Loading...
HomeMy WebLinkAboutGEO2021-00107 Assessment for BLD2021-01377 - GEO Geological Review - 11/12/2020 Csba� DO PLANNING Geological Assessment Araujo Single Family Residential Property XXX E Main Street, Union Parcel No. 32232-50-06008, -09, -10 Mason County, Washington November 12, 2020 RECEIVED Project#20194 SEP - 6 2021 615 W. Alder Street Prepared For: Jeffrey Araujo 81 E 2nd Street Union, Washington 98592 Prepared By: Envirotech Engineering PO Box 984 Belfair, Washington 98528 Phone: 360-275-9374 c L}n1: 43045. k�Ql4ff-�` •-� J MASON COUNTY COMMUNITY SERVICES Geological Assessment Nuddmq.Naming.6nnronn ntal Health,Community Health Instructions: This checklist must be submitted with a Geological Assessment and completed,signed,and stamped by the licensed professional(s)who prepared the Geological Assessment for review by Mason County pursuant to the Mason County Resource Ordinance. If an item is found not applicable,the report should explain the basis for the conclusion. Note:Unless specifically documented, this report does not provide compliance to the International Residential Code Sections R403.1.7 for foundations on or adjacent to slopes, Section R403.1.8 for expansive soils or section 1808.7.1 of the International Building Code Section for Foundations on or adjacent to slopes. Applicant/Owner Jeffrey Araujo Parcel# 32232-50-06008,-09,-10 Site Address XXX E Main Street (1) A discussion of the geologic conditions in the general vicinity of the proposed development,with geologic unit designation based on referenced maps. Located on page(s) 5 (2) (a) A discussion of ground water conditions, Located on page(s) 6 (b) A discussion of the estimated depth to water, Located on page(s) 6 (c) A discussion of the quantity of surface seepage, Located on page(s) 6 (d) A discussion of the upslope geomorphology, Located on page(s) 3 (e) A discussion of location of upland waterbodies and wetlands. Located on page(s) 3 (3) The approximate depth to hard or dense,competent soil,e.g.glacial till or outwash sand. Located on page(s) 5 (4) A discussion of any geomorphic expression of past slope instability(presence of hummocky ground or ground cracks,terraced topography indicative of landslide block movement,bowed or arched trees indicating downslope movement,etc). Located on page(s) 4 (5) A discussion of the history of landslide activity in the vicinity, as available in the referenced maps and . records. Located on page(s) 8 (6) An opinion on whether the proposed development is within the landslide hazard area or its associated buffer or setback and the potential for landslide activity at the site in light of the proposed development. Located on page(s) 8 (7) A recommendation by the preparer whether a Geotechnical Report should be required to further evaluate site conditions and the proposed development of the subject property. Located on page(s) 12 (8) If the presence of a hazard is located within 300 feet of the proposed development,then the following are delineated on a geologic map/site map: (a) The area of proposed development, Located on map(s) n/a (b) The boundaries of the landslide hazard area(top, both sides,and toe), Located on map(s) n/a (c) The associated buffers(top,both sides,and toe), Located on map(s) n/a (d) Building or other setbacks(top,both sides,and toe), Located on map(s) n/a (9) 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) Site Plan(Appendix A) I, Michael Staten,hereby certify under penalty of perjury that I am a civil engineer licensed in the State of Washington with specialized knowledge of geotechnical/geological engineering or a geologist or engineering geologist licensed in the State of Washington with special knowledge of the local conditions. I also certify that the Geological Assessment dated November 12,2020 ,and entitled Arauio Single Family Residential Property ,meets all the requirements of the Mason County Resource Ordinance,Geologically Hazardous Areas Section,is complete and true,that the assessment demonstrates conclusively that the risks posed by the landslide hazard can be mitigated through the included geotechnical design recommendations,and that all hazards are mitigated in such a manner as to prevent harm to property and public health and safety. f� - 430415 11/12/2020 Disclaimer:Mason County does not certify the quality of the work done in this Geological Assessment. Page 2 of 2 TABLE OF CONTENTS 1.0 INTRODUCTION.................................................................................................................................1 1.1 PROJECT INFORMATION.................................................................................................................... 