Geotechnical Engineering Services

Transcription

1 Geotechnical Engineering Services, Washington for February, 2014 Earth Science + Technology

2 Geotechnical Engineering Services Crystal Mountain Boulevard Upgrade Pierce County, Washington for Pierce County Public Works and Utilities February 21, th Avenue NE Redmond, Washington

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4 Table of Contents INTRODUCTION AND PROJECT UNDERSTANDING... 1 PURPOSE AND SCOPE OF SERVICES... 1 Task 1. Project Scoping... 1 Task 2. Field Explorations and Data Acquisition... 1 Task 3. Analyses and Reporting... 2 FIELD EXPLORATIONS AND LABORATORY TESTING... 3 Field Explorations... 3 Laboratory Testing... 3 SITE DESCRIPTION... 3 Project Location... 3 Regional Geology... 4 General... 4 Surface Conditions... 4 Subsurface Soil and Bedrock Conditions... 4 General... 4 Road Widening Area... 5 Bridge Bridge Bridge Groundwater Conditions... 6 CONCLUSIONS AND RECOMMENDATIONS... 6 General... 6 Earthquake Engineering... 7 Surface Fault Rupture... 7 Liquefaction... 8 Temporary Modular Bridge Foundation Support... 8 Bridge Foundation Support... 8 Design Criteria... 8 Slope Setbacks Bridge Retaining Walls Lateral Earth Pressures Wall Drainage Temporary Excavations and Shoring Support Temporary Dewatering Open Pumping Earthwork Excavation Considerations Clearing and Grubbing Creek Diversion Subgrade Preparation Structural Fill Materials On-site Soils Fill Placement and Compaction Criteria Permanent Soil Slopes February 21, 2014 Page i File No

5 Table of Contents (continued) Weather Considerations Sedimentation and Erosion Control PAVEMENT CONSIDERATIONS OTHER CONSIDERATIONS LIMITATIONS REFERENCES LIST OF FIGURES Figure 1. Vicinity Map Figure 2. Culvert/Bridge 1 Overview Map Figure 3. Culvert/Bridge 1 Cross Section A-A Figure 4. Culvert/Bridge 1 Cross Section B-B Figure 5. Culvert/Bridge 2 Overview Map Figure 6. Culvert/Bridge 2 Cross Section C-C Figure 7. Culvert/Bridge 2 Cross Section D-D Figure 8. Culvert/Bridge 3 Overview Map Figure 9. Culvert/Bridge 3 Cross Section E-E Figure 10. Culvert/Bridge 3 Cross Section F-F Figure 11. Longitudinal Cross Sections Figure 12. Shallow Foundation Design Soil Figure 13. Shallow Foundation Design Bedrock APPENDICES Appendix A. Field Explorations Figure A-1 Key to Exploration Logs Figure A-2 WSDOT Rock Classification Figures A-3 through A-9. Logs of Boring Appendix B. Laboratory Testing Figures B-1 and B-2 Sieve Analysis Results Figure B-3 Atterberg Limits Tests Appendix C. Report Limitations and Guidelines For Use Page ii February 21, 2014 GeoEngineers, Inc. File No

6 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington INTRODUCTION AND PROJECT UNDERSTANDING This report presents the results of our geotechnical engineering services for the proposed Crystal Mountain Boulevard Upgrade project in eastern Pierce County, Washington. The project site is shown relative to surrounding physical features on the Vicinity Map, Figure 1. The project will include design and construction of three new bridges to replace the existing culverts carrying Silver Creek beneath the boulevard, design of a mitigation for a rock slide/rock fall area along the roadway, and design of new pavement sections. GeoEngineers is also providing permitting and environmental planning support for the project team, and has also recently completed a geologic hazard evaluation, wetlands characterization and geomorphic study for the project. The location of the bridges and project components along Crystal Mountain Boulevard are shown on the Site Plans, Figures 2 through 10. Our understanding of the project is based on our site visits, meetings and calls with the County and other project team members. At this time, we understand that the County plans to construct temporary bridges to assist in replacing the existing culverts using the Acrow or a similar modular bridge system. We understand that the temporary bridge system will be about 18 feet in width, allowing for one lane of traffic across the work area. We understand that the temporary bridges can be supported on-grade on temporary concrete, timber pedestals/cribbing, or on steel plates placed on top of the existing roadway. Once the temporary bridge system is in place, the existing culverts will be removed using open cut construction below the temporary bridge system. The culverts will be replaced with three-sided permanent bridges at the base of the excavation. Roadway embankment fill will then be placed to bury the permanent bridges. After placement of each new permanent bridge and reconstruction of the road fill embankment, the temporary modular bridge section will be removed and the roadway will be restored. PURPOSE AND SCOPE OF SERVICES The purpose of our services is to evaluate subsurface conditions in the vicinity of the proposed bridges and road realignment, to provide geotechnical conclusions and recommendations for the bridges and road realignment, and to provide geologic input into rockfall mitigation options. Our scope of services includes the following tasks: Task 1. Project Scoping Coordinate with you on the scope of service for the additional services for this project. Perform initial site reconnaissance and meet drilling subcontractors on site to verify accessibility and to mark planned exploration locations for utility checks. Task 2. Field Explorations and Data Acquisition Review the existing geologic hazards report prepared for permitting. Review existing report and recommendations prepared by Golder Associates (Golder) pertaining to rock fall evaluation and mitigation. February 21, 2014 Page 1 File No

7 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington Complete a detailed geologic reconnaissance along the existing exposed rock faces along the southern portion of the roadway. Collect slope configuration data, additional measurements of discontinuity orientations and rock size data for completing rock fall analyses using program CRISP and to complete test rock falls, if possible, to help calibrate the model. Compare recommendations prepared by Golder and evaluate appropriateness based on existing conditions. Plan the Exploration Program and Obtain Permits including submitting permit applications, traffic control plans, and boring exploration plans to the County. Contact the Washington State one-call service and follow new State protocols for underground utility locate procedures. Coordinate and subcontract for Traffic Control Plans and for Traffic Control Services during drilling of the explorations within the travel lanes. Subcontract for drilling seven borings, two borings at each bridge site and one near the rock face portion of the roadway near the planned roadway widening, using sonic and rock coring drilling methods. Observe and provide geotechnical soil logging during exploration drilling, including selection of samples for sieve analysis and California Bearing Ratio (CBR) tests. Task 3. Analyses and Reporting Evaluate pertinent physical and engineering characteristics of the soils and rock based on laboratory tests performed on samples obtained from the borings. Develop recommendations for site preparation and grading, including temporary and permanent slopes, fill placement criteria, suitability of on-site soils for fill and subgrade preparation. Develop foundation support recommendations for the Acrow or modular bridge. Provide recommendations for the design of the new bridges including design parameters, subgrade preparation, foundation support and lateral soil pressures. Comment on any anticipated construction difficulties identified from the results of our site studies and from our experience on projects at similar sites. Discuss seismicity at the site and evaluate the earthquake engineering aspects of the project. Compile and evaluate data from rock slope field evaluation, including the slope configuration, orientation of discontinuities, and size of rock blocks observed or anticipated. Complete modeling of rock fall patterns using program CRISP. Evaluate alternative rock fall mitigation options, advantages and disadvantages. Prepare a draft and final interim memorandum presenting preliminary results of the rock slope mitigation evaluation. Develop recommendations for protection of the roadway from rock fall or rock slides. Page 2 February 21, 2014 GeoEngineers, Inc. File No

