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HomeMy WebLinkAboutGEO2024-00023 SHR2024-00004 Variance SFR Addition - GEO General - 2/29/2024 Oleo 2o2.A4 - 060A RECEIVED FEB 2 9 2024 G EOTECHNICAL REPORT 615 W. Alder Street 3040 NE STATE HIGHWAY 300 BELFAIR, WASHINGTON PREPARED FOR LAURA AN MATTHEW HARKINS BY ALL AMERICAN GEOTECHNICAL INC. OLYMPIA, WASHINGTON August 18, 2023 ALL AMERICAN GEOTECHNICAL CONTACT INFORMATION PREPARER INFORMATION GTL PROJECT NUMBER: AAG23-082 CONTACT: CURTIS D.CUSHMAN ADDRESS: 8947 BUTTONWOOD LANE NE OLYMPIA,WASHINGTON 98516 TELEPHONE: (360)491-5155 CELL/TEXT (360)481-6677 EMAIL ADDRESS: CURTIS.CUSHMAN@COMCAST.NET CLIENT INFORMATION CLIENT: LAURA HARKINS CLIENT ADDRESS: 3040 NE STATE ROUTE 300 BELFAIR,WA 98528 CLIENT TELEPHONE (360)227-9278 CLIENT EMAIL LAURA041966@HOTMAIL.COM BILLING ADDRESS: LAURA HARKINS 3040 NE STATE ROUTE 300 BELFAIR,WA 98528 SITE ADDRESS: 3040 NE STATE ROUTE 300 BELFAIR,WASHINGTON PARCEL: 22201-51-91001 GPS LOCATION: 47.432 -122.875 AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 2 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL SCOPE OF UNDERSTANDING LAURA HARKINS 3404 NE STATE ROUTE BELFAIR,WA 98528 AUGUST 18,2023 RE: GEOTECHNICAL REPORT 3040 NE STATE ROUTE 300 BELFAIR,WASHINGTON PARCEL#22201-51-91001 47.432 -122.875 (dd) Dear Mr.ad Mrs. Harkins: All American Geotechnical, Inc (AAG) was contacted in June of 2023 by Laura Harkins (client) to do an evaluation for the above parcel. This will be in two parts, this, the geotechnical report, being the first. A CMZ study will follow. As per her request, this the geotechnical report for the parcel. We are sending a PDF copy of the report along with the checklist to the client. We appreciate this opportunity to be of service to you and we look forward to working to help complete this project safely and in compliance with the regulations and standards of Mason County. 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 numbers listed below. Respectfully Submitted, gyp,°� �aSh;n ALL AMERICAN GEOTECHNICAL Nine-ring Gaol isl ' 2439 v c�nsed G°e �° Curtis D Cushman Curtis Dean Cushman Senior Engineering Geologist AAG23-082 8947 Buttonwood Lane NE,Olympia, WA 98516 3 Phone#: (360)491-5155 Cell #: (360)481-6677 ALL AMERICAN GEOTECHNICAL TABLE OF CONTENTS INTRODUCTION 6 1) SITE CONDITIONS 6 SURFACE CONDITIONS 6 A) SITE GEOLOGY 7 B) SOIL TYPES 9 C) GROUND WATER CONDITIONS 10 D) UPSLOPE GEOMORPHOLOGY 10 E) UPSLOPE WATERBODIES AND WETLANDS 10 F) LANDSLIDE ACTIVITY 10 2) SITE PLAN 10 3) EXPLORATORY HOLES OR PROBES 10 4) PROPOSED DEVELOPMENT 11 5) CROSS SECTION 11 6) SLOPE STABILTY ANALYSIS 11 SEISMIC LIQUEFACTION HAZARD 12 GEOSEISMIC SETTING 12 LATERAL EARTH PRESSURES 12 7) RESTRICTIONS 13 A) PLACEMENT OF DRAINAGE FEATURES 13 B) PLACEMENT OF SEPTIC DRAIN FIELDS 13 C) PLACEMENT OF COMPACTED FILLS AND FOOTINGS 13 RECOMMENDATIONS FOR SITE PREPARATION 13 RECOMMENDATIONS FOR STRUCTURAL FILL 14 D) BUFFERS 14 E) SETBACKS 14 8) CLEARING AND GRADING PLAN 15 9) EROSION CONTROL PLAN 15 10) ON AND OFFSITE IMPACTS 15 11) FINAL DEVELOPMENT CONDITIONS 15 12) STRUCTURAL MITIGATION 15 13) SITE PLAN 16 CONCLUSIONS AND RECOMMENDATIONS 16 PROVISIONS 16 GENERAL 16 CONTRACTORS ARE RESPONSIBLE FOR SITE SAFETY ON THEIR OWN CONSTRUCTION PROJECTS 17 READ THESE PROVISIONS CLOSELY 17 REFERENCES 18 AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 4 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL APPENDIX 20 ASCE7-16 SEISMIC DESIGN SPECIFICATIONS 21 NEIGHBORING WELL 22 SLOPE MODELS 23 STATIC MODEL A-A' 23 DYNAMIC MODEL A-A' 24 FIGURES 25 FIGURE 1.VICINITY MAP 25 FIGURE 2.SITE PLAN 26 FIGURE 3. EROSION CONTROL NOTES 27 AAG23-082 8947 Buttonwood Lane NE, Olympia, WA 98516 5 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL INTRODUCTION This report summarizes the results of our geotechnical consulting services for the proposed expansion of an existing residence on the parcel herein described. The residence will extend living area to the southwest of the existing structure. This is in the northeastern part of the parcel which is a 1.42-acre quadrilateral somewhat long to the east-west. The longest leg is parallel to State Route 300. In general, the property slopes in low terraces gently to Mission Creek to the west. There is the beginning of a steeper ascending hillslope on the east side of the parcel that rises off parcel. This overlooks the proposed development and requires a geotechnical