GEOTECHNICAL REPORT Loup Loup Bridge Replacement Okanogan County, Washington

Transcription

1 GEOTECHNICAL REPORT Loup Loup Bridge Replacement Okanogan County, Washington Prepared for: Nicholls Engineering Project No May 15, 2014

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3 ASPECT CONSULTING Contents 1 Introduction Scope of Services and Authorization Project Description Site Conditions General Geology Seismicity Surface Field and Laboratory Investigations Soil Boring Creek Bank and Channel Samples Laboratory Testing Subsurface Conditions Stratigraphy Groundwater Conclusions and Recommendations General Earthquake Engineering Ground Motion Seismic Hazards Bridge Approach Embankments Settlement Beneath Approach Embankments at Abutments Slope Stability Foundations Alternatives Bridge Abutment Loads Scour Depth Minimum Pile Penetration Driven Pile Axial Resistance Pile Settlement Driven Pile Lateral Resistance Drivability Bridge Abutment and Wingwall Design Backfill and Drainage Material Lateral Earth Pressures Earthwork Temporary Excavation Slopes Structural Fill and Compaction PROJECT NO MAY 15, 2014 i

4 ASPECT CONSULTING 6 Construction Considerations General Driven Pile Installation Geotechnical Monitoring of Driven Piles Site Subsurface Variation and Pile Lengths References Limitations List of Tables 1 Ground Motion Parameters Liquefaction Susceptibility Earthquake Parameters Bridge Abutment Loads Resistance Factors for Driven Pile Design Lateral Pile Analysis Soil Parameters Lateral Earth Pressure Parameters List of Figures 1 Site Location Map 2 Site and Exploration Map 3 Estimated Axial Pile Nominal Resistance Driven, Closed-End, 18-inch Diameter, Steel Pipe Pile 4 Lateral Pile Deflection Profile - Driven, Closed-End, 18-inch Diameter, Steel Pipe Pile 5 Lateral Pile Shear Resistance Profile - Driven, Closed-End, 18-inch Diameter, Steel Pipe Pile 6 Lateral Pile Moment Profile - Driven, Closed-End, 18-inch Diameter, Steel Pipe Pile List of Appendices A B Subsurface Explorations Laboratory Test Results ii PROJECT NO MAY 15, 2014

5 ASPECT CONSULTING 1 Introduction This report presents the results of a geotechnical engineering study performed by Aspect Consulting, LLC (Aspect) for the Loup Loup Bridge Replacement project in Okanogan County, Washington. Our services were provided in support of an engineering study being performed by Nicholls Engineering (Nicholls) for Okanogan County Public Works (County). The project involves the removal and replacement of the Loup Loup Bridge (bridge), as a part of Loup Loup Canyon Road in Section 36, Township 34 N, Range 24 in Okanogan County, Washington. The project location is shown on Figure 1, Site Location Map. The new bridge will cross over Loup Loup Creek to the southwest of the existing bridge location. This report summarizes the results of the completed field explorations and presents Aspect s geotechnical engineering conclusions and recommendations. 2 Scope of Services and Authorization We completed this study in general accordance with our Subconsultant Agreement and Scope of Work that was authorized on October 30, Project Description The project site (Site) is located along Loup Loup Canyon Road roughly located about 10 miles west of the city of Okanogan and approximately 4.15 miles north of the junction with Washington State Route 20 at an approximate Latitude , Longitude Loup Loup Canyon Road crosses Loup Loup Creek (creek) via an existing 40-foot-span steel bridge. As part of this project, the existing bridge will be removed and replaced by a new concrete bridge (bridge) with a 52-foot span that is 28 feet wide and will be supported on abutments on each side of the creek. The centerline of the new bride will be about 40 to 45 feet southwest of the existing bridge. The new bridge deck will be at about Elevation 1001 to 1002 feet. An approach embankment up to 7 feet tall will be added to each side of the new bridge location and will be retained by wingwalls. The layout of the Site and new bridge is shown on Figure 2, Site and Exploration Map. We understand the new bridge will be designed in accordance with the current American Association of State Highway and Transportation Officials LRFD Bridge Design Specifications (AASHTO BDS), and Load and Resistance Factor Design (LRFD) methodology. PROJECT NO MAY 15,

6 ASPECT CONSULTING 4 Site Conditions 4.1 General Geology The Site is located on the eastern slope of the north Cascade Mountains in a canyon named Loup Loup Canyon. The canyon was formed by glacial incision of the Cretaceous granodiorite (Ki gd ) bedrock that is mapped in the area (DNR, 2014) and outcrops to the north, east and west of the site. The incised bedrock is mapped as being in-filled with Pleistocene continental drift (Q gd ) consisting of unconsolidated glacial debris, including till, glaciofluvial sand and gravel, and glaciolacustrine silt and clay (DNR, 2013) at the site. Although not mapped, recent (post-glacial) alluvium (Q a ) associated with Loup Loup Creek, is expected. Soil units are described in more detail below in Section 4.4, Subsurface Conditions. 4.2 Seismicity Rocks in the project area were deformed by tectonic uplift of the Cascade Mountains, beginning in the late Eocene epoch (approximately 37 million years ago) that resulted from collision of oceanic tectonic plates with the North American continental plate. The Cascadia subduction zone (CSZ) marks the seismically active margin between these crustal plates. The Site is located within this active seismic zone and is subject to earthquakes on shallow crustal faults in addition to those within the CSZ. A shallow crustal earthquake with an estimated magnitude of 6.8 (Bakun, et al., 2002) occurred in 1872, south of the Site near the town of Entiat. The fault responsible for the 1872 earthquake has not been identified, but it is considered capable of producing future earthquakes. According to the U.S. Geological Survey, the largest future earthquakes within the region would likely be generated by shallow crustal faults and could exceed magnitude 7. Other large earthquakes in Washington have been associated with the CSZ, which lies approximately 150 miles to the west of the Site (DNR, 2008). Hazards associated with the CSZ include deep earthquakes and subduction zone earthquakes. Deep earthquakes, which occur from tensional rupture of the sinking oceanic plate, typically have magnitude 7.5 or less and occur approximately every 10 to 30 years. The Site area is generally protected from strong shaking caused by these earthquakes by the great depth to the hypocenter. Subduction zone earthquakes occur due to rupture between the subducting oceanic plate and the overlying continental plate. These earthquakes have magnitude up to 9 and a recurrence interval on the order of 500 years. The last great subduction zone earthquake in Washington occurred about 300 years ago. 2 PROJECT NO MAY 15, 2014

