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MST vv ``ivaY 7 /21/12 414-7Lumt - LANPACIFIC Civil Engineering LonoscoDe Architecture Lond Use Plon.RECEIVEP NOV 3 2014 APPENDIX Eo CITY OF TIGARD ° BUILDING DIVISION GEOTECHNICAL REPORT GT Geo technical&Environmental Consultants l�{\ 9725 SW Beaverton-Hillsdale Hwy,Ste 140 Portland,Oregon 97005-3364 PHONE 503-641-3478 FAX 503-644-8034 October 20, 2004 4134 GEOTECHNICAL RPT LanPacific, Inc. 1001 SE Water Avenue, Suite 360 Portland, OR 97214 Attention: Erik Esparza, PE DRidi F SUBJECT: Geotechnical Investigation Arlington Heights Subdivision Tigard, Oregon At your request, GRI has completed a geotechnical investigation for the above-referenced project. The general location of the project is shown on the Vicinity Map, Figure 1. The proposed development extends northward from SW Beef Bend Road, 300 ft past SW Autumnview Street between SW 122nd Avenue and SW Summerview Street. The purpose of the investigation is to evaluate subsurface materials and conditions at the site and develop criteria for design and construction of the subdivision. The investigation consisted of subsurface explorations, laboratory testing, and engineering studies and analyses. This report describes the work accomplished and provides our conclusions and recommendations for site development. PROJECT DESCRIPTION We understand the proposed 7-acre development will include construction of about 700 ft of street improvements, related utilities, and 22 house lots. The configuration of the development is shown on the Site Plan, Figure 2. Based on discussions with you, we understand the maximum height of cuts and fills required to construct the proposed subdivision will be less than about 7 and 14 ft, respectively. You have also indicated that the depth of the utilities will be a nominal 10 ft. SITE DESCRIPTION Topography Our observations at the site and review of topographic information you provided indicate the site slopes to the southeast and south from about elevation 430 ft at the northwest corner of lot 1 to about 245 ft at lot 22. The northern half of the site is typically flatter than about 3H to 4H:1 V, and the slopes become less steep in the southern half of the site. A prominent drainage feature is present on the east side of the site, and wetlands have been defined at various locations along the alignment. The embankment fill for the unpaved portion of SW Autumnview Street is partially completed and was apparently The side of placed when the east and west segments of the road were constructed. slopes g the embankment fill have a slope of about 2H:1 V. Geology The site is mantled with Uplands Silt, which is underlain by Columbia River Basalt at relatively shallow depths. The Upland Hills Silt is commonly yellow-brown, sandy and clayey silt and contains occasional scattered pebbles. The underlying basalt is typically weathered on the surface and increases in hardness with increasing depth. The basalt weathers to a reddish-brown, clayey silt or silty clay that frequently exhibits the relict structure of the parent rock. Corestones of hard, unweathered basalt are also common to the weathering profile. The contact between the Upland Hills Silt and the underlying weathered basalt is frequently associated with the occurrence of landslides. Groundwater The regional groundwater is commonly found deep within the underlying basalt. However, a shallow perched aquifer is also known to exist in the Bull Mountain area. The surface aquifer is commonly found above the basalt and produces seeps and springs on the hillsides and in manmade cuts. This shallow groundwater regime fluctuates with seasonal rainfall and will approach the ground surface during the wet,winter months. Surface Conditions On August 30, 2004,a geologist from GRI conducted a ground-level geologic reconnaissance of the site to characterize surficial conditions. The reconnaissance focused on soils exposed at the ground surface, indications of slope instability, seepage, and other pertinent site characteristics. The general locations of features observed during the reconnaissance and discussed in the following paragraphs are shown on Figure 2. ' The location of a wetland or spring that extends from the northeast corner of the property south to SW Beef Bend Road is shown on Figure 2. GRI observed surface water flow in significant portions of the wetland during our investigation. Portions of the spring are underground between lots 14 and 17, and adjacent to lot 18, where surface water was not observed but the ground was soft and damp. A second spring flows from Lot 11 to SW Beef Bend Road along the west side of the site. South of the SW Autumnview alignment, the wetland delineation shows the spring located east of the eastern property boundary of the site. We anticipate the flow in the springs will increase during the rainy season,and the groundwater level could approach the ground surface adjacent to the mapped springs and in other areas of the site. Our observations indicate the proposed alignment of SW Autumnview Street and the area to the north have been graded to some degree in conjunction with the construction of adjacent developments and associated utilities. It appears that fill was placed in the road alignment to extend utilities across the site. A stockpile of uncompacted silt fill or strippings is present north of the roadway alignment, see Figure 2. The stockpiled material primarily consists of brown silt with a trace of fine-grained sand. Indications of recent ground movement or deep-seated slope instability were not observed during the • reconnaissance. Although not directly obvious,areas of soil creep are likely occurring over portions of the site where slopes are steeper than 20 to 25°. Soil creep is the slow, gradual downslope movement of surface soils due to gravity. 