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Report Main Office Salem Office Bend Office F P.O.'Box 23814 4060 Hudson Ave., NE P.O. Box 7918 Tigard, Oregon 97281 Salem, OR 97301 Bend, OR 97708 Carlson Testing Inc • Phone (503) 684-3460 Phone (503) 589 -1252 FAX (503) 589 -1309 Phone (541) 330-9155 FAX (503) 684 -0954 FAX (541) 330 -9163 Special Ins • ection F - IMM - YL • - • ***REVISED*** November 11, 2004 T0405092.CTI I XI ' }• ,.�I 1 • r \ Cary of Tigard I _ 13125 SW Hall Blvd., Tigard, OR 97223 -8199 • Attn: Building Department Re: Washington Square — South Parking Garage 9585 SW Washington Square Road - Portland, OR - • Permit No.:. BUP2003 -00700 Dear Sir or Madam: This is to certify that in accordance with Section 1701 of the Uniform Building Code, Title 24, we have performed special inspection of the following item(s) per our inspection reports only. Our final letter is based upon our inspection reports and DLR Group Architecture & Planning's letter of acceptance dated October 29, 2004: Reinforced Concrete Post Tension ConcretelRebar /Stressing Installation of Cast-in-Place and Adhesive Anchors Structural Masonry • Structural Steel- Erection, includes verification of welder certifications, weld procedures and material certifications Installation of High Strength Bolts • All inspections and tests were performed and reported according to the requirements of Project Documents and, to the best of our knowledge, the work was in conformance with the approved plans and specifications, approved change orders and applicable workmanship provisions of the State Building Code and Standards, as well as the structural engineer's design changes, approvals and verbal instructions. Our reports pertain to the material tested /inspected only. Information contained herein is not to be reproduced, except in full, without prior authorization from this, office. If there are any further questions regarding this matter, please do not hesitate to contact this office. • . • Respectfully submitted, . CARLSON TESTING, INC. • Andrew M. Ewing President f:. • mbw . cc: . The Macerich Company -Rick Beason • ' • DLR Group Architecture & Planning — Todd Ferking ... . • Howard S. Wright Construction Co — Dan Clark • • • • Main Office Salem Office Bend Office P.O. Box 23814 4060 Hudson Ave., NE P.O. Box 7918 Tigard, Oregon 97281 Salem, OR. 97301 Bend, OR 97708 ._Carlson Testing, Inc. Phone (503) 684 -3460 Phone (503) 589 -1252 Phone (541) 330 -9155 FAX (503) 684 -0954 FAX (503) 589 -1309 FAX (541) 330 -9163 • Special Inspection "PARTIAL" • FINAL SUMMARY LETTER • November 1, 2004 • T0405092.CTI City of Tigard Con 13125 SW Hall Blvd., F Tigard, OR .97223 -8199. Attn: Building Department Re: Washington Square — South Parking Garage 9585 SW Washington Square Road - Portland, OR Permit No.: BUP2003 -00700 Dear Sir or Madam: • • This is to certify that in accordance with Section 1701 of the Uniform Building Code, Title 24, we, have performed special inspection of the following item(s) per our inspection reports only. Our final letter is based upon our inspection reports and DLR Group Architecture & Planning's letter of acceptance dated October 29, 2004: Reinforced Concrete Post Tension Concrete /Rebar /Stressing Installation of Cast -in -Place and Adhesive Anchors Structural Masonry Structural Steel- Erection, includes verification of welder certifications, weld procedures and material certifications Installation of High Strength Bolts Note: This is a partial summary letter and excludes concrete breaks for level 4 closure strip 2:25 line XZ to RR.1 line, moment frame beam XZ 2 to 2.5 line and closure strips 7.25 line QQ.4 to TT line. CTI concrete break register #4452: • All inspections and tests were performed and reported according to the requirements of Project Documents and, to the best of our knowled9e, the work was in conformance with the approved plans and specifications, approved change orders and applicable workmanship provisions of the State Building Code and Standards, as well as the structural engineer's design changes, approvals and verbal instructions. Our reports pertain to the material tested/inspected only. Information contained herein is not to be reproduced, except in full, without prior authorization from this office. If there are any further questions regarding this matter, please do not hesitate contact this office. Respectfully submitted, CARLSON TESTING, INC. An ew President • m bw cc: The Macerich Company — Rick Beason DLR Group. Architecture. & Planning — Todd Ferking Howard S. Wright Construction Co — Dam Clark • • r, ''8/25 11:36 1900 FROM: TO: 1234567 PAGE: , 2 ' •KW26. 2000 2: 40AM N0.4691 P. 2/27 S ADaPT Engineering, Inc. 800 Maynard Avenue South, Suite 403 Seattle, Washington 98134 • • a PT T Tel (206) 654 -7045 Fax (206) 654 -7048 August 11, 1999 ADaPT Job No. OR99 -2522 Sprint PCS ORI GINA p 4683 Chabot Drive, Suite 100 • • Pleasanton, CA 94588 Attention: Mr. Torn Hosmer Subject Geotechnical Engineering Evaluation Sprint PCS Mall ('Tigard) P029XCO53A 9585 S.W. Washington Square Road Tigard, Oregon 97008 Dear Mr. Hosmer: i Pursuant to your request, ADaPT Engineering, Inc. (ADaPT) is pleased to submit this report describing our recent geotechnical engineering evaluation for the above - referenced site. The purpose of this study was to interpret genera] surface and subsurface site conditions, from which we could evaluate the feasibility of the project and formulate design recommendations concerning site preparation, equipment pad and tower foundations, structural fill, and other considerations. Our - scope of services consisted of a surface reconnaissance, a subsurface exploration, geotechnical analyses, and report preparation. Written authorization to proceed with our study was provided via facsimile by Mr. Tom Hosmer of Sprint PCS on July 15, 1999. This report has been prepared for the exclusive use of Sprint PCS, and their agents, for specific application to this project in accordance with generally accepted geotechnical engineering practices. This report is provided f 5 / . , � H � Auction and transmittal of this report or any section of this report S o_S . .S5e p .sue 3 vithout the written permission of ADaPT is prohibited. G e.0 7p C, � 1► .. _ 08/ 1 :38 1900 FROM: TO: 1234587 PAGE: 3 KG1V126. 