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Home My WebLink AboutGEO2024-00071BLD2024-00816 - BLD Engineering / Geo-tech Reports - 7/2/2024 C-7Eoa 09 -Cro7 l PLANNING GEOTECHNICAL REPORT RESIDENTIAL DEVELOPMENT SITE 116 NE LARSON LADE ROAD BELFAIR, WASHINGTON PREPARED FOR HOMES AND DEVELOPMENT NORTHWEST, INC. BY ALL AMERICAN GEOTECHNICAL OLYMPIA, WASHINGTON JULY 212024 MASON COUNTY Submittal Checklis` COMMUNITY SERVICES Geotechnical Report EArsdmy Planning,to�w ,re%l Health,to w� ,q HeaRh Instructions: 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 lntemational 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 Homes and Development Northwest, Inc. Parcel# 12331-50-00006 Site Address 116 NE Larson Lake Road Belfair, Washington (1) (a) A discussion of general geologic conditions in the vicinity of the proposed development, Located on page(s) 6 - 7 (b) A discussion of specific soil types. Located on page(s) 7 - 8 (c) A discussion of ground water conditions, Located on page(s) 8 (d) A discussion of the upslope geomorphology, Located on page(s) 8 (e) A discussion of the location of upland waterbodies and wetlands, Located on page(s) 8 (f) A discussion of history of landslide activity in the vicinity, as available in the referenced maps and records. Located on page(s) 8 (2) A site plan which identifies the important development and geologic features. Located on Map(s) Figure 2 pages 8 and 24\ (3) Locations and logs of exploratory holes or probes. Located on Map(s) Figure 2 pages 8 and 24 (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) Figure 2 pages 8 and 24 (5) A minimum of one cross section at a scale which adequately depicts the subsurface profile, and which incorporates the details of proposed grade changes. Located on Map(s) Figure 2 pages 9 and 24 (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 should be a value of 0.15. Located on page(s) Figure 2 pages 9 - 10 and 24 (7) (a) Appropriate restrictions on placement of drainage features, Rev. February 2018 Located on pages 11 (b) Appropriate restrictions on placement of septic drain fields. Located on page(s) 11 (c) Appropriate restrictions on placement of compacted fills and footings, Located on page(s) 11 -12 (d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes. Located on page(s) 12 (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes. Located on page(s) 12 (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) 12 (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. Located on page(s) 13 (12) Recommendations for the preparation of structural mitigation or details of other proposed mitigation. Located on page(s) 14 (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) Figure 2 pages 14 and 24 Curtis D Cushman 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 Geotechnical Report, dated July 2, 2024 and entitled fog Residential Development Site 116 NE Larson Road Belfair, Washington meets all the requirements of the Mason County Resource Ordinance, 7-11 Geologically Hazardous Areas Section, is complete and true, that the C Engineenng Geologist Zv1y assessment demonstrates conclusively that the risks posed by the 2439 landslide hazard can be mitigated through the included geotechnical SI'd Geo` design recommendations, and that all hazards are mitigated in such a CUI`iS Dei - ' -':] manner as to prevent harm to property and public health and safety. ignafu�e and Stamp) Page 2 of 2 Disclaimer: Mason County does not certify the quality of the work done in this Geotechnical Report. ALL AMERICAN GEOTECHNICAL CONTACT INFORMATION PREPARER INFORMATION AAG PROJECT NUMBER: AAG24-070 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: HOMES AND DEVELOPMENT NORTHWEST,INC. TELEPHONE: (253)514-3915 BILLING ADDRESS: HOMES AND DEVELOPMENT,INC. P.O.Box 565 BURLEY,WA 98322 CONTACT: MEGAN GJERTSEN TELEPHONE: (253)514-3915 SITE ADDRESS: 116 NE LARSON LAKE ROAD BELFAIR,WASHINGTON 98528 EMAIL(CONTACT) MEGANGJERTSEN@GMAIL.COM PARCEL NUMBER 12331-50-00006 GPS LOCATION: 47.438 -122.865 dd AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 2 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL SCOPE OF UNDERSTANDING HOMES AND DEVELOPMENT NORTHWEST,INC. P.O.BOX 565 BURLEY,WA 98322 RE: GEOTECHNICAL REPORT PROPOSED RESIDENCE 116 NE LARSON LAKE ROAD BELFAIR,WASHINGTON 47.438 -122.865(DD) PARCEL: 12 331-50-00006 JULv 2,2024 Dear HDNW, Inc.: Homes and Development Northwest Inc. (client) through Megan Gjertsen of HDNW (contact) hired All American Geotechnical, Inc. (AAG)in June,2024 to do a geotechnical report for a residential property on a parcel 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 west of Belfair in Mason County, Washington. The site is planned to be developed with a single-family manufactured home to be sited on a previous mobile home site with existing utilities. This report will demonstrate the area planned for the residence is suitably in compliance with Factors of Safety for a Landslide Hazard Area. As per client request, we did a relevant site visit and a search of public documents. A copy of this report 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. 