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HomeMy WebLinkAboutGEO2022-00069 - GEO Geological Review - 3/20/2018 ��o2o2Z-60D(o� r � s 466 � 'S� o��o O `Stye e� PLANNING Geological Assessment for Hannan Single Family Residential Property NE Tiger Mission Road Parcel No. 12305-51-00008 Mason County, Washington March 20, 2018 Project 41820 Prepared For: Patrick Hannan 1821 Winfield Avenue `�$°E sT� Bremerton, Washington 98310 — a Prepared By: Envirotech Engineering GIST 5 PO BOX 984 SsraIN,ALtirG Belfair, Washington 98528 Phone: 360-275-9374 Mason County Department of Community Development Submittal Checklist For a Geological Assessment Instructions: This checklist must be submitted with a Geological Assessment and completed, signed, and stamped by the licensed professional(s)who prepared the Geological Assessment for review by Mason County pursuant to the Mason County Resource Ordinance. If an item found to be not applicable, the report should explain the basis for the conclusion. Applicant/Owner Patrick Hannan Parcel# 12305-51-00008 Site Address XXX NE Tiger Mission Road, Mason County (1) A discussion of geologic conditions in the general vicinity of the proposed development,with geologic unit designation based on referenced maps. Located on page(s) 5 (2) (a)A discussion of the ground water conditions at the site, Located on page(s) 7 (b) A discussion of the estimated depth to water Located on page(s) 7 (c) A discussion of the quantity of surface seepage Located on page(S) 7 (d) A discussion of the upslope geomorphology Located on page(s) 3 (e) A discussion of location of upland waterbodies and wetlands. Located on page($) 3 (3) The approximate depth to hard or dense competent soil, e.g. glacial till or outwash sand. Located on page(s) 6 (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. Page 1 of 2 Form Effective June 2008 Located on page(s) 12 (8) If the presence of a hazard is determined within 300 feet of the proposed development, then the following are delineated on a geologic map/site map: (a) the area of the 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, bath 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(app.A) I, Michael C. 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 March 20, 2018 and entitled Hannan Single Family Residential Property meets all the requirements of the Mason County Resource Ordinance, Landslide Hazard 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. (Signature and Stamp) \��C L1 pE S � a � 120/18 Disclaimer: Mason County doe s not certify the quality of the work done in this Geological � Assessment. Page 2 of 2 Form Effective June 2008 TABLE OF CONTENTS 1.0 INTRODUCTION.................................................................................................................................I 1.1 PROJECT INFORIMATION..................................................................................................................... 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.....................................................................................9 4.1.2 Surface and Subsurface Drainage........................................................................................... 10 4.2 EROSION HAZARDS...........................................................................................................................10 4.3 SEISMIC HAZARDS............................................................................................................................10 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 along NE Tiger Mission Road, identified as parcel number 12305-51- 00008 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 February 12, 2018. 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 support of the soils to 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: • 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; • 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,PLLC Hannan Geological Assessment PO Box 984 page 1 Parcel 12305-51-00008 Belfair,Washington 98528 Mason County;Washington (360)275-9374 March 20,2018 y r Nf Live,F7 N.