Shear (deformation Cdef N (ft) turning Connection (defoo on) 4 (Aeak} (peak) > 1.3 a 1.5 < 0.03 n nu s 1.9 < 0.75 in • 13 8.0 none 19.72 93.11 OK 12 7.33 none 5.19 24.3, on 11 6.67 3 2.42 11.33 OK 3.77 10 6.0 none 5.0 - 0K 9 5.33 none 4.62 23.35 OK - - 6 4.67 3 3.87 7.32 OR 2.5 OK 7 4.0 none 3.99 - - - 6 3.93 none 3.71 16.03 OR 4 2.67 a 3.34 2.4 OR 1.92 OR 4 2.0 none 3.26 - _ - 3 1.33 none 3.1 12.8 OR 2 0.67 3 2.62 4.21 OR 1.39 ox 1 0.0 none 2.8 - - ffote: Calculated values MEET ALL design criteria lyres ,(!foment 4nA RhPar SRW Heel Geo Drive Resist Shear Shear Shear Unit E1ev Type Moment ' Moment Load Capacity Capacity M (ft) (1bs- fc /tt) (J.bs ft /fr) (lbs/ft) (lbs /ft) (Ibs /fe) • *out - (peak) (deformation) 13 6.0 none 1.9 38.0 0.7 807.6 807.6 12 7.33 none 15.4 79.9 34.7 886.1 846.1 11 6.67 3 52.0 125.7 78.1 804.7 094.7 10 6.0 mono 123.4 617.2 - 88.9 983.2 943.2 9 5.33 norm 240.9 1112.5 41.2 961.8 961.8 6 4.67 3 416.3 1611.0 136.6 1000.3 1000.3 7 6.0 none 661.1 2635.3 - 62.0 1030.9 1036.9 6 3.33 none 986.8 3662.5 67.2 1077.5 1077.5 5 2.67 3 1405.1 4693.7 214.7 1116.0 1116.0 4 2.0 mono 1927.4 6327.4 -80.9 1154.6 1154.6 3 1.33 none 2565.8 7965.1 93.2 1193.1 1193.1 2 0.67 3 3330.5 9606.7 292.7 1231.7 1231.7 1 0.0 none 4234.5 11860.6 0.0 1270.2 1270.2 n An 1 eations): SRW Heel Geo Connection Connection Connection Unit Elev Type Load Capacity Capacity fi (ft) abs /t%) (peak) ( oerormation) (lbs /ft) fibs /ft) 11 6.67 3 175.6 662.7 526.7 0 4.67 3 312.2 780.4 596.4 5 2.67 3 460.4 898.0 666.1 2 (1.67 2 503.6 7.015.7 735.0 ij 40 ,� , a e �......� aJ. J�J JVJJ JVV r VJ VC Vf�I -Il,lr 14 CIYV 11*, rut= 13 I lb SRWa11 (ver 3.22 April 2002) zN 030304229 Page 6 4.4 degrees 8.67 ft 9.0 ft F i n - • - - - • - - - StrataGrid SG300 • — - — - — - — - — _-° StrataGrid SG300 _ I - - - — • — — • - - — StrataGrid SG300 0.5 ft - — . — . — • — . — StrataGrid SG300 T -0.5 f t 7.0 ft Prciec i6 Tclant ification: Project Name • Atlanta. Building Section: Data Sheet: Owners Client: Es1inger Builders Prepared by:EJK Date: 08/11/001 Time: It Data fi 7a \0server\sharedajoTe®i rc3 cte 2003 - 0115- 8s93e03- 0272 - aslant at office buil• \8272 '.r -_ oPacific x EngiReeHng,lnec May 19, 2003 Real -World Geotechnical Solutions • Investigation • Design Project No. 03 -8272 • Construction Support Eslinger Builders, Inc. 11575 SW Pacific Hwy, PMB 160 ;.! Tigard, OR 97223 S ,- D ,pc I _ 00 0 Z3 Attn: Malcolm Eslinger (Fax 503 - 620 -9475) (p '3C) 5v✓ A-1 ST' RE: GEOTECHNICAL REVIEW ATLANTA STREET OFFICE BUILDING TIGARD, OREGON Reference: GeoPacific Engineering, Inc., Foundation Investigation, Baylor Court Office Building, Tigard, Oregon, 16 pages, 7 figures, dated May 23, 2001. AKS Engineering and Forestry, Preliminary grading and erosion control plan (sheet 3 of 6), Preliminary Utility plan (sheet 4 of 6), scale 1 inch equals 10 feet, dated October 25, 2002. This letter presents the results of our geotechnical review of the proposed office building project located at the southwest corner of the intersection of Atlanta Street and SW 68th Parkway in Tigard, Oregon. The scope of our review included: (1) review of our geotechnical report for the adjacent building, (2) site reconnaissance, (3) review of excavations at the site during site demolition, and (4) preparation of this brief letter report. The approximate 0.35 -acre property is situated on a gentle, west - facing slope that inclines at about 10% to 20% grade. A localized road embankment fill slope inclining at about 45% grade is present along the eastern margin of the property. At the time of our site visit, existing structures including the swimming pool at the northwest corner had been demolished and removed from the site. The proposed development consists of a two -story, office building with wood framing and a slab -on- grade floor similar to the adjacent Baylor Court building. Building construction will incorporate continuous spread footings for walls and isolated spread footings for columns. We anticipate that wall loads will be on the order of 1,500 lbs. per lineal foot and interior column loads will be on the order of 35 kips. The project also includes placement of engineered fill up to 5 feet thick for paved parking areas, construction of an approximately 6- foot -high, keystone retaining wall along the western property line, and construction of an unspecified retaining wall beyond the southern wall of the building with a maximum height of 10 to 12.feet. An underground stormwater detention pipe is planned in the parking area. Based on review of shallow excavations, the proposed building site is underlain by a surficial layer of t old fill approximately 1 to 3 feet thick that rests on native, clayey silt soil. Based on hand probe measurements, observed native clayey silt soil is generally stiff to very stiff. We anticipate that (i . limited amounts of hard, basalt may be encountered along the eastern wall of the building where 7312 SW Durham Road Tel (503) 598 -8445 Portland, Oregon 97224 Fax (503) 598 -8705 • Project No. 03 -8272 `' Atlanta Office Building cuts of up to 12 feet are planned. In a test excavation, no basalt was encountered to a depth of 7 feet below existing grade. CONCLUSIONS AND RECOMMENDATIONS Our geotechnical review indicates that the proposed development is geotechnically feasible provided that our recommendations are incorporated into the design and construction of the project. The conclusions and recommendations of the above - referenced geotechnical report for the adjacent Baylor Court site are applicable to the project site with the following exceptions and /or amendments. Based on review of shallow excavations and the planned finish floor elevation, we anticipate that the building foundation will bear primarily on native, clayey silt soil. The allowable soil bearing capacity for stiff, native soil and /or engineered fill may be taken as 2,000 lbs /ft Localized overexcavation of old fill or soft soils and replacement with engineered backfill may be necessary to provide adequate soil bearing strength. We anticipate that limited amounts of hard, basalt may be encountered along the eastern wall of the building where cuts of up to 12 feet are planned. GeoPacific Engineering should inspect the foundation excavation to verify adequate bearing strength prior to foundation construction. It is our understanding that the planned retaining wall that extends beyond the southern wall of the building will connect with the existing keystone wall on the Baylor Court building site. The portion of this wall that extends close to the right -of -way for SW 68 Parkway may be difficult to construct as shown due to space constraints. Minor slope movement of the road embankment fill as evidenced by reported curb settlement suggests that this fill may be poorly