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Home My WebLink AboutGEO2020-00077 for BLD2020-01295 - GEO Geological Review - 8/18/2020 G EOTEcHNicAL REPORT RESIDENTIAL DEVELOPMENT SITE 71 NE SCHOONER PLACE BELFAIR, WASHINGTON PREPARED FOR RJ PEABODY, INC. BY ALL AMERICAN GEOTECHNICAL OLYMPIA, WASHINGTON AUGUST 18, 2020 ALL AMMC AN GEOTWANICAL CON TACT INFOR MATION PREPARER INFORMATION AAG PROJECT NUMBER: AAG20-067 CONTACT: CURTIS D.CUSHMAN ADDRESS: 8947 BUTTONWOOD LANE NE OLYMPIA,WASHINGTON 98516 TELEPHONE: (360)491-5155 CELL/TEST: (360)481-6677 EMAIL ADDRESS: CURTIS.CUSHMAN@COMCAST.NET CLIENT INFORMATION CLIENT: RJ PEABODY,INC. TELEPHONE: (360)895-3235 BILLING ADDRESS: RJ PEABODY,INC. P.O.Box 565 BURLEY,WA 98322 SITE ADDRESS: 71 NE SCHOONER LANE BELFAIR,WASHINGTON EMAII, RJREALESTATE@MSN.COM PARCEL NUMBER 12330-52-00019 GPS LOCATION: 47.454 -122.848 AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 2 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AEIC AN GEOTECHNICAL SCOPE OF UNDERSTANDING RJ PEABODY,INC. P.O.Box 565 BURLEY,WASHINGTON 98322 RE: GEOTECHNICAL REPORT PROPOSED RESIDENCE 71 NE SCHOONER LANE BELFAIR,WASHINGTON 47.454 -W 122.848 PARCEL: 12330-52-00019 AUGUST 18,2020 Dear Sirs: RJ Peabody(client)hired All American Geotechnical,Inc. (AAG)in June 2020 to conduct a geotechnical investigation and prepare a geotechnical report for a residential property on a lot in Mason County, Washington. The following is the report written to comply with the Mason County Requirements in the Critical Areas Ordinance in accordance with the Submittal Checklist For a Geotechnical Report for the above property near the city of Belfair in Mason County,Washington. The site is to be developed for residential and other rural uses associated with a single family residence. As per client request, we did a relevant site visit and a search of public documents. A copy will be provided to the client by PDF. Landslide hazards will be noted and analyzed in text. Other geotechnical information is likewise included. We appreciate this opportunity to be of service to you and we look forward to working with you in the future. If you have any questions concerning the above items,the procedures used, or if we can be of any further assistance please call us at the phone number listed below. of Was h Respectfully Submitted, ALL AMERICAN GEOTECHNICAL,INC. Engineering ist 2439 �� Curtis D.Cushman,L.G.,L.E.G. ed Ge°110 Senior Engineering Geologist Curtis Dean Cushman AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 3 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL A :1\ OKNICAL TABLE OF CONTENTS SCOPE OF UNDERSTANDING 3 INTRODUCTION 5 1) SITE CONDITIONS 5 SURFACE CONDITIONS 5 A) SITE GEOLOGY 6 B) SOIL TYPES 7 C) GROUND WATER CONDITIONS 8 D) UPSLOPE GEOMORPHOLOGY 8 E) UPSLOPE WATERBODIES AND WETLANDS 8 F) LANDSLIDE ACTIVITY 8 2) SITE PLAN 8 3) EXPLORATORY HOLES OR PROBES 8 4) PROPOSED DEVELOPMENT 8 5) CROSS SECTION 8 6) SLOPE STABILTY ANALYSIS 9 SEISMIC LIQUEFACTION HAZARD 10 GEOSEISMIC SETTING 10 LATERAL EARTH PRESSURES 10 CONCLUSIONS AND RECOMMENDATIONS 14 PROVISIONS 14 READ THESE PROVISIONS CLOSELY 15 APPENDIX 15 REFERENCES 16 2015 AASHTO DESIGN SPECIFICATIONS 18 SLOPE MODELS 20 STATIC MODEL A-A' 20 DYNAMIC MODEL A-A' 21 FIGURES 22 FIGURE 1 VICINITY MAP 22 FIGURE 2. SITE PLAN 23 FIGURE 3. EROSION CONTROL NOTES 24 AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 4 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL ACA OCHNICA INTRODUCTION This report summarizes the results of our geotechnical study of the parcel herein described. The parcel is a truncated triangle long to the east-west with the base to the east and the western tip truncated by an arc corresponding to the cul-de-sac of NE Schooner Lane. The parcel is currently undeveloped. In general,the property descends to the east. There is a short drop-off at the road leading to a platform on the south side of the property. The property then descends to a stream off-parcel. The lowest part of the parcel flattens at the base of the slope where the residence is proposed to be located. The property is covered with fairly heavy second-growth trees and common underbrush. The elevation ranges from 205 feet at its southeast tip to 235 feet at NE Schooner Lane on the east. Our understanding of the project is based on materials sent by the client. The client plans to develop the property with a residence. Access to the parcel is directly off NE Schooner Lane in Belfair, Washington. NE Schooner Lane is accessed from State Route 300 in Belfair via NE Sand Hill Road to NE Larsen Boulevard to Schooner. This geotechnical report and the checklist for Mason County involves the following: 1. A review of the available geologic, hydrogeological and geotechnical data for the site area. 2. A detailed geologic reconnaissance of the site area and surrounding vicinity. 3. Investigation and identification of shallow subsurface conditions at the site by characterizing the exposed soil, sampling,and reviewing published well logs. 4. Comparison of the site to published geologic maps, previous field investigations, and open file reports. Inspection of aerial photographs to determine the geomorphology of the site. 5. Evaluation of the landslide, erosion, and seismic hazards at the site per the Mason County Critical Areas Ordinance regulations (as of January 1, 2007). 6. Slope modelling. As the slope is greater than 15%and is associated with apparent seepages and wetland at its foot. This is considered a geologically hazardous area. Therefore, Mason County requires that a geotechnical report be prepared in accordance with the Mason County Code Title 8 — Environmental Policy specifically 8.52.140—Geologically Hazardous Areas. No slopes of 40%were seen on site. 1) SITE CONDITIONS SURFACE CONDITIONS The proposed location for the residential development is at a flat area at the base of the slope extending east from NE Schooner Lane and into a natural drainage. The client properly overall slopes descends from west to east. AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 5 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AM-- OTECH ICAL In general,the property is basically covered with second-growth maturing conifers and scattered maples, with other juvenile deciduous. There is local undergrowth with ferns common. Curtis D Cushman, L.E.G. and Blaise Jelinek E.I.T. of AAG conducted a site reconnaissance on July 14, 2020. The purpose of a site visit is to physically observe the property and adjacent properties