APPENDIX E
GEOTECHNICAL STUDY
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Experience is the difference
GEOTECHNICAL STUDY REPORT
YOUNTVILLE COMMONS
6554 YOUNT STREET
YOUNTVILLE, CALIFORNIA
Project Number:
6860.022.PW.2
Prepared For:
Town of Yountville
6550 Yount Street
Yountville, California
Prepared By:
RGH Consultants
Santa Rosa Office Napa Office
3501 Industrial Drive, Suite A 1041 Jefferson Street, Suite 4 Santa Rosa, CA 95403 Napa, CA 94559
707-544-1072 707-252-8105
_______________________ _______________________
Jared J. Pratt Eric G. Chase
Principal Engineering Geologist Principal Geotechnical Engineer Project Manager
September 16, 2025
i
TABLE OF CONTENTS
INTRODUCTION....................................................................................................................................................1 SCOPE ................................................................................................................................................................... 2 STUDY ................................................................................................................................................................... 3 Site Exploration.......................................................................................................................................3 Exploratory Borings...................................................................................................................3 Cone Penetration Tests.............................................................................................................3 Shear Wave Velocity Measurements........................................................................................4 General......................................................................................................................................4 Infiltration..................................................................................................................................4 Laboratory Testing..................................................................................................................................4 SITE CONDITIONS .................................................................................................................................................5 General....................................................................................................................................................5 Geology ...................................................................................................................................................5 Landslides................................................................................................................................................5 Surface and Subsurface ..........................................................................................................................5 Western Structures...................................................................................................................5 Eastern Structures.....................................................................................................................6 Site Class .................................................................................................................................................6 Infiltration Testing...................................................................................................................................7 Corrosion Potential.................................................................................................................................7 Groundwater ..........................................................................................................................................7 Flooding...................................................................................................................................................7 DISCUSSION AND CONCLUSIONS.........................................................................................................................8 Seismic Hazards......................................................................................................................................8 Faulting and Seismicity..............................................................................................................8 Liquefaction...............................................................................................................................8 Western Structures Liquefaction..............................................................................................8 Eastern Structures Liquefaction................................................................................................9 Bearing Capacity Failure............................................................................................10 Lateral Spreading.......................................................................................................10 Settlement.................................................................................................................10 Densification............................................................................................................................10 Geotechnical Issues..............................................................................................................................10 General....................................................................................................................................10 Heterogeneous Fill ..................................................................................................................11 Weak Surface Soil....................................................................................................................11 Foundation, Slab and Pavement Support.................................................................11 On-Site Soil Quality .................................................................................................................11 Engineered Fill.........................................................................................................................11 Settlement...............................................................................................................................11 Surface Drainage.....................................................................................................................12 RECOMMENDATIONS.........................................................................................................................................12 Seismic Design ......................................................................................................................................12 Grading..................................................................................................................................................13 Site Preparation.......................................................................................................................13 Stripping ..................................................................................................................................13 Excavations..............................................................................................................................13 Fill Quality................................................................................................................................14 TABLE OF CONTENTS (cont’d)
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Import Fill ................................................................................................................................14 Fill Placement..........................................................................................................................15 Permanent Cut and Fill Slopes................................................................................................16 Wet Weather Grading.............................................................................................................16 Foundation Support..............................................................................................................................17 Spread Footings.......................................................................................................................18 Rigid Slabs................................................................................................................................18 Retaining Walls.....................................................................................................................................19 Foundation Support................................................................................................................20 Wall Drainage and Backfill ......................................................................................................20 Slab-On-Grade ......................................................................................................................................21 Swimming Pool .....................................................................................................................................21 Utility Trenches.....................................................................................................................................22 Pavements............................................................................................................................................22 Wet Weather Paving...............................................................................................................23 Geotechnical Drainage .........................................................................................................................23 Slab Underdrains.....................................................................................................................23 Maintenance.........................................................................................................................................24 Supplemental Services..........................................................................................................................24 Pre-Bid Meeting ......................................................................................................................24 Plan and Specifications Review...............................................................................................24 Construction Observation and Testing...................................................................................25 LIMITATIONS.......................................................................................................................................................26
APPENDICES
APPENDIX A - PLATES................................................................................................................... A-1 APPENDIX B - REFERENCES .......................................................................................................... B-1 APPENDIX C – SHEAR WAVE VELOCITY REPORTS ........................................................................ C-1 APPENDIX D - DISTRIBUTION .......................................................................................................D-1
INFORMATION ABOUT YOUR GEOTECHNICAL REPORT
INTRODUCTION
This report presents the results of our geotechnical study for the Yountville Commons project to be constructed on the old Yountville Elementary School campus located at 6554 Yount Street in Yountville, California. The property extends over 6.8 acres and previously operated as an elementary school. The Town of Yountville City Hall (Town Hall) is located on the southwest corner of the property and was previously part of the school. Two of the existing school buildings (Schmitt Hall and Yountville Fit) will remain and will not be significantly modified. The site location is shown on Plate 1, Appendix A.
