Loading...
HomeMy WebLinkAboutAttachment B_Geotechnical Report Geologically Hazardous Areas Report Maplewood Driving Range Restoration 4050 SE Maple Valley Road Renton, WA 98058 Baumwelt, PLLC 919 MLK Way Tacoma, WA 98405 Attn: Derrick Eberle, PLA, ASLA Prepared For: July 31, 2024 Project No. 24-2203 Baumwelt, PLCC 919 MLK Way Tacoma, WA 98405 Attn: Derrick Eberle, PLA, ASLA Regarding: Geologically Hazardous Areas Report Maplewood Driving Range Restoration 4050 SE Maple Valley Road Renton, WA 98058 Dear Mr. Eberle, As requested, GeoTest Services, Inc. [GeoTest] is pleased to submit the following report summarizing the results of our Geologically Hazardous Areas evaluation for the proposed driving range restoration work that is proposed at the above-referenced property in Renton, Washington (see Vicinity Map, Figure 1). This report has been prepared in general accordance with the terms and conditions established in our services agreement dated July 5th, 2024, and authorized by yourself. GeoTest appreciates the opportunity to provide geotechnical services on this project and look forward to assisting you during the construction phase. Should you have any further questions regarding the information contained within the report, or if we may be of service in other regards, please contact the undersigned. Respectfully, GeoTest Services, Inc. Jeff Vanfossen Harrison Simons, L.E.G. Geotechnical Technician Geotechnical Project Manager Enclosed: Geologically Hazardous Areas Report 7.31.2024 TABLE OF CONTENTS PURPOSE AND SCOPE OF SERVICES .....................................................................................................1 PROJECT DESCRIPTION .......................................................................................................................1 SITE CONDITIONS ...............................................................................................................................1 Surface Conditions ................................................................................................................................... 2 General Geologic Conditions .................................................................................................................... 3 Web Soil Survey........................................................................................................................................ 5 Aerial Photo Review ................................................................................................................................. 5 Bare Earth Imagery Review ...................................................................................................................... 8 GEOLOGICALLY HAZARDOUS AREAS ...................................................................................................9 Steep Slope Types .................................................................................................................................... 9 Landslide Hazards ................................................................................................................................... 10 Erosion Hazards ...................................................................................................................................... 10 Seismic Hazards ...................................................................................................................................... 11 Coal Mine Hazards, ................................................................................................................................ 11 CONCLUSIONS AND RECOMMENDATIONS ........................................................................................ 12 Geologically Hazardous Areas Mitigation .............................................................................................. 12 USE OF THIS REPORT ........................................................................................................................ 13 REFERENCES .................................................................................................................................... 14 GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 1 July 31, 2024 Project No. 24-2203 PURPOSE AND SCOPE OF SERVICES The purpose of this evaluation is to establish general site conditions from which conclusions and recommendations pertaining to project design can be formulated. Our scope of services includes the following tasks: • Perform a visual reconnaissance of the proposed development site and immediate vicinity to observe existing site topographic and surficial geologic conditions. • Provide a summary of site conditions observed at the site during our visit, and a summary of the regional surface conditions based on available documentation. • Provide an assessment of the geologically hazardous areas in accordance with Renton Municipal Code section 4-3-050A through 4-3-050N that are present and provide mitigative measures, as applicable, for the hazards on the subject property. PROJECT DESCRIPTION GeoTest understands that the existing driving range at the Maplewood Golf Course will undergo