2000 2:40AM NO. 4691 P. 3/27 ADaPT Engineering, Inc. Sprint PCS ADaPT Job No, OR99 -2522 August 11, 1999 U Page 2 We appreciate the opportunity to be of service to you. If you have any questions, or if we can be of further- assistance to you, please contact us at (206) 654-7045. ADaPT Engineering, Inc. Respectfully submitted, . John Esteem, R.G. -- Senior Geolo ist • .v. Lew, frefti. r .._. Senior Geotechnical Engineer � PRop -.. - oc 0%1NfER G Jim Imbrie, P.E. � 14743 Senior Geotechnical Engineer Senior Reviewer OREGON 0 KVL/Jee v q� fS 2p e ��,. ��. G -30-00 • Attachments: Figure I Location Map Figure 2 Site and Exploration Plan Appendix A Boring Logs Appendix B Soil Resistivity Test Results • • • I. • • 008/25 11:36 1900 FROM: TO: 1234567 PAGE: 4 K26. 2000 2: 41 AM NO.4691 P. 4/27 • Sprint PCS Geotechnical Engineering Evaluation Mall PO29XCO53A Tigard, Oregon OR99 -2522 August 1999 • 48 /25 11:37 1900 FROM TO: 1234567 PAGE: 5 K26.2.000 2:41AM N0. 4691 P. 5/27 ADaPT Engineering, Inc. Sprint PCS ADaPT Job No. OR99 -2522 August 11, .1999 \.r Page 1 PROJECT DESCRIPTION - -- The proposed Sprint tower site is located at 9585 S.W. Washington Square Road (Washington County) in • Tigard, Oregon. The site property consists of a large retail shopping center (Washington Square) and associated parking lots. The proposed tower site is located in a landscaped area on the north side of the shopping center's north parking lot, adjacent to the parking area perimeter access road. The surface of the proposed lease area is sloped and currently covered with grass and weeds. The site can be accessed from the shopping center's northern parking lot. We understand that the site development would include the construction of a 60 -foot monopole tower and associated cellular equipment cabinets. The project site and surrounding area are shown on the attached site vicinity map (Location/To — Exploration Plan (Location/Topographic Map, Figure 1). The attached Site and Face (Figure 2) shows the approximate location of the proposed cellular tower lease area in relation to other site features, - It should be emphasized that the conclusions and recommendations contained in this report are based on our understanding of the currently proposed use of the project site, as derived from written information supplied to us by Sprint PCS. Consequently, if any changes are made to the project, we recommend that we review the changes and modify our recommendations, as appropriate, to reflect those changes. — \_ EXPLORATORY METHODS We explored surface and subsurface conditions at the project site on July 23, 1999. Our surface exploration consisted of a visual site reconnaissance. Our subsurface exploration consisted of advancing three soil test borings (B -1, B -2 and B -3) to depths of 21.5 feet, 20.5 . feet, and 3.5 feet below ground surface (bgs), respectively. The locations of the soil borings are shown on the attached Site and Exploration Plan (Figure 2). Due to the slope of the proposed tower site, soil borings were Iocated at the base of the slope, approximately 20 feet south of the proposed tower location. The specific location and depth of the exploration performed was selected in relation to the proposed site • features, under the constraints of budget and site access. The location of the borings and other features shown on Figure .2 were obtained by hand taping from existing site features. As such, the exploration location shown on Figure 2 should be considered accurate to the degree implied by the measuring methods used. Boring Methods Soil Borings B -1, B -2 and B -3 were advanced on July 23, 1999 using a thick hollow -stem auger drill rig. The drill rig was operated by an independent company working under subcontract to . 08/25 11:37 1900 FROM: TO: 1234567 PAGE: 6 KG 26.2000 2:41AM NO. 4691 P. 6/27 ADaPT Engineering, Inc. Sprint PCS • ADaPT Job No. OR99 -2522 August 11, 1999 ` Page 2 ADaPT. A field geologist from our firm continuously observed the boring, obtained representative soil samples, and logged the subsurface conditions. After the boring was completed, the boreholes were _ backfilled with a mixture of soil cuttings and bentonite chips. - During drilling, soil samples were obtained at 5 -foot depth intervals using the Standard Penetration Test V (SPT) procedure (ASTM: D 1586). This test and sampling method consists of driving a standard 2 -inch outside diameter (OD) split - barrel sampler a distance of 18 inches into the soil with a 140 -pound hammer, • free- falling a distance of 30 inches. The number of blows required to drive the sampler through each of the three, 6-inch intervals is noted. The total number of blows struck during the final 12 inches of penetration is considered the Standard Penetration Resistance, or "blow count". If 50 or' more blows are struck within one 6 -inch interval, the driving is ceased and the blow count is recorded as 50 blows for the actual number of inches of penetration. The