`_Cal}'_- It tFr L.A.. C =� Project s.=r cfe y x ' K ' Vicinity Map from Mason County Website Envirotech Engineering,PLLC Hannan Geological Assessment PO Box 984 pale 2 Parcel 12305-51-00008 Belfair,Washington 98528 Mason County,Washington (360)275-9374 March 20,2018 2.0 SURFACE CONDITIONS Information pertaining to the existing surface conditions for the project was gathered on February 12,2018 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 an existing ingress/ egress. Tiger Mission Road extends along the east side of the property, and Tiger Cove Lane is located immediately to the west. Vegetation on and near the property consists primarily of firs, cedars, 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. Maximum slope grades are approximately 38%with a vertical relief of approximately 20 feet. 2.2.1 Upslope Geomorphology Ascending grades are generally located to the east of the planned development. This slope is relatively minor within 300 feet of the Project, with no apparent slope grades of at least 15%. 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 minimal. Significant scour, erosion and sediment transport was not apparent near the project. 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,PLLC Hannan Geological Assessment PO Box 984 page 3 Parcel 12305-51-00008 Belfair,Washington 98528 Mason County,Washington (360)275-9374 March 20.2018 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. MP Y'Is v�t 3 i MT 7 �i,{' ..p �-�� •Y � -sue ,yt.�a� f , 3 r- it`�is�3 y` s �J�14 � .. xRY�Sa�`3'�..F?d T_.�,r+•�4 �f...�;3.ti�-�'"-rWe�ic�..� Aerial Photo from Mason County Website Envirotech Engineering,PLLC Hannan Geological Assessment PO Box 984 page 4 Parcel 12305-51-00008 Belfair, Washington 98528 Mason County,Washington (360)275-9374 March 20,2018 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 March 3, 2018 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, Q8. 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. fir' �,• '` cu QVt �o �0)a oD Envirotech Engineering,PLLC Hannan Geological Assessment PO Box 984 page 5 Parcel 12305-51-00008 Belfair,Washington 98528 Mason County,Washington (360)275-9374 March 20,2018 17ashon till—Unsorted.unstratified(but locally banded)nix of clay. silt. sand.and gravel: typically supported by a sandy matrix,mostly gray but locally ranging to tan.light brmvn. or orange:typically unixeathered: lodgment till compact.with well-developed facies resembling concrete, but near the suuface commonly hnackly and(or)looser and covered by 1 to 6 ft of loose ablation till:deposited directly by glacial ice and commonly includes clasts or chunps plucked fi•om underlying units. C'lasts are conlnnonly striated and faceted,with angular or rounded edges. Boulders are generally sparse within the till but large (erratic)boulders of plutonic or nnetamoiphic rock are comnnon on till surfaces, Some exposures include interbands and lenses of sand and gravel,locally with shears and joints. Till forms a locally patchy and seemingly randomly distributed cover tip to a several tens of feet thick.with a thickness of 5 to 20 ft most common.It typically dominates.but is also locally discontinuous oil. fluted surfaces. with individual dnurrlins measw-ing 0.1 to 0.3 mi wide by 0.3 to 1.3 mi long and the long axis aligned with the direction of ice flow.Till typically is in sharp.unconfolmible contact with underlying units.most commonly advance ouNvash(unit Qga and submit). Unit Qgt lies stratigraphically below unit Qgo. It may include un recognized exposures of older till.A map boundary mismatch bem-een unit Qgt our this neap and uutit Qgos on the Vauglun quadrangle to the south(Login and"Walsh. 2007)may have resulted from a map-production error in the northwest corner of the 'Vaughn map(Josh Logan.Wash. Div n. of Geology and Earth Resources. oral connmun., 2009). 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 substantial fill. 