restoration to repair areas that have undergone minor settlement. Site improvements are specifically expected to consist of the placement of new crushed rock base material and the placement of new synthetic turf surfacing. Improvement is also expected to include some limited fence restoration work on fences which encompass the driving range facility. However, it is our understanding that fence posts and foundations associated with the planned fence improvements are existing structures and will not be impacted by the planned site improvements. Ground surface improvements to the existing, roughly 132,000 square foot facility is expected to require about 283 cubic yards of crushed surfacing material to fill in and repair areas which have demonstrated settlement. It is expected that existing stormwater management structures, consisting of a series of catch basins, will be preserved and implemented into the improved site conditions. Existing fill material removal is not expected as part of the planned improvements. SITE CONDITIONS This section includes a description of the general site conditions observed at the project site and during the review of the available documentation relevant to the subject property. Interpretations of site conditions are based on the results and review of available information, site reconnaissance, and previous experience in the project vicinity. GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 2 July 31, 2024 Project No. 24-2203 Surface Conditions A Geotechnical Technician visited the project area on July 12th, 2024, to observe existing surficial geologic and surface conditions on and adjacent to the subject area. The driving range is located at the Maplewood Golf Course within the city limits of Renton, Washington. The subject area is bound to the south by Maple Valley Highway, and well vegetated gold course property to its east and west. The Cedar River travels through the golf course to the southeast of the driving range and relatively tall slopes exist immediately to the north. Image 1. The existing driving range at Maplewood Golf Course during our site visit. Image taken using a Mavic 2 Pro drone facing south on July 12th, 2024. The existing surface of the driving range contains degraded turf and surficial gravelly fill materials. Several catch basins were observed across the existing driving range surface. Additionally, the driving range is encompassed by chain link fencing with wood board fasteners and tall protective netting with posts. The site supports a two-story structure along the southeastern extent of the driving range and contains hitting stalls on both stories. Other public, one to two story structures bound the driving range along its northwestern margin while an asphalt paved access and parking area extends along the western margin of the driving range. Overall, the driving range contains relatively low angle topography across much of its extent and exhibits about 10 to 15 feet of vertical relief over its roughly 630-foot length. However, immediately to the north / northeast of the range, intermittently steep slopes extend up from about 95 feet above sea level (ASL) in elevation to over 320 feet ASL over a distance of roughly 640 feet, resulting in about 225 feet of vertical relief. At the time of our site visit, the slopes to the north / northeast of the driving range were densely vegetated with various large deciduous GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 3 July 31, 2024 Project No. 24-2203 and coniferous trees as well as thick, low-lying vegetation that largely restricted our access. Where observed, larger trees appeared to demonstrate vertically oriented tree trunk geometry. GeoTest did not observe consistently downslope, or upslope leaning vegetation, exposed soils or other obvious signs of recent or insipient slope instability from our observation points along the toe of these slopes. Other than within the Cedar River and the various ponds the exist across the course, no surface water or seepage was observed on-site at the time of our site visit. General Geologic Conditions GeoTest obtained pertinent geologic information for the project site from the Geologic map of the Renton quadrangle, King County, Washington (Mullineaux, D.R., 1965). According to this publication, surficial geologic deposits along the base of the valley (and majority of the subject area), adjacent to the Cedar River, are mapped as Alluvium (Unit Qac). Furthermore, where stream channels outlet from steep channelized topography (such as the northern corner of the subject area), numerous Alluvial Fans exist, and existing soils are mapped as Alluvium (Unit Qas). The slopes immediately north/northeast of the project site are mapped as a sequence of deposits of mass wasting processes (unit Qmc), Undifferentiated deposits (map unit Qu), Ground moraine deposits (map unit Qgt), and Recessional stratified drift (map unit Qpa). These units are described in detail below. Image 2. The existing driving range mapped as predominantly Alluvium (map unit Qas and Qac) with a small portion of Mass Wasting Deposits (map unit Qmc) within the referenced