2 SUBSURFACE CONDITIONS General Subsurface materials and conditions at the site were investigated between August 23 and September 10, 2004, with nine test pits, designated TP-1 through TP-9, and three borings, designated B-1 through B-3. The approximate locations of the test pits and borings are shown on Figure 2. The test pits ranged from about 4 to 12.5 ft deep; the borings were advanced to depths of 14.5 to 30 ft. The field exploration and laboratory testing programs completed for this investigation are further described in Appendix A. Logs of the borings and test pits are shown on Figures 1A through 4A. The terms used to describe the materials encountered in the explorations are defined on Tables 1 A and 2A. Soils For the purpose of discussion, the materials disclosed by the subsurface investigation have been grouped into the following four categories: 1. Gravel FILL 2. Silt FILL 3. SILT 4. BASALT 1. Gravel FILL. Fine to coarse gravel fill was encountered at the ground surface in borings B-1 and B-2 and extended to depths of 5 and 9 ft, respectively. The gravel fill is brown and contains percentages of silt ranging from some to silty. The relative density of the gravel is medium dense, based on N-values in the range of 12 to 29 blows/ft. The natural moisture content of the soil ranges from about 13 to 20%. 2. Silt FILL. Brown,gravelly silt fill was encountered at the ground surface in test pits TP-8 and TP-9. The fill extended to depths of 3 and 6.5 ft, respectively. The relative consistency of the silt fill is stiff based on observations and resistance to excavation. The silt was too stiff to measure the undrained shear strength using a Torvane shear device. 3.SILT. Brown to gray silt with rust mottling was encountered beneath the fill and at the ground surface in the other explorations. The silt contains a trace to some fine-grained sand and clay. Torvane shear strength values of 0.30 to 0.75 tsf and N-values in the range of 11 to 25 blows/ft indicate the relative consistency of the silt is medium stiff to stiff. The natural moisture content of the silt ranges from about 9 to 34%. The silt is typically very dry in the upper 2 ft,and the moisture content increases with depth. Scattered cobble-size fragments of relatively fresh, gray, vesicular basalt are present in the silt below depths of 8 to 10 ft in test pits TP-1 through TP-6. 4. BASALT. Very soft (RH-1) to medium hard (RH-2) basalt was encountered in borings B-1 through B-3, and in test pits TP-1, TP-3, TP-4, TP-6. The trackhoe encountered practical refusal at the surface of the basalt. The degree of weathering and hardness of the basalt was highly variable between explorations. The basalt was reddish-brown to dark gray. It is our experience with other nearby projects that the hardness and density of the basalt increase with increasing depth. 3 Groundwater Moderate groundwater seepage was observed in several of the test pits. Heavy groundwater seepage was noted at a depth of 1 ft in test pit TP-7. An observation standpipe was installed in boring B-1 to monitor the groundwater level up through the time of construction. Static groundwater levels in the standpipe and the depth to groundwater seepage in the test pits are summarized in the table below. SUMMARY OF GROUNDWATER LEVELS Location Depth to Groundwater (8/23/2004) (9/20/2004) B-1 -- dry(>14) TP-1 9 -- TP-2 9.5 -- TP-4 7.5 -- TP-7 1 -- TP-9 3 -- Based on our understanding of local geologic conditions and our observations at the site, we anticipate that perched groundwater conditions may occur within the Upland Hill Silt at or near the ground surface during wetter periods of the year. At depth, groundwater may perch above the weathered surface of the underlying basalt. Obvious springs are present on the site and are shown on Figure 2. CONCLUSIONS AND RECOMMENDATIONS The planned development site is located on the southeast side of Bull Mountain. The area is characterized 1 V. We understand the maximum height of cuts and fills will be 7 and 14 bygentle slopes as steepas 3 H. g Pe ft, respectively. The subsurface explorations made for this investigation indicate the site is primarily mantled with firm silt soils that are underlain by soft(RH-1)to hard (RH-3)basalt. Based on the results of this investigation and our experience with similar developments, it is our opinion that the site is suitable for the proposed development. In our opinion, the most important geotechnical considerations associated wih the planned development are the fine-grained moisture-sensitive soils, the of seeps and springs, and the shallow depth to basalt bedrock. Relatively hard basalt presence relatively P was encountered at depths of 8 to 12 ft in our subsurface explorations. Utility excavations that extend below these depths may require rock excavation techniques. Based on explorations completed in the proposed SW Autumnview Street alignment and on lots 19 siltygravel, and gravellysilt and through 22,the existing fill soils in these areas consist of relativelydense, in our opinion,are suitable for support of proposed roads and building foundations. However,the quality of the fill should be further evaluated during construction, and it should be anticipated that areas of unsuitable fill that require overexcavation may be identified. Site Preparation The ground surface within areas of mass grading should be stripped of vegetation, surface organics, and loose surface soils. We estimate that stripping will generally be necessary to a depth of about 6 to a in the northern, in. within the limits of the open field area. Deeper grubbing will be necessary 4 wooded portion of the site to remove stumps and roots larger than about 1 in. in diameter. Strippings can be used in landscaped areas or removed from the site. Following stripping and prior to filling, the subgrade should be evaluated by a qualified geotechnical engineer for the presence of soft areas. If present, soft areas should be overexcavated and replaced with compacted structural fill as described below. Some overexcavation should be anticipated due to the presence of fill and signs of grading north of the SW Autumnview Street alignment. During and following stripping and excavation, the contractor must use care to protect the subgrade from disturbance by construction traffic. The