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HomeMy WebLinkAboutGeoTech Engineering Design Study Additions/Renovations - COM Engineering / Geo-Tech Reports - 8/19/2002 Geotechnical Engineering Design Study Additions/Renovations Geotechnical Engineering Design Study Alderbrook Resort Additions/Renovations Union, Washington mw ROWS Prepared for North Forty Lodging, L.L.C. August 19, 2002 7748 t/ www.hartcrowser.com Delivering smarter solutions Anchorage Geotechnical Engineering Design Study Alderbrook Resort Additions/Renovations Union, Washington Boston Denver Prepared for North Forty Lodging, L.L.C. Edmonds August 19, 2002 7748 Eureka Prepared by Hart Crowser, Inc. FREY Jersey City 2, N. John Bingham o Z Juneau Project Geotechnical Engineer w 1 STb4F�G�� AL � II ll EXPIRES 3 ( Z bong Beach W atina n dams i �"`'' J. Jeffrey Wagner, P.E. Senior Associate Principal Geotechnical Engineer Portland Seattle 1910 Fairview Avenue East Seattle, Washington 98102-3699 Fax 206.328.5581 Tel 206.324.9530 CONTENTS Page INTRODUCTION 1 PURPOSE, SCOPE, AND LIMITATIONS OF THIS STUDY 1 Purpose 1 Scope Limitations SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS PROJECT UNDERSTANDING 4 The Site 4 The Development SUBSURFACE CONDITIONS 7 General Subsurface Soil Conditions 6 Perched and Non-Perched Groundwater 8 GEOTECHNICAL ENGINEERING DESIGN RECOMMENDATIONS 8 General 8 Site Preparation g Foundation Support Alternatives 10 Shallow Foundations 1 Lateral Pressures on Subgrade Walls 16 Temporary Open Cuts 17 Structural Fill Selection, Placement, and Compaction 18 Drainage Considerations 20 Pavement Sections 21 Subsurface Utilities 21 Seismic Considerations 23 RECOMMENDED ADDITIONAL GEOTECHNICAL SERVICES 23 REFERENCES 24 Hart Crowser Page i 7748 August 19,2002 CONTENTS (Continued) Page FIGURES 1 Vicinity Map 2 Site and Exploration Plan APPENDIX A FIELD EXPLORATIONS METHODS AND ANALYSIS A-1 Explorations and Their Location A-1 The Use of Auger Borings A-1 Standard Penetration Test (SPT) Procedures A-1 FIGURES A-1 Key to Exploration Logs A-2 and A-6 Boring Logs HC-B6 and HC-B10 APPENDIX B LABORATORY TESTING PROGRAM B-1 Soil Classification B-1 Water Content Determinations B-1 Grain Size Analysis (GS) B-1 Atterberg Limits (AL) B-2 FIGURES B-1 Unified Soil Classification (USC) System B-2 and B-3 Particle Size Distribution Test Report B-4 Liquid and Plastic Limits Test Report Hart Crowser Page ii 7748 August 19,2002 GEOTECHNICAL ENGINEERING DESIGN STUDY ALDERBROOK RESORT ADDITIONS/RENOVATIONS UNION, WASHINGTON INTRODUCTION This report presents the results of our subsurface explorations and our geotechnical engineering design recommendations for the proposed Alderbrook Resort additions/renovations in Union, Washington. Figure 1 is a Vicinity Map of the project area, and Figure 2 is a Site and Exploration Plan showing the locations of soil borings that were advanced by Hart Crowser for this study. This report contains several sections. The first few pages introduce the main topics and summarize our principle geotechnical engineering design recommendations. The main body of the report presents our design level recommendations in more detail. The report is organized as follows: ■ Introduction; ■ Purpose, Scope, and Limitations of this Study; ■ Summary of Conclusions and Recommendations; ■ Project Understanding; ■ Subsurface Conditions; ■ Geotechnical Engineering Design Recommendations; and ■ Recommended Additional Geotechnical Services. Our figures and appendices follow the main body of the text. Appendix A presents geotechnical exploration logs from our fieldwork at the site. Appendix B includes our geotechnical laboratory testing results. PURPOSE, SCOPE, AND LIMITATIONS OF THIS STUDY Purpose The purpose of our work has been to: ■ Assess subsurface conditions; ■ Consider foundation alternatives; ■ Provide design level geotechnical engineering recommendations; and ■ Provide consultation relevant to additional design and construction. Hart Crowser Pagel 7748 August 19,2002 Scope Our scope of our work has included the following: ■ Field explorations at the project site; ■ Geotechnical laboratory tests of selected soil samples collected during our explorations; ■ Development of geotechnical engineering design recommendations; and ■ Preparation of this report. The subsurface investigation program for this study consisted of five borings. Geotechnical test results were used to classify site soils and to estimate their geotechnical engineering properties. Limitations We completed this work in general accordance with our proposal dated May 1, 2002. We received your authorization to proceed dated May 5, 2002. Our report is for the exclusive use of North Forty Lodging, L.L.C. and their design consultants for specific application to the subject project and site. We completed this study in accordance with generally accepted geotechnical practices for the nature and conditions of the work completed in the same or similar localities, at the time the work was performed. We make no other warranty, express or implied. SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS This section summarizes the principal conclusions and recommendations made within the report. The subsequent sections should be consulted for further discussion of each point, as well as for additional recommendations. Project Description Site development consists of renovation and demolition of existing structures (Figure 2) as well as new construction. The following list highlights the main construction items that would require geotechnical input, based on our current understanding of the project. ■ The existing Alderbrook Inn, to the west, may have additional foundation loads due to remodeling activities. Hart Crowser Page 2 7748 August 19,2002 ■ A new two-story lobby with conference rooms below will be constructed between the Alderbrook Inn and the new guest rooms. ■ A new ballroom will be constructed in the first level of the westernmost new guest room building. ■ The two existing motels, adjacent to SR 106, are to be demolished and relocated further south with a similar finish floor elevation. The first floor of the new motels will be daylighted to the north, and thus, include retaining walls on the south side. ■ The existing guest rooms/shop at the south end of the Eastwood Building is to be demolished and relocated slightly further west. Subsurface Conditions South of the existing motels, subsurface soils generally consist of loose, silty, poor quality fill soil overlying dense, glacially overridden soil. North of the existing motels loose to medium dense pit-run fill overlies medium dense, silty, gravelly sands that transition to dense glacially overridden deposits at depth. The fills range in thickness from about 7 to 10 feet. South of the existing motels, perched groundwater was encountered at a depth of about 8 feet. North of the existing motels, the groundwater table was encountered between depths of 7 and 12 feet. Foundation Support New Foundations. We understand that new construction will typically consist of lightly loaded structures. In general, these light loads should be suitably supported by shallow foundations bearing on new structural fill over medium dense native soils. If overexcavation of existing fill soils is not practical or structural loads are heavy, other foundation support alternatives should be considered (e.g., augercast piles, pin piles, or geo-piers). Alternatively, only in the area north of the existing motels, if the owner is willing to accept more risk, light structural loads may be supported on shallow foundations that bear on a minimum thickness new structural fill overlying medium dense non-yielding existing fill soils. Additional Loads on Existing Foundations. Our discussions with the project structural engineer indicate that the current footings for the Inn appear to be designed to use most of the allowable soil bearing pressure originally assigned Hart Crowser Page 3 7748 August 19,2002 (4,000 pounds per square foot [psf]). Therefore, it may be necessary to enlarge the existing footings, or use alternate foundation support methods if significantly higher loads are applied to these footings. Based on the performance of the existing structures, it is likely that the allowable bearing pressure could be increased somewhat. However, we recommend that Hart Crowser observe exposed footing subgrade soils to verify their suitability to support the additional applied loads. This could provide a significant construction cost savings over alternative foundation retrofit options. Floor Slabs In our opinion, floor slabs may be constructed as a slab-on-grade on a minimum 2-foot thickness of new structural fill overlying medium dense existing fill or native soil. With this approach that allows existing fill soil to remain in-place, there is added risk to the owner of non-uniform settlement of the slab-on-grade (compared to complete removal of existing fill) because of the potential variable nature of the