report. The property is approximately 2.5 direct miles southwest of Belfair and not much further by road. The location of the site is shown relative to the surrounding area on the Vicinity Map,Figure 1. Our understanding of the project is based on our discussions with the client. In general, there will be little grading needed to develop the building site as it is effectively flat. The new structure will be built a few feet up to match the elevation of the current residence, likely with stem walls. Figure 2 in the Appendix shows the location of the proposed expansion in the general context of the topography and parcel boundaries. It overlies LiDAR which shows the bare-earth features on-site. Access is directly off State Route 300. The purpose of our services is to evaluate the surface and subsurface conditions at the site in order to satisfy the requirements of the Mason County Critical Areas Ordinance. Specifically, our scope of services for this project includes the following: 1. A review of the available geologic,hydrogeological and geotechnical data for the site area. 2. A 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. Initial observations indicated the slope on the east exceeding 40% and is greater in height than 10 feet. This is considered a Landslide Hazard Area(LHA) Therefore, Mason County requires that a geotechnical report be prepared in accordance with the Mason County Resource Ordinance Sections 8.52.140. 1) SITE CONDITIONS SURFACE CONDITIONS The proposed location for the new residence expansion is located in the northeastern part of the parcel. The site is a series of flat terraces a few feet high descending west to Mission Creek. The current residence is on the uppermost terrace at an elevation of 30 feet above msl. The expansion will be built at an elevation of approximately 27 feet and will have stem walls raising the useful residential space to that of the current AAG23-082 8947 Buttonwood Lane NE,Olympia, WA 98516 6 Phone#: (360)491-5155 Cell #: (360)481-6677 ALL AMERICAN GEOTECHNICAL residence. There will be open exposure on all sides except to the east due to the steep hill noted above. The LHA to the east has an even rise of perhaps 25 feet at its maximum. The overall site elevation is from below 20 feet at Mission Creek to just under 50 feet on the slope at the east property line. AS noted, development will be on or just below the 30-foot contour. Curtis D Cushman, L.E.G. and Blaise Jelinek E.I.T., conducted a site reconnaissance on July 25, 2023. The purpose of a site visit is to physically observe the property and adjacent properties in order to identify any recognized geologic conditions. Subsurface exploration was done by observing exposed soil across the site and in inspecting the LHA slope area. Visual observations were documented. Site-specific features were mapped. The parcel has substantial second-growth trees including firs mainly around the Mission Creek area. He current ground cover is grass in the proposed building area and, despite a canopy formed by individual trees, the parcel is quite open at ground level. There are no trees over the current residence, and minimal tree removal, if any would, be needed for developing thee expansion. No evidence of deep-seated slope instability was observed onsite. There was no evidence of small-scale landslides on the LHA itself. The slope was cut-back at some time to make room for the current residence. A) SITE GEOLOGY The building site area as well as the entire parcel is mapped as follows on the Washington Geologic Information Portal Geologic Unit Symbol: Qa Geologic Unit Age: Holocene and late Pleistocene Geologic Unit Name: Alluvium Associated Unit: Qoa Publication Source: WGS Publication Number: OFR 2009-7 Quadrangle Name: Belfair Feature Link: WGS I OFR 2009-7 1 Belfair I Qa Unit Description: Silt, sand, and gravel; clasts typically well rounded; typically well sorted and loose; stratified to massively bedded; deposited in streams and adjacent banks. The sediment source is most commonly reworked recessional outwash, ablation till, advance outwash, and(or)glaciolacustrine deposits, but may include lodgment till, nonglacial deposits, and bedrock... Age: Quaternary Lithology: alluvium Age-Lithology: Quaternary alluvium The Geologic Map of the Belfair 7.5-minute Quadrangle, Mason, Kitsap, and Pierce Counties, Washington; Polenz, Michael, and others; DNR OFR 2009-7 strongly indicates (although the scaling cannot be precise)that the deposits on the parcel are Qgic,described on the Information portal as: AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 7 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL 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...