in order to identify any recognized geologic conditions. Visual observations were documented. On August 13, 2020 Mr, Jelinek conducted a second site visit to verify the previous observations. Surface water was observed at the flagged wetland boundary,no springs or moist paths of flow were found up slope of the wetlands. The parcel is currently undeveloped. The mature trees are generally straight and vertical showing little or no signs of slope movement. A) SITE GEOLOGY The entire parcel is mapped as Qgic-Vashon Stade glacial ice-contact deposits on the Washington Geologic Information Portal which is taken from the Belfair 7.5-minute Quadrangle, Mason County, Washington;by Polenz,Michael,et al.; 2009;DNR Open File Report 2009-07. Geologic Unit Label:Qgic Publisher:WGS Publication Number:OFR 2009-7 Quadrangle Name:Belfair Symbology:Pleistocene continental glacial drift Geologic Unit Age: Pleistocene Geologic Unit Name: Vashon Stade glacial ice-contact deposits Unit Description: Sand, gravel, lodgment till, and flow till, minor silt and clay beds; tan to gray; variably sorted; loose to compact; massive to well stratified; locally includes over-steepened beds that typically reflect sub-ice flow, but their dip may, along with small-scale shears, also have developed as collapse features or due to glaciotectonic and tectonic deformation; formed in the presence of meltwater alongside ice, generally toward the end of the glaciation, and is thus commonly accompanied by stagnant-ice features, such as kettles and less-orderly hummocky topography, eskers (also separately mapped as subunit Qge), and subglacial or subaerial outwash channels. The deposits seen on site are likely SP Gravelly sand using the ASTM classification. The nearest water well shows variable lithology but is too far away from the client property to be of use to evaluate its geologic column_ The nearest identified displacement feature is the Sunset Beach scarp—Tacoma fault on the south side of Lynch Cove, which extends several miles southwest-northeast and is approximately 4 miles to the southeast of the parcel at its closest point. This is apparently a feature of the Tacoma Fault system which is prominent in the Allyn, Washington area. Seismic acceleration is important in modelling the slope stability as the Puget Sound area is in an active tectonic zone and although this fault does not pose an immediate hazard to the proposed building project, low levels of seismic activity are not uncommon and AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 6 Phone#:(360)491-5155 Cell#:(360)481-6677 ALL. AMENCAN GBOTIECUMC there is always the possibility of a major shock. The scarp/fault trench will commonly poses no hazard to the client property. B) Sou,TYPES The soil in the areas of the proposed northwestern development is described by the USDA Web Soil Survey as: Ee—Everett gravelly loamy sand, 5 to 15 percent slopes Map Unit Setting • National map unit symbol: 2hk7 • Elevation: 50 to 500 feet • Mean annual precipitation: 55 to 90 inches • Mean annual air temperature: 48 to 50 degrees F • Frost-free period: 160 to 180 days Map Unit Composition • Everett and similar soils: 100 percent Description of Everett Setting • Landform: Terraces • Parent material: Glacial outwash Typical profile • H1 - 0 to 7 inches: gravelly ashy loamy sand • H2 - 7 to 21 inches: extremely gravelly sand • H3 - 21 to 60 inches: very gravelly sand Properties and qualities • Slope: 5 to 15 percent • Depth to restrictive feature: More than 80 inches • Drainage class: Somewhat excessively drained • Capacity of the most limiting layer to transmit water(Ksat): High to very high (5.95 to 19.98 i n/h r) • Depth to water table; More than 80 inches • Frequency of flooding: None • Frequency of ponding: None • Available water capacity: Very low (about 2.5 inches) This appears to be the soil that is seen in the surface exposures and on the slope to the east. The amount of gravel varies. The surface horizon of the soil is not important to the placement of the residence as it is relatively thin and likely to be removed in developing the footings. AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 7 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMM-SCAN GEOTIECHNICAL C) GROUND WATER CONDITIONS The ravine to the east was dry at the time of the visit. There was no ponding, springs, seeps or other water seen. There was no evidence of active surface erosion. The nearest identified water well was somewhere on Mast Road to the west,2000 feet and more away,with a depth to static water of-210 feet. D) UPSLOPE GEOMORPHOLOGY The slope ascends rather gently to a height of 350 feet on a low ridge approximately 1000 feet to the northwest. This does not constitute a geotechnical hazard to the parcel. E) UPSLOPE WATERBODIES AND WETLANDS Larson Lake is approximately 1500 feet to the northwest,just past the ridge noted above. It is at an elevation of 275 is topographically higher. As an enclosed kettle,there is little or no hazard of overflowing, and it is unlikely a catastrophic draining would affect the client property. ) LANDSLIDE ACTIVITY The 7.5-minute quadrangle shows humerus landslide in the area, but the closest are smaller ones, all associated with Mission Creek over 4000 feet to the west. There are no mapped landslides in the area of the client property, and few mapped are in Qgie deposits. LiDAR from the Mason County GIS shows no evidence of any landslides in the area around the site. There was no evidence of current on-site landslide activity. 2) SITE PLAN Please see Figure 2 in the appendix. 3) EXPLORATORY HOLES OR PROBES The column was surface examined on its slope,in the lower flat areas,and in the numerous septic test pits as located on Figure 2. 4) PROPOSED DEVELOPMENT This will be a single family residence. 