existing fill soils. However, in our opinion, this is a reasonable approach. Lateral Loads on Subgrade Walls For basement or retaining walls backfilled on one side only and with suitable drainage, compute lateral loads using a triangular pressure distribution. Use an equivalent fluid density of 35 pounds per cubic foot (pcf) (active conditions) and 55 pcf(at rest conditions) above the water table. PROJECT UNDERSTANDING The Site The site is located between State Route 106 (SR 106) and Hood Canal as shown on Figure 1. The site currently consists of the following buildings/areas: ■ Alderbrook Inn to the west (four stories including a daylight basement); ■ Two motel buildings to the south (three stories including daylighted ground floor to north); ■ Eastwood Building to the east (one-story conference room to north with attached two-story guest rooms and shop to the south); ■ The pool to the northeast; and Hart Crowser Page 4 7748 August 19,2002 ■ A courtyard area with covered walkways between these buildings. Current site grades vary from about 30 feet elevation to the south to about 16 feet elevation Mean Lower Low Water (MLLW) to the north within the proposed extent of new construction as shown on Figure 2. There is a significant elevation difference between the north and south sides of the existing motels since the lowest level is daylighted to the north with a retaining wall on the south side. The Development We understand that the proposed development generally will consist of renovating existing buildings, expanding existing building footprint(s), and demolishing and relocating buildings as shown on Figure 2. Specific building loads were not known at the time this report was prepared. We understand the following specific information about the development: ■ The Alderbrook Inn will be renovated with no change in footprint or the number of stories; ■ Plans for the existing Inn indicate that an allowable soil bearing pressure of 4,000 psf was used in the original design; ■ A new two-story lobby with conference rooms below will be constructed connecting the Inn to the westernmost guest room building; ■ The first level of the westernmost guest room building will incorporate a new ballroom; ■ The two existing motel buildings will be demolished and relocated closer to SR 106 at a finish floor elevation similar to the current finish floor elevation (i.e., about 19 feet); ■ Construction of the new guest rooms will incorporate open cuts to facilitate retaining wall construction; ■ The new guest rooms will include the same number of floors as the existing motels; ■ The existing guest room/shop area will be demolished, relocated slightly to the west, and include the same number of stories; ■ The existing Eastwood conference room and Pool will be renovated with no change in footprint or number of stories; and ■ Final site grades will remain similar to existing grades. SUBSURFACE CONDITIONS Subsurface information presented within this report is based upon data collected during our explorations on May 7 through 9, 2002. Explorations consisted of five geotechnical borings advanced to depths of about 28 to 42 feet. The Hart Crowser Page 5 7748 August 19,2002 locations of the explorations are shown on Figure 2, Site and Exploration Plan. Subsurface soil conditions interpreted from explorations at discrete locations formed the basis for developing our conclusions and recommendations contained within this report. The nature and extent of variations between explorations may not become evident until construction. If variations then become apparent, it will be necessary to re-evaluate the recommendations in this report. General Subsurface Soil Conditions Generally soil conditions south of the existing motels are somewhat different than those north of the existing motels. Primarily this is in regards to the apparent quality of the existing fill material near the ground surface. South of the existing motels (HC-B7 and HC-138), subsurface soils generally consist of poor quality, loose to medium stiff fill soil over dense to very dense glacially overridden granular soils. North of the motels (HC-136, HC-139, and HC-B10), loose to medium dense granular fill overlies medium dense, slightly silty, gravelly sands that transition to dense glacially overridden granular soils at depth. Observations from the borings and available geologic maps (see REFERENCES section) indicate that the site is located in a transition area between glacially consolidated soils sloping down the hillside toward the north and alluvial deposits of Hood Canal. Major soil units are described below in descending order from the ground surface. They include: ■ Sand/Silt Fill—South of Existing Motels. South of the existing motels about 2 inches of asphalt overlie about 18 inches of moist, slightly silty to silty, gravelly Sand (possible pavement subgrade fill). In HC-138, the very loose to loose, silty, gravelly Sand appears to extend down to about 8 feet below the surface. However, in HC-137 medium stiff, moist, gravelly, very sandy Silt with wood debris and charcoal fragments extends below the overlying sand down to about 7 feet below the surface. We consider this fill material unsuitable for support of shallow footings. ■ Pit-Run Fill—North of Existing Motels. North of the existing motels, medium dense, moist, slightly silty, very sandy Gravel with cobbles (fill) was encountered from the ground surface to depths of about 7 to 10 feet. Although this fill material generally appeared to be of good quality, a zone of very loose to loose soil was encountered in HC-139 between depths of 9 and 14 feet. It is difficult to determine whether this loose zone is part of the fill or the underlying sand since no soil sample was recovered in this zone. Hart Crowser Page 6 7748 August 19,2002 We do not have first hand knowledge of the existing fill placement or records of its placement, composition, or consistency and thus, consider it to be "uncontrolled fill." Because it may have been placed in an uncontrolled manner, the existing fill density and consistency may be quite variable. It may contain significant zones of loose or soft soils, wet silty soils, or organic material (e.g., topsoil, roots, stumps, etc.) that were not encountered in our borings. Such materials are not suitable for shallow footing foundation support. Based on our current subsurface information, we feel that this fill, because of its potential variability, is generally not suitable for shallow footings support without some risk of non-uniform settlement. However, due to the relatively low percentage of silt and clay in this material, it may be suitable for reuse as structural fill as outlined later in this report. ■ Medium Dense Sand (Native Soil). This unit consists of medium dense, moist to wet, very silty sand to slightly silty, very gravelly Sand. It was only encountered in the courtyard area north of the existing motels and is about 13 feet thick to the south (HC-B6) and up to 24 feet thick to the north (HC-B10). This unit appears to represent alluvial deposits overlying the glacially overridden soils sloping downward toward the north. We generally consider this material to be a suitable bearing layer for shallow footings. In HC-139, we encountered an apparent 5-foot-thick zone of very loose to loose, slightly silty sand (previously discussed as potential fill material), which we interpret to be a small isolated zone since it was not encountered in the other four borings. This localized zone may liquefy during the design level earthquake because of its density and presence below the groundwater table. However, we anticipate that any potential liquefaction-induced settlement would also occur in a small localized area, as discussed later in this report. In HC-1310, a 7-foot-thick layer of stiff, silty, sandy to very sandy Clay was encountered at a depth of 31 feet below the surface. We expect that this clay only exists in a localized area since it was not encountered in the other four borings. Due to its depth and stiffness, we do not expect that significant consolidation of this layer will result from the expected relatively light foundation loads in this area. ■ Dense Glacially Overridden Sand (Native Soil). Dense to very dense, gravelly, silty to very silty Sand to silty, very sandy Gravel was encountered at depths ranging from 8 feet in HC-137 to 38 feet in HC-B10, and extended to the bottom of our explorations. The depths to glacially overridden soils Hart Crowser Page 7 7748 August 19.2002 across the site indicate that this unit slopes downward to the north, toward Hood Canal. This material would also serve as a suitable bearing layer for shallow or deep foundations. Perched and Non-Perched Groundwater We observed perched groundwater at an elevation of about 20 feet (8 feet below existing grade) in HC-138 with underlying moist zones. No water was observed in HC-137. This appears to indicate perched water conditions south of the existing motels. North