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REVIEWED BLD2021-0116+GEO REPORT+1.18.2022_9.09.19_AM+2625689Irerracon &e'o R e p or- -t Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 Prepared for: CA Senior Living Holdings, LLC Chicago, IL Prepared by: Terracon Consultants, Inc. Mountlake Terrace, Washington December 20, 2018 CA Senior Living Holdings, LLC 12345 Street Name Chicago, IL 00000 Attn: Mr. Michael Duggan — Vice President of Development P: (312) 248-2091 E: mduggan@ca-ventures.com Re: Geotechnical Engineering Report Edmonds Senior Living 21200 72nd Ave. W Edmonds, Washington Terracon Project No. 81185173 Dear Mr. Duggan: Irerracon GeoRe ortp We have completed the Geotechnical Engineering services for the above referenced project. This study was performed in general accordance with Terracon Proposal No. P81185173 dated October 22, 2018. This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork and the design and construction of building foundations, floor slabs, and temporary shoring for the proposed project. Additionally, we provide discussion for stormwater infiltration potential. %At- ___.___:_�_ ��_ ____.1..._:�.. �- be of service to you on this project. If you have any questions be of further service, pleas- , ,- ►�� -- 1-1 J -1 1 1- .. .' . - Senior Staff Engineer Terracon Consultants, Inc. 21905 64th Ave. W, Suite 100 Mountlake Terrace, WA 98043 P (425) 771 3304 F (425) 771 3549 www.terracon.com REPORT TOPICS INTRODUCTION............................................................................................................. 1 SITECONDITIONS......................................................................................................... 1 PROJECT DESCRIPTION..............................................................................................2 GEOTECHNICAL CHARACTERIZATION...................................................................... 3 GEOTECHNICAL OVERVIEW....................................................................................... 4 EARTHWORK................................................................................................................. 5 SHALLOW FOUNDATIONS...........................................................................................9 DEWATERING AND SUBSURFACE DRAINAGE....................................................... 11 SEISMIC CONSIDERATIONS......................................................................................12 FLOORSLABS.............................................................................................................13 LATERAL EARTH PRESSURES................................................................................. 14 EXCAVATION DESIGN................................................................................................ 16 STORMWATER MANAGEMENT................................................................................. 18 GENERAL COMMENTS............................................................................................... 19 Note: This report was originally delivered in a web -based format. Orange Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section and clicking on the GeoReport logo will bring you back to this page. For more interactive features, please view your project online at client.terracon.com. ATTACHMENTS EXPLORATION AND TESTING PROCEDURES PHOTOGRAPHY LOG SITE LOCATION AND EXPLORATION PLANS EXPLORATION RESULTS SUPPORTING INFORMATION Note: Refer to each individual Attachment for a listing of contents. Responsive ■ Resourceful ■ Reliable Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 REPORT SUMMARY Topic 1 Project Description Geotechnical Characterization Earthwork Overview Statement 2 1 rerracon GeoReport Approx. 35,000 square foot development for a senior living facility with six -stories above ground and one below. Assumed Max. Column loads: 500 kips Assumed Max. Wall loads: 6 kips per linear foot Assumed Slab -on -grade: 150 pounds per square foot Pavements do not appear to be part of the planned development Existing fill and recessional outwash soils over glacial till: Loose to dense silty sandy and sandy silt with variable gravel to about 15 feet Dense to very dense glacially consolidated soils to at least 26'h feet Cobbles may be present in glacial soils Groundwater was encountered at about 25 feet below ground surface though perched groundwater may be present shallower The planned development will include removal of topsoil, existing fill, and loose recessional soils. As a minimum, topsoil encountered within proposed driveway or sidewalk subgrades should be removed. Dense, glacially consolidated soils are suitable for foundation subgrades Foundation soils are moisture sensitive and may become unstable when exposed to excessive moisture or are disturbed Shallow foundations will be sufficient Allowable bearing pressure (spread and wall footings) _ Shallow Dense, Native Soil: 5,000 Ibs/sq ft Foundations Below -Grade Structures Shoring Design General Comments Expected settlements: < 1 inch total, <'/2 inch differential Detect and remove zones of unsuitable subgrade as noted in earthwork The planned development includes one level of below grade parking therefore temporary shoring is required Temporary shoring using either cantilevered soldier piles or soldier piles with a single row of tiebacks with 4-inch temporary wood lagging This section contains important information about the limitations of this geotechnical 1. If the reader is reviewing this report as a pdf, the topics above can be used to access the appropriate section of the report by simply clicking on the topic itself. 2. This summary is for convenience only. It should be used in conjunction with the entire report for design Responsive ■ Resourceful ■ Reliable Geotechnical Engineering Report Edmonds Senior Living 21200 72nd Ave. W Edmonds, Washington Terracon Project No. 81185173 December 20, 2018 INTRODUCTION This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed Edmonds Senior Living project to be located at 21200 72nd Ave. W in Edmonds, Washington. The purpose of these services is to provide information and geotechnical engineering recommendations relative to: Subsurface soil conditions Groundwater conditions Site preparation and earthwork Foundation design and construction Floor slab design and construction Seismic considerations and liquefaction Lateral earth pressures Excavation design Stormwater Management The geotechnical engineering scope of services for this project included the advancement of number soil borings to depths ranging from approximately 21 '/2 to 26 '/2 feet below existing site grades, respectively. Maps showing the site and exploration locations are shown in the Site Location and Exploration sections, respectively. The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included on the boring logs and/or as separate graphs in the Exploration Results section of this report. SITE CONDITIONS The following description of site conditions is derived from our site visit in association with the field exploration and our review of publicly available geologic and topographic maps. Item Description The project is located at 21200 72nd Ave. W in Edmonds, Washington. Parcel Information Lot Size: 35, 284 ft2 (0.81 acres) Latitude: 47.8067 Longitude:-122.3307 See Site Location Responsive ■ Resourceful ■ Reliable 1 Geotechnical Engineering Report lrerracon Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 GeoReport Item Description Existing The site is currently developed with a single -story medical office of Improvements approximately 6,641 ftz . The lot includes paved parking areas and drive lanes to the north and east. Current Ground Primarily paved parking with some planting areas around the building. Several Cover large diameter trees are located along the north, south, and east perimeters of the site. Existing Topography The site is gently sloping with elevation of about 282 feet along the northern (Google Earth) property line to about 374 feet to the south. Near -surface soils were generally fill and recessional glacial outwash Geology consisting primarily of loose to medium dense silty sand. Underlying the fill and outwash is dense to very dense, glacially consolidated silty sandy and sandy silt. PROJECT DESCRIPTION Our initial understanding of the project was provided in our proposal, and to the best of our knowledge, has remained unchanged. The understanding in which our assumptions and recommendations are based is as follows: Item Description Email request for proposal as communicated to Terracon by CA Information Provided Senior living facility test fit (no date or title on document) Edmonds development site offering memorandum prepared by Kidder Mathews (no date on document) The project will include demolition of an existing single -story office structure Project Description and development of a multi -story senior living facility with below ground parking. The development appears to include a courtyard area between the wings. The proposed senior living facility development will include