8 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington Provide information regarding the composition and condition of the existing roadway subgrade. Prepare a draft and final Geotechnical and Rock Stabilization Design report summarizing the results of our geotechnical engineering and geologic investigation including descriptions of roadway, surface and subsurface conditions. Prepare draft plans and specifications for stabilizing the rock slopes using the selected stabilization method(s) to be incorporated into the County s design package. Finalize our plans following receipt of comments by you. Meet with the County and/or project team up to two times to discuss findings and answer questions relating to soil and rock conditions and geotechnical and bedrock considerations. This report presents geotechnical conclusions and recommendations for the planned bridge structures and roadway realignment. A separate report is being prepared for the rockfall mitigation and rock stabilization portion of the project. FIELD EXPLORATIONS AND LABORATORY TESTING Field Explorations Subsurface conditions at the site were evaluated by drilling seven borings (B-1 through B-7) along Crystal Mountain Boulevard to depths of 17 to 69 feet. The borings were drilled on September 30 through October 7, 2013 using truck mounted sonic and rotary drilling equipment. The approximate locations each boring is shown on the Site Plans, Figures 2 through 10. A detailed description of the field exploration program and the boring logs are presented in Appendix A. Laboratory Testing Soil samples were obtained during the exploration program and taken to our laboratory for further evaluation. Selected samples were tested for the determination of moisture content, fines content, sieve analyses, Atterberg limits (plasticity characteristics), CBR, and unconfined compression strength. A description of the laboratory testing and the test results are presented in Appendix B. SITE DESCRIPTION Project Location The project is located within the Silver Creek basin in Mount Baker-Snoqualmie National Forest. Crystal Mountain Boulevard connects State Route (SR) 410 with Crystal Mountain Resort and other recreational opportunities on National Forest lands. The project traverses Sections 02, 03, 11, 12, 13 and 24 of Township 17 North and Range 10 East of the Willamette Meridian. The project features and locations are shown on the Vicinity Map, Figure 1, and Site Plans, Figures 2 through 10. February 21, 2014 Page 3 File No

9 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington Regional Geology General Based on our review of the digital compilation by Washington State Department of Natural Resources [WDNR] and the Geologic Map of the Mount Rainier Quadrangle, Washington, compiled by Schasse (1987), much of the project area is underlain by volcanic rocks. Geologic units located along the proposed roadway and in the vicinity are predominately Ohanapecosh Formation. Other geologic units that are present include: Greenwater lahar, landslide debris and alluvium. Geologic hazards present within the project limits are presented in a separate report. The surface deposits within the study area consist of the following units (from oldest to youngest): Ohanapecosh Formation (Toh/Ovc(oh)) consists of various volcanic deposits including tuffs, breccias and volcaniclastic siltstone, sandstone and conglomerate. The Ohanepecosh Formation is Oligocene in age (dated approximately 23 to 34 million years). Greenwater lahar (Qmg/Qvl(g)) is a volcanic deposit that consists of a sand matrix with rock clasts (clasts may range in size up to 30 feet). The Greenwater lahar covers a small area of the study area, within the first half mile of Mile Post (MP) 0 to 1, near boring B-7. Landslide/Older landslide debris (Qls/Qls (m)) deposits consist of rock debris, colluvium and soil deposited by mass wasting. Deposits are mapped at two locations on the west side of Silver Creek Valley, near Bridge/Culvert 1 and borings B-5 and B-6. Alluvium (Qal/Qa) consists of unconsolidated silt to gravel-sized sediment and as such, is subject to erosion. Recent alluvium is deposited locally by Silver Creek and its tributaries in the vicinity of the boulevard. Surface Conditions The Crystal Mountain Boulevard has a grade varying from about 2 to 6 percent along the project alignment. At each proposed bridge location, the road is situated on a fill embankment that varies from about 5 to about 30 feet in height. The side slopes of each fill embankment vary from about 1H:1V (horizontal to vertical) to 1.5H:1V. The sides of each embankment are vegetated with a mixture of shrubs, deciduous and conifer trees. At the proposed area where the road may be shifted, the existing roadway is situated close to an existing rock cut face along the south edge and a wide gravel shoulder is present along the north edge of the roadway. Beyond the north shoulder, the ground surface slopes steeply down to the north. Subsurface Soil and Bedrock Conditions General The roadway is situated in a narrow mountain valley, with relatively steep slopes present near portions of the road. As such, in general the road is underlain by fill, where raising grades was necessary, and by native soils deposited as the result of past lahar flows, landslides, rockfall, debris flows, and alluvial fan overflow events. In general, much of the native soils are gravels with varying amounts of silt. Large boulders were encountered in the borings and should be expected in any excavations. It was sometimes difficult to differentiate between fill and native deposits. It is Page 4 February 21, 2014 GeoEngineers, Inc. File No

10 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington likely that some of the road fill came from local sources, and thus is similar in character to the native soils. Cross sections showing typical subsurface profiles at the planned Bridge locations are presented in Figure 11. The borings were mainly completed using sonic drilling equipment as the soil conditions were anticipated to consist of mainly gravels with some boulders. Sonic drilling has the advantage that the process results in almost 100 percent retrieval of the soils encountered in a 3.5- to 4-inch core, but has the disadvantage that taking standard penetration test (SPT) samples to obtain density information is difficult and expensive. Therefore, SPT samples were only taken in a small portion of the borings completed and the densities shown on the boring logs and described below are based in large part on the ease or difficulty of drilling and our knowledge of the deposition process. Road Widening Area Boring 7 was completed in the existing gravel shoulder near the northern most portion of the existing roadway alignment. Boring 7 encountered about 7 feet of gravel with variable amounts of silt and sand. We assume that most of this material is fill, although it was difficult to differentiate between fill and native gravels. The fill/native gravels are underlain by bedrock. The bedrock consists of fresh to moderately weathered gray aphanitic basalt. This bedrock is moderately strong, in fair to poor condition, and contains close to very closely spaced fractures. Bridge 1 The invert of existing culvert 1 is at a depth of about 14 feet (at the road centerline), and we anticipate that the foundations for the new bridge will be founded at a depth of about 21 to 23 feet. Borings B-5 and B-6 were completed in the vicinity of Bridge 1. Bridge 1 is situated within an old identified landslide. Each boring was located about 40 to 45 feet from the centerline of the existing culvert. Boring B-5 was completed to a depth of 46½ feet and did not encounter bedrock. Boring B-6 was completed to a depth of 69 feet and possibly encountered bedrock at a depth of 65 feet (or could be a large boulder). Both of the borings generally encountered medium dense gravel with varying silt and sand content, although the majority of the gravels were silty. Cobbles and boulders were encountered in the gravel deposits. Boring B-5 encountered a zone of soft to medium stiff silt, organic silt, and peat from a depth of about 18 to about 38 feet. Bridge 2 The invert of existing culvert 2 is at a depth of about 24 feet (at the road centerline), and we anticipate that the foundations for the new bridge will be founded at a depth of about 28 to 30 feet. Borings B-3 and B-4 were completed in the vicinity of Bridge 2 to depths of 47 and 53½ feet, respectively. Each boring was located about 45 to 60 feet from the centerline of the culvert. Boring B-3 encountered mainly gravels with varying silt and sand content, except from a depth of about 20 to 27 feet, where medium stiff silt and medium dense silty sand was encountered. Boring B-4 encountered gravels to a depth of about 12 feet, which was underlain by medium dense silty sand to a depth of about 28 feet. The silty sand was underlain by more gravel and a large boulder. February 21, 2014 Page 5 File No