1 1.2 PURPOSE OF INVESTIGATION AND SCOPE OF WORK........................................................................ 1 2.0 SURFACE CONDITIONS....................................................................................................................3 2.1 GENERAL OBSERVATIONS..................................................................................................................3 2.2 ToPoGRAPHY.....................................................................................................................................3 2.2.1 Upslope Geomorphology............................................................................................................3 2.3 SURFACE DRAINAGE..........................................................................................................................3 2.3.1 Upland Water Bodies.................................................................................................................3 2.4 SLOPE AND EROSION OBSERVATIONS...............................................................................................4 3.0 SUBSURFACE INVESTIGATION.....................................................................................................5 3.1 FIELD METHODS,SAMPLING AND FIELD TESTING...........................................................................5 3.2 GEOLOGIC CONDITIONS....................................................................................................................5 3.3 SPECIFIC SUBSURFACE CONDITIONS.................................................................................................6 3.3.1 Groundwater............................................................................................................................... 7 4.0 ENGINEERING CONCLUSIONS......................................................................................................8 4.1 LANDSLIDE HAZARDS.........................................................................................................................8 4.1.1 Landslides and Slope Stability Analysis...................................................................................10 4.1.2 Surface and Subsurface Drainage...........................................................................................10 4.2 EROSION HAZARDS...........................................................................................................................10 4.3 SEISMIC HAZARDS.............................................................................................................................11 4.4 OTHER CONSIDERATIONS.................................................................................................................11 5.0 CLOSURE.............................................................................................................................................12 Appendix A-Site Plan Appendix B-Soil Information 1.0 INTRODUCTION Envirotech Engineering, PLLC. (Envirotech) has completed this geological assessment for a residential property located at 20 E Treasure Court, identified as parcel number 32232-50-06008, -09, -10 in Mason County, Washington. As presented herein, this assessment includes information pertaining to the Project in this Introduction Section;observations of the property and surrounding terrain in the Surface Conditions Section; field methods and soils descriptions in the Subsurface Investigation Section; and, assessments for landslides, erosion, seismic hazards, and other considerations in the Conclusions Section. An initial geological/ geotechnical evaluation of the project was conducted by Envirotech on November 03, 2020. It was determined that natural slopes between 15% and 40% were present within 300 feet of the project. Due to these slope grades, a geological assessment is required pursuant to landslide hazard areas of the Mason County Resource Ordinance(MCRO). During the evaluation and site visit by Envirotech, surface and subsurface conditions were assessed in order to determine if further geotechnical studies are required.After completion of the field work and applicable Project research,Envirotech prepared this geological assessment. 1.1 Project Information Information pertaining to the project was provided by the proponent of the property, and observations from a field visit by Envirotech.The proposed development is expected to consist of a new single family residence, on-site septic system, and other ancillary features typical of this type of development. Approximate site development with relation to existing site features are illustrated in the Site Plan in Appendix A of this report. 