We understand it is planned to transform the former Yountville Elementary School site into a community center and housing development. There are five new structures planned on the western portion of the property, including a greenhouse at the north property line, executive briefing center just north of the Town Hall, two 2-story structures, and one 3-story structure. These structures will have slab-on-grade floors and will be supported on spread footings. Residential units are planned for these structures, and there may be a live work component on the first floor. There are 24 structures planned for the eastern portion of the property. These will consist of residential units, a pet services facility, a laundromat, and a food hub. We anticipate the structures will have slab-on-grade floors. The laundromat will have a residential lounge and a public roof deck. Some of the residential structures will be two stories and some will be three stories. A pool and hot tub are planned to east Schmitt Hall. Parking is planned on the northern side of the project with access off Yount Street. Auto access will be provided by a new asphaltpaved driveway on the northern side of the property. We understand that permeable pavers and TrueGrid are being considered for the parking areas. The existing parking lot on the south side of the property, east of the Town Hall, will be improved. Small retaining walls may be used where there are grade changes.
Walkways and community areas are planned.
Actual foundation loads are not known at this time. We anticipate the loads will be typical for the light to moderately heavy type of construction planned. Grading plans are not available, but we anticipate that the planned grading will be the minimum amount needed to construct level building pads and provide the building sites and paved areas with positive drainage and could include cuts and fills on the order of 1 to 3 feet.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
SCOPE
The purpose of our study, as outlined in our proposal dated June 10, 2025, was to generate geotechnical information for the design and construction of the project. Our scope of services included reviewing selected published geologic data pertinent to the site; evaluating the subsurface conditions with Cone Penetration Tests (CPTs), borings, laboratory tests, and shear wave velocity measurements; analyzing the field and laboratory data; and presenting this report with the following geotechnical information:
1. A brief description of the soil and groundwater conditions observed during our study;
2. A discussion of seismic hazards that may affect the proposed improvements; and
3. Conclusions and recommendations regarding:
a. Primary geotechnical engineering concerns and mitigating measures, as applicable; b. Site preparation and grading, including remedial grading of weak, porous, compressible soil and/or expansive surface soil;
c. Foundation type(s), design criteria, and estimated settlement behavior; d. Lateral loads for retaining wall design;
e. Support of concrete slabs-on-grade;
f. Preliminary pavement thickness based on our experience with similar soil and projects; g. Utility trench backfill;
h. Geotechnical engineering drainage improvements; and
i. Supplemental geotechnical engineering services.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
STUDY
Site Exploration
We reviewed our previous geotechnical studies in the vicinity and selected geologic references pertinent to the site. The geologic literature reviewed is listed in Appendix B.
Exploratory Borings
On July 24 and 25, 2025, we performed a geotechnical reconnaissance of the western portion of the site and explored the subsurface conditions by drilling four borings to depths ranging from about 23½ to 36½ feet. On July 25, 2025, we explored the subsurface conditions on the eastern portion of the site by drilling ten borings to depths ranging from about 5 to 5½ feet. The borings were drilled with a truck-mounted drill rig equipped with 6-inch diameter, solid stem and 8-inch diameter hollow stem augers at the approximate locations shown on the Exploration Plan, Plate 2. Our engineer located and logged the borings and obtained samples of the materials encountered for visual examination, classification, and laboratory testing.
Relatively undisturbed samples were obtained from the borings at selected intervals by driving a 2.43- inch inside diameter, split spoon sampler, containing 6-inch-long brass liners, using a 140-pound hammer dropping approximately 30 inches. The sampler was driven 12 to 18 inches. The blows required to drive each 6-inch increment were recorded and the blows required to drive the last 12 inches, or portion thereof, were converted to equivalent Standard Penetration Test (SPT) blow counts for correlation with empirical data. Disturbed samples were also obtained at selected depths by driving a 1.375-inch inside diameter (2-inch outside diameter) SPT sampler, without liners or rings, using a 140-pound hammer dropping approximately 30 inches. The sampler was driven 12 to 18 inches, the blows to drive each 6-inch increment were recorded, and the blows required to drive the final 12 inches, or portion thereof, are provided on the boring logs. Disturbed samples were also obtained from the borings and placed in plastic bags.
Cone Penetration Tests
On July 25, 2025, we continued our geotechnical reconnaissance of the site and explored the subsurface conditions by pushing eight Cone Penetration Tests (CPTs) to depths of approximately 50 feet at the approximate locations shown on the Exploration Plan, Plate 2. The CPT method consists of pushing an instrumented cone, with the tip facing down, into the ground at a controlled rate. The CPT measures the resistance of the tip to penetration into the soil and the skin friction along a sleeve located slightly above the tip. These values are used to estimate various soil properties and determine their Normalized Soil Behavior Type using the methods of Robertson (1990). The CPT plots show their interpretation of the subsurface soil and groundwater conditions on the date and at the locations indicated. Subsurface conditions may vary at other locations and times.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Shear Wave Velocity Measurements
On July 23, 2025, we conducted two seismic surveys, one on the western portion of the property and one on the eastern portion of the property, each with one shear wave velocity line with twelve geophones at a spacing of around 20 feet, for total array lengths of around 220 feet, to generate information on the soil site class. The approximate locations of the shear wave velocity lines are shown on the Exploration Plan on Plate 2.
