The URL can be used to link to this page

Home My WebLink AboutGEO2021-00089 for GRD2021-00010 - GEO Geological Review - 6/16/2018 qED � 6r-,J 202.1 -- D0d10 6Eo 2W-l - DUobl RECEIVED PLANNING AUG 0 5 2021 615 W. Alder Street Geotechnical/ Soils Report For Midwest Solutions Commercial Property 290 NE State Route 300 Parcel 12329-42-00020 Belfair, Mason County, Washington June 16, 2018 Project#18116 Prepared For: Midwest Solutions, LLC PO Box 3240 �� Belfair, Washington 98528 , Prepared By Envirotech Engineering 43043 PO Box 984 Belfair, Washington 98528 6, 16!18 Phone: 360-275-9374 TABLE OF CONTENTS 1.0 Introduction............................................................................................................................................2 2.0 Project Information...............................................................................................................................2 3.0 Surface Conditions.................................................................................................................................2 4.0 Subsurface Investigation.......................................................................................................................3 4.1 Infiltration Rates................................................................................................................................4 4.2 GroundAater......................................................................................................................................5 5.0 Engineering Conclusions and Recommendations...............................................................................5 5.1 Foundation Recommendations.........................................................................................................6 5.2 Seismic Considerations......................................................................................................................6 5.3 Earthwork Recommendations..........................................................................................................7 5.4 Soil Cation Exchange.........................................................................................................................8 5.5 Porous Parking Surface.....................................................................................................................8 6.0 Limitations and Closure........................................................................................................................9 Appendix A—Test Pit Location Plan Appendix B—Soil Information 1.0 Introduction Envirotech Engineering (Envirotech) has completed this geotechnical/ soils report for the Midwest Solutions Commercial property. The proposed development is located at 290 NE State Route 300 (Parcel 12329-42-00020) in Belfair, Mason County, Washington. See the Vicinity Map below for a general indication of the project location. I � U I F I Project I' , Vicinity Map from Mason County Website 2.0 Project Information Information pertaining to the Project Aas provided by the property owner and owner's representatives. The proposed development includes constructing a commercial building to be used for 3 separate businesses. and a potential 2"d building as a second phase. The primary building use is anticipated to include a restaurant and brewery. Additional development will include paved parking, ingress/ egress, and other ancillary features typical of this type of development. 3.0 Surface Conditions Information pertaining to the existing surface conditions for the project was gathered on June 4. 2018 by Michael Staten with Envirotech. During the site visit, site features were documented that may influence the project. The property is cleared of native vegetation and currently developed with a single family Envirotech Engineering Midwest Solutions Geotechnical Report Ph. 360-275-9374 Page 2 of 9 290 NE State Route 300 Fax: 360-275-4789 Belfair, Washington June 16.2018 residence. Vegetation is mostly a grass lawn. Beyond the relative slightly sloping terrain of the property, the ground gently slopes down at a grades less than 10% towards the northwest. Indications of long-term surface water were not observed on site. Excessive scour, erosion or other indications of past drainage problems were not observed within the immediate vicinity of the planned development. However. it is reported that surface water from the State highway funnels to the southeast corner of the property during larger storm events. 