of the motels, the groundwater table was encountered between about elevations 10 and 6 feet (between 7 to 12 feet below existing grades) at the time of drilling and after allowing the water level to stabilize. In our opinion, this represents the true groundwater level. It should be noted that water levels were measured at the times and under the conditions stated on the boring logs. Fluctuations in the groundwater conditions may occur due to variations in tides, rainfall, temperature, seasons, and other factors. GEOTECHNICAL ENGINEERING DESIGN RECOMMENDATIONS This section of the report presents our conclusions and recommendations regarding the geotechnical aspects of design and construction for the project. We have developed our recommendations based on our current understanding of the project and the results of our subsurface explorations. If the nature or location of the facilities is different than we have assumed, Hart Crowser should be notified so we can change or confirm our recommendations. General We anticipate that the major design elements for this site will be: ■ Shallow foundation support for new additions; ■ Shallow foundation support for existing footings where additional loads will be applied due to remodeling; and ■ Retaining wall support for new guest rooms that are near the existing SR 106. Currently, we understand and have assumed that all new foundation loads will be relatively light. Since variable fill soils were encountered to depths ranging from about 7 to 10 feet below the ground surface, proper design, site preparation, and construction will be necessary to support these light loads on Hart Crowser Page 8 7748 August ts.2002 shallow foundations. In general, we recommend that shallow footings bear directly on medium dense to dense native soil or on new structural fill placed directly on this native soil. We expect that this would require significant overexcavation of existing fill soils. There may be an alternative to this overexcavation, in the area north of existing motels. That would be to found shallow footings within the existing relatively good quality, granular fill. However, this would require additional explorations, a reduced allowable bearing pressure, and the acceptance of additional risk by the owner as subsequently discussed. If shallow footings are not used because the owner does not want to accept more risk, overexcavation through the fill is not practical, or foundations loads are heavy, Hart Crowser should be retained so that we may provide design recommendations for deep foundations or other alternatives. Such recommendations are not included in this report. The following sections in this report provide design and construction recommendations for the anticipated lightly loaded foundations. Site Preparation Shallow Foundation and Slab-on-Grade Preparation Site preparation for any lightly loaded shallow foundations and slabs-on-grade should include the removal of any existing pavement and structures (including footings). Existing abandoned utilities or utilities to be abandoned should be backfilled with lean concrete or removed. Exposed ends should be plugged. Any visible organic and/or deleterious material should be removed. The exposed excavated surface should be proof rolled with heavy, vibratory compaction equipment or a fully loaded dump truck to delineate any soft or loose areas of soil. Soft, loose, wet, or yielding material should be removed and replaced with, or recompacted as, structural fill as described in the Structural Fill Selection, Placement, and Compaction section of this report. Existing soils below footings should be overexcavated as required so that footings or new structural fill bear directly on medium dense to dense native soil. Existing soil beneath slabs-on-grade should be overexcavated as required so that the slabs bear on a minimum thickness of dense granular material as discussed subsequently. Hart Crowser Page 9 7748 August 19,2002 We recommend that a representative from Hart Crowser be present to observe subgrade preparation activities and to assist the contractor in identifying areas requiring recompaction or overexcavation. Drainage/Seepage Control Groundwater was encountered at depths ranging from 7 to 12 feet below existing grades. We do not anticipate that construction will be performed to these depths with the exception of possible overexcavation and deeply buried utilities. We anticipate that in most cases continuous ditching and sumping with pumping will be sufficient to control surface water runoff and/or minor seepage, and allow construction by conventional methods. The on-site geotechnical engineer during construction should re-assess these conditions and procedures during construction. Temporary Open Cuts Temporary open cuts should be performed in accordance with recommendations in the Temporary Open Cuts section of this report. Foundation Support Alternatives Shallow foundations are typically the most cost-effective method to support relatively light structural loads. The following sections present shallow foundation options followed by other foundation support alternatives. Existing Foundations As previously indicated, the footings for the existing Inn appear to be designed to use most of the allowable soil bearing pressure originally assigned. Therefore, if significantly higher loads are applied to these existing footings and additional explorations/observations do not reveal adequate subgrade soil conditions, it will be necessary to enlarge these existing footings or use alternate foundation support methods. It may be possible to slightly increase the allowable bearing pressure for the existing Inn footings depending on the subgrade conditions at each footing and the amount of additional load. See Shallow Foundation section for further recommendations. New Foundations Based on our understanding that new construction will typically consist of lightly loaded structures, we feel that shallow foundations bearing on structural fill over medium dense native soils should provide suitable support. North of the Hart Crowser Page 10 7748 August 19,2002 existing motels, another less expensive option, involving more risk, would be to found new footings on structural fill over medium dense fill. See Shallow Foundations section for further recommendations. Both these options assume that adequate site preparation is performed as outlined in this report. If shallow footings are not practical due to soil conditions or heavy structural loads, alternative foundation support methods discussed below may be needed. Other Alternatives The following list summarizes what we feel are the most feasible foundation alternatives starting with those generally considered to have the lowest construction cost. However, specific cost estimates should be completed before selecting an alternative. Geo-Piers. Geo-piers are columns of compacted stone aggregate used to improve the support capability of loose soils. Typical depths are 5 to 12 feet below grade. They are constructed by drilling a 1.5- to 3-foot-diameter hole in the ground, and placing and compacting stone aggregate in about 12-inch-thick lifts. Typically, geo-piers are installed at 1.5- to 2-diameter center-to-center spacings. This option is essentially the same as overexcavation and replacement with structural fill except that the lateral extent is limited to the hole diameter. Although not included herein, we can provide additional design recommendations for geo-piers if requested by the owner. Pin Piles. If existing Inn footings cannot be used or modified to support additional loads, pin piles may be used with the footings to support additional loads. The pin piles can be driven immediately adjacent to footings or through holes cored in the footings, and are ideal for limited access locations. Pin piles typically consist of small diameter steel pipes driven into the subgrade to a point of refusal. Individual pipe segments typically range from about 3 to 5 feet long and are successively joined with external threaded couplings, internal slip couplings, or are butt welded, as pile driving progresses. Typical capacities for 2-, 3-, and 4-inch-diameter pin piles are 4 to 6, 10 to 12, and 16 to 18 kips, respectively. We anticipate the piles will meet refusal in deeper dense sand or gravel soils, or in a shallower zone of gravel or cobbles. We expect the piles may penetrate up to 35 feet to meet refusal. Because soil conditions could vary, the contractor should be prepared for variable pile lengths. We can provide additional design and installation recommendations for pin piles if requested by the owner. Augercast Piles. If foundation loads exceed those appropriate for shallow footings, augercast piles may be used for foundation support. Typical diameters for augercast piles are 14, 16, and 18 inches with allowable capacities of 50, 60, Hart Crowser Page 11 7748 August 19,2002 and 80 tons, respectively, for about 10 feet of embedment into a suitable