resulting Standard Penetration Resistance values provide a measure of the relative density of granular soils or the relative consistency of cohesive soils. The boring logs appended to this report describe the various types of soils encountered in the borings, based primarily on visual interpretations made in the field. The logs also indicate the approximate depth of the contacts between different soil types, although these contacts may be gradational or undulating. Where a change in soil type occurred between sampling intervals, we have inferred the depth of contact. In addition, the log indicates the depth of any groundwater observed in the boring, the Standard Penetration Resistance at each sample location, and any laboratory tests performed on the soil samples. Soil Resistivity Test In accordance with your request, field soil resistivity testing was also conducted at the above referenced site. The field soil resistivity test was performed in accordance with ASTM method 0-57 (JFF Standard 81) using a Wenner electrode configuration with four electrodes spaced about the tower center at 5, 10, 15, and 20 foot spacing. The results of the field soil resistivity testing are presented in Appendix B. • Laboratory Testing ADaPT has retained the soil samples collected from the test borings during this investigation. We • contacted Mr. Tom Roamer of Sprint regarding the soils at the site. In our opinion, considering the nature and density of the soils encountered at the site, laboratory testing would not be required. • 'I — 08/25 11:38 1900 FROM: TO: 1234567 PAGE: 7 KOM26. 2000 2:42AM NO. 4691 P. 7/27 ADaPT Engineering, Inc. Sprint PCS ADaPT Job No. .0R994522 August 11, 1999 Page 3 SITE CONDITIONS _ The following sections describe ow observations, measurements, and interpretations concerning surface, soil, groundwater, and seismic conditions at the project site. Surface Conditions The proposed. Sprint tower site is located at 9585. S.W. Washington Square Road (Washington County) in Tigard, Oregon. The site property consists of a large retail shopping center (Washington Square) and associated parking lots. The proposed tower site is located in a landscaped area on the north side of the shopping center's north parking lot, adjacent to the parking area perimeter access mad. The surface of the proposed lease area is sloped and currently covered with grass and weeds. The site can be accessed from the shopping center's northern parking lot. We understand that the site development would include the construction of a 60 -foot monopole tower and associated cellular equipment cabinets. The project site • and surrounding area are shown on the attached site vicinity map (Location/Topographic Map, Figure 1). The attached Site and Exploration Plan (Figure 2) shows the approximate location of the proposed cellular tower lease area in relation to other site features. Subsurface Conditions • On July 23, 1999, three exploratory soil borings, B -1, B-2 and B -3, were drilled to depths of 21.5, 20.5 and 3.5 feet bgs, respectively. The locations of the soil borings are shown on Figure 2. Surficial conditions encountered at the boring locations at the base of the slope:consisted of approximately 2 to 4 inches of gravel, underlain by silt. Soils encountered generally consisted of dry, very stiff silt with minor amounts of sand or gravel. A change in lithology from SILT to bard mudstone was noted at approximately 20 feet bgs in both B -1 and B-2. While no groundwater was encountered in any of the three soil borings, groundwater conditions can vary seasonally with changes in precipitation, or with changes in site utilization and other,factors. The following parameters are based on available correlation between soil type and texture, as well as density and consistency inferred from Standard Penetration Test values: • 08/25 11:38 1900 FROM: TO: 1234567 PAGE: 8 K 26.2000 2:42AM NO. 4691 P. 8/27 • ADaPT Engineering, Inc. Sprint PCS ADaPT Job No. OR99.2522 August 11, 1999 • Page 4 TABLE 1 Depth Interval Soil Type Range of air Vane C'(pd) 0° '' (pct) (Feet) 0 - 0.3 Gravel N/A N/A N/A N/A 0.3 — 21 Silt 32 — 39 1,000 25° 125 21+ Mudstone 50+ 2,000 35° 145 Seismic Conditions According to the Seismic Zone Map of the United States contained in Figure 16-2 of the 1997 Uniform Building Code (LJBC), the project site lies within Seismic Risk Zone 3. Based on our subsurface exploration, we interpret the site conditions to correspond to a seismic Soil Profile type SD, for Stiff Soil Profile, as defined by Table 16-J of the 1997 Uniform Building Code, based on the observed range of Standard Penetration Test (SPT) blow counts. The shallow soil conditions were assumed to be representative for site conditions beyond the depths explored. CONCLUSIONS AND RECOMMENDATIONS Current development plans call for construction of a 60 -foot monopole tower and associated cellular equipment cabinets. Based on the subsurface conditions encountered in our boring, the proposed tower could be supported on either a mat or drilled pier foundation. Design criteria .for compressive, uplift and lateral support of mat and drilled pier foundations are presented below. Our specific recommendations concerning site preparation, equipment. steel flamed platform foundations, tower foundations, access driveway and structural fill are presented in the following report sections. Site Preparation Site preparation will involve removal of vegetative cover, topsoil, and organic matter, grading, and preparing subgrades. The following comments and recommendations apply to site preparation: Clearing and Grubbing: Some grade changes