4 Was Respectfully Submitted, °, h�� f ALL AMERICAN GEOTECHNICAL,INC. o� I 71 - -' -^9 ernng Geokyist 2439 \Giurtis D.Cushman,L.G., L.E.G. Gpo,oc Senior Engineering Geologist Curtis [dean (7r-,b nan AAG24-070 8947 Buttonwood Lane NE,Olympia, WA 98516 3 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL TABLE OF CONTENTS SCOPE OF UNDERSTANDING 3 1) SITE CONDITIONS 5 SURFACE CONDITIONS 5 A) SITE GEOLOGY 6 B) SOIL 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 9 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 REFERENCES 16 APPENDIX 17 DOWNSLOPE WELL LOG 18 LIDAR IMAGERY 19 ASCE7-16 SEISMIC DESIGN SPECIFICATIONS 20 SLOPE MODELS 21 STATIC MODEL A-A' 21 DYNAMIC MODEL A-A' 22 FIGURES 23 FIGURE 1 VICINITY MAP 23 FIGURE 2. SITE PLAN 24 FIGURE 3. EROSION CONTROL NOTES 25 AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 4 Phone#:(360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL INTRODUCTION This report summarizes the results of our geotechnical study of the parcel herein described. The parcel is 0.28 acres in area and is a right-triangle long to the northwest-southeast with the 90°angle to the southwest, cut concave by the cul-de-sac at the end of a spur off NE Larson Lake Road. The parcel is currently partially developed. Access would be by the spur from NE Larson Lake Road which turns off of State Highway 3. Our understanding of the project is based on information from the client. In general,the parcel is on a slope descending southeast from the cul-de-sac,although north of the access it descends moderately to the south. There is a platform, partially of fill, previously for a mobile home, where the slope bends from descending south to southeast. The slope is steepest southeast of the proposed manufactured home site on this platform. The slope is overall irregular and there are hazard slopes on the parcel but mainly off it that exceed 40%. The elevation of the parcel is highest at over 95 feet above msl at the northern tip of the parcel and descends to 40 feet high at its eastern tip. The proposed residence location will be in the area of the 80 to 85 foot contours in the center northeast of the parcel on the platform. 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. 6. Slope modelling. The slope on the east side of the parcel exceeds of 40% and is greater in height than 10 feet. It is within 300 feet of the proposed building site. This is considered a Landslide Hazard Areas (LHA) Therefore, Mason County requires that a geotechnical report be prepared in accordance with the Mason County Ordinance; 8.52 Resource Ordinance. 8.52.140 Geologically hazardous areas. 1) SITE CONDITIONS SURFACE CONDITIONS The proposed location for the residential development is on a plateau above Hood Canal and is part of the common ridge and scour terrain of the continental glaciation except it has been heavily altered by development and some of the original topography is obscured. While there some older conifers on the parcel, notable near the cul-de-sac and growing north of it, much of the parcel,notably on the southeast side, is a wild blackberry patch with several juvenile firs fringing it with a few alders present. The blackberry tangles obscure a retaining wall of uncertain height running AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 5 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMEWCAN GEOTECHNICAL across the parcel southwest to northeast somewhat to the east of the building site which has been backfilled to provide part of the platform referred to above. Blaise Jelinek E.I.T. of AAG conducted a site reconnaissance on June 13,2024. 