fine-grained silty soils at the site are sensitive to moisture content when exposed to repetitive construction traffic. During wet conditions, the soils are easily disturbed, rutted, and weakened by construction activities. Also during wet conditions, it should be anticipated that haul roads constructed of imported granular fill will be required to provide access and to protect subgrade areas from damage due to construction traffic. An 18- to 24-in. thickness of fragmental rock is usually necessary to support heavy truck traffic. The performance of haul roads can usually be improved by placing a geotextile over the fine-grained subgrade soils prior to placing the rock. The thickness of granular fill can be reduced by treating the silt subgrade soils with an admixture such as lime or cement. Cuts and Fills We understand the maximum height of cuts and fills required to establish site grades will be about 7 and 14 ft, respectively. In our opinion, on-site or imported, organic-free soils approved by the geotechnical engineer may be used to construct structural fills. However, the on-site, fine-grained soils are sensitive to moisture content and can be placed and adequately compacted only during the dry summer months. As excavations near the final subgrade elevation, it will be necessary for the contractor to exercise care and good working procedures to avoid disturbance and softening of the exposed subgrade materials. All fill placed for streets, sidewalks, and residential lots should be installed as compacted structural fill. Approved organic-free, fine-grained soils used to construct structural fills should be placed in 9-in.- thick -in:thick (loose) lifts and compacted to at least 95% of the maximum dry density, as determined by ASTM D 698, using an adequately sized segmented-pad or sheepsfoot roller. Vibratory smooth-drum or plate compactors are usually not satisfactory for compaction of the silt soils. Rock fragments larger than about 8 in. should be removed from the fill. In landscape areas or areas not sensitive to settlement, fill and strippings should be compacted to about 90% of the maximum dry density, as determined by ASTM D 698. We recommend the moisture content of structural fill material be controlled to within 3% of the optimum moisture content at the time of compaction. It has been our experience that it is difficult to adequately compact wetter soils. If the fill is compacted at moisture contents wetter than recommended, pronounced pumping and rutting of the material will occur under the wheels or treads of construction equipment. The pumping and rutting are indications that the fill material is too wet, relatively weak and compressible,and may require treatment with lime or cement or replacement with granular structural fill. The natural moisture content of the in situ soil across the site was commonly about 20 to 30% at the time of our investigation. In this regard, it should be anticipated that some aeration and drying of the borrow material will be necessary to achieve the required compaction. 5 If construction continues during wet-weather conditions, structural fills can be constructed with imported, granular material, such as sand, sandy gravel, or fragmental rock of up to about 6-in. size and having less than 5% passing the No. 200 sieve (washed analysis). It may also be feasible to use lime or cement treatment to permit use of the on-site soil to construct structural fill during limited periods of wet weather. It has been our experience that lime or cement treatment can also be used to treat soft subgrade areas, and make subgrade areas less vulnerable to disturbance and softening by heavy construction traffic, particularly during wet ground conditions. Permanent cut and fill slopes should be constructed at 2H:1V or flatter. Structural fill should be placed and compacted a minimum of 2 ft beyond the final slope configuration and then trimmed back to final grade. Where fills are to be placed on existing slopes steeper than about 5H:1V, the area to be filled should be terraced or benched to provide a relatively level surface for fill placement. Typical benching requirements are illustrated on Figure 3. We anticipate benching will be required for fills on the north half of the site. Depending on the conditions observed during construction, it may also be appropriate to include drainage improvements, such as the drain and drainage blanket shown on Figure 4. In this regard, we anticipate that subdrainage will be required in the bottom of swales, drainages, springs, and low-lying areas of wet surficial soils prior to placing structural fill. The subdrainage should be sloped to drain and should discharge away from slopes or future development. Seeps or springs that emerge on cut slopes may require additional drainage provisions depending on the actual conditions observed during construction. These provisions could include drainage ditches, drainage blankets, and subdrains, possibly placed in utility trenches to intercept and remove water. It should be anticipated that the depth of weathering in the underlying basalt is variable, and layers of relatively unweathered basalt and/or boulders may be encountered in cuts. We anticipate the materials disclosed by the test pits can be excavated by moderate to large dozers and hydraulic excavators equipped with rock teeth. Based on our observations at the site, we anticipate there is some risk of encountering zones of harder rock that could require rock excavation methods. It should be anticipated that the newly exposed soils on cuts and fills will be susceptible to erosion and should be revegetated as soon as practical after construction. If it is anticipated that an adequate vegetation cover may not be established before the onset of the wet winter season, a heavy mulch cover or commercially available mulching mesh may be required to minimize erosion. In addition, surface drainage should be directed away from slopes. Utilities In our opinion,there are three major considerations in the design and construction of new utilities. 