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Home My WebLink AboutGEO2018-0003 for BLD2017-01103 - GEO Geological Review - 12/21/2017 • R a✓b 2/-)i8 -= )) RECEIVED �9I2 I C 2.6 1 -7 — I I D JAN 0 8 2N 615 W. Alder Street Geological Assessment for Shearer Logging & Single Family Residential Property 401 NE Timberline Drive Parcel No. 12320-34-00030 Mason County, Washington December 21, 2017 Project#17195 Prepared For: Tom Shearer PO Box 1959 �P�` CL °�sT9 Belfair, Washington 98528 Prepared By: Envirotech Engineering �o ,��a 3O45��oG`�ww4 PO Box 984 NALE� Belfair, Washington 98528 Phone: 360-275-9374 I 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 Tom Shearer Parcel# 12320-34-00030 Site Address 401 NE Timberline Drive, Belfair (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(s) 4 (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($) 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) 9 (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) 9 (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, 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 Dec. 21, 2017 , and entitled Shearer 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) PEL CLYDt ST P 8 9G� 43045�`�� l N�lr,VAl r� ` 12/21/17 Disclaimer: Mason County does 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.................................................................................................................................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..................................................................................................................4 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 3.4 SOILS TESTING AND PROPERTIES......................................................................................................7 3.4.1 INFILTRATION RATES......................................................................................................................8 4.0 ENGINEERING CONCLUSIONS......................................................................................................9 4.1 LANDSLIDE HAZARDS.........................................................................................................................9 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 (Envirotech) has completed this geological assessment for a residential property located at 401 NE Timberline Drive, identified as parcel number 12320-34-00030 in Mason County, Washington (Project). 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 September 12, 2016. 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 property owner, and observations from a field visit by Envirotech. The proposed development is expected to consist of a new single family residence, driveway and other ancillary features typical of this type of development. Approximate site development with relation to existing site features are illustrated in the Site Map in Appendix A. 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: • Review project information provided by the Project owner's representative; • 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 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 Project. Envirotech Engineering Shearer Geological Assessment Ph.360-275-9374 page I Parcel 12320-34-00030 Fax: 360-275-4789 Mason County,Washington December 21,2017 1 I i I Vicinity Map from Mason County Website Envirotech Engineering Shearer Geological Assessment Ph.360-275-9374 page 2 Parcel 12320-34-00030 Fax:360-2754789 Mason County,Washington December 21,2017 2.0 SURFACE CONDITIONS Information pertaining to the existing surface conditions for the Project was gathered on September 12, 2017 and December 12, 2017 by representatives 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 Project is currently vacant land with few improvements such as a road. Clearing and light grading is apparent.This includes past logging and stumping. The property is surrounded by rural residential development. Timberline Drive extends along the north side of the property, and the Union River and other water features on the south portion of the property.Vegetation on and near the property consists primarily of 2°d growth firs, alders, 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 Map 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 up to approximately 23%with a vertical relief of approximately 15 feet. Some steeper slopes were observed,but negligible vertical height and influence on the project. 2.2.1 Upslope Geomorphology Ascending grades are generally located to the northwest 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 gentle hillside. Landforms are primarily of glacial origin with centuries of weathering overburden. Most of the property consists of alluvium. 