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. The trees are generally straight and vertical showing little or no signs of slope movement. A) SITE GEOLOGY The site is mapped as Qgic— Vashon Stade glacial ice-contact deposits and is described as: Geologic Unit Symbol: Qgic Geologic Unit Age: Pleistocene Geologic Unit Name: Vashon Stade glacial ice-contact deposits Publication Source: WGS Publication Number: OFR 2009-7 Quadrangle Name: Belfair Feature Link: WGS I OFR 2009-7 1 Belfair I Qgic 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 Age: Pleistocene Lithology: continental glacial drift Age-Lithology: Pleistocene continental glacial drift The Qdic is the designation found on the Geologic Map of the Belfair 7.5-minute Quadrangle, Mason, Kitsap, and Pierce Counties Washington by Polenz, Michael et al.; 2009; Open File Report 2009-7.What was seen in the field was sand in varying proportions with gravel and silt. The deposits seen on site are likely SP Poorly graded gravelly sand with silt. The glacial deposits are firm and suitable for construction. Clay is unlikely. There are no nearby folds or faults although some of the latter,small-scale possible faults,are mapped east of Belfair. The closest major fault is the Tacoma fault zone that is to the south near Allyn, Washington. 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, AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 6 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMEWAN GEOTECHNICAL low levels of seismic activity are not uncommon and there is always the possibility of a major shock. In the case of a Cascadia event,the site is mapped on the Mason County GIS a in a zone with a potential MMI of 7, Very Strong. The parcel is mapped a Stable in the DOE Coastal Zona Atlas. The DNR 2007 Hazard Zone maps most of the parcel as Very High,but this was reduced in the DNR 2009 Landform mapping to High in a much reduced area in the east part of the parcel corresponding to the tighter contours. B) SOIL The soils in the areas of the proposed development is described by the USDA Web Soil Survey as: Ib—Indianola loamy sand,5 to 15 percent slopes Map Unit Setting • National map unit symbol: 2t635 • Elevation: 0 to 980 feet • Mean annual precipitation: 30 to 81 inches • Mean annual air temperature:48 to 50 degrees F • Frost free period: 170 to 210 days • Farmland classification: Prime farmland if irrigated Map Unit Composition • Indianola and similar soils: 85 percent • Minor components: 15 percent • Estimates are based on observations, descriptions, and transects of the mapunit Description of Indianola Setting • Landform: Terraces,kames,eskers • Landform position (three-dimensional): Riser • Down-slope shape: Linear • Across-slope shape:Linear • Parent material: Sandy glacial outwash Typical profile • Oi- 0 to I inches: slightly decomposed plant material • A - 1 to 6 inches: loamy sand • Bwl - 6 to 17 inches: loamy sand • Bw2- 17 to 27 inches: sand • BC-27 to 37 inches: sand • C-37 to 60 inches: sand AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 7 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL 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 99.90 in/hr) • Depth to water table: More than 80 inches • Frequency of flooding:None • Frequency of ponding.None • Available water supply, 0 to 60 inches: Low(about 3.9 inches) This soil was what was seen on site. Note the drainage. C) GROUND WATER CONDITIONS There is no evidence of flowing water. There was no evidence of active surface erosion. D) UPSLOPE GEOMORPHOLOGY There is a rise along the ridge to a top of 150 feet over 400 feet to the north-northeast. This poses no threat to the property. E) UPSLOPE WATERBODIES AND WETLANDS There are none. F) LANDSLIDE ACTIVITY Landslides are mapped as small features alongside Mission Creek well to the west and north of the client parcel. The parcel is not threatened by such landsliding. 2) SITE PLAN Please see Figure 2 in the Appendix. 3) EXPLORATORY HOLES OR PROBES The site was surface examined on the excavated flat area, at the access,and along NE Larson Lake Road. Hand dug samples were examined on-site. The Indianola sand was consistently present. 4) PROPOSED DEVELOPMENT This will be a single-family residence, a manufactured home. AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 8 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL 5) CROSS SECTION Two cross-sections are in the Appendix. They are along line A-A', which pass through the proposed residence and evaluates the stability of largest and closest LHA. 6) SLOPE STABILTY ANALYSIS The Slope Stability Analysis is as follows following the Mason County Code of Ordinances of 2021: 8.52.140 (E)(5) (d) 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 should be a value of 0.15. Slope stability was modeled using the GALENA 6.1 program in both static and dynamic conditions (ca= 0.15). "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) is set at 0.150 g per the Mason County Code. Additional seismic design values from the ASCE7-16 (American Society of Civil Engineers) are included in the Appendix. The surface soil was field classified as a SP Poorly graded gravelly sand with silt. These units are consistent with the description of the Qgic deposits and the Indianola sandy soil. The site was modeled with a single layer. Groundwater was not 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 Unit Weight Cohesion Phi Angle Qgic-Ice contact deposits 117 100 38 Factors of safety were determined using the Bishop (semi-circular) method. 