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Home My WebLink AboutGEO2020-00076 Report and Addendum - GEO Geological Review - 8/6/2020 MASON COUNTY COMMUNITY SERVICES G@Ot@ChtllCal Report Building,Planning,Environmental Health,Community Health 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 International Residential Code Sections R403.1.7 for foundations on or adjacent to slopes, Section R403.1.8 for expansive soils or section 1808.7.1 of the International Building Code Section for Foundations on or adjacent to slopes. A licant/Owner V 1 G� C% -, PP ✓ �` 1 H �CParcel# h,C�3 ,2 y- GC.'.ac—, �} Site Address 1/ L? / 7D (1) (a) A discussion of general geologic conditions in the vicinity of the proposed development, Located on page(s) (b) A discussion of specific soil types,/ Located on page(s) (c) A discussion of ground water conditions, Located on page(s) (d) A discussion of the upslope geomorphology, Located on page(s) (e) A discussion of the location of upland waterbodies and wetlands, Located on page(s) S (f) A discussion of history of landslide activity in the vicinity, as available in the referenced maps and records. Located on page(s) (2) A site plan which identifies the important development and geologic features. Located on Map(s) J� (3) Locations and logs of exploratory holes or probes. Located on Map(s) (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) 5- (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) 6 (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) 6 (7) (a) Appropriate restrictions on placement of drainage features, Rev. February 2018 Located on page(s (b) Appropriate restrictions on placement of septic drain fields, Located on page(s) 6 (c) Appropriate restrictions on placement of compacted fills and footings, Located on page(s) b (d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes. Located on page(s) /V (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes. Located on page(s) 7 (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) 7 (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) 7 (10) An analysis of both on-site and off-site impacts of the proposed development. Located on page(s) 7 (11) Specifications of final development conditions such as, vegetative management, drainage, erosion control, and buffer widths. Located on page(s) 7 (12) Recommendations for the preparation of structural mitigation or details of other proposed mitigation. Located on page(s) '7 (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) �7 z— I, U q rK % i ereby 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 tig at W&S Geotechnical Report, dated 4, IiW 6 G'Z0, and entitled p_G O Zu L meets all the requirements of the Mason County Resource Ordinance, � Geologically Hazardous Areas Section, is complete and true, that the i f ^ew can assessment demonstrates conclusively that the risks posed by the iC 2439 ed Geoff �y s� p landslide hazard can be mitigated through the included geotechnical S design recommendations, and that all hazards are mitigated in such a Curtis Dean Cushman i manner as to prevent harm to property and public health and safety. gna ur Page 2 of 2 Disclaimer:Mason County does not certify the quality of the work done in this Geotechnical Report. ADDENDUM TO GEOTECHNICAL REPORT RESIDENTIAL DEVELOPMENT SITE EAST STATE ROUTE 106 UNION, WASHINGTON PREPARED FOR BRIAN STEFANKO BY ALL AMERICAN GEOTECHNICAL OLYMPIA, WASHINGTON AUGUST 6, 2020 ALLAMENCAN O i ECNIA ADDENDUM TO GEOTECHNICAL REPORT CONTACT INFORMATION PREPARER INFORMATION AAG PROJECT NUMBER: AAG20-063 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: BRIAN STEFANKO TELEPHONE: (360)633-9289 BILLING ADDRESS: BRIAN STEFANKO 4775 NE LAMMS LANE POULSBO,WA 98370 SITE ADDRESS: 11510 E STATE ROUTE 6 UNION,WASHINGTON EMAIL BRIANSTEFANKO@GMAIL.COM PARCEL NUMBER 22230-24-00000 GPS LOCATION: N470 22' 12" W1220 59' 13.2" (Inside parcel 22230-24-00000) AAG20-063 8947 Buttonwood Lane NE, Olympia, WA 98516 2 Phone#: (360)491-5155 Cell#:(360)481-6677 i I ALL AMERICAN GEOTECHNICAL ADDENDUM BRIAN STEFANKO 4775 NE LAMMS LANE POULSBO,WASHINGTON 98370 RE: GEOTECHNICAL REPORT PROPOSED RESIDENCE 11510 E STATE ROUTE 106 UNION,WASHINGTON N470 21' 12" W 122°05'59.13.2" PARCEL: 22230-24-00000 AUGUST 6,2020 Dear Mr. Stefanko: Brian Stefanko (client)hired All American Geotechnical, Inc. (AAG) in August 2018 to do a preliminary site evaluation for a residential property with outbuildings on one or more of three lots in Mason County, Washington. AAG provided a geotechnical report dated February 20, 2020 titled Residential Development Site East State Route 106 Union, Washington. The observation, information, conclusions and provisions of this report remain valid. Upon improved access onto the property, the client requested another potential building site be considered. To that end, we reviewed the earlier report, added the site to our Figure 2 now marked as Revised: 7127120. A cross-section, marked D—D', was drafted and two slope-stability analyses were run along this line. The results exceed the Factor of Safety standards for Mason County and are printed on the cross-sections. The revised Figure 2 and the cross-sections are in this addendum. 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. Respectfully Submitted, of washy ALL AMERICAN GEOTECHNICAL,INC. o� fjZ I �i� i9ineering Geobgist C 2439 �5~ Ssd Geo�o Curtis D. Cushman,L.G.,L.E.G. Senior Engineering Geologist Curtis Dean Cushman AAG20-063 8947 Buttonwood Lane NE,Olympia,WA 98516 3 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL Am cA G oT c icAL 1) SITE CONDITIONS SURFACE CONDITIONS The proposed location for rural residential development is located in Parcel 22230-24-0000 located approximately 400 feet south of the original site location(marked by cross sections A—A'and C— C') as seen on Figure 2. The area is presently undeveloped and heavily wooded. The residence is located outside the 50-foot buffer. A) SITE GEOLOGY The following is taken from the Mason Lake 7.5-minute Quadrangle, Mason County, Washington; by Derkey, et al.; 2009; DNR Open File Report 2009-06. The residence will be constructed on Pre-Vashon sediments(Qpu)described briefly as follows: Qpu -Pre-Vashon sediments, undifferentiated(Pleistocene)--Composite unit of glacial and nonglacial gravel, sand, silt, and clay beneath Vashon till; consists of sediment rich in northern provenance clasts; gray to tan; often iron-oxide stained; moderately to well rounded,poorly to moderately well bedded; consists of units that are not separable at map scale, due to poor exposure; may include some Vashon advance outwash; most commonly recognized in water wells in the quadrangle and depicted in cross sections... As a pre-Vashon deposit, this has been compacted by the Fraser ice-sheet and is suitable for construction in general. According to the CZAW map #MA_7ith.jpg, the site is almost entirely is in the Intermediate zone (I), with stable areas (S) above it. The CZAW maps shows no major (e.g. mapable) landsides in the immediate area. B) SOIL TYPES The soil in the areas of the proposed northwestern development is described by the USDA Web Soil Survey as: Ac—Alderwood gravelly sandy loam, 15 to 30 percent slopes At the building site,the soil would also be Ac Alderwood. This appears to be the soil that is seen in the road cuts and elsewhere on-site. The soil is not important to the placement of the residence as it is relatively thin and likely to be removed in developing the footings. AAG20-063 8947 Buttonwood Lane NE, Olympia, WA 98516 4 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOT NI AL C) GROUND WATER CONDITIONS The ravine to the east commonly has flowing water. There was no evidence of active surface in the area. D) UPSLOPE GEOMORPHOLOGY The slope continues up to the south to a ridge following the glacial scour trend of northeast-southwest approximately 600 feet to the south of the property line. This does not constitute an immediate geotechnical hazard to the parcel. E) UPSLOPE WATERBODIES AND WETLANDS There are none. F) LANDSLIDE ACTIVITY The 7.5-minute quadrangle shows a few small landslides in the stream to the east. This is an ongoing process due to over-steepened conditions in the valley walls. A large landslide on the Canal is located a half mile to the west, but this is shown in the cross-section as very thin as it is not differentiated from the underlying units. The adjacent mapping on the Union Quadrangle has these as mass-wasting deposits and not landslides, and they do not appear to be of concern for the client property. LiDAR from the Mason County GIS derived from the Puget Sound Lidar Consortium (g47122c81) shows no evidence of any landslides in the area around the site. In addition, the mapped landslides do appear to be shallow mass-wasting events and not deep-seated. There was no evidence of current on-site landslide activity. 