General
The boring, CPT, and shear wave velocity line locations were determined approximately by pacing their distance from features shown on the Exploration Plan and should be considered accurate only to the degree implied by the method used. The logs of the borings showing the materials encountered, groundwater conditions, converted blow counts, and sample depths are presented on Plates 3 through
16. The soil is described in accordance with the Unified Soil Classification System, outlined on Plate 17.
The plots of the CPTs showing the materials encountered are presented on Plates 18 through 25. The shear wave velocity report can be found in Appendix C.
The logs show our interpretation of the subsurface soil and groundwater conditions on the date and at the locations indicated. Subsurface conditions may vary at other locations and times. Our interpretation is based on visual inspection of soil samples, laboratory test results, and interpretation of drilling and sampling resistance. The location of the soil boundaries should be considered approximate. The transition between soil types may be gradual.
Infiltration
After drilling was complete, Borings B-4, B-5, and B-8 were converted to infiltration tests in order to measure infiltration rates on the soil. The results of our testing are presented in the Infiltration Testing section of this report.
Laboratory Testing
The samples were transported to our office and re-examined to verify soil classifications, evaluate characteristics, and assign tests pertinent to our analysis. Selected samples were laboratory tested to determine their classification (Atterberg Limits, percent of silt and clay), expansion potential (Expansion Index - EI), water content, dry density, and shear strength. The test results are presented on the logs and on Plates 26 through 31.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
SITE CONDITIONS
General
Napa County is located within the California Coast Range geomorphic province. This province is a geologically complex and seismically active region characterized by sub-parallel northwest-trending faults, mountain ranges and valleys. The oldest bedrock units are the Jurassic-Cretaceous Franciscan Complex and Great Valley sequence sediments originally deposited in a marine environment. Subsequently, younger rocks such as the Tertiary-age Sonoma Volcanics group, the Plio-Pleistocene-age Clear Lake Volcanics and sedimentary rocks such as the Guinda, Domengine, Petaluma, Wilson Grove, Cache, Huichica and Glen Ellen formations were deposited throughout the province. Extensive folding and thrust faulting during late Cretaceous through early Tertiary geologic time created complex geologic conditions that underlie the highly varied topography of today. In valleys, the bedrock is covered by thick alluvial soil.
Geology
Published geologic maps (Bezore et al., 2005) indicate the property is underlain by fan deposits (Qpf) from the Pleistocene epoch on the west half of the property, alluvium (Qha) from the Holocene epoch on the east half of the property, and a thin strip of alluvial fan deposits (Qf) from the late Pleistocene epoch towards the southern boundary of the property. The fan deposits, alluvium, and alluvial fan deposits are all shown to consist of sand, gravel, silt, and clay.
Landslides
The site is essentially flat and not located near hillsides. The nearest sloping conditions are approximately ½ mile to the southwest.
Surface and Subsurface
Western Structures
The western portion of the parcel extends over relatively level terrain. This area of the site is overlain with an asphalt-paved parking lot and playground in addition to concrete flatwork. Natural drainage consists of sheet flow over the ground surface that concentrates in man-made surface drainage elements such as gutters and storm drains.
In this area of the site, we found the pavement sections to generally consist of 1 to 4 inches of asphalt over 3 to 9 inches of aggregate base. These pavement sections are underlain by heterogeneous fill to depths of about ½ to 1½ feet. Heterogeneous fill is a material with varying density, strength, compressibility, and shrink-swell characteristics that often has an unknown origin and placement history.
The heterogeneous fill is underlain by sandy clay, silty sand, and clayey sand with varying amounts of gravel that extend to depths of about 6½ to 9 feet and are generally of lower strength to depths of 3 to 3½ feet. The sandy clay exhibits medium plasticity (LL = 31.4; PI = 13.2) and very low expansion potential (EI = 15). The silty sand exhibits high plasticity (LL = 64.2; PI = 31.9). The clayey sands exhibit medium to RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
high plasticity (LL = 36.1, 61.6; PI = 15.3, 32.5) and low expansion potential (44). These layers of nearsurface soil then transition to high plasticity clays that generally extend to depths of about 18½ to 29½ feet and contain occasional sand lenses. These clays are underlain predominantly by clayey sands that interbed with layers of clay. These alternating layers extend to the maximum depths explored in the western portion of the property (36½ feet). A detailed description of the subsurface conditions found in our borings in the western portion of the property is given on Plates 3 through 6, Appendix A.