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=0.15),the computations demonstrated that the site has a safe FoS. 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. AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 9 Phone#:(360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL Table 2. Initial Positions, Variance, and Findings Anal sis Load Across Analysis Earthquake Slope to Initial Positions(.Analysis Range)lConfigurationslFactor of Number Building Envelope Type Force Building Lo«er L' er Radius Anahzed Safety Cross-Section A A' 1—_ .Static i 0.0 g !Below 1 60(55) . 188.5(57)_.1._225(60) 125,001....._._i._,.... .� Analysts 11500#160-217' .. .... s 2 ;1500#160-217' ;Dynamo_ 0.15 g ?Below - 60(55) 1188.5(57)! 225(60) 1 125,001 1 1.85 The values input were selected to be as conservative as possible so the FoS are possibly higher. The graphic output of these data is presented in the Appendix,pages 21-22. 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 Low liquefaction potential. The Site Class Map of Mason County, Washington by Palmer,Magsino,Bilderback,Poelstra,Folger,and Niggemann (September 2004) maps the area as site Class C to D. Site class C is a very dense stiff soil and soft rock and Site class D is stiff soil(nehrp classifications). GEOSEISMIC SETTING According to the Seismic Zone Map of the United States (Figure 1613.3.1(1)) contained in the 2018 International Building Code (IBC), the project site is located where the maximum spectral response acceleration is greater than 65 percent of gravity(g). We recommend following seismic factors for design purposes. • Site Class: D(stiff soil/soft rock) • Spectral response acceleration, short period(SMs): 1.632g(Fa= 1.0) • Spectral response acceleration, 1-second period(SMi): Null (F„=Null) • Peak Ground Acceleration 0.697 g 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: • �(soil friction angle) 38 degrees • Ko(at rest earth pressure coefficient) 0.384 • Ka(active earth pressure coefficient) 0.238 • Kp(passive earth pressure coefficient) 4.20 • y(soil unit weight) 117 pcf AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 10 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL 7) RESTRICTIONS A) PLACEMENT OF DRAINAGE FEATURES Drainage may be done by surface dispersions although an option would be to run a drainage tightline to an allowed drainage feature, such as a road ditch. The ground surface and pavement grades are already acceptable for drainage from the home and associated structures. Surface water runoff should be controlled by a system of curbs,berms,drainage swales,and/or catch basins and tightlined 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 USDA soil drainage class is"somewhat excessively drained,"so water will readily infiltrate for dispersion. 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 that may be applicable to this parcel.) Drainage should be such that there is no flow onto the steep slopes to the east. B) PLACEMENT OF SEPTIC DRAIN FIELDS The drain field is located as mapped on Figure 2. The drainfields will be outside the LHA. Domestic water is from a community source. C) PLACEMENT OF COMPACTED FILLS AND FOOTINGS RECOMMENDATIONS FOR SITE PREPARATION The original area proposed for the manufactured home is mostly cleared but may require some tree removal. Trees will be falled as needed for construction. Much of the site will need clearing for the septic drainfield and general improvement. The building footprint is partially inside the 50-foot vegetation buffer. However,the main construction area has already been timbered and construction may proceed if standard practices of erosion control are followed as surface vegetation is cleared. 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 AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 11 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL 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 sections 9-03.12 and 9-03.14 of the WSDOT Standard Specifications 2024. 