one building with Proposed Structure east and west wings constructed to 6 stories above grade (75 feet) with one level of below grade parking (14 feet). Building Construction Wood frame over concrete basement (Assumed) Finished Floor Finished floor elevation is not known at this time Elevation ■ Assumed Max. Column loads: 500 kips Maximum Loads ■ Assumed Max. Wall loads: 6 kips per linear foot ■ Assumed Slab -on -grade: 150 pounds per square foot Grading/Slopes Site grades are not known at this time. Responsive ■ Resourceful ■ Reliable Geotechnical Engineering Report lrerracon Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 GeoReport Item Description Below Grade Structures The project includes one below -grade level (approximately 14 feet) Free -Standing Retaining Walls Retaining walls are not anticipated as part of site development. (Assumed) Pavements Paved areas do not appear to be part of the planned development Estimated Start of Not known at this time Construction GEOTECHNICAL CHARACTERIZATION We have developed a general characterization of the subsurface soil and groundwater conditions based upon our review of the data and our understanding of the geologic setting and planned construction. The following table provides our geotechnical characterization. The geotechnical characterization forms the basis of our geotechnical calculations and evaluation of foundation options. As noted in General Comments, the characterization is based upon widely spaced exploration points across the site, and variations are likely. Stratum Approximate Depth to Bottom of Stratum (feet) Material Description Asphalt/Concrete Approx. 1 '/2 inch asphalt pavement with 2 inch base course light brown to brown, silty sand with 3'/2 to 7'/2 variable gravel content, some woody debris and cobbles (Fill) grayish brown to brown, sand with 10 to 13 silt content, trace gravel (Recessional Glacial Outwash) gray to dark gray and tan, silty sand at least 26'/2 and sandy silt with variable gravel content (Glacial Till) 1. All borings were terminated in this stratum Consistency/Density N/A loose to medium dense medium dense dense to very dense/hard Conditions encountered at each boring location are indicated on the individual boring logs shown in the Exploration Results section and are attached to this report. Stratification boundaries on the boring logs represent the approximate location of changes in soil types; in situ, the transition between materials may be gradual or vary spatially. Responsive ■ Resourceful ■ Reliable Geotechnical Engineering Report lrerracon Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 GeoReport Groundwater Conditions The boreholes were observed while drilling and after completion for the presence and level of groundwater. The water levels observed in the boreholes can be found on the boring logs in Exploration Result! , and are summarized below. WM Boring Number B-1, B-2, B-3 B-4 Approximate Depth to Groundwater while Drilling (feet) Not encountered 20 '/2 1. Below ground surface 2. Groundwater is inferred from change in sample moisture 3. Water not present in borehole following extraction of augers Approximate Depth to Groundwater after Drilling (feet) Not encountered 3 Groundwater was not observed borings B-1, B-2, and B-3 while drilling, and was not observed in any boring after extraction of augers for the short duration the borings could remain open. However, this does not necessarily mean the borings terminated above groundwater, or the water levels summarized above are stable groundwater levels. Due to the low permeability of the soils encountered in the borings, a relatively long period may be necessary for a groundwater level to develop and stabilize in a borehole. Long term observations in piezometers or observation wells sealed from the influence of surface water are often required to define groundwater levels in materials of this type. Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater levels during construction or at other times in the life of the structure may be higher or lower than the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project. GEOTECHNICAL OVERVIEW The proposed development will result in about a 14-foot deep excavation to accommodate one level of below grade parking and the building foundations. Although not directly observed in the surface exploration, perched shallow groundwater is commonly present over dense, glacially consolidated soils and therefore may be present during construction. Construction dewatering may be required during excavation and shoring installation. Additionally, the upper 13 feet of the subsurface consists of primarily loose to medium dense cohesionless soils with the potential for a shallow groundwater table. Therefore, the most cost-effective shoring system is likely a cantilever soldier pile or a soldier pile and single row of tiebacks. An easement for temporary Responsive ■ Resourceful ■ Reliable Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport, tiebacks will be required from the private properties located on the south and west sides of the project and from the City of Edmonds for anchoring in the public right of way to the north and east. The soils anticipated at the base of the excavation are sufficiently dense for shallow foundations. Casting of foundations may be performed directly onto the existing soils, provided care is exercised during construction to minimize disturbance. Due to the appreciable silt content in these soils, the subgrade could become unstable if not protected from excessive foot and construction traffic, especially after precipitation events. Construction dewatering, if needed, should maintain a dry excavation at least two feet below the foundation subgrade. If possible, construction should be performed during the warmer and drier time of the year. If work is performed during the wet months, an increased risk for possible unstable subgrade, and difficult working conditions, persists. Additional site preparation recommendations are provided in the Earthwork section. The Shallow Foundations and Floor Slabs sections address bearing on native soils, or lean mix concrete if overexcavation is required due to disturbance of the subgrade. Groundwater inflow into the excavation is anticipated to be limited to shallow, perched groundwater zones so inflows are anticipated to be low. Existing fill was observed up to 7'/z feet below ground surface, which is shallower than the depth of the planned excavation; therefore, it is not anticipated that excavation for building foundations or the basement floor slab will encounter fill. Sidewalk and pavement subgrades outside the building may be supported on existing fill materials. However, there is an inherent risk for the owner that compressible fill or unsuitable materials within or buried by the fill will not be discovered. This risk of unforeseen conditions cannot be eliminated without completely removing the existing fill but can be reduced by removing the upper foot of fill followed by scarification and recompaction of an additional foot (i.e. total of 2 feet of compacted material below the subgrades). The General Comments section provides an understanding of the report limitations. EARTHWORK Earthwork will include clearing and grubbing, demolition and removal of existing building foundations, and deep excavation to about 14 feet below existing grade, foundation preparation, and utility trenching. The following sections provide recommendations for use in the preparation of specifications for the work. Recommendations include critical quality criteria as necessary to render the site in the state considered in our geotechnical engineering evaluation for foundations, floor slabs, and pavements. Responsive ■ Resourceful ■ Reliable 5 Geotechnical Engineering Report lrerracon Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 GeoReport Site Preparation The subgrade should be proof -rolled with an adequately loaded vehicle or construction equipment. The proof -rolling should be performed under the observation of the Geotechnical Engineer. Areas excessively deflecting under the proof -roll should be delineated and subsequently addressed by the Geotechnical Engineer. Such areas should either be removed or recompacted in place. Excessively wet or dry material should either be removed or moisture conditioned and recompacted. For areas outside the proposed excavation, existing vegetation and root mats should be removed prior to placing fill. Complete stripping of the topsoil should be performed for driveway, sidewalk, and parking areas. Existing Fill As noted in Geotechnical Characterization, the surface explorations encountered existing fill. Within the building footprint, the existing fill will be removed as part of the planned excavation. Sidewalks and driveways that are outside the building footprint will encounter fill at the subgrade elevation. These features can be constructed over existing fill, however, there is an inherent risk for the owner that compressible fill or unsuitable material within or buried by the fill will not be