1) Provide stable excavation side slopes or support for trench sidewalls to minimize loss of ground. 2) Provide a safe working environment during construction. 3) Minimize post-construction settlement of the utility and the ground surface. 6 The method of excavation and the design of trench support are the responsibility of the contractor and subject to applicable local, state,and federal safety regulation, including the current OSHA excavation and trench safety standards. The means, methods, and sequencing of construction operations and site safety are also the responsibility of the contractor. The information provided below is for the use of our client and should not be interpreted to mean that we are assuming responsibility for the contractor's actions or site safety. According to the most recent OSHA regulations,the majority of the fine-grained soils and weathered basalt materials encountered in the test pits and borings may be classified as Type C. In our opinion, trenches less than 4 ft deep may be cut vertically and left unsupported during the normal construction sequence, i.e., assuming trenches are excavated and backfilled in the shortest possible sequence,and excavations are not allowed to remain open longer than 8 hrs. Excavations that are greater than 4 ft deep should be laterally supported or alternatively provided with stable side slopes of 1 H:1 V or flatter. In our opinion, adequate lateral support may be provided by common methods, such as the use of a trench shield or hydraulic shoring systems. We anticipate that minimal groundwater will be encountered in the utility trench excavations if work is • performed during the drier months of the year. Perched water may be encountered in the surface silty soils following periods of sustained heavy precipitation. In those areas where groundwater inflow occurs, it may be necessary to overexcavate the trench bottom and place clean, fragmental rock up to about 4-in. size to stabilize the trench bottom. We anticipate that groundwater inflow, if encountered, can be controlled by pumping from sumps. We anticipate that the majority of the trench excavations will be in silt soils that may contain cobbles and large basalt boulders. If relatively hard rock is encountered within the deeper utility excavations, boulders that protrude above the planned bottom of trench grade should be removed and replaced with compacted granular fill. Based on the results of our subsurface explorations for this site and other nearby sites, the upper weathered surface of the basalt can generally be excavated using a large trackhoe equipped with a rock excavation bucket. However, relatively hard (RH-3 to RH-4), moderately to slightly weathered basalt may be encountered that will require rock excavation methods. Utility trenches within building,pavement,and sidewalk areas should be backfilled with granular structural fill, such as sand, sand and gravel, or fragmental rock of up to 2-in. maximum size with less than 5% passing the No. 200 sieve (washed analysis). Granular backfill should be placed in lifts and compacted to 95% of the maximum dry density as determined by ASTM D 698. Compaction by jetting or flooding should not be permitted. ' Slope Stability Indications of active, large-scale or deep-seated slope movement were not observed during our reconnaissance. Although not directly obvious,areas of soil creep are likely occurring over portions of the site where slopes are steeper than about 20 to 25°. Soil creep is the slow, downslope movement of surficial soils due to gravitational forces acting on steep slopes and is generally limited to.a depth of 2 to 5 ft below the ground surface. A grading plan is not available at this time. We will evaluate the stability of proposed slope configurations when the grading plan is available. Foundation Support The residential lots were not staked in the field at the time of the geotechnical investigation. However, we anticipate the generally medium stiff to stiff, naturally occurring silt soils at the site, as well as structural fill installed in accordance with our recommendations, will provide suitable support for residential-type structures. Conventional spread foundations established in the medium stiff to stiff silt soils or structural fill can be designed to impose a maximum real bearing value of up to 1,500 psf. This value applies to continuous wall-type footings and pedestal or column footings having a minimum dimension of 16 in. and established at a minimum depth of 18 in. below lowest adjacent exterior grade and 12 in. below lowest adjacent interior grade. In addition, footings established on slopes should be set back a minimum horizontal distance of 10 ft from the face of the slope. If construction is performed during the wet season, it may be desirable to install a 3-in. thickness of 3i4- in.-minus crushed rock toP rovide a firm working surface and prevent disturbance and softening of the subgrade soil. We anticipate the settlement of spread foundations constructed in conformance with the above recommendations will be less than 1/2 in. Due to the presence of springs and the potential for shallow, perched groundwater conditions during wet weather, adequate drainage should be provided for all embedded walls and slab-on-grade floors. In general, drainage can be provided by placing a layer of clean, free-draining, granular material adjacent to embedded walls and beneath floor slabs. Commonly available, clean, free-draining granular material consists of 3/4—to 1i4-in. or 11/2—to 3/4-in. crushed rock with less than 2% passing the No. 200 sieve. The granular material is typically drained by perforated pipes. Typical subdrainage construction is shown on Figure 5. In areas where floor coverings will be provided or moisture-sensitive materials are stored, it may be appropriate to also install a vapor-retarding membrane. The vapor-retarding membrane should be installed in accordance with the manufacturer's recommendations. Typical details of a vapor-retarding system that has worked successfully in similar applications are shown