2) SITE PLAN Please see Figure 2 in the appendix. 3) EXPLORATORY HOLES OR PROBES The site was surface examined along the access road, in exposures on the property, and as sampled as located on Figures 2. 4) PROPOSED DEVELOPMENT This will be a residence site. AAG20-063 8947 Buttonwood Lane NE,Olympia, WA 98516 5 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL ECAN OTECICAL 5) CROSS SECTION A cross section along line D-D' intersects the potential building site. 6) SLOPE STABILTY ANALYSIS The Slope Stability Analysis follows the Mason County Resource Ordinance of 2009 and is on the cross sections pages 11-12. All other data and results in this section are as per the original report. 7) RESTRICTIONS A) PLACEMENT OF DRAINAGE FEATURES All ground surfaces, pavements and sidewalks should be sloped away from the residence and associated structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and/or catch basins and tight lined into the appropriate drainage facilities. We recommend that conventional roof drains be installed. Footing drains shall be installed for the proposed structure. The roof drain should not be connected to the footing drain. For footing drains, the drain invert should be below the bottom of the footing. Typical drainage control measures are included on Figure 3 in the original report. The soil will accept downspout and other drainage located at least 5 feet from the edge of the footing of the residence. Figure 3 shows recommendations for a tightline system which is not likely a better option for this property. Drainage should be such that there is no flow onto the steep slopes to the east at the northwestern site. B) PLACEMENT OF SEPTIC DRAIN FIELDS The drain field is located as mapped on Figure 2. The drainfields will be well outside the LHA and buffer. Domestic water is from a well whose proposed location is mapped on Figure 2. C) PLACEMENT OF COMPACTED FILLS AND FOOTINGS RECOMMENDATIONS FOR SITE PREPARATION As per original report. D) BUFFERS Residence and septic lie outside the 50-foot buffer. The buffer is shown on Figure 2 by the marking of the buffer line. AAG20-063 8947 Buttonwood Lane NE, Olympia,WA 98516 6 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL A ERICAN " EOTEC ICA E) SETBACKS The site is outside of the acceptable hazards as defined by the slope stability model and the resultant Factors of Safety. The geotechnical setback is seen by the 200'well diameter on Figure 2. 8) CLEARING AND GRADING PLAN Timber clearing will be needed. No grading is anticipated except to develop flat building sites and create an acceptable entry road. "No Disturb" zones will not be required. No formal plan should be needed as long as safe procedures are employed with the clearing in keeping with Mason County regulations. All job site safety issues and precautions are the responsibility of the contractor providing services and/or work. 9) EROSION CONTROL PLAN It is our opinion that the potential erosion hazard of the sites is not a limiting factor for the proposed developments. There will be no development inside the 50-foot buffer. Please see original report for further comments and recommendations 10) ON AND OFFSITE IMPACTS There should be no notable on- or offsite impacts if the project is completed according to the recommendations of this report and in accordance with all regulations and to the high standards and practices of the building contractor. No geotechnical impact is anticipated in the construction of the residence. 11) FINAL DEVELOPMENT CONDITIONS All final conditions will follow the design by the Engineer of Record and compliance with all regulatory agencies. If this and the above recommendations are followed, final development conditions will be achieved. 12) STRUCTURAL MITIGATION There is no structural remediation to be done. 13) SITE PLAN Please see Figure 2. CONCLUSIONS AND RECOMMENDATIONS Based on the results of the site reconnaissance, subsurface observations, and our experience in the area, it is our opinion that the proposed site is suitable for the proposed improvements. As located, the proposed structure would not undermine adjacent slopes. AAG20-063 8947 Buttonwood Lane NE,Olympia, WA 98516 7 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AAN OTcNICAL PROVISIONS GENERAL We have prepared this addendum for the exclusive use of Brian Stefanko and his authorized agents for the proposed improvements in Mason County, Washington. Site inspections,research, and mapping have culminated in this report. This report is intended to meet the requirements of the Mason County Resource Ordinance. This report does not specify setbacks for: line-of-sight setbacks, FWHCA setbacks, eagle tree setbacks, wetland setbacks, or property line setbacks. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. No warranty or other conditions, expressed or implied, should be understood. Clients and property owners must understand that, while a slope may be found to have an acceptable Factor of Safety related to deep-seated mass wasting, surficial failure and landslides can and do occur on steep slopes. The property owners should monitor the stability of their property following construction. Moreover, acceptable Factors of Safety do not guarantee there cannot be failures. It is the responsibility of the property owners to understand that there are always risks in building on or near steeply sloped areas. 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. APPENDIX USGS Seismic Design Specifications Slope Models Figure 1. Vicinity Map Figure 2. Site Plan AAG20-063 8947 Buttonwood Lane NE,Olympia, WA 98516 8 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AM RICAN GEOTECHNICAL 2015 AASHTO DESIGN SPECIFICATIONS Search Information Pedmond Seattle ° Address: 47,371. o 116 ft Coordinates: 47,371.-122,988 olyrnt';: gam; National Forest Elevation: 116 it Kent Timestamp: 2020-01-21T01:13:09.762Z Tacoma Ito oPulallup Hazard Type: Seismic Reference IBC-2015 r.GO !c 01y'npla Document: t ° Map Report A map error Risk Category: III Site Class: D MCER Horizontal Response Spectrum Design Horizontal Response Spectrum Sa(g) Sa(g) 1.40 1.20 0.80 1.00 0.80 0'� 0.60 0.40 0.40 0.20 0.20 0.00 0.00 0 5 10 15 Period(s) 0 5 10 15 Period(a) Basic Parameters Name Value Description SS 1.42 MCEp ground motion(period=0.2s) Si 0.584 MCER ground motion(period=1.0s) SMS 1.42 Site-modified spectral acceleration value Spry 0.876 Site-modified spectral acceleration value SDS 0.947 Numeric seismic design value at 0.2s SA So, 0.584 Numeric seismic design value at 1.0s SA Additional Information Name Value Description SDC D Seismic design category Fa 1 Site amplification factor at 0.2s Fv 1.5 Site amplification factor at 1.0s CRS 0.981 Coefficient of risk(0.2s) CR/ 0.934 Coefficient of risk(1.0s) PGA 0.596 MCEG peak ground acceleration AAG20-063 8947 Buttonwood Lane NE, Olympia, WA 98516 9 Phone#: (360)491-5155 Cell#: (360)481-6677 Material Kevs y N O 450 Pleisbcene cial&wn4arw •• oc400a:36g:12i f� w C 400 � t" C 350 d 300 CD - ! 