1.2 Purpose of Investigation and Scope of Work The purpose of this geological assessment was to evaluate the project in order to confirm that the proposed development is outside of any landslide hazard area and its associated buffers and setbacks as determined in the MCRO. The investigation included characterizing the general project surface and subsurface conditions,and evaluating the suitability of the soils to support the planned site development. In order to fulfill the purpose of investigation, the geological/ geotechnical program completed for the proposed improvements of the Project include: 0 Review project information provided by the proponent of the project; • Conduct a site visit to document the site conditions that may influence the construction and performance of the proposed improvements; 0 Define general subsurface conditions of the site by observing soils within test pit excavations, review well logs from existing wells near the Project, and evaluate geological and hazard maps depicting the site geology for the vicinity of the project; • Perform soils testing,such as visual classifications,to determine selected index properties of the soils; • Complete an engineering assessment supported by planned site alterations and the surface and subsurface conditions that were identified by the field investigation, soil testing, and applicable project research;and, • Establish engineering conclusions based on findings and anticipated development. Envirotech Engineering Geological Assessment PO Box 984 page 1 Pame132232-50-W08,-09,40 Belfair,Washington 99528 Mason County,Washington Ph. 360-275-9374 November 12,2020 L { 14 Vicinity Map from Mason County Website Envirotech Engineering Geological Assessment PO Box 994 page 2 Parcel 32232-50-06008;09;10 Belfair,Washington 99528 Mason County,Washington Ph. 360-275-9374 November 12,2020 2.0 SURFACE CONDITIONS Information pertaining to the existing surface conditions for the project was gathered on November 03, 2020 by a representative with Envirotech. During the site visit, site features were documented that may influence construction or reveal potential geological hazards.This Surface Conditions Section provides information on general observations, vegetation, topography, drainage and slope/erosion conditions for the project and surrounding areas. 2.1 General Observations The property is currently vacant land with few improvements and is surrounded by residential development.East 2°d Street extends along the south side of the property,and East Main Street is located immediately to the east. Vegetation on and near the property consists primarily of firs, maples, and other trees and shrubbery common to this area of the Pacific Northwest. An aerial photo of the Project and immediate vicinity is provided on the following page. 2.2 Topography The topographic information provided in this section was extrapolated from a public lidar source, and incorporated observations and field measurements. Where necessary, slope verification included measuring slope lengths and inclinations with a cloth tape and inclinometer. See the Site Plan in Appendix A for an illustration of the general slope indicators with respect to the planned development. Descending slopes exceeding 15%are located on and beyond the property. Average slope grades are approximately 23% with a vertical relief of approximately 25 feet. 2.2.1 Upslope Geomorphology Ascending grades are generally located to the south of the planned development. This slope is relatively minor within 300 feet of the Project, with no apparent slope grades of at least 30%. The upland area of the property is situated on a hillside and crest. Landforms are primarily of glacial origin with centuries of weathering overburden. Additional geomorphology that is pertinent to both upslope and downslope areas are provided in the Subsurface Investigation Section of this report. 2.3 Surface Drainage The majority of the stormwater runoff originating upslope from the anticipated development is expected to be moderate. Significant scour,erosion and sediment transport was not apparent near the project. However, excessive water flow atop the underlying hardpan creates surface seepage within the vicinity of the planned development. 2.3.1 Upland Water Bodies There are no apparent water bodies or wetlands located upslope from the planned development that would significantly influence the Project. Envirotech Engineering Geological Assessment PO Box 984 page 3 Parcel 32232-50-06008,-09,-10 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 November 12,2020 2.4 Slope and Erosion Observations The existing moderate slopes near the Project signal a potential landslide or erosion hazard area. Some indicators that may suggest past slope movements include: • Outwash of sediments near the bottom of the slope, • Fissures, tension cracks or naturally stepped land masses on the face or top of the slope, and parallel to the slope, • Fine,saturated subsurface soils, • Old landslide debris, • Significant bowing or leaning trees,or, • Slope sloughing or calving. The above mentioned indicators, or other signs of significant mass wasting on the property or within the general vicinity of the Project were not observed or discovered during research. Indications of past landslides, current unstable slopes, deep-seated slope problems, or surficial slope failures were not observed during the site visit. r Aerial Photo from Mason County Website Envirotech Engineering Geological Assessment PO Box 994 page 4 Parcel 32232-50-06008;09,-10 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 November 12,2020 r 3.0 SUBSURFACE INVESTIGATION Information on subsurface conditions pertaining to the project was gathered during research and a site reconnaissance. The site visit was accomplished on November 03, 2020 by a representative with Envirotech. Specific information on field methods, sampling, field testing, subsurface conditions,and results from soil testing are presented in this section of the report.Appendix B has pertinent information on subsurface conditions for the Project, including test pit log(s) representative of the site soils,and water well report(s)originating from the subject property and/ or nearby properties. 