Geotechnical & Engineering Consultants

November 11, 2014 PanGEO Project No. 14-054

Mr. Daniel Stoner Parkstone Properties PO Box 77682 Seattle, Washington 98177

Subject: Geotechnical Report Proposed Cubix Apartments 1008 North 109th Street, Seattle, Washington

Dear Mr. Stoner: As requested, PanGEO, Inc. is pleased to present this report to assist the project team with the design and construction of the proposed Cubix Apartments, a 93-Unit Apartment Building at 1008 North 109th Street in Seattle, Washington. In preparing this report, we reviewed the logs from three previously completed test borings at the site and conducted our engineering analyses. In summary, the site is underlain by localized areas of fill ranging up to nine feet thick. Underlying the fill is loose to medium dense and dense and gravelly sand. In our opinion the site may be developed generally as planned. Building support can be provided using a combination of conventional footings bearing on the native or pin pile foundations extending through the existing fill and loose soils and bearing in the underlying dense to very dense soils. We appreciate the opportunity to be of service. Should you have any questions, please do not hesitate to call. Sincerely,

Siew L. Tan, P.E. Principal Geotechnical Engineer

______3213 Eastlake Avenue East, Suite B Seattle, WA 98102 T. (206) 262-0370 F. (206) 262-0374

TABLE OF CONTENTS Section Page 1.0 GENERAL ...... 1 2.0 SITE AND PROJECT DESCRIPTION ...... 1 3.0 SUBSURFACE CONDITIONS ...... 2 3.1 SITE ...... 2 3.2 CONDITIONS...... 3 3.4 GROUNDWATER ...... 3 4.0 GEOTECHNICAL RECOMMENDATIONS ...... 4 4.1 SEISMIC DESIGN PARAMETERS ...... 4 4.2 BUILDING FOUNDATIONS ...... 4 4.2.1 Conventional Footings ...... 5 4.2.2 Pin Pile Foundations ...... 6 4.2.3 Perimeter Footing Drains ...... 9 4.3 FLOORS SLABS ...... 9 4.4 DESIGN PARAMETERS ...... 10 4.4.1 Surcharge ...... 10 4.4.2 Lateral Resistance ...... 10 4.4.3 Wall Drainage ...... 11 4.4.4 Wall Backfill...... 11 4.5 PERMANENT AND FILL SLOPES ...... 11 5.0 EARTHWORK CONSIDERATIONS ...... 12 5.1 TEMPORARY EXCAVATIONS ...... 12 5.2 STRUCTURAL FILL AND COMPACTION ...... 12 5.3 MATERIAL REUSE ...... 13 5.4 WET WEATHER CONSTRUCTION ...... 13 5.5 EROSION CONSIDERATIONS ...... 14 6.0 ADDITIONAL SERVICES ...... 14 7.0 CLOSURE ...... 14 8.0 REFERENCES ...... 17

ATTACHMENTS: Figure 1 Vicinity Map Figure 2 Site and Exploration Location Plan Appendix A Previous Boring Logs (Borings B-1 through B-3)

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GEOTECHNICAL REPORT PROPOSED CUBIX APARTMENTS 1008 NORTH 109TH STREET SEATTLE, WASHINGTON

1.0 GENERAL As requested, PanGEO, Inc. is pleased to present this geotechnical report to assist the project team with the design and construction of the proposed Cubix Apartments, a 93- Unit Apartment development located at 1008 North 109th Street in Seattle, Washington. Our scope of services included reviewing readily available geologic and geotechnical data, reviewing the logs from three previously-drilled borings at the site, conducting a site reconnaissance, and preparing this report containing our recommendations.

2.0 SITE AND PROJECT DESCRIPTION The subject site comprises an undeveloped lot located at 1008 Northeast 109th Street in Seattle, Washington. The project site is approximately as shown on Figure 1, Vicinity Map. The rectangular-shaped site has a total area of 14,107 square feet. The layout of the site is shown on Figure 2. The site is bordered to the north by one-story light manufacturing buildings, to the east by a retail building, to the south by North 109th Street, and to the west by Whitman Avenue North.