250 w � o 150 O 100 a Analysis I el 00 Multiple Stability Analysis ' a, Method: Bishop Simoified z Surface: Circular 000 -50 IM Results -1 00 6,1 Critical Factor of Safety: 2.39 . 0 100 200 300 400 500 600 GALENA vorft&ro r-Md"27 M 202o .• 27 dd 2IM Proi gt Brian Stefanko House Arialy�S Static D-D'Line File: Al American&Otechrucer Wem FW Sletadw St*D.gml All American GeOtechnical,Inc. o M - -_— -- - ---_--_ Material Keys ---------- ------�--- --r ,OO e36eg.t 2r&ron glacial , � 450 — , O 400 C t� r 0.298 to 350 C w ,�o � 250 0 0 s 150 4 I-< 100 50 a Analysis 1 o Multiple Stability Analysis 0 Method: Bishop Simplified Surface: Circular , Results Logo -100 Critical Factor of Safety: 1.21 0 100 200 300 400 500 600 GALENA vw=vo :27 but 2M Processed: 27 Jut 2020 P ect Brian Stefanko House Analysis 8 Dynamic D-D'Line ae C:VAB American GeotecWcaWdena RW Stela*Dynamic D.gm► [—All American Geotechnical,Inc. ALL ACA OC1\ICAL FIGURE 1 VICINITY MAP GUC'Y+ 123°00.000'W 122*59.000'W WGS84 122°58.000'W Of » v E3•y S.b 6sk cv a 24 am 0 J l `r ShW9 BNM ti 6 71-C,•ztl rian Stefaiiko r ; " 11510 Eas State Rout o Parcels: 22 Wo R ! 1 nhduz�� l y � / fir•/ r�� C � Y lJ � �' z / •,( z Fq a /I vv-rJJ 1 7 123101.000'W 123°00.000'W 122059.000'W WGS84 1220S8.000'W 4116': L__J000 FEET 0 100 METERS -.:uera bom TOPO!t:M1\�rioml OeampYic Flatdim(m.x.tcFo.com) AAG20-063 8947 Buttonwood Lane NE, Olympia, WA 98516 12 Phone#: (360)491-5155 Cell #: (360)481-6677 ILL cAN GwTtcicA FIGURE 2. SITE PLAN AAG20-063 8947 Buttonwood Lane NE, Olympia, WA 98516 13 Phone#: (360)491-5155 Cell#: (360)481-6677 1 NOTES This is not a survey. This map is a presentation of information from county, state,and federal agencies, client provided information, and onsite observations;for discussion purposes of the report with which this map is Contour Interval5 It included. Scale I Inch 200 It id Site Geology Qpu — Pleistocene glacial& nonglacial deposits,pre-Vashon sediments undifferentiated. Site son 1 % Ab Alderwood gravelly sandy loam, 8 to 15 percent slopes Ac Alderwood gravelly sandy loam, 15 to 30 percent slopes Ad Alderwood gravelly sandy loam, 30 to 50 percent slopes i 4p By: Site plan 22230-24-00000,22230-23-ONIO,& All American Geotechnical,Inc. Project P it Number: Parcel Numbers: 22230-21-00021 Figure 8947 Buttonwood Lane NE Number: BWJ Proposed Home Unassigned Address on East State Route 6 Olympia,Washington 98516 AAG20-003 awn Union,WA Applicant Name: Brian Stefimko Site Address: ;001- _._. - ?may... � r- _ •. �I Contour Interval=5 ft ~f Scale l inch=200 ft -- 0 t00 200 300 400 X.^ , F i , _ , _ p `v �f ^ 1 4 �211Q' 1 i LM I 1'. `. MASON COUNTY Submittal Checklist COMMUNITY SERVICES Geotechnical Report tom,% Building.Planning.Environmental Health.Community Health 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 International Residential Code Sections R403.1.7 for foundations on or adjacent to slopes, Section R403.1.8 for expansive soils orsection 1808.7.1 of the Intemational Building Code Section for Foundations on or adjacent to slopes. Applicant/Owner 2 -(a S� lI- parcel# zz,Z 30 -2q-yovv �� - ,/a cttj Z� Site Address o (1) (a) A discussion.of general geologic conditions in the vicinity of the proposed development, �C�/1 i iprj Located on page(s) AI V -D N (b) A discussion of specific soil types, oV 8 ?o?o Located on page(s) 7-0 615 VV. Alder s (c) A discussion of ground water conditions, treat Located on page(s) CY (d) A discussion of the upslope geomorphology, pLti1�'{1�T1��11��11 NG Located on page(s) c^ (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) y (2) A site plan which identifies the important development and geologic features. S C1 Located on Map(s) 8 F; �� A {- �A 9 (3) Locations and logs of exploratory holeps or probes. Located on Map(s) (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) C7 (5) A minimum of one cross section at a scale which adequately depicts the subsurface profile, and which incorporates the details of proposed grad changes. Located on Map(s) (6) A description and results of slope stability analyses performed for both static and seismic loading conditions. examine worst case failures.The analysis should include the Simplified 's Method ofied Bisho Analysis should exam y p P 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 as value of 0.15. Located on page(s) / - r 0 (7) (a) Appropriate restrictions on placement of drainage features, Rev. February 2018 Located on page(s (b) Appropriate restrictions on placement of septic drain fields, Located on page(s) 1 Z (c) Appropriate restrictions on placement of compacted fills and footings, Located on page(s) /-Z—/ (d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes. Located on page(s) 3 (e) Recommended setbacks from the,landslide hazard areas shoreline bluffs and the tops of other slopes.0 Located on page(s) (8) Recommendations for the preparation of a detailed clearing and grading plan which specifically identifies vegetation to be removed, a schedule for vegetation removal and replanting, and the method of vegetation removal. Located on page(s) 13 (9) Recommendations for the preparation of a detailed temporary erosion control plan which identifies the specific mitigating measures to be implemented during construction to protect the slope from erosion, landslides and harmful construction methods. Located on page(s) /3 (10) An analysis of both on-site and off-site impacts of the proposed development. Located on page(s) 1 4-1 (11) Specifications of final development conditions such as,vegetative management, drainage, erosion control, and buffer widths. / Located on page(s). (12) Recommendations for the preparation of structural mitigation or details of other proposed mitigation. Located on page(s) / (13) A site map drawn to scale showing the property boundaries,scale, north arrow, and the location and nature of existing and proposed development on the site. �1 Located on Map(s) %yu%�1 Y- hereby certify under penalty of perjury that I am a civil engineer licensed in the State of Washington with specialized knowledge of geotechnicallgeological 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 `fit �� h• f Geotechnical Report, dated f-( .1 C> 1020 , and entitled z- meets all the requirements of the Mason County Resource Ordinance, Geologically Hazardous Areas Section, is complete and true, that the 2439 ��s assessment demonstrates conclusively that the risks posed by the cenSed landslide hazard can be mitigated through the included geotechnical Cl tts Dead Cushman design recommendations, and that all hazards are mitigated in such a (Signature and Stamp) manner as to prevent harm to property and public health and safety. Page.2 of 2 Disclaimer.,Mason County does not certify the quality of the work.done in this Geotechnical Report. GEOTECHNICAL REPORT RESIDENTIAL DEVELOPMENT SITE EAST STATE ROUTE 106 UNION, WASHINGTON PREPARED FOR BRIAN STEFANKO BY ALL AMERICAN GEOTECHNICAL O LYMPIA, WASHINGTON FEBRUARY 20, 2020 ALL AMERICAN GEOTECHNiCAL CONTACT INFORMATION PREPARER INFORMATION AAG PROJECT NUMBER: AAG20-003 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: BRIAN STEFANKO TELEPHONE: (360)633-9289 BILLING ADDRESS: BRIAN STEFANKO 4775 NE LAMMS LANE POULSBO,WA 98370 SITE ADDRESS: 11510 E STATE ROUTE 6 UNION,WASHINGTON EMAIL BRIANSTEFANKO@GMAIL.COM PARCEL NUMBERS 22230-24-00000 22230-23-00010 22230-21-00021 GPS LOCATION: N470 22'08.57" W1220 59' 01.69" (Inside parcel 22230-24-00000) AAG20-003 8947 Buttonwood Lane NE,Olympia,WA 98516 2 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL Am , cm GaortcnNicAL SCOPE OF UNDERSTANDING BRIAN STEFANKO 4775 NE LAMMs LANE POULSBO,WASHINGTON 98370 RE: GEOTECHNICAL REPORT PROPOSED