3.1 Field Methods,Sampling and Field Testing Information on subsurface conditions for the Project was accomplished by probing anticipated foundation areas with hand tools, and observing soils within test pit excavations and/ or earth cuts. Information on subsurface conditions also included reviewing geological maps within the Project vicinity,and water well reports originating from nearby properties. No soil samples were collected for this Project.Envirotech measured the relative density of the in-situ soils by gauging the resistance of hand tools. 3.2 Geologic Conditions In general, soils at the project are composed of materials from glacial advances. The geologic conditions as presented in the "Geologic Map of Washington," compiled by J. Eric Schuster, 2002 indicates Quaternary sediments, Qg. Quaternary sediments are generally unconsolidated deposits, and dominantly deposited from glacial drift,including alluvium deposits.This project is located within the Puget Lowland. Typically, "lower tertiary sedimentary rocks unconformably overlie the Crescent Formation."as revealed in the Geologic Map. Initial sedimentary rocks were formed from shales, sandstones and coal deposits from rivers. During the Quaternary period, the Puget Lowland was covered by numerous ice sheets,with the most recent being the Fraser glacier with a peak of approximately 14,000 years ago. Upon the glacial retreat, the landscape was formed by glacial erosion glacial drift deposits. The"Geologic Map of the Skokomish Valley and Union 7.5-minute Quadrangles,Mason County, Washington' by Michael Polenz, Jessica L. Czajkowski, Gabriel Legorreta Paulin, Trevor A. Conteras, Brendon A. Miller, Maria E. Martin, Timothy J. Walsh, Robert L. Logan, Robert J. Carson, Chris N. Johnson, Rian H. Skov, Shannon A. Mahan, and Cody R. Cohan, June 2010, provides the following caption(s)for the project area: Envirotech Engineering Geological Assessment PO Box 984 page 5 Parcel 32232-50-06008;09,-10 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 November 12,2020 Geologic Unit Age: Pleistocene Geologic Unit Name: Vashon Stade lodgment till Unit Description: Unsorted, unstratified(but locally banded)mix of clay, silt, sand,gravel, and sparse boulders;typically supported by a sandy matrix; mostly gray,but locally ranging to tan, light brown, or orange, typically unweathered; commonly includes clasts or clumps plucked from underlying units;clasts commonly striated and faceted,with subangular or rounded edges; compact,with well-developed facies resembling concrete, but near the surface commonly hackly and (or)looser and covered by 1 to 6 ft of loose ablation till; deposited directly by glacial ice. Large (erratic)boulders of plutonic or metamorphic(Cordilleran)rock are common on till surfaces. Some exposures include interlayers and lenses of sand and gravel, locally with shears and joints. Till commonly forms a patchy and seemingly randomly distributed cover, up to several tens of feet thick,with 5 to 20 ft most common. It typically dominates, but is also locally discontinuous on, fluted surfaces,with individual drumlins measuring 0.03 to 0.3 mi wide by 0.3 to 1.3 mi long and the long axis aligned with ice flow.Till is typically in sharp, unconformable contact with underlying units, most commonly advance outwash(unit Qga). Unit Qgt lies stratigraphically below unit Qgo. It is tempting to interpret the concrete-like properties of well-developed lodgment till as evidence for an effective aquitard. However,variable till thickness and gradational association with more permeable ice-contact deposits and outwash channels in the map area suggest that in the map area the aquitard is commonly leaky. Unit Qgt may include unrecognized exposures of older till. Age-Lithology: Pleistocene continental glacial till 3.3 Specific Subsurface Conditions The following subsurface conditions are estimated descriptions of the project subgrade utilizing information from the depth of penetration at all testing, sampling, observed and investigated locations. Soils for this project were described utilizing the Unified Soil Classification System (USCS). Using the USCS in conjunction with estimated relative densities and other anticipated