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 geology does not preclude development. The low terraces are likely ice-contact deposits and sculpted post-glacial floodwaters, and/or they involve human development of some sort. One flat area was anecdotally said to have had a home on it. The parcel has a Shoreline Environmental Designation of a "Stable slope." DNR 2010 shows no near landslide. The DNR 2007 Hazard Zone is "Severe." The DNR 2009 Landforms is"Low." The National Wetlands Inventory shows a small wetland over 600 feet to the southeast at the mouth of Mission Creek. Shoreline Environmental Designation is "Residential." The samples appear in the field to be SP — Poorly-graded gravelly sand. (ASTM classification). This varies and can be a different designation in this environment. Increased gravel is possible. A water well on nearby Gladwin Road has a driller's log of dominantly sand and gravel The deposits are compact when probed. The building area is stable and suitable for construction. There are no nearby mapped faults and the nearest active fault zone is the Tacoma Fault extending east and west of Allyn,Washington,to the southeast north. Seismic acceleration is important in modelling the slope stability as the Puget Sound area is in an active tectonic zone. This fault system is part of the Tacoma Fault and a Tacoma Fault Seismic Scenario has an MMI of 8, or "Severe." The Seattle and Cascadia Seismic Scenarios are also at MMI 8. Low levels of seismic activity are not uncommon. AAG23-082 8947 Buttonwood Lane NE,Olympia, WA 98516 8 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL B) SOIL TYPES The soils are described by the USDA Web Soil Survey as: Ed—Everett gravelly loamy sand,0 to 5 percent slopes Map Unit Setting • National map unit symbol:2hk6 • 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 • Farmland classification: Prime farmland if irrigated Description of Everett Setting • Landform: Terraces • Parent material.Glacial outwash Typical profile • HI -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:0 to 5 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 in'hr) • Depth to water table:More than 80 inches • Frequency offlooding:None • Frequency of ponding:None • Available water supply, 0 to 60 inches:Very low(about 2.5 inches) The description of the Everett soil is in keeping with what is seen across the property both at the development site and at the LHA slopes. Source may be the ice-contact deposits. The soil is shallow and development will remove it to the underlying glacial deposits. The soils elsewhere on the property and off-property will not be disturbed. The soil is important where disturbed in that erosion on denuded slopes must be avoided. AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 9 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL C) GROUNDWATER CONDITIONS There was no evidence of active surface erosion on site. Mission Creek is a good-sized flowing stream whose main channel is approximately 100 feet from the development site and is in a channel off-parcel to the west. Shallow development should not encounter the water table. D) UPSLOPE GEOMORPHOLOGY The hill on the east is an erosional feature that likely dates back to the outwash of the melting glaciers scouring out the Mission Creek basin. It rises about 35 feet above the development area where is flattens out and continues to rese gently to the northeast. Slope stability models in this report show it is not likely to fail, with high Factors of Safety. The upslope overall poses no geotechnical hazard to the property. E) UPSLOPE WATERBODIES AND WETLANDS There are none. F) LANDSLIDE ACTIVITY The Belfair 7.5-minute quadrangle shows scattered landslide activity. The closest to the client parcel are two small ones approximately 1,000 feet to the north, on the left bank of Mission Creek. One appears, using LiDAR,to be due to stream undercutting while one to the north appears to have been due to a possible oversteepened slope. There next landslides mapped re in Little Mission Creek. LiDAR from the Mason County GIS shows no nearby landslides or landslide deposits. (See LiDAR Image in Appendix.) There was no evidence of current on-site landslide activity. 