compacted. Hence, temporary shoring may be necessary to support excavation walls during construction. Relocating the wall farther from the right -of -way or utilizing a narrower type of wall would help to mitigate the need for shoring. For areas to receive engineered fill, any remaining old fill should be removed prior to engineered fill placement. Removals should be verified by Geo Pacific. GeoPacific will be happy to provide field inspection services for the project as the geotechnical engineer of record. UNCERTAINTY AND LIMITATIONS We have prepared this report for the client, for use on this project only. The report should be provided in its entirety to prospective contractors for bidding and estimating purposes; however, the conclusions and interpretations presented in this report should not be construed as a warranty of the subsurface conditions. Inconsistent conditions can occur between explorations that may not be detected by a geotechnical study. Within the limitations of scope, schedule and budget, GeoPacific attempted to execute these services in accordance with generally accepted professional principles and practices in the fields of 't geotechnical engineering and engineering geology at the time the report was re 9 9 9� 9 9 9Y P prepared. No warranty, express or implied, is made. The scope of our work did not include flood hazard, -2- Project No. 03 -8272 Atlanta Office Building environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous or toxic substances in the soil, surface water, or groundwater at this site. We appreciate this opportunity to be of service. If you have any questions, please call. Sincerely, GeoPacific Engineering, Inc. . Ca e ' 4, ,, (421144* A ‘' , r 15 4-N \ `ti �i, C:,ti u. �� 14743 r � iNIMMM/LI..11.. /1'‘ / /4-:- E1766 k. OREGON FF Rrtvo o °� v4 4, , 'N‘'" •1 � L c)3 ��L3� Paul A. Crenna, C.E.G. James D. Imbrie, P.E., C.E.G. Engineering Geologist Geotechnical Engineer Cc: Alex Hurley, AKS Engineering (Fax 503 - 925 -8969) - 3 - r • GeoPacific Engineering, inc. Real -World Geotechnical Solutions Investigation a Design a Construction Support May 23, 2001 Project No. 01 -7282 Eslinger Builders, Inc. 11575 SW Pacific Highway Tigard, OR 97223 Attention: Chad Eslinger (Fax 503 - 245 -9908) RE: FOUNDATION INVESTIGATION BAYLOR COURT OFFICE BUILDING TIGARD, OREGON This report presents the results of a geotechnical foundation investigation conducted by GeoPacific Engineering, Inc. for the proposed Baylor Court office building located in the City of Tigard, Washington County, Oregon. The primary purpose of our investigation was to evaluate subsurface conditions at the site and provide geotechnical recommendations for foundation design and construction. GeoPacific's work was performed in accordance with our proposal No. P1321, dated } April 24, 2001. Authorization to begin the proposed scope of work was given by Chad Eslinger via fax on May 3, 2001. BACKGROUND INFORMATION Project Information 1 _ Location: The site includes one parcel with a total size of 0.37 acres that borders SW 68 Parkway and Baylor Court in the City of Tigard, Washington County, Oregon (Figure 1). Owner/ Eslinger Builders, Inc. Developer: 11575 SW Pacific Highway, Tigard, Oregon 97223 Architect: Robert Evenson Associates 6249 SW Canyon Court, Portland, Oregon 97221 Civil AKS Engineering and Forestry Engineer: 13910 SW Galbreath Drive, Suite 100, Sherwood, Oregon 97140 Structural James G. Pierson, Inc. Engineer: 320 SW Stark, Suite 535, Portland, Oregon 97204 Jurisdictional Agency: City of Tigard, Oregon 17700 SW Upper Bowies Ferry Road, Suite 100 Tel (503) 598 -8445 Portland, Oregon 97224 Fax (503) 598 -8705 Page 1 • GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court SITE DESCRIPTION AND PROPOSED DEVELOPMENT The subject property is a 0.37 acre parcel situated on a gentle slope inclining to the west at about 16% grade. The elevation of the site ranges between 310 and 331 feet above mean sea level. Vegetation on the site consists of sparse trees and brush. The proposed development is a two- story, commercial building with an approximate footprint area of 2,700 ft (Figure 2). Building construction will incorporate wood framing, a slab -on -grade floor, isolated spread footings for columns, and continuous spread footings for load bearing walls. The eastern perimeter of the foundation will include a maximum 10- foot -high retaining wall. The project structural engineer indicates that interior column loads will be approximately 33 kips, and that wall loads will be about 1,200 lbs per lineal foot. Paved parking and driveways are planned on the western and northwestern margins of the site. We understand that the project will include excavation and limited placement of engineered fill to create a near level parking area. The grading plan shows a maximum fill thickness of about 4 feet. SITE GEOLOGY The subject site is underlain by the Quaternary Willamette Formation, a catastrophic flood deposit associated with repeated glacial outburst flooding of the Willamette Valley during the last 1.6 million years (Madin, 1990). The last of these outburst floods occurred about 10,000 years ago. In the Tualatin basin, these deposits consist of horizontally layered, micaceous, silt to coarse sand forming poorly- defined to distinct beds less than 3 feet thick. Regional studies estimate the thickness of Willamette Formation in the vicinity of the subject site to be less than 5 feet (Madin, 1990). Underlying the Willamette Formation is the Plio- Pleistocene age (1 to 2 million years old) Boring Lava (Madin, 1990). The Boring Lava consists mainly of basaltic lava flows, but locally contains tuff breccia, ash, tuff, cinders, and scoriaceous volcanic debris flows deposited on the flanks of volcanic cones. The lava flows are commonly light gray to nearly black, with lighter tones predominating, and are characterized by columnar jointing and flow structures. SUBSURFACE CONDITIONS On May 11, 2001, GeoPacific explored subsurface conditions on the site by excavating five test pits and conducting two portable dynamic cone penetrometer tests at the locations shown in Figure 2. The explorations were located in the field by pacing distances from apparent property corners and other site features. As such, the locations of explorations should be considered approximate. Field exploration methodology is discussed in Appendix A, which also contains logs of the test pits. The observed conditions and soil properties are summarized below. Fill: A road embankment fill for SW 68th Parkway with an estimated thickness of 2 to 6 feet underlies the eastern edge of the site. In TP -1, 1 foot of fill was encountered at the SW corner of the proposed building. This fill consisted of loose rock fragments and silt with abundant organic