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 4 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,PLLC Hannan Geological Assessment PO Box 984 page 6 Parcel 12305-51-00008 Belfair,Washing ton 98528 Mason County,Washington (360)275-9374 March 20,2018 0 o sandy loam, Ab, with 8/o - 15/o slopes. Steeper slopes were mapped on the property, but not where development is expected to occur. See the soil map below, and the applicable SCS soil profile(s)in Appendix B of this report. YCf.` K r 4 J ' all At 7A e L aF ' d = IV .. i 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 or perched groundwater at shallow depths was not observed on-site, nor indicated on the well reports. However, some seasonal groundwater is expected to flow directly above the hardpan on occasion. Envirotech Engineering,PLLC Hannan Geological Assessment PO Box 984 page 7 Parcel 12305-51-00008 Belfair,Washington 98528 Mason County,Washington (360)275-9374 March 20,2018 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 J P , p 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 of the soil topography,water conditions seismic properties 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 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,PLLC Hannan Geological Assessment PO Box 984 page 8 Parcel 12305-51-00008 Belfair,Washington 98528 Mason County,Washington (360)275-9374 March 20,2018 t4 FI 1J � Tea` F� S Tatter t A4; -� f �r Project f ri 1646 �'StB�3R 74 E6ff1° ,js'.' lt. .� in 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. Envirotech Engineering,PLLC Hannan Geological Assessment PO Box 984 page 9 Parcel 12305-51-00008 Belfair,Washington 98528 Mason County,Washington (360)275-9374 March 20,2018 4.1.2 Surface and Subsurface Drainage This project does not appear to experience significant subsurface drainage or surface runoff. It is our opinion that groundwater or surface drainage is not a limiting factor for this Project. 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 not within an erosion hazard 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), Cloqualium 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. 4.3 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 0.50g 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 Tacoma Fault Zone. This fault is a Class `A,` and is located approximately 8 miles to the south 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 Envirotech Engineering,PLLC Hannan Geological Assessment PO Box 984 page 10 Parcel 12305-51-00008 Belfair,Washington 98528 Mason County,Washington (360)275-9374 March 20,2018 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 We recommend roof and driveway dispersion for this project, such as allowing stormwater to sheet flow across vegetation. 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,PLLC Hannan Geological Assessment PO Box 984 page 11 Parcel 12305-51-00008 Belfair,Washington 98528 Mason County,Washington (360)275-9374 March 20,2018 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 Michael Staten,P.E. Geotechnical Engineer Envirotech Engineering,PLLC Hannan Geological Assessment PO Box 984 page 12 Parcel 12305-51-00008 Belfair,Washington 98528 Mason County,Washington (360)275-9374 March 20,2018 APPENDIX A SITE PLAN A SCALE, 1 INCH = 100 FEET 0 2550 — 100 053 j�e TP1 / PO / 600 r i PQ r J / 4 I Po r n 1 r 530 S U S 0 5 0 S U 5� ALLOWABLE BUILDING ENVELOPE FOR BUILDINGS AND SEPTIC PROJECT/ OWNER/ LOCATIONt SINGLE FAMILY PROPERTY GEOLOGICAL ASSESSMENT HANNAN NOTES- XXX NE TIGER MISSION ROAD L SLOPE INDICATORS WERE FIELD MEASURED BY ENVIROTECH, AND/ OR PARCEL 12305-51-00008 EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE WHERE APPROPRIATE. --- MASON COUNTY WASHINGTON 2. BOUNDARIES ON THIS SITE PLAN WERE NOT PREPARED BY A LICENSED LEGEND ENGINEER SURVEYOR. LOCATIONS OF SITE FEATURES AND GEOLOGICAL/ SUBSURFACE ENVIROTECH ENGINEERING DESIGNATIONS AS SHOWN HERE, WITH RELATION TO THE PROPERTY LINES MUST BE VERIFIED BY THE OWNER, THE CONCLUSIONS AND — SLOPE INDICATOR PO BOX 984 RECOMMENDATIONS PROVIDED IN THE GEOTECHNICAL/ GEOLOGICAL REPORT BELFAIR, WASHINGTON 98528 ARE BASED ON GEOLOGIC AND SPECIFIC SUBSURFACE FEATURES THAT MAY PO PROBE 360-275-9374 BE LOCATED ON AND OFF THE PROPERTY, AND ARE NOT NECESSARILY BASED OFF OF PROPERTY LINES SHOWN ON THIS SITE PLAN, TP11@ TEST PIT SITE PLAN APPENDIX B SOIL INFORMATION TEST PIT LOG TEST PIT NUMBER TP-1 PROJECT: Hannan Geotechnical Report DATE OF LOG: 2/12/2018 PROJECT NO: 1820 LOGGED BY: MCS CLIENT: Patrick Hannan EXCAVATOR: NIA LOCATION: Parcel 12305-51-00008 DRILL RIG: None Mason County, Washington ELEVATION: N/A 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, loose to medium dense SILTY SAND with GRAVEL. Gravel is .' primarily well-graded and subangular. Sand is mostly medium, Low plasticity. 