RESIDENCE 11510 E STATE ROUTE 106 UNION,WASHINGTON N470 21' 18.15" W 1230 05'59.23" PARCELS: 22230-24-00000 22230-23-00010 22230-21-00021 FEBRUARY 20,2020 Dear Mr. Stefanko: Brian Stefanko (client) hired All American Geotechnical, Inc. (AAG) in August 2018 to do a preliminary site evaluation for a residential property with outbuildings on one or more of three lots in Mason County, Washington. AAG was subsequently asked in January 2020 to do a geotechnical report for the property in anticipation of development with a single-family dwelling. The following is the report written to comply with the Mason County Requirements in the Critical Areas Ordinance in accordance with the Submittal Checklist For a Geotechnical Report for the above property near the city of Union in Mason County, Washington. The site is to be developed for residential and other rural uses associated with a single family residence. As per client request, we did a relevant site visit and a search of public documents. We have provided two stamped copies for submission and for your records. Landslide hazards will be noted and analyzed in text. Other geotechnical information is likewise included. We appreciate this opportunity to be of service to you and we look forward to working with you in the future. If you-have any questions.concerning the above items,the procedures used, or if we can be of any further assistance please call us at the phone number listed below. of as `aye fo Respectfully Submitted, ALL AMERICAN GEOTECHNICAL,INC. 1-2-O /C 2439 @used eo Curtis D. Cushman, L.G.,L.E.G. Senior Engineering Geologist AAG20-003 )nwood Lane NE, Olympia, WA 98516 3 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AUMCAN GROTECHNICAL TABLE OF CONTENTS SCOPE OF UNDERSTANDING 3 1) SITE CONDITIONS 5 SURFACE CONDITIONS 5 A) SITE GEOLOGY 6 B) SOIL TYPES 7 C) GROUND WATER CONDITIONS 8 D) UPSLOPE GEOMORPHOLOGY 8 E) UPSLOPE WATERBODIES AND WETLANDS 8 F) LANDSLIDE ACTIVITY 8 2) SITE PLAN 8 3) EXPLORATORY HOLES OR PROBES 9 4) PROPOSED DEVELOPMENT 9 5) CROSS SECTION 9 6) SLOPE STABILTY ANALYSIS 9 SEISMIC LIQUEFACTION HAZARD 1 I GEOSEISMIC SETTING 1 1 LATERAL EARTH PRESSURES 1 I CONCLUSIONS AND RECOMMENDATIONS 14 PROVISIONS 15 READ THESE PROVISIONS CLOSELY 15 REFERENCES 16 APPENDIX 18 2015 AASHTO DESIGN SPECIFICATIONS 19 SLOPE MODELS 20 STATIC MODEL A-A' 20 DYNAMIC MODEL A-A' 21 STATIC MODEL B-B' 22 DYNAMIC MODEL B-B' 23 STATIC MODEL C-C' 24 DYNAMIC MODEL C-C' 25 FIGURE 1 VICINITY MAP 26 FIGURE 2. SITE PLAN 27 FIGURE 2A. INSET 28 FIGURE 3. EROSION CONTROL NOTES 29 AAG20-003 8947 Buttonwood Lane NE,Olympia,WA 98516 4 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AKMCAN GROTECKNICAL INTRODUCTION This report summarizes the results of our geotechnical study of the parcel herein described. One proposed building site is in the northwesternmost part of a square parcel of 40 acres (PN 222230-24- 00000)that is currently undeveloped. Another building site is located on another area of reduced slope in the southwestern part of this parcel. This is referred to as the Alternative Home Location on Figure 2. Other parts of the three parcels are suitable for some aspects of development, notably on parcel 22230- 23-00010. In general, the property is located on hilly terrain with slopes of varying degrees with Landslide Hazard Areas found notably on the sides of a stream that crosses the property from southeast to northwest, crossing the third parcel (PN 22230-21-00021) to drain into Hood Canal after crossing State Route 106 in a culvert. Our understanding of the project is based on our discussions with the client. The client plans to develop the property with a residence and outbuildings and develop a road to access these units. Access to the proposed work site would be by private road directly from E State Route 106 east of Union, Washington. This geotechnical report and the checklist for Mason County involves the following: 1. A review of the available geologic, hydrogeological and geotechnical data for the site area. 2. A detailed geologic reconnaissance of the site area and surrounding vicinity. 3. Investigation and identification of shallow subsurface conditions at the site by characterizing the exposed soil, sampling, and reviewing published well logs. 4. Comparison of the site to published geologic maps, previous field investigations, and open file reports. Inspection of aerial photographs to determine the geomorphology of the site. 5. Evaluation of the landslide, erosion, and seismic hazards at the site per the Mason County Critical Areas Ordinance regulations (as of January 1, 2007). 6. Slope modelling. A number of slopes near the proposed building sites exceed a slope of 40% and are greater in height than 10 feet. These are considered Landslide Hazard Areas (LHA) Therefore, Mason County requires that a geotechnical report be prepared in accordance with the Mason County Resource Ordinance Sections 17.01.100 through 17.01.104. 1) SITE CONDITIONS SURFACE CONDITIONS The proposed location for rural residential development is located either near the northwest part of the client property or in its central southwest area. The client property near the proposed building sites slopes moderately to the northwest with steeper slopes on the stream to the east. The property overall is basically covered with secondgrowth timber no more than 30 years old. There is a terrace along the main access, an old logging road, mainly in PN 22230-23-00010 which extends well into PN 22230-24-00000 to the east. This ends roughly around the 100 foot contour near the northwestern building site. On the AAG20-003 8947 Buttonwood Lane NE,Olympia, WA 98516 5 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AmndcAN GEonc'NNWAL Zq steeper upper slopes and well within PN 22230-23-00000, GIS contours indicate another area for the Alternative Home Site suitable for building is around the 295 foot contour. Other areas are feasible albeit on steeper slopes which would be outside designated Landslide Hazard Areas. Curtis D Cushman, L.E.G. of AAG conducted a partial site reconnaissance on August 18, 2018. Blaise Jelinek E.I.T. of AAG visited the site with the client on Monday February 10, 2020. The purpose of a site visit is to physically observe the property and adjacent properties in order to identify any recognized geologic conditions. Visual observations were documented. The three parcels are almost entirely undeveloped. Only the abovementioned logging road is presently available for vehicle access. The trees are generally straight and vertical with only a few showing limited creep and showing no other signs of slope movement. A) SITE GEOLOGY The following is taken from the Mason Lake 7.5-minute Quadrangle, Mason County, Washington; by Derkey, et al.; 2009; DNR Open File Report 2009-06. The residence will be constructed on Pre-Vashon sediments (Qpu)described briefly as follows: Qpu -Pre-Vashon sediments, undifferentiated(Pleistocene)—Composite unit of glacial and nonglacial gravel, sand, silt, and clay beneath Vashon till; consists of sediment rich in northern provenance clasts; gray to tan; often iron-oxide stained; moderately to well rounded;poorly to moderately well bedded; consists of units that are not separable at map scale, due to poor exposure; may include some Vashon advance outwash; most commonly recognized in water wells in the quadrangle and depicted in cross sections... As a pre-Vashon deposit, this has been compacted by the Fraser ice-sheet and is suitable for construction in general. The nearest water well shows variable lithology but is too far away from the client property to be of use. According to the CZAW map #MA_7ith jpg, the site is almost entirely is in the Intermediate zone (I), with stable areas (S) above it. The CZAW maps shows no major (e.g. mapable) landsides in the immediate area. There are no nearby mapped