discovered. This risk of unforeseen conditions cannot be eliminated without completely removing the existing fill. If the owner elects to construct sidewalks and driveways over the existing fill, at least one -foot below the planned subgrade elevation should completely stripped followed by proof -rolling for the entire area. Areas of soft or otherwise unsuitable material should be undercut and replaced with either new structural fill or suitable, existing on site materials. All subgrades should be field verified by the Geotechnical Engineer to help identify areas with unstable subgrades. These areas should be removed and replaced with suitable fill or recompacted. Fill Material Types Fill required to achieve design grade should be classified as structural fill and common fill. Structural fill is material used below, or within 10 feet of structures, pavements or constructed slopes. Common fill is material used to achieve grade outside of these areas. Earthen materials used for structural and common fill should meet the following material property requirements: Responsive ■ Resourceful ■ Reliable 6 Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 Fill Type Recommended Materials 9-03.9(1) Ballast 9-03.9(3) Crushed Surfacing Base Course Structural 9-03.12(1)A Gravel Backfill for Foundations Class A Common Fill 9-03.14(1) Gravel Borrow On -site Soils (Stratum 1 and 2) 1 rerracon GeoReport Acceptable Location for Placement Beneath and adjacent to structural slabs, foundations, and pavement subgrades Grade filling, utility trench backfill outside the building foundation 1. WSDOT Standard Specifications 2. Structural and common fill should consist of approved materials free of organic matter and debris. Frozen material should not be used, and fill should not be placed on a frozen subgrade. A sample of each material type should be submitted to the Geotechnical Engineer for evaluation prior to use on this site. May contain local areas of higher fines content that could make this material moisture sensitive. Particles with a nominal diameter greater than about 3 inches should be removed. Section 9-03.14(3) Common Borrow On -site Soils (Stratum 1 and 2) Fill Compaction Requirements Structural and common fill should meet the following compaction requirements. Item Structural Fill Common Fill 8 inches or less in loose thickness when heavy, Maximum Lift self-propelled compaction equipment is used Thickness 4 to 6 inches in loose thickness when hand- Same as Structural fill guided equipment (i.e. jumping jack or plate compactor) is used Minimum Compaction 95% of maximum dry density Same as Structural fill Requirements Water Content Typically within 2/o o of optimum As required to achieve min. Range compaction requirements Maximum density and optimum water content as determined by the modified Proctor test (ASTM D 1557). Utility Trench Backfill All trenches should be wide enough to allow for compaction around the haunches of the pipe, or material such as pea gravel (provided this is allowed by the pipe manufacturer) should be used below the spring line of the pipes to eliminate the need for mechanical compaction in this portion of the trenches. If water is encountered in the excavations, it should be removed prior to fill placement. Responsive ■ Resourceful ■ Reliable 7 Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport, Placement and compaction of recommended materials for utility trench backfill should be in accordance with the recommendations presented herein for Earthwork. In our opinion, the initial lift thickness should not exceed one foot unless recommended by the manufacturer to protect utilities from damage by compacting equipment. Light, hand -operated compaction equipment in conjunction with thinner fill lift thicknesses may be utilized on backfill placed above utilities if damage resulting from heavier compaction equipment is of concern. Flexible connections for utilities that pass through building foundations are recommended to reduce potential stress associated with differential settlement that may occur between the building foundation and the improvements located outside of the building footprint. Earthwork Construction Considerations Upon completion of filling and grading, care should be taken to maintain the subgrade water content prior to construction of floor slabs. Construction traffic over the completed subgrades should be avoided. The base of the excavation should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. Water collecting over, or adjacent to, construction areas should be removed. If the subgrade freezes, desiccates, saturates, or is disturbed, the affected material should be removed, or the materials should be scarified, moisture conditioned, and recompacted, prior to construction. Construction dewatering is discussed in Excavation Design. Construction Observation and Testing The earthwork efforts should be monitored under the observation of the Geotechnical Engineer. Each lift of compacted fill should be tested, evaluated, and reworked as necessary until approved by the Geotechnical Engineer prior to placement of additional lifts. Each lift of fill should be tested for density and water content. In areas of foundation excavations, the bearing subgrade should be evaluated by the Geotechnical Engineer. In the event that unanticipated conditions are encountered, the Geotechnical Engineer should recommend mitigation options. In addition to the documentation of the essential parameters necessary for construction, the continuation of the Geotechnical Engineer into the construction phase of the project provides the continuity to maintain the Geotechnical Engineer's evaluation of subsurface conditions, including assessing variations and associated design changes. Wet Weather Earthwork The foundation soils at the base of the excavation have variable fines content based on our visual observations and lab testing and are considered moisture sensitive. The suitability of soils used Responsive ■ Resourceful ■ Reliable 8 Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport for structural fill depends primarily on their grain -size distribution and moisture content when they are placed. As the fines content (the soil fraction passing the U.S. No. 200 Sieve) increases, soils become more sensitive to small changes in moisture content. Soils containing more than about 5 percent fines (by weight) cannot be consistently compacted to a firm, unyielding condition when the moisture content is more than 2 percentage points above or below optimum. Optimum moisture content is the moisture content at which the maximum dry density for the material is achieved in the laboratory by the ASTM D1557 test procedure. If inclement weather or in situ soil moisture content prevents the use of on -site material as structural fill, we recommend importing granular fill containing less than 5 percent by weight passing the U.S. No. 200 sieve, based on the fraction passing the U.S. No. 4 sieve. Stockpiled soils should be protected with polyethylene sheeting anchored to withstand local wind conditions and preservation of the soil's moisture content. SHALLOW FOUNDATIONS If the site has been prepared in accordance with the requirements noted in Earthwork, the following design parameters are applicable for shallow foundations. Design Parameters — Compressive Loads Description Net allowable bearing pressure ■ Dense/hard, native soil Minimum dimensions Minimum embedment below finished grade 3 Approximate static total settlement from foundation loads for condition specified" Estimated static differential settlement from foundation loads Ultimate passive pressure on native soil Ultimate coefficient of sliding friction Spread Footing 5,000 psf 24 inches 18 inches <1 inch Wall Footing 5,000 psf 18 inches 18 inches <1 inch About 2/3 of total settlement 350 pcf (equivalent fluid unit weight) 0.40 Responsive ■ Resourceful ■ Reliable Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport, Description Spread Footing Wall Footing The maximum net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation. An appropriate factor of safety has been applied. These bearing pressures can be increased by 1/3 for transient loads unless those loads have been factored to account for transient conditions. Assumes that exterior grades are relatively level adjacent to the structure. Values provided are for maximum loads noted in �. For frost protection and to reduce the effects of seasonal moisture variations in the subgrade soils. For perimeter footing and footings beneath unheated areas. For sloping ground, maintain depth below the lowest adjacent exterior grade within 5 horizontal feet of the structure. 4. Differential settlements are as measured over a span of 50 feet. 5. Use of passive earth pressures require the sides of the excavation for the spread footing foundation to be nearly vertical and the concrete placed neat against these vertical faces or that the footing forms be removed and compacted structural fill be placed against the vertical footing face. 6. Passive resistance in the upper 2 feet of the soil profile should be neglected. 