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 to moderate. Significant scour, erosion and sediment transport was not apparent near the planned development. The Union River, stream and wetland on the property have drainage issues,and is distant from the proposed project. Envirotech Engineering Shearer Geological Assessment Ph.360-275-9374 page 3 Parcel 12320-34-00030 Fax:360-2754789 Mason County,Washington December 21,2017 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. 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. Except for streambank erosion in the Union River, 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. Tk s 37YD�9 A � lot . 41 ' � PAL Ot Z.+ .ya: , I a _ !IIf IIIM lI-IIII I t. .a Aerial Photo from Mason County Website Envirotech Engineering Shearer Geological Assessment Ph.360-275-9374 page 4 Parcel 12320-34-00030 Fax:360-2754789 Mason County,Washington December 21,2017 3.0 SUBSURFACE INVESTIGATION Information on subsurface conditions pertaining to the Project was gathered during research and a site reconnaissance. The site visits were accomplished on September 12, 2016 and December 12, 2017 by representatives 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, Qx. 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 Belfair 7.5-minute Quadrangle, Mason, Kitsap and Pierce Counties, Washington" by Michael Polenz, Katelin Alldritt, Nicholas J. Hehemann, Isablle Y. Sarikhan, and Robert L. Logan,July 2009,provides the following caption(s)for the project area: Envirotech Engineering Shearer Geological Assessment Ph. 360-275-9374 page 5 Parcel 12320-34-00030 Fax: 360-275-4789 Mason County,Washington December 21,2017 Alluvium—Silt.sand.and gravel:clasts typically well rotwded:typically well sorted and loose:stratified to massively bedded:deposited in streams and adjacent banks The sediment source is most conunonly reworked recessional outwash.ablation till.advance outs;•ash.and(or) glaciolacuustrine deposits.but may include lodgment till.nonglaclal deposits.and bedrock.Exposures locally resemble the units sediment source units,a particularly notable feature in the Union River valley. where the unit is mostly derived from glaciolacustrine and(or)ice-contact deposits(units Qgof and Qgic).Shear-wave velocity profiles confirm. however.that unit Qa forums a more diverse deposit than unit Qgof and at least some deposits of unit Qgic(Fig.4). Subunit Qoa is older alluvium that resembles unit Qa in every way but forms elevated.relict terraces. Most appear to be tied to an elevated base level that prevailed prior to a local base-level lowering event(s)(see discussion of elevated terraces under Structure).Where unfit Qoa is correctly identified along the lower reaches of streams that are graded to sea level,the age of unit Qoa should not exceed about 6,000 years because prior to that.sea level was sieunficantly lower.which likely resulted in an erosional setting that precluded deposition of alluvium.As mapped,the unit is generally Holocene but may locally include some unrecognized recessional outwash terraces(unit Qgo)and other late Pleistocene deposits.A map boundary misnLitch with the Vaughn quadrangle to the south resulted where Logan and Walsh(2007)humped unit Qoa into unit Qa.Elsewhere.the contact between unit Qa(this map)and units Qgt and Qaf(Vaughn quadrangle) nuns so close to the map boundary that map scale did not permit separating the geologic boundaries from the map boundary. 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. However, some fill could be present. Competent bearing soils were encountered at 18 inches below the existing 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 6 feet of natural ground were observed to be primarily moist, brown silty sand with gravel (SM). Soils below the upper SM layer could be a conglomerate of sand, silt and clay. 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 USDA Textural Classification System, the site soils are primarily classified as sandy loam. Some pockets of gravelly soils was also observed. Soil structure may be described as granular. Envirotech Engineering Shearer Geological Assessment Ph. 360-275-9374 page 6 Parcel 12320-34-00030 Fax: 360-275-4789 Mason County,Washington December 21,2017 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 Everett gravelly loamy sand, with 5% - 15% slopes, Belfast silt loam, with 0 — 3% slopes, and Indianola loamy sand, with 5% to 15% slopes. See the soil map below, and the applicable SCS soil profile(s) in Appendix B of this report. �x f� • 9 - , �` �._� �, , •�'� Y w " t� � -per Aw Y. y r ,s't � r' .t r ► .v. C 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 directly below the property at the building pad location. Surface seepage or perched groundwater at shallow depths was not observed on-site, nor indicated on the well reports. 