The site slopes down gently from west to east, with about four feet of elevation change across the site. However, in the central portion of the site is a 6- to 10-foot high soil stockpile. The stockpile has side slopes of 30 to 50 percent. The soil stockpile will be removed to make way for the proposed Plate 1: View of site from southwest looking to the west. Site development. contains a stockpile of fill, visible in central portion of photo. Plates 1 (right) and 2 (following page) illustrate the general site conditions.

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

It is planned to develop the site with an apartment building. The proposed building will be four stories in height with a partial basement level. The approximate footprints of the proposed building and basement are indicated on Figure 2. We anticipate the lower level of the building will be of concrete construction, with the upper levels of wood frame construction.

The ground floor of the building will be constructed at or near existing site grades. The basement excavation will extend to a depth of about 9 feet below existing . The base of the excavation will extend to within 16½ feet of the north property line and 22 feet from the east property line, 16½ feet from North 109th Street and about 75 feet from the west property line. It is Plate 2: View from southeast portion of site planned to accomplish the basement toward west. excavation as a conventional open cut with temporary slopes. The conclusions and recommendations in this report are based on our understanding of the proposed development, which is in turn based on the project information provided. If the above project description is incorrect, or the project information changes, we should be consulted to review the recommendations contained in this study and make modifications, if needed. In any case PanGEO should be retained to provide a review of the final design to confirm that our geotechnical recommendations have been correctly interpreted and adequately implemented in the construction documents.

3.0 SUBSURFACE CONDITIONS

3.1 SITE GEOLOGY Based on review of The Geologic Map of Seattle – a Progress Report (Troost, et. al. 2005), the project site is underlain by recessional outwash – Geologic Map Unit Qvr. Recessional outwash consists of a stratified , sand, and cobbles deposited by meltwater streams during the retreat of the Vashon Stade of the Frasier Glaciation. This unit is typically loose to dense.

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

3.2 SOIL CONDITIONS In preparing this study, we reviewed the logs from three borings previously drilled at the site (Geotech Consultants, 2002). The approximate locations of the borings are shown on Figure 2. The borings extended to a maximum depth of 31½ feet below grade. The previous borings were drilled before the fill stockpile in the central portion of the site was placed at the site and do not reflect the condition of the stockpile fill. The following is a generalized description of the soils encountered in the borings: : At the location of Boring B-2, a 6-inch thick topsoil horizon was encountered. Fill: At the locations of Borings B-1 and B-3, located near the east end of the site, a surficial layer of fill was encountered. The fill was about 9 feet thick in B-1, on the north side of the proposed basement, and about 7 feet thick in B-3, near the southeast corner of the proposed basement. The fill generally consisted of loose fine sand with a trace of gravel. The contact between the fill and native soils was characterized by a buried topsoil horizon at the location of Boring B-3. Recessional Outwash (Qvr): Underlying the topsoil in Boring B-2 and the fill in Borings B-1 and B-3 is loose to medium dense sand and gravelly sand deposit containing varying amounts of silt. The sand graded to dense to very dense at 10 to 20 feet below grade. This soil is consistent with the description of the recessional outwash deposit.

3.3 GROUNDWATER Groundwater was not encountered at the reviewed boring locations to the maximum depth explored – 31½ feet below grade. As such, we would not anticipate groundwater seepage will result in significant construction related issues. However, groundwater levels and seepage rates will fluctuate depending on the season, amount of rainfall, surface water runoff, and other factors. Generally, the water level is higher and seepage rates are greater in the wetter, winter months (typically October through May).

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

4.0 GEOTECHNICAL RECOMMENDATIONS

4.1 SEISMIC DESIGN PARAMETERS The 2012 International Building Code (IBC) seismic design section provides a basis for seismic design of structures. Table 1 below provides seismic design parameters for the site that are in conformance with the 2012 IBC, which specifies a design earthquake having a 2% probability of occurrence in 50 years (return interval of 2,475 years), and the 2008 USGS maps. Table 1 – Seismic Design Parameters

Design Spectral Spectral Spectral Site Control Periods Response Acceleration Acceleration Coefficients [sec.] Site Class at 0.2 sec. [g] at 1.0 sec. [g] Parameters