geologic map, Geologic map of the Renton quadrangle, King County, Washington (Mullineaux, D.R., 1965). Approximate footprint of the driving range illustrated with a red box. GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 4 July 31, 2024 Project No. 24-2203 Alluvium (Unit Qac) – Sand and gravel deposited by the Cedar River and associated thin beds of silt, clay, and peat mostly at edges of fan shaped fill in Duwamish Valley. The maximum thickness of this unit in the Duwamish Valley can be more than 100 feet. Alluvium (Unit Qas) – Mostly sand with some silt and gravel deposited by small streams; generally thin. This unit is mapped where other published geologic resources map Alluvial Fan deposits and exist where confined channels extending from the adjacent upland topography become unconfined along valley margins. Deposits of mass wasting processes (Unit Qmc) – Colluvium, consists of internally deformed deposits of mass flowage, small block landslide, and alluvium of small intermittent streams. Present on nearly all steep slopes; mapped only where relatively thick and continuous. Maximum known thickness is about 40 feet. Mapped deposits generally form wet, unstable ground. Undifferentiated deposits (Unit Qu) – Includes three or more till sheets, glaciofluvial sand and gravel, glaciolacustrine clay and sand, and non glacial sand, glay, and thin peat, exposed mostly along Cedar River and Duwamish Valleys. Ground Moraine Deposits (Unit Qgt) – Mostly thin ablation till over lodgement till, deposited by Puget glacial lobe. Lodgement till generally compact coherent, unsorted mixture of sand, silt, clay and gravel; commonly termed hardpan. Ablation till is similar but much less compact and coherent. Unit is highly variable in thickness between about 2 and 30 feet thick. Recessional stratified drift (Unit Qpa) – Outwash along Cedar River valley; sandy pebble-and- cobble gravel in easternmost terraces, grades to interbedded sand and gravel at Renton, and to sand at north edge of quadrangle. According to the Washington Department of Natural Resources Washington Geologic Information Portal, the northern end of the driving range lies atop pro-historic landslide deposits. These deposits extend across the slopes which bound the site to the north / northeast. Additionally, according to the same resource, an alluvial fan landform is mapped where the unnamed creek exits channelized topography onto the Cedar River flood plain, just northwest of the subject area. More broadly, many large prehistoric landslides and relatively small alluvial fan deposits are mapped along the marginal slopes of the Cedar River Valley to the east and west of the project site. Lastly, at a distance of about 2.75 miles to the northeast, a strand of the Seattle Fault is mapped along May Creek. The Seattle Fault zone is composed of a series of east trending thrust faults that have recurrence intervals of about 200 to 12,000 years and are thought to be capable of producing up to about a 7.2 magnitude earthquake (Anderson, M.L., 2024). GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 5 July 31, 2024 Project No. 24-2203 Web Soil Survey According to the United States Department of Agriculture (USDA) Natural Resource Conservation Service (NRSC) Web Soil Survey website, the soils across the majority of the subject area are classified as Puyallup fine sandy loam, while the soils in the northeastern most corner are mapped as Mixed alluvial land. Please refer to Table 1 for a summary of the soil parameters found on the USDA Web Soil Survey. Erosion factors (K) indicate the susceptibility of soils to sheet and rill erosions by water. The factor K is one of six contributors used in the Universal Soil Loss Equation (USLE) and in the Revised Universal Soil Loss Equations (RUSLE) that help predict the average annual rate of soil loss by sheet and rill erosion. The estimates are based on percentages of organic matter, silt and sand, soil structure and saturated hydraulic conductivity (Ksat). Values of K range from 0.02 to 0.69, the higher the value, the more susceptible the soil is to sheet and rill erosion by water. The Puyallup fine sandy loam and mixed alluvial land soils present on the project site are considered to present high and moderate susceptibility to erosion according to their assigned K-values. However, based on the nature of the planned site improvements, we expect that erosion can be managed with conventional best management practices during construction. Aerial Photo Review We reviewed historic and recent aerial photos of the subject property from 1936 to 2024 to determine if there has been recent significant landslide activity within the vicinity of the project Table 1 - USDA Web Soil Survey Soil Classifications Map Unit Symbol Py Ma Map Unit Name Puyallup fine sandy loam Mixed alluvial land Approximate Site Location Southwestern majority Northeastern corner Soil Description Ashy fine sandy loam over very fine sandy loam over sand Sand over fine sand over loamy fine sand Landform Terraces, Floodplains NA Parent Material Alluvium NA Land Capability Classification 3w 4w Erosion K Factor, Whole