bearing layer. Disposal of pile cuttings may incur additional cost if the soils are contaminated. However, our explorations did not encounter noticeable soil contamination. We can provide additional design recommendations for augercast piles if requested by the owner. Shallow Foundations General We recommend shallow foundations be used for lightly loaded and settlement- tolerant facilities on site. Shallow foundations consist of continuous wall footings, isolated spread footings, and/or slabs-on-grade. We recommend that shallow foundations bear directly on medium dense to dense native soil or densely compacted structural fill overlying a non-yielding subgrade (i.e., medium dense to dense native soils). This is discussed in the Site Preparation and Structural Fill Selection, Placement, and Compaction sections. Alternatively, if the owner is willing to accept more risk, light structural loads may be supported on shallow foundations that bear on structural fill overlying medium dense non-yielding existing fill soils. This option is only applicable north of the existing motels. However, due to the potentially variable nature of the existing fill soils discussed previously, there is some increased risk of differential settlement of shallow foundations if constructed over this fill. Site preparation, as outlined in this report, should reduce the potential for such non-uniform settlements. The following sections describe our design recommendations for shallow footings and slabs-on-grade. Shallow Footings Plans for the existing Inn indicate an allowable soil bearing pressure of 4,000 psf was used in the original design. This bearing pressure has apparently been appropriate for the existing footings based on satisfactory performance of buildings and visible foundation elements. However, our explorations indicate fill of variable density and consistency as indicated above. Therefore, we feel that different bearing pressures are appropriate for different areas as discussed in the following sections. Hart Crowser Page 12 7748 August 19,2002 New Footings For new shallow footings, we recommend the following: ■ Design footings to bear on medium dense to dense native granular soil or on structural fill that is placed directly above medium dense to dense native granular soil. ■ Use a maximum allowable soil bearing pressure of 3,000 psf. ■ Foundation settlement and final bearing pressures will be a function of the total applied loads and should be evaluated once design loads and approximate footing sizes become available. The allowable bearing pressure presented above is for dead loads and frequently applied live loads. It may be increased by one-third for loads of short duration, such as-wind or seismic loads. ■ Footings should be founded outside of an imaginary 1 H:1 V plane projected upward from the bottom edge of adjacent footings or utility trenches. ■ The lateral extent of any overexcavation should extend outward and downward at an angle of 1 H:1 V from the edge of the footing to the top of the bearing layer. ■ Design footings so that: • Isolated footings have a minimum dimension of 24 inches; • Continuous wall footings have a minimum width of 18 inches; and • All footings have a minimum embedment depth of 18 inches below the lowest adjacent grade for consideration of frost depth. ■ Use an ultimate coefficient of friction of 0.45 for cast-in-place concrete bearing on medium dense to dense granular soil to estimate sliding resistance on the base of shallow foundations. ■ Ultimate passive resistance of footings surrounded by structural fill can be modeled using an equivalent fluid densities of 350 and 150 pcf to represent pressure applied by the soil above and below the water table, respectively. ■ We recommend applying a factor of safety of 1.5 when computing resistance to lateral loads. Hart Crowser Page 13 7748 August 19,2002 ■ We expect that post-construction settlements for lightly loaded new footings designed and constructed as recommended will be approximately 1 inch or less. We anticipate that differential settlements between adjacent footings will be approximately one-half of the total settlement. We recommend that Hart Crowser be afforded the opportunity to confirm settlement estimates once final design loads and layout are known. These recommendations are based on expected conditions and need to be confirmed in the field. Alternative Footing Design North of Existing Motels As previously discussed, if the owner is willing to accept added risk of post- construction settlement, an alternative footing design may be used north of the existing motel. This involves only partial overexcavation of the existing fill soils and can be considered only because the fill in this area appears to be medium dense to dense, granular, and free of organics. For this approach, we recommend the following: ■ Advance a number of borings or test pits within the building footprint to further assess the nature of the existing fill. ■ Remove existing fill to a depth of 3 feet beneath proposed footings. Remove any additional unsuitable, organic, or deleterious material that is exposed. ■ Compact the exposed subgrade to a dense condition. ■ Place new structural fill to the proposed footing subgrade elevation. It may be possible to use the excavated material as structural fill. ■ Use maximum allowable bearing pressure of 2,000 psf for design. ■ Additional footing design recommendations previously presented herein are also applicable for this approach. Existing Footings with Additional Loads For existing footings with additional loads, we recommend the following: ■ Based on performance of the Inn, we feel that the original 4,000 psf allowable bearing pressure is appropriate for subgrade conditions Hart Crowser Page 14 7748 August 19,2002 underneath existing footings. In our opinion, it would be acceptable to increase this maximum allowable soil bearing pressure to 4,500 psf under the existing Inn footings only. Settlement at these locations generally would have occurred by now and we feel that the additional pressure of 500 psf would not lead to significant additional settlement. We estimate that the original design allowable value of 4,000 psf included a factor of safety of 3 against a bearing capacity failure. It may be possible to increase the bearing pressure more at specific footings on a case-by-case basis depending on the additional load and the subgrade conditions. However, we would need to observe and confirm adequate subgrade conditions. Otherwise, existing footings will need to be enlarged, or alternative foundation support methods previously mentioned will need to be used. Foundation Construction The foundation settlements estimated above assume that careful preparation and protection of the exposed subgrade and required underlying dense zone will occur prior to concrete placement. Any loosening of the materials during construction or the presence of loose, soft, or organic material beneath footings could result in larger settlements than those estimated herein. It is important that all foundation excavations be cleaned of loose or disturbed soil prior to placing any concrete and that there be no standing water in any foundation excavation. These conditions should be documented during construction. Depending on the time of construction and conditions at the bottom of the excavation, it may be necessary to place a nominal 2- to 4-inch-thick "mud slab" (consisting of lean concrete) in footing excavations immediately after the excavation has been checked by the geotechnical engineer. The purpose of the mud slab would be to protect the exposed soils against softening or disturbance from water or construction activities. Floor Slabs Conservatively, floor slabs may be constructed as slabs-on-grade that bear on structural fill after complete removal of existing fill soils. However, in our opinion, it is reasonable to design floor slabs so that they bear on a minimum 2-foot thickness of structural fill, overlying the existing fill. With this approach, the owner is accepting added risk of post-construction differential settlement of the floor slab. This is due to the potential variable nature of the fill soils that would be left in place. In our opinion, this is a reasonable approach Hart Crowser Page 15 7748 August 19,2002 that has been used successfully in the past provided that the subgrades are prepared as recommended herein. For slabs-on-grade we recommend the following: ■ Design slabs-on-grade to bear on at least 2 feet of structural fill overlying a firm non-yielding subgrade. ■ Overexcavate the existing fill, proofroll the exposed subgrade beneath the new fill, and compact the exposed subgrade to a dense, non-yielding condition. ■ Remove any soft, loose, or otherwise unsuitable soils and replace them with structural fill. ■ Do not structurally connect slabs-on-grade to the column support elements (footings or pile caps). This will allow for potential differential settlement between the slabs