on Figure 5. Embedded Walls Design lateral earth pressures for embedded walls depend on the type of construction, i.e.,the ability of the wall to yield. Possible conditions are a wall that is laterally supported at its base and top and therefore is unable to yield and a conventional cantilevered wall that yields by tilting about its base. Non-yielding walls should be designed using a lateral earth pressure based on an equivalent fluid having a unit weight of 45 pcf. Walls that are allowed to yield by tilting about their base should be designed using a lateral earth pressure based on an equivalent fluid having a unit weight of 35 pcf. These design earth pressures assume - the backfill behind the wall and ground in front of the wall are horizontal. These design earth pressures also assume that the embedded walls are fully drained. Therefore, we recommend the installation of a permanent drainage system behind all embedded walls,as shown on Figure 5. Overcompaction of the backfill behind walls should be avoided. In this regard, we recommend compacting the backfill to about 93%of the maximum dry density(ASTM D 698). Heavy compactors and 8 large pieces of construction equipment should not operate within 5 ft of any embedded wall to avoid the buildup of excessive lateral pressures. Compaction close to the walls should be accomplished using hand- operated vibratory plate compactors. Lateral forces that may be induced on the wall due to surcharge loads, such as adjacent building foundations, floor loads, landscaping,or parked vehicles, may be estimated using the guidelines shown on Figure 6. Pavement Design We anticipate that paved areas within the completed development will be primarily subjected to light automobile traffic and occasional heavier truck traffic (e.g., garbage trucks, moving vans, etc.). It has been our experience with similar developments that the most severe traffic conditions are associated with heavy dump trucks and concrete trucks during development of residential lots. Traffic estimates for the roadways of the proposed development are presently unknown. Based on our experience, we anticipate that for the firm soils at this site, a pavement section consisting of 4 in. of asphaltic concrete (AC) placed over 12 in. of crushed rock base would perform well under construction traffic. However, a thicker section of crushed rock base will be necessary if the work is completed during wet conditions. It may also be feasible to use a thinner pavement section in some areas that are not subjected to heavy construction traffic. However, a thinner section could require more maintenance and repair. We can review the above-recommended sections when traffic estimates become available. To provide quality materials and construction practices, we recommend the pavement work conform to the "Standard Specifications for Highway Construction," used by the Oregon Department of Transportation. In those areas where the pavement will be placed over a granular work pad, it will probably only be necessary to remove the contaminated surface material, i.e., the upper few inches, and replace this with the crushed rock base course prior to paving. However, prior to any grading or paving, the granular work pad or subgrade soils should be proof rolled with a fully loaded 10 yd3 dump truck. v r xcavated and backfilled with compacted Any soft and/or wet areas should be o structural fill.e e Properly installed drainage is an essential aspect of roadway design. All paved areas should be provided with positive drainage to remove surface water and water within the base course. This will be particularly important in cut sections or at low points within the paved areas, such as at catch basins. Effective methods to prevent saturation of the base course materials include roadside drainage ditches in communication with and below the base course, providing weep holes in the sidewalls of catch basins, installing subdrains in conjunction with utility excavations, and constructing separate trench drain systems. Construction Observation Services Considering the amount of mass excavation required for the development, the somewhat variable subsurface conditions, presence groundwater theof seeps, it should be anticipated that conditions will be encountered during earthwork that, from a practical standpoint, can only be resolved by field decisions and directives. It should be anticipated by the owner that frequent site visits by the geotechnical engineer will be required during the site work to evaluate the contractor's work, identify potential areas of concern, and provide the owner and engineer with advice and recommendations to 9 address these concerns and to observe compliance with the design concepts, specifications, and recommendations. We would be pleased to provide these services for you. LIMITATIONS This report has been prepared to aid in the evaluation of this site and to assist the engineer in the design of this project. The scope is limited to the specific project and location described herein, and our description of the project represents our understanding of the significant aspects of the project relevant to the design and construction of the proposed home sites and associated streets and utilities. In the event that any changes in the design and location of the project, as outlined in this report, are planned, we should be given the opportunity to review the changes and to modify or reaffirm the conclusions and recommendations of this report in writing. The conclusions and recommendations submitted in this report are based on the data obtained from the test pits and borings completed at the locations indicated on Figure 2 and from other sources of information discussed in this report. In the performance of subsurface investigations, specific information is obtained at specific locations at specific times. However, it is acknowledged that variations in soil and groundwater conditions may exist between exploration locations. This report does not reflect any variations that may occur between these explorations. The nature and extent of variation may not become evident until construction. If, during construction, subsurface conditions different from those encountered in the explorations are observed or encountered, we should be advised at once so that we can observe and review these conditions and reconsider our recommendations where necessary. Submitted for GRI, David D. Driscoll, PE Matthew S. Shanahan, PE Principal Staff Engineer F 10 it, 1-- ' r t' _ r, L i • `111 � } , Ips} i _� , -.