2) SITE PLAN The proposed residence expansion is located on Figure 2. The geology and soil are as noted. 3) EXPLORATORY HOLES OR PROBES The site was surface examined especially at the sample locations mapped on Figure 2. Exposures are readily seen especially on the banks o Mission Creek. AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 10 Phone#: (360)491-5155 Cell #:(360)481-6677 ALL AMERICAN GEOTECHNICAL 4) PROPOSED DEVELOPMENT Figure 2 shows the required features of the proposed development, the boundaries of the hazard area (LHA), and associated buffers and setbacks. The structure will be only partially within the 50-foot vegetation buffer, and this area is in grass for the most part. 5) CROSS SECTION Two(2)cross-sections are in the Appendix. They are along line A-A' which crosses the steepest slope and intersects the existing residence and the proposed addition. 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.S, the minimum seismic[dynamicj safety factor is 1.1 and the quasi-static analysis coefficients should be a value of 0.1 S. Slope stability was modeled using the GALENA 6.1 program in both static and dynamic conditions (ca= 0.150 per Mason County code above). "Static" condition refers to an "as is" state of a given slope. "Dynamic"puts seismic acceleration into the model for earthquake conditions. Modeling density is 109-1bs per cubic foot, common for the outwash deposits. In its relatively lightly consolidated condition, cohesion of 200 lbs per square foot and phi angle of 34 degrees were selected as conservative values for Qgo in the model. The surface soil was field classified as a SP Poorly graded silty sand with gravel. These units are consistent with the description of the Qa/Qgic deposits. The site was modeled as 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 Qa-Quaternary Alluvium 109 200 34 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=0.150),the computations demonstrated that the site has an acceptable FoS with respect to the streamside slopes (Line AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 11 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL A—A'). 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. Table 2. Initial Positions,Variance, and Findings Analysis Load Across JAnalysis JEarthquake Slope to Initial Positions Analysis R!nLeJJContigurationsJFactor of Number Building Envelope IType I Force Building ILower JUpper JRadius JAnalyzed ISafet,, Cross-Section A_a' Anal OOu 87-174' Static 1 0.0 g JAbove 1 130 88 230 65 150 80 125,001 12.83 Analysis 2 11500#87-174' IDynamic 1 0.15 g JAbove 1 130 88 230 65 150 80 125,001 11.93 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 23-24. Note FoS dynamic above 1.1 and static above 1.5. Landslides are unlikely under these conditions. 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 very dense 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 65 percent of gravity (g). We recommend following seismic factors for design purposes. • Site Class: D (stiff soil) • Spectral response acceleration, short period (SMs): 1.635g (Fa= 1.0) • Spectral response acceleration, 1-second period(Smi): null (F,=null) • Peak Ground Acceleration(PGA) 0.699 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 AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 12 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL between the concrete and the underlying native soil. We recommend the following be used to determine the lateral earth pressures considering the onsite SP: • 0 (soil friction angle) 34 degrees • Ko (at rest earth pressure coefficient) 0.441 • Ka(active earth pressure coefficient) 0.283 • Kp (passive earth pressure coefficient) 3.54 • y(soil unit weight) 109-pcf 7) RESTRICTIONS A) PLACEMENT OF DRAINAGE FEATURES Drainage should be done by capturing water and using overland flow to disperse it on the surface. An alternative is having it transported by a drainage tightline to an allowed drainage feature, such as the Mission Creek former channel on-parcel. All ground surfaces,pavements and sidewalks should be sloped away from the proposed residence and any 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 soil is relatively permeable and surface dispersal is recommended. Figure 3 also shows recommendations for the tightline system that may be applicable to this parcel. B) PLACEMENT OF SEPTIC