4.0 Subsurface Investigation Information on subsurface conditions pertaining to the project was gathered on June 4, 2018 by Michael Staten with Ern irotech. Information on subsurface conditions for the project was accomplished by observing one test pit excavation to a depth of 6 feet below the existing ground surface. Additional information on subsurface conditions was collected by reviewing published ►naps and other nearby subsurface data within the vicinity- of the project. Appendix A has test pit locations, and Appendix B has pertinent information on subsurface conditions for the project, including three test pit logs. Specifically, soils for this project were described utilizing the Unified Soil Classification System (USCS). Soil Conservation Service (SCS), and the U.S. Department of Agriculture (USDA) Textural Classification System. Soils within the upper 12 to 18 inches of natural ground were observed to be moist, dark brown, loose to medium dense silty sand (SM) with organics. Soils from 12 to 18 inches below the existing ground surface to the observed depth of tenninous were mostly reddish brown and light brown medium dense to dense silty sand and poorly-graded sand and silt (SM, SP-SM) with gravel. According to the USDA Textural Classification System, the upper 2 to 3 feet of soil were classified as sandy loam. The native soils below the upper sandy loam layer to the depth of terminous were classified as loamy sand. According to the "Soil Survey of Mason County," by the United States Department of Agriculture, Soil Conservation Service, the site soils are described as Saxon silt loam, S,, with 5% to 15% slopes. The soil designations are depicted in the aerial photograph below, and complete descriptions are provided in Appendix B of this report. Envirotech Engineering Midwest Solutions Geotechnical Report Ph. 360-275-9374 Page 3 of 9 290 NE State Route 300 Fax: 360-275-4789 Belfair, Washington June 16, 2018 •r„t. r� 1 IA r— y s , rs mnll lop m r A jo fit , Soil Survey From USDA Natural Resources Conservation Service Based on the fines content, erodibility of the site soils is considered to be low to moderate. Based on the fines content and fraction of clay within the fines content, settleability of the site soils is expected to be moderate, Permeability is expected to be high for this site due significance of moderate density, poorly graded granular soils. Expanded and specific subsurface descriptions, other than what is provided in this section, are presented in the soil logs located in Appendix B of this report. 4.1 Infiltration Rates Two sieve analysis tests on materials were completed in order to determine infiltration capacity for proposed stormwater management facilities. Specifically, we are providing infiltration rates base on the Soil Grain Si ze ze Analysis Method as outlined in the 2012 Stormwater Management Manual for Western Washington. Based on our laboratory results and the aforesaid drainage manual, infiltration was determined to be the following: Logio(K.t)_-1.57+1.90D,o+0.015D60—0.0131390—2.08ffj„'., where, Kam,=saturated hydraulic conductivity, cm/sec Envirotech Engineering Midwest Solutions Geotechnical Report Ph. 360-275-9374 Page 4 of 9 290 NE State Route 300 Fax: 360-275-4789 Belfair, Washington June 16,2018 No = soil sample 10% finer by weight, mm D60= soil sample 60% finer by weight, mm Duo= soil sample 90% finer by weight, mm fenes= soil fraction passing#200 seive, by weight, mm Loglo(K.,)_-1.57+1.90(0.09)+0.015(.19)—0.013(0.26)—2.08(0.04) _ -1.48273 • Ksat= 10-1.48273=0.03290561408 cm/sec=46.64 in/hr Ksat design= Ksat x CFT CFT=CFv+ CF,+ CF,,, Ksa,=46.64 in/hr CFv = 1.0 (0.33 to 1.0) site variability and number of test locations CF, = 0.4 (0.4) grain size test method CF,,,= 0.9 (0.9)degree of influent control Ksatdesip= 16.8 in/hr 4.2 Groundwater According to water well reports and knowledge of the area, permanent groundwater is expected to be within a range of 20 to 30 feet below the around surface for this project. However, a thin layer of groundwater flow has been found throughout the year within the vicinity of the project at depths as shallow as 4 feet. Mottling was observed in test pit 1 at a depth of 5 feet which may indicate seasonal groundwater. 5.0 Engineering Conclusions and Recommendations The following sections present engineering assessments and conclusions concerning the proposed development of the project. These conclusions have been made available based on the planned improvements 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. It is apparent that the proposed development is not within 300 feet of a landslide hazard area or its associated buffer or setback as defined in the Mason County Resource Ordinance. Project development that includes buildings, traffic areas, and stormwater facilities on relatively flat ground are not of concern with respect to landslides. Based on the soil classification of the project soils, the upper 4 feet of soils have a moderate erodibility factor. Temporary erosion control measures may be minimal for this Project. This is due to the small nature of this project, relatively flat grades, and observed soil characteristics. Envirotech Engineering Midwest Solutions Geotechnical Report Ph. 360-275-9374 Page 5 of 9 290 NE State Route 300 Fax: 360-275-4789 Belfair, Washington June 16,2018 Temporary erosion should include standard controls such as a stabilized construction entrance and temporary sedimentation ponds or silt fencing. Permanent erosion control should be employed for all applicable site features such as culvert inlets and outlets, surface areas for traffic, and denuded areas. Additional erosion control measures may need to be employed during and/ or after construction if selected erosion control measures are not perfor ming mmg as expected, or required by the project engineer, County or other prevailing agency. 