--.- - - - i / ,I _;r ../.S ---- — f I ,+. — _ — y 7 ----.' ....,,,, 1,:i.,___.----i- ......., ,„........„ _ _ i _- < 1z z . / .. _ .... •rte J 1• >,� ._—_ 1 -•— _ /i - DELORME 3-0 TOPOQUADS,OREGON WEST BEAVERTON,OREG.(4bc)1999 North A 0 1 2 MILES I . G RD LANPACIFIC INC. ARLINGTON HEIGHTS SUBDIVISION VICINITY MAP OCT.2004 I0B NO. 4134 FIG. 1 1 CUT SLOPE EXISTING GROUND SURFACE PROPOSED ROADWAY OR BUILDING PAD 2(MIN.) FILL SLOPE 8 FT(MIN.)->-1 2(MIN.) % .1i 4 FT(MAX.) BENCHES (TYPJ 5 FT(MIN.) > < LANPACIFIC INC. CJ R ARUNGTON HEIGHTS SUBDIVISION TYPICAL DETAIL FOR FILLING ON SLOPES OCT.2004 JOB NO.4134 FIG.3 CLEAN FRAGMENTAL ROCK,WELL GRADED,FREE DRAINING, NOMINAL MAXIMUM SIZE OF 8 IN. oa • . G� p oO 18 IN.(MIN.) • . Q O GEOTEXTILE 0O I t / STRIPPED GROUND 4-IN.-DIAMETER PVC DRAIN SURFACE 04.••; I LINE,PERFORATIONS DOWN • :%"•• II bLi GEOTEXTILE ENVELOPE 3/4-TO 11-1N. - ;%•. %'� DRAIN ROCK 61N. c 2 F GEOTEXTILE FOR SUBGRADE PROTECTION MAY NOT BE REQUIRED DEPENDING ON SITE CONDITIONS. DRAINAGE REQUIREMENTS WILL BE DEVELOPED BY OWNER'S REPRESENTATIVE/ENGINEER BASED ON ACTUAL FIELD CONDITIONS. LANPACIFIC INC. t. :R ARUNGTON HEIGHTS SUBDIVISION TYPICAL WORKING BLANKET AND DRAINAGE DETAIL OCT.2004 JOB NO.4134 FIG.4 • < X=mH > { I �_ STRIP LOAD,q t LINE LOAD,Q1 a I I I I I I A "�"" :�-�,�.�- 072 Z=nH 11111. PM ig For m S 0.4: NW H 11 °h = Q1 0.2n27 H ikr H (0.16+n I Form>0.4: MI ah= ° (fi-SINf COS 2a) Tr ah ah = Qt 1.28m'n / °h H (m'+n'1' (g in radians) LINE LOAD PARALLEL TO WALL STRIP LOAD PARALLEL TO WALL < X=mH > POINT LOAD,Qp A n / Z=nH PIM For m S 0.4: A-Ilk- 1 lair-lir A' _ Qv 0.28n' H Mr ah HT (0.16+n2)' Vir For m>0.4: ° ah = --1- 1.77m'n1 h H (m +n')- Ilk a'h=a h COS'(1.1 B) NOTES: O l ah 1. THESE GUIDELINES APPLY TO RIGID WALLS WITH POISSON'S Ilik ,.711 11 O RATIO ASSUMED TO BE 0.5 FOR BACKFILL MATERIALS. sr_ / 2. LATERAL PRESSURES FROM ANY COMBINATION OF ABOVE LOADS MAY BE DETERMINED BY THE PRINCIPLE OF SUPERPOSITION. ah X=mH > DISTRIBUTION OF HORIZONTAL PRESSURES VERTICAL POINT LOAD GRH LANPAARLINGTON IFIL INC. ARLINGHEIGHTS SUBDIVISION SURCHARGE-INDUCED LATERAL PRESSURE OCT.2004 JOB NO.4134 FIG.6 • APPENDIX A FIELD EXPLORATIONS AND LABORATORY TESTING FIELD EXPLORATIONS General Subsurface materials and conditions on the site were investigated between August 23 and September 10, 2004, with nine test pits, designated TP-1 through TP-9, and three borings, designated B-1 through B-3. The approximate locations of the test pits and borings are shown on the Site Plan, Figure 2. All field explorations were observed by a geotechnical engineer provided by our firm, who maintained a detailed log of the materials disclosed during the course of the work. The following subsections provide a detailed description of the field and laboratory programs completed for this project. Test Pits The test pits were excavated with a Kobelco SK-60 trackhoe equipped with a 2-ft-wide toothed bucket. The trackhoe was provided and operated by Greg Vandehey Soil Sampling of Forest Grove, Oregon. The test pits ranged in depth from 4 to 12.5 ft. Representative soil samples were obtained from the sidewalls of the excavations to a depth of about 5 ft and from the bucket of the trackhoe for depths below about 5 ft. Relatively undisturbed samples of the fine-grained soils were obtained by pushing 3-in.-O.D. Shelby tubes into the undisturbed soil a maximum distance of 24 in. using the bucket of the trackhoe. All of the samples were carefully examined in the field and returned to our laboratory for further examination and testing. Detailed logs of the test pits are provided on Figures 1A and 2A. Each log presents a descriptive summary of the various types of materials encountered in the excavation and notes the depth at which the materials and/or characteristics of the materials change. To the right of the descriptive summary, sample type and depth along with natural moisture content and Torvane shear strength values are presented. The terms used to describe the materials encountered in the test pits are defined in Tables 1A and 2A. Borings The borings were drilled with mud-rotary techniques using a truck-mounted drill rig provided and operated by Subsurface Technologies of Banks, Oregon. The borings were advanced to depths of 14.5 to 30 ft. Disturbed and undisturbed samples were typically obtained from the borings at 2.5-ft intervals in the upper 15 ft and at 5-ft intervals below this depth. Disturbed samples were obtained using a standard split-spoon sampler. At the time of sampling, the Standard Penetration Test was conducted. This test consists of driving a standard split-spoon sampler into the soil a distance of 18 in. using a 140-lb hammer dropped 30 in. The number of blows required to drive the sampler the last 12 in. is known as the standard penetration resistance, or N-value. The N-values provide a measure of the relative density of granular soils, such as sand,and the relative consistency, or stiffness, of cohesive soils, such as silt. The soil samples obtained in the split-spoon sampler were carefully examined in the field, and representative portions were saved in airtight jars for further examination and physical testing in our laboratory. A-1 Relatively undisturbed 3.0-in.