engineering properties of the soil, susceptibility for potential landslides, erosion and seismic hazards may be assessed. The project is primarily composed of undisturbed, native soils, without indications of 2 feet to 3 feet of fill within one portion of the property. Competent bearing soils were encountered at 12 inches below the existing native ground surface in locations where the ground was probed. For engineering purposes,these native soils consist of distinguishable layers,as presented below. Soils within the upper 3 feet of natural ground were observed to be primarily moist, brown silty sand with gravel (SM). Soils below the upper SM layer were observed to be an SM hardpan.The hardpan is believed to extend to depths of at least 50 feet. This is based on nearby well reports, site geology, and/ or knowledge of the general area. Expanded and specific subsurface descriptions, other than what is provided in this section, are provided in the soil logs located in Appendix B of this report. According to the "Soil Survey of Mason County," by the United States Department of Agriculture, Soil Conservation Service (SCS), the site soils are described as Alderwood gravelly Envirotech Engineering Geological Assessment PO Box 994 page 6 Parcel 32232-50-06008,-09,-10 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 November 12,2020 sandy loam, k, with 15% - 30% slopes. See the soil map below, and the applicable SCS soil profile(s)in Appendix B of this report. N A 0 40 0 m Soil Survey From USDA Natural Resources Conservation Service 3.3.1 Groundwater From the water well report(s)and knowledge of the general area,permanent groundwater is at least 50 feet below the current ground surface. Surface seepage was observed on- site.Additionally,seasonal groundwater is expected to flow directly above the hardpan. Envirotech Engineering Geological Assessment PO Box 984 page 7 Parcel 32232-50-06008;09,-10 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 November 12,2020 4.0 ENGINEERING CONCLUSIONS The following sections present engineering assessments and conclusions concerning the project. These conclusions have been made available based on the planned construction activities as outlined in the Introduction Section of this report; general observations of drainage and topography as summarized in the Surface Conditions Section; and, soil conditions that were identified by the field investigation and soils testing as outlined in the Subsurface Investigation Section. Conclusions for the Project that is provided herein, includes pertinent information for landslide,erosion and seismic hazards. 4.1 Landslide Hazards For the planned development, as provided in the Introduction Section of this report, it is Envirotech's opinion that the proposed development is not subjected to or cause adverse impacts to a landslide hazard area or its associated buffer or setback as defined in the MCRO. This conclusion is based on the contents provided in this report. Landslides are natural geologic processes, and structures near slopes possess an inherent risk of adverse settlement, sliding or structural damage due to these processes.Geotechnical engineering cannot eliminate these risks for any site with sloping grades because gravity is constantly inducing strain on the sloping soil mass. Excessive wet weather and/ or earthquakes will exacerbate these strains. Geotechnical engineering considers excessive wet weather and `design' earthquakes in order to provide an acceptable factor of safety for developing on or near sloping terrain.These factors of safeties are based on engineering standards such as defining engineering properties of the soil,topography,water conditions, seismic acceleration and surcharges. Surface sloughing or other types of surficial slope movements usually do not affect the deep- seated structural capability of the slope. However, excessive and/or repeated surficial slope movements, if not repaired, may represent a threat to the structural integrity of the slope. Maintenance of the slope should be completed if the situation does arise in order to prevent the possibility of further surficial or deep seated slope movements that may be damaging to life or property. According to the Coastal Zone Atlas of Mason County, Washington, the Project is within and near terrain labeled `Stable' and `Intermediate' regarding potential landslide activity. Stable slopes are generally not prone to landslides due to small grades and accommodating geology. Historically, intermediate terrains have no known landslides. A site specific analyses and conclusions concerning the slopes are presented herein. A Stability Map from the Coastal Zone Atlas for the general area of this Project may be found below. Envirotech Engineering Geological Assessment PO Box 984 page 8 Parcel 32232-50-06008;09,-10 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 November 12,2020 ' I Hirr. Project r� G7f bind rep V stable .i " -•. t:: Intermediate