material. Page 2 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court Topsoil: The ground surface is directly underlain by a thick topsoil horizon consisting of dark brown, organic SILT (ML -OL) with abundant roots and other organic material. Our explorations indicate that the thickness of topsoil on this site ranges from 8 to 12 inches. Soil B- Horizon Grading to Willamette Formation: Underlying the topsoil is clayey SILT (ML) forming a clay - enriched soil B- horizon. In general, the clayey silt is stiff to very stiff. Pocket • - penetrometer measurements indicate an approximate unconfined compressive strength of 1.5 to 3.5 tons /ft In test pits, the thickness of this layer ranges from 1.3 to 2.3 feet. The soil B- horizon grades down to the parent material, the Willamette Formation, at some locations on the site. The Willamette Formation consists of a light brown, uniform, clayey SILT (ML). The SILT is generally very stiff to hard. Pocket penetrometer measurements indicate an unconfined compressive strength of 2.5 to 4.5 tons /ft In test pits, the thickness of the Willamette Formation ranges from 0 to 3.5 feet. Boring Lava: Underlying the Willamette Formation is basalt bedrock belonging to the Boring Lava geologic unit. Shallow basalt was encountered in test pits TP -1 through TP -4 at a depth of 2.5 to 6 feet (Figure 2). Practical refusal with an 8 -ton trackhoe occurred on hard (R4) basalt at depths of 2.5 to 6.5 feet (see Table 1). Commonly, a 1- to 3- foot -thick zone of highly weathered and fractured, soft basalt with hard basalt boulders was encountered before reaching the depth of practical refusal. Soil Moisture and Groundwater • On May 11, 2001, soil moisture conditions observed in test pits ranged from dry to moist. No - significant groundwater was encountered in test pits to a maximum exploration depth of 6.5 feet. Common soil mottling and clay leaching indicates that shallow, seasonal perching of groundwater in the upper several feet of soil occurs during periods of prolonged rainfall. SEISMIC SETTING At least three major fault zones capable of generating damaging earthquakes are known to exist in the vicinity of the subject site. These include the Gales Creek - Newberg -Mt. Angel Structural Zone, the Portland Hills Fault Zone, and the Cascadia Subduction Zone. Gales Creek - Newberg -Mt. Angel Structural Zone The Gales Creek - Newberg -Mt. Angel Structural Zone is a 50- mile -long zone of discontinuous, NW- trending faults that lies about 15 miles southwest of the subject site. These faults are recognized in the subsurface by vertical separation of the Columbia River Basalt and offset seismic reflectors in the overlying basin sediment (Yeats et al., 1996; Werner et al., 1992). A geologic reconnaissance and photogeologic analysis study conducted for the Scoggins Dam site in the Tualatin Basin revealed no evidence of deformed geomorphic surfaces along the structural zone (Unruh, 1994). No seismicity has been recorded on the Gales Creek or Newberg Faults; however, these faults are considered to be potentially active because they may connect with the seismically active Mount Angel Fault (the fault segment closest to the site) and the rupture plane of the 1993 M5.6 Scotts Mills earthquake (Werner et al: 1992; Geomatrix Consultants, 1995). Page 3 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court Portland Hills Fault Zone The Portland Hills Fault Zone is a series of NW- trending faults that vertically displace the Columbia River Basalt by 1,130 feet and appear to control thickness changes in late Pleistocene (approx. 780,000 years) sediment (Madin, 1990). The fault zone extends along the eastern margin of the Portland Hills for a distance of 25 miles, and lies about 7 miles northeast of the subject site. Geomorphic lineaments suggestive of Pleistocene deformation have been identified within the fault zone, but none of the fault segments have been shown to cut Holocene (last 10,000 years) deposits (Balsillie and Benson, 1971: Cornforth and Geomatrix Consultants, 1992). No historical seismicity is correlated with the mapped portion of the Portland Hills Fault Zone, but in 1991 a M3.5 earthquake occurred on a NW- trending shear plane located 1.3 miles east of the fault (Yelin, 1992). Although there is no definitive evidence of recent activity, the Portland Hills Fault Zone is judged to be potentially active (Geomatrix Consultants, 1995). Cascadia Subduction Zone The Cascadia Subduction Zone is a 680- mile -long zone of active tectonic convergence where oceanic crust of the Juan de Fuca Plate is subducting beneath the North American continent at a ,rate of 4.5 cm per year (Goldfinger et al., 1996). Very little seismicity has occurred on the plate interface in historic time, and as a result, the seismic potential of the Cascadia Subduction Zone is a subject of scientific controversy. The lack of seismicity may be interpreted as a period of quiescent stress buildup between large magnitude earthquakes or as being characteristic of the long -term behavior of the subduction zone. A growing body of geologic evidence, however, strongly suggests that prehistoric subduction zone earthquakes have occurred (Atwater, 1992; Carver, 1992; Peterson et al., 1993; Geomatrix Consultants, 1995). This evidence includes: (1) buried tidal marshes recording episodic, sudden subsidence along the coast of northern California, Oregon, and. Washington, (2) burial of subsided tidal marshes by tsunami wave deposits, (3) paleoliquefaction features, and (4) geodetic uplift patterns on the Oregon coast. Radiocarbon dates on buried tidal marshes indicate a recurrence interval for major subduction zone earthquakes of 250 to 650 years with the last event occurring 300 years ago (Atwater, 1992; Carver, 1992; Peterson et al., 1993; Geomatrix Consultants, 1995). The inferred seismogenic portion of the plate interface lies roughly 55 miles west of the subject site. SEISMIC GROUND FAILURE HAZARD A variety of slope and ground failures can occur in response to intense seismic shaking during large magnitude earthquakes. These failures are usually related to the phenomena of liquefaction, the process by which water - saturated sediment changes from a solid to a liquid state during seismic shaking. Since liquefied sediment may not support the overlying ground, or structures built thereon, a variety of failures may occur including lateral spreading, landslides, ground settlement, cracking, sand boils, oscillation lurching, etc. The conditions necessary for liquefaction to occur are: (1) the presence of poorly consolidated, cohesionless sediment, (2) saturation of the sediment by groundwater, and (3) an earthquake that produces intense seismic shaking (generally a Richter Magnitude greater than M5.0). In