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. D) BUFFERS The manufactured home will be just partially inside a 50-foot vegetation buffer. The area has been cleared of trees and existing septic drainfields are essentially a blackberry tangle. Construction may proceed in the area. The slopes are such that erosion should be considered as a factor but, with proper control, not a limiting factor. The LHAs,which are on the slope to the northeast shall not be disturbed. E) SETBACKS The residence location was developed previously and is shown on Figure 2. It is acceptable. 8) CLEARING AND GRADING PLAN Some timber clearing may be needed. This will be limited to trees around any development area. No grading is anticipated except to develop the foundations of the residence and driveway. "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. AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 12 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL 9) EROSION CONTROL PLAN It is our opinion that the potential erosion hazard of the sites is not a limiting factor for the proposed developments. Removal of natural vegetation will be limited to blackberries and other low scrub near the proposed home site and at the septic drainfields. Some minor amount of timbering may be needed. Simple erosion control methods will reduce or eliminate any potential erosion risk. Trees and understory growth on the LHA slope itself will not be disturbed. Revegetation as needed should occur immediately following construction. No hazard trees appear to be present. Erosion in the Indianola sandy soils is mitigated by the high rate of drainage. With adequate revegetation, the risk is low. The possibility of down-slope contamination is unlikely 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. Surface drainage should be directed away from all slope faces. 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 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 bluff 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. 11) FINAL DEVELOPMENT CONDITIONS Final development will rely on placing the manufactured home on the pre-existing site and clearing the rest of the area for development with an eye on erosion control. The drainage of the soil should be adequate for the new home. 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 may be achieved. AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 13 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL 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 development site on the client property is suitable for a residential development. The location of the residence as proposed complies with the Factors of Safety for the county code. The erosion hazard is manageable, and drainage should not pose a great problem. If timbering is necessary, it may be done as noted above and in keeping with county regulations. For erosion control,we recommend a silt fence or other erosion control measures noted above followed by revegetation. PROVISIONS GENERAL We have prepared this report for the exclusive use of Home Development Northwest and their authorized agents for development of this property 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 Code. 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. CONTRACTORS ARE RESPONSIBLE FOR SITE SAFETY ON THEIR OWN CONSTRUCTION PROJECTS 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. AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 14 Phone#:(360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL READ THESE PROVISIONS CLOSELY Some clients, design professionals, and contractors may not recognize that the geoscience practices (geotechnical engineering or geology) are far less exact than other engineering 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. AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 15 Phone#:(360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL REFERENCES MAPS DeLorme 3-D TopoQuads(2002),Source Data USGS,Yarmouth,Maine. 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. Palmer, Magsino, Bilderback, Poelstra, Folger, and Niggemann (September 2004), The Site Class Map of Mason County, Washington,published by Washington State Department of Natural Resources. 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 91-441-0,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. Kollmorgen Instruments Corporation(1994),Munsell Soil Color Charts(1994 Revised Edition),published by Macbeth Division of Kollmorgen Instruments Corporation,New Windsor,New York. 