Eastern Structures
The eastern portion of the site extends primarily over relatively level to gently sloping terrain. Hopper Creek runs parallel to the eastern boundary of the site. The vegetation consists of short seasonal grass in the sports fields and dog park and relatively young trees. Some portions of this area of the property are asphalt-paved such as the firetruck access road and the basketball courts. In general, the ground surface outside of paved areas is soft and spongy. This is a condition generally associated with weak, porous surface soil. Natural drainage consists of sheet flow over the ground surface that concentrates in manmade surface drainage elements such as storm drains or natural drainage elements like Hopper Creek.
Our borings in the vicinity of the eastern structures indicate that the portion of the site we studied is blanketed predominantly by clayey sand and sandy clay that are weak, porous, and compressible to depths of ½ to 1½ feet. Porous soil may appear hard and strong when dry but become weak and compressible as its moisture content increases towards saturation. These soils exhibit low to high plasticity (LL = 32.9, 35.1, 37.4, 49.5; PI = 11.2, 15.0, 13.3, 23.9) and low expansion potential (EI = 32, 26, 25, 45) and extend to depths of about 2 to 5 feet below the ground surface before the subsurface soils transition to high plasticity clays. Our CPTs show layers of very dense and stiff soil predominantly in the upper 2 to 15 feet. Below those layers, the subsurface stratigraphy consists primarily of clayey soil. A detailed descriptions of the subsurface conditions found in our borings and CPTs in the eastern portion of the property are given on Plates 7 through 16 and Plates 18 through 25, respectively, in Appendix A.
Site Class
RGH’s geophysical site evaluation included subsurface seismic imaging and earthquake ground shaking potential evaluation using Terēan’s VsSurf ReMi™ seismic data processing software. Seismic surveys were performed on the east and west halves of the property to determine the seismic site class per American Society of Civil Engineers (ASCE) 7-22, titled “Minimum Design Loads and Associated Criteria for Buildings and Other Structures” (2022) using the weighted-average soil shear wave velocity for the upper 100 feet (Vs100). The surveys were performed by recording active and/or ambient (passive) seismic sources. The seismic recording array for these surveys consisted of 12, 4.5 Hertz (Hz) geophones at 20 foot spacing, for a total survey length of 220 feet. Noise was generated by walking along the survey line during data acquisition and 12-pound hammer hits while ambient noise was generated from traffic along the nearby roads. The seismic data were acquired using a ReMiNode™ 2-12 channel seismograph, while data was processed using Terēan's ReMi™ software (terean.com/products). Survey results indicate a weightedaverage soil shear wave velocity for the upper 100 feet (Vs100) of 813 and 1,155 feet per second (ft/s) on the east and west halves of the site, respectively. This results in a designation of a Seismic Site Class D on the east half of the site and Seismic Site Class CD on the west half of the site according to Table 20.2-1 of ASCE 7-22. Detailed descriptions of the seismic surveys can be found in Appendix C.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Infiltration Testing
The infiltration tests consisted of extending a 2-inch diameter PVC pipe to a depth of about 5 feet. The pipe was sealed around the bottom so that water could not flow up the sides of the pipe. Water was then poured into the pipe and allowed to infiltrate for a minimum of 2 hours, which we define as the shortterm test. For the long-term test, we allowed water to infiltrate overnight. The volume of water that infiltrated for each measured time period was then divided by the time period to obtain the infiltration rate.
We ran a long-term test in B-4 from July 24 to 25, 2025 and short-term tests in B-5 and B-8 on July 25, 2025. The infiltration rate for Boring B-4 was determined as 0.0007 cubic centimeters per second. For Borings B-5 and B-8, the infiltration rates were determined as 0.0004 cubic centimeters per second.
Corrosion Potential
Mapping by the Natural Resources Conservation Service (2025) indicates that the corrosion potential of the near surface soil is moderate for uncoated steel and moderate for concrete. Performing corrosivity tests to verify these values was not part of our requested and/or proposed scope of work. Should the need arise, we would be pleased to provide a proposal to evaluate these characteristics.
Groundwater
On the west half of the site, free groundwater was first detected in our borings at depths ranging from 8½ to 28 feet below the ground surface at the time of drilling. On the east half of the site, free groundwater was detected in our CPTs at depths ranging from 7 to 31 feet below the ground surface immediately after the CPTs were pushed. Fluctuation in the groundwater level typically occurs because of a variation in rainfall intensity, duration and other factors such as flooding and periodic irrigation.
Flooding
Our review of the Federal Emergency Management Agency (FEMA) Flood Zone Map for Town of Yountville, California (No. 06055C0413E) dated September 26, 2008, indicates that the property is located within Zone “X,” an area determined to be outside the 500-year flood plain. Evaluation of flooding potential is typically the responsibility of the project civil engineer.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
DISCUSSION AND CONCLUSIONS
Seismic Hazards
Faulting and Seismicity
We did not observe landforms within the area that would indicate the presence of active faults, and the site is not within a current Alquist-Priolo Earthquake Fault Zone (Bryant and Hart, 2007). Therefore, we believe the risk of fault rupture at the site is low. However, the site is within an area affected by strong seismic activity and future seismic shaking should be anticipated at the site. It will be necessary to design and construct the proposed improvements in strict adherence with current standards for earthquakeresistant construction.