general, older, more consolidated sediment, clayey or gravelly sediment, and sediment above the water table will not liquefy (Youd and Noose, 1978). Page 4 1 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court We consider the subject site to have a negligible susceptibility to liquefaction due to the presence of shallow hard basalt and the absence of shallow groundwater. CONCLUSIONS AND RECOMMENDATIONS Our investigation indicates that the proposed commercial development is geotechnically feasible provided that the following recommendations are incorporated in the design and construction phases of the project. Heavy equipment will be necessary to achieve the planned excavation depths into hard basalt. We anticipate that excavation depths of greater than 4 to 6 feet will require heavy ripping with rock buckets or bulldozer ripper teeth and /or use of pneumatic rock chipper attachments. Blasting may be necessary in the deeper portion of the planned excavation. Site Preparation All areas to be graded should first be cleared of debris, trees, stumps, vegetation, etc., and all debris from clearing should be removed from the site. Organic -rich topsoil and fill should then be stripped. We anticipate that an average stripping depth of 6 to 8; inches will be necessary to remove organic - rich topsoil. Deeper stripping, or tilling and root - picking, to depths of 1 to 2 feet will be necessary to remove tree roots. The final depth of stripping removal will be determined on the basis of a site inspection after the initial stripping has been performed. The majority of the stripped topsoil should be removed from the site; while the remaining topsoil should only be stockpiled in designated areas. Stripping operations should be observed and documented by the geotechnical engineer or his representative. Rough Grading The project will include excavation of a building pad and limited grading for construction of a near level parking area. All grading should be performed as engineered grading in accordance with Appendix Chapter 33 of the 1997 Uniform Building Code (UBC) with the exceptions and additions noted herein. Proper test frequency and earthwork documentation usually requires daily observation and testing during stripping, rough grading, and placement of engineered fill. Fill may consist of suitable on -site soils or imported material. Imported material must be approved by the geotechnical engineer prior to its arrival on site. Oversize material greater than 6 inches in size should not be used within 3 feet of foundation footings, and material greater than 12 inches in maximum dimension should not be used in engineered fill. Engineered fill should be compacted in horizontal lifts not exceeding 8 inches using standard compaction equipment. We recommend that engineered fill be compacted to at least 90% of the maximum dry density determined by ASTM D1557 (Modified Proctor) or equivalent. Field density testing should conform to ASTM D2922 and D3017, or D1556. Engineered fill should be observed and tested by the project geotechnical engineer or his representative. Typically, one density test is performed for at least every 2 vertical feet of fill placed or every 500 yd whichever requires more testing. Because testing is traditionally performed on an on -call basis, we recommend that the • earthwork contractor be held contractually responsible for test scheduling and frequency. Page 5 4 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court Earthwork is usually performed in the summer months, generally mid -June to mid - October, when warm, dry weather facilitates proper moisture conditioning of soils. Earthwork performed during the wet - weather season will probably require expensive measures such as cement treatment or imported granular material to compact fill to the recommended engineering specifications. Erosion Control Due to the presence of gentle slope gradients and adjacent development, we consider the potential for adverse erosion during construction to be moderate. The contractor should implement the project erosion control plan conscientiously. We recommend that cut and fill slopes be seeded or planted as soon as possible after construction, so that vegetation has time to establish itself before the onset of the next wet - weather season. { Excavating Conditions and Temporary Excavations Subsurface test pit exploration indicates that shallow basalt underlies the site at depths of 2.5 to 6.5 feet (Figure 2). Practical refusal with a medium -sized trackhoe (8 -tons) occurred on hard basalt (R4) at a depth of 4 to 6 feet (see Table 1). We anticipate that excavation depths of greater than 4 to 6 feet will require heavy ripping with rock buckets or bulldozer ripper teeth, and /or use of pneumatic rock chipper attachments, and possibly blasting. Table 1 - Rock Hardness Classification Chart ODOT Field Criteria Unconfined Typical Equipment Needed For Rock Hardness Rating Compressive Strength Excavation Extremely Soft (RO) Indented by thumbnail <100 psi Small hoe . Scratched by thumbnail, Very Soft (R1) crumbled by rock hammer 100 -1,000 psi Small hoe Not scratched by Medium Hoe Soft (R2) thumbnail, indented by 1,000 -4,000 psi (slow digging with small hoe) rock hammer Medium to large hoe (slow to very Scratched or fractured by slow digging), typically requires Medium Hard (R3) • rock hammer 4,000 8,000 Si p chipping with hydraulic hammer or • mass excavation) Hard (R4) Scratched or fractured w/ 5,000 16,000 psi Slow chipping with hydraulic difficulty hammer and /or blasting Not scratched or fractured Very Hard (R5) after many blows, hammer >16,000 psi Blasting rebounds Maintenance of safe working conditions, including temporary excavation stability, is the responsibility of the contractor. Actual slope inclinations at the time of construction should be determined based on safety requirements and actual soil and groundwater conditions. All temporary cuts in excess of 4 feet in height should be sloped in accordance with U.S. Occupational Safety and Heath Page 6 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court Administration (OSHA) regulations (29 CFR Part 1926), or be shored. In May of 2001, the existing native soils classified as OSHA Type A and B Soils. Vibrations created by traffic and construction equipment may cause some caving and raveling of excavation walls. In such an event, lateral support for the excavation walls should be provided by the contractor to prevent loss of ground support and possible distress to existing or previously constructed structural improvements. Foundations The proposed building site is suitable for shallow foundations bearing on native soil and basalt bedrock. Foundation design, construction, and setback requirements should conform to Chapter 18 of the UBC