5) CROSS SECTION Two cross-sections are in the appendix are in the Appendix. They are along line A-A`. AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 8 Phone#: (360)491-5155 Cell#:(360)481-6677 6) SLOPE STABILTY ANALYSIS The Slope Stability Analysis is as follows following the Mason County Resource Ordinance of 2009: 17 01,100E5(6) --A description and results of slope stability analyses performed for both static and seismic loading conditions Analysis should examine worst-case failures The analysis should include the Simplified Bishop s Method of Circles The minimum static safety factor is 1,5, the minimum seismic [dynamic] safety factor is 1.1 and the quasi-static analysis coefficients should be a value of 0.15. Slope stability was modeled using the GALENA 6.1 program in both static and dynamic conditions (ca= 0.304). "Static" condition refers to an "as is" state of a given slope. "Dynamic" puts seismic acceleration into the model for earthquake conditions. The factor for ground acceleration (ca) was determined from the Peak Ground Acceleration from the USGS Seismic Design Maps, included in the Appendix. The surface soil was field classified in the range of a SP,a Gravelly sand. These units are consistent with the description of the Qgic Vashon Stade glacial ice-contact deposits. The site was modeled as monolithic unit. Groundwater was included in the model. Parameters used for the subsurface material are presented in the table below. Table 1.Modeling Parameters for Subsurface Material Geologic Unit 11 Cohesion I Phi Angle I i Qgic-Vashon Stade Ice Contact Deposits 120 1 400 1 35 (Pleistocene) I Factors of safety were determined using the Bishop (semi-circular) method. A ground water table was not included in the model, as none was encountered. Under static conditions, the slopes did not show susceptibility to deep-seated failure that would cause damage to the existing development. See Appendix for model output and cross-sections. Under dynamic loading (Ca=0.304),the computations demonstrated that the development is safe and not susceptible to a deep-seated movement. The following are the Factors of Safety (FoS) attained for the sections with respect to their current topographical representation. General information for the slope profiles and the initial positions for analysis is presented in the following table. AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 9 Phone#:(360)491-5155 Cell#: (360)481-6677 ,p,LL, A-mudcAN GEoTWHNIC AL Table 2.Initial Positions,Variance,and Findings Analysis Loading Across Analysis Initial Positions(Analysis Range) Configurations IFactor of Number Building Area Tye M=over JUpper Radius JAnalyzed Safety . .........Cross-Section,k-A' ...125,001.... 5.'36 'Static :130(20) Ir7i -1-53'18'5 -*--...—:169 —6 .......4..................................... ...............................;....•.......... Atialysis 2 : 1500# 153-185 'Dynamic:169(34 :226(40) :130(20) 125,00 2.79 .... I.I.-................ ........... ...............I........ ............. ....... These calculated Factors of Safety (FoS) meet or exceed code standards. Thus, based on our slope models representing critical slopes at the subject site, it is apparent that the modelled sites are not susceptible to damage by deep-seated movements or instability The values input were selected to be as conservative as possible so the FoS may be higher. The graphic output of these data is presented in the appendix,pages 20-2 1. SEismic LIQUEFACTION HAZARD The Liquefaction Susceptibility Map of Mason County, Washington by Palmer, Magsino, Poelstra, Bilderback, Folger, and Niggemann(September 2004) maps the site area as having a Very Low to Low liquefaction potential. The Site Class Map of Mason County, Washington by Palmer,Magsino, Bilderback,Poelstra,Folger, and Niggemarm(September 2004) maps the area as site Class C to D. Site class C is a very stiff soil or soft rock and class D is stiff soil. GF,osEismic SETTING According to the Seismic Zone Map of the United States (Figure 1613.3.1(1)) contained in the 2015 International Building Code (IBC), the project site is located where the maximum spectral response acceleration is greater than 60 percent of gravity(g). We recommend following seismic factors for design purposes. D (stiff soil/soft rock) • Site Class: • Spectral response acceleration, short period(Sms): 1.468g(Fa= 1.05) • Spectral response acceleration, 1-second period(Smi): 0.88g (F,= 1.55) • Peak Ground Acceleration 0.608 LATERAL EARTH PRESSURES Lateral loads may be resisted by friction on the bases of footings and floor slabs and as passive pressure on the sides of footings. An allowable coefficient of friction of 0.40 may be used to calculate friction between the concrete and the underlying native soil. We recommend the following be used to determine the lateral earth pressures considering the onsite SP: AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 10 Phone#:(360)491-5155 Cell#:(360)481-6677 �,AMERICAN GEOTECUNICAL • 0 (soil friction angle) 35 degrees • Ko(at rest earth pressure coefficient) 1.428 • Ka(active earth pressure coefficient) 0.271 • Kp (passive earth pressure coefficient) 3.69 • 7 (soil unit weight) 120 pcf 7) RESTRICTIONS A) PLACEMENT OF DRAINAGE FEATURES All ground surfaces, pavements and sidewalks should be sloped away from the residence and associated structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and/or catch basins and tight lined into the appropriate drainage facilities. We recommend that conventional roof drains be installed. Footing drains shall be installed for the proposed structure. The roof drain should not be connected to the footing drain. For footing drains, the drain invert should be below the bottom of the footing. Typical drainage control measures are included on Figure 3 in the appendix. The soil will accept downspout and other drainage located at least 5 feet from the edge of the footing of the residence. Figure 3 shows recommendations for a tightline system which is a possible alternative to downspouts. B) PLACEMENT OF SEPTIC DRAIN FIELDS The drain field is located as mapped on Figure 2. Domestic water is from a community source and is thus not on Figure 2. C) PLACEMENT OF COMPACTED FILLS AND FOOTINGS RECOMMENDATIONS FOR SITE PREPARATION The area is forested and the trees shall be cleared as needed for construction. All areas to be excavated should then be cleared of deleterious matter including any debris, duff, and vegetation. All deleterious material will be removed and sub-soils reached for the footings for the construction of slab and/or footings. Any material that is excavated may be stockpiled and later used for erosion control and/or landscaping. Surficial material unsuitable for these tasks should be removed from the project site. No foundation elements shall be constructed on"untested"fill material. If demonstrated to be acceptable,the sand/gravel sedimentary material on site may be suitable for re-use as structural fill. Where placement of fill material is required, the exposed subgrade areas should be compacted to a firm and unyielding surface prior to placement of any fill. Over-excavation in any building area should be AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 11 Phone#:(360)491-5155 