5.1 Foundation Recommendations It is anticipated that a monolithic slab with downturn foundations will be used. Stepped foundations are acceptable, if warranted for this project. Continuous, isolated, or stepped foundations shall be horizontally level between the bottom of the foundation and the top of the bearing strata. The frost penetration depth is not expected to extend beyond 12 inches below the ground surface, and final cover for foundations should be at least 12 inches. A modulus of subgrade reaction of no more than 140 pci should be used for the foundation system. Friction between the bottom of the foundation and soil may be utilized to resist lateral loads. A coefficient of friction of 0A may be used for this application, and should account for the vertical dead loads only. Foundations shall be established on relatively undisturbed native soil. Alternatively. foundations may be constructed on compacted engineered fill. For a bearing capacity requirement of no more than 1500 psf, footing widths for continuous foundations should be 15 inches. Foundations should be placed below the upper loose organic laden soils a minimum of 18 inches below the existing ground surface. For a columnar load of no more than 3 tons, a circular or square isolated foundation diameter or width shall be at least 30 inches. Based on the expected native soil conditions, anticipated development, and construction abides by the recommendations in this report, the assumed foundation system may undergo a maximum of 1.0 inch total settlement, and a maximum differential settlement of 0.5 inch. Interior slabs should be supported on a minimum of 6 inches of compacted coarse, clean, granular material (Retained U.S. Sieve #8 or greater) with less than 10% fines (passing U.S. Sieve #200) that is placed over undisturbed, competent, prepared native subgrade or engineered fill. Loading on slabs should be not more than 250 psf. Vapor barriers should be placed beneath the slab per applicable codes for mitigating excessive moisture in the building. 5.2 Seismic Considerations The following seismic parameters should be used for this project: Envirotech Engineering Midwest Solutions Geotechnical Report Ph. 360-275-9374 Page 6 of 9 290 NE State Route 300 Fax: 360-275-4789 Belfair. Washington June 16.2018 Seismic Site Class: Site class C to D Seismic Site Class Description: Average shear wave velocity in the upper 100 feet (30 meters)corresponds to a C site class and the mean shear wave velocity minus one standard deviation within the upper 100 feet(30 meters) corresponds to a D site class. Seismic Design Category Code: D2 Seismic Design Category (SDC): Seismic design category D2 SDC Description: 0.83 < S(DS) <= 1.17. where S(DS) is the 5 percent damped design spectral response acceleration at short periods Based on soil conditions and mapped geology,the potential for liquefaction is believed to be low for this project. According to the Interactive Geological Map of Washington, liquefaction hazards are very low to low within the vicinity of the property. 5.3 Earthwork Recommendations Founding material for building foundations shall consist of undisturbed native soils to the specified foundation depths. Compacted engineered fill, or selective re-compacted native soils may be used to the extents provided in this Earthwork Recommendations Section. The following recommendations include excavations, subgrade preparation, type of fill, and placement of fill for building foundations. Excavation is recommended to remove fill. any excessive organic content or other deleterious material, if present, beneath foundations and to achieve appropriate foundation depth. Additional sub-excavation will be required for this Project if the soils below the required foundation depth are loose, saturated, not as described in this report, or otherwise incompetent due to inappropriate land disturbing, or excessive water trapped within foundation excavations prior to foundation construction. All soils below the bottom of the excavation shall be competent, and relatively undisturbed or properly compacted fill. If these soils are disturbed or deemed incompetent, re-compaction of these soils below the anticipated footing depth is necessary. Excavations shall be completely dewatered, compacted, and suitable before placement of additional native soil, engineered fill or structural concrete. For engineered fill or disturbed native soils that will be