will be required to achieve proposed site grades. At this location, site preparation will consist of removal of vegetation, topsoil, and organic matter, grading, followed by foundation preparation for the monopole cellular tower and equipment cabinet platform Depending on the actual location of the tower, selective tree removal and grubbing of root balls may be necessary. Backfill materials, when; required, should be placed and compacted according to the • recommendations presented in the Structural Fill section of this report • • 08/25 11:39 1800 FROM: TO: 1234567 PAGE: 9 I26 .2000 2:43AM NO. 4691 P. 9/27 ADaPT Engineering, Inc. • Sprint PCS ADaPT Job No..OR99.2522 August 11, 1999 Page 5 Wet Conditions: Because of the high fines content of the existing near surface site soil, these soils are both moisture- sensitive and prone to disturbance when wet. The contractor should minimize traffic above the prepared subgrade areas to minimize disturbance and softening which would require removal of the unstable soils. During wet conditions, the use of a working surface of quarry spans or clean sand and gravel may be. required to protect the subgrade, especially from vehicular traffic. -- Frozen Subgrades: If earthwork takes place during freezing conditions, we recommend that all exposed subgrades be allowed to thaw and be recompacted prior to placing subsequent lifts of structural fill. Equipment Cabinet Retaining Wall Foundation It is our understanding that the foundation for the proposed equipment platform for the cellular cabinets will consist of concrete piers. We anticipate that the vertical load imposed by the equipment will be • relatively light. Design criteria for the small diameter piers are attached. We recommend that the retaining wall foundation be designed as spread footings. The following recommendations and comments are provided for purposes of piers and footing design and construction: : The proposed equipment retaining wall footings may be supported by the existing site soils encountered at depths below 1.5 feet at the locations of borings B -1 through B -3, after they have been compacted in place resulting in a firm and unyielding subgrade condition, or upon structural fill placed above similarly prepared soils. We anticipate the subsoil encountered at the proposed foundation grade will likely consist of stiff to hard sandy silt. Depending on the time of yearr that construction proceeds, it may be possible to compact those soils in place. The near surface sandy silt is fine grained. It will be difficult to achieve a specified.compaction should moisture contents above the optimal moisture condition be encountered at the time of construction. Some over-excavation may be necessary if excessively soft or wet subgrade conditions were to be encountered at the foundation design grade levels. We recommend the over - excavation extend no deeper than 2 - feet below the retaining wall footing "bearing — elevation. A layer of geotextile may be required to separate the structural fill soils from the underlying subgrade materials. Footings should never be cast atop soft, loose, organic, or frozen soils; nor atop subgrades covered by standing water. A representative from ADaPT should be retained to observe the condition of footing subgrades before concrete is poured to verify that they have been adequately prepared. Footing Dimensions: We recommend that the retaining wall footing be designed as a spread footing and • be constructed to have a minimum width of 18- inches. For frost protection, the footings should penetrate ` at least 18 inches below the lowest adjacent exterior grades. Footings may be supported on structural fill placed on prepared soil subgrade. The horizontal limits of the fill pad below the building or cabinet • 08/25 11:39 1900 FROM: TO: 1234567 PAGE: 10 KJ26.2000 2:43AM NO. 4691 P. 10/27 • ADaPT Engineering, Inc. Sprint PCs ADaPT .lob No. OR99 -2522 August 11, 1999 • Page 6 foundation may be established by extending.a line outward from the base of the thickened slab at an angle • of 1 Horizontal: !Vertical (1H: 1V) down to the upper surface of the bearing horizon. Bearing Pressure: At the location of boring B -1, the near surface soil should be shipped, excavated to a depth of at least 18- inches below the lowest adjacent grade. The soils at that elevation should be compacted in place if the moisture contea allows, resulting in a firm and unyielding subgrade condition. Alternatively, the retaining wall footings could be supported above a maximum thickness of two feet of • _ compacted fill, underlain by a layer of geotextile (filter fabric), if required. A maximum allowable soil bearing pressure of 2,700 pounds per - square -foot can be used for static footing. loads. This bearing pressure can be increased by one-third to accommodate transient wind or seismic loads. An allowable - . base friction coefficient of 0.35 and an allowable passive earth pressure of 300 pounds per cubic foot (pct), expressed as an equivalent fluid unit weight, may be used for that portion of the foundation embedded more than 1 foot below finished exterior subgrade elevation. $ettlemente• We estimate that total post - construction settlements of properly .designed footings bearing on properly prepared subgrades could approach 1- inch, with differential settlements approaching one -half of the total. Lateral Design Earth Pressures The lateral forces which act against the retaining wall are a function of the soil type, drainage, and slope • • configuration behind the wall. Conventional retaining walls may be designed to resist a lateral earth pressure