SS S1 Fa Fv SDS SD1 TO TS

D 1.264 0.493 1.000 1.507 0.853 0.495 0.116 0.580

The spectral response accelerations were obtained from the USGS Earthquake Hazards Program Interpolated Probabilistic Ground Motion website (2008 data) for the project latitude and longitude. Liquefaction Potential: Liquefaction is a process that can occur when soils lose for short periods of time during a seismic event. Ground shaking of sufficient strength and duration results in the loss of grain-to-grain contact and an increase in , causing the soil to behave as a fluid. Soils with a potential for liquefaction are typically cohesionless, predominately silt and sand sized, must be loose, and be below the groundwater table. The site is predominantly underlain by fill overlying loose to very dense sand and gravelly sand without a defined groundwater table. Based on these conditions, in our opinion the liquefaction potential of the site is negligible and design considerations related to are not necessary for this project.

4.2 BUILDING FOUNDATIONS Based on the subsurface conditions encountered at the site and our understanding of the planned development, it is our opinion the proposed apartment building may be

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014 supported on a combination of a conventional spread and continuous footing system and pin pile foundation system. In our opinion the conventional footings can be used in the basement area and the west half of the building. A pin pile foundation should be used to support the east half, at-grade portion of the building. For planning purposes, we recommend assuming a transition from conventional footings to pin pile foundation at approximately the mid-point along the long axis of the building. The actual transition will depend on the subsurface conditions encountered during site clearing and . It should be noted that, localized footing over-excavation may be needed to reach the competent native bearing soils.

4.2.1 Conventional Footings Conventional spread and continuous footings may be used for the west half of the building and the basement. The footings should bear on the medium dense to dense undisturbed native soil that should be encountered at the construction elevation or on properly compacted structural fill placed on undisturbed native soil. Exterior foundation elements should be placed at a minimum depth of 18 inches below final exterior grade. Interior spread foundations should be placed at a minimum depth of 12 inches below the top of concrete slabs. We recommend a maximum allowable soil bearing pressure of 3,000 pounds per square foot (psf) be used to size the footings. In the basement area, where foundation elements will be more than 9 feet below existing grade, the maximum allowable soil bearing pressure may be increased to 5,000 psf. The recommended allowable bearing pressure is for dead plus live loads. For allowable stress design, the recommended bearing pressure may be increased by one-third for transient loading, such as wind or seismic forces. Continuous and individual spread footings should have minimum widths of 18 and 24 inches, respectively.

Footings designed and constructed in accordance with the above recommendations should experience total settlement of less than one inch and differential settlement of less than ½ inch. Most of the anticipated settlement should occur during construction as dead loads are applied. Lateral Resistance – Lateral loads on the structure may be resisted by passive earth pressure developed against the embedded portion of the foundation system and by

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014 frictional resistance between the bottom of the foundation and the supporting subgrade soils. For footings bearing on the medium dense to very dense silty sand with gravel, a frictional coefficient of 0.35 may be used to evaluate sliding resistance developed between the concrete and the subgrade soil. Passive soil resistance may be calculated using an equivalent fluid weight of 350 pcf, assuming foundations are backfilled with structural fill. The above values include a factor of safety of 1.5. Unless covered by pavements or slabs, the passive resistance in the upper 12 inches of soil should be neglected.

Footing Subgrade Preparation – All footing subgrades should be in a dense condition prior to setting forms and placing reinforcing steel. Any loose or softened soil should be removed from the footing excavations. The adequacy of the footing subgrade soils should be verified by a representative of PanGEO, prior to placing forms or rebar.

4.2.2 Pin Pile Foundations Based on the presence of loose soils extending to a depth of 8 to 10 feet below grade in the east portion of the site, we recommend supporting the east half of the building (except the basement) on driven pin piles. We have provided recommendations for three-, four-, and six-inch diameter piles. The structural engineer should evaluate the pile sizing and spacing based on the anticipated loads. The piles should consist of schedule 40 galvanized steel pipe and should meet the criteria for ASTM A-53 Grade “A” pipe. In order to achieve their allowable capacities, the piles should be driven to the refusal criteria specified in Table 2, following page. The pin piles are typically provided in manageable lengths with straight cut ends. As each length is driven into the ground, additional lengths can be connected with compression fitted sleeve couplers, see Plate 4, following page. We discourage welding of pipe joints, particularly when galvanized pipe is used, as we have frequently observed welds broken during driving.