Cell#:(360)481-6677 ALL, AMEW,AN GROTMIL backfilled with structural fill, compacted to the density requirements described in the Structural Fill section of this report. RECOMMENDATIONS FOR STRUCTURAL FILL All fill material should be placed as structural fill. In general, the structural fill should be placed in horizontal lifts of 8 inches to allow adequate and uniform compaction of each lift. Fill should be compacted to at least 95 percent of MDD (maximum dry density as determined in accordance with ASTM D-1557)to grade. The final appropriate lift thickness will depend on the fill characteristics and compaction equipment used. Material placed for structural fill should be free of debris, organic matter, trash, and cobbles greater than 6 inches in diameter. The moisture content of the fill material should be adjusted as necessary for proper compaction. Onsite soils may be considered for use as structural fill only if industry standards are satisfied. Fill material requirements are found on page 9-26 to 9-30 of the WSDOT Standard Specifications 2010. In general, a native soil (sand, silt, and gravel) encountered on a site must have less than 10 percent fines (material passing the US No.200 sieve)to be suitable for use as structural fill. Footing design will be by the Engineer of Record. FOOTINGS The slopes were modelled using a pressure of 1500 lbs/ft2. The ground should accept this weight. However, the depth to the water table is such that there is a possibility that deep footing may encounter water. This possibility must be considered for footing design. It is recommended that upslope of the away from the residence. t r drain be considered with captured y i residence an interceptor tared water diverted o p D) BuFia ERS There is no buffer associated with a Landslide Hazard Area on site. This is derived from analysis of the slopes on maps and in the field. The construction area is acceptable as seen in the Factors of Safety in the Slope Stability Analysis section, above. The slopes are such that erosion should not be a limiting factor. E) SETBACKS The site is acceptable as seen in the high Factors of Safety. AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 12 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMENCAN GEOTECUMCALL 8) CLEARING AND GRADING PLAN Timber clearing will be needed. No grading is anticipated except to develop the foundations of the residence. "No Disturb" zones will not be required. No formal plan should be needed as long as safe procedures are employed with the clearing in keeping with Mason County regulations. All job site safety issues and precautions are the responsibility of the contractor providing services and/or work. 9) EROSION CONTROL PLAN It is our opinion that the potential erosion hazard of the sites is not a limiting factor for the proposed development. Simple erosion control methods will reduce or eliminate any potential erosion risk. Revegetation as needed should occur immediately following construction. Hazard trees may be removed as needed. If outside the building envelope,the roots should remain in place on any steeper slope. The possibility of down-slope contamination will be reduced if proper control methods are employed. A silt fence may be installed as shown on Figures 2 and 3 and other control methods, such as swales and baled straw are practical. No re-contouring of the site will occur. It is assumed surface drainage will be directed into the flats below the residence during construction. Straw, hay, or jute matting shall be used to cover the exposed soils until permanent vegetation is established. All slopes should be seeded as soon as practical to facilitate the development of a protective vegetative cover, or otherwise protected. Surface water should not flow toward or over any steep slopes. Drainage pipes should not daylight on any steep slopes. A revegetation plan should not be required. When residential plantings or any plantings on the periphery of the residential area and the slopes are planned, native species should be considered as the primary vegetation in areas away from lawn and ornamental plantings. Shallow rooted species, such as grass, should be planted closer than 10 feet from underground drainages. Densely rooted evergreen shrubs are preferable than tree species on slopes greater than 15% gradient. Tall trees may become unstable in wet soils under high wind conditions. In general,the steep sides of the ravine should be left in a natural condition unless erosion or sloughing eventually pose a hazard to the residence. 10) ON AND OFFSITE IMPACTS There should be no notable on- or offsite impacts if the project is completed according to the recommendations of this report and in accordance with all regulations and to the high standards and practices of the building contractor. No geotechnical impact is anticipated in the construction of the residence at either location. AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 13 Phone#:(360)491-5155 Cell#:(360)481-6677 ALL AMMCA OTECUMC AL 11) FINAL DEVELOPMENT CONDITIONS All final conditions will follow the design by the Engineer of Record and compliance with all regulatory agencies. If this and the above recommendations are followed, final development conditions will be achieved. 12) STRUCTURAL MITIGATION There is no structural remediation to be done. 13) SITE PLAN Please see Figure 2. CONCLUSIONS AND RECOMMENDATIONS Based on the results of the site reconnaissance, subsurface observations, and our experience in the area, it is our opinion that the proposed site is suitable for the proposed development. The proposed structure would not undermine adjacent slopes. The site likely near the water table and design and construction must bear this in mind in design and building. Disturbance of vegetation within the parcel should be managed to avoid possible erosion. PROVISIONS GENERAL We have prepared this report for the exclusive use of RJ Peabody, Inc and their authorized agents for the proposed improvements in Mason County, Washington. Site inspections, research, and mapping have culminated in this report. This report is intended to meet the requirements of the Mason County Resource Ordinance. This report does not specify setbacks for: line-of-sight setbacks,FWHCA setbacks, eagle tree setbacks,wetland setbacks, or property line setbacks. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. No warranty or other conditions, expressed or implied, should be understood. Clients and property owners must understand that, while a slope may be found to have an acceptable Factor of Safety related to deep-seated mass wasting, surficial failure and landslides can and do occur on steep slopes. The property owners should monitor the stability of their property following construction. Moreover, acceptable Factors of Safety do not guarantee there cannot be failures. It is the responsibility of the property owners to understand that there are always risks in building on or near steeply sloped areas. AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 14 Phone#: (360)491-5155 Cell#:(360)481-6677 Ack oCRIL CONTRACTORS ARE RESPONSIBLE FOR SITE SAFETY ON THEIR OWN CONSTRUCTION PROJEC TS Our geotechnical recommendations are not intended to direct the contractor's procedures, methods, schedule or management of the work site. The contractor is solely responsible for job site safety and for managing construction operations to minimize risks to onsite personnel and to adjacent properties. READ THESE PROVISIONS CLOSELY Some clients, design professionals, and contractors may not recognize that the geoscience practices engineering (geotechnical engineering or geology) are far less exact than other and natural science disciplines. This lack of understanding can create unrealistic expectations that could lead to disappointments, claims and disputes. All American Geotechnical includes these explanatory "limitations"provisions in our reports to help reduce such risks. APPENDIX References USGS Seismic Design Specifications Slope Models Figure 1.Vicinity Map Figure 2. Site Plan Figure 3.Erosion Control Notes. AAG20 067 8947 Buttonwood Lane NE,Olympia,WA 98516 15 Phone#:(360)491-5155 Cell#:(360)481-6677 ALL m GroncKNICAL REFERENCES M"s DeLorme 3-D ToP oQuads(2002),Source Data USGS,Yarmouth,Maine. Dragovich,Logan,Walsh, and Schasse(2002),Geological Map of Washington—Northwest Quadrant(Geological Map GM- 50),published by Washington State Department of Natural Resources. Palmer, Magsino, Poelstra, Bilderback, Folger, and Niggemann (September 2004), The Liquefaction Susceptibility Map of Mason County, Washington,published by Washington State Department of Natural Resources. County, and Ni emann Palmer, Magsino, Bilderback, Poelstra, Folger, gg (September 2004), The Site Class Map of Mason Washington,published by Washington State Department of Natural Resources. Polenz, Michael et al., (2009); Geologic Map of the Belfair Lake 7-5-minute Quadrangle, Mason County, Washington;DNR Open File Report 2009-07 Rogers, A. M., Walsh, T. J., Kockelman, W. J., and Priest, G. R. (1996), Map showing known or suspected faults with quaternary displacement in the Pacific Northwest, published by U.S. Geological Survey OFR 91441-0, Plate 1, scale 1:2,000,000. PUBLICATIONS ASTM International(2005),Annual Book of Standards 2015,Section 4, Volume 4.08,published by ASTM International,West Conshohocken,Pennsylvania. Bloom(1991),Geomorphology,published by Prentice-Hall,Inc.,Upper Saddle River,New Jersey. Kollmorgen Instruments Corporation (1994), Munsell Soil Color Charts (1994 Revised Edition), published by Macbeth Division of Kollmorgen Instruments Corporation,New Windsor,New York. McCarthy(1993),Essentials of Soil Mechanics and Foundations,published by Prentice-Hall,Inc.,Upper Saddle River,New Jersey. Ness,Fowler,Parvin(1960),The Soil Survey of Mason County, Washington, USDA Soil Conservation Service,in cooperation with the United States Department of Agriculture, and Washington Agricultural Experimental Station, and the Soils Conservation Service. Parks, Neal, Koloski, Laprade, Molinari, Butler, and Lorentson (November 2006), Guidelines for Preparing Engineering Geology Reports in Washington,published by Washington State Geologist Licensing Board,Olympia,Washington. WF_RSITES Mason County Government Information Services (http://www.co.mason.wa.us) Mason County Codes,Ordinances,and Regulations oAtp://www.co.mason.wa.us/code) Puget Sound Lidar Consortium (http://pugetsoundlidar.ess.washington.edu/lidardata/index.html) AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 16 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMMUCAN GEOTECHNICAL Slope Stabilization Erosion Control Using Vegetation A Manual of Practice for Coastal Bluff (http://www.ecy.wa.gov/biblio/9330.html) Vegetation Management Guide for Puget Sound Bluff Property Owners (http://www.ecy.wa.gov/biblio/9331.html) United States Department of Agriculture Natural Resource Conservation Service OM:HsoildatamarLnres.usda.gov) Washington Administrative Code (http://apps.leg.wa.gov/wac� Washington Department of Ecology (http://apps.ecy.wa.govlweMog) (https://fortress.wa.gov/ecy/coastalatlas/viewer.htm) AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 17 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL Am c GEOT-MMICAL 2015 AASHTO DESIGN SPECIFICATIONS (\TC Hazards by Location Search Information National Park ` Redmond Coordinates: 47.454,-122.848 206f "Seattle o Elevation: 206 it - Olympic Timestamp: 2020-08-M20:04:52.004Z National Forest Kent si ye o Hazard Type: Seismic A Tacoma Reference IBC-2015 pion `, oPuYV!Iip Document GO g +#'" : it Map.Reportnmapertor Risk Category: ill Site Class: D MCER Horizontal Response Spectrum Design Horizontal Response Spectrum Sa(g) Saf9) 1.40 120 0.80 1.0D 0.60 0.80 0.60 0.40 0.40 0.20 0.20 0.00 0.00 0 5 10 15 Period(s) 0 5 10 15 Period(a) Basic Parameters Name Value Description SS 1.468 MCER ground motion(period=0.2s) SI 0.687 MCER ground motion(period=1.0s) Sµs 1.468 Sne-modified spectral acceleration value SMf 0,88 Site-modified spectral acceleration value SD8 0.979 Numeric seismic design value at 0.2s SA SDI 0.587 Numeric seismic design value at 1.0s SA -Additional information Name Value Description SDC D Seismic design category Fa 1 Site—punmuon factor at 0.2a FV 1.5 Site amplification factor at 1.0s CRS 0.969 Coefficient of risk(0.2s) CRt 0.933 Coefficient of risk(1.es) 8117f2020,1:04 PM AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 18 Phone#:(360)49 1-5 15 5 Cell#: (360)481-6677 GrAOTECHNICAL PGA 0.608 MCEG peak ground acceleration FpGA 1 Site amplification factor at PGA PGAM 0-608 Site modified peak ground acceleration TL 16 Long-period transition period(s) SsRT 1.468 Probabilistic risk-targeted ground motion(02s) SsUH 1.515 Factored uniform-hazard spectral acceleration(2o/probability of exceedance,in 50 years) SsD 2.972 Factored deterministic acceleration value(0.2s) Si R T 0.587 Probabilistic risk-targeted ground motion(1.0s) S1UH 0.629 Factored uniform-hazard spectral acceleration(2%probability