3.4 Soils Testing and Properties The soil samples obtained at the Project site during the field investigation were preserved and transported for possible laboratory testing. Visual classification of soils was performed in the field at all observed soil profiles. Visual classifications were performed in accordance with the American Standards for Testing and Materials(ASTM D2488). The general results from the visual classification are presented above in the Subsurface Conditions Section. Specifically, soils within the upper 4 feet in one testing location consisted of Envirotech Engineering Shearer Geological Assessment Ph. 360-275-9374 page 7 Parcel 12320-34-00030 Fax: 360-2754789 Mason County, Washington December 21,2017 approximately 12% gravel, 55% sand-sized soils, and 33% fines with no plasticity indicating a very low content of clay within the fine fraction. Minor variations observed during the visual classification of particle size content (i.e. gravel, sand, fines), or isolated pockets within the soil stratification were insignificant in relation to the overall engineering properties of the soil. Based on the fines content, erodibility of the site soils is considered to be moderate. However, soils on disturbed slopes are more apt to erode than disturbed soils on flat ground. Based on the fines content and fraction of clay within the fines content, settleability of the site soils is expected to be moderate to fast. Permeability is expected to be high for this site due significance of moderate density,poorly graded granular soils. 3.4.1 Infiltration Rates According to the 2005 Stormwater Management Manual for Western Washington prepared by the Washington State Department of Ecology Water Quality Program, infiltration rates are determined per the USDA Textural Classification of the soils,and an appropriate factor of safety. Based on the soils consisting predominantly of sandy loam, and utilizing a factor of safety of 2, site infiltration for stormwater facilities should be 0.33 inches/hour. 3.4.2 Cation Exchange Rate Water quality for this project is achieved by the soil subgrade beneath the sub-base water storage area. The Cation-Exchange Capacity (CEC)of the soils, based on soil texture and testing as provided above, the CEC ranges from a minimum of 15 to 40 meq/100g. Based on the abundance of organic matter in the top soil,the CEC values may be much higher. Envirotech Engineering Shearer Geological Assessment Ph. 360-275-9374 page 8 Parcel 12320-34-00030 Fax: 360-275-4789 Mason County,Washington December 21,2017 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 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 did not label portions of this project as medium to high slope instability with relation to slopes. A resource map from DNR is provided below: Envirotech Engineering Shearer Geological Assessment Ph. 360-275-9374 page 9 Parcel 12320-34-00030 Fax: 360-275-4789 Mason County,Washington December 21,2017 1,N ,�+ r Project � � ' °•� it • 16oss . I y 'r 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 appear to experience hydric soils and significant surface runoff on the south portion of the property. It is our opinion that groundwater or surface drainage is not a limiting factor for this Project where development is expected to occur due to the elevation difference. However, finish floors should be above flood levels. 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 ---------------------------------- — Envirotech Engineering Shearer Geological Assessment Ph.360-275-9374 page 10 Parcel 12320-34-00030 Fax:360-275-4789 Mason County,Washington December 21,2017 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), 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). Due to the type and magnitude of development, full erosion control plans are required for this project. Temporary and permanent erosion control measures are required for site development, and shall be provided in a stormwater management plan. 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 5 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. According to the Interactive Geologic Map of Washington, liquefaction susceptibility is very low within the vicinity of this project. This is also 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 Logging and Other Considerations The past logging does not appear to be detrimental to nearby moderate slopes. 