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

Table 2 - Pin Pile Driving and Refusal Criteria

Pile Hammer Size Refusal Criteria Allowable Diameter (pounds) Pile Capacity

3-Inch 850 Less than one inch of penetration for ten 6 tons seconds of continuous driving at one thousand blows per minute, over three cycles.

4-Inch 850 Less than one inch of penetration for ten 10 tons seconds of continuous driving at one thousand blows per minute, over three cycles.

6-Inch 850 Less than one inch of penetration for ten 20 tons seconds of continuous driving at one thousand blows per minute, over three cycles.

Plate 4: Detail of compression fitted sleeve coupler Courtesy of McDowell Pile King, Kent, WA

Lateral Forces: Due to the slenderness of pin piles, the lateral capacity of vertical pin piles should be ignored in design calculations. Some resistance to lateral loads may be accomplished by battering the piles to a slope of 3H:12V (Horizontal:Vertical), or

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014 steeper. In addition, lateral forces from wind or seismic loading may be resisted by the passive earth pressures acting against the pile caps. Passive resistance values may be determined using an equivalent fluid weight of 350 pounds per cubic foot (pcf). This value includes a safety factor of about 1.5 assuming that properly compacted granular fill will be placed adjacent to and surrounding the pile caps and grade beams, and extend a horizontal distance equal to 2 times the height of the pile caps. resistance at the base of pile-supporting foundation elements should be ignored in design. Estimated Pile Length: We anticipate the piles to achieve refusal in the dense to very dense sand and gravelly sand encountered in the previous explorations. The required pile length in order to develop the recommended pile capacity is expected to vary across the footprint of the structure, depending on the actual driving conditions encountered. For planning and cost estimating purposes, and based on our experience in this area, it is our opinion that an average pile length of about 25 feet is an appropriate assumption. However, the actual pile length will depend on meeting the refusal criteria previously provided in provided in Table 2. Obstructions: Obstructions may be encountered during the pile installation. Where possible, the obstructions should be removed by pre-drilling or excavating to facilitate the pile driving. If obstructions cannot be removed, the structural engineer of record should be notified to revise the pile layout to accommodate moving the piles. Pile Installation Monitoring: The quality of a pin pile foundation is dependent, in part, on the experience and professionalism of the installation company. We recommend that a company with personnel experienced in the successful installation of pin piles be selected to install the piles. As it is not possible to observe the completed pile below the ground, judgment and experience must be used as the basis for determining the acceptability of a pile. Therefore, all piles should be installed under the full-time observation of a representative of PanGEO. This will allow us to fully evaluate the contractor's operation, collect and interpret the installation data, and verify bearing stratum elevations. Furthermore, we will also understand the implications of variations from normal procedures with respect to the design criteria. The contractor's equipment and procedures should be reviewed by PanGEO before the start of construction.

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

Load Testing: The Seattle DPD requires on pin piles. The load testing should be performed in general accordance with the Quick Method under ASTM D-1143 Standard Test Methods for Deep Foundations Under Static Axial Compressive Load. DPD requires load testing be performed on 3 percent of the piles with a minimum of 1 test and a maximum of 5 tests per project. A representative from PanGEO should observe and monitor the load test.

4.2.3 Perimeter Footing Drains Footing drains should be installed around the perimeter of the building, at or just below the invert of the footings. Under no circumstances should roof downspout drain lines be connected to the footing drain systems. Roof downspouts must be separately tightlined to appropriate discharge locations. Cleanouts should be installed at strategic locations to allow for periodic maintenance of the footing drain and downspout tightline systems.

4.3 FLOORS SLABS The floor slabs for the proposed building may be constructed using conventional concrete slab-on-grade floor construction. The floor slab should be supported on competent native soil or on structural fill. Any over-excavations, if needed, should be backfilled with structural fill. Interior concrete slab-on-grade floors should be underlain by a capillary break consisting of at least of 4 inches of pea gravel or compacted ¾-inch, clean crushed rock (less than 3 percent fines). The capillary break material should meet the gradational requirements provided in Table 3, below. Table 3 – Capillary Break Gradation

Sieve Size Percent Passing

¾-inch 100 No. 4 0 – 10 No. 100 0 – 5 No. 200 0 – 3 The capillary break should be placed on the subgrade that has been compacted to a dense and unyielding condition.