7. Can be used to compute sliding resistance where foundations are placed on suitable soil/materials. Should be neglected for foundations subject to net uplift conditions. Foundation Construction Considerations As noted in Earthwork, the footing excavation subgrades should be observed by the Geotechnical Engineer. The base of all foundation excavations should be free of water and loose soil, prior to placing concrete. Concrete should be placed soon after excavating to reduce bearing soil disturbance. Care should be taken to prevent wetting or drying of the bearing materials during construction. Excessively wet or dry material or any loose/disturbed material in the bottom of the footing excavations should be removed or reconditioned before foundation concrete is placed. If unsuitable bearing soils are encountered at the base of the planned footing excavation, or if prepared subgrades become disturbed through construction activities, the excavation should be extended deeper to suitable soils. The excavation can be backfilled to the planned grade through use of lean concrete as illustrated below. DESIC FOOT REC( EXCF LEAN CONCRETE BACKFILL NOTE: EXCAVATIONS ARE SHOWN VERTICAL, HOWEVER, THE SIDEWALLS SHOULD BE SLOPED AS NECESSARY FOR SAFETY Responsive ■ Resourceful ■ Reliable 10 Geotechnical Engineering Report lrerracon Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 GeORepOrt DEWATERING AND SUBSURFACE DRAINAGE We recommend that the walls and parking garage slab are positively drained to collect and convey ground water seepage that may be present. The drainage system should consist of a combination of free -draining structural fill (i.e. material with less than 5 percent passing the No. 200 sieve), wall drainage, footing drains, and a sump collection system if discharge by gravity is not possible. To estimate the steady state flow rate of the under slab and a wall drainage system, further study of groundwater inflows via pump testing and installation of a monitoring wells may be necessary to better estimate the hydraulic conductivity of the foundation soils. For planning purposes, the hydraulic conductivity can be approximated as 10-4 cm per second for the foundation soils, based on particle size analyses. Wall Drainage Basement walls poured flush against the shoring should be provided with drainage by placing full face geocomposite drain against the shoring wall. The geocomposite drain should be tied into the footing drainage system. It is important to provide a good connection between the wall drain and the footing drainage system. The detail of the wall/footing drain connection will depend on the type of shoring, basement wall type, and perimeter footing. Drainage behind walls cast in open excavations can consist of geocomposite drainage as discussed above or a minimum of a 2-foot wide zone of clean sand and gravel fill with less than 5 percent passing the No. 200 sieve. If a moisture -free wall is desired, a water proof barrier, such as plastic or bentonite panels, should be placed over the geocomposite drain prior to pouring or shotcreting the concrete wall. Footing Drains A perimeter footing drain should also be provided and consist of a minimum 4-inch diameter heavy walled perforated PVC pipe or equivalent. We recommend that the footing drains have a minimum slope of 0.25 percent, and that the pipe invert is at least 12-inches below the finish floor slab. The pipe should be bedded in at least 4-inches and surrounded by at least 6-inches, of drainage material consisting of 3/4-inch washed drain rock. We recommend use of nonwoven filter fabric (Mirafi 140N or equivalent) to wrap the entire pipe and rock assembly. Cleanouts are recommended for the footing drain system. Sumps If gravity flow is not possible, the footing and wall drainage system should drain to a sump for pumping. The steady state or long-term groundwater flow rate should be evaluated during construction and the permanent drainage system sized for that flow. If a sump system is used, a backup pump with emergency power is recommended in case of mechanical breakdown. We recommend that the sump and drain pipe clean outs be vented to the atmosphere to prevent the Responsive ■ Resourceful ■ Reliable 11 Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport buildup of hydrostatic pressure below the floor slab in case of mechanical or electrical failure of the sump pumps. Dewatering Considerations Construction dewatering is the responsibility of the contractor, who should maintain the excavation and foundation subgrades in a dry condition. Seepage associated with groundwater may be encountered in the excavation for the below grade parking. Based on the results of the subsurface explorations, active dewatering may not be necessary as groundwater was only encountered at about 20 feet below ground surface for B-4 though zones of perched groundwater are typical in similar geologic media. Further study of groundwater inflows via pump testing and installation of monitoring wells may be necessary to better estimate the hydraulic conductivity of retained soils and potential for shallow groundwater. SEISMIC CONSIDERATIONS The seismic design requirements for buildings and other structures are based on the Seismic Design Category. Site Classification is required to determine the Seismic Design Category for a structure. The Site Classification is based on the upper 100 feet of the site profile defined by a weighted average value of either shear wave velocity, standard penetration resistance, or undrained shear strength in accordance with Section 20.4 of ASCE 7-10. Description IValue 1,2 Site Latitude D3 47.8066 Site Longitude-122.3307 Ss — Short Period Spectral Acceleration, Site Class B 4 1.273 g S,-1-Second Period Spectral Acceleration, Site Class B Fa — Short Period Site Coefficient F„-1-Second Period Site Coefficient4 PGA - ASCE 7-10, Peak Ground Acceleration 0.497 g 1.000 1.503 0.516 g FPCA — Peak Ground Acceleration Site Coefficient 1.000 Seismic site classification in general accordance with the 2015 1 BC, which refers to ASCE 7-10. 2015 IBC requires a site profile extending to a depth of 100 feet for seismic site classification. The site properties below the exploration depth to 100 feet were estimated based on our experience and knowledge of geologic conditions of the general area. Site Class D applies to any profile having (1) soils having an average shear wave velocity of 600 to 1,200 feet per sec, (2) an average N value of 15 to 50, (3) an undrained shear strength of 1,000 to 2,000 psf. These values were obtained using online seismic design maps and tools provided by the USGS (http://earthguake.usgs.gov/hazards/designmgps/). Responsive ■ Resourceful ■ Reliable Geotechnical Engineering Report lrerracon Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 GeORepOrt Surface -Fault Rupture The hazard of damage from onsite fault rupture appears to be low based on review of the Washington Department of Natural Resources Geologic Information Portal available online (https://geologyportal.dnr.wa.gov/#natural hazards) accessed on December 19, 2018. The closest mapped fault is the Southern Whidbey Island fault zone, which is an inferred fault trace, and lies approximately a 1/4 mile to the southwest. Liquefaction Liquefaction is the phenomenon where saturated soils develop high pore water pressures during seismic shaking and lose their strength characteristics. This phenomenon generally occurs in areas of high seismicity, where groundwater is shallow and loose granular soils or relatively non - plastic fine-grained soils are present. Based on the site geology and subsurface groundwater conditions, the risk of liquefaction of the site soils is low for this site during a design level earthquake due to the dense nature of the glacially consolidated soils below the foundation level. FLOOR SLABS Design parameters for floor slabs assume the requirements for Earthwork have been followed. Specific attention should be given to positive drainage away from the structure and. positive drainage of the aggregate base beneath the floor slab. Floor Slab Design Parameters Item Description Floor Slab Support Minimum 6 inches of 9-03.12(4) Gravel Backfill for Drains Compacted to at least 95% of maximum dry density (ASTM D 1557) Estimated Modulus of 160 pounds per square inch per inch (psi/in) for point loads Subgrade Reaction 40 pounds per square inch per inch (psi/in) for all other loading scenarios 1. Floor slabs should be structurally independent of building footings or walls to reduce the possibility of floor slab cracking caused by differential movements between the slab and foundation. 2. Modulus of subgrade reaction is an estimated value based upon our experience with the subgrade condition, the requirements noted in Earthwork, and the floor slab support as noted in this table. 