expressed as an equivalent fluid density, equal to 35 pounds per cubic foot. This pressure would apply for the conditions of a horizontal ground surface behind the wall. For 2 Horizontal : 1 Vertical sloping ground surface, such as on the uphill side of the wall, the lateral earth pressure should be increased by 50 per cent. The backfill behind the wall should be free - draining and contain less than 5 per cent fines. This drainage media should extend at least 18- inches behind the wall, and should be capped at the ground surface by one foot compacted thickness of the native silt soils. We recommend any wall be provided with a footing drain. The footing should be designed in accordance with recommendations outlined in the previous report section. Equipment Cabinet Foundations It is our understanding that the steel frame platform supporting the proposed cellular equipment cabinets will be supported on shallow drilled pier foundations consisting of four poured in place concrete 12 -inch diameter caissons. We understand that the vertical compressive load will be in the order of 7,000 to • 1 I r 08/25 11:40 1900 FROM: TO: 1234587 PAGE: 11 • K01 2000 2:.44AM NO. 4691 P. 11/27 — ADePT Engineering, Inc. Sprint PCS ADaPT Job No. OR99 -2522 August 11, 1999 Page 7 10,000 pounds. The following recommendations and comments are provided for purposes of shallow drilled pier design and construction: Vertical compressive loads could be resisted by end bearing on shallow drilled pier foundations extended through the surficial topsoil into the very stiff to bard deposits encountered at the site. We recommend that the drilled piers penetrate at least 8 feet below the ground surface at the proposed equipment frame location. For design purposes, we recommend that a maximum allowable end bearing pressure of 5,000 pounds per square foot be utilized for the shallow drilled piers for static loads. The bearing pressure can be increased by one -third to accommodate transient winds or seismic loads. The allowable end . bearing pressure includes a safety factor of 1.5 or more. For frictional resistance of the drilled piers, acting both downward and in uplift, we recommend using an allowable skin friction value of 700 pounds per square foot applied at the interface of the drilled pier and native silt soil. The uppermost 2 feet of soil below the ground surface should be neglected for frictional resistance. The allowable skin friction value includes a safety factor of 1.5. Lateral forces may be resisted by passive pressure developed against the sides of drilled piers. The passive pressure maybe applied over 2 the pier diameters in width by 8 pier diameters in depth, neglecting the uppermost 2 feet of embedment below the ground surface. The allowable passive pressure, expressed as an equivalent fluid density equal to 300 pounds per cubic foot, may be assumed for design- _ The passive pressure approach is conservative by neglecting the redistribution of vertical stresses and shear forces that develop near the bottom of the pier and contribute to resisting lateral loads. We have incorporated a safety factor of at least 1.5, which is commonly applied to transient or seismic loading - - conditions. Access Driveway The proposed lease tower area can be accessed via the existing parldng lot perimeter road. Therefore, construction of an access driveway is not required. Tower Mat Foundations In order to provide adequate resistance to horizontal, axial and overturning loads, a reinforced concrete mat footing could be used for tower foundation support. The following recommendations and comments are provided for purposes of mat footing design and construction: • • Subgrade Conditions: Footing subgrades should consist of firm, unyielding native soils. The mat : foundation should never be cast atop soft, loose, organic, or frozen soils; nor atop subgrades covered by 08/25 11:40 1900 FROM: TO: 1234567 PAGE: 12 1 J 4 26 . 2000 2:45AM NO. 4691 P. 12/27 - ADaPT Engineering, Inc. Sprint PCS -- ADaPT Job No. OR99 -2522 August 11, 1999 • Page 8 standing water. A representative from ADaPT should be retained to observe the condition of mat subgrade soils before concrete is poured to verify that they have been adequately 1 epared. Embedment : We recommend that the mat foundation be embedded at least 8 -feet below the existing ground surface bearing on the very stiff to hard sandy silt underlying the site, as disclosed by Soil Borings B-1. through B-3. After excavation to the design footing grade, the surface of the bearing horizon should be cleaned of material loosened by excavation and compacted in place resulting in a firm and unyielding subgrade condition prior to placement of rebar and concrete. Bearing Press: A maximum allowable soil bearing pressure of 5,000 pounds per square foot can be used for - static loads to minimize foundation settlement. For shallow footings, the amount of settlements that will take place is directly related to the size of the footing fora given bearing pressure. Depending on the allowable settlement that can be tolerated, higher bearing pressure may be recommended. We can be contacted to provide recommendations for higher bearing pressures, if desired, for this site. This bearing pressure incorporates a factor of safety of 1.5 or more and can be increased by one -third to . accommodate transient wind or seismic loads. We expect that uplift loads will be resisted by the dead load of the mat foundation, as well as the weight of soils covering the mat. Native soils used to cover the mat and compacted to a minimum of 90 percent of the modified Proctor maximum dry density