and foundation supports, allowing the slab to "float." ■ Install a capillary break layer directly beneath the slab as described in the Drainage Considerations section. ■ Provide a vapor barrier beneath the slab-on-grade. ■ Use a modulus of subgrade reaction of 150 pounds per cubic inch (pci), based on a 1-foot square plate for slabs supported on structural fill as described elsewhere in this report. Lateral Pressures on Subgrade Walls The structural engineer can estimate the lateral load and resistance on the walls using an equivalent fluid to represent the soil for basement or retaining walls backfilled on one side only. We make the following recommendations for walls with backfill material placed per structural fill recommendations: ■ Backfilled walls should be designed to resist an active equivalent fluid density of 35 and 55 pcf for yielding and non-yielding walls above the water table, respectively. If the walls need to resist water pressures, an active equivalent fluid density for the soil of 20 and 30 pcf should be used in addition to 62.4 pcf of hydrostatic pressure for yielding and non-yielding walls, respectively. ■ Resistance to sliding for backfilled walls may be provided by friction under the wall and passive pressure in front of the embedded part of the wall. We Hart Crowser Page 16 7748 August 19,2002 recommend using the same design values for friction and passive earth pressure as for the shallow footings. ■ To account for short-term increases in lateral load on subgrade walls, apply an additional equivalent fluid pressure of 6H psf, (where H is the height of the wall in feet) for yielding walls and 16H for non-yielding walls. Yielding walls are those that can deflect laterally at the top-of-wall location by an amount equal to 0.001 times the height of the wall. Note that the lateral pressures indicated above do not include any surface/ surcharge loading conditions. Footings that are behind and adjacent to subgrade walls will impose additional lateral loads on the walls. These lateral loads should be incorporated into the wall design. Uniform surcharges may be estimated using an applied later pressure equal to 35 percent of the surcharge load for active conditions and 50 percent for at rest conditions. Temporary Open Cuts This section presents general design recommendations for temporary open cut slopes. The stable slope for cut and fill slopes depends on the following factors: ■ The presence, quantity, and location of water; ■ The type, density, and strength of the excavated soil; ■ The depth of the cut; and ■ Surcharge loading (i.e., existing or future structures, construction equipment, or stockpiled soils, etc.) adjacent to the cut. We make the following general recommendations for cut slopes. ■ Open excavations made in proximity to existing structures and utilities should be made with great care and attention. The contractor should be responsible to verify all existing utility locations and coordinate their relocation as necessary. ■ Construction equipment and activity should be maintained at least 5 feet back from the top of slopes. ■ For planning purposes, we recommend temporary open cut slopes in fill soils be no steeper than 1-1/2 horizontal to 1 vertical (1-1/2H:1V) for excavation. The 1-1/2H:1V slope assumes that the groundwater table will be lower than Hart Crowser Page 17 7748 August 19,2002 the bottom of excavation. The temporary cut slope may be steepened to 1 H:1 V in medium dense to dense native soils above the groundwater. Localized sloughing may occur during construction, and the exposed slope face will probably need to be protected from surface erosion. ■ Groundwater conditions encountered at the time of construction may dictate that slopes flatter than these will be necessary. Stability of actual temporary cut slopes should be made the responsibility of the contractor, since they are in control of the construction operation and are continuously present at the job site to observe the nature and conditions of the subsurface material encountered. The contractor should also be required to perform all excavations in accordance with federal, state, and local regulations. Structural Fill Selection, Placement, and Compaction Backfill placed within the building area, behind walls, or below paved areas should be considered structural fill. The following sections include our recommendations for structural fill material and placement. Reuse of Site Soil as Structural Fill The suitability of excavated site soil for compacted structural fill will depend upon the gradation and moisture content of the soil when it is placed. As the amount of fines (that portion passing the No. 200 sieve) increases, the soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult to achieve. Soil containing more than about 5 percent fines cannot be consistently compacted to a dense non- yielding condition when the water content is greater than about 2 percent above or below optimum. Reusable soil must also be free of organic and other deleterious material. In general, our explorations indicated that the pit-run fill north of the motels consists of slightly silty, very sandy gravel. The majority of the surficial soils north of the motels appears to contain less than 10 percent fines and may be suitable for reuse as structural fill. However, the majority of the surficial soil south of the motels appears to contain more than 10 percent fines, will be moisture-sensitive, and may be difficult to use as structural fill. Provided that organics are not included, it may be possible to use these siltier soils if moisture-conditioning is feasible during extended dry weather periods. If moisture-conditioning is not feasible, we recommend using imported soil, containing no more than 5 percent fines, as structural fill. Depending on landscaping requirements it may be appropriate to reuse the soil with more than 5 percent fines as landscape fill in Hart Crowser Page 18 7748 August 19,2002 non-structural areas. Site soils would generally be suitable for use as landscape fill, provided that their moisture content allows them to be compacted to a reasonable degree. Selection of Import Fill We recommend using a clean, well-graded sand or sand and gravel with less than 5 percent passing the U.S. Number 200 sieve by mass (based on the minus 3/4-inch fraction) for import structural fill placed during wet weather periods. Compaction of material containing more than about 5 percent fine material may be difficult if the material is wet or becomes wet during rainy weather. During dry weather, import soil can contain 20 to 30 percent by weight passing the No. 200 mesh sieve (based on the minus 3/4-inch fraction) provided it is compacted at a moisture content within 2 percent of the optimum moisture content. Placement and Compaction of Structural Fill We make the following recommendations for the proposed additions: ■ Before fill control can begin, the compaction characteristics must be determined from representative samples of the structural and drainage fill. Samples should be obtained as soon as possible, but at least 3 days prior to use on site. A study of compaction characteristics should include determination of optimum dry density, and optimum and natural moisture contents of these soils at the time of placement. ■ Structural fill may consist of either imported soil (as previously described) or on-site soils that are free of organics, if suitable moisture content is attained and weather conditions allow. ■ Beneath structural elements, compact structural fill to a minimum of 95 percent of the modified Proctor (ASTM D 1557) maximum dry density. ■ Maintain moisture content within 2 percent of the optimum moisture content (ASTM D 1557). ■ Within 3 feet of subgrade walls, compact structural fill to 90 percent to avoid overstressing the wall. ■ Structural fill should only be placed on firm, non-yielding subgrade soils. ■ Place and compact all structural fill in even lifts with a loose thickness no greater than 10 inches. If small, hand-operated compaction equipment is Hart Crowser Page 19 7748 August 19,2002 used to compact structural fill, fill lifts should not exceed 6 to 8 inches in loose thickness. ■ In wet subgrade areas, use clean material with a gravel content (material coarser than a U.S. No. 4 sieve) of at least 30 to 35 percent. ■ The compacted densities of all lifts should be verified by testing. Any material to be used as structural fill should be sampled and tested prior to use on site, to determine its maximum dry density and gradation. Drainage Considerations As discussed in the section on groundwater, groundwater was encountered in the explorations at depths ranging from 7 to 12 feet. We do not anticipate that construction will be performed to these depths with the exception of possible deeply buried utilities and/or overexcavation. We anticipate that in most cases continuous ditching and pumping will be sufficient to control surface water runoff to allow construction. The