of exceedance in 50 years) SID 0.95 Factored deterministic acceleration value(1As) PGAd 1.063 Factored deterministic acceleration value(PGA) The results indicated here DO NOTreflect any state or local amendments to the values orany delineation lines made during the building code adoption process.Users should confirm any output obtained from this tool with the local Authority Having Jurisdiction before proceeding with design. Disclaimer Hazard loads are provided by the U.S-Geological Survey Seismic Design Web Services. While the information presented on this website is believed to be correct,ATC and its sponsors and contributors assume no responsibility or liability for its accuracy.The material presented in the report should not be used or relied upon for any specific application without competent examination and verification of its accuracy,suitability and applicability by engineers or other licensed professionals.ATC does not intend that the use of this information replace the sound judgment of such competent professionals,having experience and knowledge in the field of practice,nor to substitute for the standard of care required of such professionals in interpreting and applying the results of the report provided by this website.Users of the m this website does not imply approval by the governing I formation from this website assume all liability arising from such use.Use of the output of site described b latituoeilon itude location in the building code bodies responsible for building code approval and interpretation for the building s� Y 9 report. 811712020,1:04 PM AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 19 Phone#: (360)491-5155 Cell 4:(360)481-6677 ALL Amr,&pjc.AN GtoucuNICAL SLOPE MODELS STATIC MODEL A—A' 0 is ci ui co ID C3 0) VJ �.�g g V g� . a-- X- Z CZ w E co S S E o cQi 8 1 ac9 .0 9 N S O.. m (53 CL U d C- a OOO � � V Z �J o d m • m 2gi O� AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 20 Phone#: (360)491-5155 Cell#: (360)481-6677 d Material Keys NVasbon Sl de be conud Depub O fit-.00 e25 g,1 01 O f7 O, J C7 1,%soa 300 O 00 J 250 w � � p p 1500 p I Lh D (D O Analyss � 150 Multiple Stability Analysis Method, 9lshopSimplilied Strlace: Circular w , rn Y Results i 00 00 100 GiticalFaGora(Safety, 279 O1 0 50 100 150 200 250 300 GALENA amJmB.lo W19d.17 Aug 2020 Praessed: 17 Aog 2020 Proiect JR Peobody,Schooner Place Analysis 2 Dynamic A-A'Line File:C: HAmericanGedechrrcaXtbraFlleOM Peabody SchoonerPiaveDyra*Agmf AllArnerieanGeoieehnieal,irlV f� , N A o CHI FIGURES FIGURE 1 VICEMY MAP 122'53.000'W 122*52.000'W 122°51.000'W 122°50.000'W NlG584 122°49.000'NJ i Z 00 G x � / pei,lap1 �� 9�1 � - ❑8d � �� z 1 � e l O ¢9 AR PM ,�- 41 ec _ �f� �t I aIf, Cove o •azvA if � MitU-. '� � / 1 WCSSq 1._?2_. 7 .i00'�Sx o49.000'W 122,53.000'W 122°520'W 0 122`51.050'W I 22`50.000'W w o t000FEET 0 :aa Iwo"TERS 145? hi¢ted fromTO.'0!5=0 Q1\z<iemt GeX Mls.Hdknxs f�--Favor AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 22 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AiMERICAN GOT' NIC` FIGURE 2. STTE PLAN AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 23 Phone#:(360)491-5155 C611#:(360)481-6677 ALL AmnicAN oT cBNIcA FIGURE 3. EROSION CONTROL NOTES AAG20-067 8947 Buttonwood Lane NE,Olympia,WA 98516 24 Phone#:(360)491-5155 Cell:#:(360)481-6677 FILTER FABRIC MATERIAL W'WIDE ROLLS USE STAPLES OR WIRE RING TO ATTACH FABRIC TO WIRE PX'!J(710AUGE WIRE FAMIC OR EOLIVALENi GENERAL EROSION CONTROL NOTES: r 1. EROSION CONTROL MEASURES SHALL BE IN PLACE PRIOR TO THE BEGINNING OF CONSTRUCTION.THE PROJECT ENGINEER AND THE COUNTY N-V SHALL INSPECT AND APPROVE THE INSTALLATION OF 112 INCH MINIMUM DIAMETER STEEL ROD EROSION CONTROL MEASURES PRIOR TO BEGINNING CONSTRUCTION. (STRAP)CLAMPED SECURELY TO PIPE , 2.EROSION CONTROL MEASURES ARE NOT LIMITED TO THE ITEMS e'66AX ON THIS PLAN.THE CONTRACTOR IS RESPONSIBLE FOR THE ON TIGHTLINE 4 INCH INSTALLATION AND MAINTAINANCE OF ALL EROSION CONTROL MEASURES. MINIMUM,B INCH SUGGESTED NO SILTATION OF EXISTING OR PROPOSED DRAINAGE FACILITIES SHALL BE ALLOWED.CARE SHALL BE TAKEN TO PREVENT MIGRATION 27W WOOD POSTS,STANDARD OR BURP BOTTOM OF FILTER OF SILTS TO OFF SITE PROPERTIES. 'TI t•�� •�h�,� $pOM 1p BETTER OREOUALALTERNATE: MATERIAL IN rXtr TRENCH I: `�"• •+r,;• AC/NG Fes, STEEL FENCE POSTS 3.THE CONTRACTOR SHALL MAKE DAILY SURVEILLANCE OF ALL EROSION CONTROL MEASURES AND MAKE ANY NECESSARY REPAIRS OR ADDITIONS 'e'"li. 'y,:a-' N, '• TO THE EROSION CONTROL MEASURES.THE CONTRACTOR SHALL PROVIDE 4A ADDITIONAL EROSION CONTROL MEASURES AS DETERMINED NECESSARY w`�'F,i1., M:Y.•Ft.�•" yi y;... BY THE COUNTY INSPECTOR AND/OR THE PROJECT ENGINEER FAILURE FILTER FABRIC B' TO COMPLY WITH ALL LOCAL AND STATE EROSION CONTROL y �L_�•� ��, - �1:••`I p•�T REQUIREMENTS MAY RESULT IN CIVIL PENALTIES BEING LEVIED N` `• •f -"� ~. ��' 2./(2'%14 GAUGE WIRE Yir'•bl•?4�'yi 'S�Lii•j�i.;%; )�.�1'e114 AGAINST THE CONTRACTOR AND/OR PROJECT OWNER. "�, I[-•: �'^ 5ti u�.,' h�:M FABRIC OR EOUtVALEM ' i AS;.></nw ♦�v4<Ae�dF n ,Cs•y'«I' 4.DURING THE WET SEASON(NOVEMBER TO MARCH)ALL DISTURBED SOILS ",#•-",�.'s��:�f t�'` r+'5��.,- 1•Tpy��i�1r•'•�kl'r GROUND SURFACE 5'-0' ,t+ SMALL BE M A MEASURES WITHIN 48 HOURS AFTER STOP OF WORK.EROSION CONTROL MEASURES SHALL INCLUDE,BUT NOT BE LIMITED TO, •> e!.1c•R�i.. •i- :Afi�,r-� GRAVEL SO SID IN TRENCH 1p• COVERING THE EFFECTED AREA INCLUDING SPOIL PILES WITH •,,'��♦_. >.4� AND E BOTH SIDES OF FILTER PLASTIC SHEETING,STRAW MATTING,JUTE MATTING,STRAW MULCH, FENCE FABRIC ON THE SURFACE B'MI OR WOOD CHIPS.SEEDING OF THE DISTURBED AREAS SHALL TAKE • PLACE AS WEATHER PERMITS. TIGHTLINE ANCHORED WITH TWO, 2•X4 WOOD POSTS 5.ALL SEEDED OR SODDED AREAS SHALL BE CHECKED REGULARLY 3 FOOT REBAR LENGTHS OR BOLTS, ALT:STEEL FENCE POSTS TO MAKE SURE VEGETATIVE COVERAGE IS COMLETE.AREAS SHALL BE REPAIRED,RESEEDED,AND FERTILIZED AS REWIRED. FILTER FABRC FENCE NOTES: TE S.TRACKING OF SOIL OFFSITE WILL NOT BE ALLOWED.IF ANY SOIL IS 1.FIL R FABRIC BHrLLL BE PURCHASED IN A CONRNUOU9 ROLL CUT TO THE LENGTH OF THE BARRIER TO AVOID USE OF JOINTS.WHEN JOINTS TRACKED ONTO A COUNTY STREET,IT SMALL BE REMOVED BY THE END ARE NECESSARY,FILTER CLOTH SHALL BE SPLICED TOGETHER ONLY AT OF THAT WORKING DAY.ANY FURTHER TRACKING OF MUD WILL THEN A SUPPORT POST WITH A MINIMUM SINCH OVERLAP AND SECURELY BE PREVENTED BY SWEEPING OR WASHING OF THE VEHICLES TIRES FASTENED AT BOTH ENDS TO THE POST. BEFORE DRIVING ON A COUNTY STREET. 