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 Shearer Geological Assessment Ph. 360-275-9374 page l l Parcel 12320-34-00030 Fax: 360-275-4789 Mason County, Washington December 21,2017 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 Shearer Geological Assessment Ph. 360-275-9374 page 12 Parcel12320-34-00030 Fax: 360-275-4789 Mason County,Washington December 21,2017 I�I APPENDIX A SITE PLAN SCALE, 1 INCH 150 FEET PROPOSED 12' VIDE DRIVEWAY \ 60 WELL \ LOGGED • 1 SEPTIC FAMD_ DRAT F P o SI 1 1 Po + LOGGED rr \ RIVER/ WETLAND LOGGED� BUFFER / CATEGORY II WETLAND PROJECT/ OWNER/ LOCATION- SINGLE FAMILY PROPERTY GEOLOGICAL ASSESSMENT TOM SHEARER TIMBERLINE DRIVE PARCEL 12320-34-00030 MASON COUNTY WASHINGTON LEGEND ENGINEER, ENVIROTECH ENGINEERING PO —� SLOPE INDICATOR BOX 984 BELFAIR, WASHINGTON 98528 PO PROBE 360-275-9374 TPI@ TEST PIL____J, SITE PLAN APPENDIX B SOIL INFORMATION TEST PIT LOG TEST PIT NUMBER TP-1 PROJECT: SFR Geological Assessment DATE OF LOG: 09/12/2016 PROJECT NO: 17195 LOGGED BY: RM CLIENT: Tom Shearer EXCAVATOR: N/A LOCATION: Parcel 12320-34-00030 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 p ....................... SM Brown, moist, medium dense SILTY SAND with trace of gravel. Gravel is fine _ and subrounded. Sand is primarily 1 medium. Non plastic. 2 3 Excavation terminated at approximately 3.0 feet 4 5 6 7 8 9 110 No Groundwater Encountered ENVIROTECH ENGINEERING This information pertains only to this boring and should not be Geotechnical Engineering interpreted as being indicitive of the entire site. I TEST PIT LOG TEST PIT NUMBER TP-2 PROJECT: SFR Geological Assessment DATE OF LOG: 12/12/2017 PROJECT NO: 17195 LOGGED BY: MCS CLIENT: Tom Shearer EXCAVATOR: N/A LOCATION: Parcel 12320-34-00030 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 - ... . ... .. .... .. . I .. .. . . .. ... . . SM Brown, moist, medium dense SILTY SAND with trace of gravel. Gravel is fine _ and subrounded. Sand is primarily 1 medium. Non plastic. 2 3 Increasing gravel 4 5 6 Excavation plus probe terminated at approximately 6.0 feet 7 8 9 110 No Groundwater Encountered ENVIROTECH ENGINEERING This information pertains only to this boring and should not be Geotechnical Engineering interpreted as being indicitive of the entire site. Map Unit Description:Belfast silt loam,0 to 3 percent slopes—Mason County,Washington Mason County, Washington Bb—Belfast silt loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 2hjg Elevation: 20 to 600 feet Mean annual precipitation: 50 to 70 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 160 to 180 days Farmland classification: All areas are prime farmland Map Unit Composition Belfast and similar soils: 100 percent Estimates are based on observations, descriptions, and transacts of the mapunit. Description of Belfast Setting Landform: Flood plains Parent material: Alluvium with volcanic ash Typical profile H1 -0 to 11 inches: ashy silt loam H2- 11 to 25 inches: silt loam H3-25 to 60 inches: stratified loamy sand to silt loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Capacity of the most limiting layer to transmit water(Ksat): Moderately high to high (0.57 to 1.98 in/hr) Depth to water table: About 19 to 72 inches Frequency of flooding: Occasional Frequency of ponding: None Available water storage in profile: High (about 12.0 inches) Interpretive groups Land capability classification(irrigated): None specified Land capability classification(nonirrigated): 3w Hydrologic Soil Group: B Other vegetative classification: Seasonally Wet Soils (G002XN202WA) Hydric soil rating: No Data Source Information Soil Survey Area: Mason County, Washington Survey Area Data: Version 13, Sep 7, 2017 USDA Natural Resources Web Soil Survey 12/17/2017 Conservation Service National Cooperative Soil Survey Page 1 of 1 Map Unit Description:Everett gravelly loamy sand,5 to 15 percent slopes—Mason County, Washington Mason County, Washington Ee—Everett gravelly loamy sand, 5 to 15 percent slopes Map Unit Setting National map unit symbol: 2hk7 Elevation: 50 to 500 feet Mean annual precipitation: 55 to 90 inches Mean annual air temperature: 48 to 50 degrees F Frost-free period: 160 to 180 days Farmland classification: Farmland of statewide importance Map Unit Composition Everett and similar soils: 100 percent Estimates are based on observations, descriptions, and transacts of the mapunit. Description of Everett Setting Landform: Terraces Parent material: Glacial outwash Typical profile H1 -0 to 7 inches: gravelly ashy loamy sand H2- 7 to 21 inches: extremely gravelly sand H3-21 to 60 inches: very gravelly sand Properties and qualities Slope: 5 to 15 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Somewhat excessively drained Capacity of the most limiting layer to transmit water(Ksat): High to very high (5.95 to 19.