Liquefaction
Liquefaction is a rapid loss of shear strength experienced in saturated, predominantly granular soil below the groundwater level during strong earthquake ground shaking due to an increase in pore water pressure. The occurrence of this phenomenon is dependent on many complex factors including the intensity and duration of ground shaking, particle size distribution and density of the soil.
There are three potential consequences of liquefaction: bearing capacity failure, lateral spreading toward a free face (e.g. riverbank), and settlement. Bearing capacity failure is sudden and extreme settlement of foundations that typically occurs when the liquefied layer is relatively close (typically within two times the footing width, depending on the loads) to the bottom of the foundation. Lateral spreading can occur where continuous layers of liquefiable soil extend to a free face, such as a creek bank. The third potential consequence of liquefaction is settlement due to densification of the liquefied soil.
Western Structures Liquefaction
Granular soil was encountered at the site below the groundwater table. Therefore, we performed an analysis of the blow count data from our borings using the methods of Seed and Idriss (1982), Seed and others (1985), Youd and Idriss (2001), Idriss and Boulanger (2004), and Idriss and Boulanger (2008). These procedures normalize the blow counts to account for overburden pressure, rod length, hammer energy, and fines (percent of silt and clay) content. Once the blow counts are normalized and adjusted to a clean sand blow count, the cyclic resistance ratio (CRR) for each blow count is then determined using the same procedures referenced above. The CRR is compared to the cyclic stress ratio (CSR) induced by the earthquake. Calculating the CSR requires peak ground acceleration and design earthquake magnitude.
Peak ground acceleration (PGA) was determined using the methods in the 2025 California Building Code (CBC) and the American Society of Civil Engineers (ASCE) Standard 7-22, titled “Minimum Design Loads and Associated Criteria for Buildings and Other Structures” (2022). Using the OSHPD Seismic Design Maps website (https://seismicmaps.org), the site’s latitude and longitude of 38.4043°N and 122.3612°W, respectively, and a site soil Class of CD (Shear Wave Velocity report in Appendix C), the PGA for the site is
0.78g. Using this information, the CSR for a MM 7.5 earthquake at the site ranges from 0.46 to 0.71. The West Napa fault is most likely controlling the ground motions at the site. According to the Building Seismic Safety Council 2014 Event Set (BSSC, 2014) the West Napa fault is capable of a MM 6.97 earthquake.
Therefore, the CRR values at the site must be scaled to account for the difference between MM 6.97 and RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
MM 7.5. When the scaling factor for magnitude and confining stress corrections presented in Idriss and Boulanger (2004) are applied, the CRR values at the site do not exceed the CSR values, with a Factor of Safety greater than 1.25, for layers from about 2½ to 8½ feet and about 29½ to 33½ feet in boring B-1, from about 4½ to 6½ feet in boring B-2, from about 15 to 16½ feet and about 22 to 24 feet in boring B-3, and about 14 to 15 feet in boring B-4. When factoring in fines (percent silt and clay) contents greater than 30, Plasticity Indexes greater than 30, and the work of Seed and Others (2003), the layers about 10 feet in borings B-1 and B-2 have low susceptibility to liquefaction. Therefore, we judge that there is potential for liquefaction in the following layers: about 29½ to 33½ feet in boring B-1, about 15 to 16½ feet and about 22 to 24 feet in boring B-3, and about 14 to 15 feet in boring B-4.
Bearing Capacity Failure - Because the shallowest liquefiable layer is about 10 feet below the ground surface, we judge that the potential for bearing capacity failure for western structures is low.
Lateral Spreading – The liquefiable layers within this area are discontinuous. Therefore, we judge the potential for liquefaction-induced lateral spreading for the western structures.
Settlement - Potential settlement based on the blow count data and cyclic stress ratio were calculated using the methods of Ishihara and Yoshimine (1992). For liquefiable layers outlined above, we calculated total settlement ranging up to ½ inch with differential settlement on the order of ½ inch over a distance of about 100 feet.
Eastern Structures Liquefaction
Granular soil was encountered at the site below the groundwater table. Therefore, we analyzed the data from the eight CPTs performed at the site using the methods of Idriss and Boulanger (2014) and the CPT liquefaction analysis program CLiq. CPT soundings provide nearly continuous, repeatable measurements that provide a detailed profile of the soil (Robertson, 2015).
The Idriss and Boulanger (2014) method uses the soil measurements recorded by the cone to evaluate the potential for liquefaction and requires an earthquake magnitude and peak ground acceleration. Peak ground acceleration (PGA) was determined using the methods in the 2025 CBC and ASCE Standard 7-22 (2022). Using the OSHPD Seismic Design Maps website (https://seismicmaps.org), the site’s latitude and longitude of 38.4043°N and 122.3612°W, respectively, and a Site Class of D, the PGA for the site is 0.71g.