7 ASPECT CONSULTING Due to the lengthy recurrence intervals between large seismic events, the potential for strong ground shaking is considered low during the life of the proposed Project, but must be considered for design of the structure, as required by AASHTO BDS. 4.3 Surface The Site consists of a rural unpaved road (Loup Loup Canyon Road) surrounded by forested land, rock outcrops, and the Rock Creek Campground to the south. Loup Loup Canyon Road crosses Loup Loup Creek generally in the north-south direction via the existing Loup Loup Bridge. The Loup Loup Creek channel is approximately 30 to 35 feet wide. Vegetation at the site consists of evergreen trees, shrubs and grass. Topography of the Site and layout of the existing and proposed bridge is illustrated on Figure Field and Laboratory Investigations Soil Boring On November 5, 2013, we performed a geologic reconnaissance and completed one soil boring (B-1) to a depth of 61.5 feet below the existing ground surface on the south side of Loup Loup Creek, using mud-rotary auger drilling techniques. The boring was completed at the west extent of Loup Loup Canyon Road, about 25 feet from the longitudinal centerline of the proposed bridge. A second boring was planned on the north side of the creek but the existing bridge load rating was not capable of supporting the drill rig to cross the bridge and snowy road conditions prevented access from the road to the north. The location of the soil boring B-1 is shown on Figure 2. Appendix A describes the field exploration methodology in greater detail and contains the log for soil boring B Creek Bank and Channel Samples During our geologic reconnaissance we collected soil samples from the creek bank and channel using hand tools approximately 25 feet upstream and 25 feet downstream of the new bridge location for characterization and scour analysis completed by Nicholls Laboratory Testing Select soil samples collected from soil boring B-1 and the creek bank and channel soil samples were submitted to a soil testing lab to determine the selected properties of the soil samples including moisture content, grain size analysis, organic content and plasticity (Atterberg Limits). The results of the geotechnical laboratory testing are shown in Appendix B. 4.5 Subsurface Conditions Subsurface conditions at the project site were inferred from the field and laboratory investigations accomplished for this study, visual reconnaissance of the Site, and review of applicable geologic literature. More detailed soils descriptions are presented on the boring log in Appendix A. PROJECT NO MAY 15,

8 ASPECT CONSULTING The following section presents more detailed subsurface information organized from the upper to the lower soil types Stratigraphy In general, the descriptions from geologic maps and literature for the area corresponded with the data produced by the soil boring completed for the project. Subsurface soils can be grouped into two units consisting of artificial fill and alluvium deposits. Bedrock was not encountered in the exploration. Details of the composition and distribution of these units are presented in more detail below Artificial Fill (Af) Artificial fill was encountered from the ground surface to a depth of 4.5 feet below the ground surface. The fill generally consists of 10-inch layer of dense, gray, sandy GRAVEL (GP) 1 road base overlying medium dense, brown, slightly silty, slightly gravelly, SAND (SW-SM). The fill was placed to construct the existing bridge approach embankment. From our geologic reconnaissance and topographic survey (by others) it appears that artificial fill layer is likely thinner or not present at the new bridge abutment locations Alluvium Deposits (Q a ) Below fill, we encountered recent alluvium (Q a ) associated with Loup Loup Creek. The alluvium deposits consisted of loose to medium dense, brown and gray SAND with variable silt and gravel content and occasional thin organic silt lenses and organic matter (SW, SP, SW-SM, SP-SM); and stiff, gray, non-plastic SILT (ML). These materials have low to moderate strength and are expected to behave elastically when loaded. Within the alluvium we encountered a layer of stiff, dark brown, non-plastic, organic SILT (OL) at depths between 38 and 43 feet. This layer is relatively weak and compressible Groundwater Groundwater level was observed during drilling at a depth of 10 feet below grade at about Elevation 992 feet. The groundwater was observed to be a near the water level observed in Loup Loup Creek at the time of drilling. The groundwater level may fluctuate by several feet with seasonal changes and water levels in Loup Loup Creek. 1 Soil Classification per the Unified Soil Classification System (USCS). Refer to ASTM D PROJECT NO MAY 15, 2014

9 ASPECT CONSULTING 5 Conclusions and Recommendations 5.1 General To provide for scour protection, the base of the bridge foundations must be below the creek thalweg. This would require a significant amount of excavation and dewatering to construct shallow foundations to support the bridge. Therefore, we recommend the bridge be supported on deep foundations. The following sections present the results of our studies and geotechnical engineering analyses. The recommendations are meant to support engineering design activities. 5.2 Earthquake Engineering Ground Motion The AASHTO BDS response spectrum for design is based on local seismicity and soil conditions. The seismicity is represented by the acceleration coefficient, A s, which represents the peak ground acceleration (PGA) based on established seismic risk models adjust for site conditions. The United States Geologic Survey (USGS, 2008) completed regional probabilistic ground motion studies to establish the PGA for various recurrence intervals equating to 7 percent occurrence in 75 years (approximately a 975-year return period event). The AASHTO BDS expresses the effects of site-specific subsurface conditions on the ground motion response in terms of the Site Coefficients. The Site Coefficient accounts for the seismic response of the soil profile and is based on the density and stiffness of the soil profile underlying the site. The Soil Type can be correlated to the average standard penetration resistance (NSPT) in the upper 100 feet of the soil profile. We characterize the site as AASHTO Site Class D. AASHTO BDS Site Coefficients for Site Class D have been utilized to adjust the mapped PGA, and spectral accelerations at periods of 0.2 (S s ) and 1.0 (S 1 ) seconds at the Site, as shown in Table 1. PROJECT NO MAY 15,

10 ASPECT CONSULTING Table 1 Ground Motion Parameters Design Parameter Recommended Value Site Class D (1) Peak Ground Acceleration (PGA) 0.152g Short Period Spectral Acceleration (S s ) 0.352g 1-Second Period Spectral Acceleration (S 1 ) 0.108g Site Coefficient F pga 1.50 (Site Class D) Site Coefficient F a 1.52 (Site Class D) Site Coefficient F v 2.37 (Site Class D) Effective Peak Ground Acceleration (A s ) 0.228g (Site Class D) Design Short Period Spectral Acceleration (S Ds ) 0.535g (Site Class D) Design 1-Second Period Spectral Acceleration (S D1 ) 0.256g (Site Class D) Notes: (1) Based on Table of the AASHTO Seismic Bridge Design Manual Seismic Hazards Earthquake-induced hazards that are relevant to the Site include fault rupture, soil liquefaction and associated effects. As discussed in the following sections, neither of these represent design considerations Surficial Fault Rupture Faults that could produce surface rupture in the project area are not well-defined and are thought to have recurrence intervals in the range of one to several thousand years. The current state of engineering practice in Washington State is such that surface fault rupture is only considered in extraordinary cases with established evidence or high likelihood that a fault is present within the project area; which is not the case for the Site. In our opinion, the relative risk of fault rupture at the surface of the Site is low Soil Liquefaction Susceptibility Liquefaction occurs when loose, saturated and relatively cohesionless soil deposits temporarily lose strength as a result of earthquake shaking. Potential effects of soil liquefaction include temporary loss of bearing capacity and lateral soil resistance, liquefaction-induced settlement, and sand boils, any of which could result in significant structural damage. Primary factors controlling the development of liquefaction include intensity and duration of strong ground motion, characteristics of subsurface soil, in-situ stress conditions and the depth to groundwater. 6 PROJECT NO MAY 15, 2014