-0.D. Shelby tube samples were obtained by pushing the tubes into undisturbed soil using the hydraulic rams on the drill rig. The samples were returned to our laboratory for further examination and physical testing. The logs of borings B-1 through B-3 are provided on Figures 3A through 5A. Each log provides a descriptive summary of the various types of materials encountered in the explorations and notes the depths where the materials and characteristics of the materials change. The boring logs show the depths and types of samples taken, along with natural moisture contents, and standard penetration resistance. The terms used to describe the materials encountered in the borings are defined in Tables 1A and 2A. LABORATORY TESTING General All samples obtained from the test pits and borings were returned to our laboratory where the physical characteristics of the samples were noted and the field classifications were modified where necessary. The laboratory testing program included determinations of natural moisture content, Torvane shear strength, dry unit weight, and consolidation characteristics. The following paragraphs describe the testing program in more detail. Natural Moisture Content The natural moisture content of the silty soils was determined in conformance with ASTM D 2216. The results are summarized on Figures 1A through 5A. Torvane Shear Strength The approximate undrained shear strength of soils exposed in the sidewalls of the test pits and relatively undisturbed soil samples obtained from the borings was determined using a Torvane shear device. The Torvane is a hand-held apparatus with vanes that are inserted into the soil. The torque required to fail the soil in shear around the vanes is measured using a calibrated spring. The results of the Torvane shear strength tests are shown on Figure 1A through 5A. Dry Unit Weight The dry unit weight of several relatively undisturbed samples was determined in the laboratory in accordance with ASTM D 2937 by cutting a cylindrical specimen of soil from a Shelby tube sample. The dimensions of the specimen were carefully measured, the volume calculated, and the specimen was weighed. After oven drying, the specimen was reweighed, and the water content was calculated. The dry unit weight was then computed. The dry unit weights are summarized below. SUMMARY OF DRY UNIT WEIGHT DETERMINATIONS Natural Moisture Dry Unit Test Pit Sample Depth,ft Content,% Weight,pcf Soil Type B-1 S-3 13 29 95 SILT B-3 S-4 11 29 97 SILT TP-3 5-3 6 24 94 SILT TP-5 5-1 2.5 19 93 SILT TP-6 5-2 3.5 22 94 SILT A-2 One-Dimensional Consolidation A one-dimensional consolidation test was performed in conformance with ASTM D 2435 on a relatively undisturbed Shelby tube sample from boring B-3. The test provides data on the compressibility of underlying fine-grained soils, necessary for settlement studies. The test results are summarized on Figure 6A in the form of a curve showing percent strain versus applied effective stress. The initial and final dry unit weight and moisture content of the sample are also shown on the figure. • A-3 • Table lA GUIDELINES FOR CLASSIFICATION OF SOIL Description of Relative Density for Granular Soil Standard Penetration Resistance Relative Density (N-values)blows per foot very loose 0-4 loose 4-10 medium dense 10-30 dense 30-50 very dense over 50 Description of Consistency for Fine-Grained(Cohesive)Soils Standard Penetration Torvane Resistance(N-values) Undrained Shear Consistency blows per foot Strength,tsf very soft 2 less than 0.125 soft 2-4 0.125-0.25 medium stiff 4-8 0.25-0.50 stiff 8- 15 0.50-1.0 very stiff 15-30 1.0-2.0 hard over 30 over 2.0 Sandy silt materials which exhibit general properties of granular soils are given relative density description. Grain-Size Classification Modifier for Subclassification Boulders Percentage of 12-36 in. Other Material Adjective In Total Sample Cobbles 3-12 in. clean 0-2 Gravel trace 2-10 1/4-3/4 in. (fine) 3/4-3 in. (coarse) some 10-30 Sand sandy,silty, 30-50 No. 200-No.40 sieve(fine) clayey,etc. No.40-No. 10 sieve(medium) No. 10-No.4 sieve(coarse) Silt/Clay-pass No. 200 sieve • Table 2A GUIDELINES FOR CLASSIFICATION OF ROCK Relation of RQD and Rock Quality RQD (Rock Quality Designation), % (Description of Rock Quality) 0-25 Very poor 25-50 Poor 50-75 Fair 75-90 Good 90-100 Excellent Descriptive Terminology for Joint Spacing Spacing of Joints Descriptive Term < 2 in. Very Close 2 in.-1 ft Close 1 ft-3 ft Moderately Close 3ft-10 ft Wide > 10 ft Very Wide Scale of Rock Hardness(After Panama Canal Company, 1959) RH-1 Soft Slightly harder than hard overburden soil, rock-like structure,but crumbles or breaks easily by hand RH-1 Medium Soft Cannot be crumbled between fingers,but can be easily picked with light blows of the geology hammer. RH-2 Medium Hard Can be picked with moderate blows of geology hammer. Can be cut with knife. RH-3 Hard Cannot be picked with geology hammer,but can be chipped with moderate blows of the hammer. RH-4 Very Hard Chips can be broken off only with heavy blows of the geology hammer. Terms Used to Describe the Degree of Weathering Descriptive Term Defining Characteristics Fresh Rock is unstained. May be fractured,but discontinuities are not stained. Slight Rock is unstained. Discontinuities show some staining on their surfaces, but discoloration does not penetrate rock mass. Moderate Discontinuity surfaces are stained. Discoloration may extend into rock along discontinuity surfaces. High Individual rock fragments are thoroughly stained and can be crushed with pressure hammer. Discontinuity surfaces are thoroughly stained and may be crumbly. Severe Rock appears to consist of gravel-sized fragments in a"soil" matrix. Individual fragments are thoroughly discolored and can be broken with fingers. Elev. 3*Ni) TP-1 Elev.414ft(i) o_ :ilium stiff to stiff,brown,sandy SILT;day, Stiff to very stiff,brown,sandy SILT;12-in.-thick n.-thick heavily rooted zone at the ground • 1_ heavily rooted zone at the ground surface Mace 2— OS-1 Ow=15% w=9% c=0.50tsf 3— -mottled gray and rust below 4 f Owl 25% c 4 mottled tan and rust,trace day below 4 f O S-2 a w=30% c=0.70tsf 8 5- 6— -brown,some fine-grained sand below 6.5 ft 0 S-3 f—bel brown,some fine-grained sand and clayw=27% 7 ow 7 ft O S•3 -green-gray,contains scattered cobbles O 5_4 scattered cobbles below 7.5 ft w=20% below 7.5 ft w=30% c=0.70 tsf 8— actical refusal on basalt at 8 ft(8123104) 1.5-ft boulder at 8.5 ft 3derate groundwater seepage at 7.5 ft 9 O S-4 Practical refusal on basalt at 9 ft(8123104) Moderate groundwater seepage at bottom of test pit TP-S Elev. 330ft(t) 0 Stiff to very stiff,brown,sandy SILT;6-in.