faults and the nearest active fault zone is the Tacoma Fault near Allyn, Washington, to the north. Seismic acceleration is important in modelling the slope stability as the Puget Sound area is in an active tectonic zone and although this fault does not pose an immediate hazard to the proposed building project, low levels of seismic activity are not uncommon and there is always the possibility of a major shock. AAG20-003 8947 Buttonwood Lane NE,Olympia, WA 98516 6 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AmERic AN GiEoucH I L B) SOIL TYPES The soil in the areas of the proposed northwestern development is described by the USDA Web Soil Survey as: Ac—Alderwood gravelly sandy loam, 15 to 30 percent slopes Map Unit Setting • National map unit symbol: 2t627 • Elevation: 0 to 1,000 feet • Mean annual precipitation: 25 to 60 inches • Mean annual air temperature: 46 to 52 degrees F • Frost-free period: 160 to 240 days • Farmland classification: Farmland of statewide importance Map Unit Composition • Alderwood and similar soils: 85 percent • Minor components: 15 percent • Estimates are based on observations, descriptions, and transects of the mapunit. Description of Alderwood Setting • Landform: Ridges, hills • Landform position (two-dimensional): Backslope • Landform position (three-dimensional): Side slope, nose slope, talf • Down-slope shape: Linear, convex • Across-slope shape: Convex • Parent material: Glacial drift and/or glacial outwash over dense glaciomarine deposits Typical profile • A - 0 to 7 inches: gravelly sandy loam • Bwl - 7 to 21 inches: very gravelly sandy loam • Bw2 - 21 to 30 inches: very gravelly sandy loam • Bg - 30 to 35 inches: very gravelly sandy loam • 2Cdl - 35 to 43 inches: very gravelly sandy loam • 2Cd2 - 43 to 59 inches: very gravelly sandy loam Properties and qualities • Slope: 15 to 30 percent • Depth to restrictive feature: 20 to 39 inches to densic material • Natural drainage class: Moderately well drained • Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately low (0.00 to 0.06 in/hr) • Depth to water table: About 18 to 37 inches • Frequency of flooding: None • Frequency of ponding: None • Available water storage in profile: Very low (about 2.7 inches) AAG20-003 8947 Buttonwood Lane NE, Olympia, WA 98516 7 Phone#: (360)491-5155 Cell #: (360)481-6677 ALL AMERICAN GEOTECHNICAL The Alternative Home Location building site is mapped by the USDA WSS as being on Ad Alderwood gravelly sandy loam 30 to 50 percent slopes. This mapping is incorrect as the slopes are only locally over 40%. At the building site, the soil would also be Ac Alderwood. This appears to be the soil that is seen in the road cuts and elsewhere on-site. The soil is not important to the placement of the residence as it is relatively thin and likely to be removed in developing the footings. C) GROUND WATER CONDITIONS The ravine to the east commonly has flowing water. There are other, smaller drainages on the large property. No other water was seen. There was no evidence of active surface erosion at the building sites or around the entrance road to the lower terrace. D) UPSLOPE GEOMORPHOLOGY The slope continues up to the south to a ridge following the glacial scour trend of northeast-southwest approximately 600 feet to the south of the property line. This does not constitute an immediate geotechnical hazard to the parcel. E) UPSLOPE WATERBODIES AND WETLANDS There are none. F) LANDSLIDE ACTIVITY The 7.5-minute quadrangle shows a few small landslides in the stream to the east. This is an ongoing process due to over-steepened conditions in the valley walls. A large landslide on the Canal is located a half mile to the west, but this is shown in the cross-section as very thin as it is not differentiated from the underlying units. The adjacent mapping on the Union Quadrangle has these as mass-wasting deposits and not landslides, and they do not appear to be of concern for the client property. LiDAR from the Mason County GIS derived from the Puget Sound Lidar Consortium (g47122c81) shows no evidence of any landslides in the area around the site. In addition, the mapped landslides do appear to be shallow mass-wasting events and not deep-seated. There was no evidence of current on-site landslide activity. ee y 2) SITE PLAN Please see Figures 2 and 2A in the appendix. AAG20-003 8947 Buttonwood Lane NE,Olympia, WA 98516 8 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL Amman GRoTiEcuNicAL 3) EXPLORATORY HOLES OR PROBES The site was surface examined along the access road, in exposures on the property, and as sampled as located on Figures 2 and 2A. 4) PROPOSED DEVELOPMENT This will be a residence in one of two proposed locations and nearby outlying buildings to be located later. 5) CROSS SECTION Three (3) different cross-sections are in the Appendix. They are along lines A-A', B-B', and C-C' which intersect the potential building sites. 6) SLOPE STABILTY ANALYSIS The Slope Stability Analysis is as follows following the Mason County Resource Ordinance of 2009: 17.01.1OOE5(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 Bishops Method of Circles The minimum static safety factor is 1.5, the minimum seismic [dynamic] safety factor is 1.1 and the quasi static analysis coefficients should be a value of 0.15. Slope stability was modeled using the GALENA 6.1 program in both static and dynamic conditions (ca= 0.298). "Static" condition refers to an "as is" state of a given slope. "Dynamic" puts seismic acceleration into the model for earthquake conditions. The factor for ground acceleration (ca) was determined from the Peak Ground Acceleration from the USGS Seismic Design Maps, included in the Appendix. The surface soil was field classified in the range of a GP, a sandy gravel. These units are consistent with the description of the Qpu Glacial and Non-Glacial Sediments. The site was modeled as monolithic unit. Groundwater was not included in the model. Parameters used for the subsurface material are presented in the table below. AAG20-003 8947 Buttonwood Lane NE,Olympia,WA 98516 9 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL Table 1. Modeling Parameters for Subsurface Material Geologic Unit Unit Weight Cohesion Phi Angle Qpu--Glacial&Non-Glacial Deposits 1 1 4W 34 Factors of safety were determined using the Bishop (semi-circular) method. A ground water table was not included in the model, as none was encountered. Under static conditions, the slopes did not show susceptibility to deep-seated failure that would cause damage to the existing development. See Appendix for model output and cross-sections. Under dynamic loading (Ca=0.298), the computations demonstrated that the development is safe and not susceptible to a deep-seated movement. The following are the Factors of Safety (FoS) attained for the sections with respect to their current topographical representation. General information for the slope profiles and the initial positions for analysis is presented in the following table. Table 2. Initial Positions,Variance, and Findings Analysis Load Across Anal sis Initial Positions(Anal sis Ran e) Configurations Factor of Number Building Envelope :1)e JLower tJ )er lRadius JAnalyzed Safety Cross-Section A-A' ................I 1500# 34-108 ;Static ;90(40) :430(100) :410(40) 125,001 2.01 ........... ...........r..........................I............. .................e........... Analysi. _ -- 1500#_34-108 ........ (40)...: Cross-Section B-B' Ana1�_sis � , 1500# 359-432�.�:Static- _268(40)_- .360(30) �160-(20)--- -- 125.001- ---:-- 3.27 -- ---------- -- .......... ---- - - - - - - - - 11A sis 4 ; I500# 359-432 ;Dynamic _268(40) :360(30) :160(20) ; ___125.001_ 1.65 ----------------------- -------------------------------- - - ----- Cross-Section C-C' ------.---------- r------------r----- --- --r---------------------- ------r-------- Analysis_3.�.