could be assumed to have a unit density of 120 pcf. Lateral Resistance: Lateral loads on the foundation caused by seismic or transient loading conditions may be resisted by a combination of passive soil pressure against the side of the foundation and shear friction resistance along the base. An allowable base friction coefficient of 0.35 for the very dense fine sand- concrete interface and an allowable passive earth pressure of 300 pounds per - cubic -foot (pcf), expressed as an equivalent: fluid unit weight, may be applied against that portion of the foundation embedded at least 2 feet in native soils. We recommend that the passive earth pressure contribution of the upper 2 -feet of embedment be fully discounted Seam: We estimate that total post-construction settlements of properly designed mat foundation bearing on properly prepared subgrades could approach 1 inch, with differential settlements approaching one - half of the total. • Tower Drilled Pier Foundadons As an alternative to a mat foundation, the tower could be supported on a drilled pier foundation. The following recommendations and comments are provided for purposes of drilled pier design and construction: • 08/25 11:41 1900 FROM: TO: 1234587 PAGE: 13 K 26. 2000 2:45AM NO. 4691 P. ,13/21 ADaPT Engineering, Inc. Sprint PCS ADaPT Job No. OR99 -2522 August 11, 1999 Page 9 Compressive Capacities: We recommend that the drilled pier penetrate at least 10 -feet below the grotmd • • surface at the location of boring B -1. For vertical compressive soil bearing capacity, we recommend using the unit end bearing capacity presented in Table 2 below. The allowable end bearing capacity, presented in Table 2, includes a safety factor of 1.5 or more. We anticipate that adequate pier embedment for end bearing, uplift and lateral resistance can generally be obtained within the limits of ow exploration of 20 -feet. Table 2 Allowable End Bearing Capacity Depth (feet) • Allowable kiarfieg' Clip y r • Limiting Point Resistance (tel) 10 -20 5.0 DB 20 TSF Notes: D = the embedment depth (in feet) into the beating layer. B = pier diameter (feet). • Frictional Capacities: For frictional resistance of the drilled piers, acting both downward and in uplift, we recommend using the allowable skin friction value listed in Table 3. We recommend that frictional resistance be neglected in the uppermost 2 feet below the ground surface. The allowable skin friction value presented includes a safety factor of 1.5. • Table 3 • • Allowable Skin Friction Capacities Depth (feet) Allowable Skin Friction (tsf) 0 -2 - 0.0 2 -20 0.55 Lateral Capacities: For design against lateral forces acting against the drilled pier, two methods are typically used. The parameter used to select the appropriate design method is the length to pier stiffness ratio UT, where L is the pier length in inches, and T is the relative stiffness factor. The relative stiffness factor (T) should be computed by: • ' 08/25 J l 1900 FROM: TO: 1234567 PAGE: 14 ` AJ 26.2000 2:45AM N0.4691 P. 14/27 ADaPT Engineering, Inc. • Sprint PCS ADaPT Job No. OR99 -2522 August 11, 1999 Page 10 os T =(EI) where E = modulus of elasticity (psi) I = moment of inertia (in n = constant of horizontal subgrade reaction (pci) The factors E and I are governed by the internal material strength characteristics of the pier. A representative value of iH, for the soil types encountered at this site is presented below in Table 5. Piers with a UT ratio of less than 2 may be assumed to be relatively rigid and acting as a pole. The passive .. pressure approach may be used for this condition. For piers with a LIT ratio greater than 2, the modulus of subgrade reaction method is typically used. Both of these methods are discussed below: Passiye. Pressure Method: The passive pressure approach is conservative by neglecting the redistribution of vertical stresses and shear forces that develop near the bottom of the pier and contribute to resisting _ lateral loads. We recommend using the allowable passive earth pressure (expressed as equivalent fluid unit weights) listed in Table 4. Table 4 Allowable Passive Pressures . _ Depth (feet) Allowable Passive Pressure (pcf) mss 02 0 • 2 -20 300 The allowable passive earth pressure presented in Table 4 may be assumed to be acting over an area measuring 2 pier diameters in width by 8 pier diameters in depth, neglecting the uppermost 2 feet of embedment below the ground surface. According to the NAV'PAC Design Manual 7.02 (1986), a lateral deflection equal to about 0.01 times the pier length would be required to 'mobilize the allowable passive pressure presented above. Higher deflections would mobilize higher passive pressures. When developing, the allowable passive pressure listed in Table 4, we have incorporated a safety factor of at least 1.5, which is commonly applied to transient or seismic loading conditions. Modulus of Subgrtde Reaction Method: Using this method, the pier is designed to resist lateral loads based on acceptable lateral deflection limits. For granular soils, the coefficient of horizontal subgradc • reaction (k is considered to be directly proportional to the depth along the pier. The formula to determine k is k = n where xis the depth below the ground surface in inches. We recommend using the value for the constant of horizontal subgrade reaction (rib) for thevanious soil types presented in Table 5 below. • 08/25 11:42 1800 FROM: TO: 1234587 PAGE: 15 K26. 