and Oregon Structural Specialty Code (OSSC). The recommended allowable soil bearing pressure for footings on native soil is 2,500 lbs/ft We estimate that a 4- foot - square footing supporting a 33 kip column load on native soil will experience an ultimate settlement of 0.75 inch. Similarly, the estimated ultimate settlement of a continuous, spread footing bearing on native soil and supporting a wall load of 1.2 kip per lineal foot is 0.5 inch. Settlement of footings on basalt will be negligible. Given the specified loads, foundation, and grade, we anticipate a maximum differential settlement of 0.5 inches over a distance of 25 feet. The recommended bearing pressure applies to the total load (dead + live loads), and may be increased by one -third for short -term loading produced by wind or seismic events. We recommend that continuous footings for load bearing walls have a minimum width of 18 inches. Actual footing widths, sizing, and reinforcement should be determined by the design Architect- or Engineer -of- Record. The coefficient of friction between native soil or engineered fill and poured -in -place concrete may be taken as 0.35 with no factor of safety added. The coefficient of friction between hard basalt and poured -in -place concrete may be taken as 0.5 with no factor of safety added. For protection against frost heave and maximization of bearing strength, we recommend that spread footings for two -story buildings be embedded at a minimum depth of 18 inches below exterior grade. All footing excavations should be trimmed neat, and all loose or softened soil should be removed from the excavation bottom prior to placing reinforcing bars. In order to verify subgrade strength, we recommend that GeoPacific perform a footing subgrade inspection prior to pouring concrete. Excavations near foundation footings should not extend within a 1 H:1 V plane projected downward from the bottom edge of footings. For wet - weather construction, we recommend that 4 inches of compacted, granular backfill be placed in the bottom of footing excavations immediately after excavation to protect the subgrade from water softening. Seismic Design Probabilistic assessments of the seismic shaking hazard in Oregon predict that in the next 50 years bedrock underlying the subject site has a 10% probability of experiencing a peak ground acceleration (PGA) of 0.20 g, a 5% probability of experiencing a PGA of 0.28 g, and a 2% probability of experiencing a PGA of 0.38 g (Geomatrix, 1995). Page 7 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court The project site lies within Seismic Zone 3, as defined in Chapter 16, Division IV of the 1997 Uniform Building Code (UBC). Seismic Zone 3 includes the western portion of Oregon, and represents an area of relatively high seismic risk. For comparison, much of California and southern Alaska are defined as Seismic Zone 4, which is an area of highest seismic risk. Consequently, moderate levels of earthquake shaking should be anticipated during the design life of the proposed improvements, and the structures should be designed to resist earthquake loading in accordance with the methodology described in the 1997 UBC and 1998 OSSC. Based on the subsurface conditions observed during our exploration program, UBC Soil Type SB may be assumed for the site. The corresponding seismic factors may be used in developing a normalized response spectrum for the assumed UBC Soil Type. In our opinion, the potential for liquefaction or liquefaction - related ground failure at the subject site is i negligible, and no special mitigating measures are recommended against liquefaction. Concrete Slabs -On -Grade For slab floor design, the allowable modulus of subgrade reaction may be taken as 150 lbs/in per inch. Underslab base rock should consist of 3 /4 " -0 crushed aggregate containing no more than 5% non- plastic fines passing the No. 200 (0.75 mm) sieve. For dry- weather construction, the minimum recommended base rock section for capillary break is 8 inches. The total thickness of crushed aggregate will be dependent on the subgrade conditions at the time of construction, and should be verified visually by proof - rolling. Underslab aggregate should be compacted to at least 95% of its maximum dry density as determined by ASTM D1557 or equivalent. For the post- construction state, the site does not appear to have high soil moisture co_ nditions relative to the Willamette Valley region; however, the project designer or owner may want to consider the following additional measures (listed in order of decreasing effectiveness) to further reduce the potential for damp floors and damage to moisture - sensitive flooring. (1) Maintain a slab water cement ratio of 0.42 or less utilizing mid -range plasticizers. (2) Thickening of the rock subgrade to a minimum of 12 inches and utilize clean rock with no more than 2% fines. (3) Sloping the subgrade soil away from the center of the slab at an approximate gradient of 1%. (4) Application of a moisture intrusion barrier on the slab (Preseal, Creteseal or approved) to the surface of the concrete while curing. (5) Placement of vapor barrier sheeting beneath the slab. Moisture barrier products should be installed in accordance with manufacturer recommendations. The building should be complete and the HVAC system operating for a period of time during wet- weather before moisture - sensitive flooring is applied. This time period should be long enough to allow the vapor gradient within and below the building to stabilize and obtain acceptable slab moistures. Page 8 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court Retaining Walls The average allowable bearing pressure for retaining walls may be taken as 2,500 lbs/ft with a maximum allowable toe pressure of 3,000 lbs/ft The coefficient of friction between native soil or • engineered granular fill and poured -in -place concrete may be taken as 0.35 with no factor -of- safety added. The coefficient of friction between basalt and poured -in -place concrete may be taken as 0.5. Recommended lateral soil pressures for design of permanent retaining structures with adequate drainage can be calculated using the equivalent fluid unit weights provided in Table 2. The effect of surcharges or live loads on lateral pressures has not been included. Adequate drainage is such that no hydrostatic pressures are realized behind the walls. The unit weights in Table 2 are for backfill consisting of free - draining granular material (crushed aggregate or sand); on -site soils are not recommended for retaining wall backfill. Wall backfill should be compacted to at least 90% of the maximum dry density determined by ASTM D1557 or equivalent. Table 2 - Recommended Equivalent Fluid Unit Weights for Calculating • Lateral Earth Pressures • Unrestrained Wall Restrained Wall Type Level Profile 2H:1V Upslope Level Profile 2H:1V Upslope Active Pressure (Ibs /ft2 /ft) 32 45 - - At -Rest Pressure (Ibs /ft /ft) - - 45 60 — Passive Pressure * 280 280 250 250 (Ibs /ft /ft) * Passive pressure values are allowable and include a factor of safety of 1.5. For passive pressure calculations, the upper 6 inches of embedment should be ignored. Subdrains should be installed behind all retaining walls to retard the build -up of adverse hydrostatic pressure. Subdrains should consist of a minimum 3 -inch diameter ADS Highway Grade (or equivalent), perforated, plastic pipe enveloped in a minimum of 3 ft per lineal foot of 2 "- 1/2", , open, graded, gravel (drain rock) wrapped with geofabric filter (Amoco 4545, Trevia 1120, or equivalent). A minimum one -half percent fall should be maintained throughout the drain and non - perforated pipe } outlet. For concrete retaining walls, waterproofing and a geocomposite wall drain . such as Contech C -DRAIN 11K, or equivalent are recommended to minimize the potential for interior moisture problems. Footing Drains A perimeter footing drain is recommended around the building foundation. Perimeter drains should consist of a minimum 3 -inch diameter Schedule 40 or ADS Highway Grade, perforated, plastic pipe enveloped in a minimum of 1 ft per lineal foot of 2 "- 1 /2 ", open, graded gravel (drain rock) wrapped with geofabric filter (Amoco 4545, Trevia 1120, or equivalent). A minimum one -half percent fall should be maintained throughout the drain and non - perforated pipe outlet. Footing drains may be eliminated when redundant to wall subdrains. { Page 9 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court Utility Trenches PVC pipe should be installed in accordance with the procedures specified in ASTM D2321. We recommend that structural trench backfill be compacted to at least 90% of the maximum dry density obtained by Modified Proctor ASTM D1557 or equivalent. Initial backfill lift thicknesses for a 3 /4 " -0 crushed aggregate base may need to be as great as 4 feet to reduce the risk of flattening underlying flexible pipe. Subsequent lift thicknesses should not exceed 1 foot. Typically, one density test is taken for every 4 vertical feet of backfill on each 200 - lineal -foot section of trench. If imported granular fill material is used, then the lifts for large vibrating plate- compaction equipment (e.g. hoe compactor attachments) may be up to 2 feet, provided that proper compaction is being achieved and each lift is tested. Use of large vibrating compaction equipment should be carefully monitored near existing structures and improvements due to the potential for vibration - induced damage. Pavement Design Portable Dynamic Cone Penetrometer (PDCP) test results were used to approximate the California Bearing Ratio (CBR) of in -situ, on -site soils. PDCP field tests indicate a CBR for near surface soil generally ranging between 4 and 10 (Appendix A). For design purposes, we used a CBR of 5 for in- situ, native soil. Empirical correlations between CBR and resilient modulus (M indicate that the native soil has an approximate resilient modulus of 7,500 lbs/in (CBR =5). Table 3 presents our recommended minimum pavement section for dry- weather construction. This design was formulated using the Crushed Base Equivalent method, a traffic index of 4.0, and is in general accordance with flexible pavement design methods prescribed by AASHTO for light -duty pavement with a design life of 20 years. Generally, one subgrade, one base course, and one asphalt compaction test is performed for every 100 to 200 linear feet of paving. Table 3 - Recommended Minimum Dry - Weather Pavement Section Material Layer Driveways (in.) Auto Parking Compaction Standard Areas (in.) Asphaltic Concrete (AC) 3 2.5 91% of Rice Density AASHTO T- 209 Crushed Aggregate Base 3 /4 "- 95% of Modified Proctor 0 (leveling course) 2 AASHTO T -180 Crushed Aggregate Base 6 95% of Modified Proctor 1'/z " -0 6 "-0 T -180 Areas of yielding, native soil subgrade should be tilled to a minimum depth of 12 inches, aerated, and recompacted in -place to at least 90% of the maximum dry density obtained by ASTM D1557 or equivalent. GeoPacific recommends that subgrade strength be verified visually by proof - rolling directly on soil subgrade with a loaded dump truck during dry weather and on top of base course in wet weather. Soft areas that rut, pump, or weave by more than 1/4 inch should be stabilized prior to paving. Page 10 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court If pavement areas are to be constructed during wet weather, GeoPacific should review the subgrade and proposed construction methods immediately prior to the placement of base course so that specific recommendations can be provided. Wet- weather pavement construction is likely to require soil amendment, or woven geotextile fabric and an additional 6 inches of crushed aggregate base. UNCERTAINTY AND LIMITATIONS We have prepared this report for the developer and designers, for use on this project only. The report should be provided in its entirety to prospective contractors for bidding and estimating purposes; however, the conclusions and interpretations presented in this report should not be construed as a warranty of the subsurface conditions. Experience has shown that soil and groundwater conditions can vary significantly over small distances. Inconsistent conditions can occur between explorations that may not be detected by a geotechnical study. If, during future site operations, subsurface conditions are encountered which vary appreciably from those described herein, GeoPacific should be notified for review of the recommendations of this report, and revision of such if necessary. We recommend that GeoPacific be retained to review the plans and specifications and verify that our recommendations have been interpreted and implemented as intended. Sufficient geotechnical monitoring, testing and consultation should be provided during construction to confirm that the conditions encountered are consistent with those indicated by explorations. The checklist attached to this report (Appendix B) outlines recommended geotechnical observations and - testing for the project. Recommendations for design changes will be provided should conditions revealed during construction differ from those anticipated, and to verify that the geotechnical aspects of construction comply with the contract plans and specifications. Within the limitations of scope, schedule and budget, GeoPacific attempted to execute these services in accordance with generally accepted professional principles and practices in the fields of } geotechnical engineering and engineering geology at the time the report was prepared. No warranty, express or implied, is made. The scope of our work did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous or toxic substances in the soil, surface water, or groundwater at this site. Page 11 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court Sincerely, 'GEOPACIFIC ENGINEERING, INC. a . , ER s '0 Tdr git" 3 E1766 r OREGON FR/NG GE Z 23. 