•.1500# 372-424 :Static :64(50) :372(150) :650(50) 125,001 2.95 analysis 4.j___1500# 372 424 Dynamic :64_(50) :372(150) :650(50) 125.001 1.36 ..J.. ....---.L. ......................L-...........J....----------- L--......... These calculated Factors of Safety (FoS) meet or exceed code standards. Thus, based on our slope models representing critical slopes at the subject site, it is apparent that the modelled sites are not susceptible to damage by deep-seated movements or instability The values input were selected to be as conservative as possible so the FoS are likely higher. The graphic output of these data is presented in the appendix,pages 20-25. AAG20-003 8947 Buttonwood Lane NE,Olympia,WA 98516 10 Phone#: (360)491-5155 Cell #: (360)481-6677 ALL AmEktcAN GEOTIECHNICAL SEISMIC LIQUEFACTION HAZARD The Liquefaction Susceptibility Map of Mason County, Washington by Palmer, Magsino, Poelstra, Bilderback, Folger, and Niggemann (September 2004) maps the site area as having a Very Low to Low liquefaction potential. The Site Class Map of Mason County, Washington by Palmer, Magsino, Bilderback, Poelstra, Folger, and Niggemann (September 2004) maps the area as site Class C to D. Site class C is a very stiff soil or soft rock and class D is stiff soil. GEOSEISMIC SETTING According to the Seismic Zone Map of the United States (Figure 1613.3.1(1)) contained in the 2015 International Building Code (IBC), the project site is located where the maximum spectral response acceleration is greater than 50 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): 1.42g(Fa= 1.05) • Spectral response acceleration, 1-second period(SM1): 0.876g(F,= 1.55) • Peak Ground Acceleration 0.596 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 GP: • 0 (soil friction angle) 34degrees • Ko (at rest earth pressure coefficient) 0.470 • Ka(active earth pressure coefficient) 0.283 • Kp (passive earth pressure coefficient) 3.54 • y (soil unit weight) 118 pcf 7) RESTRICTIONS A) PLACEMENT OF DRAINAGE FEATURES All ground surfaces, pavements and sidewalks should be sloped away from the residence and associated structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and/or catch basins and tight lined into the appropriate drainage facilities. We recommend that conventional roof drains be installed. Footing drains shall be installed for the proposed structure. The roof drain should not be connected to the footing drain. For footing drains, the drain invert should be below the bottom of the footing. AAG20-003 8947 Buttonwood Lane NE, Olympia,WA 98516 11 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL ARRIN GR®THNIL Typical drainage control measures are included on Figure 3 in the appendix. The soil will accept downspout and other drainage located at least 5 feet from the edge of the footing of the residence. Figure 3 shows recommendations for a tightline system which is not likely a better option for this property. Drainage should be such that there is no flow onto the steep slopes to the east at the northwestern site. B) PLACEMENT OF SEPTIC DRAIN FIELDS The drain field is located as mapped on Figure 2. The drainfields will be well outside the LHA and buffer. Domestic water is from a well whose proposed location is mapped on Figure 2. C) PLACEMENT OF COMPACTED FILLS AND FOOTINGS RECOMMENDATIONS FOR SITE PREPARATION The area is forested and the trees shall be cleared as needed for construction. All areas to be excavated should then be cleared of deleterious matter including any debris, duff, and vegetation. All deleterious material will be removed and sub-soils reached for the footings for the construction of slab and/or footings. Any material that is excavated may be stockpiled and later used for erosion control and/or landscaping. Surficial material unsuitable for these tasks should be removed from the project site. No foundation elements shall be constructed on"untested"fill material. If demonstrated to be acceptable, the sand/gravel sedimentary material on site may be suitable for re-use as structural fill. Where placement of fill material is required, the exposed subgrade areas should be compacted to a firm and unyielding surface prior to placement of any fill. Over-excavation in any building area should be 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 AAG20-003 8947 Buttonwood Lane NE, Olympia,WA 98516 12 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AME,RICAN GEOTE,CRNICAL 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 At the northwestern site, the 50-foot vegetation buffer from the toe of the LHA will be intruded upon by r the proposed residential construction. This may be done in keeping with the requirements of timbering the site for development. The slopes are such that erosion should not be a limiting factor. The LHA, which is on the upslope to the east and southeast, shall not be disturbed. The Alternative Home Location site lies near a few mapped LHAs. As proposed, it lies outside of any LHA and buffer. E) SETBACKS The site is outside of the acceptable hazards as defined by the slope stability model and the resultant Factors of Safety. The geotechnical setback is seen by the 200'well diameter on Figures 2 and 2A. r 8) CLEARING AND GRADING PLAN Timber clearing will be needed for either residence. No grading is anticipated except to develop flat building sites and create an acceptable entry road. "No Disturb" zones will not be required. No formal plan should be needed as long as safe procedures are employed with the clearing in keeping with Mason County regulations. All job site safety issues and precautions are the responsibility of the contractor providing services and/or work. 9) EROSION CONTROL PLAN It is our opinion that the potential erosion hazard of the sites is not a limiting factor for the proposed developments. Although removal of natural vegetation will take place inside the 50-foot buffer for the northwestern home site, simple erosion control methods will reduce or eliminate any potentia 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 near the LHAs of either site. The possibility of down-slope contamination is highly 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 protective vegetative cover, or otherwise protected. Surface AAG20-003 8947 Buttonwood Lane NE,Olympia,WA 98516 13 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL Awrdcm GrwrEaANTCAL water should not flow toward or over any steep slopes. Drainage pipes should not daylight on any steep slopes. A revegetation plan should not be required. When residential plantings or any plantings on the periphery of the residential area and the slopes are planned, native species should be considered as the primary vegetation in areas away from lawn and ornamental plantings. Shallow rooted species, such as grass, should be planted closer than 10 feet from underground drainages. Densely rooted evergreen shrubs are preferable than tree species on slopes greater than 15% gradient. Tall trees may become unstable in wet soils under high wind conditions. In general, the steep sides of the ravine should be left in a natural condition unless erosion or sloughing eventually pose a hazard to the residence. 10) ON AND OFFSITE IMPACTS There should be no notable on- or offsite impacts if the project is completed according to the recommendations of this report and in accordance with all regulations and to the high standards and practices of the building contractor. No geotechnical impact is anticipated in the construction of the residence at either location. 11) FINAL DEVELOPMENT CONDITIONS All final conditions will follow the design by the Engineer of Record and compliance with all regulatory agencies. If this and the above recommendations are followed, final development conditions will be achieved. 