11 ASPECT CONSULTING Liquefaction susceptibility evaluations were conducted with the aid of WSliq, a seismically induced liquefaction and settlement analyses software program that was created as part of an extended research project supported by the Washington State Department of Transportation (WSDOT), and liquefaction models by Youd et al., 2001, and Idriss and Boulanger, We evaluated liquefaction potential based on the design seismic event shown in Table 2 below. The design level event is based on the USGS National Seismic Hazard Map (USGS 2008) data to obtain earthquake magnitude and source. The Effective Peak Ground Acceleration (A s ) was determined using the methodology shown in section Ground Motions of this report. Table 2 Liquefaction Susceptibility Earthquake Parameters Seismic Event Return Period (years) Effective Peak Ground Acceleration (g) Earthquake Magnitude (1) Modal Source-to-Site Distance (km) (1) 975 2) (3) Notes: (1) Based on USGS Probabilistic Seismic Hazard Deaggregation (2008). (2) As required by the AASHTO BDS and WSDOT GDM. (3) As calculated in Ground Motion section of this report. Our analyses indicate that the average factor of safety (FS) against liquefaction is greater than 1.25, indicating that risk of liquefaction is low at this site. 5.3 Bridge Approach Embankments We understand that bridge approach embankment will be constructed at each bridge end and will require up to 7 feet of fill near the abutments. As described in the Subsurface Conditions section of this report, a compressible layer of non-plastic, organic SILT (OL) was observed between at depths between 38 and 43 feet below ground surface, corresponding to Elevation 959 to 964 feet and is expected to undergo some compressive settlement under the new embankment loads Settlement Beneath Approach Embankments at Abutments The approach embankments will impose new load onto the layer of compressible organic SILT which will result in ½- to 1 inch of primary consolidation settlement, and ½-inch of secondary, long-term settlement, at the bridge abutments. We estimate that approximately half of the total primary consolidation settlement (i.e. ¼ to ½ inch) will occur within a few weeks of placing the full approach embankment. Secondary long-term compression settlement will occur over many years after placing the approach embankments. Given that this roadway approach is unpaved, we anticipate such settlements will be tolerable, if even noticeable. PROJECT NO MAY 15,

12 ASPECT CONSULTING Long term settlement will introduce negative skin friction (downdrag load) on the pile foundations. Downdrag considerations are discussed in the Foundations section of this report Slope Stability We understand from the preliminary bride layout shown on Figure 2 that the creek bank slopes will be inclined at approximately 2H:1V (Horizontal:Vertical) after the bridge approach embankments are placed. We analyzed the post-construction static and seismic slope stability of this configuration using the limit equilibrium software SLIDE. The groundwater level was adjusted between Elevation 990 feet (creek empty) and 995 feet (100 year flood event) to capture a range of groundwater and creek flow conditions. The seismic horizontal acceleration coefficient (k h ) was taken as 50 percent of the effective peak ground acceleration (A s ) per AASHTO BDS Section The results of the slope stability analyses show that the factor of safety is greater than 1.5 for the static condition, and greater than 1.1 for the seismic condition, for the groundwater levels considered, indicating adequate global stability of the embankments. 5.4 Foundations Alternatives Foundation selection and design for the proposed structures must consider the design loads, constructability, construction impacts (nearby facilities, infrastructure, and habitat), and cost. We evaluated shallow and deep foundations, including spread footings, drilled shafts, and driven steel piles. Based on the requirement to found bridge foundations below the creek thalweg, and the compressible nature of a layer within the subsurface underlying the new bridge abutments, we recommend a deep foundation system to support the new bridge. Deep foundations eliminate the need for large, deep excavations, and dewatering needed to construct shallow foundations below the thalweg. Considering deep foundations, a driven pile foundation system is a feasible and relatively cost effective option over drilled shafts because installation won t require drilling with full-depth casing to mitigate caving of wet sands present at this Site. Driven piles are installed relatively quickly and there are practical ways to verify their capacity in the field during construction. Driven piles commonly used include steel H- piles, steel pipe piles (driven, steel-walled pipes that are in-filled with reinforced concrete and are also known as cast-in-place concrete piles) and pre-cast, pre-stressed concrete piles. Given the rural project location, damage to adjacent facilities from pile driving vibrations does not pose a significant concern. The relative cost advantage of driven pile types fluctuate with the price of steel and concrete. Steel pipe piles have advantages in that they are durable, easy to splice, and if driven closed-ended, can be inspected from the interior after driving. They have also been shown to resist cyclic loads more effectively than pre-cast, pre-stressed concrete piles. Steel piles are vulnerable to corrosion unless they are appropriately protected. Pre-cast, pre-stressed concrete piles are more resistant to corrosion than steel piles. However, they 8 PROJECT NO MAY 15, 2014

13 ASPECT CONSULTING are somewhat brittle, must be handled carefully, and are difficult to splice. Concrete piles also require at least a 1-month lead time for casting and curing. Non-displacement steel H-piles are not favorable for this site because they will not develop as much axial capacity compared to displacement piles Of the two remaining options (driven steel pipe and pre-cast concrete), we understand that driven, closed-end steel pipe piles in-filled with concrete are a preferred option for this project by Nicholls, and given the site conditions and project objectives, may be the most cost effective choice for use in a driven pile foundation system. Our evaluations indicate an 18-inch diameter pile of this type is adequate to support the bridge abutment loads discussed in the following section Bridge Abutment Loads Design concept for the new bridge includes a concrete, single-span, pile supported bridge structure. According to Nicholls, the preliminary bridge design calls for a 52-foot span supported by abutments on each side of the creek. At the time of this report, we understand the abutment loads are as shown in Table 3. Table 3 Bridge Abutment Loads LRFD Limit State Dead Load (kips) Live Load (kips) Total (kips) Service Strength Downdrag Loads As discussed above, the approximately 7-foot-thick approach embankments will trigger settlement within the compressible organic SILT layer. As settlement occurs after pile installation the side resistance between the pile skin area and the soil profile will act in the negative direction and produce a downdrag load on the pile. We estimate the unfactored downdrag load (R Sdd ) to be approximately 200 kips for the 18-inch diameter closed-end steel pipe piles being considered. There are two ways to approach designing for downdrag: 1) The piles would be driven to a sufficient depth below the compressible organic silt layer to develop the required axial capacity to resist the combined downdragplus-bridge structural loads, without appreciable settlement. In this approach, downdrag is considered as a permanent load on the piles. 2) The piles are driven to some nominal shallower depth, sufficient to resist structural axial and lateral loads conditions only. In this scenario, the piles are PROJECT NO MAY 15,

14 ASPECT CONSULTING expected to settle along with the surrounding soil profile, thereby precluding the development of negative skin friction along the pile section. Due to site and weather constraints at the time of our field investigation, we do not have sufficient subsurface data to estimate the required pile depths to resist combined downdrag-plus-structural loading conditions. Normally, in this situation, we would advocate that a contingency be placed on the required pile lengths, and a test pile program be undertaken to evaluate required pile embedment depths before the remaining production piles are installed. Based on our conversation with Jerry Nicholls of Nicholls, we understand that approach option 2 (shown above) is preferred by Nicholls and the County. In this scenario, the likely construction sequence will be to backfill the abutments and raise roadway approach grade, after the piles have been driven. This sequence will trigger consolidation settlement within the compressible organic SILT layer. We understand further that estimated long-term pile and abutment settlement of up to 1 inch will be acceptable. In this case downdrag need not be considered a design load in determination of static geotechnical resistance required for the LRFD limit states Scour Depth Hydraulic modeling results provided by Nicholls indicate scour action at the new bridge abutments will incise bank soils down to approximately Elevation 988 feet. Axial and lateral pile resistance should be neglected through the scour zone from top of pile to scour elevation. Pile side resistance developed over the scour zone (R scour ) should be accounted for during pile installation as it must be overcome during pile driving through the future scour zone soils. We estimate the side resistance over the scour zone, R scour, is equal to approximately 20 kips for a driven, closed-end, 18-inch diameter steel pipe pile Minimum Pile Penetration We recommend that the piles be driven at least nominally five pile diameters deeper than the bottom of the compressible organic SILT layer observed to be present between Elevation 959 and 964 feet. This equates to a recommended minimum pile tip Elevation of 952 feet. Piles may need to be driven deeper than the minimum pile tip elevation to develop the required geotechnical resistance. Actual pile depths will need to be evaluated in the field Driven Pile Axial Resistance Axial pile resistance analyses were completed for a driven, closed-end, 18-inch diameter, steel pipe pile in accordance with AASHTO BDS guidelines. The analyses were performed using the Federal Highway Administration (FHWA, 2007) Driven Analysis Program, using the soil conditions observed in geotechnical boring B-1. The results of our axial resistance analyses are nominal (ultimate) resistances for both bearing (compression) and uplift (tension) resistances for a single pile or pile groups with a minimum 2.5 diameter center-to-center spacing. The estimated nominal resistance is a 10 PROJECT NO MAY 15, 2014