-thick 1 heavily rooted zone at the ground surface 2 S-1 Ow=19% 3 c=1.0 tsf Y4=93 pd 4 mottled tan,black,and rust below 4 ft 0 S-2 .EGEND w=21% 5 medium stiff,brown,some fine-grained sand 0 = GRABSAMPLE c below 5 ft 0 = 34N.-ODSHEU3YTUBE SAMPLE 16 w = NAT1lRAl.MOISTIktE CONTENT - 7 0 S-3 c = TORVANE SHEAR STRENGTH w=29% Y4 = DRY UMT WEIGHT 8 GROUND SURFACE ELEVATIONS FROM SITE PLAN,FIGURE 2. 9 10 trace fine-grained sand and scattered O S_4 cobbles below 10 ft w 4 31% R� 11 1`D —some clay at 12 ft 12 0 S-5 TEST PIT LOGS Bottom of test pit 12 ft(8/23!04) w=31% Groundwater not encountered OCT.2004 108 NO. 4134 FIG. IA TP-8 Elev. 254 ft(t) 0 • FILL: Stiff,brown SILT;some sand,trace • — gravel,scattered cobbles 6-in.-thick heavily 1 rooted zone at the ground surface 2 OS-1 0 /edium stiff,gray mottled brown to brown w'15% 3 mottled gray SILT;some fine-grained sand, scattered fine roots 4^ O S-2 Bottom of test pit 4 ft(8123104) w=25% Groundwater not encountered c=0.40 t EGEND 0 = GRAB SAMPLE Q = 3aN.OD SHELBY TUBE SAMPLE w = NATURAL MOISTURE CONTENT c = TORVANE SHEAR STRENGTH Yd = DRY UNT WEIGHT ;ROUND SURFACE ELEVATIONS FROM SITE PLAN,FIGURE 2. ERB TEST PIT LOGS OCT 2fJ04 10B NO. 4134 FIG.2A _ STD PENETRATION RESISTANCE g CLASSIFICATION OF MATERIAL (1400 vvE GHT.304W ) i g A. MOBLOWSISTURE PER FOOT CONIFM,% c., SURFACE ELEVATION 381 ft (t) o c°3 1 0 50 100 ':lto'F FILL Medium dense,brown GRAVEL;fine to coarse,some _ ! fine-grained sand and sift • -- •••_.:;• ,..s* ,!•• i• :•6• edium stiff to stiff,brown silt with scattered gravel, Si I • • - 29--- • ;ws,« grass,and roots at 5 ft _ Stiff,brown SILT;trace fine-grained sand and day S-2 I .J2 — -- . • $.3 1.7.7.- .-74— _413s- 10 s-a I , Ayr 4, ++++ Medium soft(RH-1),reddish-brown BASALT;severely weathered t2 5 S.5 i - -`r ,5 ++++\--hard(RH-3)below 13.5 ft - ! 15 14.5 (8125/2004) t • -H --; • 20 . : i . l 25 { `; • ' 1 . � _i ; _ i ! I t I ! 11111 ? E I i I I 1 l : i ; E ` ) � . I , � . � ! il , : Til 30 E I ; l� ; ! FI , Ii f iII ; I l ; . iijll T t ' ` ! I I III ! 35 I 1 1 I ' . il '-T--- Il• i - ; fti I1 ii I ! � } ! E —40 1 ! : ! ; ! II ! IE! 0 0.5 1.0 I 24N.-OD SPUTSPOON SAMPLER © TORVANE SHEAR I STRENGTH,TSF (TONS PER FT li 3•1N.-OD THIN-WALLED SAMPLER ® UNDRAINED SHEAR G GRAB SAMPLE OF DRILL CUTTINGS STRENGTM,TSF 8 NX CORE RUN * No RECOVERY ,`R BORING B-1 I—SLOTTED PVC PIPE ��wd T =` Water Level(date) L Lweuetarn OCT. 2004 JOB.NO. 4134 FIG. 3A • STD PENETRATION RESISTANCE 8 CLASSIFICATION OF MATERIAL 0 (140•1B WEIGHT,304N.DROP) L iL g y A BLOWS PER FOOT = c _,°� • MOISTURE CONTENT,% o g SURFACE ELEVATION 359 ft (t) o @§ ar 0 50 100 ";1.''• FILL:Medium dense,brown,silty GRAVEL;fine to coarse, I ' :''•le::; trace fine-grained sand , i .r . V":l'. to reddish-brown silt matrix below 5 ft 5 �. own s I S-3 I5 .-^ 9.0 •--- 10—' • Stiff,brown mottled rust SILT;trace fine-grained sand and clay — s- T� i , I _ — brown below 12.5 ft ;I • . • 15— — — • S-a _ reddish brown,dayey,some fine-to medium-grained * = . —A d sand at 17 ftT 18.5 ST 1 0=- ` _++++ Very soft to soft(RH-1),gray,rust and brown BASALT; f . . 'I I i 20 —++++ severely weathered,in matnx of clayey sand _ th • ++++ —_:_• 7 1 r i —++++ _ I I I T ' — _++++ : • _ j 1 ++++ -; j I i 1 25— S-9 I , , +r0/4 A + ! III : ,I : , -H ' I + ++ I I —++++ i ' • I I ; ; l • li —++++ -71---r-: ;�i-,. ! i • ! j • _ -1—i-1 ' I 30—++++ —t' I I i i II ` — 30.3 S-10 x Ii ! , I �Iii11 .s A (8124/2004) _t_t 1 1 , I i i i I — ��. _, ! , 1 ! Ii r1 , jl = i; ; i ! iii{ 35-- 1 i .— i j , l( : i I t j ' I 1 —40 — ; , ; f; i ' ii ! 1 : 1 I 2-IN.-00 SPLIT-SPOON SAMPLER ® TORVANE SHEAR 0 0.5 1.0 STRENGTH,TSF U 10L-00 THaN-ALLIED SAMPLER (TONS PER FT 2) ® . UNDRAINED SHEAR G GRAB SAMPLE OF DRILL CUTTINGS STRENGTH.TSF * NO RECOVERY •y �._ ""`"��" G BORING B-2 t—SLOTTED PVC PIPE I �A'aid L'"dMan Covri .- __ Water Level(date) OCT. 2004 JOB.NO. 4134 FIG.4A STD PENETRATION RESISTANCE CLASSIFICATION OF MATERIAL (140 WEIGHT,3041.DROP) l J I $ N A BLOWS PER FOOT • MOISTURE CONTENT,% 1 SURFACE ELEVATION 310 ft (i) c3 1 0 50 100 - Stiff to very stiff,brown mottled rust SILT;trace clay and fine- • ! + i — grained sand,scattered organics,4-in.-thick heavily rooted . .__ ,- ! — zone at the ground surface • • , I I • 5— organics absent below 5 ft • I : : — sz I[ 1 ; . . ', ' . 1 - 1 , S-3 1_444 ; � • is • l : : . — —some gravel and cobbles below 13 ft S-S ii ;1: • ; 1 ; I - — I m+-4-"- 14.0 ; 1 � i ;TII � 1 15—++++ Medium soft to medium hard(RH-1 to RH-2)BASALT;severely � � � 1 I 1 -++++ weathered T• I , , I 1 1 1 = 1 1 . ++++ Tf 17 —t 7- —T' ' ; 1 ! it I � � I —+++t iiI ! i l i I I —++++ r-1 1 . 1 I I I . —++++ i i ' ? I I r ! 20—NI+++ 1 1 1 1 1 1 1 1 20.2 S 1 s 1 1 ` SOr�J► — (9/10/2004) 1 • --- ; � t1 ! li rl •••• • : iF (+ 1 — 1 1 I 1 HI : � 25— ! : ; ; 1 , f I 1I ; I i ? — i ! IIli II II 1 ; i {I I . 1 H1II ; I i ' I i t l 1 30— I1 II II 1 I � IlI I _ —T ! I . - 1 —40 I I . , 0 0.5 1.0 I 244-01)SPLIT-SPOON SAMPLER 0 TORVANE SHEAR II 34L-0D THIN-WALLED SAMPLER TSF (TONS PER FT - ® UNDRAINED SHEAR G GRAB SAMPLE OF DRILL CUTTINGS STRENGTHi TSF * NO RECOVERY RUN R BORING B-3 I—SLOTTED PVC PIPE IL�-wd V Water Level( ) Raft Lird OCL 2004 JOB.NO. 4134 FIG.SA BORING SAMPLE DEPTH,FT MOISTURE CONTENT, % DRY UNIT WEIGHT,PCF SOIL DESCRIPTION (INITIAL) (FINAL) (INITIAL) (FINAL) 8-3 5-2 5.5 25 25 97 104 STIFF,BROWN MOTTLED RUST SILT;TRACE FINE-GRAINED SAND AND CLAY STRESS,TONS/FT 2 0.01 0.1 1 10 100 .. Ka w .1. u, an vas,o N w is a., o, r CO 5o H w . V, o. V CO,o..... .v W AS to a v Oa'o `er -- -- ------ °"•••• !)- -- __-- - - - _�- _ o.. I o� - - - --- -__ _-— _ — - - '- Z -tOt ---- — _..-_ _...... ._ _... ~. .�� o�� ,771-- O - _ 0 hi ___, --. — . 20 ., [ . ; G Re — r_ CONSOLIDATION TEST _ .___. .__ I i BORING 13.3,SAMPLE 5-2(5.5 Fl) - .-- - _- _ - ... - --_-�•--- I i 30 - -_ - - -- -. . _... ... .. _ .__ i 1 I ' OCT.2004 JOB NO.4134 FIC.6A