3. WSDOT Standard Specification The use of a vapor retarder is recommended beneath concrete slabs on grade covered with wood, tile, carpet, or other moisture sensitive or impervious coverings, or when the slab will support equipment sensitive to moisture. When conditions warrant the use of a vapor retarder, the slab designer should refer to ACI 302 and/or ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder. Responsive ■ Resourceful ■ Reliable 13 Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport, Saw -cut control joints should be placed in the slab to help control the location and extent of cracking. For additional recommendations refer to the ACI Design Manual. Joints or cracks should be sealed with a water -proof, non -extruding compressible compound specifically recommended for heavy duty concrete pavement and wet environments. Where floor slabs are tied to perimeter walls or turn -down slabs to meet structural or other construction objectives, our experience indicates differential movement between the walls and slabs will likely be observed in adjacent slab expansion joints or floor slab cracks beyond the length of the structural dowels. The Structural Engineer should account for potential differential settlement through use of sufficient control joints, appropriate reinforcing or other means. Floor Slab Construction Considerations Finished subgrade within and for at least 10 feet beyond the floor slab should be protected from traffic, rutting, or other disturbance and maintained in a relatively moist condition until floor slabs are constructed. If the subgrade should become damaged or desiccated prior to construction of floor slabs, the affected material should be removed and structural fill should be added to replace the resulting excavation. Final conditioning of the finished subgrade should be performed immediately prior to placement of the floor slab support course. The Geotechnical Engineer should observe the condition of the floor slab subgrades immediately prior to placement of the floor slab support course, reinforcing steel and concrete. Attention should be paid to high traffic areas that were rutted and disturbed earlier, and to areas where backfilled trenches are located. LATERAL EARTH PRESSURES Design Parameters Structures with unbalanced backfill levels on opposite sides should be designed for earth pressures at least equal to values indicated in the following table. Earth pressures will be influenced by structural design of the walls, conditions of wall restraint, methods of construction and/or compaction and the strength of the materials being restrained. Two wall restraint conditions are shown. Active earth pressure is commonly used for design of free-standing cantilever retaining walls and assumes wall movement. The "at -rest" condition assumes no wall movement and is commonly used for basement walls, loading dock walls, or other walls restrained at the top. The recommended design lateral earth pressures do not include a factor of safety and do not provide for possible hydrostatic pressure on the walls (unless stated). Responsive ■ Resourceful ■ Reliable 14 Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 S = Surcharge 0 iorizontal -inished 3rade III 1 rerracon GeoReport For active pressure moveme (0.002 H to 0.004 H) For at -rest pressure - No Movement Assumed Horizontal Finished Grade �p2—*—p1Retaining Wall Lateral Earth Pressure Design Parameters Earth Pressure Coefficient for Backfill Uniform Pressure 3, 4, s Effective Fluid Condition 1 Type p, (psf) Pressures (psf) 2, 4, s, s Active Ka 0.31 0.31 S 40 H At -Rest Ko 0.47 0.47 S 60 H Passive K 3.25 --- 350 H (7)H — Active Seismic --- (12)H — At -Rest 1. For active earth pressure, wall must rotate about base, with top lateral movements 0.002 H to 0.004 H, where H is wall height. For passive earth pressure, wall must move horizontally to mobilize resistance. 2. Uniform, horizontal backfill, compacted to at least 92 percent of the ASTM D 1557 maximum dry density, rendering a unit weight of approximately 125 pcf. 3. Uniform surcharge, where S is surcharge pressure. 4. Loading from heavy compaction equipment is not included. 5. No safety factor is included in these values. 6. Values are in addition to static earth pressures Back -fill placed against structures should consist of granular soils or low plasticity cohesive soils. For the granular values to be valid, the granular backfill must extend out and up from the base of the wall at an angle of at least 45 and 60 degrees from vertical for the active and passive cases, respectively. The basement walls connected to multiple floors are best represented by an "at -rest" earth pressure condition due lateral movements of the walls being restrained by the floors. During seismic loading, a moment reduction of up to 80 percent can be applied to basement walls as a result of the stiffer, horizontal floors carrying a higher portion of the seismic load. Responsive ■ Resourceful ■ Reliable Geotechnical Engineering Report lrerracon Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 GeORepOrt EXCAVATION DESIGN Based on the soil conditions observed at the exploration locations and the assumed basement floor slab depth of roughly 14 feet below existing grade, we recommend a soldier pile and lagging shoring system to temporarily support the excavation required to construct the below grade portions of the building. Recommendations for soldier piles that are both cantilevered and supported laterally with a single row of tiebacks are provided. Provided adequate distance is available, temporary slope cuts can be combined with the shoring system to reduce the height. The shoring required to support the excavation is typically used as back forms for the permanent basement walls. Terracon should be included in discussions with the design team regarding design of temporary shoring systems for this project and should review the shoring design for compliance with the recommendations for shoring provided in this report. The following design and construction parameters are provided for preliminary planning purposes. Soldier Piles Soldier piles for shoring are typically set in drilled holes and backfilled with lean concrete. If tiebacks are used, structural concrete is placed in the bottom 5 to 10 feet. Soldier pile installation for this site may involve casing the holes and/or drilling with a mud slurry to cut-off groundwater seepage. Passive earth pressures acting on the embedded portion of the soldier piles resist horizontal loads on the shoring system. We recommend using an allowable equivalent fluid unit weight of 350 Ibs per cubic ft. for passive resistance. The passive earth pressure will act over three times the diameter of the concreted soldier pile section, or the pile spacing, whichever is less. The active earth pressures act over the concreted pile diameter below the base of the excavation. A minimum embedment of 10 feet is recommended. For a shoring system with a single row of tieback anchors, we recommend the apparent earth pressure theory for sands (i.e. Figure 24) presented in the Federal Highway Administration Geotechnical Engineering Circular No. 4: Ground Anchors and Anchors Systems (FHWA 1999). For calculating the maximum ordinate of the diagram, P, assume an active earth pressure coefficient of 0.31 and a total unit weight of 125 Ibs per cubic foot (pcf) For traffic loads adjacent to the shoring walls, add a uniform surcharge load equivalent to 250 Ibs per sq. ft; For other loads adjacent to the shoring (e.g., heavy construction loads and building foundations), contact Terracon to estimate appropriate surcharge pressures. Seismic earth pressures are typically not included in shoring design but should be considered if the excavation is to remain open for longer durations. Responsive ■ Resourceful ■ Reliable 16 Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport, Vertical capacity of the soldier piles are provided by a combination of end bearing and side friction below the base of the excavation. The piles can be designed for an allowable end bearing capacity and side friction of 20 ksf and 2 ksf, respectively. These values include a factor of safety of 2. Tieback Anchors For tieback anchors, the anchor portion of the tieback should be located sufficiently far behind the excavation shoring to stabilize the excavation face. This "no load" zone is the area behind the soldier pile equal to a lateral distance from the base of the excavation equal to the exposed wall height (H in feet) divided by four, or five feet, whichever is greater, and a line sloping up and back at 60 degrees from horizontal. The selection of the tieback materials and installation methods should be the responsibility of the contractor. The actual adhesion values will depend on the materials and installation method and should be confirmed by testing. For non -pressure grouted anchors, the allowable design concrete/soil adhesion value of 2,000 psf is recommended for the glacially consolidated soils (i.e. bond zone at least about 13 feet below existing ground). For pressure grouted anchors, this value can typically be increased by up to two times. For preliminary design purposes, we recommend an ultimate pullout capacity of 10 kips/foot for 6-inch diameter, secondary