Soil 0.43 .20 GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 6 July 31, 2024 Project No. 24-2203 site (Images 3 through 5). Aerial photos were obtained from the King County Parcel Viewer through the KCGIS Center. Other than the incremental development of single-family residences and infrastructure as well as the associated thinning of once existing vegetation, the subject property vicinity, and subject slopes, appear to have existed in a similar state over the duration of the reviewed images. Slopes within the subject property appear to have been densely vegetated over the reviewed duration of time. Please note that the aerial photos may not fully depict actual surface conditions due to the tree canopy and/or other vegetation possibly obscuring the ground surface. Image 3 - 1936 historical Image of the subject property accessed from the King County Parcel Viewer. The approximate driving range footprint is outlined in red. GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 7 July 31, 2024 Project No. 24-2203 Image 4 - 2007 historical Image of the subject property accessed from the King County Parcel Viewer. The approximate driving range footprint is outlined in red. Image 5 - 2021 historical Image of the subject property accessed from the King County Parcel Viewer. The approximate driving range footprint is outlined in red. GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 8 July 31, 2024 Project No. 24-2203 Bare Earth Imagery Review GeoTest reviewed bare earth imagery of the site vicinity, subject site, and its slopes that was acquired in 2021 and accessed from the Department of Natural Resources Washington LIDAR Portal website. Image 6 – Hillshade image derived from King County West 2021 DTM Hillshade LIDAR data. The approximate driving range footprint is outlined in red. Based on our review, evidence of a large global landslide is present to the northeast of the project site. Specific evidence includes a generally scalloped ridge crest, nested head scarps, side scarps and hummocky accumulations of materials along the base of the subject slopes. Hummocky material accumulations extend into the northeastern most portion of the subject area and currently support several holes for the existing golf course northeast of the subject area. Similar instances of slope instability and associated mass wasting deposits can also be seen to the east of the site along the northern margin of the Cedar River. Basal slope erosion produced by active river channel migration is a common trigger mechanism and/or contributing factor to global slope instability. From a contemporary standpoint, the Cedar River is located along the southern margin of the Cedar River Valley and was not actively eroding the slopes adjacent (to the northeast) to the existing driving range at the time these images were taken in 2021 (or during our site visit in 2024). Please note that not all signs of insipient slope instability can be observed in the bare earth imagery review due to imagery resolution and scale (refer to the Bare Earth Imagery, Figure 3). GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 9 July 31, 2024 Project No. 24-2203 GEOLOGICALLY HAZARDOUS AREAS According to the Renton Municipal Code (RMC) Chapter 11, section 4-11-070, Geologic Hazards are defined as areas which may be prone to one or more of the following conditions: erosion, flooding, landslides, coal mine hazards, or seismic activity. In Chapter 3 section 4-3-050 Critic(5)(A-I), RMC specifically goes on to define Steep Slope Hazards, Landslide Hazards, Erosion Hazards, Seismic Hazards, Coal Mine Hazards, Protected Slopes and Sensitive Slopes. Potential geologic hazards and their relevance to the project site are discussed in detail within the following sections of this report in accordance with Renton Municipal Code Chapter 4, section 4-3-050(A-N). Steep Slope Types According to RMC section 4-3-050(5)(a) steep slopes fall into two categories, Sensitive Slopes and Protected Slopes, as discussed below. Sensitive Slopes (RMC 4-3-050(a)(i): A hillside, or portion thereof, characterized by: • (a) an average slope of twenty five percent (25%) to less than forty percent (40%) as identified in the City of Renton Steep Slope Atlas or in a method approved by the City; or • (b) an average slope of forty percent (40%) or greater with a vertical rise of less than fifteen feet (15') as identified in the City of Renton Steep Slope Atlas or in a method approved by the City; • (c) abutting an average slope of twenty five percent (25%) to forty percent (40%) as identified in the City of Renton Steep Slope Atlas or in a method approved by the City. This definition excludes engineered retaining walls. Protected Slopes (RMC 4-3-050(a)(ii)): A hillside, or portion thereof, characterized by an average slope of forty percent (40%) or greater grade and having a minimum vertical rise of fifteen feet (15') as identified in the City of Renton Steep Slope Atlas or in a method approved by the City. Based on the RMC code definitions presented above, the northernmost portion of the subject area is considered to contain Sensitive Slopes because