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HomeMy WebLinkAboutGEO2011-00024 for BLD2011-00101 - GEO Geological Review - 3/10/2011 Mason Countv 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/OwnerLeVMdJ,✓ i;� 4AV 57 Parcel# 327-32 SS Jgo©/7 Site Address 3si E Acpea v�/ koaJ , L2L1--Q0 (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) (2) (a)A discussion of the ground water conditions at the site, Located on page(s) S (b) A discussion of the estimated depth to water Located on page(s) .S (c) A discussion of the quantit of surface seepage Located on page(s) (d) A discussion of the upsloQe geomorphology Located on page(s) L (e) A discussion of location of upland waterbodies and wetlands. Located on page(s) 2- (3) The approximate depth to Lard or dense competent soil, e.g. glacial till or outwash sand. Located on page(s) 4- (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) ,3 (5) A discussion of the history of landslide activity in the vicinity, as available in the referenced maps and records. Located on page(s) _ 7 (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) 1� (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) (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 d elopment, Located on Map(s) A/ (b) the boundaries of the landslide hazard area (top, both sides, and toe), Located on Map(s)_�IA (c) the associated buffers (to both sides, and toe) Located on Map(s) � (d) building or other setback (top, both sides, and toe). Located on Map(s) M (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) S.4c- Plan I, /"(i c�l�� �i1' - ►evt hereby certify under y S� penalty of perjury thaf I am a civil engineer licensed in the State of Washington 9 g n 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/ar J0. 20i( , and entitled 6e 5-,L S%n�/ryr1:�v /C�S,�ec��a �ro/ 6' meets all the requirements of the M sa on County Re ource Ordinance, Land lide 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) C1L � 3//0// s�QNAL Disclaimer: Mason County does not certify the quality of the work done in this Geological Assessment. Page 2 of 2 Form Effective June 2008 645o aoll 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: (71 ( Permit#: 60,2D 11-/el P rcel#'s: 3�31 J 5� OHO Date(s) of the Document(s) reviewed: �� 1 1. A discussion of geologic conditions in the general vicinity of the proposed development, with geologic unit designation based on referenced maps. OK? C" Comment: 2. (a) A discussion of the ground water conditions at the site, OK? 41"� Comment: (b) A discussion o the estimated depth to water OK? Comment: (c) A discussion of the quantity of surface seepage OK? y Comment: (d) A discussion of the upslope geomorphology OK?_ t-,� Comment: (e) A discussion f location of upland waterbodies and wetlands. OK? Comment: 3. The approximat epth to hard or dense competent soil, e.g. glacial till or outwash sand. OK? 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 movement, etc.). OK? Comment: 5. A discussion of the history of landslide activity in the vicinity, as available in the referenced maps and records. OK? ✓ 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? Comment: /?0 f "'t • t T 7. A recommendation by the preparer whether a Geotechnical Report should be required to further evaluate site conditions and the proposed development of t e s bject pro a OK? Comment: /eeo 5 ero Sl`w JW fiY,t L�.� o/ /a... Page 1 of 2 Form Effective June 2008 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: (b) the boundaries of the landslide hazard area (top, both sides, and toe), OK?4�A—Comment: (c) the associated buffers (top, both sides, and toe) OK?_Alb' 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 proposed development on the site. OK? `� Comment: Are the Documents signed and stamped? By whom? //df do-e/ J/..- License#: Y License type: _...._.._...._.........._...--....- ---—-- -- ._..................._....__.._.._....._._._..........-.................--...__..._... -----...._.._.._..._..._..----.... -- --..__._...._..-_........................--...... ----- FIRST REVIEW If not approved, what is he next action/recommendation for further action? Reviewed by on Time spent in review: Y _ �✓off v-s�.M f S� o/. �� � Ply^ ��. 3-!l- << ......_.._...-.................---.............--............._..__._....._ --- ......_..............— ----- —_ ---- ----- -- SECOND REVIEW/ UPDATE Reviewed by on . Time spent in second review: —.__...-........_.._.... _- -...--- .._.__....-- -- --._.---..................-.....................................................................................................