12) STRUCTURAL MITIGATION There is no structural remediation to be done. 13) SITE PLAN Please see Figure 2. CONCLUSIONS AND RECOMMENDATIONS Based on the results of the site reconnaissance, subsurface observations, and our experience in the area, it is our opinion that the proposed sites are suitable for the proposed improvements. These are among several buildable locations. As preliminarily located, the proposed structures would not undermine adjacent slopes. Disturbance of vegetation within the northwestern site may be managed to avoid possible erosion. AAG20-003 8947 Buttonwood Lane NE, Olympia, WA 98516 14 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AmERICAN Gino acnNicA L PROVISIONS GENERAL We have prepared this report for the exclusive use of Brian Stefanko and his authorized agents for the proposed improvements in Mason County, Washington. Site inspections, research, and mapping have culminated in this report. This report is intended to meet the requirements of the Mason County Resource Ordinance. This report does not specify setbacks for: line-of-sight setbacks, FWHCA setbacks, eagle tree setbacks, wetland setbacks, or property line setbacks. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. No warranty or other conditions, expressed or implied, should be understood. Clients and property owners must understand that, while a slope may be found to have an acceptable Factor of Safety related to deep-seated mass wasting, surficial failure and landslides can and do occur on steep slopes. The property owners should monitor the stability of their property following construction. Moreover, acceptable Factors of Safety do not guarantee there cannot be failures. It is the responsibility of the property owners to understand that there are always risks in building on or near steeply sloped areas. 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. AAG20-003 8947 Buttonwood Lane NE,Olympia,WA 98516 15 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AmrmtcAN GmTEcHNICAL REFERENCES MAPS DeLorme 3-D TopoQuads(2002),Source Data USGS,Yarmouth,Maine. Derkey, R. E. et al., (2009); Geologic Map of the Mason Lake 7-5-minute Quadrangle, Mason County, Washington; DNR Open File Report 2009-06 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. Polenz. M.,(2011);Geologic Map of the Skokomish Valley and Union 7.5-minute Quadrangles, Mason County, Washington, DNR Open File Report 2010-03 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. Bloom(1991),Geomorphology,published by Prentice-Hall, Inc.,Upper Saddle River,New Jersey. International Code Council, Inc.(2006),2006 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. McCarthy(1993), Essentials of Soil Mechanics and Foundations,published by Prentice-Hall, Inc., Upper Saddle River, New Jersey. Ness, Fowler,Parvin(1960),The Soil Survey of Mason County, Washington, USDA Soil Conservation Service, in cooperation with the United States Department of Agriculture, and Washington Agricultural Experimental Station, and the Soils Conservation Service. Parks, Neal, Koloski, Laprade, Molinari, Butler, and Lorentson (November 2006), Guidelines for Preparing Engineering Geology Reports in Washington, published by Washington State Geologist Licensing Board,Olympia,Washington. Sowers(1979),Introductory Soil Mechanics and Foundations: Geotechnical Engineering,Macmillan Publishing Co.,Inc. Washington State Department of Transportation (WSDOT)(2005),Standard Specifications for Road, Bridge, and Municipal Construction 2006 M41-10,prepared by WSDOT Engineering Publications,P.O. Box 47408,Olympia,Washington. AAG20-003 8947 Buttonwood Lane NE,Olympia, WA 98516 16 Phone#: (360)491-5155 Cell #: (360)481-6677 ALL AN GROTIRCHNICAL WEBSITES 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://pugetsoundl idar.ess.washington.edu/lidardata/index.html) Slope Stabilization Erosion Control Using Vegetation A Manual of Practice for Coastal Bluff (http://www.ecy.wa.govibiblio/9330.htmi) Vegetation Management Guide for Puget Sound Bluff Property Owners (http://www.ecy.wa.gov/biblio/9331.htm1) 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/coastalatias/viewer.htm) AAG20-003 8947 Buttonwood Lane NE,Olympia, WA 98516 17 Phone#: (360)491-5155 Cell #: (360)481-6677 APPENDIX USGS Seismic Design Specifications Slope Models Figure 1. Vicinity Map Figure 2. Site Plan Figure 2a. Site Plan Inset Figure 3. Erosion Control Notes. AAG20-003 8947 Buttonwood Lane NE, Olympia,WA 98516 18 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GROTECHNICAL 2015 AASHTO DESIGN SPECIFICATIONS Search Information Redmond Seattle ° Address: 47.371, o 116 it Coordinates: 47.371,-122.988 Nat Olnampic l Forest It Kent Elevation: 116 ft ° Timestam 2020-01-21To1:13:09.762Z Tacoma p' Shelton o o Rt.i'13up Hazard Type: Seismic 1oi Olympia Reference IBC-2015 nGo gle Lima ° Map Reportemapertm Document: Risk Category: III Site Class: D MCER Horizontal Response Spectrum Design Horizontal Response Spectrum Sa(g) Sa(g) 1.40 1.20 0.80 1.00 0.60 0.60 0.60 0.40 0.40 0.20 0.20 0.00 0.00 0 5 10 15 Period(s) 0 5 10 15 Period(s) Basic Parameters Name Value Description SS 1.42 MCER ground motion(period--0.2s) S1 0.584 MCER ground motion(period=1.0s) SgtS 1.42 Site-modified spectral acceleration value SMI 0.876 Site-modified spectral acceleration value Sus 0.947 Numeric seismic design value at 0.2s SA SDI 0.584 Numeric seismic design value at 1.0s SA Additional Information Name Value Description SDC D Seismic design category Fa 1 Site amplification factor at 0.2s F 1.5 Site amplification factor at 1.0s CRS 0.981 Coefficient of risk(0.2s) CRI 0.934 Coefficient of risk(1.0s) PGA 0.596 MCEG peak ground acceleration AAG20-003 8947 Buttonwood Lane NE, Olympia, WA 98516 19 Phone#: (360)491-5155 Cell #: (360)481-6677 ALL AMERICAN GEOTECHNICAL SLOPE MODELS STATIC MODEL A A - � d co m � \ J 2 in7 ƒ / « _ a £$ § B R # ■ / ƒ . Es J \ a \ § «& K : § \3 § @ 2 d § Ac � 8 � a � � 7 � � 2k $ § k k @ A @ 2 2 ° # co 2 � ƒ AAG2-0 8947 Buttonwood Lane NE, Olympia, WA 98516 00 Phone R (6)4!al55 Cell% (6)4al-67 ALL Ar&ktt4 GoTctwiL DYNAMIC MODEL A-A' to e0 N � � o P-Z a C� itl .cn co pU?? _U � co v m 0 N N d c� gEg O 1 N lL J Q C N LV 4 G1 CJ AAG20-003 8947 Buttonwood Lane NE,Olympia, WA 98516 21 Phone#: (360)491-5155 Cell #: (360)481-6677 ALL AMERICAN GEOTECHNICAL STATIC MODEL B a` 2 d cc § § � # 72 A2 } f ® ƒ C � CDwe f 2 2 a � — \ � � Ii \ � \ � � . § \ & : § , A \ § ƒ / a \ 2 s ` & kr. & N & § g 7 A @ 2 « 9 S o cn cnf V 9 � AAQ2-0 84 Buttonwood Lane NE, Olympia, WA9816 22 Phone* (6)4 1a155 Cell+ (6)481-677 ALL AUMCAN GROTECHNICAL DYNAMIC MODEL B B § � cc | -A . 'c E � / - a \� § N \ § 2 2 / . \ � ƒ ■ � 7 � c � pm « 0 ƒ $ � § & § § % ■ @ § ¥ q E � � 2 o k � R ) $ AAG2-0 8947 Buttonwood Lane\E Olympia, W&98516 23 Phone R (36)4&5I55 Cell+ (6)4l-67 ALL AwRicAN GKoTiEcitNicAL STATIC MODEL C-C' cV _ .m AC � � N � � V (75 rg a Y y ca m Ci 7S � cr W a Vi s M 8 � O ` 1 N O O O N N �i go Q Y w o Q y c5 59 8 .9 8 co CO AAG20-003 8947 Buttonwood Lane NE, Olympia, WA 98516 24 Phone#: (360)491-5155 Cell#: (360)481-6677 f ALL AKRICA Gr&oTrAcRIL DYNAMIC MODEL C-C' Y $_ cn M a 03 cn I w 4 rn 8 v 8 v r� 8 o � � U y gE Q o l r LL r Q .beV o J $3 O Q N E no C7 I AAG20-003 8947 Buttonwood Lane NE, Olympia, WA 98516 25 Phone#: (360)491-5155 Cell#: (360)481-6677 ALL AMERICAN GEOTECHNICAL FIGURE 1 VICINITY MAP 113'C1.000'W 123°00.000'W 122^59.000'W WGS84 122`58.000'W ILI o c r. / ❑ � ya O I y r ' 0 4' BOtl! } I ?,0 shady 8e.n us-V a-c f-zel Briian stefiltlo.. " 11510 East State Rout -- - Parcels: 2 24 00@ 0 (� O N ry 167 , - �P ¢0 / c N 123°01.000'W 123°00.000'W 122-59.000'W WGS84 122°58.000'W 0 S 1 WE I6''c 0 10061EE7 0 500 t000 MfTLOn Printed from TOPO?92001 Natio W Geopaphic Hdd*,(—rDt.eom) AAG20-003 8947 Buttonwood Lane NE, Olympia, WA 98516 26 Phone#: (360)491-5155 Cell #: (360)481-6677 ALL AmEpticAN GwTiEcHNIC L FIGURE 2. SITE PLAN AAG20-003 8947 Buttonwood Lane NE,Olympia, WA 98516 27 Phone#: (360)491-5155 Cell#: (360)481-6677 r� NOTES This is not a survey. This map is a presentation of information from county, state,and federal agencies, ; client provided information, and onsite observations;for ; discussion purposes of the - : Contour Interval=5 ft report with which this map is Scale 1 inch=200 ft included. ' l\_ 100 200 300 400 i Site Geology \ Qpu -- Pleistocene glacial& I nonglacial deposits,pre-Vashon sediments undifferentiated. ` I � I Site Soil Ab—Alderwood gravelly sandy loam, 8 to 15 percent slopes Ac--Alderwood gravelly sandy loam, Wash 15 to 30 percent slopes Ad --Alderwood gravelly sandy loam, 30 to 50 percent slopes \ LJ LJ 2439 g, used Ge Curtis Dean Cushman All American Geotechnical,Inc. Project D22230-24-00000,22230-23-00010, &22230-21-00021 Figure 8947 Buttonwood Lane NE Number: B Olympia,Washington 98516 AAG20-003 Ill 1510 East State Route 6 www.AllAmericanGeotechnical.com 2 ALL A tamtcm GaorEcnNicAL FIGURE 2A. INSET AAG20-003 8947 Buttonwood Lane NE,Olympia, WA 98516 28 Phone#: (360)491-5155 Cell#: (360)481-6677 -- i \ I I i r ' __......