this portion of the site abuts slopes which demonstrate slopes between 25 and 40 percent. Additionally, the off-site slopes to the north/northeast are considered Protected Slopes because of their total vertical relief and demonstrated slope inclinations (Bare Earth Imagery, Figure 3). GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 10 July 31, 2024 Project No. 24-2203 Landslide Hazards According to RMC section 4-3-050(5)(b) Landslide Hazard areas fall into four categories, as discussed below. • Low Landslide Hazard (LL): Areas with slopes less than fifteen percent (15%). • Medium Landslide Hazard (LM): Areas with slopes between fifteen percent (15%) and forty percent (40%) and underlain by soils that consist largely of sand, gravel or glacial till. • High Landslide Hazards (LH): Areas with slopes greater than forty percent (40%), and areas with slopes between fifteen percent (15%) and forty percent (40%) and underlain by soils consisting largely of silt and clay. • Very High Landslide Hazards (LV): Areas of known mapped or identified landslide deposits Based on the information discussed in this report, and as shown in the attached Bare Earth Imagery exhibit, Figure 3, most of the on property subject area displays inclinations of less than 15 percent, and as such, are considered to present “Low Landslide Hazard” per RMC. However, the northern most portion of the project site and off-property steeply sloped areas to the northeast of the subject area are considered to present “High Landslide Hazard” based on slope inclination and “Very High Landslide Hazards” as a result of the mapped landslide deposits that exist in these areas. Due to the limited nature of the planned site improvements, it is GeoTest’s opinion that the work will not increase or decrease the risks that are present as a result of the existing, Landslide Hazards, Sensitive and Protected Slopes any more than the existing conditions do. Erosion Hazards According to RMC section 4-3-050(5)(c) Erosion Hazard areas fall into two categories, as discussed below. • Low Erosion Hazard (EL): Areas with soils characterized by the Natural Resource Conservation Service (formerly U.S. Soil Conservation Service) as having slight or moderate erosion potential, and a slope less than fifteen percent (15%) • High Erosion Hazard (EH): Areas with soils characterized by the Natural Resource Conservation Service (formerly U.S. Soil Conservation Service) as having severe or very severe erosion potential, and a slope more than fifteen percent (15%). As previously discussed, the mapped site soils are considered moderately to highly susceptible to sheet and rill erosion. Furthermore, the driving range itself does not contain slope inclinations which exceed 15 percent. As such, the project site is considered to present “Low Erosion Hazard”. Assuming the following recommendations are implemented during construction, we anticipate that erosion may be managed during construction. GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 11 July 31, 2024 Project No. 24-2203 • All grading activities for construction will need to incorporate Best Management Practices (BMPs) for erosion control in compliance with current City of Renton codes and standards. • Proper drainage controls have a significant effect on erosion. All collected stormwater should be directed to the existing, permitted stormwater collection system. • All areas disturbed by construction practices should be vegetated or otherwise protected to limit the potential for erosion as soon as practical during and after construction. In addition to the preceding recommendations, typical erosion control measures during construction will be required. These measures can include a rocked construction entrance or downslope silt fencing, depending on the regulations of the governing jurisdiction. Seismic Hazards According to RMC section 4-3-050(5)(d) Seismic Hazard areas fall into two categories, as discussed below. • Low Seismic Hazard (SL): Areas underlain by dense soils or bedrock. These soils generally have site classifications of A through D, as defined in the International Building Code, 2012. • High Seismic Hazard (SH): Areas underlain by soft or loose, saturated soils. These soils generally have site classifications E or F, as defined in the International Building Code, 2012. The subject area is underlain by alluvial (and mass wasting) soil deposits and is located within a flood plain setting along the Cedar River. Additionally, according to the Washington Geologic Information Portal, the site is considered to present moderate to high liquefaction susceptibility. As such, the project site, in our opinion is considered a High Seismic Hazard area. However, based on the nature of the planned improvements, no specific mitigations are recommended to address this potential hazard. Please note that this is a grading project and that no new above ground structures are planned. Coal Mine Hazards, According to RMC section 4-3-050(5)(e) Coal Mine Hazard areas fall into three categories, as discussed below. • Low Coal Mine Hazards (CL): Areas with no known mine workings and no predicted