-- THIRD REVIEW/UPDATE Reviewed,py 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 Geological Assessment for Geist Single Family Residential Property 351 E McReavy Road Parcel No. 32232 55 00017 Mason County, Washington March 10, 2011 Project#1128 Prepared For: Leander and Kathy Geist PO Box 604 Ly CLYIDF sT Union, Washington 98592 �G ��o WASHI'1'G,9)� Prepared By: //0/// Envirotech Engineering P. 43045 w4 a� '�F- PO Box 984 lis Belfair, Washington 98528 SSI�NAL��G Phone: 360-275-9374 Fax: 360-275-4789 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..............................................................................................................2 2.1 GENERAL OBSERVATIONS............................................................................................................2 2.2 TOPOGRAPHY............................................................................................................................... 2 2.Z1 Upslope Geomorphology and Upland Water Bodies.............................................................. 2 2.3 SURFACE DRAINAGE.....................................................................................................................2 2.4 SLOPE AND EROSION OBSERVATIONS........................................................................................... 3 3.0 SUBSURFACE INVESTIGATION.................................................................................................4 3.1 FIELD METHODS,SAMPLING AND FIELD TESTING........................................................................4 3.2 GEOLOGIC CONDITIONS...............................................................................................................4 3.3 SPECIFIC SUBSURFACE CONDITIONS.............................................................................................4 3.3.1 Groundwater......................................................................................................................... 5 3.4 SOILS TESTING............................................................................................................................. 5 3.4.1 Visual Classification............................................................................................................. S 4.0 ENGINEERING CONCLUSIONS.................................................................................................6 4.1 LANDSLIDE HAZARDS...................................................................................................................6 4.1.1 Landslides and Slope Stability Analysis................................................................................ 8 4.1.2 Surface and Subsurface Drainage........................................................................................ 8 4.2 EROSION HAZARDS.......................................................................................................................8 4.3 SEISMIC HAZARDS........................................................................................................................8 4.4 OTHER CONSIDERATIONS.............................................................................................................9 5.0 CLOSURE..................................................................................................................................... 10 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 351 E. McReavy Road, identified as parcel number 32232 55 00017 in Union, 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 without the property owner, Leander and Kathy Geist on March 9, 2011. 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 property is accessed from both McReavy Road and Warren Drive. The property consists of an existing home, gravel driveway, and on-site septic features. The proposed development is expected to consist of a new single family residence replacing the existing mobile on nearly the same foo tint and an attached 24ft x 24ft gMge. Approximate site deve opment 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; • Complete an engineering assessment supported by planned site alterations and the surface and subsurface conditions that were identified by the field investigation, and applicable Project research; and, • Establish engineering conclusions based on findings and anticipated Project. Envirotech Engineering Geist Geological Assessment Ph. 360-275-9374 page 1 Parcel 32232 55 00017 Fax: 360-275-4789 Mason County, Washington March 10,2011 2.0 SURFACE CONDITIONS Information pertaining to the existing surface conditions for the Project was gathered on March 9, 2011 by Michael Staten,geotechnical engineer 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 developed land as previously mentioned, and surrounded by rural residential development. The existing home to be replaced is approximately 50ft x 16ft in size. McReavy Road extends along the south side of the property,and Warren Drive extends along the north. Vegetation on and near the property consists primarily of 2"d growth 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 Project is situated within and near moderate terrain. 