The West Napa fault is most likely controlling the ground motions at the site. According to the Building Seismic Safety Council Earthquake Scenario Event Set (BSSC, 2014) and the USGS Earthquake Scenario Map (available at
http://usgs.maps.arcgis.com/apps/webappviewer/index.html?id=14d2f75c7c4f4619936dac0d14e1e468 ), the West Napa fault is capable of a MM 6.97 earthquake.
Our review of the CPT data indicates that some soil layers are overconsolidated. The degree of consolidation of the soils impacts the Ic cutoff value used for the liquefaction analysis. This value is initially set at 2.6 but can be adjusted based on the actual soil conditions. We evaluated Ic cutoff values between
2.25 and 2.5 and selected the best fit Ic for each CPT. Based on the results of the CPT analysis, we judge that there is potential for liquefaction throughout the property. Our analysis found potentially liquefiable layers of variable thickness primarily from about 6 to 13 feet. These layers are generally thin, less than 12 inches thick and were not encountered in all CPTs. Additional relative thin (less than 6 inches thick) RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
liquefiable layers were encountered around 18 ½ feet in CPT-7 and 22 and 26 in CPT-2. An approximately 18-inch-thick layer was encountered at about 36 feet in CPT-2.
Bearing Capacity Failure – There are discontinuous liquefiable layers around 6 feet in some of the CPT’s.
Given that these layers are generally less than 12 inches thick and located at least 6 feet below the ground surface, we judge that the potential for bearing capacity failure is low.
Lateral Spreading – The potentially liquefiable layers at the site are discontinuous. The nearest free face in the vicinity of the eastern structures is the bank of Hopper Creek. The bottom of the creek is approximately 70 inches (less than 6 feet) below the top of the bank. The liquefiable layers are 6 feet below the ground surface and discontinuous. Therefore, we judge the potential for liquefaction-induced lateral spreading at the site is low.
Settlement - Potential settlement based on CPT data were calculated using the methods of Idriss and Boulanger (2014). For the layers encountered in the CPT’s, we calculated total settlement ranging from negligible up to ¾ inch with differential settlement on the order of ½ inch over a distance of 100 feet.
Densification
Densification is the settlement of loose, granular soil above the groundwater level due to earthquake shaking. Typically, granular soil that would be susceptible to liquefaction, if saturated, is susceptible to densification, if not saturated. Soils susceptible to liquefaction were not encountered above an earthquake analysis groundwater level of 5 feet below the ground surface. Therefore, we judge there is a low potential for densification to impact structures at the site.
Geotechnical Issues
General
Based on our study, we judge the proposed improvements can be built as planned, provided the recommendations presented in this report are incorporated into their design and construction. The primary geotechnical concerns during design and construction of the project are:
1. The presence of heterogeneous fill and weak, sometimes porous soil, that extend to depths of 3 ½ feet for the western structures and 1½ feet for the eastern structures;
2. The detrimental effects of uncontrolled surface runoff on the long-term satisfactory performance of structures given the erosion potential and porous nature of the surface soil; and
3. The strong ground shaking predicted to impact the site during the life of the project.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Heterogeneous Fill
Heterogeneous fills of unknown quality and unknown method of placement, such as those found at the site, can settle and/or heave erratically under the load of new fills, structures, slabs, and pavements.
Footings, slabs, and pavements supported on heterogeneous fill could also crack as a result of such erratic movements. Thus, where not removed by planned grading, the heterogeneous fill must be excavated and replaced as an engineered fill if it is to be used for structural support.
Weak Surface Soil
Weak surface soil, that is porous in some areas, such as that found at the site, appears hard and strong when dry but will lose strength rapidly and settle under the load of fills, foundations, slabs, and pavements as its moisture content increases and approaches saturation. The moisture content of this soil can increase as the result of rainfall, periodic irrigation or when the natural upward migration of water vapor through the soil is impeded by, and condenses under fills, foundations, slabs, and pavements. The detrimental effects of such movements can be reduced by strengthening the soil during grading. This can be achieved by excavating the weak soil and replacing it as properly compacted (engineered) fill.
Foundation, Slab and Pavement Support - After remedial grading, satisfactory foundation support for the structures can be obtained from spread footings or rigid slabs (mat slabs or PT slabs) bottomed on the engineered fill. Where spread footings are used for foundation support, interior slab-on-grade floors can be satisfactorily supported on the engineered fill. Exterior slabs and pavements can be satisfactorily supported on the engineered fill. Free retaining walls and site walls can be supported on spread footings gaining support from firm, native soil.
On-Site Soil Quality
We anticipate that, with the exception of organic matter and of rocks or lumps larger than 6 inches in diameter, the excavated material will be suitable for re-use as general fill and engineered fill within building, exterior slab, and pavement areas.
Engineered Fill
The engineered fill can consist of approved on-site soil or import materials with a low expansion potential.
The geotechnical engineer must approve the use of on-site soil as engineered fill during grading.