t V MoVied .r.c. Z-:;J Unstable t -table(old shde) .. Lni c VVO unstable(ee[ent sbde; Map from Washington State Department of Ecology Website According to the Department of Natural Resources (DNR) "LHZ —Final A-1 Map — Landslide Inventory—Mason Watershed, by Sarikhan,et. al.,May 2007,"previous landslide activity is not recorded near the project. Per the Resource Map from DNR, the Project is not within terrain labeled `highly unstable' or `highly erodible' relating to soils. DNR labeled portions of this project as medium to high slope instability with relation to slopes. This delineation is primarily dependent upon slopes and convergence. Secondly, lithology and precipitation are modeled within this delineation. In summary, this designation is based on mapping without field observations or knowledge of the specific site geology or soils. A resource map from DNR is provided below: Envirotech Engineering Geological Assessment PO Box 984 page 9 Parcel 32232-50-06008;09;10 Belfair,Washington 99528 Mason County,Washington Ph. 360-275-9374 November 12,2020 N A Project s r _ i -- - Soils-Hydric Soils ■ . Soils-Highly Unstable Soils ' 1♦ S®-Highly Erodible Soils Westside Slope Stability Model(FP) - Moderate Slope Instability . High Slope Instability Map from Washington State Department of Natural Resources Website 4.1.1 Landslides and Slope Stability Analysis Past landslide activity or high slope instability indicators near the proposed development was not revealed during the project research. In addition,detrimental landslide activity or potential high landslide indicators were not observed during the site visit as outlined in the Surface and Subsurface Conditions Sections of this report. Due to these factors, and existing/proposed conditions,a slope stability analysis was not deemed necessary for this project. Considering the planned construction as summarized in the Introduction Section of this report; the aforementioned surface and subsurface conditions for the project; the slope stability assessment provided herein; and the Engineering Conclusions provided later in this report, it is our opinion that the project is not within a landslide hazard area, and that the proposed site alterations will not encourage a landslide hazard. 4.1.2 Surface and Subsurface Drainage This project does not appear to experience significant drainage. It is our opinion that groundwater or surface drainage is not a limiting factor for this project,but either curtain drains upslope of the residence or foundation perimeter drains should be implemented. 4.2 Erosion Hazards Based on the USCS description of the Project soils, the surface soils are considered moderately erodible. According to the Resource Map from the Washington State DNR, as provided above, the Project is not within terrain labeled `highly erodible.' This Project is within an erosion hazard Envirotech Engineering Geological Assessment PO Box 984 page 10 Parcel 32232-50-06008;09;10 Belfair,Washington 99528 Mason County,Washington Ph. 360-275-9374 November 12,2020 area as defined by the MCRO. Erosion hazard areas are those with USDA SCS designations of River Wash (Ra), Coastal Beaches (Cg), Alderwood Gravelly Sandy Loam on slopes 15% or greater (Ac and Ad), Cloquallum Silt Loam on slopes 15% or greater (Cd), Harstine Gravelly Sandy Loam on slopes 15%or greater(Hb),and Kitsap Silt Loam on slopes 15%or greater(Kc). Temporary and/or permanent erosion control measures may be required for any site when land disturbance is involved. Erosion control will mostly depend on the timeliness of construction, moisture content of the soil,and amount of rainfall during construction. Soil erosion typical to the existing conditions and planned disturbance of this Project include wind-borne silts during dry weather, and sediment transport during prolonged wet weather. Sediment transport of disturbed soils could be from stormwater runoff or tracking off-site with construction equipment. Although an engineered erosion control plan is not warranted for this project, Best Management Practices (BMP's) should be employed during and after construction. Ordinary BMP's includes silt fencing,protection of drainage outlets and vegetating denuded areas. Erosion control information and specifications may be found in the applicable "Stormwater Management Manual for Western Washington,"prepared by the Washington State Department of Ecology Water Quality Program. 