11 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington Bedrock in the vicinity of Bridge 2 was encountered at a depth of about 43 feet in boring B-3 and at a depth of 38 feet in boring B-4. Bedrock consists of greenish-gray, xenolithic, slightly weathered, moderately weak volcanicalstic rock in fair to poor condition with close to very closely spaced fractures. Some calcite growth along fractures was observed in the rock cores. Bridge 3 The invert of existing culvert 3 is at a depth of about 13 feet (at the road centerline), and we anticipate that the foundations for the new bridge will be founded on bedrock at a depth of about 18 feet. Borings B-1 and B-2 were completed in the vicinity of Bridge 1 to depths of 27 and 30 feet, respectively. The borings were located about 30 to 55 feet from the centerline of the culvert. Borings B-1 and B-2 encountered medium dense gravels with varying silt and sand content over bedrock. Bedrock was encountered at a depth of 17 to 19 feet, and consisted of greenish-gray, xenolithic, moderately weathered, moderately weak volcanicalstic rock in fair condition with moderately to very closely spaced fractures. Groundwater Conditions Groundwater depths could not be determined due to the type of drilling method used to complete the explorations. Wet soil samples were observed at depths ranging from 5 to 30 feet. We anticipate that ground water levels are influenced by the level of the water in Silver Creek and by precipitation and snowmelt coming off of the nearby mountain slopes. In general, we anticipate that water levels will likely be higher during the snow meltoff months (typically May and June) and lower during the late fall months. For design purposes, the groundwater level should be assumed to be equivalent to the water level in Silver Creek. Recommendations for temporary dewatering are provided in a subsequent section of this report. CONCLUSIONS AND RECOMMENDATIONS General Based on the results of our subsurface exploration program and our geotechnical evaluation, it is our opinion that the proposed bridges replacing the existing culverts can be successfully completed from a geotechnical perspective provided the considerations presented in this report are incorporated in the project planning and design. The key geotechnical issues for the project are summarized below: The foundations for the temporary modular bridge may be founded on a pad of structural fill or recompacted existing fill soils. The new bridge foundations may be supported on bedrock or on a pad of structural fill. If peat or organic silt is encountered at the base of the excavation (mainly a possibility for Bridge 1), the overexcavation should be extended to remove the peat/organic silt or to a minimum depth of at least 4 feet below the bottom of the foundation, whichever is less. The overexcavation Page 6 February 21, 2014 GeoEngineers, Inc. File No

12 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington should be backfilled with crushed rock placed over a geotextile fabric, as recommended in the Shallow Foundations section of this report. The scour depths are being evaluated by Northwest Hydraulic Consultants (NHC). If the overexcavation required to place the bridge foundations below the estimated scour is backfilled with material less susceptible to scour, it may be possible to reduce scour depths. This option should be discussed with NHC. Open cuts are feasible, assuming the site soils are dewatered prior to excavation. We recommend temporary slopes be inclined at 1½H:1V or flatter at the site. These slopes may need to be modified depending on the excavation depth, seepage conditions, localized sloughing, and dewatering methods utilized during construction. After temporarily containing and rerouting the stream, additional dewatering using sumps or other methods might be necessary to allow for stable open cut slopes. The above summary is presented for introductory purposes only and should be used in conjunction with the complete recommendations presented in this report. Earthquake Engineering The seismic design of the proposed improvements can be completed using the design criteria presented in the Washington State Department of Transportation (WSDOT) Geotechnical Design Manual (GDM) and the AASHTO Guide Specifications for LRFD Seismic Bridge Design. The GDM references the 2002 USGS National Seismic Hazards Mapping project for determining a peak ground (bedrock) acceleration coefficient for design. The AASHTO Guide Specifications recommend a 7 percent probability of exceedance in 75 years (nominal 1,000-year earthquake) design event for development of a design spectrum for highway bridges. Based on these criteria, we recommend the parameters for site class, seismic zone, acceleration coefficient and spectral acceleration coefficients presented in Table 1. TABLE 1. AASHTO SEISMIC PARAMETERS Site Class AASHTO Seismic Parameter Seismic Design Category (SDC) for 0.30 < SD Effective Peak Ground Acceleration Coefficient AS = FpgaPGA = (1.236)(0.282) Design Spectral Acceleration Coefficient at 0.2 Second period SDS = FaSs = (1.286)(0.642) Design Spectral Acceleration Coefficient at 1.0 Second period SD1 = FvS1 = (1.98)(0.208) Recommended Value D C Surface Fault Rupture Based on our knowledge of regional geology in the vicinity of the site, distance to known active faults, and the substantial thickness of glacial and postglacial sediments beneath the site, we conclude that the potential for surface fault rupture is remote. February 21, 2014 Page 7 File No

13 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington Liquefaction Liquefaction is a phenomenon where soils experience a rapid loss of internal strength as pore water pressures increase in response to strong ground shaking. The increased pore water pressure may temporarily meet or exceed soil overburden pressures to produce conditions that allow soil and water to flow, deform, or erupt from the ground surface. Ground settlement, lateral spreading and/or sand boils may result from soil liquefaction. Structures supported on or within liquefied soils may suffer foundation settlement or lateral movement that can be damaging to the structures. We did not obtain enough SPT data to complete a liquefaction analyses. However, based on the gravelly nature of the soils encountered and the limited SPT testing, we estimate that liquefaction induced settlement could be on the order of about 1 to 2 inches at Bridges 1 and 2. Liquefaction should not occur at Bridge 3 as this structure will be founded on bedrock. The magnitude of liquefaction-induced ground settlement will vary as a function of the characteristics of the earthquake (earthquake magnitude, location, duration and intensity) and the groundwater conditions at the time of the earthquake. Temporary Modular Bridge Foundation Support Based on our conversations with Pierce County, we understand that the foundations for the temporary modular bridge will likely be about 5 to 6 feet deeper than the existing road surface to allow the temporary bridge deck elevation to be close to that of the existing road surface. Based on soils observed in our explorations located near each existing culvert, we anticipate that the excavations for the temporary bridge foundations will expose fill and native medium dense gravels with varying amounts of silt and sand. We recommend that the upper 12 inches of the exposed gravels be compacted to meet the requirements for structural fill presented under Earthwork. If the exposed soils are too wet to be compacted correctly, we recommend that the foundations for the temporary bridge be supported on a 2-foot-thick pad of 1¼-minus crushed rock or 2- to 4-inch quarry spalls to provide a stable base and uniform support. For this support condition, an allowable bearing pressure of 5,000 pounds per square foot (psf) may be used for design of the temporary bridge. This bearing pressure assumes that the face of the footing is situated a minimum of 5 feet from any slopes and far enough from slopes such that a 1H:1V line projected downward from the footing does not intersect the face of the slope. For temporary foundations supported as recommended above, we estimate that the settlement of the foundations will be on the order of 1 to 1½ inches. Differential settlement over a distance of about 20 feet should not exceed about ½ inch. Bridge Foundation Support Design Criteria Based on soils observed in our explorations located near each existing culvert, we anticipate that native medium dense silty gravels or bedrock will likely be present at the base of the excavation, depending on whether the excavation extends to bedrock or not. In the vicinity of Bridge 1, variable soils will likely be encountered, and it is possible that soft to medium stiff silt is present for at least the southeast side of the bridge. We recommend that the bridge foundations be supported on either bedrock or a 2-foot-thick pad of 1¼-minus crushed rock or 2- to 4-inch quarry spalls to Page 8 February 21, 2014 GeoEngineers, Inc. File No