Settlement
If remedial grading is performed and the spread footings or rigid structural foundations are installed in accordance with the recommendations presented in this report, we estimate that post-construction differential settlement across each building will be about ½ inch. Earthquake-induced differential settlement is estimated to be on the order of ½ inch over a distance of 100 feet.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Surface Drainage
Surface runoff typically sheet flows over the ground surface but can be concentrated by the planned site grading, landscaping, and drainage. The surface runoff can pond against structures and seep into the slab rock. It will be necessary to divert surface runoff around improvements and provide positive drainage away from structures. This can be achieved by constructing the building pad several inches above the surrounding area and conveying the runoff into man-made drainage elements or natural swales that lead downgradient of the site.
RECOMMENDATIONS
Seismic Design
Seismic design parameters presented below are based on Section 1613 titled “Earthquake Loads” of the 2025 California Building Code (CBC). Based on Table 20.2-1 of American Society of Civil Engineers (ASCE) Standard 7-22, titled “Minimum Design Loads and Associated Criteria for Buildings and Other Structures” (2022) and the results of our seismic survey line (Appendix C), we have determined a Site Class of CD should be used for the western portion of the site and a Site Class of D should be used for the eastern portion of the site.
Using a site latitude and longitude of 38.4043°N and 122.3612°W, respectively, the United States Geological Survey web services (https://seismicmaps.org), and the procedures outlined in Section 20.2 of ASCE Standard 7-22 (2022), we calculated seismic motions using the measured shear wave velocities for Site Classes CD and D for the western structures and eastern structures,respectively. We recommend that the following seismic design criteria be used for applicable structures at the site designed using the 2025 CBC.
Western Structures
2025 CBC Seismic Criteria
Spectral Response Parameter Acceleration (g)
SS (0.2 second period) 2.020
S1 (1 second period) 0.760
SMS (0.2 second period) 2.130
SM1 (1 second period) 1.350
SDS (0.2 second period) 1.420
SD1 (1 second period) 0.900
RGH
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Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Eastern Structures
2025 CBC Seismic Criteria
Spectral Response Parameter Acceleration (g)
SS (0.2 second period) 2.020
S1 (1 second period) 0.760
SMS (0.2 second period) 1.960
SM1 (1 second period) 1.570
SDS (0.2 second period) 1.310
SD1 (1 second period) 1.050
Grading
Site Preparation
Areas to be developed should be cleared of vegetation and debris including that left by the removal of obsolete structures. Trees and shrubs that will not be part of the proposed development should be removed and their primary root systems grubbed. Cleared and grubbed material should be removed from the site and disposed of in accordance with County Health Department guidelines. We did not observe septic tanks, leach lines or underground fuel tanks during our study. Any such appurtenances found during grading should be capped and sealed and/or excavated and removed from the site, respectively, in accordance with established guidelines and requirements of the County Health Department. Voids created during clearing should be backfilled with engineered fill as recommended herein.
Stripping
Areas to be graded should be stripped of the upper few inches of soil containing organic matter. Soil containing more than two percent by weight of organic matter should be considered organic. Actual stripping depth should be determined by a representative of the geotechnical engineer in the field at the time of stripping. The strippings should be removed from the site, or if suitable, stockpiled for re-use as topsoil in landscaping.
Excavations
Following initial site preparation, excavation should be performed as recommended herein. Excavations extending below the proposed finished grade should be backfilled with suitable materials compacted to the requirements given below.
Within fill areas, whether there is a structure planned or not, and within building areas and interior slabon-grade areas, the heterogeneous fill and weak, porous, compressible surface soil should be excavated to within 6 inches of its entire depth, which is about 3 ½ feet in the western portion of the site and 1 ½ feet in the eastern portion of the site. The excavation of weak, compressible soil should also extend at RGH
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Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
least 12 inches below exterior slab and pavement subgrade where planned excavations do not completely remove the weak soil.
The excavation of weak, porous, compressible surface materials and heterogeneous fill should extend at least 5 feet beyond the outside edge of the exterior footings of the proposed buildings and 3 feet beyond the edge of exterior slabs and pavements. The excavated materials should be stockpiled for later use as compacted fill, or removed from the site, as applicable.
At all times, temporary construction excavations should conform to the regulations of the State of California, Department of Industrial Relations, Division of Industrial Safety or other stricter governing regulations. The stability of temporary cut slopes, such as those constructed during the installation of underground utilities, should be the responsibility of the contractor. Depending on the time of year when grading is performed, and the surface conditions exposed, temporary cut slopes may need to be excavated to 1½:1, or flatter. The tops of the temporary cut slopes should be rounded back to 2:1 in weak soil zones.
Fill Quality
All fill materials should be free of organic matter and rocks or lumps over 6 inches in diameter and must be approved by the geotechnical engineer prior to use. We judge the on-site soil is generally suitable for use as general fill and engineered fill within building, exterior slab, and pavement areas. The suitability of the on-site soil for use as engineered fill should be verified during grading.