on-site geotechnical engineer during construction can assess these procedures. We make the following drainage recommendations. Subslab and Perimeter Drains All slabs should be underlain directly by a capillary break/drainage layer at least 6 inches thick that is hydraulically connected to the perimeter footing or wall drains. This layer should consist of free-draining, well-graded sand, or sand and gravel. "Free-draining" material contains less than 3 percent by dry weight passing the No. 200 sieve (based on the minus 3/4-inch fraction of the material). This layer is intended to reduce the potential build-up of hydrostatic pressures beneath the slab and to provide a hydraulic connection to the perimeter footing or wall drains. The drains with cleanouts, should consist of at least 4-inch-diameter perforated pipe placed on a bed of, and surrounded by, 6 inches of free-draining sand and gravel. The drains should be sloped to carry the water to a sump or other suitable discharge. The size of the perforations should be compatible with the free-draining soil. Backfilled Walls All backfilled subgrade walls should include a minimum 18-inch-wide zone of free-draining, well-graded sand and gravel. The backfill/drainage medium should be continuous and envelop the perimeter drains behind the walls so that they Hart Crowser Page 20 7748 August 19,2002 are in direct hydraulic connection to each other. We recommend that drains (with cleanouts) consist of at least flinch-diameter perforated pipe that is bedded in well-graded, free-draining material. Site Drainage Final grades should be sloped to carry surface water runoff away from adjacent structures to prevent water from infiltrating near the foundation walls. Roof drainage and new pavement drainage should not be tied into the subdrain system. Pavement Sections We recommend that all pavement sections (including areas between the proposed SR 106 realignment and the existing/proposed resort development) be constructed over a subgrade surface consisting of a minimum 2 feet of dense soil, which may consist of non-yielding native soils, compacted structural fill, or a combination of these. It has been our experience that proof rolling combined with overexcavation and compaction of loose/soft near-surface soils prior to structural fill placement works well, provided the native soil consists of soil at an appropriate moisture content. This would reduce the potential for long-term settlement and pavement distress associated with the settlement. We recommend Hart Crowser observe proof rolling of all pavement subgrades to confirm that a firm and non-yielding surface exists for pavement support. Given the on-site subgrade conditions, we recommend the following pavement sections: ■ Car Parking Areas. 2-1/2 inches of Class B asphalt concrete over 4 inches of crushed rock base course. ■ Driveway and Truck Traffic Areas. 4 inches of Class B asphalt concrete over 6 inches of crushed rock base course. Subsurface Utilities Pipe Support Conventional pipe support at the base of trench excavations generally appears to be feasible. Contingent on suitable bedding (i.e., in general accordance with Sections 9-03.12(3) of the 2002 Standard Specifications for Road, Bridge, and Municipal Construction provided by WSDOT), support of the pipelines by the site soils should be possible. Hart Crowser Page 21 7748 August 19,2002 ■ Do not drop backfill material directly onto the pipe. ■ Place and compact backfill uniformly on both sides of the pipe. ■ Do not place backfill containing cobbles or boulders (particles larger than 3 inches in diameter) adjacent to the pipe walls. Seismic Considerations Our explorations indicate that only a small isolated zone (between depths of 9 to 14 feet) in one (HC-B9) of five borings contained potentially liquefiable soils. In our opinion, this limited and isolated liquefiable zone would not result in a global, widespread liquefaction of the project site. We anticipate that only minor liquefaction-induced settlement of about 1 inch would occur in isolated locations. The overlying and underlying medium dense soils are generally not susceptible to liquefaction because they are either above the water table or too dense to liquefy. Thus, any potential liquefaction-induced settlement at depth likely would not be significant at the surface because of overlying non-liquefiable soils. In our opinion, the effects of ground shaking at the site would be adequately addressed by designing the structures to the guidelines set forth in the Uniform Building Code (UBC) given the following: ■ The site is located within UBC's Seismic Zone 3 based on Figure 16-2, 1997 UBC; ■ The site's substrata are best represented by UBC Sp soil profile type with a seismic zone factor of 0.3, obtained from Table 16-J and 16-I, respectively, of the 1997 UBC; and ■ The seismic coefficients are: C,, = 0.36; and C = 0.54; based on Table 16-Q and 16-R, respectively, of the 1997 UBC. RECOMMENDED ADDITIONAL GEOTECHNICAL SERVICES Before construction begins, we recommend Hart Crowser: ■ Observe existing Inn foundation subgrade conditions, if higher bearing pressures are required at specific footings. Hart Crowser Page 23 7748 August 19,2002 ■ Advance additional borings or test pits within the building footprints if the owner selects the option to support shallow footings on the medium dense fill north of the existing motels. ■ Continue to meet with the design team periodically as the design documents become more complete; ■ Calculate settlement response once final loads and layouts are known; p Y , ■ Review any design plans to verify that the geotechnical engineering recommendations have been properly interpreted and implemented into the design; and ■ Be retained to provide further recommendations for design alternatives if appropriate. During any construction activity, we recommend that a qualified geotechnical engineer observe the following: ■ Excavation and preparation of subgrade for shallow foundations and slabs- on-grade; ■ Installation of pile foundations or other foundation alternatives (if used); ■ Placement of structural fill at the site; ■ Installation of sub-slab and foundation drainage; ■ Backfilling of utility trenches or around subgrade walls; and ■ Other geotechnical considerations that may arise during the course of construction. - The purpose of these observations is to observe compliance with the design concepts, specifications, or recommendations, and to allow design changes or evaluation of appropriate construction measures in the event that subsurface conditions differ from those anticipated prior to the start of construction. REFERENCES Department of Ecology Costal Zone Atlas, 1997. Hart Crowser Page 24 7748 August 19,2002 Molenaar, Dee, and John B. Noble, 1970. Geology and Relate Ground-Water Occurrence, Southeastern Mason County, Washington, State of Washington Department of Water Resources, Water-Supply Bulletin No. 29. Soil Survey, Mason County Washington, Series 1951, No. 9, Issued 1960. f:\docsVobs\7748\Alderbrook Resort Report.doc Hart Crowser Page 25 7748 August 19,2002 Vicinity Map t F 1 � E '(�-C WJ 11... ,,�, •,.fi J�Pof'-art Q♦ - ' 406 41 t � - a sr..i � r • x .. �a�a - 7f 2A 1 < ' s VI -14 r i , -"i . LLJ +. `' 3 Note: Base map prepared from USGS 7.5 minute quadrangle 0 2000 4000 map of Union,Washington;dated 1985. 0= Approximate Scale in Feet .Seattle Arm Union RTCn SER- 7748 8102 WASHINGTON Figure 1 Site and Exploration Plan i� Bulkhead - Extent of / Proposed New Construction HC-B10 • HC-E39 Spa • HC- 6 Lobby/ Ballrooms nest _ Conf. New G --B8 s Rooms '� R°°m H C-B7 i � x LX LLI -b w wA �O Note: Base map prepared from an electronic file provided by 0 60 120 Engineering Services Associates entitled,°Alderbrook Soils Block.dwg,"dated May 15,2002. Scale in Feet Legend: HC-1316 HC Boring Number and Location A Extent of Proposed Construction N Existing Features/Buildings I&M Ri OWSE R Existing Topography Elevation in Feet 7748 5102 Figure 2 APPENDIX A FIELD EXPLORATIONS METHODS AND ANALYSIS Hart Crowser 7748 August 19, 2002 APPENDIX A FIELD EXPLORATIONS METHODS AND ANALYSIS This appendix documents the processes Hart Crowser uses in determining the nature of the site soils. The discussion includes information on the following subjects: ■ Explorations and Their Location; ■ The Use of Auger Borings; and ■ Standard Penetration Test (SPT) Procedures. Explorations and Their Location Subsurface explorations for this project included five auger borings. The exploration logs within this appendix show our interpretation of the drilling, sampling, and testing data. They indicate the depth where the soils change. Note that the change may be gradual. In the field, we classified the samples taken from the explorations according to the methods presented on Figure A-1 Key to Exploration Logs. This figure also provides a legend explaining the symbols and abbreviations used in the log and tables. Location of Explorations. Figure 2 shows the location