14 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington provide a stable base and uniform support for the bridge. The crushed rock should be compacted as described below in the Earthwork section of this report. Where a portion of the foundation will be on bedrock and a portion on soil, we recommend that the bedrock be overexcavated two feet and the pad of crushed rock be placed over the bedrock surface. The purpose of the bedrock overexcavation and crushed rock replacement is to avoid abrupt differential settlement at the transition between bedrock and soil foundation support. The foundation should not bear directly on the bedrock unless the entire footing is founded on bedrock. If peat or organic silt is present at the bottom of the excavation, the excavation should be deepened to remove the peat/organic silt or to a minimum of 4 feet below the bottom of the foundation, whichever is less. A nonwoven geotextile (Mirafi 600X or equivalent) should be placed across the bottom of the excavation prior to placing the crushed rock or quarry spalls if peat/organic silt is present at the bottom of the excavation. A nonwoven geotextile may also be needed is silt or loose sand is present. The crushed rock or quarry spalls should be compacted, tamped or rolled to the extent possible. Our estimated bearing capacity recommendations for the bridge foundations are presented on Figures 12 and 13. The figures provide bearing capacity versus footing width for Service, Strength and Extreme Limit loading states (LRFD methodology). Figure 12 presents the design recommendations for footings founded on a 2-foot-thick pad of crushed rock or quarry spalls. Figure 13 presents bearing capacity for footings founded on bedrock. As shown on Figure 12, the service limit state assumes a settlement of 1 inch. For the south side of Bridge 1 where soft silt/organic silt may be left in place below the footing, we estimate that the settlements for this footing could be higher, on the order of up to 2 inches, assuming a footing that is 40 feet long, 8 feet wide, and with a long term load of 4 kips per square foot (ksf). The foundation subgrade conditions should be evaluated by the GeoEngineers prior to placement of forms and rebar to confirm the conditions are consistent with the recommendations presented in this report. If the subgrade soils are disturbed during excavation or observed to be loose, it may be necessary to moisture condition and re-compact the existing fill exposed at the footing subgrade elevation prior to the placement of rebar and forms. If the foundations are founded on bedrock, the rock surface should be cleaned prior to forming the footing. Any significant fractures wider than 6 inches should be cleaned to a minimum depth of 3 feet and filled with dental concrete prior to placing forms and rebar. We recommend the resistance factors presented in Table 2 be used when evaluating the three limit states for the bridge foundations. The bearing capacity charts presented on Figures 12 and 13 incorporate the appropriate resistance factors. February 21, 2014 Page 9 File No

15 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington TABLE 2. LRFD SHALLOW FOUNDATION RESISTANCE FACTORS Limit State Shear Resistance to Sliding Resistance Factor Bearing Passive Pressure Resistance to Sliding Strength Service Extreme Slope Setbacks The existing fill and native soil embankments on the downstream side of the roadway vary from about 1H:1V to 3H:1V. We anticipate that the bridge foundations will be placed some distance from the existing downstream slopes, but the exact position of the bridge foundations has not yet been finalized. The minimum embedment depth for bridge foundations founded on sloping ground should be provided as described in Table 3. In addition, the minimum embedment depth should be provided below a theoretical 4-foot-wide horizontal bench that extends from the face of the bridge foundation and intersects the sloping ground in front of the wall. TABLE 3. MINIMUM EMBEDMENT DEPTHS FOR WALLS ON SLOPING GROUND Slope in Front of Wall Minimum Embedment Depth (feet) 1 3H:1V 2H:1V H/10 or 2 feet, whichever is greater H/7 or 2 feet, whichever is greater Notes: 1 H equals the retained abutment wall height Bridge Retaining Walls Lateral Earth Pressures The bridge retaining walls should be designed using the WSDOT LRFD approach in accordance with the criteria of the WSDOT GDM in conjunction with the 2012 AASHTO LRFD Bridge Design Specifications. We recommend the abutment walls should be designed using the parameters shown in Table 4. These pressures assume that the walls are backfilled as described in the Earthwork section of this report. TABLE 4. LATERAL EARTH PRESSURES AND SOIL PARAMETERS FOR BRIDGE ABUTMENT WALLS Parameter Backfill and Foundation Soil Unit Weight, Value 135 pcf Backfill and Foundation Soil Friction Angle, 36 Active Earth Pressure Coefficient, Ka 0.26 Active Earth Pressure 1 35 pcf Passive Earth Pressure Coefficient, Kp 3.85 Passive Earth Pressure 1 Unfactored Level Toe Slope 280 pcf Seismic Earth Pressure Coefficient Ke 0.10 Page 10 February 21, 2014 GeoEngineers, Inc. File No

16 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington Seismic Earth Pressure 2,3 Traffic Surcharge Pressure 3 Parameter Value 7H psf 65 psf Concrete Wall Foundation Coefficient of Sliding Unfactored 0.72 Notes: 1 Equivalent Fluid Density triangular pressure distribution level ground conditions behind wall 2 H equals the retained wall height 3 Rectangular pressure distribution pcf pounds per cubic foot psf pounds per square foot Where large surcharge loads (such as from heavy trucks, cranes or other construction equipment) are anticipated in close proximity to the retaining walls, the walls should also be designed to accommodate the additional lateral pressures resulting from these concentrated loads. If soils adjacent to footings are disturbed during construction, the disturbed soils must be recompacted; otherwise, the lateral passive resistance value must be reduced. Wall Drainage Positive drainage should be provided behind the walls to prevent the buildup of hydrostatic pressures behind the wall. Positive drainage should be provided by backfilling the wall with a minimum 2-foot zone of gravel backfill for walls (WSDOT Standard Specifications Section (2)) and installing a perforated drainpipe with a minimum diameter of 4 inches at the base of the wall enveloped within a minimum thickness of 6 inches of gravel backfill for drains (WSDOT Standard Specifications Section (4)). An alternative to a drainpipe is to install weep holes in accordance with the WSDOT Standard Plans and WSDOT Standard Specifications Section (21). The weep holes should be positioned no lower than the estimated 100-year flood level of the creek. We recommend using either heavy-wall pipe (SDR-35) or rigid corrugated polyethylene pipe (ADS N-12, or equivalent) for wall drainage collector pipes. We recommend against using flexible tubing for wall drainpipe. The pipes should be laid with a minimum slope of ½ percent and discharge into the creek downslope of the structure. The pipe installations should include cleanouts to allow for future maintenance. Temporary Excavations and Shoring Support Shoring and temporary slope inclinations must conform to the provisions of Title 296 Washington Administrative Code (WAC), Part N, Excavation, Trenching and Shoring. The soils encountered at the site are classified as Type C soil in accordance with the provisions of Title WAC, Part N, Excavation, Trenching, and Shoring. Regardless of the soil type encountered in the excavation, shoring, trench boxes or sloped sidewalls will be required under Washington Industrial Safety and Health Act (WISHA). The contract documents should specify that the contractor is responsible for selecting excavation and dewatering methods, monitoring the excavations for safety and providing shoring, as required, to protect personnel and structures. February 21, 2014 Page 11 File No