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 the property. This slope is approximately 18% with a vertical relief of approximately 37 feet before descending to an average slope of 33%. 2.2.1 Upslope Geomorphology and Upland Water Bodies Ascending grades are generally located to the south of the planned development. This sloe is relatively minor within 300 feet of the Project. Except for the roadway P Y J eP Y embankment, there are no apparent slope grades of at least 15%. The upland area of the property is situated on a gentle hillside near the crest. Additional geomorphology that is pertinent to both upslope and downslope areas are provided in the Subsurface Investigation Section of this report. There are no apparent water bodies or wetlands located upslope from the planned development that would significantly influence the Project. 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 Project. Runoff is intercepted on the south side of Mcreavy Road, and transported beyond the property.The south side of Warren Drive transports water from site runoff to a mitigated drainage conveyance. Currently, roof drainage exits downspouts around the existing home. Curtain drains were reported, and one was apparently observed on-site. Envirotech Engineering Geist Geological Assessment Ph. 360-275-9374 page 2 Parcel 32232 55 00017 Fax: 360-275-4789 Mason County, Washington March 10,2011 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. as i I • Mason "1 ,s+ } 32 r22N R3W WA% : s Aerial Photo from USDA SCS Website Envirotech Engineering Geist Geological Assessment Ph. 360-275-9374 page 3 Parcel 32232 55 00017 Fax: 360-2754789 Mason County,Washington March 10,2011 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 9, 2011 by Michael Staten, geotechnical engineer 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 observing soils within test pit excavations of up to approximately 2.5 feet below the existing ground surface. 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. Field testing results generally indicated medium dense soils in the upper 18 inches, and dense soils from 18 inches below the ground surface to the depth of terminous. 3.2 Geologic Conditions In general, soils at the project are composed of materials from glacial advances. The geologic conditions as presented in the "Geologic Map of Washington," compiled by J. Eric Schuster, 2002 indicates Quaternary sediments, Qg. Quaternary sediments are generally unconsolidated deposits,and dominantly deposited from glacial drift,including alluvium deposits. This project is located within the Puget Lowland. Typically, "lower tertiary sedimentary rocks unconformably overlie the Crescent Formation."as revealed in the Geologic Map. Initial sedimentary rocks were formed from shales, sandstones and coal deposits from rivers. During the Quaternary period, the Puget Lowland was covered by numerous ice sheets,with the most recent being the Fraser glacier with a peak of approximately 14,000 years ago. Upon the glacial retreat, the landscape was formed by glacial erosion glacial drift deposits. According to the "Geologic Map of the Shelton 1:100,000 Quadrangle, Washington," by Robert L. Logan, 2003, the site soils are subgrouped as Alpine Glacial Deposits. Specific units for this Project include alpine outwash, pre-late Wisconsinan(Pleistocene), %po. From this geologic map, Q8po is "stratified sand, gravel and cobbles; in the Quinault basin, clasts consist of sandstone and less-abundant basalt from the Olympic Mountains core and peripheral rocks; in streams draining the southern and southeastern Olympics, clasts consist primarily of Crescent Formation basalt with less-abundant Olympic-core sandstone; may include peat, silt, and clay, and may be capped by weathered loess; clasts are generally more rounded than those in till and lack facets and striations; poorly to moderately sorted;gray to subtle yellow with wispy orange weathering." 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 Envirotech Engineering Geist Geological Assessment Ph. 360-275-9374 page 4 Parcel 32232 55 00017 Fax: 360-275-4789 Mason County,Washington March 10,2011 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 composed of native soils and minor fill areas. Competent bearing soils were encountered at 18 inches below the native, non-fill, ground surface. For engineering purposes, these native soils consist of distinguishable layers, as presented below. Soils within the upper 2.5 feet of natural ground were observed to be moist,brown silty sand with gravel (SM). Soils below the upper 2.5 feet layer are believed to be silty sand (SM) and gravelly (GM, GP) soils with hardpan. This is based on nearby well reports, site geology, and/or knowledge of the general area. The relative densities of the soil are provided above in Section 3.1. 