DRAIN FIELDS The drain fields are pre-exiting. Please refer to Figure 2. C) PLACEMENT OF COMPACTED FILLS AND FOOTINGS RECOMMENDATIONS FOR SITE PREPARATION The area proposed for construction is in lawn and suitable for construction. The building footprint for possible construction is partially inside the 50-foot vegetation buffer. Construction may proceed if standard practices of erosion control are followed as surface vegetation is cleared. All areas to be excavated should 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. AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 13 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL If demonstrated to be acceptable,the gravelly sand sedimentary material on site may be suitable for use as structural fill. Any encountered silts or clays may not be used 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 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. The on-site material may be suitable for structural fill. D) BUFFERS The location for the residential expansion is partially inside a 50-foot buffer associated with the LHA. As the site is well developed as a residential lot, this will not be conducive to erosion. In addition, there is adequate setback so the LHA is not hazardous to the expansion. E) SETBACKS The building location is outside of an h/2 runout which would be 20 feet at the most. AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 14 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL 8) CLEARING AND GRADING PLAN No timber clearing will be needed. Individual trees may have to be felled, but they will be limited in number if any.No grading is anticipated except maybe to develop the foundation. "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. 9) EROSION CONTROL PLAN It is our opinion that the potential erosion hazard of the site is not a limiting factor for the proposed developments. The vegetation is lawn grass on flat natural/developed platforms. Revegetation as needed should occur immediately following construction. The possibility of down-slope contamination is highly unlikely if proper control methods are employed. A silt fence may be installed as shown on Figure 3. No re-contouring of the site will occur. 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. 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. 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 bluff should be left in a natural condition unless erosion or sloughing eventually pose a hazard to the property. 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 expanded residence. 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 none. AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 15 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL 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 site is suitable for the proposed project. Revegetation, as needed, should be done immediately following completion of work. Erosion control should involve a silty fence and straw bales should be available in case of emergency or to spread straw on denuded areas. A following CMZ report will detail flood hazards. PROVISIONS GENERAL We have prepared this report for the exclusive use of Laura and Matthew Harkins and their authorized agents for the proposed development 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 Critical Areas 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. AAG23-082 8947 Buttonwood Lane NE,Olympia, WA 98516 16 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL 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. 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. The equipment,techniques and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study and vice versa. For that reason, geotechnical engineering or geologic reporting does not usually relate any environmental findings, conclusions or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding a specific project. AAG23-082 8947 Buttonwood Lane NE,Olympia, WA 98516 17 Phone#:(360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL REFERENCES MAPS DeLorme 3-13 TopoQuads(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. 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 suspectedfaults with quaternary displacement in the Pacific Northwest,published by U.S.Geological Survey OFR 91-441-0,Plate 1,scale 1:2,000,000. Washington State Department of Ecology(1979),Coastal Zone Atlas of Washington, Volume 9,published by Washington State Department of Ecology. PUBLICATIONS ASTM International, Annual Book of Standards 2020, 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. International Code Council,Inc.