43 Seismic Hazards Soils immediately below the expected foundation depth for this Project are generally Type D, corresponding to the International Building Code (IBC) soil profiles. According to the IBC, the regional seismic zone is 3 for this Project. The estimated peak ground acceleration ranges from 0.509 to 0.60g.This estimation is based on the United States Geological Survey(USGS)National Seismic Hazard Project in which there is an estimated 2% probability of exceedance within the next 50 years.There are no known faults beneath this project.The nearest Class `A' or'B' fault to this property is the Hood Canal Fault Zone. This fault is a Class V, and is located approximately 2 miles to the northwest of the Project.This information is supported by the USGS Quaternary Fault and Fold Database for the United States. The potential for liquefaction and other earthquake induced hazards are believed to be low for this project. This is based on subsurface conditions such as soil characteristics and the lack of a permanent and substantial shallow water table. Subgrade characteristics that particularly contribute to problems caused by seismic events include submerged and confined,poorly-graded granular soils. Although gravel- and silt-sized soil particles could be problematic, fine and medium grained sands are typically subjected to these types of seismic hazards. 4.4 Other Considerations Envirotech recommends that foundations should be located outside or beneath the existing fill within a portion of the property. In addition, foundations should extend to the hardpan if the development is on slopes of excess of 15%. Conclusions in this report are based on the type and location of the anticipated development, and existing on-site and off-site conditions. Site development that significantly deviates from the anticipated improvements presented in this report, or nearby development that influences this Project may require geotechnical design recommendations. Envirotech Engineering Geological Assessment PO Box 984 page 11 Parcel 32232-50-06008,-09,-10 Belfair,Washington 99529 Mason County,Washington Ph. 360-275-9374 November 12,2020 5.0 CLOSURE Based on the project information and site conditions as presented in this report, it is Envirotech's opinion that additional geotechnical studies are not required to further evaluate this project. Due to the inherent natural variations of the soil stratification and the nature of the geotechnical subsurface exploration, there is always a possibility that soil conditions encountered during construction are different than those described in this report. Therefore, it is recommended that Envirotech is promptly notified if project and subsurface conditions found on-site are not as presented in this report so that we can re-evaluate our recommendations. This report presents a geological/geotechnical assessment,and is intended only for the owner,or owners' representative. Furthermore, this report is only valid for the project information and location described herein. The services described in this report were prepared under the responsible charge of Michael Staten, a professional engineer with Envirotech. Michael Staten has appropriate education and experience in the field of geotechnical engineering in order to assess landslide hazards, earthquake hazards,and general soil mechanics. Please contact Michael Staten at 360-275-9374 if you have any questions, comments, or require additional information. Sincerely, Envirotech Engineering K. W0i;.IJr ;� Sty, Jessica Smith,M.S. Michael Staten,P.E. Staff Geologist Geotechnical Engineer Envirotech Engineering Geological Assessment PO Box 984 page 12 Parcel 32232-50-06008,-09,-10 Belfair,Washington 99528 Mason County,Washington Ph. 360-275-9374 November 12,2020 APPENDIX A SITE PLAN SCALE, 1 INCH=40 FEET 0 IO !0 PROPERTY LINE PO I OUTLINE OF r BUILDABLE AREA I 1i1 W Z / 2 TPIO co I Q I ti W I PO EAST 2ND STREET PROJECT/ OWNER/ LMATION, SINGLE FAMILY PROPERTY GEOLOGICAL ASSESSMENT ARAUJO NOTES- XXX E MAIN STREET L SLOPE INDICATORS WERE FIELD MEASURED BY ENvIROTECH,AND/OR PARCEL 32232-50-06008,-09,-10 EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE WHERE APPROPRIATE. MA Y VA 2.BOUNDARIES ON THIS SITE PLAN WERE NOT PREPARED BY A LICENSED LEGEND ENGINEER SURVEYOR.LOCATIONS OF SITE FEATURES AND GEROGICAL/ SUBSURFACE DESIGNATIONS AS SHOWN HERE.WITH RELATION TO THE PROPERTY LINES ENVIRCITECH ENGINEERING MUST BE VERIFIED BY THE OWNER. THE CONCLUSIONS AND _� $Lam AiFUATOR PO Bm(984 WODF.mAaDsx PROVIDEZ n THE a irewi 40-1 x O�x WORT BELFABR wAui YOT4v ss5m ME*03;ON aEOUM=007 YMXTI:WAMWOCE FEA744M THAT ft" P() f6tOlE 36l-8Yk-l3T'4 R OM AM LASE A 7MI r f T,, FST 74r SITE PLAN APPENDIX B SOIL INFORMATION TEST PIT LOG TEST PIT NUMBER TP-1 PROJECT: SFR Geological Assessment DATE OF LOG: 11/03/2020 PROJECT NO: 20194 LOGGED BY: RJM CLIENT. Araujo EXCAVATOR: N/A LOCATION: Parcel 32232-50-06008,-09,-10 DRILL RIG: None Mason County,Washington ELEVATION: NIA INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A SOIL STRATA. STANDARD PENETRATION TEST DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE AND TEST DATA DEPTH N 10 30 50 0 SM Brown,moist,medium dense SILTY SAND with GRAVEL Gravel Is fine and subrounded Sand is primarily coarse. Non plastic. 