utilized as fill material directly beneath foundations, observation and/ or geotechnicai testing is required prior to foundation construction. The following placement and compaction requirements are necessary. For disturbed native soils or engineered fill beneath foundations, limits of compacted or re-compacted fill shall extend laterally from the bottom edge of the foundation at a rate of one horizontal foot for each foot of compacted or re-compacted fill depth beneath the foundation. See the illustration below-. Envirotech Engineering Midwest Solutions Geotechnical Report Ph. 360-275-9374 Pase 7 of 9 290 NE State Route 300 Fax: 360-275-4789 Belfair, Washington June 16.2018 FOOTING COMPACTED NATIVE SOILS OR ENGINEERED I FILL 1 UNDISTURBED SUBGRADE Both engineered fill and native soils used as compacted fill should be free of roots and other organics, rocks over 6 inches in size.. or any other deleterious matter. Because of moisture sensitivity, importing and compacting engineered fill may be more economical than compacting disturbed native soils. Import material or native soils free of organics may be used as engineered fill. If import material is utilized as structural fill material for placement in building pad areas, we recommend that it meets the current Washington State Department of Transportation Standard Specification for Road. Bridge and Municipal Construction (WSDOT), Section 9-03(14), for Gravel Borrow. The material should be placed per the recommendation in section 2-06 of WSDOT for sub-grade. Material should be placed in 12" vertical lifts and compacted with a vibratory smooth drum roller to achieve 95% of the (ASTM D1557) modified proctor. Each lift surface should be adequately maintained during construction in order to achieve acceptable compaction and inter-lift bonding. Alternative materials may be imported for this project, and used for foundation support per the geotechnical engineer. Temporary earth cuts and temporary fill slopes exceeding 4 feet in height should be limited to a slope of 2:1 (horizontal:vertical). Utility trenches or other confined excavations exceeding 4 feet should conform to OSHA safety regulations. Permanent cut and fill slopes shall be limited to a slope of 2:1, unless otherwise approved by an engineer. 5.4 Soil Cation Exchange On-site loamy sand soils observed to a depth of 6 feet will serve as the required 18 inches of water quality treatment layer. The in-situ soils exhibits a cation exchange capacity in the range of 8 to 12 meq/100 grams of dry soil. 5.5 Porous Parking Surface The porous driveway/ parking section should consist of a layer of pervious pavers or permeable asphalt over a 2-inch choker course, over a 12-inch minimum stone storage gallery over a non-woven geotextile fabric over undisturbed, prepared subgrade. The layer of permeable asphalt shall be 2 inches minimum for light duty traffic, and 4 inches for heavy duty traffic. The use of pavers should have similar strength and durability characteristics. The 2-inch choker course shall consist of !!" crushed rock that is clean and uniformly Envirotech Engineering Midwest Solutions Geotechnical Report Ph. 360-275-9374 Page 8 of 9 290 NE State Route 300 Fax: 360-275-4789 Belfair, Washington June 16. 2018 graded. Alternately, the chocker course may consist of AASHTO grade No. 57 with a maximum stone size of 1 '/z". The stone gallery shall be a minimum of 12 inches deep, but the depth shall be sufficient for water storage per the civil engineer. AASHTO grade No. 3 stone, or other approved aggregate shall be used. In addition, the stone gallery shall have a minimum void space of 20%. The stone gallery shall be placed in loose lifts not to exceed 12 inches, and compacted by three passes with a «alk-behind lightweight vibratory roller or a vibratory tamping ing rammer The non-woven Qeotextile fabric shall be Marafi 160N or better. The geotextile shall be handled and placed per manufacturer's requirements. 6.0 Limitations and Closure Due to the inherent natural variations of the soil stratification and the nature of geotechnical subsurface explorations, 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 was prepared for the exclusive use for the development of the referenced project. Our report, conclusions and interpretations should not be construed as a warranty of the pervious parking. Pervious parking is a relatively new concept in order to meet stormwater management requirements. Pervious parking requires skilled, experienced labor for constructing this type of system. Performance has proved to var\ greatly, and overall long-term performance cannot be ascertained. 