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. WEBSITES(AS ONLINE USDA WSS,WA STATE GEOLOGIC INFORMATION PORTA,MASON COUNTY GIS,DEPT OF ECOLOGY. ETC. Mason County Government Information Services (http://www.co.mason.wa.us) Mason County Codes,Ordinances,and Regulations (http://www.co.mason.wa.us/code) Puget Sound Lidar Consortium (http://pugetsoundlidar.ess.washington.edu/lidardata/index.html) United States Department of Agriculture Natural Resource Conservation Service (http://soildatamart.nres.usda.gov) Washington Administrative Code (http://apps.leg.wa.gov/wac/) Washington Department of Ecology (http://apps.ecy.wa.gov/welilog) (https://fortress.wa.gov/ecy/coastaladas/viewer.htm) AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 16 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMEWCAN GEOTECHNICAL APPENDIX Downslope Well Log LiDAR Imagery USGS Seismic Design Specifications Slope Models Figure 1.Vicinity Map Figure 2. Site Plan Figure 3. Erosion Control Notes. AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 17 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL DOWNSLOPE WELL LOG WATER VILL REPORT Start faro No. NOS1141 Unique Nell 1.6. 1 AC111214 STATE OF NASiII61011 Water RiqAt Permit N. .::..tia..............t.[Liliiaiiit U N[{Li UifSSti:tiitii iti.r(:!!:: -- •-•� .......on,r:..a.x:lf.a:eaaafa/a1 II) ONNEP:�Nae SHOW. MV I fl IK Address 4149 641M AVE M TACO". NA f1466-1I11 tj (?�f:LDCAiTOM Or NELL:i tOwtrrNAM`iis is:srirLiu[irLLtttf H...uu rrasa.a.a[fiias.raf..aa.::.Lz:::::ssarnfsf•..r.as r s:::sri-T: - So 1 4 SE 114 Stc 16 1 23 1., R 29 NN 1161 SiiELI ADDRESS Or Kit for nearest Address) ME $11 6U Nlll 41. KLFAU ............ [.i:[a...i[........a...r......r[..vi......rr...ta...+..<.....a....t.i............ (I) PROPOSED USr: DOKSllt ' (11) WILL t86 ...........t,rr.rr.T:......t.....%......1....1 ... N 14) TYPE Of WORT: Owner's Number of well llf Wort than one) Formations Describe by color, character, sire of material r and structure. and :Sow tbtttat%@, Of agoilers ad the kind 3 NEU Nit Method: IOTARY t Still nature of the material in each stratum penetrated, wtlb y :z::::::r.::a.::a::::::::-.::an f:i:a::....rata[a:::asaasataiia; at least one "try tar each Change in fdrmati0n. '— IS) 0111m1041 Oiameter of well G i#KW. _ ................................. .................. Drilled 56 1t. Depth of completed well it it. 1 MATERIAL C ..-.......L:a,.t.: ,t:,:. .....l....:i_..t...:t.aa:..:,.......... PIPE STICK-W1 run `0 O ifi) CONSTIIW I011 DETAILS• 1 FILL 1 f 3 Gating ina ailed: i ' Dia. frow •l ft. to S6 ft. MI SAN GRAVEL SONS MY I E2 O NEII[D D u. from ft. to It. ' OWSAID SOME GIAVEI KUY WATER 12 t 46 Ills ' Dia. from ft. to It. + WON SANI GRAVEL G WATER 4S f SG to ..................... .... .............I................ E Perforations: so t 1 �. type of perforator used r I t WE of perforations is. by = perforation; from ft. to ft. t ! I d perforation; Ira it. to ft. f t perforations Ira (I. to ft. , ....... .............. .................................. f I Screens: YES 1 I , O flanmfaCturrr'; Name lype STAINLESS Model ND. TELESCIDITN6 01a. i slot silt 21 Ira SI it. to 66 ft. f to eta. slot 'ate from ft. to ft. � it .......... ........ ....................1 Urarel parted: NI Sitt of gMStroI , f' Gravel Placed from. it. to ft.• d Sur fice stat: YES To what de¢th? ►1• .1t.'T s 1 1 Mattrial used in seal KITUITE r 1 .� Did anyy strata contain unmsabfe crater. MO type of water? Depth of strata ft. _ �+ G Method of staling strata off 3. !Ti::i.a•T:ti:::-:SS:.':S:t::ST.i::: ` ifl P'NiP: Ninula-tyrers Mime S ! t to Type N.P. , 3 +.r<......row♦a.a<..a...ia:.a.,....:..,..a...r.a..arr.«.....<.a,<1 1 � (1) NAtER 1Etit5: umd•surtace Neratiom � � above mean sea level it. 0 Static It.-et G ft. below top of well Due 6112I/91 + f t Z Artesian Pr►sswe IDs. per sgwre Inch Date Artesian water robtrolled by t I f wort started 11111111 Cowleled I1i21111 Os.i++::t:x::•.:::::s a..... :a::s::.•::.:::::a:ais.,::.:s.:rrsiaaa,iicuia:u sir:aar:a r.r..a i[ssu far:::::..:ss.ar.srssa ss[ar V (11 ME;E 1( M braw4orh is amount water level is lowered below 4 NEII CONSTRUCTOR CER.'irICAT10N: >% :lalic level. I constructed and/or accept respon5lbility for con- t" was a potq trst a�k. NO It yes. by vfw structiom of this weft, and its compliance with all O Yield: yet./min with it. drawdown after brs. t Washington wit construction standards. Materials used 1 and the rntormation reported abort are true to my ►est V t tnowledge and belief. W Recovery data ,� Time water level Time water level Time Water level 1 NAME NICiLSON 1RitIING iKE O (Person, firm, or corporation) (Tape or print) late of tit ADDRESS 12 -T Railer Its? Ill 4a 1a 3wd n. 11 ft. 4rowri after 1 Drs. 1 (SIG tictn,r No. IS1! Air test gal min. w/ tfm set ai It. for nrs. R Artesian flow g.p.b. late r Ceti tars � a temperature at water Was a chemical analysts made? NO i Rtylstration 00 0 C►OOIISIOM pate 481:9191 ��L�l TtTt iTiifStSiLT:i-!if!iTtt44LttiiTtftlT:a:'ifa::tT:i:'::Lf:eSSit'Li:`.i[1[iaiT:r:::t::. f ti:t::•'. _. .... r..........:...r.... oY. .e I— AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 18 Phone#: (360)491-5155 Cell#: (360)481-6677 D r � 5 ® - . MY 04 4 -, . r m CD oo ar t y wbd ? p o C7 S � �r � a.