2.POSTS SHALL BE SPACED A MA MW OF a FEEF APART AND DRIVEN 7.NO MORE THAN 600 LF OF TRENCH ON A DOWNSLOPE OF MORE THAN 6 SECURELY INTO THE GROUND(MINIMUM OF M INCHES). PERCENT SHALL BE OPENED AT ONE TIME 3.A TRENCH SHALL BE EXCAVATED APPROXIMATELY S INCHES WIDE AND 12 S.EXCAVATED MATERIAL SHALL BE PLACED ON THE UPHILL SIDE OF TRENCHES. FLARE END SECTION INCHES DEEP ALONG THE LINE OF POSTS AND UPSLOPE FROM THE BARRIER jj QUARRY SMALL 4.VIiEN BrpNwRD STRENGTH FILTER FABRIC IS USED,A WIRE MESH B,TRENCH DEWATERING gEVICES SHALL BE DISCHARGED IN A MANNER THAT WILL OR ENERGY "NOT ADVERSELY AFfECi FLOWING STREAMS.DRAINAGE SYSTEMS OR Z SUPPORT FENCE SHALL BE FASTENED SECURELY TO THE UPSLOPE SIDE .+,Y?cl•::P••L• .�, T�_yD PT�•y?N"A' F DISPERSION DEVICE r ��t}ny��S +• OF THE POSTS USING HEAVY-OUTYWIRE STAPLESATLEAST I INCH OFFSITE PROPERTIES. •+.• \ y"A. T:: - �T.:`C`•' LONG,TIE WIRES OR HOG RINGS.THE WIRE SHALL EXTEND INTO THE '-c�•rY.> :•-''• "•h TRENCH A MINIMUM OF 41NGIIES AND SHALL NOT EXTEND MORE THAN 36 10.ALL STORM SEWER INLETS RECEIVING RUNOFF FROM THE PROJECT DURING INCHES ABOVE THE ORIGINAL GROUND SURFACE. CONSTRUCTION SHALL BE PROTECTED SO THAT SEDIMENT-LADEN WATER GRASSUNED SWALE SHOULD BE A WILL BE FILTERED BEFORE ENTERING THE CONVEYANCE SYSTEM. MINIMUM ONE FOOT WIDE AT THE S.THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED TO THE FENCE AN020INCHES OF FABRIC SNALL BE EXTENDED BOTTOM AND ONE FOOT DEEP WITH INTO THE TRENCH.THE FABRIC SHALL NOT EXTEND MORE THAN 36 11.ALL OFFSITE CATCH BASINS IMMEDIATELY ADJACENT TO THE SITE A MAXIMUM SLOPE OF 5 PERCENT. INCHES ABOVE THE ORIGINAL GROUND SURFACE.FILTER FABRIC SHALL SHALL BE PROTECTED FROM SILTATION. NOT BE STAPLED TO THE EXISTING TREES. MINIMUM 4 FEET 12.ALL DISTURBED AREAS SHALL BE SEEDED OR SODDED UPON COMPLETION LEVEL SECTION B.WHEN EXTRA-STRENGTH FILTER FABRIC AND CLOSER POST SPACING IS OF WORK THE CONTRACTOR SHALL BE RESPONSIBLE TO ENSURE THAT USED,THE WARE MESH SUPPORT FENCE MAP BE ELIMINATED,IN SUCH COMPLETE COVERAGE OF THE DISTURBED AREAS IS PROVIDED S THAT A CASE,THE FILTER FABRIC IS STAPLED OR WIRED DIRECTLY TO THE GROWTH OF THE VEGETATION IS ESTABLISHED, GEOTEXTILE FABRIC POSTS WITH ALL OTHER PROVISIONS OR ABOVE NOTES APPLYING T.FILTER FABRIC FENCES SHALL NOT BE REMOVED BEFORE THE UPSLOPE 13.CATCH BASINS SHALL TRAP SEDIMENT OR FILTER FABRIC MUST BE AREA HAS BEEN PERMANENTLY STABILIZED. PLACED UNDER GRATE UNTIL VEGETATION IS ESTABLISHED. B FILTER FABRIC FENCES SHALL BE INSPECTED IMMEDIATELY AFTER EACH RAINFALL AND AT LEAST DAILY DURING PROLONGED RAINFALL ANY REQUIRED REPAIRS SHALL BE MADE IMMEDIATELY. All American Geotechnical,Inc. Drawn By: Erosion Control Notes 12330-52-00019 8947 Buttonwood Lane NE BWJ Proposed Garage PemTit Number. Parcel Number. P1B b 8/17/20 Mason County Peabody,Olympia,Washington 98516 �' Applicmlt Name: JR P y,Inc. Site Address: NE 71 Schooner Place 3 Revisions: Belfair,Washington NOTES / This is not a survey. This map is a presentation of information — from county,state,and federal agencies,client provided a`0°t Was information,and onsite observations;for discussion purposes of the report with which this map is included. S'�u•to tv Water for the site is community sourced. .243 / s�sed Geoff°. Curtis Dean Cushman b oN N m N N T st Pits am e 3 NE Schooner A� Rd �' r p e Prgpose a e.t•6, i D Ew Site Geology �/ rlp y l a ,o � a � Qgic Vashon Stade ice Silt contact deposits(Pleistocene) / Fgnce as S It / ,Needed F nce as Site soil i eded ' Ee—Everett gravelly oamy sand,/ 5 to 15 percen slopes 2p0\\ All American Geotechnical,Inc. Project Drawn By: Site Plan permit Number: Parcel Number: 12330-52-00019 Figure 8947 Buttonwood Lane NE Number: BWJ 8/17/20 Proposed Home Olympia,Washington 98516 AAG20-067 Belfair,Washington Applicant Name:JR Peabody,Inc. Site Address: NE 71 Schooner Place 2 Revisions: IL -- - - — -- - - - - --- r GEOW20- �v7 Mason County Review Checklist for a Geotechnica) Report Instructions: This checklist is intended to assist Stafffin the review of a Geotechnical Report. The Geotechnica(Report.is reviewed for completeness with respect to the Resource Ordinance. if an item is found to be not applicable,the Report should explain the basis for the conclusion.The Report is also reviewed for clarity and consistency. If the drawings, discussion, or recommendations are not understandable,they should be clarified. If they do not appear internally consistent or consistent with the application or observations on site, this needs to be corrected or explained. If resolution is not achieved with the author, staff should refer the case to the Planning Manager or.Director. Applicant's Name: Permit#: arcel#: '000 Date(s)of the Documents)reviewed: tvZ 1. (a) A discussion of general geologic onditions in the vicinity of the proposed development., OK?—sue Comment: (b) A discussion f specific soil types OK?_ Comment: (c).A discussion of ound water conditions OK? Comment: (d) A discussion of the upslope geomorphology OK?_��Comment: (e) A discussion of he location of upland waterbodies and wetlands OK? Comment: (f) A discussion o history of landslide activity in the vicinity, as.available in the referenced maps and records OK? Comment: 2. A site plan that identifies the important'development and geologic features. OK?---\Zcomment: 3. Locations and fogs of exploratory holes or probes. OK?_Comment:. 4, The area of the proposed development,the boundaries of the hazard, and associated buffers and setbacks shall be delineated (top, both sides, and toe) on a geologic map of the site. OK?__Vtpmment: 5. A minimum of one cross section at a scale which adequately depicts the subsurface profile, and which incorporates a details of proposed grade changes. OK? Comment: 6. A description and results of slope stability analyses performed for both static and seismic loading conditions. Analysis should examine worst case failures.The analysis should include the Simplified Bishop's Method of Circles.The minimum static safety factor-is 1.5, the minimum seismic safety factor is 1.1 and the quasi-static analysis coeffients should be a value of 0.15. OK?