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Very low(about 2.5 inches) Interpretive groups Land capability classification(irrigated): None specified Land capability classification (nonirrigated): 4s Hydrologic Soil Group: A Other vegetative classification: Droughty Soils (G002XN402WA) Hydric soil rating. No Data Source Information Soil Survey Area: Mason County, Washington Survey Area Data: Version 13, Sep 7, 2017 uswn Natural Resources Web Soil Survey 12/17/2017 Conservation Service National Cooperative Soil Survey Page 1 of 1 L � Map Unit Description:Indianola loamy sand,5 to 15 percent slopes—Mason County, Washington Mason County, Washington lb—Indianola loamy sand, 5 to 15 percent slopes Map Unit Setting National map unit symbol: 2t635 Elevation: 0 to 980 feet Mean annual precipitation: 30 to 81 inches Mean annual air temperature: 48 to 50 degrees F Frost-free period: 170 to 210 days Farmland classification: Prime farmland if irrigated Map Unit Composition Indianola and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transacts of the mapunit. Description of Indianola Setting Landform: Eskers, kames, terraces Landform position (three-dimensional): Riser Down-slope shape: Linear Across-slope shape: Linear Parent material: Sandy glacial outwash Typical profile Oi- 0 to 1 inches: slightly decomposed plant material A - 1 to 6 inches: loamy sand Bw1 - 6 to 17 inches: loamy sand Bw2- 17 to 27 inches: sand BC-27 to 37 inches: sand C-37 to 60 inches: sand Properties and qualities Slope: 5 to 15 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Somewhat excessively drained Capacity of the most limiting layer to transmit water(Ksat): High to very high (5.95 to 99.90 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 3.9 inches) Interpretive groups Land capability classification(irrigated): 4e Land capability classification(nonirrigated): 4s Hydrologic Soil Group: A Other vegetative classification: Droughty Soils (G002XN402WA), Droughty Soils (G002XS401 WA) USDA Natural Resources Web Soil Survey 12/17/2017 Conservation Service National Cooperative Soil Survey Page 1 of 2 Map Unit Description:Indianola loamy sand,5 to 15 percent slopes—Mason County, Washington Hydric soil rating: No Minor Components Alderwood _ Percent of map unit: 8 percent Landform: Ridges, hills Landform position (two-dimensional): Shoulder Landform position (three-dimensional): Nose slope, talf Down-slope shape: Linear, convex Across-slope shape: Convex Hydric soil rating: No Everett Percent of map unit: 5 percent Landform: Kames, eskers, moraines Landform position (two-dimensional): Shoulder, footslope Landform position (three-dimensional): Crest, base slope Down-slope shape: Convex Across-slope shape: Convex Hydric soil rating: No 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 13, Sep 7, 2017 r;sDk Natural Resources Web Soil Survey 12/17/2017 Conservation Service National Cooperative Soil Survey Page 2 of 2 i Please print,sign and return to the Department of Ecology `'' Water Well Report Current nd 0 Origlnd-Ecology, 1 copy-oweeq 2 copy-ddaer Notice of Intent No. W 178538 C Co struction/Deeommission Unique Ecology Well ID Tag No. AKS 246 Construction Water Right Permit No. Decommission ORIGINAL INSTALLATION Notice Property Owner Name_Robext Wright of Intent Number Well Street Address 91 NE Timberland Dr, PROPOSED USE: $]Domestic ❑ Industrial B Municipal City Belfair County I�IaSon _y ❑DeWater ❑Irrigation ❑Test Well Other CI TYPE OF WORK: Owner's number of well(if more than one) Location S—W1/4-1/4 S 1/4 Sec�0Twn23 R�1 EwM circle C M New well❑Dee wwM 0" 0 Deepened ❑Reconditioned Mrthud:❑Dug ❑Bored ❑ Driven Lat/Lon /S t r Lat De Lat Min/See Pe ®cable Rotary ❑Jetted \ , , 8 r— DIMENSIONS: Diameterofwell 6 inches,dn I led aft. still REQUIRED ) Long Deg Min/Sec Depth of completed well �?(1 fl. to CONSTRUCTION DETAILS Tax Parcel No. 12320-43-90140 Cuing ($Welded 6 Diam.from +1—ft.to 115_ft. E Installed: B Liner installed Dram.from ft.to ft. CONSTRUCTION OR DECOMMISSION PROCEDUR19 Threaded Diann.from ft.to fl. Perforations: 0 Yes IM No Formation: Describe by rolor,character,size of material and structure,and the kind and Type of perforator used nature of the material in each stratum penetrated,with at least one entry for each change of information indicate all water encountered. USE ADDITIONAL SHEETS IF NECESSARY. SIZE of perfs in.by—in,and no.of perfs_from_fl.to_ft. ' MATERIAL FROM TO Screens: [2Yes []No [RK-Pac Location 113 Manufacturer's Name Mgadka Type Gta i 131ects Model No. Diem. Slot size from T2-L ft.to fl. L' Diam Slot size from ft.to ft. Gravel/Filter packed:❑Yes MNo [_-]Size of gmveUsand t� Materials placed from ft.to ft. iQ+ Surface Seel::$J Yes ❑No To what depth? 