�,, Rom, _,,gyp •' 1 t, a 4 000 `°00 LA ON 41 r y - Mffbfar 4 .,ndy Maps Contributors.County of Kdsap.WA State Parks OIS,®OpenStreeNap.Microsoft Esn.Tom Tom C �O ALL AMERICAN GEOTECHNICAL ASCE7-16 SEISMIC DESIGN SPECIFICATIONS 4I1` Hazards by Location Soarch Information coord•:tams: 4rp�.a22.«e6 ft ;. E)evstwn rs« Tlmeetarrp 1024W-OIT21Dw 52= t+atard Type Gart._ R►lennce Document :C7.16 Risk Cst.gn.tr: I 6h ti�le2a do.�e Sits ryas. t' Basic Parameters stern. V.iw oaecrlphisn 5,y 1,632 %60., graurd m1Uar; orod Ll..W S, r),"2 WE,grand mc6r;P0rci1=1.vs; SAM 1,632 Ste-ludred weet-al accelvatim value svi H p Sh ry dfe.A%p #v1 ssw*orNat vW6- SM %bm N,"rc warn,_design value a 0,2s SA sw •'uN Wa.rwc sonnu_tMnq,vefue at 1,0s Sl1 'See Semen 1'.4.8 -Additional Information Blame Value Deecrnatlon Sewm amgg cowwj v S Mw wMN10abar factor at US S"W"ww-mw Now a1 t,0a --R,y C W2 CovVicra•a at raft ta,2s) CR, CM2 cowcrrlofrdk(1.0a) ;—,A CAW Urt3 Peat qr xrrd erxder 1-X1 rPf� •,1 4:.o Plrrpad:.plan l so,et P4;A C,787 S+A ancd,ed peat gpcvnd accalaraban T, •6 pr'aKxr.}d rtrtstrn+perud(s; Srq- •.632 ;s.,abeblisli:rroMfagr:ro%r"d rv6m;0.2v) 4w7H +DC8 Feaaec 0-41) ftt-w rd e4eclral ed.nlW~S2%pr(Aablily d exseederre n 50 were i 3.742 Fa•.Aawd debvrnim0t;wtwlrtaow-vakr(0 2a) S1Ri C"2 Mabee«etk du Wr2r tw gt,krd room t/,All Sttk+ CA" =..snored.ardor ne2ero Spectral scoalsraeo+r(?%p•rear,llty d 4xvwxS rco n 50 yearn) 5iD 1 j71) Pedleaa dsrternrhs`rc arCNlgtiarr+relw 11,Cs1 PGAII 1.196 isam ed detstrrtna'+r accitknow VA*(PsOA) .See Seekin 11.4,E The serM mdaraslad ham DO VOT milad any efale or,ccs+arwrawo•kt"rro vutLgs.v ww dAlr,a~Arms msdo dt rt rp the NAtrarp soft edlWltRNsaeaa.tj aratdd tenbo ey cs1Ap106feined kcim Mn tad v0 Nu iota[Au0%a*Hemp A0w)vbw ber.,m prncso.r SAM dew. AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 20 Phone#:(360)491-5155 Cell#:(360)481-6677 ALL AmimcAN GEOTEUMCAL SLOPE MODELS STATIC MODEL AW � c N � 4 N 1 x � g j �6 J J W Ali cD yt V O !7C( at di C, s J AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 21 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL DYNAMIC MODEL A-A' 1i �q N C. 75 a i � Yp yy JC pG 8 J W Z c Q J D Cp oo p C pp pp p Cp � � f�Cp O ^ R 8 OD f0 R N O N 2^ AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 22 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL FIGURES FIGURE 1 VICINITY MAP — 122°54 w w 12r,5 w w 122• 00'w 122°S '00'W YVGSB4 °50 t10'w 1 < C tc�e1E1RtrgR'LEI�' , �]i ♦#: l.afi�?e9i� f'i31-50-011006 Z � .1 N r'- b�A 2 4 y.. " .f� ref � � ' I� �r.•, ': d? , t t22•st•oo-w 12r5j-W w I2206i'W w 122"57'00'w WG584 e22050'00"W b ! KNEE • SP (�,• �111}R 1 !r �MFIFR4 (asw SM now ONN OW Wm Sawn om ow AAG24-070 8947 Buttonwood Lane NE,Olympia,WA 98516 23 Phone#: (360)491-5155 Cell#: (360)481-6677 o00a ,: 9= NOTES 3 cp a This is not a survey. This map is a presentation of a'R m information from county,state,and/or federal 7 agencies,client provided information,and onsite F 7 observations. Site Geology EARTHQUAKES Water is community sourced y o �,� Qgic— ashon Stade ice-contact deposits Ground Response Liquefaction: Low zQob—Uplifted(relic) beach terraces Site Class:C to D m a, Seismic Parameters n Sms-1.632 g(Fa=10) �� s. Site Soil Sm t=null(Fv=null) y a c PGA=0.697 g N ® lb—Indianola loamy sand, < 5 to 15 percent slope. V 0 xlaop N.V O\� N•- �P 0 —O io I � � d 1 7 yx O 7 I � I z c. I I 9 I I I I x�. I 1 I .> A sty I Cyp c a = € Q0b Z � 3 = � C y _` I I O 3 i I I m I d O 0 v 3 0 N � 1 I a z C I 3 I .. I _ _ I n� I z u Z — I m 1 o � I Was n < 7-3� P^SedGe°hoc Curtis Dean Cushman to - a FILTER FABRIC MATERIAL BP WIDERDLLS USE STAPLES OR WINE RING TO ATTACH FABRIC TO WIRE 2'XrX14 GAUGE WIRE FABRIC OR EQUIVALENT GENERAL EROSION CONTROL NOTES: Z 1. EROSION CONTROL MEASURES SHALL BE IN PLACE PRIOR TO THE BEGINNING OF CONSTRUCTION.THE PROJECT ENGINEER AND THE COUNTY SO• A/A\�GROUND ACE A\N 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 r ,,,,,,, 2.EROSION CONTROL MEASURES ARE NOT LIMITED TO THE ITEMS rMo ON THIS PLAN.THE CONTRACTOR IS RESPONSIBLE FOR THE CORRUGATED TIGHTLINE 41NCH INSTALLATION AND MAINTAINANCE OF ALL EROSION CONTROL MEASURES. MINIMUM,S INCH SUGGESTED / 1 NO SILTATION OF EXISTING OR PROPOSED DRAINAGE FACILITIES SHALL BE ALLOWED.CARE SHALL BE TAKEN TO PREVENT MIGRATION 4/A 2•X4•WOOD POSTS,STANDARD OR BURY BOTTOM OF FILTER OF SILTS TO OFF SITE PROPERTIES. r,�) ... qy TD BETTER OREOUALALTERNATE: MATERIAL IN rX17 TRENCH a; -`r'y-,r; STEEL FENCE POSTS ',1'�L. ,•�;s �/AY; ET 3.THE CONTRACTOR SHALL MAKE DAILY SURVEILLANCE OF ALL EROSION yy..