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

A 10-mil polyethylene vapor barrier should also be placed directly below the slab. Construction joints should be incorporated into the floor slab to control cracking.

4.4 RETAINING WALL DESIGN PARAMETERS Cast-in-place concrete retaining and basement walls should be designed to resist the lateral earth pressures exerted by the soils behind the wall. Proper drainage provisions should also be provided behind the walls to intercept and remove groundwater that may be present behind the wall.

Cantilever walls should be designed for an equivalent fluid pressure of 35 pcf for a level backfill condition and assuming the walls are free to rotate. If the walls are restrained at the top from free movement, such as basement walls with a floor diaphragm, an equivalent fluid pressure of 45 pcf should be used for a level backfill condition behind the walls. Permanent walls should be designed for an additional uniform lateral pressure of 7H psf for seismic loading, where H corresponds to the height of the buried depth of the wall. The recommended lateral pressures assume that the backfill behind the walls consists of a free draining and properly compacted fill with adequate drainage provisions.

4.4.1 Surcharge Surcharge loads, where present, should also be included in the design of retaining walls. We recommend that a lateral load coefficient of 0.3 be used to compute the lateral pressure on the wall face resulting from surcharge loads located within a horizontal distance of one-half the wall height.

4.4.2 Lateral Resistance Lateral forces from seismic loading and unbalanced lateral earth pressures may be resisted by a combination of passive earth pressures acting against the embedded portions of the foundations and by friction acting on the base of the wall foundation. Passive resistance values may be determined using an equivalent fluid weight of 350 pcf. This value includes a factor of safety of 1.5, assuming the footing is backfilled with structural fill. A friction coefficient of 0.35 may be used to determine the frictional resistance at the base of conventional footings. The coefficient includes a factor of safety of 1.5.

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

Frictional resistance at the base of pile-supported foundation elements should be ignored in design.

4.4.3 Wall Drainage Provisions for wall drainage should consist of a 4-inch diameter perforated drainpipe placed behind and at the base of the wall footings, embedded in 12 to 18 inches of clean crushed rock or pea gravel wrapped with a layer of filter fabric. A minimum 18-inch wide zone of free draining granular soils (i.e. pea gravel or washed rock) is recommended to be placed adjacent to the wall for the full height of the wall. Alternatively, a composite drainage material, such as Miradrain 6000, may be used in lieu of the clean crushed rock or pea gravel. The drainpipe at the base of the wall should be graded to direct water to a suitable outlet.

4.4.4 Wall Backfill Wall backfill should consist of imported, free draining granular material, such as Seattle Type 17 or a soil meeting the requirements of Gravel Borrow as defined in Section 9- 03.14(1) of the WSDOT Standard Specifications for , Bridge, and Municipal Construction (WSDOT 2014). In areas where space is limited between the wall and the face of excavation, pea gravel may be used as backfill without compaction. In our opinion, the predominately silty sand and silt soils underlying the site are not suitable for use as wall backfill. Wall backfill should be moisture conditioned to within about 3 percent of optimum moisture content, placed in loose, horizontal lifts less than 8 inches in thickness, and systematically compacted to a dense and relatively unyielding condition and to at least 95 percent of the maximum dry density, as determined using test method ASTM D-1557 (Modified Proctor). Within 5 feet of the wall, the backfill should be compacted with hand-operated equipment to at least 90 percent of the maximum dry density.

4.5 PERMANENT SLOPES Based on the anticipated soil that will be exposed in the planned excavation, we recommend permanent cut and fill slopes be constructed no steeper than 2H:1V (Horizontal:Vertical).