18 R Material used in seal BetnnitA' Fine qrav sand with 106 120 Did any strata contain unusable water? ❑Yes 13No i.+ Type of water'? Depth of strata Method of sealing strata off C PUMP: Manufacturer's Name L Type: sub H.P. 1 WATER LEVELS: Land-surface elevation above mean sea level ft. Static levels ft.below top of well Date Artesian pressure lbs,per square inch Date O Artesian water is controlled by (cap,valve etc. z WELL TESTS: Drawdown is amount water level is lowered below static level U) Was a pump test made'?El Yes 5a No If yes,by whom'? 4) Yield: Umin.with ft.drawdown after hrs. Yield: I./min.with ft.drawdown after hrs. Yield: ualJmin,with ft.drawdown after hrs. Recovery data(lime sedan as zero when putap turned ug)(water level mamured from well i vY' top to water level) OTime Water Level Time Water Level Time Water Level v washillutoll State w Date of test Department 0 k:C. 0t- ' �.a Bailer test_30 golJmtn.with 60 ft,drawdown after hrs. C Airiest gal./min.with stem set at 0.for hrs. Artesian flow a p.m. Date E Temperature of water Was a chemical analysts made'! ❑Yes ®No L. Start Dade 7 04 Completed Date 7/13/04 CL WELL CONSTRUCTION CERTIFICATION: 1 constructed and/or accept responsibility for construction of this well,and its compliance with all W Washington well construction standards. Materials used and the information reported above are true to my best knowledge and belief. 0 Driller/Engincer/rrainee Name(PrinQ — M-R�!F- 140rini nQSEM Drilling Company r)ayi R Dri 1 1 i tnoa .� Driller/Engineer/Trainee Signature Address 3Q Me Da IiB FaM RC3. Driller or trainee License No. 22 4 City,state.Zip Belfair,, WA 98528 If TRAINEE. Conaactor's Driller's Licensed No. Registration NoDAVISDI110taA Dote V oLK Driaw's Signature Ecology is an Equal Opportunity Employer. ECY 050-1-20(Rev 2/03) GE010 - OW 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 referthe case to the Planning Manager or Director. Applicant's Name: Permit#: CLIO Im-t " 110 1" Parcel#'s: 17 y_a'�`1 - 0 Date(s)of the Document(s) reviewed: �� 6 1. A discussion of geologic conditions in the general vicinity of the proposed development, with geologic unit designation based on referenced maps. OK?-X Comment: 2. (a) A discussion of the ground water conditions at the site, OK? Comment: (b) A discussion of the estimated depth to water, OK?�_Comment: (c) A discus of of the quantity of surface seepage, OK? / Comment: (d) A discussion of the upslope geomorphology, OK? Comment: (e) A discu sion of location of upland waterbodies and wetlands. OK? Y Comment: 3. The approximate depth to hard or dense competent soil, e.g. glacial till or outwash sand. OK?X Comment: 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 m�ovvement, etc.). OK? / Comment: 5. A discussion of the history of landslide activity in the vicinity, as available in the referenced maps and records. OK? X 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 proposed development. OK?X Comment: 7. A recommendation by the preparer whether a Geotechnical Report should be required to further evaluate site conditions apd.the proposed development of the subject property. OK? Comment: 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: Page 1 of 2 Form Effective June 2008 (a) the area of the proposed development, OK? Comment: (b) the boundaries of the landslide hazard area (top, both sides, and toe), OK? Comment: (c) the associated buffers (top, both sides, and toe) OK? Comment: (d) building or other setbacks (top, both sides, and toe). OK? Comment: 9. A site map drawn to scale showing the property boundaries, scale, north arrow, and the location and nature of existing and pr posed development on the site. OK?_7 Comment: Are the Documents signed and stamped? �� By whom? x c IS CM License#: ll License type: FIRST REVIEW Approved ❑ Need more info. If not approved, what is the next action/recommendation for further action? Reviewed by f - , on I q . Time spent in review: SECOND REVIEW/UPDATE ❑ Approved ❑ Need more info. If not approved, what is the next action/recommendation for further action? Reviewed by on . Time spent in second review: THIRD REVIEW/ UPDATE ❑ Approved ❑ Need more info. If not approved, what is the next action/recommendation for further action? 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 I �