17 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington In general, temporary cut slopes should be inclined no steeper than about 1½H:1V above the groundwater table. This guideline assumes that all surface loads are kept at a minimum distance of at least 5 feet away from the top of the slope and that significant seepage is not present on the slope face. In our opinion, any excavations below the water table will be very unstable and will either require temporary shoring or dewatering, or both, to complete the excavations successfully. Even with dewatering, some sloughing and raveling of the temporary slopes should be expected. For open cuts at the site we recommend that: Construction traffic, equipment, stockpiles or building supplies not be allowed within a distance of 5 feet from the top of the cuts. Exposed soil along the slopes be protected from surface erosion using waterproof tarps or plastic sheeting. Surface water is diverted away from the open excavations. The general condition of the slopes be observed periodically by a geotechnical engineer to confirm adequate stability. If temporary cut slopes experience excessive sloughing or raveling during construction, it may become necessary to modify the cut slopes to maintain safe working conditions and protect adjacent facilities or structures. Slopes experiencing excessive sloughing or raveling can be flattened, supported with shoring, or additional dewatering can be provided if the poor slope performance is related to groundwater seepage. Excavations deeper than 3 feet should be shored or laid back at a stable slope if workers are required to enter. Below the groundwater table, caving should be anticipated and thus shoring and/or dewatering will be required. Because of the diversity of available shoring systems and construction techniques, the design of temporary shoring is most appropriately left up to the contractor proposing to complete the installation. However, we recommend that the shoring be designed by a Professional Engineer (PE) licensed in the State of Washington, and that the PE-stamped shoring plans and calculations be submitted to Pierce County and the Engineer for review prior to construction. The following paragraphs present general recommendations for the type of shoring system and design parameters that we conclude are appropriate for the subsurface conditions at the project. We anticipate that most of the excavation will be completed using open cut slopes. However, if environmental or other constraints require temporary shoring, we anticipate that the temporary shoring would consist of either sheet piles or soldier pile walls either by drilling or driving H piles. The lateral soil pressures acting on temporary supports will depend on the nature and density of the soil behind the wall, the inclination of the ground surface behind the wall, and the groundwater level. For walls that are free to yield at the top at least one thousandth of the height of the wall (i.e., wall height times 0.001), soil pressures will be less than if movement is restrained. The design of temporary shoring should allow for lateral pressures exerted by the adjacent soil, and for surcharge loads resulting from structures, traffic, construction equipment, temporary stockpiles adjacent to the excavation, etc. Lateral load resistance can be mobilized through the use of braces, tiebacks, anchor blocks and passive pressures on members that extend below the bottom of the excavation. Temporary shoring used to support trench excavations typically uses internal bracing such as hydraulic shoring or trench boxes. Page 12 February 21, 2014 GeoEngineers, Inc. File No

18 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington We recommend that temporary yielding walls retaining native soils be designed using an equivalent fluid density of 35 pounds per cubic foot (pcf), for horizontal ground surfaces. For non-yielding (i.e., braced) systems, we recommend that the shoring be designed for a uniform lateral pressure of 26*H in psf, where H is the depth of the planned excavation in feet below a level ground surface. These values assume that the ground behind the shoring has been dewatered such that the ground water table is at least 2 feet below the base of the excavation. Temporary dewatering recommendations are discussed in a subsequent section of this report. The above lateral soil pressures do not include traffic, structure or construction surcharges that should be added separately, if appropriate. Shoring should be designed for a traffic influence equal to a uniform lateral pressure of 65 psf acting over the depth of the trench. More conservative pressure values should be used if the designer deems them appropriate. The soil pressure available to resist lateral loads against shoring is a function of the passive resistance that can develop on the face of below-grade elements of the shoring as those elements move horizontally into the soil. The allowable passive resistance on the face of embedded shoring elements may be computed using an equivalent fluid density of 280 pcf for native soils. These passive equivalent fluid density values do not include a factor of safety; an appropriate factor of safety should be used in the design of shoring. Temporary Dewatering The purpose of this report section is to present geotechnical and hydrogeological data that will influence temporary construction dewatering and to describe in general terms various types of dewatering techniques that may be feasible at the site. Detailed dewatering designs for construction are not within our scope of services. Groundwater was observed during our subsurface explorations at depths ranging from about 5 to 30 feet below the ground surface. Based on the soil conditions and our experience in the area, we expect that groundwater is influenced by the level of the water in Silver Creek and by precipitation and snowmelt coming off of the nearby mountain slopes. We anticipate that the majority of soils exposed in the excavations will consist of silty gravels. However, cleaner layers of gravel or sand might be encountered. If present, these cleaner layers could potentially have a higher groundwater flow. Assuming the creek is properly tightlined around the project area, we anticipate that most of the groundwater encountered in the excavations can be controlled by open pumping using sump pumps. However, if cleaner zones of gravel or sand are encountered, additional dewatering efforts using well points might be necessary. The level of effort required for dewatering will depend to a great extent on the time of year during which construction is accomplished and the extent to which all of the creek flow is successfully diverted around the excavation. Less seepage into the work areas should be expected if construction is accomplished in the late summer or early fall months, and correspondingly, more seepage should be expected during the wetter periods of the year. We recommend that construction be completed in the late summer or early fall months when the creek flows are typically at their lowest. February 21, 2014 Page 13 File No

19 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington If well points are necessary, we recommend that the design of the dewatering system be performed by an experienced dewatering specialist who is a PE or a Licensed Hydrogeologist in the State of Washington. The contractor should be required to submit the proposed dewatering system design and plan layout to Pierce County and the Engineer for review and comment prior to beginning construction. Open Pumping This dewatering method involves removing water that has seeped into the excavation by pumping from a sump that has been excavated at one end of the excavation or trench. Drainage ditches that are connected to the sump are typically excavated along the sidewalls at the base of the excavation or trench. The excavation for the sump and the drainage ditches should be backfilled with gravel or crushed rock to reduce the amount of erosion and associated sediment in the water pumped from the sump. In our experience, a slotted casing or perforated 55-gallon drum that is installed in the sump backfill provides a suitable housing for a submersible pump. The amount of water removed from the excavation by open pumping should be minimized because of high turbidity levels. Temporary storage of dewatering effluent from the sumps in a settlement tank or basin may be required to meet discharge permit requirements and reduce sediment content prior to discharging the water to surface water courses. Earthwork Excavation Considerations Fill and native soils, mainly consisting of gravel with varying amounts of sand and silt, were observed in the explorations. Sands and silts may also be encountered in portions of the excavations. Cobbles and large boulders were also encountered and should be expected in the excavations. We anticipate that these soils can be excavated with conventional excavation equipment, such as trackhoes or dozers. We anticipate that the excavation for Bridge 3 will extend to bedrock. We anticipate that portions of the bedrock can be removed using conventional equipment such as pneumatic hammers, large excavators, and dozers with rippers. However, portions of the bedrock will likely be difficult to excavate with conventional equipment and may require mechanical excavation (drilling and splitting) with rock tools. We recommend that the contractor be prepared to use drilling and splitting methods to accomplish rock excavation to the proposed depths. Clearing and Grubbing The existing ground surface along the project alignment is typically vegetated or paved as discussed in the Surface Conditions section of this report. Embankment areas covered with vegetation should be cleared and grubbed in accordance with Section 2-01 of the WSDOT Standard Specifications. Creek Diversion The creek should be diverted into a tight line going around the excavation such that creek water does not enter the excavation during construction. Page 14 February 21, 2014 GeoEngineers, Inc. File No