2 P 3 4 Excavation terminated at approximately 4.0 feet 5 6 7 8 9 10 No Groundwater Encountered ENVIROTECH ENGINEERING This information pertains only to this boring and should not be Geotech nical Engineering interpreted as being indicitive of the entire site. Map Unit Description:Alderwood gravelly sandy loam,15 to 30 percent slopes--Mason County,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 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 glaclomarine 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) Interpretive groups Land capability classification(irrigated): None specified Land capability classification (nonirrigated): 4e Hydrologic Soil Group: B usDA Natural Resources Web Soil Survey 3/19/2018 �e Conservation Service National cooperative Soil Survey Page 1 of 2 WATER WELL REPORT CURRENT Original&1"copy-Ecology,2"copy—owner,Yl copy-driller Notice of intent No.WE21967 a CPARTMCr:el ECOLOGY Construction/Decommission("x"in circle) Unique Ecology Well ID Tag No.ALH 669 CL ® Construction Water Right Permit No. ( j ❑ Decommission ORIGINAL INSTALLATION ! Notice o Intent Number Property OwncrName Al Williams PROPOSED USE: 0 Domestic ❑ Industrial ❑ Municipal Well Street Address 521 NE Tiger-Mission Rd ❑ DeWater ❑ irrigation ❑ Test well ❑ Other City Be fair County Mason ri'PE OF WORK: Owner's number of well(irmore than one) Location SW I/4 1/4 NEl/4 Sec 5 Twn 23N R 1 EWM El© New well ❑ Reconditioned ldethnd:❑ Due, ❑ Bored ❑ Driven❑ Deepened ® Cable ❑ Rotary ❑ Jetted (s,t,r Still REQUIRED) Or DIMENSIONS: Diameter inches,drilled WWM � Lat/l,ong Depth orcom letcd we11163 A- Lai Deg Lat Min/See CONSTRUC 11ON DETAiLS Long Deg Long Min/Sec Casing ® Welded 6" Diam.from+1 A.to 157 A, Installed: ❑ Linerinstalted Diam.from A,to ft. Tax parcel No.(Required)12305139DOb0 Threaded Diam.From A.to A. Perforations: ❑ Yes N No CONSTRUCTION OR DECOMMISSION PROCEDURE L` Type of perforator used Formation:Describe by color,character,size ofmaterial and structure, and the kind and nature of the material in each stratum penetrated,with at SIZE efpens_in.by_in.and no,of perfs„from_A,to A. least one entry for each change of information. (USE ADDrrIONAL Screens:-® Yes ❑ No ® K-Pac Location 155' SHEETS IF NECESSARY. Manufacturcr'sName Machine Alloy Works MATERIAL FROM TO Type stainless Model No. Topsoil 0 2 }-� Diam.5SIot size 20 from 158 A.to 163 A. ' Brown till 2 66 Diam. Slot size from A.to A. Brown till w/water 66 101 Gravel/Pilfer packed: ❑ Yes ® No Size of gtavcl/sand Brown till 101 145 Materials placed from A.to A. Sand&gravel w/water 145 163 Surface Seal• ® Yes ❑ No To what depth?28A. Material used in seal betonite - Did any strata contain unusable water?. ., Cl Yei ® N6' A t Dcpth of itraia Type of Tratc(? Method of scaling strata off - PU,A9P: Manufacturer's Name Goulds -- •Type:sub sub - - H.P. I WATER LEVELS: Land-surface elevation above mean sea level A. t #� Static level 145 A.below top of well Date Artesian pmssurc lbs.per square inch Date Artesian water is controlled b• (cap,valve,etc. WELL TESTS:DraTvdown is amount water level is lowered below static level •rr n�'` Was a pump test made? ❑ Yes ® No If yes,by whom? Yield: galJtnin,with A.drawdown after hTs. Yield; galJmin.with ft.drawdown after his. Z Yield;__­.got-Anin-with A.drawdown after hrs. t Recovery dots(time taken a.,•tern when pump[tinted aft)(water level measured from well top in wafer level) Time Water Level Time Water Level Time . Water Level `- _� c Date of test t1f Bailer lest 10 galJmin-with 2 ft.drawdown anei 1 hrs. of Ecclioa" 13 Airiest galJmin.with stem set at A.for hrs. Artesian now g.p.m.Date— • _ l Temrienturc of umler .