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 upland site soils are described as Alderwpod gravelly sandy loam, k,with 15%- 30%slopes. See the SCS soil profiles in Appendix B of this report. 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. Seepage or perched groundwater at shallow depths was not observed on-site, nor indicated on the well reports. 3.4 Soils Testing Laboratory testing of soil samples were not performed for this Project. Visual classification of soils was performed in the field. The following soil tests were performed in accordance with the American Standards for Testing and Materials (ASTM): 2 Visual Classifications(ASTM D2488) 3.4.1 Visual Classification The general results from the visual classification are presented above in the Subsurface Conditions Section. Specifically, soils within the upper 4 feet in the testing location consisted of approximately 35%coarse gravel,45%sand-sized soils,and 20%low plastic silt. 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. Envirotech Engineering Geist Geological Assessment Ph. 360-275-9374 page 5 Parcel 32232 55 00017 Fax:360-275-4789 Mason County,Washington March 10,2011 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, surface and subsurface conditions as presented in 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. Landslides are natural geologic processes, and structures near slopes possess an inherent risk of adverse settlement, sliding or structural damage due to these processes. Geotechnical engineering cannot eliminate these risks for any site with sloping grades because gravity is constantly inducing strain on the sloping soil mass. Excessive wet weather and/ or earthquakes will exacerbate these strains. Geotechnical engineering considers excessive wet weather and `design' earthquakes in order to provide an acceptable factor of safety for developing on or near sloping terrain. These factors of safeties are based on engineering standards such as defining engineering properties of the soil,topography,water conditions, seismic acceleration and surcharges. Surface sloughing or other types of surficial slope movements usually do not affect the deep- seated structural capability of the slope. However, excessive and/or repeated surficial slope movements, if not repaired, may represent a threat to the structural integrity of the slope. Maintenance of the slope should be completed if the situation does arise in order to prevent the possibility of further surficial or deep seated slope movements that may be damaging to life or property. According to the Coastal Zone Atlas of Mason County, Washington, the Project is within and near terrain labeled `Stable' and `Intermediate' regarding potential landslide activity. Stable slopes are generally not prone to landslides due to small grades and accommodating geology. Historically, intermediate terrains have no known landslides. A site specific analyses and conclusions concerning the slopes are presented herein. A Stability Map from the Coastal Zone Atlas for the general area of this Project may be found below. Envirotech Engineering Geist Geological Assessment Ph. 360-275-9374 page 6 Parcel 32232 55 00017 Fax: 360-275-4789 Mason County, Washington March 10,2011 ` s a) Project Map from Washington State Department of Ecology Website According to the Resource Map from the Washington State Department of Natural Resources (DNR), the Project is not within terrain labeled `highly unstable' or `highly erodible' relating to soils. In addition, DNR did not indicated previous landslide activity near the Project. DNR labeled portions of this project as medium 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: t79dB06 /9biI18 tIT0.5000 8 Pu9aT sarra i PHI foe W 7g�9g 01080 ai � V a Project ` c l r � F r� /r a t ..�_ .. Teaasa *Toswo Map from Washington State Department of Natural Resources Website Envirotech Engineering Geist Geological Assessment Ph. 360-275-9374 page 7 Parcel 32232 55 00017 Fax: 360-275-4789 Mason County,Washington March 10,2011 4.1.1 Landslides and Slope Stability Analysis Past landslide activity 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 Conditions Section of this report. Therefore, a slope stability analysis was not deemed necessary for this Project. Considering the planned construction as summarized in the Introduction Section of this report; surface and subsurface conditions for the Project; and, the slope stability assessment provided herein, it is our opinion that the proposed site alterations will not encourage a landslide hazard. 