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

5.0 EARTHWORK CONSIDERATIONS

5.1 TEMPORARY EXCAVATIONS In order to achieve construction subgrade elevations an excavation extending to a depth of about 10 feet deep is planned for the east central portion of the site. The base of the excavation will extend to within 16½ feet of the north property line, 22 feet from the east property line, 16½ feet from North 109th Street to the south, and about 75 feet from the west property line. Temporary excavations should be constructed in accordance with Part N of the WAC (Washington Administrative Code) 296-155. The contractor is responsible for maintaining safe excavation slopes and/or shoring. For planning purposes, temporary excavations may be sloped as steep as 1.5H:1V (Horizontal:Vertical). Where feasible, an L-shaped footing can be used to reduce the extent of the temporary excavations. Temporary excavations should be evaluated in the field during construction based on actual observed soil conditions. If seepage is encountered, excavation slope inclinations may need to be reduced. During wet weather, the cut slopes may need to be flattened to reduce potential erosion or should be covered with plastic sheeting.

5.2 STRUCTURAL FILL AND COMPACTION Structural fill, if needed, should consist of City of Seattle Type 17, WSDOT Section 9- 03.9(3) Crushed Surfacing Base Course (WSDOT 2014), or an approved similar material. Structural fill should be moisture conditioned to within about 3 percent of optimum moisture content, placed in loose, horizontal lifts less than 8 inches in thickness, and compacted to at least 95 percent maximum density, determined using ASTM D-1557 (Modified Proctor). The procedure to achieve proper density of a compacted fill depends on the size and type of compaction equipment, the number of passes, thickness of the lifts being compacted, and certain soil properties. If the excavation to be backfilled is constricted and limits the use of , smaller equipment can be used, but the lift thickness will need to be reduced to achieve the required relative compaction. Generally, loosely compacted soils are a result of poor construction technique or improper moisture content. Soils with high fines contents are particularly susceptible to

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014 becoming too wet and coarse-grained materials easily become too dry, for proper compaction. Silty or clayey soils with a moisture content too high for adequate compaction should be dried as necessary, or moisture conditioned by mixing with drier materials, or other methods.

5.3 MATERIAL REUSE The native soils underlying the site are slightly moisture sensitive, and may become disturbed and soft when exposed to inclement weather conditions. If it is planned to use the native soil as structural fill, the excavated soil should be stockpiled and protected with plastic sheeting to prevent it from becoming saturated by precipitation or runoff.

5.4 WET WEATHER CONSTRUCTION General recommendations relative to earthwork performed in wet weather or in wet conditions are presented below. The following procedures are best management practices recommended for use in wet weather construction:  Earthwork should be performed in small areas to minimize subgrade exposure to wet weather. Excavation or the removal of unsuitable soil should be followed promptly by the placement and compaction of clean structural fill. The size and type of construction equipment used may have to be limited to prevent soil disturbance.  During wet weather, the allowable fines content of the structural fill should be reduced to no more than 5 percent by weight based on the portion passing the 0.75-inch sieve. The fines should be non-plastic.

 The ground surface within the construction area should be graded to promote run-off of surface water and to prevent the ponding of water.  silt fences should be installed at strategic locations around the site to control erosion and the movement of soil.  Excavation slopes and soils stockpiled on site should be covered with plastic sheeting.

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

5.5 EROSION CONSIDERATIONS Surface runoff can be controlled during construction by careful grading practices. Temporary may require the use of silt fence on the downhill side of the site to prevent water from leaving the site and potential storm water detention to trap sand and silt before the water is discharged to a suitable outlet. All collected water should be directed under control to a positive and permanent discharge system. Permanent control of surface water should be incorporated in the final grading design. Adequate surface gradients and drainage systems should be incorporated into the design such that surface runoff is collected and directed away from the structure to a suitable outlet. Potential issues associated with erosion may also be reduced by establishing vegetation within disturbed areas immediately following grading operations.

6.0 ADDITIONAL SERVICES To confirm that our recommendations are properly incorporated into the design and construction of the proposed building, PanGEO should be retained to conduct a review of the final project plans and specifications, and to monitor the construction of geotechnical elements. The City of Seattle DPD, as part of the permitting process, will also require geotechnical construction inspection services. PanGEO can provide you a cost estimate for construction monitoring services at a later date.