15 ASPECT CONSULTING sum of the frictional resistance along the side of the pile and the end resistance and is shown on Figure 3 - Estimated Axial Pile Nominal Resistance. The applicable Resistance Factors corresponding to the strength, service and extreme limit states are shown in Table 4 and can be used in conjunction with Figure 3 to determine estimated strength, service and extreme geotechnical resistances at various pile embedment depths. Pile embedment was assumed to begin at Elevation 998 feet. Pile skin resistance was neglected through the scour zone extending down to Elevation 988 feet. It is important to understand that the nominal resistances shown on Figure 3 are estimates based on static analysis methods from geotechnical boring B-1 located on the south side of the bridge. It is possible that soil conditions may vary locally at the south and north abutments and pile resistance should be confirmed by field observations made during driving as discussed in Section 6.3 Geotechnical Monitoring of Driven Piles. Table 4 Resistance Factors for Driven Pile Design Notes: Resistance Factor, ϕ Limit State Bearing Resistance, (1) ϕ stat Bearing Resistance, (2), ϕ dyn Uplift, ϕ up Strength (3) /0.55 (4) 0.35 Service Extreme (1) Applies to nominal resistance as determined by static analysis methods (see Figure 3). (2) Applies to nominal resistance as determined by dynamic analysis methods during pile driving. (3) Assumes wave equation analysis without pile dynamic measurements or load test but with field confirmation of hammer performance. (4) Assumes the WSDOT driving formula will be used as the basis for the dynamic analysis and pile driving construction control Pile Settlement If the piles are not driven to a sufficient depth into incompressible sand below the organic SILT layer to fully resist downdrag plus structural loads, pile settlement should be anticipated. In this case, the pile settlement will be less than or equal to the estimated total settlement of soil profile. Constructing the approach embankments before the piles are driven, will allow some of the primary consolidation settlement to take place, and will reduce the magnitude of potential pile settlement Driven Pile Lateral Resistance Driven pile lateral resistance is developed from the material stiffness of the pile itself and the embedment soils. The magnitude of resistance depends on the type of, center-tocenter pile spacing, pile head fixity condition, and tolerable deflections. We analyzed a steel, 18-inch diameter pile using the computer program LPILE (Ensoft, 2013). PROJECT NO MAY 15,

16 ASPECT CONSULTING We considered the steel pile wall thickness to be reduced by from ½-inch to 3/8-inch steel to account for possible long-term corrosion. Per Nicholls, the pile core was modeled as being in-filled with 4,000 psi structural concrete and a minimum of five, #6 size steel vertical reinforcing bars extending from the pile head to a depth of 25 feet. Both fixed and free pile head fixity conditions were considered. The embedment soils were modeled in LPILE using the parameter shown in Table 5 below. Lateral resistance over the scour zone was neglected. Table 5 Lateral Pile Analysis Soil Parameters Layer Soil Type Top of Layer Elevation (ft) Bottom of Layer Elevation (ft) Effective Unit Weight, g (pcf) Internal Friction Angle, F (degrees) Strain at 50%, e 50 p-y Modulus, (pci) 1 Sand (API) n/a 68 2 Sand (API) n/a 48 3 Stiff Clay with Free Water (Reese) n/a Sand (API) n/a 48 We understand from Nicholls that the center-to-center pile spacing will be 6.25 feet, equating to a spacing of 4.2B, where B is the diameter of the pile. Pile group interaction effects were taken into account by applying a P-multiplier value (P m ) of 0.92 per Table of the AASHTO BDS because the pile spacing is less than 5B. The results of the lateral piles analysis are shown on Figure 4, 5, and 6 plotting pile Elevation versus deflection, shear resistance, and moment, respectively, for this proposed spacing. The plots are provided for normal (static) conditions and are nominal resistances (unfactored) Drivability In our opinion, the Site is suitable for pile driving. Once a contractor has been selected for pile installation a wave equation analysis should be completed to determine if the contractor s proposed pile driving system is capable of driving the piles in accordance with WSDOT Standard Specifications Section As a starting point for selection, we recommend the pile driving hammer have a minimum rated energy of 55,000 foot-pounds. We recommend that driven pile resistance be confirmed using wave equation analysis, and the WSDOT pile driving formula shown in WSDOT Standard Specifications Section PROJECT NO MAY 15, 2014

17 ASPECT CONSULTING 5.5 Bridge Abutment and Wingwall Design Backfill and Drainage Material Measures should be taken to prevent buildup of hydrostatic pressure behind abutments and wingwalls. Abutment and wingwall backfill materials should consist of material meeting the requirements of Gravel Backfill for Walls as specified in Section (2) of the WSDOT Standard Specifications. Placement and compaction of fill behind walls shall be in accordance with Section (7) of the WSDOT Standard Specifications for Road, Bridge, and Municipal Construction. Over-compaction of the backfill behind walls should be avoided. We recommend compacting backfill behind walls to approximately 95 percent of MDD as determined in accordance with WSDOT Standard Specifications Section (14). Heavy compactors and large pieces of construction equipment should not operate within several feet 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 unique surcharge loads, such as heavy construction equipment, should be considered on a case-by-case basis by the structural engineer Lateral Earth Pressures Lateral earth pressures acting behind the abutment and wingwalls are presented in Table 6 below and represent the active, at-rest, passive, and seismic. PROJECT NO MAY 15,

18 ASPECT CONSULTING Table 6 Lateral Earth Pressure Parameters Earth Pressure Condition Earth Pressure Coefficient Equivalent Fluid Weight (1) (pcf) Earth Pressure (2) (psf) Surcharge Pressure (psf) Active (K a ) (3) H 0.28S (8) At-Rest (K o ) H 0.44S (8) Passive (K p ) (4) (5) 300D (5),(6),(7) - Active Seismic (K ae ) (9) - 4.2H - At-Rest Seismic (10) - 9.3H - (K ae ) Notes: (1) Granular backfill placed as structural fill with a unit weight of 125 pcf is assumed. (2) Static earth pressures result in a triangular pressure distribution along the height of the wall. Seismic earth pressures result in a uniform rectangular pressure distribution along the height of the wall (H) with the resultant acting at a height of 0.5H above base of the wall. (3) To invoke the active conditions the wall must rotate about the base with a lateral movement at the top of the wall of approximately 0.002H, where H is the height of the wall. (4) To invoke the passive conditions, the wall must move into the backfill with a lateral movement of approximately 0.020H. (5) Ultimate passive pressures are presented; a strength limit state resistance factor (ϕ ep) of 0.50 should be applied for design. (6) Where D is the depth of embedment of wall below finish grade. (7) Passive pressure should be ignored within 24 inches below finish grade. (8) Resulting uniform surcharge acting along the height of the wall, where S is the surcharge pressure. Seismic and surcharge pressures are typically not considered concurrently in design unless specific conditions dictate otherwise. (9) The seismic pressures were calculated in accordance with Chapter 11 and Appendix A of the AASHTO BDS where the wall is capable of displacements of 1.0 to 2.0 inches of more during the seismic event using the design earthquake parameters shown in Tables 2 and 3. (10) The at-rest seismic pressure assumes wall is not free to translate or move during the seismic event. 5.6 Earthwork Based on the explorations performed on site and our understanding of the project, it is our opinion that the contractor should be able to complete site earthwork with standard construction equipment. Appropriate erosion and sedimentation control measures should be in accordance with the local best management practices (BMPs) and should be implemented prior to beginning earthwork activities Temporary Excavation Slopes Maintenance of safe working conditions, including temporary excavation stability, is the responsibility of the contractor. All temporary cuts in excess of 4 feet in height that are 14 PROJECT NO MAY 15, 2014