2 Light brown.low moisture,very dense 3 'hard n' Excavation terminated at approximately 3 0 feet a r 7 8 4 110 No Groundwater Encountered ENVIROTECH ENGINEERING This information pertains only to Cxs boring and shouts not be Geotechrncal Engineering interpreted as being indtcibve of the entire site Map Unit Description Alderwood gravelly sandy loam. 15 to 30 percent sboWs--Mason CoanN.Washington Mason County, Washington 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 transacts 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 glaclomarine deposits Typical profile A-0 to 7 inches: gravelly sandy loam Bw1-7 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 2Cd1-35 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) Interpretive groups Land capability classification(irrigated). None specified Land capability classification(nonirrigated): 4e Hydrologic Soil Group: B i` Res ources sources web Sal Survey 1 211 01201 8 Conservation Service National Cooperative Sod Survey Page 1 of 2 Map Unit Description.Atdenvood gravely sandy loam.15 to 30 percent slopes-A tason County.Washington Forage suitability group: Limited Depth Soils(G002XS301WA), Limited Depth Soils(G002XF303WA),Limited Depth Soils (G002XN302WA) Hydnic soil rating: No Minor Components Everett Percent of map unit: 5 percent Landform: Kames,eskers.moraines Landform position(two-dimensional): Backslope Landform position(three-dimensional): Side slope Down-slope shape: Convex Across-slope shape: Convex Hydric soil rating: No Indianola Percent of map unit. 5 percent Landform: Eskers,kames,terraces Landform position(three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Hydric soil rating: No Shalcar Percent of map unit: 3 percent Landform: Depressions Landform position(three-dimensional): Dip Down-slope shape: Concave Across-slope shape: Concave Hydric soil rating: Yes Norma Percent of map unit: 2 percent Landform: Depressions,drainageways Landform position(three-dimensional). Dip Down-slope shape: Concave,linear Across-slope shape: Concave Hydric soil rating: Yes Data Source Information Soil Survey Area: Mason County.Washington Survey Area Data: Version 14,Sep 10,2018 l` Natural Raaourcaa Web Sal Survey 1271012018 Conaarvation Setvice National Cooperutrve Sod Survey Page 2 of 2 CURR WATER WELL REPORT NoWt (r f' (*ems 1•..,._t.r.r.r• tttke of Ifteat Nw W 3T3R ..........O gUnique Ecology Well ID Tag No.ALN035 ndructioniDecommissioo(-x-in eimle) - MConstruction 468 Water Right Permit No.EXEMPT WELL ❑Decommission ORIGINAL INSTAII.ATIO,%, Propem Owner Name DAVIDSTF,ELF. opment Nalnbv __ _ ell Street Address 231 E LINDA VISTA COURT _ W FlIOn06[f lfaE Dwrerre IwArrrd Mwuapr _ _. - UNION e�R 103—a..a ,4y City Cotmty,MASON 7fltiO►plltil ttaaaAarmseG4a�ptersslkraeA I,Mtdlto IB IH.1;4 Ntiy�gfE Tretr, R T©emir ®t.... otirWd Mrtard:�..s 0— B- ' � t4yT La� LCM IUrgatellf LJ4J� RMSSIONS:i).c+ctwdarf rwAe.drdNd jm _ a 5ti111.t�Q'1't'1tLrlt?) �ixy.boraaeMlMs+.a �8 DefS Long!+tirv'Sex 4MMSTtLrnontl6rAua W y- Tax Parcel No, -- - c.k a n—f.r�2 a.2au .__a eI mn—jW i)—f.n f M R ('(k STMI!!1'Nf%(IR MUO"�I"ti' PIRO(.'CD1AM lre Tadrd n—f.— a 4 a MarraWe: Yes Iwo fmww.s D—be M mM,cha A.wee M n ftnd f l W.A.e.SW dr kW aad new.MMe rrwrenr.n eidi rwwery.aerwaf..Y r lod ewe ewy fo ace mw d T.y.ofpertrr«.wd ____ _ .nkwmeaw CSf.ADDITIONAL SI&I I IF NITESSARY SI71 of Pe.f. m 1.)_!..—in Mew arlrG_6ew _ A w aMATIERIAL FROM T s...+r -❑`� @+•4 xfl. lawsfa.,__v--c MNLO'M In Iff".4)AIeOOMvit. 0 16 R1.T"19D SAM AM CK4VH. to a4 - iRA1'tlAY C eI srR_._ —t l _..11■ it- tlita,,_,._'�`fblrw 6" ,MAY RILr yfiitxSt?S3IDANDtRiAYp. sl._. N'..id C.a.eeM1Teer pYr! va No QSmedOaed'esl RI"DI5111 BROWNSIL TY%ANT)AND GRAVEL 60 tt Mane.paced Ewa aro R GRAYSILTY L'IAY AND GRAVEL 64 a. UO s6r..Swl:mva Qv Towerdw&,-20' _ R BRORNSILTBOtNDSANDANDGRAVEL 110 M Mrend..dia.eJ,¢jNTQNI'IESj11M RED SILTY SAND AND GRAVEL 135 145 Illie�tavlteeeedz maatf+AYa7 1350 MI4 itilutxLTT QRA W§r laf :97 3'yprroraP o�td►drr 11MC AY ""Grifaftavoss 4MAAT1LAT f tl! VUNM►aimebrwi5+atmw IIW XL'r WJIVIQ 00WAt7 WU uS Ifo 5 Its T!"A`IClJ<l.Ri'4�t.eal.em9sw:lrssdnweba.wraaralwd _ f... r fAMatsfl�--- !iAmani aFAi ilM►, � —.ice•, I Aettakata+Arl ..—.�R+ra6lar►iedl DIMI�..-._...._.__. .�•..,-.. A oolewostawerdrl6d MifY.f�tiarit�tRaawtSrrrlw.t laaeaalaYrfs/ttarll _ _:_. '. v;eid>�ylAdf.�6.�Aae.4afRn�__k fe91:._—._AdArk6 will�,it'imMe'reAx, `Mn P.,wry deerPna.ad.wrarm rKetaa�ar�d'p N.wa6eirdrwWli trove •pa.rme.urn — _.._.__ lift W"LoOd IIWM Sfre.L.W %ft WaRIrPMi A WAMflee uas 11*— tagfwfarsr_rf a�eawr.nalee.asw+CI ft Oft ' Iea1t star atyltlT _ Csrldttalf Dti6l.�-"�.'``� _,,.__ W CUL CONSTRUCTION CERTIFICATION: I ox"wuculd an&or aaept responsibility for amuudion ofthis well.and its compliance with all Washington well oonoraction standards. Materials used=d dle infmruti.m mlxxtcd above we true to my best knowledge and bel wl: Worm.oFnl..er0T,— 400(R EDNELSf)1N _ Unllwd[<.N—yARCADIA MULLINGIWC`__ _ DniknrgwawR.tw 9grrree__ �P/�e� .VG..e PO BOX 1790 61a/a1Rrd R>•�,� a*r;��ot'_az)#,f1a1C+Utrtt`;`t ;<..dR+A.i ecva5at.latlw5w5/ The Department of Ecology does NOT warranty the Data and/or Information on this Well Report.