20 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington Subgrade Preparation Prior to placing new fill, subbase or base course materials, subgrade areas should be proof-rolled to locate areas of loose, soft or pumping soils. Proof-rolling can be completed using a piece of heavy tire-mounted equipment or a loaded dump truck. If proof-rolling cannot be completed due to weather or site constraints, the subgrade areas should be evaluated by probing with a steel probe rod. If soft or pumping soils are observed, such unsuitable subgrade soils should be recompacted or overexcavated and replaced. The depth of overexcavation should be determined by GeoEngineers. If deep pockets of soft or pumping soils are encountered, it may be possible to limit the depth of overexcavation by placing a Geotextile for Separation or Soil Stabilization (WSDOT Standard Specification ) on the overexcavated subgrade and covering the geotextile with structural fill. We recommend using the specified woven fabric for soil stabilization. The geotextile will provide additional support by bridging over the soft material, and will help reduce fines contamination into the structural fill. The need for geotextile fabric and overexcavation should be evaluated by GeoEngineers. GeoEngineers should monitor the subgrade preparation operations to help determine the depth of removal of soft or pumping soils, and to evaluate whether subgrade disturbance or progressive deterioration is occurring. Subgrade disturbance or deterioration could occur if the subgrade is wet and cannot be dried. If the subgrade deteriorates during proof-rolling or compaction, it may become necessary to modify the proof-rolling or compaction criteria or methods. Structural Fill Materials Materials used to construct roadways, placed to support retaining structures or foundations, or placed behind retaining structures is classified as structural fill for the purpose of this report. Structural fill material quality varies depending upon its use, as described below: 1. As a minimum, structural fill placed to construct embankments and roadways and to backfill utility trenches should meet the criteria for common borrow, WSDOT (3). Common borrow will be suitable for use as structural fill during dry weather conditions only. If structural fill is placed during wet weather, the structural fill should consist of gravel borrow, WSDOT (1). 2. Structural fill placed below the new bridge foundations should consist of 1¼-minus crushed rock, WSDOT (3) or 2- to 4-inch quarry spalls, WSDOT Structural backfill for walls should meet the criteria for gravel backfill for walls, WSDOT (2) for a zone at least 2 feet from the back of the wall. 4. Structural fill placed to surround collector pipe (drain rock) should meet the criteria for gravel backfill for drains, WSDOT (4). 5. Structural fill placed as crushed surfacing base course below pavements should conform to WSDOT (3). February 21, 2014 Page 15 File No

21 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington On-site Soils The soils observed in the explorations generally contain a high percentage of fines (silt and clay) and are moisture-sensitive. Some of the on-site soils may meet the criteria for common borrow and may be suitable for use during dry weather construction only, provided the soil has a moisture content near optimum or can be stockpiled and drained to dry the soils. Fine-grained soils (silt and clay) do not meet the criteria for common borrow and should not be used. Organic-rich soils (peat and organic silt) are unsuitable for use as structural fill. Fill Placement and Compaction Criteria Structural fill should be mechanically compacted to a firm, non-yielding condition. Structural fill should be placed in loose lifts not exceeding 1 foot in thickness. Each lift should be conditioned to the proper moisture content and compacted to the specified density before placing subsequent lifts. Structural fill should be compacted to the following criteria: 1. Structural fill placed behind retaining walls should be compacted to at least 90 percent of the maximum dry density (MDD) in general accordance with ASTM D Care should be taken when compacting fill near the face of retaining walls to avoid overcompaction and hence overstressing the walls. 2. Structural fill in embankment and new pavement areas, including utility trench backfill, should be compacted to 90 percent of the MDD (ASTM D 1557), except that the upper 2 feet of fill below final subgrade should be compacted to 95 percent of the MDD (ASTM D 1557). 3. Structural fill placed below foundations should be compacted to 95 percent of the MDD (ASTM D 1557). 4. Structural fill placed as crushed rock base course below pavements should be compacted to 95 percent of the MDD (ASTM D 1557). We recommend that a representative of GeoEngineers be present during proof-rolling and/or probing of the exposed subgrade and pavement subgrade soils, and during placement of structural fill. GeoEngineers will evaluate the adequacy of the subgrade soils and identify areas needing further work, perform in-place moisture-density tests in the fill to evaluate whether the work is being done in accordance with the compaction specifications, and advise on any modifications to procedure that may be appropriate for the prevailing conditions. Permanent Soil Slopes We recommend that permanent soil slopes, either completed using cuts or fills, be constructed no steeper than 2H:1V. To achieve uniform compaction on fill slopes, we recommend the slope be overbuilt approximately 2 feet and subsequently cut back to expose properly compacted fill. If 2H:1V side slopes will extend too close to the stream, permanent slopes of up to 1½H:1V may be used to help blend into the existing slopes. For permanent slopes constructed at inclinations between 2H:1V and 1½H:1V, we recommend that the outer 15 feet of the embankment fill consist of gravel borrow per WSDOT (1) and be compacted to at least 95 percent of the MDD (ASTM D 1557). Page 16 February 21, 2014 GeoEngineers, Inc. File No

22 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington Weather Considerations The on-site soils generally contain a high percentage of fines (silt and clay) and are moisture-sensitive. When the moisture content of these soils is more than a few percent above the optimum moisture content, these soils become muddy and unstable, operation of equipment on these soils will be difficult, and it will be difficult or impossible to meet the required compaction criteria. Additionally, disturbance of near-surface soils should be expected if earthwork is completed during periods of wet weather. The contractor will need to take precautions to protect the subgrade during periods of wet weather. The wet weather season in western Washington generally begins in October and continues through May; however, periods of wet weather may occur during any month of the year. The optimum earthwork period for these types of soils is typically June through September. If wet weather earthwork is unavoidable, we recommend that: The ground surface in and around the work area should be sloped so that surface water is directed away from the work area. The ground surface should be graded such that areas of ponded water do not develop. The contractor should take measures to prevent surface water from collecting in excavations and trenches. Measures should be implemented to remove surface water from the work area. Erosion control techniques should be implemented to prevent sediment from leaving the site. Earthwork activities should not take place during periods of heavy precipitation. Slopes with exposed soils should be covered with plastic sheeting. The contractor should take necessary measures to prevent on-site soils and soils to be used as fill from becoming wet or unstable. These measures may include the use of plastic sheeting, sumps with pumps, and grading. The site soils should not be left uncompacted and exposed to moisture. Sealing the surficial soils by rolling with a smooth-drum roller prior to periods of precipitation will help reduce the extent that these soils become wet or unstable. Construction activities should be scheduled so that the length of time that soils are left exposed to moisture is reduced to the extent practical. Sedimentation and Erosion Control In our opinion, the erosion potential of the undisturbed on-site soils is low to moderate as most of the adjacent areas are well vegetated. The amount and potential impacts of erosion are in part a function of the time of year construction occurs. Wet weather construction will increase the amount and extent of erosion. We expect that exposed soils will have moderate erosion potential during wet weather. It will therefore be necessary to put in place effective erosion controls during and after construction. These should include proper control of surface water runoff to prevent uncontrolled, concentrated surface water runoff over slope areas and reducing the time of exposure in the areas stripped during construction through prompt re-vegetation. Effective erosion and sedimentation control during construction may consist of interceptor swales and silt fences to prevent water from flowing off site. Because the runoff is likely to be silty, we February 21, 2014 Page 17 File No