_\ Comment: 7. (a) Appropriate estrictfons on placement of drainage features OK? �Comment: (b) Appropriate re frfctfons on placement of septic drain fields OK? Comment: (c) Appropriate restrictions on placement of compacted fills and footings. OK? ✓ Comment: Page 1 of 2 Form Effective June 2008 (d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes. QK? I/ Comment: (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes. OK? Comment: - 8. Recommendations for the preparation of a detailed clearing and grading plan which specifically identifies vegetation to be removed, a schedule for vegetation removal and replanting, and the method of vegetation removal. OK? ✓ Comment: 9. Recommendations for the preparation of a detailed temporary erosion control plan which identifies the specific mitigating easures to be implemented during construction to protect the slope from erosion, landslides and harmful c nstruction methods. OK? Comment: 10. An analysi f both on-site and off-site impacts of the proposed development. OK? Comment: 11. Specifications of final development conditions such as,vegetative management, drainage, erosion control, and buffer wi s. OK? Comment: 12. Recommens for the preparation of structural mitigation or details of other proposed mitigation. OK? ndat�Comment: 13. A site map drawn to scale showing the property boundaries, scale, north arrow, and the location and nature of existing proposed development on the site. OK? aComment: Are the Documents signed and stamped? By.whom? License#: Li ease type: LP,27� FIRST REVIEW pproved ❑ Need more info. If not approved, what is the next action/recommendation for further action? . Reviewed by , on Time spent in review: SECOND REVIEW/'UPDATE ❑ Approved ❑ Need more info. Reviewed by , on . Time spent in second review. THIRD REVIEW/UPDATE ❑ Approved ❑ Need more info. Reviewed by , on .Time spent in third review: Disclaimer. Mason County does not certify the quality of the work done in this Geotechnical Report. Page 2 of 2 Form Effective June 2008 6 ` I 01E0 2-0 fO - -3100-7—1 PLANNING �. 2.620 - o aG MASON COUNTY t t.0 �iittal Checklist COMMUNITY SERVICES E I V E D � Building,PWnnlnry Environmental Health,Community Health Geotechnical R� AUG 2 5 2020 Instructions: 615 W. Alder Street This checklist must be submitted with a Geotechnical Report and completed,signed,and stamped by the licensed professional(s)who prepared the Geotechnical Report for review by Mason County pursuant to the Mason County Resource Ordinance. If an item is found not applicable,the report should explain the basis for the conclusion. Note:Unless specifically documented,this report does not provide compliance to the International Residential Code Sections R403.1.7 for foundations on or adjacent to slopes, Section R403.1.8 for expansive soils or section 1808.7.1 of the International Building Code Section for Foundations on or adjacent to slopes. Applicant/Owner �. Parcel# j'` ,�O S2 - oo O/f Site Address /UL , (1/ i (1) (a) A discussion of general geologic conditions in the vicinity of the proposed development, Located on page(s) 7 (b) A discussion of specific soil types, Located on page(s) 7 (c) A discussion of ground water conditions, Located on page(s) 8 (d) A discussion of the upslope geomorphology, Located on page(s) 9 (e) A discussion of the location of upland waterbodies and wetlands, Located on page(s) (U� (f) A discussion of history of landslide aVity in the vicinity, as available in the referenced maps and records. Located on page(s) (2) A site plan which identifies the important development and geologic features. Located on Map(s) (9 1 /i' Z- (3) Locations and logs of exploratory holes or probes. Located on Map(s) P (4) The area of the proposed development,the boundaries of the hazard,and associated buffers and setbacks shall be delineated (top,both sides,and toe)on a geologic map of the site. Located on Map(s) C, (5) A minimum of one cross section at a scale which adequately depicts the subsurface profile, and which incorporates the details of proposed�rade changes. Located on Map(s) (6) A description and results of slope stability analyses performed for both static and seismic loading conditions. Analysis should examine worst case failures.The analysis should include the Simplified Bishop's Method of Circles.The minimum static safety factor is 1.5,the minimum seismic safety factor is 1.1, and the quasi-static analysis coefficients shogld be a value of 0.15. Located on page(s) 9-J/ (7) (a) Appropriate restrictions on placement of drainage features, Rev. February 2018 Located on page(s / (b) Appropriate restrictions on placement of septic drain fields, Located on page(s) I 1 (c) Appropriate restrictions on placement of compacted fills and footings, Located on page(s) 1 1—1 2 (d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes. Located on page(s) J Z- (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes. Located on page(s) /Z' (8) Recommendations for the preparation of a detailed clearing and grading plan which specifically identifies vegetation to be removed, a schedule for vegetation removal and replanting, and the method of vegetation removal. Located on page(s) 13 (9) Recommendations for the preparation of a detailed temporary erosion control plan which identifies the specific mitigating measures to be implemented during construction to protect the slope from erosion, landslides and harmful construction methods. Located on page(s) 13 (10) An analysis of both on-site and off-site impacts of the proposed development. Located on page(s) 13 (11) Specifications of final development conditions such as, vegetative management, drainage,erosion control,and buffer widths. L/ Located on page(s) t 7 (12) Recommendations for the preparation of/structural mitigation or details of other proposed mitigation.T Located on page(s) ) (13) A site map drawn to scale showing the property boundaries, scale, north arrow, and the location and nature of existing and proposed development on the site. Located on Map(s) 1 I l^IGU I, CU 4i's !J Cosh tig d 4z hereby certify under penalty of perjury that I am a civil engineer licensed in the State of Washington with specialized knowledge of geotechnical/geological engineering or a geologist or engineering geologist licensed in the State of Washington with special knowledge of the local conditions. I also certify that the o h Geotechnical Report, dated i� p /P and entitled A,o li3kl'N,�s& 71 h oc-". I fctce, meets all the requirements of the Mason County Resource Ordinancej dos`i-f Geologically Hazardous Areas Section, is complete and true,that the Engineering Geologist �i 2439 c, assessment demonstrates conclusively that the risks posed by the 0 essd Gep\o landslide hazard can be mitigated through the included geotechnical Curtis Dean Cushman design recommendations,and that all hazards are mitigated in such a (Signature and Stamp) manner as to prevent harm to property and public health and safety. Page 2 of 2 Disclaimer.Mason County does not certify the quality of the work done in this Geotechnical Report.