19 ASPECT CONSULTING not protected by trench boxes or otherwise shored, should be sloped in accordance with Part N of Washington Administrative Code (WAC) With time and the presence of seepage and/or precipitation, the stability of temporary unsupported cut slopes can be significantly reduced. Therefore, all temporary slopes should be protected from erosion by installing a surface water diversion ditch or berm at the top of the slope if precipitation is expected. In addition, the contractor should monitor the stability of the temporary cut slopes and adjust the construction schedule and slope inclination accordingly. Vibrations created by traffic and construction equipment may cause caving and raveling of the temporary slopes. In such an event, lateral support for the temporary slopes should be provided by the contractor Structural Fill and Compaction We estimate a portion of material excavated for the project may be suitable as structural fill. On-site soils may be made into suitable structural fill by moisture conditioning to near the optimum moisture content. Excavated material should be visually inspected by the geotechnical engineer to determine its potential use as backfill. Excavated material that is unsuitable as structural fill may be suitable as backfill for unimproved areas that are not susceptible to differential settlement over time. In general, suitable structural fill material for the project is fill placed within 3 percent of its optimum moisture content per Standard Specifications Section (14) and does not contain deleterious materials, or greater than 5 percent organics. General import material should be in general conformance with Section (3), Common Borrow, of the WSDOT Standard Specifications. In wet weather conditions, or situations requiring a more free-draining backfill, Gravel Borrow in accordance with Section (1) of the WSDOT Standard Specifications should be imported for use as fill. The procedure to achieve the specified minimum relative compaction depends on the size and type of compacting equipment, the number of passes, thickness of the layer being compacted, and certain soil properties. When size of the excavation restricts the use of heavy equipment, smaller equipment can be used, but the soil must be placed in thin enough lifts to achieve the required compaction. Generally, loosely compacted soils are a result of poor construction technique or improper moisture content. Soils with a high percentage of silt or clay are particularly susceptible to becoming too wet, and coarse-grained materials easily become too dry, for proper compaction. Silty or clayey soils with a moisture content too high for adequate compaction should be dried as necessary, or moisture conditioned by mixing with drier materials, or other methods. PROJECT NO MAY 15,

20 ASPECT CONSULTING 6 Construction Considerations 6.1 General There is a possibility that construction of the geotechnical project elements will be impacted by the presence of relatively shallow groundwater, and obstructions to pile driving, and logistics with crossing over the creek due to the relatively low rating of the existing bridge. These potential difficulties should be appropriately addressed in the contract documents. All pile installations, final abutment slope grading, and structural fill placement should be evaluated by the project geotechnical engineer and completed in accordance with the WSDOT Standard Specifications. 6.2 Driven Pile Installation In general, pile driving construction should follow the guidelines set forth in WSDOT Standard Specifications Section Installation of piles may be impacted by the potential presence of obstructions (intact wood debris or gravels). Obstructions encountered during pile driving may cause some of the piles to be driven out-of-plumb, or to drift off of the design horizontal location. Also, if significant obstructions are encountered at certain locations, it may be necessary to adjust certain pile locations to avoid the obstructions. Because of this potential effect, some flexibility should be allowed in the design to enable adjustment of pile locations. In certain instances, it may be necessary to alter the size of the pile cap to accommodate the new pile locations. Any such situations which arise during construction should be evaluated on a case-by-case basis by the owner, structural engineer, and geotechnical engineer. 6.3 Geotechnical Monitoring of Driven Piles All pile installation operations should be observed by the geotechnical engineer or their field representative experienced in the design and observation of driven piles foundations. It is essential that the field representative be present during pile driving to obtain blow count and hammer data to evaluate if the required nominal resistance has been developed. We recommend the contract include the requirement that one production pile per abutment be driven as test pile in accordance with WSDOT Standard Specifications Section (10), so that field conditions and pile driving acceptance criteria can be developed. The owner s geotechnical engineer (not the contractor) should monitor and evaluate test pile driving, and develop acceptance criteria for the remaining production piles at each abutment. 16 PROJECT NO MAY 15, 2014

21 ASPECT CONSULTING 6.4 Site Subsurface Variation and Pile Lengths Our subsurface exploration program at the Site was limited to one boring near the south abutment due to the low load rating of the existing bridge and snowy and icy road weather conditions to gain access to the north abutment location. With this, local variations of subsurface conditions along the bridge alignment should be expected. The lengths of certain piles may need to be adjusted in the field based on conditions encountered during driving. Variable pile lengths should be anticipated, and contingency provisions should be included in the contract documents to facilitate adjustment in payments to the contractor based on actual lengths of piles installed. PROJECT NO MAY 15,

22 ASPECT CONSULTING 7 References American Association of State Highway and Transportation Officials, 2012, LRFD Bridge Design Specifications, Customary U.S. Units. American Society for Testing and Materials (ASTM), 2012, American Society of Testing Materials Annual Book of Standards, Vol. 4.08, West Conshohocken, Pennsylvania. Ensoft, Inc., 2013, LPILE plus v7.02 for Windows Analysis program. International Building Code (IBC), 2012, International Building Code. Prepared by International Code Council. Idriss, I.M. and Boulanger, R.W. (2008). Soil liquefaction during earthquakes, EERI Monograph 12, Earthquake Engineering Research Institute, Oakland, California, 262 Pp Kramer, S.L., 2008, Evaluation of Liquefaction Hazards in Washington State, prepared for the Washington State Transportation Commission. United States Geological Survey (USGS), 2008, United States National Seismic Hazard Maps: United States Department of Transportation Federal Highway Administration, 2007, Driven v1.2 Analysis program. Washington State Department of Transportation (WSDOT), 2014, Standard Specifications for Road, Bridge and Municipal Construction, Document M Washington State Legislature, 2009, Washington Administrative Code (WAC), April 1, Youd, T.L. et al. (2001). Liquefaction resistance of soils: Summary report from the 1996 NCEER and 1998 NCEER/NSF workshops on evaluation of liquefaction resistance of soils, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 127(10), PROJECT NO MAY 15, 2014

23 ASPECT CONSULTING Limitations Work for this project was performed and this report prepared in accordance with generally accepted professional practices for the nature and conditions of work completed in the same or similar localities, at the time the work was performed. All reports prepared by Aspect Consulting are intended solely for the Client and apply only to the services described in the Agreement with Client. Any use or reuse by Client for purposes outside of the scope of Client s Agreement is at the sole risk of Client and without liability to Aspect Consulting. Aspect Consulting shall not be liable for any third parties use of the deliverables provided by Aspect Consulting. Aspect Consulting s original files/reports shall govern in the event of any dispute regarding the content of electronic documents furnished to others. This report and our conclusions and interpretations should not be construed as a warranty of the subsurface conditions. Experience has shown that subsurface soil and groundwater conditions can vary significantly over small distances. Inconsistent conditions can occur between explorations and may not be detected by a geotechnical study. Further geotechnical evaluations, analyses and recommendations may be necessary for the final design of this project. If there is a substantial lapse of time between the submission of this report and the start of construction, or if conditions have changed due to construction operations at or near the Site, it is recommended that this report be reviewed to determine the applicability of the conclusions and recommendations considering the changed conditions and time lapse. PROJECT NO MAY 15,