4.1.2 Surface and Subsurface Drainage Although runoff is moderate to high within the vicinity of the project, 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 moderatelv erodible. According to the Resource Map from the Washington State DNR, as provided above, e Project is not within terrain labeled `highly erodible.' However, this Project is 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 (CS), 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). -- A temporary and permanent erosion control plan is required for this project. Currently, the owner has exercised prudent erosion control practices thus far. The existing ballast driveway and straw matting within denuded areas are working effectively. The owner forethought concerning erosion control is expected to continue until final site stabilization is complete. 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 Hood Canal Fault Zone. This fault is a Class `B,` and is located approximately 4 miles to Envirotech Engineering Geist Geological Assessment Ph. 360-275-9374 page 8 Parcel 32232 55 00017 Fax: 360-275-4789 Mason County, Washington March 10,2011 the northwest of the Project. This information is supported by the USGS Quaternary Fault and Fold Database for the United States. The potential for liquefaction and other earthquake induced hazards are believed to be low for this Project. This is based on subsurface conditions such as soil characteristics and the lack of a permanent and substantial shallow water table. Subgrade characteristics that particularly contribute to problems caused by seismic events include submerged and confined, poorly-graded granular soils. Although gravel- and silt-sized soil particles could be problematic, fine and medium grained sands are typically subjected to these types of seismic hazards. 4.4 Other Considerations It is expected that existing on-site drainage practices will continue for the proposed development. Conclusions in this report are based on the type and location of the anticipated development, and existing surface and subsurface conditions. Site development that significantly deviates from the anticipated improvements presented in this report may require geotechnical design recommendations. Envirotech Engineering Geist Geological Assessment Ph. 360-275-9374 page 9 Parcel 32232 55 00017 Fax: 360-2754789 Mason County, Washington March 10,2011 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 a qualified engineer observes and documents the construction, or 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 Geist Geological Assessment Ph. 360-275-9374 page 10 Parcel 32232 55 00017 Fax: 360-275-4789 Mason County,Washington March 10,2011 APPENDIX A SITE MAP SCALE- I INCH = 40 FEET +1 0 5 10 20 40 m WARREN DRIVE SEPTIC41 EXISTING F- +I DRAINFIELD AREA Cp PROPERTY LINE o � to TP11 APPRX, LOCATION OF EXISTING HOME TO BE REPLACED WITHIN NEARLY SAME BUILDING F❑OTPRINT EXISTING GRAVEL PROPOSED GARAGE DRIVEWAY (APPRX) (APPRX) 100FT + E MCREA VY ROAD PROJECT/ OWNER/ LOCATIOIb SINGLE FAMILY PROPERTY GE❑LOGICAL ASSESSMENT GEIST 351 E McREAVY ROAD PARCEL 32232 55 00017 MASON COUNTY WASHINGTON LEGEND ENGINEER- ENVIROTECH ENGINEERING SLOPE INDICATOR 74 NE HURD ROAD BELFAIR, WASHINGTON 99528 360-275-9374 TPIj@ TEST PIT SITE PLAN APPENDIX B SOIL INFORMATION F - TEST PIT LOG TEST PIT NUMBER TP-1 PROJECT: SFR Geological Assessment DATE OF LOG: 03/09/2009 PROJECT NO: 1128 LOGGED BY: MCS CLIENT: Geist EXCAVATOR: N/A LOCATION: Parcel 32232 55 00017 DRILL RIG: None Mason County, Washington ELEVATION: N/A INITIAL DEPTH OF WATER: NIA FINAL DEPTH OF WATER: N/A STANDARD PENETRATION TEST SOIL STRATA, ' DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE AND TEST DATA DEPTH N 10 30 50 0 ......... ................ . . . SM Light brown, moist, medium dense SILTY SAND with GRAVEL. Gravel is coarse and subrounded. Sand is primarily 1 medium and coarse. Low plasticity. Dense. Some cobbles, increasing gravel. 