pressure grouted anchors. A factor of safety of 2 should be applied to the ultimate pullout capacity. We recommend all tieback anchors be proof tested to at least 130% of the design capacity prior to locking off at the specified post -tensioned design load. Prior to installation of production anchors, two verification tests to 200% of the design pull out capacity are recommended for each soil type in order to confirm the design anchor capacity. The anchor spacing should be at least four feet center to center in order to avoid group effects and the potential for anchors conflict with each other during installation. The anchor holes should be drilled at an angle of 15 to 45 degrees down from horizontal. A minimum anchor bond of 10 feet is recommended. The location and presence of existing features such as utilities should be checked during the design as these may affect the location and length of tieback anchors. Lagging We recommend timber lagging, or some other form of protection, be installed in all areas. Due to soil arching effects, lagging may be design based on the requirements presented in presented in the Federal Highway Administration Geotechnical Engineering Circular No. 4: Ground Anchors and Anchors Systems (FHWA 1999). Prompt and careful installation of lagging would reduce potential loss of ground. The requirements for lagging should be made the responsibility of the shoring subcontractor to prevent soil failure, sloughing, and loss of ground. Proper installation of lagging is critical to provide safe working conditions. We recommend that any voids between the lagging and soil be backfilled promptly. However, the backfill should not allow potential hydrostatic pressure to build-up behind the wall. Drainage behind the wall must be maintained. Voids behind Responsive ■ Resourceful ■ Reliable Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport, the lagging should be backfilled immediately with a permeable granular soil material or lean concrete. The excavation height prior to lagging installation should not exceed 4 feet to maintain stability of the cut face. Soldier Pile Shoring Installation The contractor should be required to prevent caving and loss of ground in all soldier pile drill holes. The shoring contractor will need to use methods to minimize caving and sloughing of the drill holes, such as the use of augercast methods or installation of casing. If more than one foot of water is present in the bottom of the hole, placement of concrete from the bottom of the hole using tremie methods will be required. When drilling tieback anchor holes, casing may be required to prevent caving and loss of ground. The anchor grout should be pumped into the anchor zone by tremie methods in order to remove water from the hole and to provide a continuous grouted anchor. Monitoring of Temporary Shoring Any time an excavation is made below the level of existing buildings, utilities, or other structures, there is risk of damage even if a well -designed shoring system has been planned. We recommend, therefore, that a systematic program of observations be conducted on adjacent facilities and structures. The monitoring program should include measurements of the horizontal and vertical movements of the adjacent structures and the shoring system itself. At least two reference lines should be established adjacent to the excavation at horizontal distances backfrom the excavation space of about 1/3H and H, where H is the final excavation height. Monitoring of the shoring system should include measurements of horizontal movements at the top of every other soldier pile. If local wet areas are noted within the excavation, additional monitoring points may be recommended by Terracon. The measuring system used for shoring monitoring should have an accuracy of at least 0.01-feet. All reference points on the existing structures should be installed and readings taken prior to commencing the excavation. All reference points should be read prior to and during critical stages of construction. The frequency of readings will depend on the results of previous readings and the rate of construction. As a minimum, readings should be taken about once a week throughout construction until the basement walls are completed. All readings should be reviewed by Terracon. STORMWATER MANAGEMENT The subsurface conditions were evaluated for infiltration potential for stormwater management. Sieve analyses were performed at 10 and 20 feet bgs for estimating an infiltration rate. In general, Responsive ■ Resourceful ■ Reliable Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 Irerracon GeoReport, the soils observed exhibit an appreciable fines content (i.e. percent passing the #200 sieve) which is the soil particle size that largely influences soil permeability. The fines content observed for the soils at these depths are about 15 and 28 percent, respectively. In addition, the soils at these depths are dense to very dense. A soil unit that would be considered favorable for stormwater infiltration was not encountered in any of the borings. Based on particle size analysis alone, an infiltration rate of up to to'/z inch per hour is estimated. However, analysis by particles size does not take soil packing density and is therefore not necessarily representative of in situ conditions. Glacially consolidated soils, such as glacial till, are generally very dense with small amounts of porewater space available. A pilot infiltration study is typical required for evaluating stormwater infiltration potential of glacially consolidated soils. It is unlikely that the results of an infiltration study would conclude that the site is suitable for stormwater infiltration. Therefore, stormwater management via infiltration is not recommended. Onsite storage with tie-in to the City of Edmonds stormwater system should be considered. GENERAL COMMENTS Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration. Natural variations will occur between exploration point locations or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. Terracon should be retained as the Geotechnical Engineer, where noted in this report, to provide observation and testing services during pertinent construction phases. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on -site, we should be immediately notified so that we can provide evaluation and supplemental recommendations. Our Scope of Services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. Our services and any correspondence or collaboration are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third -party beneficiaries intended. Any third -party access to services or correspondence is solely for information purposes to support the services provided by Terracon to our client. Reliance upon the services and any work product is limited to our client, and is not intended for third parties. Any use or reliance of the provided information by third parties is done solely at their own risk. No warranties, either express or implied, are intended or made. Responsive ■ Resourceful ■ Reliable 19 Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport Site characteristics as provided are for design purposes and not to estimate excavation cost. Any use of our report in that regard is done at the sole risk of the excavating cost estimator as there may be variations on the site that are not apparent in the data that could significantly impact excavation cost. Any parties charged with estimating excavation costs should seek their own site characterization for specific purposes to obtain the specific level of detail necessary for costing. Site safety, and cost estimating including, excavation support, and dewatering requirements/design are the responsibility of others. If changes in the nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing. Responsive ■ Resourceful ■ Reliable 20 ATTACHMENTS Responsive ■ Resourceful ■ Reliable Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 EXPLORATION AND TESTING PROCEDURES Field Exploration Number of Borings Boring Depth (feet) 1 Terracon GeoReport Planned Location B-1 21 '/2 Northeast corner of lot B-2, B-4 26'/2 Northwest, Southeast comers of lot B-3 26'/2 Approx. center of lot Boring Layout and Elevations: Terracon personnel provided the boring layout. Coordinates were obtained with a handheld GPS unit (estimated horizontal accuracy of about ±10 feet). If elevations and a more precise boring layout are desired, we recommend boring locations be surveyed. Subsurface Exploration Procedures: We advanced the borings with a track -mounted, ATV - mounted rotary drill rig using continuous flight hollow -stem augers. Samples were obtained in 5- foot intervals from each boring using a split -barrel sampling procedure. In this procedure, a standard 2-inch outer diameter split -barrel sampling spoon was driven into the ground by a 140-pound automatic hammer falling a distance of 30 inches. The number of blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration is recorded as the Standard Penetration Test (SPT) resistance value. The SPT resistance values, also