24 FIGURES

25 C e n t r a l Cr e e k S weat C r e e k R o c k C reek LOUP LOUP REPLACEMENT BRIDGE D ep u e C r e ek ^_ SITE LOCATION!!!!(! Mowich Illahee Olema Ruby Conconully Wo o l l o o moo l o o L o u p!!! HAPPY HILL Salmon Creek WINDY HILL Malott ek! TARHEEL FLAT Ophir Wakefield Cr Loup e!! POGUE F LAT Chillowist!!!! Omak Okanogan Barker Keystone Riverside Cherokee C ree k GIS Path: T:\projects_8\LoupLoupBridge_130182\Delivered\01 Site Vicinity.mxd Coordinate System: NAD 1983 StatePlane Washington North FIPS 4601 Feet Date Saved: 2/10/2014 User: ehealy Print Date: 2/10/2014 Sum m i t C r e ek i t t l e L 0 3,000 6,000 Feet! Bellingham! Port Angeles! # Seattle Sull i v anc k r e e! SITE LOCATION! Tacoma Olympia W A S H I N G T O N!( Yakima! Spokane L oup Site Location Map L o u p C r e e k Loup Loup Replacement Bridge Okanogan County, Washington C O N SU LTI N G APR-2014 PROJECT NO BY: NCS / EAH REV BY: FIGURE NO. 1

26 GIS Path: T:\projects_8\LoupLoupBridge_130182\Delivered\02 Site and Exploration Map.mxd Coordinate System: Date Saved: 4/4/2014 User: ehealy Print Date: 4/4/2014 Site and Exploration Map Loup Loup Bridge Replacement Okanogan County, Washington C O N SU LTI N G APR-2014 PROJECT NO BY: NCS / EAH REV BY: FIGURE NO. 2 Note: Site drawing provided by Nicholls Engineering,,

27 Scour Elevation = 988 feet Pile Tip Elevation (feet) Minimum Pile Tip Embedment = 952 feet Nominal Resistance (kips) Nominal Bearing (Compression) Resistance Nominal Uplift Resistance Aspect Consulting April 2014 Notes: 1) Nominal Bearing Resistance shown on this plot is unfactored and can be used with Table 4 - Resistance Factors for Driven Pile Design to determine Strength, Service, and Extreme limit state pile resistances. Figure 3 Estimated Axial Pile Nominal Resistance - Driven, Closed-End, 18-inch Diameter, Steel Pipe Pile

28 Elevation (feet) Applied P m = Deflection (inches) 1/4-inch Head Deflection, Fixed Head Condition 1/4-inch Head Deflection, Free Head Condition 2-inch Head Deflection, Fixed Head Condition 2-inch Head Deflection, Free Head Condition Aspect Consulting April 2014 Figure 4 Lateral Pile Deflection Profile Driven, Closed-End, 18-inch Diameter, Steel Pipe Pile

29 Elevation (feet) Applied P m = Shear (kips) 1/4-inch Head Deflection, Fixed Head Condition 1/4-inch Head Deflection, Free Head Condition 2-inch Head Deflection, Fixed Head Condition 2-inch Head Deflection, Free Head Condition Aspect Consulting April 2014 Figure 5 Lateral Pile Shear Resistance Profile Driven, Closed-End, 18-inch Diameter, Steel Pipe Pile

30 Elevation (feet) Applied P m = Moment (ft kips) 1/4-inch Head Deflection, Fixed Head Condition 1/4-inch Head Deflection, Free Head Condition 2-inch Head Deflection, Fixed Head Condition 2-inch Head Deflection, Free Head Condition Aspect Consulting April 2014 Figure 6 Lateral Pile Moment Profile Driven, Closed-End, 18-inch Diameter, Steel Pipe Pile

31 APPENDIX A Subsurface Explorations

32 ASPECT CONSULTING A.1 Field Exploration Program A.1.1 Geotechnical Borings On November 5, 2013, we performed a geologic reconnaissance and completed one geotechnical boring (B-1) to a depth of 61.5 feet below the existing ground surface on the south side of Loup Loup Creek, using mud-rotary auger drilling techniques. The boring was completed at the west extent of Loup Loup Canyon Road, about 25 feet from the longitudinal centerline of the new bridge. A second boring was planned on the north side of Loup Loup Creek, but the existing bridge load rating was not capable of supporting the drill rig to cross the bridge and winter weather road conditions prevented access from the road to the north. The location of the geotechnical boring is shown on Figure 2. Sampling was completed at selected depth intervals using the Standard Penetration Test (SPT) in general accordance with ASTM method D1586. This involves driving a 2-inch outside-diameter split-barrel sampler a distance of 18 inches into the soil with a 140- pound hammer free-falling from a distance of 30 inches. The number of blows for each 6-inch interval is recorded and the number of blows required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance ( N ) or blow count. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils. An Aspect Consulting representative was present throughout the field exploration program to observe the drilling procedure, assist in sampling, and to prepare descriptive logs of the exploration. Soils were classified in general accordance with ASTM D-2488 Standard Practice for Description and Identification of Soils (Visual-Manual Procedure). The summary exploration log represents our interpretation of the contents of the field logs. The stratigraphic contacts shown on the individual summary logs represent the approximate boundaries between soil types; actual transitions may be more gradual. The subsurface conditions depicted are only for the specific date and locations reported, and therefore, are not necessarily representative of other locations and times. A.1.2 Bank and Channel Soil Samples Four bulk soil samples were collected from the bank and channel of Loup Loup Creek about 25 feet upstream and 25 feet downstream of the new bridge location using hand tools. The soil samples were submitted to a geotechnical testing laboratory for grain size analysis. The grain size analysis results are shown in Appendix B. PROJECT NO MAY 15, 2014 A-1