subsidence. While no mines are known in these areas, undocumented mining is known to have occurred • Medium Coal Mine Hazards (CM): Areas where mine workings are deeper than two hundred feet (200') for steeply dipping seams, or deeper than fifteen (15) times the GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 12 July 31, 2024 Project No. 24-2203 thickness of the seam or workings for gently dipping seams. These areas may be affected by subsidence. • High Coal Mine Hazard (CH): Areas with abandoned and improperly sealed mine openings and areas underlain by mine workings shallower than two hundred feet (200') in depth for steeply dipping seams, or shallower than fifteen (15) times the thickness of the seam or workings for gently dipping seams. These areas may be affected by collapse or other subsidence Based on our review of the City of Renton Sensitive Areas, Coal Mine Hazard Map (January 25, 2023), the project site is not underlain by known mine workings. Thus, the project site is considered to present Low Coal Mine Hazards per RMC. Based on the lack of known mine related workings below the site and the nature of the planned site improvements, we do not recommend specific mitigations be implemented into the planned project to address this potential hazard. CONCLUSIONS AND RECOMMENDATIONS The subject property presents (Low, High and Very High) Landslide Hazard), Sensitive and Protected Slopes, Low Erosion Hazard, High Seismic Hazard, and Low Coal Mine Hazard as discussed in detail above. However, the subject property supports a pre-existing, legally constructed golf course and driving range facility as well as access roadways which serve to provide access to the existing development. The intent of the proposed improvements is to renovate the existing driving range through the placement of new crushed rock materials, the placement of new turf surfaces (in areas currently occupied by turf) and some limited improvement of supporting, above grade infrastructure (nets, lights etc.,). Provided that the limited recommendations presented in the erosion hazard section of this report are implemented, it is GeoTest’s opinion that the proposed improvements will not negatively impact any of the of the geologically hazardous areas that currently exist on or adjacent to the subject property. Although these hazards do present risks to the project site, it is GeoTest’ s opinion that the proposed construction activities will not increase the levels of risk posed by the geologically hazardous areas above what already exist at the project site. Geologically Hazardous Areas Mitigation Based on our analysis of the information discussed in this report, it is our opinion that the proposed development conforms with RMC section 4-3-050F(a)(ii). Specifically, it is our opinion that the proposed improvements: • Will not increase the threat of the geological hazard to adjacent or abutting properties beyond pre-development conditions; and. • Will not adversely impact other critical areas; and. GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 13 July 31, 2024 Project No. 24-2203 • The development can be safely accommodated on the site. Furthermore, in accordance with RMC section 4-3-050M(3)(b), it is our opinion that the proposed development: • Hazard shall be reduced to a level equal to, or less than, the pre-development hazard. • Risk of personal injury resulting from the alteration shall be appropriately minimized; and • Does not propose to remove areas of existing native vegetation, and thus, no additional planting should be required. USE OF THIS REPORT GeoTest Services, Inc. has prepared this report for the exclusive use of Baumwelt, PLLC, as well as their clients and design consultants for specific application to the proposed driving range improvements located at 4050 SE Maple Valley Road in Renton, WA. Use of this report by others is at the user’s sole risk. This report is not applicable to other site locations. Our services are conducted in accordance with accepted practices of the geotechnical engineering profession; no other warranty, express or implied, is made as to the professional advice included in this report. Our site visit is representative of the dates and the locations observed during our visit. It is not warranted that these conditions are representative of conditions at other locations and times. The analyses, conclusions, and recommendations contained in this report are based on a reconnaissance-level site visit and a review of previously published USGS geological information for the site. If variations in conditions are encountered during construction that differs from those contained within this report, GeoTest should be allowed to review the recommendations and, if necessary, make revisions. If there is a substantial lapse of time between submission of this report and the start of construction, or if conditions change due to construction operations at or adjacent to the project site, we recommend that we review this report to determine the applicability of the conclusions and recommendations contained herein. The earthwork contractor is responsible to