referred to as N-values, are indicated on the boring logs at the test depths. In boring B-2, the boring was inadvertently advanced through a previously abandoned borehole as evident by the hydrated bentonite returned in the auger cutting. Due to time restriction in the day, Terracon elected to drill out the boring until native soils were encountered, which was approximately 18 feet. Sampling, as stated above, was performed at 20 and 25 feet. We observed and recorded groundwater levels during drilling and sampling. All borings were backfilled with granular bentonite after their completion and pavements were patched pre -mixed concrete. The sampling depths, penetration distances, and other sampling information was recorded on the field boring logs. The samples were placed in appropriate containers and taken to our soil laboratory for testing and classification by a Geotechnical Engineer. Our exploration team prepared field boring logs as part of the drilling operations. These field logs included visual classifications of the materials encountered during drilling and our interpretation of the subsurface conditions between samples. Final boring logs were prepared from the field logs. The final boring logs represent the Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 1 of 2 Geotechnical Engineering Report Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport Geotechnical Engineer's interpretation of the field logs and include modifications based on observations and tests of the samples in our laboratory. Laboratory Testing The project engineer reviewed the field data and assigned laboratory tests to understand the engineering properties of the various soil strata, as necessary, for this project. Procedural standards noted below are for reference to methodology in general. In some cases, variations to methods were applied because of local practice or professional judgment. Standards noted below include reference to other, related standards. Such references are not necessarily applicable to describe the specific test performed. ASTM D2216 Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass ASTM D6913 Standard Test Methods for Particle -Size Distribution (Gradation) of Soils Using Sieve Analysis ASTM D1140 Standard Test Method for determining the Amount of Material Finer than 75-pm (No. 200) Sieve in Soils by Washing The laboratory testing program often included examination of soil samples by an engineer. Based on the material's texture and plasticity, we described and classified the soil samples in accordance with the Unified Soil Classification System. For further soil classification, the following index tests were performed: 5 — ASTM D2216 (Water Content) 3 — ASTM D6913 (Grain Size Distribution) 2 — ASTM D1140 (No. 200 Wash) Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 2 of 2 SITE LOCATION AND EXPLORATION PLANS Contents: Site Location Plan Exploration Plan Responsive ■ Resourceful ■ Reliable SITE LOCATION Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport 14 n SO OP • C2 .. Ei- --o-� Y ,.14' :l • r l ��'7 IF�, y • •\, .\ 1 i 5- f •,s .11,iSJ'�1 ��II { ' t' •. ;�, I,_+i u�•..r •I �. - -.� It, irw n. 1 •• •�. gills •• ��'.• ` �� �i� l r-o:!w S TF e'ta _.� : f -i -�•" S _jam 714 VIZ., J , t Ir I. •�M K ••�N f. -3O. J.9�cr •: • •M '1�-. it • rl it i� � R]�T • ./ r-�• Sfr` .•'x+�.! .� t? } [j �1 � �'• % �• � •� ! q�� . � , ,�r11I-.r- r� � , J ��N1C4 `• • 1 � •ti � Cf �' �� � F�i:YMrBn� � . 1 : •► I .' j I I � ; � � • ,-'� � : f • I 1 ` '�, ;' -' •� J 1 1.I ;•. : 'ice �;.' -.. � 'l,.t�.SCk�: :• .:I:r-':�, i+l � `1-= ''I 1 j= -.;1� - ArT i • � ; �' � • •. �.�+` •� •I . �;� ..i • J • ;,I ,`�I' 15��,` 1 I•l�• I �'} `.1 • • lam Ll rr I . • I r-I '. V 'r - "�--r- f (� I • �• ;, , , ♦ Historical Terracon Project , ly )IAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS EXPLORATION PLAN Edmonds Senior Living Edmonds, Washington December 20, 2018 Terracon Project No. 81185173 1 rerracon GeoReport EXPLORATION RESULTS Contents: Boring Logs (B-1 through B-4) Grain Size Distribution BORING LOG NO. B-1 Pane 1 of 1 I IL of 0 z w U) U) 0 0 2 0 w LU m eo >J 0 z 6 0 J H Q 0 W U PROJECT: Edmonds Senior Living CLIENT: CA Senior Living Holdings, LLC Chicago, IL SITE: 21200 72nd Ave. W Edmonds, WA 0 LOCATION See Exploration Plan J Z w w w O Latitude: 47.8067° Longitude:-122.3303° LL w ¢~ a F F m o w z z F D J W o J w z (If 0 Approximate Surface Elev.: 380 (Ft.) +/- o ¢ M a W EL 2 Ov w ION DEPTH ELEVATFt. O U) a 0.6 ASPHALT, approx. 1.5 inches of asphalt over 2 inches base coarse 379.5+/- SANDY SILT (ML), trace gravel, fine to coarse grained, olive brown to dark brown, moist to wet, soft, trace organics (FILL) 5 12 6-1-5 S-1 N=6 7.5 372.5+/- SILTY SAND (SM), reddish brown to brown, moist, medium dense, (RECESSIONAL OUTWASH) rust staining in top of S-2, possibly evidence of seasonal groundwater 1 18 8-15-16 N=31 S 2 10.5 369.5+/- SANDY SILT (ML), olive gray to gray, moist, very stiff, (GLACIAL TILL) 13.0 367+/- SILTY SAND (SM), trace gravel, gray, moist, very dense 1 16-16 24 trace gravel, dense, interbedded silt 18 N=40 S-3 2 18 11-30-50/6" N=80/12" S-4 14 28 rock fragment in S-4, possibly over -stated blow -count 21.5 358.5+/- Boring Terminated at 21.5 Feet Stratification lines are approximate. In -situ, the transition may be gradual. Hammer Type: Automatic (ETR = 88%) Advancement Method: See Exploration and Testing Procedures for a Notes: Hollow Stem Auger description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. Abandonment Method: Boring backfilled with Auger Cuttings and/or Bentonite Surface Capped with Asphalt Elevations were estimated from Google Earth WATER LEVEL OBSERVATIONS Irerracon Boring Started: 12-05-2018 Boring Completed: 12-05-2018 Drill Rig: D-50track Driller: Holocene 21905 64th Ave W, Ste 100 Mountlake Terrace, WA Project No.: 81185173 BORING LOG NO. B-2 Pane 1 of 1 I EL t7 J C 0 z W z Z 0 0 w J 0 z 6 0 a U) 0 0 PROJECT: Edmonds Senior Living CLIENT: CA Senior Living Holdings, LLC Chicago, IL SITE: 21200 72nd Ave. W Edmonds, WA 0 LOCATION See Exploration Plan z w w ^ rn Lu O Latitude: 47.8067° Longitude:-122.331 ° w �¢ a ~ � F Com D o w z F o Jw w z (If0 Approximate Surface Elev.: 382 (Ft.) +/_ m ¢ m Q W oOf J 2 O w O W a DEPTH ELEVATION Ft. 0.6 ASPHALT, approx. 1.5 inches of asphalt over 2 inches of base coarse 381.5+/- DRILL OUT 5 1 1 20.0 362+/ 2 POORLY GRADED SAND WITH SILT (SP-SM�, light brown to brown, 4-13 25 moist, dense, (GLACIAL TILL) 12 N=38 S-4 22.5 359.5+/- SILTY SAND (SM), reddish brown to olive gray, moist, very dense, silty sand with interbedded silt 2 25-30-36 rust staining in S-5, possibly evidence of seasonal groudwater 18 N=66 S 5 ..26.5 355.5+/- Boring Terminated at 26.5 Feet Stratification lines are approximate. In -situ, the transition may be gradual. Hammer Type: Automatic (ETR = 88%) Advancement Method: See Exploration and Testing Procedures for a Notes: Hollow Stem Auger description of field and laboratory procedures Boring passed through an abandoned borehole of unknown used and additional data (If any). nature. Drill out upper 20 feet due to evidence of borehole See Supporting Information for explanation of symbols and abbreviations. backfill. Abandonment Method: Boring backfilled with Auger Cuttings and/or Bentonite Surface Capped with Asphalt Elevations were estimated from Google Earth WATER LEVEL OBSERVATIONS Irerracon Boring Started: 12-05-2018 Boring Completed: 12-05-2018 Drill Rig: D-50track Driller: Holocene 21905 64th Ave W, Ste 100 Mountlake Terrace, WA Project No.: 81185173 BORING LOG NO. B-3 Pane 1 of 1 'a q J of _0 z III 0 0 2 0 w LU n m eo >J 0 z 6 0 J Q U) 0 Lu PROJECT: Edmonds Senior Living CLIENT: CA Senior Living Holdings, LLC Chicago, IL SITE: 21200 72nd Ave. W Edmonds, WA 0 LOCATION See Exploration Plan J Z w w w O Latitude: 47.8066° Longitude:-122.3307° v w Q~ a Lu Coo w Z z F o w z 0 Approximate Surface Elev.: 378 (Ft.) +/- c ¢ M a W Of 2 Ov w DEPTH ELEVATION Ft. O U) a TOPSOIL + SAND WITH SILT (SP-SM), trace gravel, brown to grayish brown, moist, medium dense, some woody debris and cobbles (FILL) 3.5 374.5+/- SAND WITH SILT (SP-SM), light brown to brown, moist, medium dense, (RECESSIONAL GLACIAL OUTWASH) 5 6 5-6-13 S-1 N=19 increasing silt content, transitions to silty sand 10.0 368+/- 1 SILTY SAND (SM), light brown to brown, moist, dense, (GLACIAL 15-18-13 TILL) 16 N=31 S-2 1 15 10-15-15 S-3 16 13 N=30 rust staining in S-4, possibly evidence of seasonal groundwater 2 18 10-11-21 N_32 S-4 20.5 357.5+/- z1.o SANDY SILT (MLA, reddish brown to olive brown, moist, hard 357+/- SAND (SP), trace silt, brown to reddish brown, moist, dense rust staining in S-5, possibly evidence of seasonal groundwater 2 18 25-33-37 N-70 S-5 .''.