2000 2:46AM NO. 4691 P. 15/27 ADaPT Engineering, Inc. Sprint PCS ADaPT Job No. OR99 -2522 August 11, 1999 Page. 11 Table 5 • Constant of Horizontal Subgrade Reaction (na) Depth (feet) na (Pct) 0 -2 0 2 -20 30 • Construction Ccrosideraticmn: Even though generally favorable conditions were encountered, the foundation - drilling contractor should be prepared to case the excavation to prevent caving and raveling of the pier shaft sidewall. The actual depth to the mudstone is not Down at the tower location. Very difficult drilling should be anticipated if the pier needs to penetrate the basal mudstone unit Groundwater was not encountered in the test borings. Should unanticipated heavy groundwater inflow be encountered during drilling it may be necessary to pump the accumulated groundwater prior to pier concrete placement Alternatively, the use of bentonite slurry could be utilized to stabilize the drilled pier - excavation. The foundation - drilling contractor should be prepared to case the . excavation to prevent caving and raveling of the pier shaft sidewalls. The drilling contractor should be prepared to clean out the bottom of the pier excavation if loose soil is observed or suspected, with or without the presence of slurry or groundwater. As a minimum, we - recommend that the drilling contractor have a cleanout bucket on site to remove loose soils and/or mud from the bottom of the pier. If groundwater is present and abundant within the pier hole, we recommend that the foundation concrete be tremied from the bottom of the hole to displace the water and minimize the risk of contaminating the concrete mix. The Drilled Shaft Manual published by the Federal Highway Administration recommends that concrete be placed by tremie methods if more than 3 inches of water has accumulated in the excavation. Structural Fill The following comments, recommendations, and conclusions regarding structural fill are provided for design and construction purposes: Materials: Structural fill includes any fill materials placed under footings, pavements, driveways, and — other such structures. Typical materials used for structural fill include: clean, well - graded sand and gravel (pit -run); clean sand; crushed rock; controlled- density fill (CDF); lean -mix concrete; and various _ soil mixtures of silt, sand, and gravel. Recycled concrete, asphalt, and glass, derived from pulverized parent materials may also be used as structural fill, 08/25 11:42 1900 FROM: TO: 1234567 PAGE: 16 K 'jI26. 2:46AM NO. 4691 P. 16/27 . ADaPT Engineering, Inc. Sprint PCS ADaPT Job No. OR99 -2522 August 11, 1999 . Page 12 Placernentand Compaction: Generally, CDF, and lean -mix concrete do not require special placement and • compaction procedures. In contrast, pit-run, sand, crushed rock, soil mixtures, and recycled Materials . should be placed in horizontal lifts not exceeding 8 inches in loose thickness, and each lift should be • thoroughly compacted with a mechanical compactor. Using the modified Proctor maximum dry density • (ASTM: D -1557) as a standard, we recommend that structural fill used for various on -site applications be compacted to the following minimum densities: Minimum Compaction Slab/Footing subgrade 90 percent Gravel drive subgrade (upper 1 foot) 95 percent Gravel drive subgrade (below 1 foot) 90 percent Subgrades and Testing: Regardless of location or material, all structural fill should be placed over firm, unyielding 'subgrade soils. We recommend that a representative from ADaPT be retained to observe the condition of subgrade soils before fill placement begins, and to perform a series of in - place density tests during soil fill placement. In this way, the adequacy of soil compaction efforts may be evaluated as • • earthwork progresses. Fill Co= Soils used for structural fill should not contain individual particles greater than about 6 inches in diameter and should be free of organics, debris, and other deleterious materials. Given these prerequisites, the suitability of soils used for structural fill depends primarily on.the grain -size distribution and moisture content of the soils when they are placed. When the "fines" content (that soil fraction passing the U.S. No. 200 Sieve) increases, soils become more sensitive to small changes in moisture content Soils containing more than about -5 percent fines (by weight) cannot be consistently compacted to a firm, unyielding condition when the moisture content is more than about 2 percentage points above optimum. The existing near - surface silt soils at this site contain an elevated fines content and should be considered highly moisture sensitive. The use of "clean" soil is necessary for fill placement dining wet - weather site work, or if the in - situ moisture content of the sandy silt soils is too high to allow adequate compaction. Clean soils are defined as granular soils that have a fines content of less than 5 percent (by weight) based on the soil fraction passing the U.S. No.3 /4-inch Sieve. • • CLOSURE • The conclusions and recommendations presented in this report are based, in part, on the explorations that we performed for this study. If variations hi subsurface conditions are discovered during earthwork, we may need to .modify this report. The future performance and integrity of the tower foundations will depend largely on proper initial site preparation, drainage, and construction procedures. Monitoring by • 08/25 11:43 1900 FROM: TO:. 1234587 PAGE: 17 K 111 426. 