33 (1) (1) Fine-Grained Soils - 50% or More Passes No. 200 Sieve Coarse-Grained Soils - More than 50% Retained on No. 200 Sieve Gravels - More than 50% of Coarse Fraction Retained on No. 4 Sieve (1) (1) Sands - 50% or More of Coarse Fraction Passes No. 4 Sieve Highly Organic Soils (5) (5) 15% Fines 5% Fines (5) Silts and Clays Liquid Limit Less than 50 Silts and Clays Liquid Limit 50 or More (5) 15% Fines 5% Fines GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT Well-graded gravel and gravel with sand, little to no fines Poorly-graded gravel and gravel with sand, little to no fines Silty gravel and silty gravel with sand Clayey gravel and clayey gravel with sand Well-graded sand and sand with gravel, little to no fines Poorly-graded sand and sand with gravel, little to no fines Silty sand and silty sand with gravel Clayey sand and clayey sand with gravel Silt, sandy silt, gravelly silt, silt with sand or gravel Clay of low to medium plasticity; silty, sandy, or gravelly clay, lean clay Organic clay or silt of low plasticity Elastic silt, clayey silt, silt with micaceous or diatomaceous fine sand or silt Clay of high plasticity, sandy or gravelly clay, fat clay with sand or gravel Organic clay or silt of medium to high plasticity Peat, muck and other highly organic soils Terms Describing Relative Density and Consistency Coarse- Grained Soils Fine- Grained Soils Descriptive Term Estimated Percentage Percentage by Weight Modifier <5 Trace Sampler Type 2.0" OD Split-Spoon Sampler (SPT) Bulk sample Grab Sample (1) (2) (3) Boulders Cobbles Gravel Coarse Gravel Fine Gravel Sand Coarse Sand Medium Sand Fine Sand Silt and Clay Density Very Loose Loose Medium Dense Dense Very Dense Consistency Very Soft Soft Medium Stiff Stiff Very Stiff Hard Blows/6" or portion of 6" (2) SPT blows/foot 0 to 4 4 to to to 50 >50 (2) SPT blows/foot Component Definitions Size Range and Sieve Number Larger than 12" 3" to 12" Smaller than No. 200 (0.075 mm) Symbols Sampler Type Description Continuous Push Non-Standard Sampler 0 to 2 2 to 4 4 to 8 8 to to 30 >30 3.0" OD Thin-Wall Tube Sampler (including Shelby tube) Portion not recovered Percentage by dry weight (SPT) Standard Penetration Test (ASTM D-1586) In General Accordance with Standard Practice for Description and Identification of Soils (ASTM D-2488) (4) Depth of groundwater 3" to No. 4 (4.75 mm) 3" to 3/4" 3/4" to No. 4 (4.75 mm) No. 4 (4.75 mm) to No. 200 (0.075 mm) No. 4 (4.75 mm) to No. 10 (2.00 mm) No. 10 (2.00 mm) to No. 40 (0.425 mm) No. 40 (0.425 mm) to No. 200 (0.075 mm) ATD = At time of drilling Static water level (date) Test Symbols FC = Fines Content G = Grain Size M = Moisture Content A = Atterberg Limits C = Consolidation DD = Dry Density K = Permeability Str = Shear Strength Env = Environmental PiD = Photoionization Detector Moisture Content Dry - Absence of moisture, dusty, dry to the touch Slightly Moist - Perceptible moisture Moist - Damp but no visible water Very Moist - Water visible but not free draining Wet - Visible free water, usually from below water table Classifications of soils in this report are based on visual field and/or laboratory observations, which include density/consistency, moisture condition, grain size, and plasticity estimates and should not be construed to imply field or laboratory testing unless presented herein. Visual-manual and/or laboratory classification methods of ASTM D-2487 and D-2488 were used as an identification guide for the Unified Soil Classification System. earth + water 5 to to to 49 Exploration Log Key Slightly (sandy, silty, clayey, gravelly) Sandy, silty, clayey, gravelly) Very (sandy, silty, clayey, gravelly) Grouted Transducer Cement grout surface seal Bentonite chips Grout seal Filter pack with blank casing section Screened casing or Hydrotip with filter pack End cap (5) Combined USCS symbols used for fines between 5% and 15% as estimated in General Accordance with Standard Practice for Description and Identification of Soils (ASTM D-2488) DATE: BGS = below ground surface DESIGNED BY: DRAWN BY: REVISED BY: PROJECT NO. FIGURE NO. A-1 Q:\_ACAD Standards\Standard Details\Exploration Log Key A1.dwg

34 Project Name: Location: Driller/Equipment: Loup Loup Bridge Replacement Holocene / Truck rig S-1 G Project Number Drilling Method/Hammer: Mud Rotary 3-7/8 inch bit. 140 lb, 30 inch drop, Autohammer Depth / Elevation (feet) Loup Loup Canyon Road, Okanogan, WA Borehole Completion Sample Type/ID Tests Blows/ 6" N-value Water Content % Material Type Boring Log Boring Number B-1 Ground Surface Elev Depth to Water Start/Finish Date Description Sheet 1 of /5/2013 Dense, moist, brown, sandy, GRAVEL (GP); trace silt, roadway base, poorly graded (FILL) Medium dense, very moist, brown, slightly silty, slightly gravelly, SAND (SW-SM); well-graded, fine to coarse sand, subrounded to subangular fine gravel (FILL) Depth (ft) S Loose to medium dense, very moist, brown, slightly silty, SAND (SP-SM); trace gravel, poorly graded fine to medium sand, subrounded to subangular, fine gravel (ALLUVIUM) S Medium dense, very moist, brown, slightly silty, SAND (SP-SM); trace organic mater, poorly graded, fine to medium sand, subrounded to subangular S-4 G Medium dense, wet, brown, silty, SAND (SM); trace fine gravel, well graded, fine to coarse sand, subrounded to subangular S Rock observed in S-4; blowcount may be overstated Medium dense, wet, brown, slightly gravelly, SAND (SP-SM); trace silt, well graded, fine to coarse sand, subrounded to subangular, fine gravel Color change in drilling mud - darker gray color 18 _GEOTECH BORING LOG LOGS_GINT.GPJ January 29, Sampler Type: No Recovery Standard Penetration Test (ASTM D1586) S Drilling Method: HSA: Hollow Stem Auger MR: Mud Rotary Medium dense, wet, gray, slightly silty, gravelly, SAND (SW-SM); trace silt, well graded, fine to coarse sand, subrounded to subangular, fine gravel Logged by: Approved by: Figure No. NCS HHH

35 Project Name: Location: Driller/Equipment: Loup Loup Bridge Replacement Holocene / Truck rig S Project Number Drilling Method/Hammer: Mud Rotary 3-7/8 inch bit. 140 lb, 30 inch drop, Autohammer Depth / Elevation (feet) Loup Loup Canyon Road, Okanogan, WA Borehole Completion Sample Type/ID Tests Blows/ 6" N-value Water Content % Material Type Boring Log Boring Number B-1 Ground Surface Elev Depth to Water Start/Finish Date Description Sheet 2 of /5/2013 Loose to medium dense, wet, gray, slightly gravelly, SAND (SW); trace silt, well graded, fine to coarse sand, subrounded to subangular, fine gravel. 2-inch thick organic silt lens at 25 to 25.2 feet Depth (ft) S-8 G Loose to medium dense, wet gray, slightly silty, SAND (SP-SM); with numerous organic matter and stiff organic silt stratifications 1/4 to 3/4 inch thick, poorly graded, fine to medium sand, subrounded to subangular S-9 G Loose, wet, gray, slightly silty, SAND (SP-SM); occasional stiff organic silt stratifications 1/4 to 1/2 inch thick, poorly graded, fine to medium sand Increase in drilling mud pump pressure Stiff, very moist, dark brown, organic SILT (OL); with numerous sand lens 1 to 2 inch thick S-10 A Organic Medium dense, wet, gray, slightly silty SAND (SP-SM); trace gravel, well graded, fine to medium sand, subrounded to subangular _GEOTECH BORING LOG LOGS_GINT.GPJ January 29, Sampler Type: No Recovery Standard Penetration Test (ASTM D1586) S Drilling Method: HSA: Hollow Stem Auger MR: Mud Rotary Medium dense, wet, gray, slightly silty, slightly gravelly, SAND (SP-SM); poorly graded, fine to medium sand, fine, subrounded to subangular Rough drilling action at 49.5 to 50.0 feet Logged by: Approved by: Figure No. NCS HHH