perform all work in conformance with all applicable WISHA/OSHA regulations. GeoTest Services, Inc. is not responsible for job site safety on this project, and this responsibility is specifically disclaimed. Attachments: Figure 1 Vicinity Map Figure 2 Site Plan Figure 3 Bare Earth Imagery Attached Report Limitations and Guidelines for Use (4 Pages) GeoTest Services, Inc. Maplewood Driving Range Restoration, Renton, WA 14 July 31, 2024 Project No. 24-2203 REFERENCES Anderson, M. L., Blakely, R. J., Wells, R. E., & Dragovich, J. D. (2024). Deep Structure of Siletzia in the Puget Lowland: Imaging an Obducted Plateau and Accretionary Thrust Belt With Potential Fields. Retrieved 06 February 2024, from https://doi.org/10.1029/2022TC007720 Mullineaux, D.R., 1965, Geologic map of the Renton quadrangle, King County, Washington, U.S. Geological Survey, Geologic Quadrangle Map GQ-405, 1:24,00 Renton Municipal Code, Washington. Retrieved July, 2024, from https://www.codepublishing.com/WA/Renton/#!/Renton04/Renton0403/Renton0403050.html#4-3-050G King County Parcel Viewer. King County, WA 2024. Accessed from https://kingcounty.gov/en/legacy/services/gis/Maps/terms-of-use.aspx United States Geological Survey. U.S Quaternary Faults Website. USGS Geologic Hazards Science Center, Golden, Colorado. Accessed from https://usgs.maps.arcgis.com/apps/webappviewer/index.html?id=5a6038b3a1684561a9b0aadf88412fcf USDA Web Soil Survey. (2017, August 21). Retrieved July 2024, from https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx. Washington State Department of Natural Resources - Online Web Services. Washington Geologic Information Portal. Retrieved in July 2024. Washington Lidar Portal. (n.d). Retrieved December 2023, from https://lidarportal.dnr.wa.gov. Date:Scale: Figure By:Project MAPLEWOOD DRIVING RANGE RESTORATION 4050 SE MAPLE VALLEY ROAD RENTON,WASHINGTON 24-2203 1 7-22-2024 JV As Shown VICINITY MAP PROJECT LOCATION MMaapp RReeffeerreenncceedd ffrroomm QQGGIISS 33..3344..55--PPrriizzrreenn Date:Scale: Figure By:Project MAPLEWOOD DRIVING RANGE RESTORATION 4050 SE MAPLE VALLEY ROAD RENTON,WASHINGTON 24-2203 2 7-22-2024 HS As Shown Site Plans Date:Scale: Figure By:ProjectDATASOURCE(S): MAPLEWOOD DRIVING RANGE RESTORATION 4050 SE MAPLE VALLEY ROAD RENTON,WASHINGTON 24-2203 3 7-22-2024 HS As Shown BARE EARTH IMAGERYELEVATION,SLOPE,AND HILLSHADE:DERIVEDFROM KINGCOUNTY WEST_2021LIDARSURVEY BY WASHINGTONLIDARPORTALUSINGQGIS MAPPEDLANDSLIDE ANDFAN DEPOSITS:DERIVED FROMWASHINGTON STATELANDSLIDE INVENTORY DATABASE2023 1 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) REPORT LIMITATIONS AND GUIDELINES FOR ITS USE1 Subsurface issues may cause construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such risks, you can manage them. The following information is provided to help: Geotechnical Services are Performed for Specific Purposes, Persons, and Projects At GeoTest our geotechnical engineers and geologists structure their services to meet specific needs of our clients. A geotechnical engineering study conducted for a civil engineer may not fulfill the needs of an owner, a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geotechnical engineering report is unique, prepared solely for the client. No one except you should rely on your geotechnical engineer who prepared it. And no one – not even you – should apply the report for any purpose or project except the one originally contemplated. Read the Full Report Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotechnical Engineering Report is Based on a Unique Set of Project-Specific Factors GeoTest’s geotechnical engineers consider a number of unique, project-specific factors when establishing the scope of a study. Typical factors include: the clients goals, objectives, and risk management preferences; the general nature of the structure involved its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless GeoTest, who conducted the study specifically states otherwise, do not rely on a geotechnical engineering report that was: •not prepared for you, •not prepared for your project, •not prepared for the specific site explored, or •completed before important project changes were made. 2 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: • the function of the proposed structure, as when it’s changed, for example, from a parking garage to an office building, or from a light industrial plant to a refrigerated warehouse, • elevation, configuration, location, orientation, or weight of the proposed construction, • alterations in drainage designs; or • composition of the design team; the passage of time; man-made alterations and construction whether on or adjacent to the site; or by natural alterations and events, such as floods, earthquakes or groundwater fluctuations; or project ownership. Always inform GeoTest’s geotechnical engineer of project changes – even minor ones – and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed. Subsurface Conditions Can Change This geotechnical or geologic report is based on conditions that existed at the time the study was performed. Do not rely on the findings and conclusions of this report, whose