- Was a chemical analysis made? 0 Yes No Start Date 9/28/15 Completed Date t10115/15 WELL CONSTRUCTION CERTIFICATION: 1 constructed and/or accept responsibility for constriction of this well,and its compliance'with all Washington well "construclion standards..Materials used and the information reported above are true to raj best latowledge and belief.- ®Driller❑Engineer❑Traincc Name(Print)Emily Davis Drilling Company Davis Drilling t' Driller/Eneincerlfrainee Signature Address 340 NE Davis Farm Rd Driller or trainee License N0.3142 Ciryt State,Zip Belfair WA, 98528 1F TRAINEE;Drillcr's Liccnsc No: Contractor's Driller's Signature_ Registration No. DAVISDI1100A Date October 2015 ECY OSO-1-20(Rev 02-2010) To regnesr ADA accommodation including materials in a format far the visrially impaired,calt Ecology Water Resources Program at 360-407-6872. Persons with unpaired Itearing may call Washington Relay Service of 711. Persons lvitit speech disability may call 7TY at 877-833-6341. EVI,V'roteC,h EvLO'v,eerbv1,O, PLLc. ceotechwicat� Ewv�roww,,ewtat �Dratwage�Fzoadwa� December 24,2021 Patrick Hannan 1821 Winfield Avenue Bremerton,Washington 98310 Reference: Geotechnical Evaluation for Tree Removal XXX NE Tiger Mission Road(Parcel 12305-51-00008),Belfair,Washington Dear Mr.Hannan, Envirotech Engineering,PLLC has completed a recent site assessment of the referenced property.The site visit was conducted by Envirotech on December 15, 2021 in order to evaluate tree.removal on the property.Envirotech previously completed a geological assessment for the property on March 20, 2018. The critical slopes on the property have grades of just under 40%. The County Code for view corridors requires a geotechnical assessment for cutting trees on slopes that are larger than 6 inches in breast-height diameter. It is our opinion that cutting trees per County Code for viewing purposes is acceptable, and that cutting trees with a breast height of 6 inches or more will not create unsatisfactory slope stability issues. Thank you for the opportunity to work on this project. If you have any questions or need any further assistance,please contact Michael Staten at 360-275-9374. Sincerely, Envirotech Engineering CLY DE ST ?t�C SO4R�O r 'ONAL E�G1 12/24/21 Michael Staten,P.E. Project Director Po gox904 getfatr, W6I.SK ,gtow9052g D f f: 360-2'-5-9374 Cell.: 360-009-6045 ewvtrotech@geotechwtcali.w fo.coK& 1_V12 MM!0a01 lvl,a6sems-Geological Assessment Review C,h-eckli-s.t6.-OI8.doc--.----.------.--.----.--- Page-!,,I Mason County Review Checklist For a Geological Assessment Instructions: This checklist is intended to assist Staff in the review of a Geological Assessment. The Assessment is reviewed for completeness with respect to the Resource Ordinance. If an item is found to be not applicable,the report should explain the basis for the conclusion.The Assessment is also reviewed for clarity and consistency. If the drawings,discussion,or recommendations are not understandable,they should be clarified. If they do not appear internally consistent or consistent with the application or observations on site,this needs to be corrected or explained. If resolution is not achieved with the author,staff should refer the case to the Planning Manager or Director. Applicant's Name: PVjA,4), NAYk Y\C,Y\ Permit# FPA 2 Z - I —Parcel#- R-30S - 5- 1 - COCO? Date(s)of the Document(s)reviewed: W/ i I) (1) A discussion of geologic conditions in the general vicinity of the proposed development,with geologic unit designation based on referenced maps. OK? / Comment: (2) (a)A discussion of the ground water conditions at the site, OK? V' Comment: (b) A discussion of the estimated depth to water OK? Comment: (c) A discussion of the quantity of surface seepage OK? Comment: (d) A discussion of the upslope geomorphology OK? V Comment: q, 2- 1 (e) A discussion of location of upland waterbodies and wetlands. OK? V Comment: � , 3, 1 (3) The approximate depth to hard or de cpetent soil, e.g.glacial till or outwash sand. OK?