(2020),2020 International Building Code,published by International Code Council,Inc. 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 USDA 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(ON LINE AS USDA WSS,MASON COUNTY GIS,D OF ECOL WATER WELLS AND COASTAL ZONE ATLAS,AND THE WASHINGTON GEOLOGIC INFORMATION PORTAL AND DNR MAPS,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.httnl) Slope Stabilization Erosion Control Using Vegetation A Manual of Practice for Coastal Bluff (http://www.ecy.wa.gov/biblio/9330.html) AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 18 Phone#: (360)491-5155 Cell#:(360)481-6677 ALL AMERICAN GEOTECHNICAL 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 (http://soildatamart.nres.usda.gov) Washington Administrative Code (http://apps.leg.wa.gov/wac/) Washington Department of Ecology (http://apps.ecy.wa.gov/welllog) (https:Hfortress.wa.gov/ecy/coastalatlas/viewer.htm) AAG23-082 8947 Buttonwood Lane NE,Olympia, WA 98516 19 Phone#:(360)491-5155 Cell #: (360)481-6677 ALL AMERICAN GEOTECHNICAL APPENDIX ASCE7-16 Seismic Design Specifications Neighboring Well Log Slope Models Figure 1.Vicinity Map Figure 2. Site Plan Figure 3 Erosion Control Notes AAG23-082 8947 Buttonwood Lane NE,Olympia, WA 98516 20 Phone#:(360)491-5155 Cell #:(360)481-6677 ALL AMERICAN GEOTECHNICAL ASCE7-16 SEISMIC DESIGN SPECIFICATIONS OTC Hazards by Location z t Search Information Coordinates: 47.432,-122,875 Cua'sPainting9 Q se n a40 ` 8 F.D.4X4 Elevation: 26 1", Gdadwin Beach House© E� Timestamp: 2023-08-08T18 48..56.884Z Chnstelrn nee Cabin _ NE Beck RC� � d Hazard Type: Seismic c;odr,� Reference Document: ASCE7-16 s North Shore Self Storage ,,1 Risk Category: III GOr]gICZ,,,,'- Map data 02023 Google rtepw a map erta Site Class: D Basic Parameters Name Value Description S; 1 F'35 MCER ground motion(period=02s) St 0.564 MCER ground motion(period=l-Os) SMs 1 635 Site-modified spectral acceleration value SMi 'null Site—modified spectral acceleration value SDS 1.09 Numeric seismic design value at 0.2s SA SDt 'null Numeric seismic design value at 1 Ds SA See Section 11.4 8 -Additional Information Name Value Description SDC nu.I Seismic design category Fa 1 Site amplification factor at 02s Fv 'null Site amplification factor at 1.Os CRS 0.903 Coefficient of ask(029) CRi 0.883 Coefficient of risk(I Ds) PGA 0.699 MCER peak ground acceleration FpG 1.1 Site amplification factor at PGA PGAM 0.769 Site modified peak ground acceleration TL 16 Long-period transition period Its) SsRT 1.635 Probabilistic risk-targeted ground motion(02s) SsUH 1.812 Factored uniform-hazard spectral acceleration(2%probabAity of exceedance in 50 years) SsD 3.597 Factored determnistc acceleration value(0.2s) SiRT 0.584 Probabilistic risk-targeted ground motion i1.0s) S1 UH 0.662 Factored uniform hazard spectral acceleration(2%probability of exceedance in 50 years) S1D 1244 Factored deterministic acceleration value It Os) PGAd 1.17 Factored deterministic acceleration value(PGA) See Section 11.4 8 AAG23-082 8947 Buttonwood Lane NE,Olympia,WA 98516 21 Phone #: (360)491-5155 Cell #:(360)481-6677 ALL AMERICAN GEOTECHNICAL NEIGHBORING WELL W A I I R V I L L R E P 0 R I Start Card No. VISS140 Unique Nell 1.0. 1 ACA214 STATE Of WASHINGTON Nater Rignt Permit No. z'.&. Z.-tZI...Z Z 2 7 Z Z;1 2 Z Z 2 Z::;I;=:::%Z Z T 1 t ft Z%T Z r t T t 1 Z Z (11 OWNER: mate STINGER, ROY A NADINE Address 4119 6071 AVE W TACOMA, VA 91466-6311 (2) LOCATION Of NELL: Count MASON SW 1 4 SE 1/4 Sec 36 1 23 1.. R 20 Wx ua) s m u Anuss or #Ett �or nearest address) ME SalGLADWIN All. ULFAU (f) PROPOSED USE: DOMESTIC = (101 WILL LOG ................................................................ (4) TYPE 01 WORK: Owner's Number of Well Formation; Describe by color, character, size of material fit more than one) I and structure, and show thiclAess of aquifers and the kind MEN WELL Method: NOTARY and nature of the material in each stratus penetrated, with at least one entry for each change in formation. (5) DIMENSIONS: Diameter of well 6 inches -------------------------------------- ------- ------------------ Orillpd S6 It. Depth of completed well 51 ft. f MATERIAL FROM TO ............. PIPE STICK-UP 16) CONSIRUCTION CITARS: flit 3 12 Casing installed: 6 Dia. Eros #1 It. to S6 ft. I BROWN SAND GRAVEL SOME CLAY WELDED Dia. from ft. to ft. BROWN SAND SOME GRAVEL RUDDY WATER 12 45 Dia. from ft. to It. BANN SAID GRAVEL I WATER 45 1 S6 .......................................................... Perforations! 