� {'r T.i.,•.. CONTROL MEASURES AND MAKE ANY NECESSARY REPAIRS OR ADDITIONS '„ TO THE EROSION CONTROL MEASURES.THE CONTRACTOR SHALL PROVIDE ADDITIONAL ER0910N CONTROL MEASURES AS DETERMINED NECESSARY .• *�•�;;'S,,��; ,.yYLs+�'T`<"r»,._ BY THE COUNTY INSPECTOR AND/OR THE PROJECT ENGINEER.FAILURE h\"�''n1'+ P"•M"h*' FILTER FABRIC 8' TO COMPLY WITH ALL LOCAL AND STATE EROSION CONTROL RE OU IREMENTS MAY RESULT IN CIVIL PENALTIES BEING LEVIED ''`�'.-,.'�� w'3•"! �`�--�r 'F 2 u X14 GAUGE WIRE AGAINST THE CONTRACTOR AND/OR PROJECT OWNER. Z' '�r ::.y.^:_'•.',5.:• Cr}i-ri 4A..li'M„�'tu FABRIC OR SOUNALENT r• i n�i�t, 4J.^.� �u tr n .� •p r.4i• F•'yl i+l'•,,. 1Y •f F IiF,rb`\L P GROUND SURFACE 6'-v 4.DURING THE WET SEASON(NOVEMBER TO MARCH)ALL DISTURBED SOILS ,1.:1'y 5:w5 h• "t'.>j„\�7y `j`^ y1l+�ev��` SHALL BE STABILIZED WITHIN 4B HOURS AFTER STOP OF WORK.EROSION '+�'^.I'C%.1u..1: iw:°S.• :.� `y41nA PROVIDE are- CONTROL MEASURES SMALL INCLUDE,BUT NOT BE LIMITED TO, A. 11/r WAS GRAVEL BACKFILL IN TRENCH 12. COVERING THE EFFECTED AREA INCLUDING SPOIL PILES WITH AND ON BOTH SIDES OF FILTER PLASTIC SHEETING,STRAW MATTING,JUTE MATTING,STRAW MULCH, E>vw�'+•'��'' `~J�'4'� FENCE FABRIC ON THE SURFACE 8•AN OR WOOD CHIPS.SEEDING OF THE DISTURBED AREAS SHALL TAKE ay+ �v�r "• PLACE AS WEATHER PERMITS. TIGHTLINE ANCHORED WITH TWO, rX4•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 REQUIRED. FILTER FABRIC FENCE NOTES: 1.M ER FABRIC SINLL BE PURCHASED W A CONTINUOUS ROLL CUT TO 6.TRACKING OF SOIL OFFSITE WILL NOT BE ALLOWED.IF ANY SOIL IS THE LENGTH OF THE BARRIER TO AVOID USE OF JOINTS.WHEN JOM TS TRACKED ONTO A COUNTY STREET,IT SHALL 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&INCH OVERLAP MID 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.PGSTS SHALL BE SPACED A MAXIMUM OF 6 FEET APART AND DRNEN 7.NO MORE THAN 500 LF OF TRENCH ON A DOWNSLOPE OF MORE THAN 5 SECURELY INTO THE GROUND(MINIMUM OF 30 INCHES). PERCENT SHALL BE OPENED AT ONE TIME, 3.A TRENCH SHALL BE EXCAVATED APPROXIMATELY B INCHES WIDE AND 12 B.EXCAVATED MATERIAL SHALL BE PLACED ON THE UPHILL SIDE OF TRENCHES. LFLARE END SECTION INCHES DEEP ALONG THE LINE OF POSTS AND UPSLOPE FROM THE BARRIER. 4.WHEN STANDARD STRENGTH FILTER FABRIC IS USED.A WIRE MESH .TRENCH DEWATERING DEVICES SHALL BE DISCHARGED IN A MANNER THAT WILL QUARRY SPALL , .:'.'NOT ADVERSELY AFFECT FLOWING STREAMS.DRAINAGE SYSTEMS OR OR ENERGY %aKa,.[,'SUPPORT FENCE BHA LL BE FASTENED SECURELY TO THE UPSLOPE SIDE DISPERSION y4L,•4YJ`f,(6A4 1 1•„+h} `{=Sr^'; j1�At'-' OF THE TIEDWIRES OUSING MOG RINGSTTHWIRE STAPLES AT E WIRE 51MLL EXTEN�OTI I INCH NTO THE OFFSITE PROPERTIES. DI$PER$ION DEVICE •.,.i:, +r"1�{y..✓+.:-,4 i}��:,i(;,.-• TRENCH A MINIMUM OF 41NCHEs AND SHALL NOT EXTEND MORE THAN 36 10.ALL STORM SEWER INLETS RECEIVING RUNOFF FROM THE PROJECT DURING i .Y INCHES ABOVE THE ORIGINAL GROUND SURFACE. CONSTRUCTION SHALL BE PROTECTED SO THAT SEDIMENT4ADEN WATER GRASS-LINED SWALE SHOULD BE A 5.THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WViED WILL BE FILTERED BEFORE ENTERING THE CONVEYANCE SYSTEM. MINIMUM ONE FOOT WIDE AT THE TO THE FENCE AND M INCHES OF FABRIC SHALL BE EXTENDED 11.ALL OFF-SITE CATCH BASINS IMMEDIATELY ADJACENT TO THE SITE BOTTOM AND ONE FOOT DEEP WITH INTO THE TRENCH,THE FABRIC SHALL NOT EXTEND MORE THAN 36 SHALL BE PROTECTED FROM SILTATION. A MAXIMUM SLOPE OF 5 PERCENT. INCHES ABOVE THE ORIGINAL GROUND SURFACE.FILTER FABRIC SHALL NOT BE STAKED TO THE EXISTING TREES. MINIMUM 4 FEET 12.ALL DISTURBED AREAS SHALL BE SEEDED OR SODDED UPON COMPLETION LEVEL SECTION 6.WHEN EXTRASTRENGTH FILTER FABRIC AND CLOSER POST SPACING B OF WORK,THE CONTRACTOR SHALL BE RESPONSIBLE TO ENSURE THAT USED.THE WIRE MESH SUPPORT FENCE MAP BE ELIMINATED,IN SUCH COMPLETE COVERAGE OF THE DISTURBED AREAS IS PROVIDED 6 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. 7.FILTER FABRIC FENCES SHALL NOT BE REMOVED BEFORE THE UPSLOPE 13.CATCM BASINS SHALL TRAP SEDIMENT OR FILTER FABRIC MUST BE AREA HAS BEEN PERMANENTLY STABILIZED. PLACED UNDER GRATE UNTIL VEGETATION IS ESTABLISHED. 8.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 Permit Number: Parcel Number: 12331-50-00006 Figure 8947 Buttonwood Lane NE BWJ 7/2/24 Proposed Home Homes and Development, Olympia,Washington 98516 Revisions: Belfair,Washington Applicant Name: Northwest Inc, Site Address: 116 NE Larson Lake Rd Page 25