1 �, Paul A. Crenna, C.E.G. James D. Imbrie, P.E., C.E.G. Principal Engineering Geologist Principal Geotechnical Engineer Attachments: Figure 1 — Location Map Figure 2 — Site Plan and Explorations Appendix A — Field Explorations, Sampling and Laboratory Testing Appendix B — Checklist of Recommended Geotechnical Observation and Testing 1 . Page 12 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court REFERENCES CITED Atwater, B.F., 1992, Geologic evidence for earthquakes during the past 2,000 years along the Copalis River, southern coastal Washington: Journal of Geophysical Research, v. 97, p. 1901 -1919. Balsillie, J.J. and Benson, G.T., 1971, Evidence for the Portland Hills fault: The Ore Bin, Oregon Dept. of Geology and Mineral Industries, v. 33, p. 109 -118. • Carver, G.A., 1992, Late Cenozoic tectonics of coastal northern California: American Association of Petroleum • Geologists -SEPM Field Trip Guidebook, May, 1992. Cornforth and Geomatrix Consultants, 1992, Seismic hazard evaluation, Bull Run dam sites near Sandy, Oregon: unpublished report to City of Portland Bureau of Water Works. Geomatrix Consultants, 1995, Seismic Design Mapping, State of Oregon: unpublished report prepared for Oregon Department of Transportation, Personal Services Contract 11688, January 1995. Goldfinger, C., Kulm, L.D., Yeats, R.S., Appelgate, B, MacKay, M.E., and Cochrane, G.R., 1996, Active strike - slip faulting and folding of the Cascadia Subduction -Zone plate boundary and forearc in central and northern Oregon: in Assessing earthquake hazards and reducing risk- in the Pacific Northwest, v. 1: U.S. Geological Survey Professional Paper 1560, P. 223 -256. Madin, I.P., 1990, Earthquake hazard geology maps of the Portland metropolitan area, Oregon: Oregon Department of Geology and Mineral Industries Open -File Report 0 -90 -2, scale 1:24,000, 22 p. Peterson, C.D., Darioenzo, M.E., Burns, S.F., and Burris, W.K., 1993, Field trip guide to Cascadia paleoseismic evidence along the northern California coast: evidence of subduction zone seismicity in the central Cascadia margin: Oregon Geology, v. 55, p. 99 -144. Unruh, J.R., Wong, I.G., Bott, J.D., Silva, W.J., and Lettis, W.R., 1994, Seismotectonic evaluation: Scoggins Dam, Tualatin Project, Northwest Oregon: unpublished report by William Lettis and Associates and Woodward Clyde Federal Services, Oakland, CA, for U. S. Bureau of Reclamation, Denver CO (in Geomatrix Consultants, 1995). Werner, K.S., Nabelek, J., Yeats, R.S., Malone, S., 1992, The Mount Angel fault: implications of seismic- reflection data and the Woodburn, Oregon, earthquake sequence of August, 1990: Oregon Geology, v. 54, p. 112 -117. Yeats, R.S., Graven, E.P., Werner, K.S., Goldfinger, C., and Popowski, T., 1996, Tectonics of the Willamette Valley, Oregon: in Assessing earthquake hazards and reducing risk in the Pacific Northwest, v. 1: U.S. Geological Survey Professional Paper 1560, P. 183 -222, 5 plates, scale 1:100,000. • • Yelin, T.S., 1992, An earthquake swarm in the north Portland Hills (Oregon): More speculations on the seismotectonics of the Portland Basin: Geological Society of America, Programs with Abstracts, v. 24, no. 5, p. 92. Youd, T.L., and Hoose, S.N., 1978, Historic ground failures in northern California triggered by earthquakes: U. S. Geological Survey Professional Paper 993, 177p. Page 13 "' Z .' r GEOPACIFIC ENGINEERING, INC, ' ,, ',, 17700 SW Upper Boones Ferry Road, Suite 100 VICINITY MAP i I, � 1' Tel (503) Oregon 2 98 -8445 Fax (503) 598 -8705 • `" } 'v. : " ., ; - :ti NORTH A 1 1 131'; lt ljl t l •1'''..' I ' f I ' _y t I _•i _ :� it isihct t TI •('„'i,I,'P4'.'11, . ,cis- L . ? . ?:'. 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' 'iN,,tr, ..:,, '-,-;'' %, - ' ', / . -, •1 ' ' .:* ---'• -_ - ' ' '''• ; 1 - I I • I'W'fi,4' , Ar;';' , 'S':. q•20'-',.' g.7 '',-,',-;',-,,.','-',., A. , : 1,,P' .., - . - i - '! ' • ..,'. .k ' ', - • - ; ' I , -,,, , - ''; . t,';'-f A ';'''''' , 6 ''' ' - , ..1' - ,_'. .'' , -)" • .4'.' r .:,, ,..., ,... ,,,, . .,,,,,.• .. . ._ . • - • , I. t , . , . .. i ..■ . n . 4_,. , _ ...„....,, : A -' •-- ,-4-. ' • ' 4" , ;•• . • • - •••• • ' . , Legend 0 20 ft 1—,..--... •i% Test Pit Designation -t$ Dynamic Cone Penetrometer 1 Date: 5/11/01 I TP-1 and Approximate Location ppcp.i Designation and Approximate Location SCALE 1"=20' Drawn by: EJO • Project: Baylor Court Job No. 01-7282 FIGURE 2 I , Tigard, Oregon • • GEOPACIFIC EF(19UNGINEERING, INC. Project No. 01 -7282 Baylor Court APPENDIX A FIELD EXPLORATIONS, SAMPLING, AND LABORATORY TESTING On May 11, 2001, five exploratory test pits were excavated on the subject property to depths of 3 to • 6.5 feet at the approximate locations shown in Figure 2. A GeoPacific Engineering Geologist evaluated and logged the borings with regard to soil type, moisture content, relative strength, groundwater content, etc. and collected representative samples for laboratory analysis. Logs of the test pits are presented in this Appendix. The test pits were excavated with an 8 -ton Mitsubishi MS070 trackhoe operated by Dan Fischer Excavating, Inc. of Banks, Oregon using a 28 -inch bucket. All excavations were backfilled immediately after completion of logging and sampling. Minimal compactive effort was applied to test pit backfill. Classification, Moisture Content, and Unit Weights Soil samples were evaluated, described, and classified in accordance with ASTM D2488 Visual - Manual Procedure, the Unified Soil Classification System, and the Oregon Department of Transportation Soil and Rock Classification Manual. All natural moisture samples were collected in plastic bags, and tested in accordance with the methods outlined in ASTM D2216. Moisture content is expressed as a percentage of the mass of water lost during oven drying to the dry weight of soil. Portable Dynamic Cone Penetrometer Tests Field tests were conducted with a Portable Dynamic Cone Penetrometer _(PDPC) to determine the strength parameters of the native soil for support of pavement. The tests were performed at the approximate locations shown on Figure 2. Table Al - PDCP -1 Field Test and Correlated CBR Height (mm) Penetration (mm) No. of Blows mm per blow Correlated CBR 1030 seating 795 235 3 78 _ 2 645 150 3 50 4 505 140 3 47 4 405 100 3 33 6 320 85 3 28 7 230 90 3 30 7 * Test started at 18 inches below existing grade Page 14 GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court Table A2 - PDCP -2 Field Test and Correlated CBR Depth Driven (mm) Penetration (mm) No. of Blows mm per blow Correlated CBR 1020 seating 903 127 3 42 4 840 63 3 21 10 755 85 3 28 7 660 95 3 32 6 585 75 3 25 8 547 38 3 13 18 517 30 3 10 22 488 29 3 10 22 460 28 3 9 25 425 35 3 12 18 352 73 6 12 18 261 91 6 15 14 211 50 3 17 • 13 * Test started at 12 inches below existing grade r Page 15 GEOPACIFIC ENGINEERING, INC. . 