__i/—Comment: 7 om (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.). OK?__V Comment: 3, (,) (5) A discussion of the history of landslide activity in the vicinity,as available in the referenced maps and ecords. OK? V Comment: (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 proposedL51evelopment. OK? Comment: (7) A recommendation by the preparer whether a Geotechnical Report should be required to further evaluate site conditions and the P posed development of the subject property. OK? I/ Comment: ? 0 (8) If the presence of a hazard is determined within 300 feet of the proposed development, then the following are delineated on a geologic map/site map: (a) the area of the proposed development, OK? Comment: A- (b) the boundaries of the landslide hazard area(top, both sides, and toe), Page 1 of 2 Form Effective June 2008 (6712/2008) Michael-Ma cSems Geological Assessment Review Checklist 6 08.doc Page 2, OK? Comment: N A (c) the associated buffers(top,both sides, and toe) OK? Comment: 'L/ A (d) building or other setbacks(top, both sides,and toe). OK? Comment: /V / (9) A site map drawn to scale showing the property boundaries,scale, north arrow,and the location and nature of existing and propo ed development on the site. OK? ✓ Comment: 1 Are the Document(s)signed and stamped? Type and#of License: NW f1��I V1ee� 11 y 3 �4� If not approved,what is the next action/recommendation for further action? ®Cow y� � Reviewed by ��� ,on Time spent in review: SECOND REVIEW/UPDATE: Reviewed by on Time spent in second review: THIRD REVIEW/UPDATE: i Reviewed by on Time spent in third review: Disclaimer: Mason County does not certify the quality of the work done in this Geological Assessment Page 2 of 2 Form Effective June 2008 G�a2z - G �n�fi Mason County Department of community Development Submittal Checklist For a Geolo ical Assessment instructions: This checklist must be s b ofessi nmitted 'ah(s)who prepared ed the Geological Ass a Geological Assessment and essmentt for drev review by stamped by the P Mason County pursuant to the Mason County Resource Ordinance. If an item found to be no applicable, the report should explain the basis for the conclusion. Applicant/Owner Patrick Hannan Parcel# 12305-51-00008 Site Address XXX NE Tiger Mission Road, Mason County (1) A discussion of 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 the ground water conditions at the site, Located on page(S) 7 (b) A discussion of the estimated depth to water Located on page(S) 7 (c) A discussion of the quantity of surface seepage Located on page(S) 7 (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($) 3 (3) The approximate depth to hard or dense competent soil, e.g. glacial till or outwash sand. Located on page(S) 6 (4) A discussion of any geomorphic expression of past slope instability(presence of hummocky ground indicatings movemelve of nt, etc.)landslide block movement, bowed or arched trees downiope 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 (g) its associated buffer or An opinion on whether the setback and the potential for landslide activity at t e site in light de hazard area of the proposed development. p P Located on page(s) 8 e preparer whether a Geotechnical Report should be ired (7) A recommendation by thditions and the proposed development of he subject property.to further evaluate site con Form Effective June 2008 Page 1 of 2 Located on page(s) 12 (8) If the presence of a hazard is determined within 300 feet of the proposed development, then the following are delineated on a geologic map/site map: (a) the area of the 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(app.A) I, Michael C. 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 March 20, 2018 , and entitled Hannan Single Family Residential Property meets all the requirements of the Mason County Resource Ordinance, Landslide Hazard 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. (Signature and Stamp) ST ' \ 43045 V Ff,�f�JIS ii:R�� \.lam /20/18 Disclaimer: Mason County does not certify the quality of the work done in this Geological Assessment. Page 2 of 2 Form Effective June 2008