36 Project Name: Location: Driller/Equipment: 51 Loup Loup Bridge Replacement Holocene / Truck rig S Project Number Drilling Method/Hammer: Mud Rotary 3-7/8 inch bit. 140 lb, 30 inch drop, Autohammer Depth / Elevation (feet) 951 Loup Loup Canyon Road, Okanogan, WA Borehole Completion Sample Type/ID Tests Blows/ 6" N-value Water Content % Material Type Boring Log Boring Number B-1 Ground Surface Elev Depth to Water Start/Finish Date Description Sheet 3 of /5/2013 Medium dense, wet, gray, slightly silty, slightly gravelly, SAND (SP-SM); poorly graded, fine to medium sand, fine, subrounded to subangular Depth (ft) Stiff, wet, gray, very sandy, non-plastic SILT (ML); trace gravel More drilling resistance; slower advance rate, smooth drill action S-13 G S Medium dense, wet, gray, SAND (SW); trace silt, well graded, fine to coarse sand, subrounded to subangular Bottom of boring _GEOTECH BORING LOG LOGS_GINT.GPJ January 29, Sampler Type: No Recovery Standard Penetration Test (ASTM D1586) Drilling Method: HSA: Hollow Stem Auger MR: Mud Rotary Logged by: Approved by: Figure No. NCS HHH

37 APPENDIX B Laboratory Test Results

38 B.1 Geotechnical Laboratory Testing Geotechnical laboratory tests were conducted on selected soil samples collected during the field exploration program. The tests performed and the procedures followed are outlined below. Grain Size Analysis (G) Grain size analysis was analyzed in accordance with ASTM D 422 on SPT soil samples collected from soil boring B-1, and stream bank and channel grab samples. The results of the tests are presented as curves on Figures B-1 and B-9, plotting percent finer by weight versus grain size. Water Content Determination Water contents were determined in accordance with ASTM D 422 on SPT soil samples collected from soil boring B-1, and stream bank and channel grab samples in general accordance with ASTM D The results of the tests are presented on the boring log Figure A-2. Atterberg Limits Atterberg Limits (plasticity) were determined in accordance with ASTM D4318 on one fine-grained SPT soil sample (S-10) collected from soil boring B-1. The result of the test is shown on Figure B-10. Organic Content Determination Organic content determination was completed in accordance AASHTO T276 on one SPT soil sample (S-10) collect from soil boring B-1. The results of the test is shown on Figure B-11. PROJECT NO MAY 15, 2014 B-1

39

40 CSI: Construction Special Inspection MATERIALS TESTING & SPECIAL INSPECTION 104 East Ninth Street Wenatchee, WA (509) SOIL CLASSIFICATION SIEVE ANALYSIS ASTM D-422 & D-2487 CLIENT: Aspect LAB NO: PROJECT NO: DATE RCVD: 11/18/2013 PROJECT: Loup Loup Bridge DATE TESTED: 11/20/2013 CONTRACTOR: N/A SUBMITTED BY: Nick Szot SAMPLE LOCATION: B-1, S-1 SAMPLE DEPTH: SAMPLE DESC.: Well Graded Sand W/Silt (SW-SM) SIEVE SIZE (in.) SIEVE SIZE (mm) ACC. WEIGHT RETAINED (grams) PERCENT MATERIAL RETAINED PERCENT MATERIAL PASSING SPECIFICATION REQUIRED MATERIAL DESCRIPTION 4" COBBLES 3" COBBLES 2 1/2" COARSE GRAVEL 2" COARSE GRAVEL 1-1/2" COARSE GRAVEL 1" COARSE GRAVEL 3/4" COARSE GRAVEL 5/8" COARSE GRAVEL 1/2" FINE GRAVEL 3/8" FINE GRAVEL 1/4" 6.40 FINE GRAVEL No FINE GRAVEL No COARSE SAND No COARSE SAND No COARSE SAND No um MEDIUM SAND No um MEDIUM SAND No um MEDIUM SAND No um MEDIUM SAND No um FINE SAND No um FINE SAND No um FINE SAND No um FINE SAND No um FINE SAND No um SILT TOTAL PERCENT MOISTURE: 16.3% % REMARKS: TECHNICIAN: R. GILL PROJ. MGR. J.HILLS ClassSieve Rev'd

41

42 CSI: Construction Special Inspection MATERIALS TESTING & SPECIAL INSPECTION 104 East Ninth Street Wenatchee, WA (509) SOIL CLASSIFICATION SIEVE ANALYSIS ASTM D-422 & D-2487 CLIENT: Aspect LAB NO: PROJECT NO: DATE RCVD: 11/18/2013 PROJECT: Loup Loup Bridge DATE TESTED: 11/20/2013 CONTRACTOR: N/A SUBMITTED BY: Nick Szot SAMPLE LOCATION: B-1, S-4 SAMPLE DEPTH: SAMPLE DESC.: Silty Sand (SM) SIEVE SIZE (in.) SIEVE SIZE (mm) ACC. WEIGHT RETAINED (grams) PERCENT MATERIAL RETAINED PERCENT MATERIAL PASSING SPECIFICATION REQUIRED MATERIAL DESCRIPTION 4" COBBLES 3" COBBLES 2 1/2" COARSE GRAVEL 2" COARSE GRAVEL 1-1/2" COARSE GRAVEL 1" COARSE GRAVEL 3/4" COARSE GRAVEL 5/8" COARSE GRAVEL 1/2" FINE GRAVEL 3/8" FINE GRAVEL 1/4" 6.40 FINE GRAVEL No FINE GRAVEL No COARSE SAND No COARSE SAND No COARSE SAND No um MEDIUM SAND No um MEDIUM SAND No um MEDIUM SAND No um MEDIUM SAND No um FINE SAND No um FINE SAND No um FINE SAND No um FINE SAND No um FINE SAND No um SILT TOTAL PERCENT MOISTURE: 16.2% % REMARKS: TECHNICIAN: R. GILL PROJ. MGR. J.HILLS ClassSieve Rev'd

43

44 CSI: Construction Special Inspection MATERIALS TESTING & SPECIAL INSPECTION 104 East Ninth Street Wenatchee, WA (509) SOIL CLASSIFICATION SIEVE ANALYSIS ASTM D-422 & D-2487 CLIENT: Aspect LAB NO: PROJECT NO: DATE RCVD: 11/18/2013 PROJECT: Loup Loup Bridge DATE TESTED: 11/20/2013 CONTRACTOR: N/A SUBMITTED BY: Nick Szot SAMPLE LOCATION: B-1, S-8 SAMPLE DEPTH: SAMPLE DESC.: Silty Sand (SM) SIEVE SIZE (in.) SIEVE SIZE (mm) ACC. WEIGHT RETAINED (grams) PERCENT MATERIAL RETAINED PERCENT MATERIAL PASSING SPECIFICATION REQUIRED MATERIAL DESCRIPTION 4" COBBLES 3" COBBLES 2 1/2" COARSE GRAVEL 2" COARSE GRAVEL 1-1/2" COARSE GRAVEL 1" COARSE GRAVEL 3/4" COARSE GRAVEL 5/8" COARSE GRAVEL 1/2" FINE GRAVEL 3/8" FINE GRAVEL 1/4" 6.40 FINE GRAVEL No FINE GRAVEL No COARSE SAND No COARSE SAND No COARSE SAND No um MEDIUM SAND No um MEDIUM SAND No um MEDIUM SAND No um MEDIUM SAND No um FINE SAND No um FINE SAND No um FINE SAND No um FINE SAND No um FINE SAND No um SILT TOTAL PERCENT MOISTURE: 42.5% % REMARKS: Organic rich - Assume fines as ML TECHNICIAN: R. GILL PROJ. MGR. J.HILLS ClassSieve Rev'd

45