1 17700 SW Upper Boones Ferry Road, Suite 100 j ' '�¢ °�?Q .• � Portland, Oregon 97224 TEST PIT LOG f , 7 a ! 1 Tel: (503) 598 -8445 Fax: (503) 598 -8705 Project: Baylor Court Project No. 01 -7282 Test Pit No. TP -1 Tigard, Oregon _ N o C a) � � O II m E F- w � � a ` > N U O N Q) (n N N C N t ) a ° o � 0 3 Material Description co c E — a cn U CO I - Organic, clayey SILT (ML -OL) with rock fragments, dark brown, abundant roots, moist (Fill) 1 2.0 Very stiff, clayey SILT (ML), light brown to brown, roots, damp (Soil B- Horizon) 2- 2.0 3- 2.5 4 - - 4.0 Very stiff to hard, clayey SILT (ML), light brown, uniform, micaceous, damp (Willamette Formation) 5 - Dry below 5 feet 6--- Medium hard (R3) BASALT, gray, no vesicles (Boring Lava) 7._.- Practical refusal at 6 to 6.5 feet on hard (R4) basalt _.. 8-- Note: No significant seepage or groundwater encountered. 9 -- 10 -- 11- i -- 12 13 ( 14 15 i 16- 17- H LEGEND o Date Excavated: 5/11/01 e Gal too Logged By: PAC a B��ke de� , ,go0 5 Surface Elevation: r _ Ba Sample Bucket Sample Shelby Tube Sample Seepage Water Bearing Zone Water Level at Abandonment I - GEOPACIFIC ENGINEERING, iINC. k.r 17700 SW Upper Boones Ferry Road, Suite 100 TEST PST LOG Portland, Oregon 97224 ift " ` Tel. (503) 598 -8445 Fax (503) 598 -8705 Project: Baylor Court Project No. 01 -7282 Test Pit No. TP -2 Tigard, Oregon _ _ E N - (� C -c �E t- wc� �N 0 ° y °' �' ° _ M aterial Description TEL o.- = a o� o . p N O C a i� a � 0 Organic, clayey SILT (ML -OL), dark brown, abundant roots, moist (Topsoil) 1 - 1.5 Stiff, clayey SILT (ML) with some rock fragments, light brown to brown, some 2 3.5 roots, damp (Soil B- Horizon) 3 -- Soft (R2) to medium hard (R3) BASALT, fractured and weathered 4 __ with clayey silt seams (Weathered Boring Lava) -- Practical refusal at 3 to 4.5 feet on hard (R4) basalt 5 6 Note: No significant seepage or groundwater encountered. 7 - -- 8- 9 -- 10 I 11 -- 12- 13 i 14- 11 15 -- i 16 17 LEGEND o Date Excavated: 5/11/01 ( 5 Gal Logged By: PAC ,00 to Bucke 41 ,,000g Surface Elevation: Bag Sample Bucket Sample Shelby Tube Sample Seepage Water Bearing Zone Water Level at Abandonment '>� GEOPACIFIC ENGINEERING INC. p., # Y s 17700 SW Upper Boones Ferry Road Suite 100 TEST PIT �.ik Portland, Oregon 97224 61 kl® ' ,; `; Tel (503) 598 -8445 Fax (503) 598 -8705 f Project: Baylor Court Project No. 01 -7282 Test Pit No. TP -3 Tigard, Oregon s o o h 5 m m .N c co c , 42 s . Ma terial Description ' o- E � o z o � � p 0 P.. v) 0 U m Organic, clayey SILT (ML -OL), dark brown, abundant roots, moist (Topsoil) 1 1.0 2 - 2.0 Stiff, clayey SILT (ML), light brown to brown, some roots, damp (Soil B- Horizon) 3-- 2.5 Very stiff, clayey SILT (ML), light brown, uniform, damp (Willamette Formation) 4 - -- 5 -- Soft (R2) to medium hard (R3) BASALT, fractured and weathered, with clayey silt seams (Weathered Boring Lava) 6 - - - -- Practical refusal at 5 to 6 feet on hard (R4) basalt 7 -- Note: No significant seepage or groundwater encountered. ■ 8 9 10 - -- 11 -- r 12- 13 -- 14 - -- 15 16 -- 17 LEGEND Date Excavated: 5/11/01 10 5 Gel. Logged By: PAC 100 to Bucke � �� 1 0 7 ,0009 Surface Elevation: Bag Sample Bucket Sample Shelby Tube Sample Seepage Water Bearing Zone Water Level at Abandonment r or. GEOPACiFIC ENGINEERING, INC. s , 17700 SW Upper Boones Ferry Road, Suite 100 I t .� - . TEST ,z Portland, Oregon 97224 9 a� n ,,. -P . k Tel: (503) 598 -8445 Fax: (503) 598 -8705 i , Project: Baylor Court Project No. 01 -7282 Test Pit No. TP-4 I Tigard, Oregon N N 2 E - -c U 2 N D N S 5 C W C) o a o a. z-0 o§" Material Description co a <n D U m Organic, clayey SILT (ML -OL) with some basalt boulders, dark brown, abundant roots, moist (Topsoil) 1 -- 0.5 -- Stiff, clayey SILT (ML) with some basalt boulders, light brown to brown, some 2— 1.5 roots, damp (Soil B- Horizon) Soft (R2) BASALT, fractured and weathered, with clayey silt seams 3 _ (Weathered Boring Laval Test pit terminated at 3 feet 4 -- i Note: No seeps or groundwater encountered. 5 -- 6 7- 8 -- 9 - - -- i 10 -- 11 - i { 12 } 13 -- 14 - 15 - i 16 17 -- LEGEND Date Excavated: 5/11/01 3o 5Gal. ® Logged By: PAC 100 to Bucke lb 7 two Surface Elevation: Bag Sample Bucket Sample Shelby Tube Sample Seepage Water Bearing Zone Water Level at Abandonment d 1 GEOPACIFIC ENGINEERING, INC. i • { 4� 17700 SW Upper Boones Ferry Road, Suite 100 t. ;:_, Portland, Oregon 97224 TEST �� LOG Tel (503) 598 -8445 Fax (503) 598 -8705 Project: Baylor Court Project No. 01 -7282 Test Pit No. TP -5 Tigard, Oregon a) - 'N_ `) v O R E= I-' w c �N o o a „a) -n * 0 3 Material Description e CJ m Moderately organic, clayey SILT (ML -OL), brown, abundant roots, dry (Topsoil) 1 - 4.0 Very stiff, clayey SILT (ML), light brown to brown, some roots, dry 2 4.0 (Soil B- Horizon) 3 - -- 4.5 Hard, clayey SILT (ML), mottled light brown, gray, and orange, micaceous, dry -- 4 A (Willamette Formation) Test Pit Terminated at 4 feet 5 6 -- Note: No seeps or groundwater encountered. 7— ! -- 8 .._ 10 - -- i 11... r 12_ 13 14- 15 , 16- 17 - 1 LEGEND o 011k Date Excavated: 5/11/01 J( 5 Gal. Logged By: PAC 1 m 0o Bucke el 1,000 g Surface Elevation: Bag Sample Bucket Sample Shelby Tube Sample Seepage Water Bearing Zone Water Level at Abandonment t , GEOPACIFIC ENGINEERING, INC. Project No. 01 -7282 Baylor Court APPENDIX B CHECKLIST OF RECOMMENDED GEOTECHNICAL OBSERVATION AND TESTING Item Procedure Timing By Whom Done No. 1 Preconstruction meeting Prior to beginning Contractor, Developer, site work Civil and Geotechnical Engineers 2 Stripping, aeration, and root - picking operations During stripping Soil Technician 3 Compaction testing of During filling, tested engineered fill every 2 vertical feet Soil Technician (90% of Modified) or 500 cy 4 Compaction testing of During backfilling, trench backfill (90% of tested every 4 Soil Technician Modified) vertical feet for every 200 lineal feet 5 Footing excavation Prior to forming and Engineer or Geologist inspections rebar placement 6 Proof -roll of pavement Prior to base course subgrade (dry weather) Engineer or Geologist 7 Base course compaction Prior to paving, (95% of Modified) tested every 200 Soil Technician lineal feet 8 AC Compaction During paving, tested (91% (bottom lift) / 92% every 200 lineal feet Soil Technician (top lift) of Rice) 9 Final Geotechnical Engineer's report Completion of project Geotechnical Engineer Page 16