of explorations. In the field, they were located by hand taping from existing physical features. The ground surface elevations (Mean Lower Low Water [MLLW] datum) at these locations were interpreted from elevations shown on Figure 2. The method used determines the accuracy of the location and elevation of the explorations. The Use of Auger Borings With depths ranging from 28.4 to 41.5 feet below the ground surface, five hollow-stem auger borings, designated HC-136 through HC-B10, were drilled from May 7 to 9, 2002. The borings used a 4-inch inside diameter hollow-stem auger and were advanced with a truck-mounted drill rig subcontracted by Hart Crowser. The drilling was continuously observed by an engineer from Hart Crowser. Detailed field logs were prepared of each boring. Using the Standard Penetration Test (SPT), we obtained samples at 2-1/2- to 5-foot-depth intervals. The borings logs are presented on Figures A-2 through A-6 at the end of this appendix. Hart Crowser Page A-1 7748 August 19,2002 Standard Penetration Test(SPT) Procedures This test is an approximate measure of soil density and consistency. To be useful, the results must be used with engineering judgment in conjunction with other tests. The SPT (as described in ASTM D 1586) was used to obtain disturbed samples. This test employs a standard 2-inch outside diameter split- spoon sampler. Using a 140-pound hammer, free-falling 30 inches, the sampler is driven into the soil for 18 inches. The number of blows required to drive the sampler the last 12 inches only is the Standard Penetration Resistance. This resistance, or blow count, measures the relative density of granular soils and the consistency of cohesive soils. The blow counts are plotted on the boring logs at their respective sample depths. In the Event of Hard Driving Occasionally very dense materials preclude driving the total 18-inch sample. When this happens, the penetration resistance is entered on logs as follows: Penetration less than six inches. The log indicates the total number of blows over the number of inches of penetration. Penetration greater than six inches. The blow count noted on the log is the sum of the total number of blows completed after the first six inches of penetration. This sum is expressed over the number of inches driven that exceed the first 6 inches. The number of blows needed to drive the first six inches are not reported. For example, a blow count series of 12 blows for 6 inches, 30 blows for 6 inches, and 50 (the maximum number of blows counted within a 6-inch increment for SPT) for 3 inches would be recorded as 80/9. Soil samples are recovered from the split-barrel sampler, field classified, and placed into watertight jars. They are then taken to Hart Crowser's laboratory for further testing. F:\docs\jobs\7748\A1derbrook Resort Report.doc Hart Crowser Page A-2 7748 August 19,2002 Key to Exploration Logs Sample Description Classification of soils in this report is based on visual field and laboratory observations which include density/consistency, moisture condition, grain size, and plasticity estimates and should not be construed to imply field nor laboratory testing unless presented herein. Visual-manual classification methods of ASTM D 2488 were used as an identification guide. Soil descriptions consist of the following: Density/consistency, moisture, color, minor constituents, MAJOR CONSTITUENT, additional remarks. Density/Consistency Soil density/consistency in borings is related primarily to the Standard Penetration Resistance. Soil density/consistency in test pits is estimated based on visual observation and is presented parenthetically on the test pit logs. SAND or GRAVEL Standard SILT or CLAY Standard Approximate Density Penetration Consistency Penetration Shear Strength Resistance(N) Resistance(N) in TSF in Blows/Foot in Blows/Foot Very loose 0 - 4 Very soft 0 - 2 <0.125 Loose 4 - 10 Soft 2 - 4 0.125 - 025 Medium dense 10 - 30 Medium stiff 4 - 8 0.25 0.5 Dense 30 - 50 Stiff 8 - 15 0.5 1.0 Very dense >50 Very stiff 15 - 30 1.0 2.0 Hard >30 >2.0 Moisture Minor Constituents Estimated Percentage Dry Little perceptible moisture Not identified in description 0- 5 Damp Some perceptible moisture, probably below optimum Slightly (clayey, silty, etc.) 5- 12 Moist Probably near optimum moisture content Clayey, silty, sandy, gravelly 12-30 Wet Much perceptible moisture, probably above optimum Very (clayey, silty, etc.) 30- 50 Legends Sampling Test Symbols Test Symbols Boring Samples Test Pit Samples GS Grain Size Classification ® Split Spoon CN Consolidation ® Grab (Jar) UU Unconsolidated Undrained Triaxial N Shelby Tube Z Bag CU Consolidated Undrained Triaxial ® Cuttings Shelby Tube CD Consolidated Drained Triaxial m Core Run QU Unconfined Compression DS Direct Shear No Sample Recovery K Permeability P Tube Pushed, Not Driven PP Pocket Penetrometer Approximate Compressive Strength in TSF Groundwater Observation Wells TV Torvane Approximate Shear Strength in TSF Monument CBR California Bearing Ratio C Surface Seal MD Moisture Density Relationship s Riser Pipe AL Atterberg Limits qFATD Bentonite �.— 4 Water Content in Percent Groundwater Level on Date or Liquid Limit l at Time of Drilling (ATD) Natural Plastic Limit Well Screen PID Photoionization Detector Reading Sand Pack CA Chemical Analysis Native Material DT In Situ Density Test N Groundwater Seepage (Test Pits) U 7748 8102 Figure A-1 Boring Log HC-B6 STANDARD PENETRATION LAB Depth RESISTANCE TESTS Soil Descriptions in Feet Approximate Ground Surface Elevation in Feet:22 Sample • Blows per Foot 0 1 2 5 10 20 50 100 Medium dense(dense at surface due to traffic),moist,brown,slightly silty,sandy S-1 GRAVEL with cobbles. (Pit Run Fill) S-2 GS 5 S-3 10 A Medium dense,moist to wet, brown, S-4 s gravelly,silty SAND. Medium dense,wet, brown, very silty,fine SAND to very stiff,very sandy SILT with 15 S-5A occasional gravel. S-58 Thin 5-inch-thick layer of black and white S-5A coarse SAND. Medium dense,wet, reddish brown, slightly 20 gravelly, silty SAND. S-6 ' Dense to very dense,moist with wet zones, A�TD reddish brown,silty,very gravelly SAND to very sandy GRAVEL. (glacially overridden) 25 S-7 • 30 S-8 • GS Q 0 m 0 35 o S-9 • 0 U U Uc� co40 S-10 0 Bottom of Boring at 41.5 Feet. C� Completed 05/08/02. 0 z 0 0 m 45 1 2 5 10 20 50 100 • Water Content in Percent t1 1.Refer to Figure A-1 for explanation of descriptions and symbols. L� 2.Soil descriptions and stratum lines are interpretive and actual changes �oII.7Yl may be gradual. 3.Groundwater level,if indicated,is at time of drilling(ATD)or for date specified. Level may vary with time. 7748 05102 4. 12.5 foot water level measured inside auger after drilling and water Figure A-2 stabilized. g 5.Hand auger to 4 feet to check for utilities. Boring Log HC-B7 STANDARD PENETRATION LAB Soil Descriptions Depth RESISTANCE TESTS n Feet Sample ♦ Blows per Foot Approximate Ground Surface Elevation in Feet:30 0 1 2 5 10 20 50 100 2 inches of Asphalt over(loose to medium S-0 dense), moist,brown, slightly silty,gravelly SAND. Pit-Run Fill? Medium stiff,moist,dark brown,gravelly, very sandy SILT with wood debris and S-1 charcoal fragments. (Fill) 5 'S-2 Very dense, moist,gray and brown with S-3 GS occasional orange mottling, silty,very gravelly SAND to very sandy GRAVEL. (glacially overridden) 10 S-4 15 S-5 Very dense,moist, brown with orange 20 mottling,silty fine SAND, laminated and layered with Silt partings. S-6 • 25 Very dense,moist, brown with orange mottling,silty,gravelly to very gravelly SAND. (glacially overridden) S-7 30 N Becomes reddish brown with occasional S-8 wet zones where less silty and more m gravelly. 0 35 0 0 U o S-9 Bottom of Boring at 38.3 Feet. Ll Completed 05/07/02. 40 m 0 0 J Z Z K O m 45 1 2 5 10 20 50 100 • Water Content in Percent t/ /R /7A/i/`RoI/.7r: 1.Refer to Figure A-1 for explanation of descriptions and symbols. 2. Soil descriptions and stratum lines are interpretive and actual changes 7748 05102 may be gradual. 3.Groundwater level,if indicated,is at time of drilling(ATD)or for date Figure A-3 specified. Level may vary with time. Boring Log HC-B8 STANDARD PENETRATION LAB Depth RESISTANCE TESTS Soil Descriptions in Feet Approximate Ground Surface Elevation in Feet:28 Sample . Blows per Foot 0 1 2 5 10 20 50 100 1 to 2 inches of Asphalt over very loose to loose,moist,dark brown,slightly silty to S-1 GS silty,gravelly SAND.(FILL) S-2 5 Y A Medium dense, moist with wet zones,gray S-3 B and brown,silty,gravelly SAND. (Like glacially overridden soils) 10 a Very dense, moist,gray and brown, gravelly,silty SAND. (glacially overriddenl) S-4 15 Zone of Gravel. S-5 20 Becomes reddish brown,silty, S-s gravelly SAND with zones of wet,slightly silty, gravelly SAND. 25 S-7 A • Bottom of Boring at 28.4 Feet. a Completed 05/09/02. 30 e m m 0 35 c� X 0 U U S U m 40 a 0 0 J Z Z cc 0 m 45 1 2 5 10 20 50 100 • Water Content in Percent MrI a �/m IZ oWSEJ 1. Refer to Figure A-1 for explanation of descriptions and symbols. 