•' 25.5 352.5+/- SILTY SAND (SM), gray to dark gray, moist, very dense 26.5 351.5+/- Boring Terminated at 26.5 Feet Stratification lines are approximate. In -situ, the transition may be gradual. Hammer Type: Automatic (ETR = 88%) Advancement Method: See Exploration and Testing Procedures for a Notes: Hollow Stem Auger description of field and laboratory procedures Boring located in landscaped area. u used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. Abandonment Method: Boring backfilled with Auger Cuttings and/or Bentonite Surface Capped with Asphalt Elevations were estimated from Google Earth WATER LEVEL OBSERVATIONS Irerracon Boring Started: 12-05-2018 Boring Completed: 12-05-2018 Drill Rig: D-50 track Driller: Holocene 21905 64th Ave W, Ste 100 Mountlake Terrace, WA Project No.: 81185173 BORING LOG NO. B-4 Pane 1 of 1 'a of 0 z w U) U) 0 0 2 0 w n J J w 0 z 6 0 J Q U) 0 Lu PROJECT: Edmonds Senior Living CLIENT: CA Senior Living Holdings, LLC Chicago, IL SITE: 21200 72nd Ave. W Edmonds, WA 0 LOCATION See Exploration Plan J Z w w w O Latitude: 47.8064° Longitude:-122.3304° v U,a Q~ Lu coo w Z z F o w z 0 Approximate Surface Elev.: 377 (Ft.) +/- c ¢ M a W Of 2 Ov w DEPTH ELEVATION Ft. O rn a ASPHALT, approx. 1.5 inches asphalt over 2 inches base coarse + SILTY SAND WITH GRAVEL (SMI, dark brown with olive brown o mottling, moist, loose, woody debris (FILL) q 12 S-1 5.5 371.5+/- 5 14 2-2-2 N_4 S-2 SILTY SAND (SM), grayish brown to brown, moist, medium dense, sand with silt interbeds (RECESSIONAL GLACIAL OUTWASH) 1 15 7-7-7 S-3 19 15 N=14 13.0 364+/- SAND WITH SILT (SP-SM), light brown to brown, moist, dense to very dense, silt interbeds (GLACIAL TILL) 1 16-27-28 decreasing silt content 17 N=55 S 4 9 6 18.0 359+/- SANDY SILT (ML), light brown, moist, hard rust staining observed in top of S-4, possible evidence of seasonal 20.5 groundwater 356.5+/- 2 18 9N=46 46 S-5 SAND WITH SILT (SP-SMI, trace silt, brown, wet, dense becomes dark gray, very dense 2 17 18-30-36 N=66 S 6 25 89 25.5 351.5+/- SILT ML , trace sand, gray, moist, hard 26.5 350.5+/- Boring Terminated at 26.5 Feet Stratification lines are approximate. In -situ, the transition may be gradual. Hammer Type: Automatic (ETR = 88%) Advancement Method: See Exploration and Testing Procedures for a Notes: Hollow Stem Auger description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. Abandonment Method: Boring backfilled with Auger Cuttings and/or Bentonite Surface Capped with Asphalt Elevations were estimated from Google Earth WATER LEVEL OBSERVATIONS Irerracon Boring Started: 12-05-2018 Boring Completed: 12-05-2018 While sampling Drill Rig: D-50 track Driller: Holocene 21905 64th Ave W, Ste 100 Mountlake Terrace, WA Project No.: 81185173 GRAIN SIZE DISTRIBUTION ASTM D422 / ASTM C136 r 100 95 90 85 80 75 70 65 w 60 >- 55 m ry w 50 z LL 1-- 45 z w 40 w a 35 30 25 20 15 10 5 0 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS I HYDROMETER n o 1 a 11) 19 an �n inn ono ME1IIIYIII�■�.ii.�lllwlll■■■IIIIII■■■ IMM UNE Ul�, 100 10 1 0.1 GRAIN SIZE IN MILLIMETERS 0.01 0.001 COBBLES VV��LCJ GRAVEL SAND SILT OR CLAY ���� OR Vu+►i coarse fine coarse medium fine Boring ID Depth USCS Classification WC (°io) LL Pq JILPI Cc Cu • B-1 20 - 21.5 silty SAND (SM) m B-4 10 - 11.5 silty SAND (SM) A B-4 25 - 26.5 SILT (ML) Boring ID MaDepth D1oo J D60 D10 %Gravel %Sand %Silt %Fines %Clay 40 B-1 20 - 21.5 19 0.267 0.084 11.8 60.7 27.5 m B-4 10 - 11.5 19 0.249 0.133 2.1 83.4 14.5 A B-4 25 - 26.5 2 0.0 11.2 88.8 PROJECT: Edmonds Senior Living PROJECT NUMBER: 81185173 Irerracon SITE: 21200 72nd Ave. W 21905 64th Ave W, Ste 100 CLIENT: CA Senior Living Holdings, LLC Edmonds, WA Mountlake Terrace, WA Chicago, IL SUPPORTING INFORMATION Contents: General Notes Unified Soil Classification System GENERAL NOTES DESCRIPTION OF SYMBOLS AND ABBREVIATIONS Edmonds Senior Living — Edmonds, WA December 20, 2018 ■ Terracon Project No. 81185173 SAMPLING . WATER LEVEL Water Initially Encountered Standard Grab Penetration Water Level After a Specified Period of Time Sample Test Water Level After a Specified Period of Time Water levels indicated on the soil boring logs are the levels measured in the borehole at the times indicated. Groundwater level variations will occur over time. In low permeability soils, accurate determination of groundwater levels is not possible with short term water level observations. lrerracon GeoReport FIELD TESTS N Standard Penetration Test Resistance (Blows/Ft.) (HP) Hand Penetrometer (T) Torvane (DCP) Dynamic Cone Penetrometer UC Unconfined Compressive Strength (PID) Photo -Ionization Detector (OVA) Organic Vapor Analyzer DESCRIPTIVE SOIL CLASSIFICATION Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non -plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse -grained soils are defined on the basis of their in -place relative density and fine-grained soils on the basis of their consistency. LOCATION AND ELEVATION NOTES Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy of such devices is variable. Surface elevation data annotated with +/-indicates that no actual topographical survey was conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic maps of the area. STRENGTH TERMS RELATIVE DENSITY OF COARSE -GRAINED SOILS CONSISTENCY OF FINE-GRAINED SOILS (More than 50% retained on No. 200 sieve.) (50% or more passing the No. 200 sieve.) Density determined by Standard Penetration Resistance Consistency determined by laboratory shear strength testing, field visual -manual procedures or standard penetration resistance Descriptive Term Standard Penetration or Descriptive Term Unconfined Compressive Strength Standard Penetration or (Density) N-Value (Consistency) Qu, (tsf) N-Value Blows/Ft. Blows/Ft. Very Loose 0-3 Very Soft less than 0.25 0-1 Loose 4-9 Soft 0.25 to 0.50 2-4 Medium Dense 10 - 29 Medium Stiff 0.50 to 1.00 4-8 Dense 30 - 50 Stiff 1.00 to 2.00 8 - 15 Very Dense > 50 Very Stiff 2.00 to 4.00 15 - 30 Hard > 4.00 > 30 RELATIVE PROPORTIONS OF SAND AND GRAVEL RELATIVE PROPORTIONS OF FINES Descriptive Term(s) of other constituents Percent of Dry Weight Descriptive Term(s) of other constituents Percent of Dry Weight Trace <15 Trace <5 With 15-29 With 5-12 Modifier >30 Modifier >12 GRAIN SIZE TERMINOLOGY PLASTICITY D'ESCRIPTIONlllIIIIIIIIIIIIIIII Major Component of Sample Particle Size Term Plasticity Index Boulders Over 12 in. (300 mm) Non -plastic 0 Cobbles 12 in. to 3 in. (300mm to 75mm) Low 1 - 10 Gravel 3 in. to #4 sieve (75mm to 4.75 mm) Medium 11 - 30 Sand #4 to #200 sieve (4.75mm to 0.075mm High > 30 Silt or Clay Passing #200 sieve (0.075mm) UNIFIED SOIL CLASSIFICATION SYSTEM 1 rerracon Geo—Re port Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Coarse -Grained Soils: More than 50% retained on No. 200 sieve Fine -Grained Soils: 50% or more passes the No. 200 sieve Clean Gravels: Gravels: Less than 5% fines c More than 50% of coarse fraction retained on No. 4 sieve Gravels with Fines: More than 12% fines c Sands: 50% or more of coarse fraction passes No. 4 sieve Clean Sands: Less than 5% fines o Cu>_4and 1<_Cc<3E Cu < 4 and/or [Cc<1 or Cc>3.0] E Fines classify as ML or MH Fines classify as CL or CH Cu>_6and 1<_Cc<3E Cu < 6 and/or [Cc<1 or Cc>3.0] E Fines classify as ML or MH Soil Classification Group >ymbol Group Name B GW Well -graded gravel F GP Poorly graded gravel F GM Silty gravel F, G, H GC Clayey gravel F, G, H SW Well -graded sand SP Poorly graded sand SM Silt sand G, H, i Sands with Fines: y More than 12% fines o Fines classify as CL or CH SC Clayey sand G, H, i Inorganic: PI > 7 and plots on or above "A" CL Lean clay K, L, M Silts and Clays: Liquid limit less than 50 I PI < 4 or plots below "A" lines ML Silt K, L, M Organic: Liquid limit - oven dried < 0.75 OL Organic clay K, L, M, N Liquid limit -not dried Organic silt K, L, M, o Silts and Clays: Liquid limit 50 or more Inorganic: PI plots on or above "A" line CH Fat clay K, L, M PI plots below "A" line MH I Elastic Silt K, L, M Organic: Liquid limit - oven dried < 0.75 OH Organic clay K, L, M, P Liquid limit -not dried Organic silt K, L, M, Q Highly organic soils: I Primarily organic matter, dark in color, and organic odor PT Peat A Based on the material passing the 3-inch (75-mm) sieve. H If fines are organic, add "with organic fines" to group name. B If field sample contained cobbles or boulders, or both, add "with cobbles I If soil contains >_ 15% gravel, add "with gravel" to group name. or boulders, or both" to group name. J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. c Gravels with 5 to 12% fines require dual symbols: GW-GM well -graded Kif soil contains 15 to 29% plus No. 200, add "with sand" or "with gravel with silt, GW-GC well -graded gravel with clay, GP -GM poorly gravel," whichever is predominant. graded gravel with silt, GP -GC poorly graded gravel with clay. If soil contains >_ plus No. 200 predominantly sand, add o Sands with 5 to 12% fines require dual symbols: SW-SM well -graded name. "sandy" to group name. sand with silt, SW -SC well -graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay. MIf soil contains >_ 30% plus No. 200, predominantly gravel, add 2 "gravelly" to group name. (D 30) H PI >_ 4 and plots on or above "A" line. E Cu = D6o/D,o Cc = o PI < 4 or plots below "A" line. D10 x D60 "A" P PI plots on or above line. F If soil contains >_ 15% sand, add "with sand" to group name. QPl plots below "A" line. G If fines classify as CL-ML, use dual symbol GC -GM, or SC-SM.