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. Please contact Michael Staten at 360-275-9374 if you have any questions, comments. or require additional information. Sincerely. Envirote h Engineering Michael Staten, P.E. Project Director Envirotech Engineering Midwest Solutions Geotechnical Report Ph. 360-275-9374 Page 9 of 9 290 NE State Route 300 Fax: 360-275-4789 Belfair, Washington June 16.2018 APPENDIX A TEST PIT LOCATION PLAN SCALE, 1 INCH = 50 FEE 0 25 0 200FT± TPIO �II T N G TP2 LL- to XISTIN ❑USE TP3 e ST PROJECT LOCATION C❑MMERCIAL DEVELOPMENT GEOTECHNICAL REPORT 290 NE STATE ROUTE 300 PARCEL 12329-42-00020 MASON COUNTY WASHING? N ENGINEER, ENVIROTECH ENGINEERING LEGEND PO Box 984 BELFAIR, WASHINGTON 98528 360-275-9374 TPle TEST PIT TEST PIT LOCATI❑N PLAN APPENDIX B SOIL INFORMATION i �I I TEST PIT LOG TEST PIT NUMBER TP-1 PROJECT: Commercial Property Geotechnical Report DATE OF LOG: 6/4/2018 PROJECT NO: 18116 LOGGED BY: MCS CLIENT: Dr. Peterson EXCAVATOR: N/A LOCATION: 290 NE State Route 300 DRILL RIG: None Mason County, Washington ELEVATION: N/A INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A SOIL STRATA, STANDARD PENETRATION TEST DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE AND TEST DATA DEPTH N 10 30 50 0 SM Dark brown, moist: SILTY SAND with organics. Topsoil T . . .. .. . . .. . . . . .. . . .. . .. . . . . . . . . Red and brown, moist, SILTY SAND with 2 gravel. Sand is medium. Gravel is well graded and subrounded. Low plasticity. `' SP-SM Light brown, moist, dense, POORLY 3 GRADED SAND and SILT with gravel. � Sand is medium. Gravel is fine and subrounded. No plasticity. 4 K' 5 Mottling .,: Excavation terminated at approximately 6 feet 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 indicative of the entire site. TEST PIT LOG TEST PIT NUMBER TP-2 PROJECT: Commercial Property Geotechnical Report DATE OF LOG: 6/4/2018 PROJECT NO: 18116 LOGGED BY: MCS CLIENT: Dr. Peterson EXCAVATOR: N/A LOCATION: 290 NE State Route 300 DRILL RIG: None Mason County. Washington ELEVATION: N/A INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A SOIL STRATA, STANDARD PENETRATION TEST DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE AND TEST DATA DEPTH N 10 30 50 0 SM Dark brown, moist, SILTY SAND with organics. Topsoil 1 Red and brown, moist, SILTY SAND with gravel. Sand is medium. Gravel is well graded and subrounded. Low plasticity. 2 SP-SM Light brown, moist, dense, POORLY 3 GRADED SAND and SILT with gravel. Sand is medium Gravel is fine and subrounded. No plasticity. 4 Excavation terminated at approximately 4 feet 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 indicitive of the entire site. TEST PIT LOG TEST PIT NUMBER TP-3 PROJECT: Commercial Property Geotechnical Report DATE OF LOG: 6/4/2018 PROJECT NO: 18116 LOGGED BY: MCS CLIENT: Dr. Peterson EXCAVATOR: N/A LOCATION: 290 NE State Route 300 DRILL RIG: None Mason County, Washington ELEVATION: N/A INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A SOIL STRATA, STANDARD PENETRATION TEST DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE AND TEST DATA DEPTH N 10 30 50 0 SM Dark brown, moist, SILTY SAND with organics. Topsoil 1 Red and brown, moist, SILTY SAND with 2 .; gravel. Sand is medium. Gravel is well - graded and subrounded. Low plasticity. 3 4 ;:... SP Light brown, moist, dense, POORLY GRADED SAND and with gravel and some silt. Sand is medium. Gravel is well 5 - graded and subrounded. No plasticity. Excavation terminated at approximately 6 feet 7 8 9 10 No Groundwater Encountered ENVIROTECH ENGINEERING This information pertains only to this bonng and should not be Geotechnical Engineering interpreted as being indicative of the entire site. Map Unit Description: Saxon silt loam, 5 to 15 percent slopes—Mason County,Washington Mason County, Washington Sa—Saxon silt loam, 5 to 15 percent slopes Map Unit Setting National map unit symbol: 2hmw Elevation: 0 to 200 feet Mean annual precipitation: 70 inches Mean annual air temperature: 43 degrees F Frost-free period: 100 to 120 days Farmland classification. Farmland of statewide importance Map Unit Composition Saxon and similar soils, 100 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Saxon Setting Landform: Escarpments terraces Parent material: Glaciolacustrine deposits with a mantle of volcanic ash Typical profile H1 - 0 to 3 inches: silt loam H2- 3 to 9 inches: silt loam H3- 9 to 60 inches: silt loam Properties and qualities Slope: 5 to 15 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 (0.20 to 0.57 in/hr) Depth to water table. About 18 to 23 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Very high (about 12.3 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated). 3e Hydrologic Soil Group: C/D Forage suitability group: Soils with Moderate Limitations (G002XN602WA) Natural Resources Web Soil Survey 6/16/2018 Conservation Service National Cooperative Soil Survey Page 1 of 2 Map Unit Description: Saxon silt loam, 5 to 15 percent slopes—Mason County,Washington Hydric soil rating: No Data Source Information Soil Survey Area: Mason County, Washington Survey Area Data: Version 13, Sep 7, 2017 Natural Resources Web Soil Survey 6/16/2018 �'�' Conservation Service National Cooperative Soil Survey Page 2 of 2