adequacy may have been affected by: the passage of time; by man-made events, such as construction on or adjacent to the site; or by natural events, such as floods, earthquakes, or groundwater fluctuations. Always contact GeoTest before applying the report to determine if it is still relevant. A minor amount of additional testing or analysis will help determine if the report remains applicable. Most Geotechnical and Geologic Findings are Professional Opinions Our site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoTest’s engineers and geologists review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ – sometimes significantly – from those indicated in your report. Retaining GeoTest who developed this report to provide construction observation is the most effective method of managing the risks associated with anticipated or unanticipated conditions. 3 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) A Report’s Recommendations are Not Final Do not over-rely on the construction recommendations included in this report. Those recommendations are not final, because geotechnical engineers or geologists develop them principally from judgment and opinion. GeoTest’s geotechnical engineers or geologists can finalize their recommendations only by observing actual subsurface conditions revealed during construction. GeoTest cannot assume responsibility or liability for the report’s recommendations if our firm does not perform the construction observation. A Geotechnical Engineering or Geologic Report may be Subject to Misinterpretation Misinterpretation of this report by other design team members can result in costly problems. Lower that risk by having GeoTest confer with appropriate members of the design team after submitting the report. Also, we suggest retaining GeoTest to review pertinent elements of the design teams plans and specifications. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having GeoTest participate in pre-bid and preconstruction conferences, and by providing construction observation. Do not Redraw the Exploration Logs Our geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors of omissions, the logs included in this report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable; but recognizes that separating logs from the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give contractors the complete geotechnical engineering report, but preface it with a clearly written letter of transmittal. In that letter, consider advising the contractors that the report was not prepared for purposes of bid development and that the report’s accuracy is limited; encourage them to confer with GeoTest and/or to conduct additional study to obtain the specific types of information they need or prefer. A pre-bid conference can also be valuable. Be sure contractors have sufficient time to perform additional study. Only then might you be in a position to give contractors the best information available, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. 4 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) In addition, it is recommended that a contingency for unanticipated conditions be included in your project budget and schedule. Read Responsibility Provisions Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering or geology is far less exact than other engineering disciplines. This lack of understanding can create unrealistic expectations that can lead to disappointments, claims, and disputes. To help reduce risk, GeoTest includes an explanatory limitations section in our reports. Read these provisions closely. Ask questions and we encourage our clients or their representative to contact our office if you are unclear as to how these provisions apply to your project. Environmental Concerns Are Not Covered in this Geotechnical or Geologic Report The equipment, techniques, and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study. For that reason, a geotechnical engineering or geologic report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated containments, etc. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk management guidance. Do not rely on environmental report prepared for some one else. Obtain Professional Assistance to Deal with Biological Pollutants Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts biological pollutants from growing on indoor surfaces. Biological pollutants includes but is not limited to molds, fungi, spores, bacteria and viruses. To be effective, all such strategies should be devised for the express purpose of prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional biological pollutant prevention consultant. Because just a small amount of water or moisture can lead to the development of severe biological infestations, a number of prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of this study, the geotechnical engineer or geologist in charge of this project is not a biological pollutant prevention consultant; none of the services preformed in connection with this geotechnical engineering or geological study were designed or conducted for the purpose of preventing biological infestations.