2 - Excavation terminated at approximately 3 2.5 feet 4 5 6 7 8 9 10 No Groundwater Encountered ENVIROTECH ENGINEERING This information pertains only to this boring and should not be Geotechnical Engineering interpreted as being indicitrw 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 Elevation: 50 to 800 feet Mean annual precipitation: 25 to 60 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 180 to 220 days Map Unit Composition Alderwood and similar soils: 100 percent Description of Alderwood Setting Landform: Drainageways Parent material: Basal till with a component of volcanic ash Properties and qualities Slope: 15 to 30 percent Depth to restrictive feature:24 to 32 inches to dense material 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 36 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Very low(about 2.5 inches) Interpretive groups Land capability(nonirrigated): 4e Typical profile 0 to 10 inches: Gravelly sandy loam 10 to 28 inches: Very gravelly sandy loam 28 to 60 inches: Gravelly sandy loam Data Source Information Soil Survey Area: Mason County, Washington Survey Area Data: Version 6, Sep 22, 2009 l Natural Resources Web Soil Survey 3/9l2011 Conservation Service National Cooperative Soil Survey Page 1 of 1 Ftle Original and First Cop?with Asiplmcation No. •i Department.4 EcoloKy WATER WELL REPORT --- a Thud nd Q,pyY Dr=errs COpjCopy STATE OF WASMNGTON Perwlt NqZ 1_;_ (� (1) 6vt71VE - Name.--- 'f'1 Address----------- ---------- - _. . ...... _ . .. ................... .._..... ... (t) LOCATION OF WELL: cottnsr-.. .. _.... _ ._.. . ........... - ....... �; -54 ,:Ser....30 T : N. R, (sf w.M. Ileariag and distance from section or subdivision corner �[>' NO N (3) PROPOSED USE: Domestte Q Ind..., ❑ M.M.lpal Q (10) WELL LOG: trrigation ❑ Test well ❑ Other ❑ Formation:Describe bit color,character,size of matertat and structure,and traattum Penetratss teed,aquifers l h at least ore entand the kind ry fort erachr the changeaofrf 1 in each formation. 0 (4) TYPE OF WORK: ')"s number of well sit I ut more than one).... .........................._.._.._. __ MATERIAL rftOa[ TO New well Q Meti �il lod:. ug • Q Bored-O 0 -'Cable - - t 0 Deepened [7 . _.cable ❑ -Drtvrn_D Recommdltlizned ❑ =Retat7A Jetted ❑ G (S) DIMENSIONS: Diameter of well`,.....: - -- — �, Drtiled._._...._......_.._......ft. Depth of cotnplotid_weA....f!.2 ..:...._._ (6) CONSTRUCTION DETAUS: ,_ — 3i y,•-' Casinginstalled: '• - ^ Dlam- trM_.- ltr b .:.__:_:n. / L Threaded 0 _.._........... Diam.boas•_.^:1._.ff." y t �s 0 Welded " Dlam teyo..�.--T•.- .tn_.�..�1t. -- Perforations: Yes_M:.._...No❑ _-- e G t. Type of perforator used......-._..__ SIZE of perforation 'ta bl'-_._ Q .........._..._...perforations from __iN..___ ft-to.,aTv:_._..'fi. ^ pertoretfons from_1Q.�-.. ft.to -... ii. ,� ft. d --- perforations from ___....:__.._.. !C.to_:......._..._.._ it. 1jis J&JAYE' — e�+ Streeos: Yes A No Q S�',D _— Manulacturee'a Name ..._a __S `�-- s`• e� -.-...... b- Dlama--_.......... Slot size ........._..... to fiQ Diam. ._.......... Slot size ..._..........frotrt-- ft Gravel pack": Yes p No Q Size al.Nz+vN-��.._.._.:..:. .... O Gravel placed from.................I....._....... Surface seal: Yes❑ No Q To what depth? ......_:... ft. 0 Material used in seal.._....................... ..40 s _ 0 Did any strata contain unusable waiter? 4rerLt— No❑_ VType of water?....._.......... ...........--- Depth af,ate-------T Method of sealing strata off......................_..............:...__....._................ i 0 (7) PUMP: SP0 Type. ....- ... . - --- ..__ ._....---. -..,�......---._.. — W (S) WATER LEVELS: Lan'-surf"n Ai'rt e- 0 static level _......___.... .ft. below top otwetl 4.0 Artestan prewuR ..._- .-.... _lba. per square inch Arbestan water is eontrolled by.............. . .f..........._.... _._. _.._... QI Cap�Y�i�eto.) 11- (9 WELL TESTS: Drawdown u amrw+iat datrr level b_ — -_ — -- ) lowered beklvr static level Qwas a pump test made? Yes❑ No Q If yes.by whom? .::_......— _._._._.. workstart4d......__..------_..____.if_......... Completed....... ...--........__......... lf........_ a Yield: gal./min.with ft.drawdown'Wer hrs. WELL DRILLERS.STATEMENT' This well was drilled under my jurisdiction and this report is 41 - __ .• true to the best of my'knowledge and belief. necovcry data (tame taken as zero when pump:tue ul ned WT foer leveT measured from wren top to water leveil (�— iQ Time Water Level I Time Water Leset Ti Water Level NAME.-.---------- ..... ......... _.. 41 ........ ........... -........_................................... a _........... ------------- ............_... •......._-..........__ .c ------------------ -----._.-•---------------------------------------.- _.._._........__. Dateof fed ...------.......................................... [Signed]........................................ ..................__....._.........---....................... Bailer test-----.-•.salJmin. with_.._._.._.....ft.drawdown after..................bra. (Well Drillerl Artesian flow-------_--------_. .....................S.pm. Date.._.._.........._..................--.-. Temperature of water-------------.Was a chemical analysis made?Yes(] We Q L lee No............................................. Date.... ...-/.........__.,nZJ& �MSE ADDITIONAL SHIMM IF NECESSARY) X.F.No.7iii-•OS—lttev.4.71). _J'� 4W s I'