23 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington recommend that the collected water be passed through a temporary desilting facility prior to discharging the water into the stormwater collection system. Completion of initial clearing and grading activities during the drier months and limiting the disturbance of the existing ground surface and vegetation where possible will also reduce the risks of erosion. Material stockpiles should be covered during wet weather to prevent erosion and soil loss. All areas disturbed during construction should be seeded and planted as soon as practical to reduce the potential for erosion. Erosion and sedimentation control measures should be installed and maintained in accordance with applicable regulatory standards. PAVEMENT CONSIDERATIONS CBR testing was originally planned as a part of this study. However, the CBR test requires that all material larger than ¾-inch-diameter be removed. The existing fill soils underlying the pavement are similar in character to the majority of native soils and generally consist of gravels with a large percentage of material greater than ¾ inch in diameter. Due the gravelly nature of the soils, only one CBR test was completed for this study. The results of our CBR test indicate a CBR of about 18 for a MDD of 91 percent and a CBR of 30 for a MDD of 96 percent. Based on the gravelly nature of the soils, the limited CBR testing, and our experience, we recommend using an average CBR value of 25 for design of the new pavements. This CBR value corresponds to a resilient subgrade Modulus (Mr) value of 17,500 pounds per square inch (psi). This value assumes that the pavement subgrade is prepared as discussed above under Earthwork and the upper 1 foot of subgrade soils is compacted to at least 95 percent of the MDD in general accordance with ASTM D OTHER CONSIDERATIONS We understand that replacement of the existing culverts may result in future downcutting of portions of the stream bed due to improved water conveyance with the new bridge structures. Where the stream is currently at or near the toe of the existing or new embankment fill, this might result in erosion along the embankment toe. We recommend that erosion protection measures be included along the existing embankment toes if deemed necessary by the hydraulic studies. LIMITATIONS We have prepared this report for the exclusive use of Pierce County and their authorized agents for the proposed Crystal Mountain Boulevard Upgrade project. The data should be provided to prospective contractors for their bidding or estimating purposes, but our report and interpretations should not be construed as a warranty of the subsurface conditions. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. No warranty or other conditions, express or implied, should be understood. Page 18 February 21, 2014 GeoEngineers, Inc. File No

24 CRYSTAL MOUNTAIN BOULEVARD UPGRADE Pierce County, Washington Any electronic form, facsimile or hard copy of the original document ( , text, table, and/or figure), if provided, and any attachments are only a copy of the original document. The original document is stored by GeoEngineers and will serve as the official document of record. Please refer to Appendix C titled Report Limitations and Guidelines for Use for additional information pertaining to use of this report. REFERENCES American Association of State Highway and Transportation Officials, LRFD Bridge Design Specifications, 2013 Interim Revisions to the 6 th Edition, Schasse, H.W., 1987, Geologic Map of the Mount Rainier Quadrangle, Washington: Washington Department of Geology and Earth Resources, Open-file report, 87-16, scale 1:100,000. United States Geological Survey, Earthquake Hazards Program, Interpolated Probabilistic Ground Motion for the Conterminous 48 States by Latitude Longitude, 2002 Data. United States Geological Survey, AASHTO Seismic Design Parameters CD, USGSSEIS-1-CD, U.S. Geological Survey, Seismic Design Maps and Tools, U.S. Seismic Design Maps. accessed December 31, Washington State Department of Ecology, 2005 Stormwater Management Manual for Western Washington: Volume II Hydrologic Analysis and Flow Control Design/BMPs. Washington State Department of Ecology, 2011 Draft Stormwater Management Manual for Western Washington. Washington State Department of Transportation, Design Manual M , July Washington State Department of Transportation, Geotechnical Design Manual, M , October Washington Administrative Code, Title 296, Part N, Excavation, Trenching and Shoring. Washington State Department of Transportation, 2012, Standard Specifications for Road, Bridge and Municipal Construction. February 21, 2014 Page 19 File No

25 Type Name of Services Here Name of Project Here for Type Client Name Here Type Date of Report Here Earth Science + Technology

26 Road Realignment! Office: Redmond Path: \\red\projects\0\ \gis\mxd\ _f1_vicinitymap.mxd Map Revised: 02 January 2014 glohrmeyer Olympia!^ W a s h i n g t o n Project Site 82 Crystal Mountain Blvd. Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. can not guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. 3. It is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without permission. Data Sources: ESRI Data & Maps Projection: WGS 1984 Web Mercator Auxiliary Sphere Culvert 1 "S "S Culvert 2 "S Culvert 3 Sources: Esri, DeLorme, NAVTEQ, TomTom, Intermap, ipc, USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong), and the GIS User Community µ Miles Vicinity Map Crystal Mountain Boulevard Upgrade Pierce County, Washington Figure 1

27 MP 3.3 Office: SEA Path: \\tac\projects\0\ \gis\mxd\geoengineers\ _x-sections_a-a'_overviewmap.mxd Map Revised: 05 February 2014 maugust Data Source: Projection: NAD 1983 StatePlane Washington South FIPS 4602 Feet Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Legend A B Cross-section Location Area of Potential Effect (APE) A' G!0 B-6 B-5 Culvert 1!0 Wetland Boundary Road Centerline Flow Direction (Silver Creek) G' Proposed Roadway Overlay/Rehabilitation MP 3.4!0 B' Estimated Wetland Boundary Approximate Proposed Boring Location OHWM Culvert MP 3.5 µ Feet Culvert/Bridge 1 Overview Map Crystal Mountain Boulevard Upgrade Pierce County, Washington Figure 2

28 A!0!0 B-6 A' Office: SEA Path: \\tac\projects\0\ \gis\mxd\geoengineers\ _x-sections_11x17l_a-a'.mxd Map Revised: 13 January 2014 maugust Feet Feet Data Source: 3,795 3,790 3,785 3,780 3,775 3,770 3,765 3,760 3, Projection: NAD 1983 StatePlane Washington South FIPS 4602 Feet Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. 60 APE (west) SR A - A' A- A' Roadway Centerline Roadway Feet Feet 220 Culvert 1 OHWM Stream OHWM APE (east) µ Feet Culvert/Bridge 1 Cross Section A - A' Crystal Mountain Boulevard Upgrade Pierce County, Washington Figure 3