2000 2:47AM NO. 4691 P. 17/27 ADaPT Engineering, Inc., Sprint PCS ADaPT Job No. OR99.2522 August 11, 1999 Page 13 experienced geoteebaical personnel should be considered an integral part of the construction process. We are available to provide. geotechnical engineering services during the earthwork and foundation construction phases of the project. If variations in the subgrade conditions are observed at that time, we • would be able to provide additional geotechnical recommendations, thus minimizing delays as the project develops. We are also available to review preliminary plans and specifications before construction begins, and to provide geotechnical inspection and testing services during construction. • • • 08/25 11:43 1900 FROM: TO: 1234567 PAGE: 18 26. 2000 2:47AM NO.4691—P. 18/27— 1 6- l' ':' ▪ '' ' "Y. _Iii; FT , � • J � � ' :r . • Y• . I r 6 JI .. r :" " : '-'-'; ' . ' L I 1 10 , ... .5 . : . , ,,t, - _)--_.?.. I � " '1 .7-=•,,t,,.. ' r , _ 9 j .. .• , k "4 ar r , 71 • ic y l�' •4, . •/� - A , . • � _ � � �.r�! • �" �� ; • ,, 1 ., '' r' .=97.1 0 0 R. ipa i • 0 • r 1 .' • V.P,: . I \, * ''' .'` 1 .- ::4 ) ' '. Z ‘;-,.:- • .<,4 4 - ..•1' :'.. 5 - 1: )) 44; 01; .'ii 1, eff ... • • O. 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FIGURE 1 - Location /Topographic Map 800 Maynard Avenue S., Suite 403 Location : Sprint PCS P029XCO53A - MALL Seattle, Washington 98134 9585 SW Woshington Sguore Rood 9 Tlgord, Oregon 97223 client : Sprint PCS Ph : 206.654.7045 Fax : 206.654.7048 Oats : 8/11/99 Job 4 : S -OR -99 -2522 08/25 11:44 1900 FROM: TO: 1234567 PAGE: 19 KEM26. 2040 2:49AM NO. 4691 P. 1 • LI ‘ PROPOSED UTILITY EASEMENT - I I • PROPOSED LEASE AREA I . i I I I. r I I I P P' , APPROXIMATE BORING LOCATION NOT TO SCALE ADaPT Engineering, Inc. FIGURE 2 - Site Plan 800 Maynard Avenue S. Suite 403 Location :Sprint PCS P029XCO53A — MALL Seattle, Washington 98134 9585 SW Washington Square Rood Tigard, Oregon 97223 Mont : Sprint PCS Ph : 206.654.7045 Fox : 206.654.7048 Date : 6/t1/99 Job 4.: S -OR - 99 - 2522 t " 08/25 11:45 1900 FROM: TO: 1234587 PAGE: 20 KQUM26. 2000 2:49AM NO. 4691 P. 20/27 ADaPT Engineering, Inc. _- APPENDIX A BORING LOGS • 08/25 11:45 1900 FROM: TO: 1234587 PAGE: 21 K014426. 2000 2:49AM NO. 4691_P. 21/27_ 'N L ADEPT Engineering, Inc B O R G OG 17700 8W Upper Booms Reny Road Sums 100 PORTLAND, OREGON 97224 TEL 503.598.8445 FAX:503.598.8705 T PROJECT : 9 SW Washington Square Road Job Number OR-99 -2622 Boring No.: E-1 Tigard, Oregon 97223 Sprint PCS •'ds,__••`•: NIA W"' Golfo ibacIA vaposek. Mow I p O•I"d: N. TERM Ne■ 0.S NI • 11 bIilI 11 1/ 1b Unsurfaced, 2-4 inches gravel basecourse - . . -5- Gray and brown mottled, dry; very stiff, SILT 1s ' I si 1s 17 - 1 0- Dark gray with light and dark brown specks, s2 16 • moist, very stiff, SILT with minor gravel 15 19 - Dark gray and brown, slightly moist, very stiff, . sandy SILT 64 7 n V . -- . - B rown and gray mottled, dry, very stiff, SILT > 1 1 -20- grading to gray, dry, hard mudstone - 511 ' — Boring terminated at 20.5 feet - - - No groundwater encountered _ . -25- - - • . :3o- - . . .EGEND - U Z muneaed.aooam amour WM aDM, % amain* • - 1 1 ram mrerrur iii +1..dAvYdTtsisoWW o.wounae.r,�a .1.., w:�,do...so r. ma., Page: E X 'W MD rihmaorg I of 1 1 Drilling Start Dale : 7/2.39 tiling Campli1Ton Dine : 7/13199 Legged 4: JE — • e - 08/25 11:45 1900 FROM: TO: 1234567 PAGE: 22 Ked26. 2000 2:50AM NO. 4691 P. 22/27 ADaPT Engineering, Inc. BOR ING LOG B o o m PORTLAND. OREGON 87224 . -- -- TEL: 508.598.8445 FAX: S09 988.8706 • PROJECT Mall Job Number : OR-99 -2522 Boring No.: B.2 9585 SW Washington Square Road PO20XCO53A Tigard, Oregon 97223 Sprint PCS ~^, o M A: in AS-guar DESIGN 'x"10 — 11 il 11 fi ol li Unsurfaced, 2-4 Inches gravel basecourse - -5- No SPT _ -10- No SPT - — X , - -,,.._ 5 . Dark gray and brown, dry to slightly moist, very stiff, sandy SILT 1 31 7 9 SA • Gray, dry, hard MUDSTONE -20- 'T sz sue • — Boring terminated at 20.5 feet , - ___. No groundwater encountered _ . . -25- - . • -30- - • - - • ,EGEND _ _ S ThmnRepePompM u � am Sift ' o,tSwam PardadOszabir Ei Tips if MOW Tidee Used I liumb rim Ammo 12+-1 e X .ra 11t 1 of 1 Pulling Stan Date : .7129/99 DrUMp Completion Dam: 7x23/99 .� Sy : JJI: '08/25'11:46 1900 FROM: TO: 1234567 PAGE: 23 • • -. • �K 26. 2001 2:50AM� NO. 4691 P. 23/27 = - BORING LOG ADaPT Engineering, Inc. 7700 sw UK* Boons Pony Road Sub 100 MILANO, OREGON 97224 TEL 503.598.8446 FAX:509.598.8705 — P Mail Job Number : OR -99 -2522 BoringNoo : B$ 9585 SW Washington Square Road PCS XCO53A Tigard, Oregon 97223 Sprint Iard. Rims : NM wN c.. . Pik • - 6uh i a�: NA asrre aa.ara.i Not AS�UILTOESiGN ��° N Unsurfaced, 2-4 inches gravel basecourse Light brown, and gray mottled, dry, hard, SILT 1 & ° . say • Boring terminated at 3.5 feet — . • 6 No groundwater encountered — • • . : II — . 2 • M III : •,, • . ■ __. _ II . : - - . __...__ ■ • • • EGEND • ,-1... eend ha. Z pkspe6mma ea Mx xWANDi* %/ aft sm. awe "It"' Dat �r1o >1+'•a4^1•MTw7u . d I X/ �..roapaoa.nd Z wearao MIMMIN arao.y .: /� = ae aem.aOft 1 of 1 - tog Stan barn : 7123189 Cana Completion Dale : 7/23189 LOpged By : A 08/.5 11:46 1900 FROM TO: 1234567 PAGE: 24 I( .2000 2:50AM NO. 4691 P. 24/27 ADaPT Engineering, Inc. APPENDIX B SOIL RESISTIVITY TEST RESULTS 1 . 08/25; 11 :46 1900 FROM: TO: 1234567 PAGE: 25 K26. 2000 2:51AM NO..4691 P. 25/27 ADaPT Engineering, Inc. • • • Resistivity Survey Results Project Name: Mall (P029XCO53) ADaPT Job No.: OR -99 -2522 — Project Address: 9585 S.W. Washington Square. Road Tigard, Oregon 97008 Date: 8/29/99 Time: 2:30 PM Weather Sunny, 88 °F Distance Between Electrodes Ohmic Meter Readings Calculated Resistance (feet) (ohms) (ohm -cm) 5 3.1 2,968 10 1.6 3,064 15 1.3 3,734 - 20 1.7 6,511 The . resistivity survey was completed using the Wenner Four- Electrode Method in general accordance • — ` with ASTM method G - 57 - 95a (IEEE Standard 81), using a Nilsson Model 400 Soil Resistance Meter. •