00 Type of perforator used SNE of perforations in. 11 perforations from It. to perforations from ft, to ft. perforations from It. to It. ......................................... ................ Screens: YES manufacturer*s Name l I t Type STAINLESS model go. TELESCOPING I Dias. 6 slot "17P 20 from SO it. to S6 ft. Dias. slot size trod it. to it. --------------*------------- --- -------------------------Gravel parked: NO Sire of gravel Gravel placed from ft. to It. ir ----­------*'-"--" ­--------*------*------------------Surface spat: YES To what depth? 18 ft. Material used in seal KITOMITE 1 E:. Did any strata contain unusable water? 10 Type of water? Depth of strata It. method of sealing strata off .........­­............... ......... ...... 111 PUMP: hanufacl!irer's Dame Type H.P. ........... ......... (9) MAHR LEVEL',; Land-Surface elevation .. above mean sea level ... ft. Static lt.,el 6 It. below top of well Date 47113191 Artesian Pressure lbs. per square inch Cate Artesian water rontrolled by Wort started 01123i9l completed 01)23197 (ql Vl,,j !fSjSj 8raw4own is Amount water level is lowered below WELL CONSTRUCTOR CEVINCATION: Static level. I I constructed and/or accept responsibility for can- Was a pump test made' 00 11 yes, by who? structiop of this well, and its compliance With all Yield: jal.1min with ft. drawdown after firs. f Washington well construction standards. Materials used and the information reported above are true to my best knowledge and belief. Recovery data Time water tev?i Time Water Level Time Water Level NAME NICHOLSON DRILLING INC I I (Person, firm, or corporation) (Type or print) I ADDRESS 12 Date of le,-t Nile( test 20 0 in. 18 it. dr;WODWA after I firs. I [SIGN License No. IS19 Air test tat in. w/ stes set at ft. for firs., Artesian flow 9-9-1. Date ; Con for's temperature %I water Ida-, a chemical analysis made? NO , Registration N ]SION Date 081.3191 AAG23-082 8947 Buttonwood Lane NE, Olympia, WA 98516 22 Phone#: (360)491-5155 Cell #: (360) 481-6677 ALL AMERI C AN G E O TE C HNI CAL SLOPE MODELS STATIC MODEL w-' E00 \ ( / \2 } F k ; Q ] \ k } ka \ / ia I3 _ k � \ , j ) @ � i \� , ¥ 05 \\ k ! 7 ` � a q k ¥ 2 \ \ 9 ) ° ID - ~ ° % ] « § ` ^ /7 } - %%G2 yOS2 8947 Buttonwood Lane NE, Olympia., W& 98516 23 Phone e %6q 4 G5155 Cell ¢ b 6g 48 1-6677 ALL AMERICAN GEOTECHNICAL DYNAMIC MODEL A-A' o, ci a, c T!c YF N C V Q C c n h 0 V O Q N �- Y L a � M :� a u 4 a 0 `\ N R E 0 8 1 I 1 I g ,I I I I I � rn I a ` I m i 5 iF � N � s c i ^J Jy � W � Q � o J = 'E I g 8 C) CD m A AAG23-082 8947 Buttonwood Lane NE,Olympia, WA 98516 24 Phone#: (360)491-5155 Cell#: (360)481-6677 r A +• AA /��j �� Mo f 7 t NOTES of Wash.. This is not a survey. This map presentation of infofioff,M from - ' J county, state, and/or federal <►re�„�cco,�,,sr �� E d 2439 agencies, client provided - 7 GPo °- 70'- information and onsite ��an, o o, �� r]P--� '�.1!,: observations. 232- ; I E e Sample 0--We1,l ( is ng) Site Soils Key �. o Exis g Ed Everett gravelly loamy sand, 0 to 5 percent slope �° ���° <` Sajnpe 60 Ee Everett gravelly loamy sand, P 5 to 15 percent sloe p Ic Indianola loamy sand, • ample tiv e ay 15 to 30 percent slope 20 Site Geology • Qa -- Quaternary alluvial I = SC&ALE,.: AR deposits `''' AV Z i All American Geotechnical, Inc. Project Drawn By: Site Plan Figure Permit Number: Parcel '�umber --„7--01--`1-)1001 8947 Buttonwood Lane NE Number: BWJ 8/8/23 Proposed Addition 2 Olympia, Washington 98516 AAG22-082 Belfair, WA Laura& Matthew Harkins Applicant Name: Site Address: 3040 NE State Highway 300 Page 26 FILTER FABRIC MATERIAL 60'WIDE ROLLS USE STAPLES OR WIRE RING TO ATTACH FABRIC TO WIRE 2'X2'X14 GAUGE WIRE FABRIC OR EQUIVALENT Fl GENERAL EROSION CONTROL NOTES: Z-0" : : . . 1. EROSION CONTROL MEASURES SHALL BE IN PLACE PRIOR TO THE BEGINNING OF CONSTRUCTION. THE PROJECT ENGINEER AND THE COUNTY 5'-0" . . 7777 T MUND SURFACE SHALL INSPECT AND APPROVE THE INSTALLATION OF 1/2 INCH MINIMUM DIAMETER STEEL ROD EROSION CONTROL MEASURES PRIOR TO BEGINNING CONSTRUCTION. (STRAP)CLAMPED SECURELY TO PIPE 2•-0• •.-;-;-..__.•......•............ ,- 2. EROSION CONTROL MEASURES ARE NOT LIMITED TO THE ITEMS 6'MAX ON THIS PLAN. THE CONTRACTOR IS RESPONSIBLE FOR THE CORRUGATED TIGHTLINE 4 INCH INSTALLATION AND MAINTAINANCE OF ALL EROSION CONTROL MEASURES. MINIMUM,6 INCH SUGGESTED NO SILTATION OF EXISTING OR PROPOSED DRAINAGE FACILITIES ('�R 4fz SHALL BE ALLOWED. CARE SHALL BE TAKEN TO PREVENT MIGRATION �=="-` 2"X4"WOOD POSTS,STANDARD OR BURY BOTTOM OF FILTER OF SILTS TO OFF SITE PROPERTIES. ?' �." •'•• S' M 7 BETTER OR EQUAL ALTERNATE: MATERIAL IN 8"X12'TRENCH r" - ':F '' p C OFF STEEL FENCE POSTS 3. THE CONTRACTOR SHALL MAKE DAILY SURVEILLANCE OF ALL EROSION .: .:�<>< G CONTROL MEASURES AND MAKE ANY NECESSARY REPAIRS OR ADDITIONS ;;..�:;�..:." •�,:t;::.:;:.;''.,., c�„ TO THE EROSION CONTROL MEASURES. THE CONTRACTOR SHALL PROVIDE ADDITIONAL EROSION CONTROL MEASURES AS DETERMINED NECESSARY BY THE COUNTY INSPECTOR AND/OR THE PROJECT ENGINEER. FAILURE FILTER FABRIC 6" TO COMPLY WITH ALL LOCAL AND STATE EROSION CONTROL "' c-?•:.'.?;':. +:'.`"_^,< "'.0 er.'. ' 2"X2"X14 GAUGE WIRE REQUIREMENTS MAY RESULT IN CIVIL PENALTIES BEING LEVIED t`�'- •.•:-a,:,�<'.> '�'_'"'•'•'�'n�:•.� -+r,•'�',::`. AGAINST THE CONTRACTOR AND/OR PROJECT OWNER. FABRIC OR EQUIVALENT -4.:';' S.�-:^�•�:� ;:�' 2•-0. ,j%•'+vim•-�:;•Y;..=_,� :.,,'z.;:'+.J.n:y�°i.` -•S�...••-.`:..vz.�:•-`I' GROUND SURFACE 5'-0" 4. DURING THE WET SEASON(NOVEMBER TO MARCH)ALL DISTURBED SOILS �•;:.�:�,.: < _.';,;.;�;:;;�:.: ,. y1�`y yam: SHALL BE STABILIZED WITHIN 48 HOURS AFTER STOP OF WORK. EROSION ='�' `�=''.' ~•"' •' `•`'`=tea%xa°:: 'r=!:`'' CONTROL MEASURES SHALL INCLUDE,BUT NOT BE LIMITED TO, PROVIDE ACK 1/2"WASHED COVERING THE EFFECTED AREA INCLUDING SPOIL PILES WITH GRAVEL BACKFILL IN TRENCH 12^ ,��;..,�--!r;•�;;>;>.: �``�' AND ON BOTH SIDES OF FILTER PLASTIC SHEETING,STRAW MATTING,JUTE MATTING,STRAW MULCH, FENCE FABRIC ON THE SURFACE OR WOOD CHIPS. SEEDING OF THE DISTURBED AREAS SHALL TAKE WWI 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 REQUIRED. FILTER FABRIC FENCE NOTES: 1. FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO 6. TRACKING OF SOIL OFFSITE WILL NOT BE ALLOWED. IF ANY SOIL IS TRACKED ONTO A COUNTY STREET,IT SHALL BE REMOVED BY THE END THE LENGTH OF THE BARRIER TO AVOID USE OF JOINTS.WHEN JOINTS 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 6-INCH 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 MAXIMUM OF 6 FEET APART AND DRIVEN 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 8 INCHES WIDE AND 12 8. EXCAVATED MATERIAL SHALL BE PLACED ON THE UPHILL SIDE OF TRENCHES. /Gy FLARE END SECTION INCHES DEEP ALONG THE LINE OF POSTS AND UPSLOPE FROM THE BARRIER. 9. TRENCH DEWATERING DEVICES SHALL BE DISCHARGED IN A MANNER THAT WILL QUARRY ENERGY 4. WHEN STANDARD STRENGTH FILTER FABRIC IS USED,A WIRE MESH �A SP OR ENERGY _,:^�•' i '-` SUPPORT FENCE SHALL BE FASTENED SECURELY TO THE UPSLOPE SIDE NOT ADVERSELY AFFECT FLOWING STREAMS. DRAINAGE SYSTEMS OR ..�; _..1.;:^?��'„, ., ^:.:Y; OF THE POSTS USING HEAVY-DUTY WIRE STAPLES AT LEAST 1 INCH OFFSITE PROPERTIES. DISPERSION DEVICE + ? ;; „:,Y—:•'.14'•;; 'i_:ii �'a ' "' LONG,TIE WIRES OR HOG RINGS. THE WIRE SHALL EXTEND INTO THE TRENCH A MINIMUM OF 4 INCHES 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 GRASS-LINED SWALE SHOULD BE A WILL BE FILTERED BEFORE ENTERING THE CONVEYANCE SYSTEM. MINIMUM ONE FOOT WIDE AT THE 5. THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED TO THE FENCE AND 20INCHES OF FABRIC SHALL BE EXTENDED BOTTOM AND ONE FOOT DEEP WITH INTO THE TRENCH. THE FABRIC SHALL NOT EXTEND MORE THAN 36 11.ALL OFF-SITE 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 6. WHEN EXTRA-STRENGTH FILTER FABRIC AND CLOSER POST SPACING IS OF WORK. THE CONTRACTOR SHALL BE RESPONSIBLE TO ENSURE THAT LEVEL SECTION USED,THE WIRE MESH SUPPORT FENCE MAP BE ELIMINATED,IN SUCH COMPLETE COVERAGE OF THE DISTURBED AREAS IS PROVIDED&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. 13.CATCH BASINS SHALL TRAP SEDIMENT OR FILTER FABRIC MUST BE 7. FILTER FABRIC FENCES SHALL NOT BE REMOVED BEFORE THE UPSLOPE PLACED UNDER GRATE UNTIL VEGETATION IS ESTABLISHED. AREA HAS BEEN PERMANENTLY STABILIZED. 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. Drawn B Figure All American Geotechnical, Inc. BW J y Erosion Control Notes Permit Number: Parcel Number: 22201-51-91001 3 8947 Buttonwood Lane NE 8/8/23 Proposed Home Addition Olympia, Washington 98516 Applicant Laura&Matthew Harkins 3040 NE State Highway 300 Page � Revisions: Belfair, Washington pp 'cant Name: Site Address: g 27