29 Culvert 1 B B'!0!0 B-5 Office: SEA Path: \\tac\projects\0\ \gis\mxd\geoengineers\ _x-sections_11x17l_b-b'.mxd Map Revised: 13 January 2014 maugust Feet Feet Data Source: 3,780 3,770 3, Projection: NAD 1983 StatePlane Washington South FIPS 4602 Feet Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. 60 APE (west) SR OHWM Stream 140 OHWM 160 Wetland Roadway B - B' B - B' Centerline Feet Feet Roadway MP µ Feet APE (east) Culvert/Bridge 1 Cross Section B - B' 400 Crystal Mountain Boulevard Upgrade Pierce County, Washington Figure 4

30 MP 4.6 Office: SEA Path: \\tac\projects\0\ \gis\mxd\geoengineers\ _x-sections_c-c'_overviewmap.mxd Map Revised: 06 February 2014 maugust Data Source: Projection: NAD 1983 StatePlane Washington South FIPS 4602 Feet Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Legend C D Cross-section Location Area of Potential Effect (APE) C' H!0 B-4 Culvert 2 B-3!0 Wetland Boundary Road Centerline H' MP 4.7 Flow Direction (Silver Creek) Proposed Roadway Overlay/Rehabilitation!0 D' Estimated Wetland Boundary Approximate Proposed Boring Location OHWM Culvert µ Feet Culvert/Bridge 2 Overview Map Crystal Mountain Boulevard Upgrade Pierce County, Washington Figure 5

31 C C'!0!0 B-4 Office: SEA Path: \\tac\projects\0\ \gis\mxd\geoengineers\ _x-sections_11x17l_c-c'.mxd Map Revised: 13 January 2014 maugust Data Source: Feet 3,950 3,945 3,940 3,935 3,930 3,925 3,920 3,915 3, Projection: NAD 1983 StatePlane Washington South FIPS 4602 Feet Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. OHWM APE (west) 60 OHWM SR Culvert 2 Stream Roadway C - C' Centerline Roadway Feet µ Feet APE (east) Culvert/Bridge 2 Cross Section C - C' Crystal Mountain Boulevard Upgrade Pierce County, Washington Figure 6

32 Culvert 2 D D' Office: SEA Path: \\tac\projects\0\ \gis\mxd\geoengineers\ _x-sections_11x17l_d-d'.mxd Map Revised: 13 January 2014 maugust Feet 3,950 3,945 3,940 3,935 3,930 3,925 3,920 0 Data Source: Projection: NAD 1983 StatePlane Washington South FIPS 4602 Feet Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. 80 APE (west) SR Roadway 200!0!0 B-3 D - D' Centerline Roadway 220 Feet Source: E OHWM Stream OHWM APE (east) µ Feet Culvert/Bridge 2 Cross Section D - D' 440 Crystal Mountain Boulevard Upgrade Pierce County, Washington Figure 7

33 MP 5.8 Office: SEA Path: \\tac\projects\0\ \gis\mxd\geoengineers\ _x-sections_e-e'_overviewmap.mxd Map Revised: 06 February 2014 maugust Data Source: Projection: NAD 1983 StatePlane Washington South FIPS 4602 Feet Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Legend E F Cross-section Location Area of Potential Effect (APE) Culvert 3 I!0 B-2 B-1!0 I' MP 5.9 Wetland Boundary Road Centerline Flow Direction (Silver Creek) Proposed Roadway Overlay/Rehabilitation!0 E' F' Estimated Wetland Boundary Approximate Proposed Boring Location OHWM Culvert µ Feet Culvert/Bridge 3 Overview Map Crystal Mountain Boulevard Upgrade Pierce County, Washington Figure 8

34 !0!0 B-2 E E' Office: SEA Path: \\tac\projects\0\ \gis\mxd\geoengineers\ _x-sections_11x17l_e-e'.mxd Map Revised: 13 January 2014 maugust Feet 4,270 4,265 4,260 4,255 4,250 4,245 4,240 4,235 4,230 0 Data Source: APE (west) 60 Projection: NAD 1983 StatePlane Washington South FIPS 4602 Feet Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication Culvert SR410 Roadway Centerline 160 Roadway E - E' OHWM Stream 220 Feet OHWM APE (east) µ Feet Culvert/Bridge 3 Cross Section E - E' Crystal Mountain Boulevard Upgrade Pierce County, Washington Figure 9

35 Culvert 3 F!0!0 B-1 F' Office: SEA Path: \\tac\projects\0\ \gis\mxd\geoengineers\ _x-sections_11x17l_f-f'.mxd Map Revised: 13 January 2014 maugust Feet 4,270 4,265 4,260 4,255 4,250 4,245 4,240 0 Data Source: Est. Wetland 60 Projection: NAD 1983 StatePlane Washington South FIPS 4602 Feet Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. 80 APE (west) OHWM Stream 100 OHWM Wetland 120 SR Roadway 160 Centerline 180 Roadway 200 F - F' 220 Feet 240 APE (east) µ Feet Culvert/Bridge 3 Cross Section F - F' Crystal Mountain Boulevard Upgrade Pierce County, Washington Figure 10

36 3,780 G C L BRIDGE G' 3,950 H C L BRIDGE H' ELEVATION 3,770 3,760 3,750 3,740 3,730 B-6 GP-GM GM GP-GM GM GP-GM BOULDER GM APPROXIMATE BASE OF CREEK POSSIBLE SCOUR DEPTH B-5 GP-GM GP GM BOULDER SM/ML SOFT OL/ML/PT GM/GP-GM ELEVATION 3,940 3,930 3,920 3,910 3,900 B-4 GP-GM GM SM/ML GM BOULDER APPROXIMATE BASE OF CREEK POSSIBLE SCOUR DEPTH B-3 GP-GM GM GP GM ML SM GP-GM/ GM/GP BEDROCK 3,720 3,890 BEDROCK BEDROCK 3,710 3,880 3,700 ROCK? BOULDER? BRIDGE 1 BRIDGE 2 I C L BRIDGE I' 4,250 B-2 B-1 GM 4,240 GP-GM GP-GM GM ELEVATION 4,230 4,220 GM BEDROCK APPROXIMATE BASE OF CREEK POSSIBLE SCOUR DEPTH GP-GM GM BEDROCK 4,210 BEDROCK HORIZONTAL SCALE: 1"= 20' VERTICAL SCALE: 1"= 20' VERTICAL EXAGGERATION: 1X ,200 BRIDGE 3 FEET Notes 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Reference: GeoEngineers staff sketch. B-1 SM Legend Boring Inferred Soil Contact Soil Classification Blow Count Longitudinal Cross Sections Crystal Mountain Boulevard Upgrade Pierce County, Washington Figure 11

37 30 Shallow Foundation Bearing Capacity Crystal Mountain Boulevard Bridge Foundations on Soil NLT SharePoint\ \Working\ShallowFoundationCapacity-Elastic Settlement_Validated 2011.xlsx Bearing Capacity (ksf) Footing Width (ft) Extreme Event Strength Limit State Service Limit State; 1-inch settlement Shallow Foundation Design - Soil Figure 12

38 360 Shallow Foundation Bearing Capacity Crystal Mountain Boulevard Bridge Foundations on Bedrock 340 NLT SharePoint\ \Working\ShallowFoundationCapacity-Elastic Settlement_Validated 2011.xlsx Bearing Capacity (ksf) Footing Width (ft) Extreme Event Strength Limit State Service Limit State; 1-inch settlement Shallow Foundation Design - Bedrock Figure 13