7.0 CLOSURE We have prepared this report for Parkstone Properties and the project design team. Recommendations contained in this report are based on a site reconnaissance, a subsurface exploration program, review of pertinent subsurface information, and our understanding of the project. The study was performed using a mutually agreed-upon scope of services. Variations in soil conditions may exist between the locations of the explorations and the actual conditions underlying the site. The nature and extent of soil variations may not be evident until construction occurs. If any soil conditions are encountered at the site that are different from those described in this report, we should be notified immediately to review the applicability of our recommendations. Additionally, we should also be notified to review the applicability of our recommendations if there are any changes in the project scope.

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

The scope of our work does not include services related to construction safety precautions. Our recommendations are not intended to direct the contractors’ methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. Additionally, the scope of our services specifically excludes the assessment of environmental characteristics, particularly those involving hazardous substances. We are not mold consultants nor are our recommendations to be interpreted as being preventative of mold development. A mold specialist should be consulted for all mold-related issues. This report has been prepared for planning and design purposes for specific application to the proposed project in accordance with the generally accepted standards of local practice at the time this report was written. No warranty, express or implied, is made. This report may be used only by the client and for the purposes stated, within a reasonable time from its issuance. Land use, site conditions (both off and on-site), or other factors including advances in our understanding of applied science, may change over time and could materially affect our findings. Therefore, this report should not be relied upon after 24 months from its issuance. PanGEO should be notified if the project is delayed by more than 24 months from the date of this report so that we may review the applicability of our conclusions considering the time lapse.

It is the client’s responsibility to see that all parties to this project, including the designer, contractor, subcontractors, etc., are made aware of this report in its entirety. The use of information contained in this report for bidding purposes should be done at the contractor’s option and risk. Any party other than the client who wishes to use this report shall notify PanGEO of such intended use and for permission to copy this report. Based on the intended use of the report, PanGEO may require that additional work be performed and that an updated report be reissued. Noncompliance with any of these requirements will release PanGEO from any liability resulting from the use this report.

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

Sincerely, PanGEO, Inc.

Scott D. Dinkelman, LEG, LHG Siew L Tan, P.E. Senior Engineering Geologist Principal Geotechnical Engineer

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Geotechnical Report Proposed Cubix Apartment: 1008 North 109th Street, Seattle, Washington November 11, 2014

8.0 REFERENCES City of Seattle, 2011, Standard Specifications for Road, Bridges, and Municipal Construction. International Code Council, 2012, International Building Code (IBC), 2012. Geotech Consultants, 2002, Study, Proposed Mixed-Use Building, 1002-1008 North 109th Street, Seattle, Washington. Consultant report prepared for Mike Hughes and Laura Sagen, file number JN02173, dated June 24. Troost, K.G., Booth, D. B., Wisher, A. P., Shimmel, S. A., 2005, The Geologic Map of Seattle-A Progress Report, Seattle, Washington – U. S. Geological Survey Open File Report 2005-1252, scale 1:24,000. United States Geological Survey, Earthquake Hazards Program, Interpolated Probabalisitic Ground Motion for the Conterminous 48 States by Latitude and Longitude, 2008 Data, accessed via: http://earthquake.usgs.gov/designmaps/us/application.php WSDOT, 2014, Standard Specifications for Road, Bridge and Municipal Construction, M 41-10.

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SITE

Base Map: Bing Maps

NORTH

Approx. Scale: Not to Scale 11/11/14 (9:06 ) SDD VICINITY MAP file.dat Proposed Cubix Apartments 1008 N. 109th St .grf w/ Seattle, WA file Project No. 14-054 Figure No. 1 Fig 2 - Site and Exploration Plan.grf w/ [file.jpg] 11/11/14 (9:09 ) SDD

B-2 B-1 AURORA AVE N WHITMAN AVE N

B-3

N 109TH ST

B-1 Subject Site Proposed Building Approximate Boring Location, Geotech Consultants, Inc. May 2002 Existing Structures Proposed Basement

NORTH Approx. Scale

02040 SITE AND EXPLORATION PLAN Proposed Cubix Apartment 1008 N. 109th St Seattle, WA Project No.14-054 Figure No. 2

APPENDIX A

PREVIOUS BORING LOGS