2.Soil descriptions and stratum lines are interpretive and actual changes 7748 05102 may be gradual. 3.Groundwater level,if indicated,is at time of drilling(ATD)or for date Figure A-4 specified. Level may vary with time. Boring Log HC-B9 STANDARD PENETRATION LAB Depth RESISTANCE TESTS Soil Descriptions in Feet Approximate Ground Surface Elevation in Feet: 19 Sample • Blows per Foot 1 2 5 10 20 50 100 Medium dense, moist, brown,slightly silty, 0 very sandy GRAVEL with cobbles. (Pit Run Fill) S-1 5 S-2 Very loose to loose soil based on blow counts, but insufficient recovery to confirm 10 soil type.Anticipated to be similar to soils Q 'S-3 in HC-B10(wet,slightly silty SAND). Q ATD Medium dense,wet, brown and reddish brown, slightly silty,very gravelly SAND. 15 S- • GS 20 S-5 • 2 inches of Gravel encountered in bottom of sampler. 25 A Medium dense to dense, moist to wet, S-6 e reddish brown,silty to very silty SAND. (Like glacially overridden soils) 30 S-7 II N Q I O I c I 35 gg a o Bottom of Boring at 36.5 Feet. Completed 05/09/02. x a m 40 P n C9 O t7 z 0 0 m 45 1 2 5 10 20 50 100 • Water Content in Percent MIME u 1.Refer to Figure A-1 for explanation of descriptions and symbols. 2.Soil descriptions and stratum lines are interpretive and actual changes HA. fCR0WSER may be gradual. 3.Groundwater level,if indicated,is at time of drilling(ATD)or for date 7748 05/02 specified. Level may vary with time. 4.11.0 foot water level measured inside auger after drilling and water Figure A-5 stabilized. 5.Hand auger to 4 feet to check for utilities. Boring Log HC-B 10 STANDARD PENETRATION LAB D�� RESISTANCE TESTS Soil Descriptions i Approximate Ground Surface Elevation in Feet: 17 Sample • Blows per Foot 0 1 2 5 10 20 50 100 Medium dense, moist,brown, slightly silty, S-1 very sandy GRAVEL with cobbles. (Pit-Run Fill) S-2 5 S-3 Medium dense to dense,wet, brown and reddish brown,gravelly SAND with trace Silt. 10 q •S-4 ATD 15 S-5 • Becomes gray and brown SAND. 20 S-6 • GS 25 S-7A 5-78 6-inch-thick layer of moist to wet,brown S-7 and gray,gravelly silty to very silty SAND with silt zones.(Like glacially overridden soils) 30 S-s n • Stiff, moist,gray and brown with orange B mottling,silty,sandy to very sandy CLAY N with occasional trace Gravel. 0 m 0 35 EL S-9 AL Ir O U U = Very dense, moist to wet, reddish brown, silty,gravelly SAND. (glacially overridden) m 40 e S-10 • Bottom of Boring at 41.4 Feet. oJ Completed 05/08/02. 0 Z_ 0 m 145 1 2 5 10 20 50 100 • Water Content in Percent 1.Refer to Figure A-1 for explanation of descriptions and symbols. '�L/Li/L./i�IIJIJI 2.Soil descriptions and stratum lines are interpretive and actual changes may be gradual. 3.Groundwater level,if indicated,is at time of drilling(ATD)or for date 7748 05102 specified. Level may vary with time. Figure A-6 4.7 foot water level measured inside auger after drilling and water stabilized. g 5.Hand auger to 4 feet to check for utilities. APPENDIX B LABORATORY TESTING PROGRAM Hart Crowser 7748 August 19,2002 APPENDIX B LABORATORY TESTING PROGRAM A laboratory testing program was performed for this study to evaluate the basic index and geotechnical engineering properties of the site soils. The tests performed and the procedures followed are outlined below. Soil Classification Field Observation and Laboratory Analysis. Soil samples from the explorations were visually classified in the field and then taken to our laboratory where the classifications were verified in a relatively controlled laboratory environment. Field and laboratory observations include density/consistency, moisture condition, and grain size and plasticity estimates. The classifications of selected samples were checked by grain size analyses. Classifications were made in general accordance with the Unified Soil Classification (USC) System, ASTM D 2487, as presented on Figure B-1. Water Content Determinations Water contents were determined for most samples recovered in the explorations in general accordance with ASTM D 2216, as soon as possible following their arrival in our laboratory. The results of these tests are plotted at the respective sample depth on the exploration logs. In addition, water contents are routinely determined for samples subjected to other testing. These are also presented on the exploration logs. Grain Size Analysis (GS) Grain size distribution was analyzed on representative samples in general accordance with ASTM D 422. Wet sieve analysis was used to determine the size distribution greater than the U.S. No. 200 mesh sieve. The results of the tests are presented as curves on Figures B-2 and B-3 plotting percent finer by weight versus grain size. Atterberg Limits (AL) We determined Atterberg limits for one fine-grained soil sample. The liquid limit and plastic limit were determined in general accordance with ASTM D 4318. The results of the Atterberg limits analyses and the plasticity characteristics are summarized in the Liquid and Plastic Limits Test Report, Figure B-4. This relates Hart Crowser Page B-1 7748 August ts,2002 the plasticity index (liquid limit minus the plastic limit) to the liquid limit. The results of the Atterberg limits tests are shown graphically on the boring logs. F:\docs\iobs\7748\Alderbrook Resort Report.doc Hart Crowser Page 13-2 7748 August 19.2002 Unified Soil Classification (USC) System Soil Grain Size Number of Mesh per Inch 1 Size of Opening In Inches — (us Standard) Grain Size in Millimetres e� co (D -WC7 N N ?� ^ CD N O m O O O O O 01 O O O O C) O O O O N O (0 O of IA M V N O (D N O O 0 0 O O O O O m (D O (n N m (D R n/ N CD (D R M N CD to < n N N O co (D a V) N O O O O O . 0 CDO O O Grain Size in Millimetres COBBLES GRAVEL SAND SILT and CLAY Coarse-Grained Soils Fine-Grained Soils Coarse-Grained Soils GW GP GM GC SW SP \ SM 7 S C Clean GRAVEL<5%fines GRAVEL with>12%fines Clean SAND<5%fines SAND with>12%fines GRAVEL>50%coarse fraction larger than No.4 SAND>50%coarse fraction smaller than No.4 Coarse-Grained Soils>50%larger than No.200 sieve De0 >4 for G W (D30)2 G W and S W' >6 for S W & 1< i <3 G P and S P Clean GRAVEL or SAND not meeting -- 10, D10 X D60i requirements for G W and S W G M and S M Atterberg limits below A line with PI <4 G C and S C Atterberg limits above A Line with PI>7 Coarse-grained soils with percentage of fines between 5 and 12 are considered borderline cases requiring use of dual symbols. D10,D301 and Da0 are the particles diameter of which 10,30,and 60 percent,respectively,of the soil weight are finer. Fine-Grained Soils _ ML — CL OL MH CH OH Pt SILT CLAY Organic SILT CLAY Organic Highly Organic Soils with Liquid Limit<50% Soils with Liquid Limit>50% Soils I Fine-Grained Soils>50%smaller than No.200 sieve 60 60 50 C H 50 ,x 40 40 CL e r 30 P` 30 N a20 M H o r 0 H 20 10 C L - M L M L 10 or O L 0 0 10 20 30 40 50 60 70 80 90 0100 Liquid Limit tI an HC Standards%Standard Repot Figures/Grain Size(e-1).CDR 7748 8102 Figure B-1 PARTICLE SIZE DISTRIBUTION TEST REPORT gg gg gg gg u n 100 8 70 W 60 _Z U- Z �50 Z W U o= W 40 30 i 20 10 0 200 100 10 1 0.1 0.01 0.001 GRAIN SIZE- mm % GRAVEL %SAND % FINES CRS. FINE CRS. MEDIUM FINE SILT CLAY 01 0.0 24.9 28.7 11.8 13.6 12.4 8.6 ❑ 0.0 1 13.7 30.3 17.3 17.9 8.2 12.6 Ll 0.0 6.3 40.0 15.6 14.3 10.6 13.2 LL PI D85 D60 D50 D30 D15 1310 Cc Cu cl 25.0 12.1 5.70 1.14 0.250 0.113 0.96 107.63 0 18.1 5.89 3.52 1.12 0.154 Ll 12.4 1 6.46 3.93 0.871 0.119 MATERIAL DESCRIPTION USCS NAT. MOIST. o Slightly silty,very sandy GRAVEL GP-GM 5% ❑ Silty,very sandy GRAVEL GM 14% o Silty,very sandv GRAVEL GM 7% Remarks: Project: Alderbrook o Entire sample used ❑ Small sample size Client: o Small sample size o Source: HC-B6 Sample No.: S-2 ❑ Source: HC-B6 Sample No.: S-8 o Source: HC-B7 Sample No.: S-3 A --- V 7748 5/22/2002 H1.WCROVVSClt Figure No. B-2 PARTICLE SIZE DISTRIBUTION TEST REPORT C � � 100 so a0 70 W 60 Z t 1: - w w 40 CL 30 20 - 10 II 0 I 200 100 10 1 0.1 0.01 0.001 GRAIN SIZE - mm + 3" GRAVEL % SAND % FINES CRS. FINE CRS. MEDIUM FINE SILT CLAY 01 0.0 16.7 37.3 10.8 11.4 10.4 13.4 0 0.0 0.0 33.9 13.0 26.6 19.8 6.7 0 1 0.0 0.0 26.8 14.4 1 29.7 1 25.0 1 4.1 LL PI I D85 D60 D50 D30 D15 D10 Cc Cu 0 19.7 9.67 6.29 1.04 0.113 1:1 9.85 3.36 1.52 0.489 0.257 0.171 0.42 19.61 8.91 2.16 1 1.10 0.437 0.278 0.224 0.40 9.64 MATERIAL DESCRIPTION USCS NAT. MOIST. 0 Silty,very sandy GRAVEL GM 7% ❑ Slightly silty,very gravelly SAND SP-SM 17% o Gravelly SAND SP 17% Remarks: Project: Alderbrook 0 Small sample size ❑ Client: 0 0 Source: HC-B8 Sample No.: S-1 ❑ Source: HC-139 Sample No.: S-4 o Source: HC-B10 Sample No.: S-6 A V 7748 5/22/2002 Figure No.B-3 LIQUID AND PLASTIC LIMITS TEST REPORT 60 Dashed line indicates the approximate upper limit boundary for natural soils / O� sa / / G 40 ' x , W o / z , F 30 20 � O O 10 4 _ ML or OL MH or OH 10 30 50 70 90 110 LIQUID LIMIT Location+ Description LL PL PI -200 uscs • Source:HC-B 10 Sample No.: S-9 Lean CLAY 45 23 22 CL Remarks: Project: Alderbrook • Client: Location: A V 7748 5/22/2002 M. WCROWS ME Figure No. B-4