-_....._....- -- - -, y �t i `\ dG .s j ce \ as ed 00 �,. 1 sed j - ! i 1 , -. �, - _ ' I 11 _ f - Y I , Sa zpl r' I , i r , 1 , : : / ,,, ,` r 'fir•, ,..;!••\ / ► /' , I SCALE 7'=50' C.I.=5' ,U._. 20 '3 w 50 O b i /1 O O , I ` , All American Geotechnical, Inc. project Drawn By: Building Area 22230-24-00000,22230-23-00010, 8947 Buttonwood Lane NE Number: BWJ 2/18/20 Proposed Single Family Home Permit Number: Parcel Number: &22230-21-00021 Figure Olympia, Washington 98516 AAG20-003 Union,Washington Applicant Name: Brian Stefanko 11510 East State Route 6 2A www.AILAmericanGeotechnical.com Revisions: Site Address: ALL AMERICAN GromcwicAL FIGURE 3. EROSION CONTROL NOTES AAG20-003 8947 Buttonwood Lane NE, Olympia,WA 98516 29 Phone#: (360)491-5155 Cell #: (360)481-6677 • NOTES This is not a survey. This map is a presentation of information from county, state,and federal agencies, o °. ` `:`` ,`, ; \` ! / ..."— client provided information, and onsite observations; for discussion purposes of the Contour Interval 5 ft report with which this map is V/1 V • Scale 1 inch=200 ft • included. N, 0 100 200 300 400 RR A--- V V- F3EVIEWED FOR COMPLIANCE ON COUNTY r"ING DEPARTMENT Site Geology f Qpu — Pleistocene glacial& ire nonglacial deposits,pre-Vashon sediments undifferentiated. Site Soil Alderwood gravelly sandy loam, 8 to 15 percent slopes �?7 Alderwood gravelly sandy loam, 15 to 30 percent slopes 00010or 10 Alderwood gravelly sandy loam, 30 to 50 percent slopes \J Y 22230-24-00000,22230-23-00010, All American Geotechnical, Inc. Project Drawn BY: Site Plan Permit Number: Parcel Numbers: &22230-21-00021 Figure 8947 Buttonwood Lane NE Number: BWJ Proposed Home Olympia,Washington 98516 AAG20-003 1/18/20 Union,WA Applicant Name: Brian Stefanko Site Address: 11510 East State Route 6 2 www.AILAmericanGeotechnical.com ' , t 1100 , , 1 ....` ,4 •1 , 1 , as, + , , , r v v _. i , i , 4 :: '.. it ii 't •s • `,µi �,�� '\ , i \ + i � + sed i,. i 1 t t i �• \I I :t i ; ,. ; _ / Sa plyr O QoQi O SCALE 1•=50' C.I.=5s --f p s ,o p 3D 40 so Q5 All American Geotechnical, Inc. Drawn By: Building Area 22230-24-00000,22230-23-00010, Project Permit Number: Parcel Number: &22230-21-00021 Figure 8947 Buttonwood Lane NE Number: BWJ 2/18/20 Proposed Single Family Home Olympia, Whin 98516 Union,Washin on as Washington AAG20-003 Revisions: � Applicant Name: Brian Stefanko Site Address: 11510 East State Route 6 2A www.AlLkmericanGeotechnical.com REVIEWED FOR RECEIVED = CODE COMPLIANCE ' FILTER FABRIC MATERIAL 60"WIDE ROLLS MASON COUNTY USE STAPLES FAR WIRE RING TO ATTACH BRIC TO WIRE bULDING DEPARTMENT NOV 18 2"X2"X14 GAUGE WIRE 2U2U " rn FABRIC OR EQUIVALENT 615 W. Alder GENERAL EROSION CONTROL NOTES: 2'-0" 1. EROSION CONTROL MEASURES SHALL BE IN PLACE PRIOR TO THE BEGINNING OF CONSTRUCTION. THE PROJECT ENGINEER AND THE COUNTY //,A\ R UND SURFACE ///A\\: : 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'-6" :,:,,,,,,,- 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 SHALL BE ALLOWED. CARE SHALL BE TAKEN TO PREVENT MIGRATION L MjN M 2"X4"WOOD POSTS,STANDARD OR BURY BOTTOM OF FILTER OF SILTS TO OFF SITE PROPERTIES. > = j BETTER OR EQUAL ALTERNATE: MATERIAL IN 8"X12"TRENCH � < RR Sp Q'V6 FFT STEEL FENCE POSTS 3. THE CONTRACTOR SHALL MAKE DAILY SURVEILLANCE OF ALL EROSION CONTROL MEASURES AND MAKE ANY NECESSARY REPAIRS OR ADDITIONS TO THE EROSION CONTROL MEASURES. THE CONTRACTOR SHALL PROVIDE ::,•: _.,i,.y.�g.�.�:�t.. r:r:E;�;,;�:. ADDITIONAL EROSION CONTROL MEASURES AS DETERMINED NECESSARY '.': `-ter•'-.�`„ ''=:'" BY THE COUNTY INSPECTOR AND/OR THE PROJECT ENGINEER. FAILURE FILTER FABRIC 6" TO COMPLY WITH ALL LOCAL AND STATE EROSION CONTROL REQUIREMENTS MAY RESULT IN CIVIL PENALTIES BEING LEVIED 2"X2"X14 GAUGE WIRE r�. < `,�:>.f•_h.s . ::'-=ii:��... v c. ^'�;.,.:�.=:•.:, AGAINST THE CONTRACTOR AND/OR PROJECT OWNER. r; f.;• Y,_<;,-, r; iu.,, .;;;,;,... FABRIC OR EQUIVALENT GROUND SURFACE 5'-0" 4. DURING THE WET SEASON(NOVEMBER TO MARCH)ALL DISTURBED SOILS �'4:: =— "=`7i `�`"'` "�• ^�"`'='„`_' ' - _ ::�'-:4.`�.;��r;_•�;,; ::;.1=•c`�: :'l;z' '"`;�:'..;� SHALL BE STABILIZED WITHIN 48 HOURS AFTER STOP OF WORK. EROSION PROVIDE 3/4"-1 1/2"WASHED CONTROL MEASURES SHALL INCLUDE,BUT NOT BE LIMITED TO, COVERING THE EFFECTED AREA INCLUDING SPOIL PILES WITH GRAVEL BACKFILL IN TRENCH 12• PLASTIC SHEETING,STRAW MATTING,JUTE MATTING,STRAW MULCH, V````'•''""` 'v ' "i :." AND ON BOTH SIDES OF FILTER "._:�:�,,•�F:; ;;•:`. FENCE FABRIC ON THE SURFACE 8"MIN OR WOOD CHIPS. SEEDING OF THE DISTURBED AREAS SHALL TAKE PLACE AS WEATHER PERMITS. TIGHTLINE ANCHORED WITH TWO, 2"X4"WOOD POSTS 5. ALL SEEDED OR SODDED AREAS SHALL BE CHECKED REGULARLY 3 FOOT REBAR LENGTHS OR BOLTS. ALT:STEEL FENCE POSTS TO MAKE SURE VEGETATIVE COVERAGE IS COMLETE. AREAS SHALL BE FILTER FABRIC FENCE NOTES: REPAIRED,RESEEDED,AND FERTILIZED AS REQUIRED. 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 THE LENGTH OF THE BARRIER TO AVOID USE OF JOINTS. WHEN JOINTS 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 64NCH 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. BUILD114G 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. Ix 3. A TRENCH SHALL BE EXCAVATED APPROXIMATELY 8 INCHES WIDE AND 12 8. EXCAVATED MATERIAL SHALL BE PLACED ON THE UPHILL SIDE OF TRENCHES. �iy FLARE 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 9. TRENCH DEWATERING DEVICES SHALL BE DISCHARGED IN A MANNER THAT WILL QUARRY SPALL SUPPORT FENCE SHALL BE FASTENED SECURELY TO THE UPSLOPE SIDE NOT ADVERSELY AFFECT FLOWING STREAMS. DRAINAGE SYSTEMS OR -`i� OR ENERGY OF THE POSTS USING HEAVY-DUTY WIRE STAPLES AT LEAST 1 INCH OFFSITE PROPERTIES. DISPERSION DEVICE "`"`"•��• ='=`''"•"�`�==•'''' ';.;- s"� ` '=" '="`-�' ( 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 5. THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED WILL BE FILTERED BEFORE ENTERING THE CONVEYANCE SYSTEM. MINIMUM ONE FOOT WIDE AT THE TO THE FENCE AND 20 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 INCHES ABOVE THE ORIGINAL GROUND SURFACE. FILTER FABRIC SHALL SHALL BE PROTECTED FROM SILTATION. A MAXIMUM SLOPE OF 5 PERCENT. NOT BE STAPLED TO THE EXISTING TREES. MINIMUM 4 FEET 12.ALL DISTURBED AREAS SHALL BE SEEDED OR SODDED UPON COMPLETION LEVEL SECTION 6. WHEN EXTRA-STRENGTH FILTER FABRIC AND CLOSER POST SPACING IS 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&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.CATCH 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 22230-24-00000, 22230-23-00010, 8947 Buttonwood Lane NE BWJ Proposed Single Family Residence Permit Number: Parcel Number: &22230-21-00021 Figure Olympia, Washington 98516 2/18/20 Union, Washington Applicant Name: Site Address:Brian Stefanko 11510 East State Route 6 3 www.AllAmericanGeotechnical.com Revisions: I L