Import Fill
In general, imported fill, if needed, should be select. Select fill should be free of organic matter, have a low expansion potential, and conform in general to the following requirements:
SIEVE SIZE PERCENT PASSING (by dry weight)
6 inch 100
4 inch 90 – 100
No. 200 10 – 60
Liquid Limit – 40 Percent Maximum
Plasticity Index – 15 Percent Maximum
R-value – 10 Minimum (pavement areas only)
Material not conforming to these requirements may be suitable for use as import fill; however, it shall be the contractor’s responsibility to demonstrate that the proposed material will perform in an equivalent manner. The geotechnical engineer should approve imported materials prior to use as compacted fill. The grading contractor is responsible for submitting, at least 72 hours (3 days) in advance of its intended use, samples of the proposed import materials for laboratory testing and approval by the soils engineer.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Fill Placement
The surface exposed by stripping and removal of heterogeneous fill and weak, compressible surface soil should be scarified to a depth of at least 6 inches, uniformly moisture-conditioned to near optimum, and compacted to at least 90 percent of the maximum dry density of the materials as determined by ASTM Test Method D-1557. Approved fill material should then be spread in thin lifts, uniformly moistureconditioned to near optimum and properly compacted. All structural fills, including those placed to establish site surface drainage, should be compacted to at least 90 percent relative compaction.
SUMMARY OF COMPACTION RECOMMENDATIONS
Area Compaction Recommendation (ASTM D-1557)
Preparation for areas to receive fill After preparation in accordance with this report, compact upper 6 inches to a minimum of 90 percent
relative compaction.
General fill (native or import) Compact to a minimum of 90 percent relative compaction.
Structural fill beneath buildings,
extending outward to 5' beyond
building perimeter
Compact to a minimum of 90 percent relative compaction.
Trenches Compact to a minimum of 90 percent relative compaction.
Compact the top 6 inches below vehicle pavement
subgrade to a minimum of 95 percent relative
compaction.
Retaining wall backfill Compact to a minimum of 90 percent relative compaction, but not more than 95 percent.
Pavements, extending outward to 3'
beyond edge of pavement
Compact upper 6 inches of subgrade to a minimum of 95
percent relative compaction.
Concrete flatwork and exterior slabs,
extending outward to 3' beyond edge
of slab
Compact subgrade to a minimum of 90 percent relative
compaction. Where subject to vehicle traffic, compact
upper 6 inches of subgrade to at least 95 percent relative compaction.
Aggregate Base Compact aggregate base to at least 95 percent relative compaction.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Permanent Cut and Fill Slopes
In general, cut and fill slopes should be designed and constructed at slope gradients of 2:1 (horizontal to vertical) or flatter, unless otherwise approved by the geotechnical engineer in specified areas. Where steeper slopes are required, retaining walls should be used. Fill slopes should be constructed by overfilling and cutting the slope to final grade. “Track walking” of a slope to achieve slope compaction is not an acceptable procedure for slope construction. The geotechnical engineer is not responsible for measuring the angles of these slopes.
Wet Weather Grading
Generally, grading is performed more economically during the summer months when the on-site soil is usually dry of optimum moisture content. Delays should be anticipated in site grading performed during the rainy season or early spring due to excessive moisture in on-site soil. Special and relatively expensive construction procedures, including dewatering of excavations and importing granular soil, should be anticipated if grading must be completed during the winter and early spring or if localized areas of soft saturated soil are found during grading in the summer and fall.
Open excavations also tend to be more unstable during wet weather as groundwater seeps towards the exposed cut slope. Severe sloughing and occasional slope failures should be anticipated. The occurrence of these events will require extensive clean up and the installation of slope protection measures, thus delaying projects. The general contractor is responsible for the performance, maintenance and repair of temporary cut slopes.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Foundation Support
Provided the heterogeneous fill and/or weak surface soil are removed by or strengthened by remedial grading as recommended herein, the proposed structures can be supported on continuous and isolated spread footings or rigid structural foundations that bottom on firm soil or engineered fill. Free standing retaining walls and walls can be supported on spread footings that bottom on firm, native soil or engineering fill. Foundation design criteria are presented in the tables below.
Foundation Design Criteria - Structures
Spread Footings
Minimum footing width (in) 12
Minimum footing depth (in)1 18
Allowable bearing pressure
Dead loads (psf) 2,000
Dead plus live loads (psf) 3,000
Total loads including wind and seismic (psf) 4,000
Lateral passive resistance 2, 3 350
Base friction coefficient 0.35
Rigid Slabs
Allowable bearing pressure
Dead loads (psf) 2,000
Dead plus live loads (psf) 3,000
Total loads including wind and seismic (psf) 4,000
Lateral passive resistance (pcf)2,3 350
Base friction coefficient 0.35
Modulus of subgrade reaction (k) (pci) 50
Differential settlement (inches) over 100 feet ½
1 Depth below lowest adjacent grade
2 Equivalent fluid pressure (pcf)
3 Ignore the upper 6 inches unless confined by concrete slabs or pavement Foundation Design Criteria – Free Standing Retaining Walls and Site Walls Spread Footings
Minimum footing width (in) 18
Minimum footing depth (in)1 18
Allowable bearing pressure
Dead loads (psf) 1,000
Dead plus live loads (psf) 1,500
Total loads including wind and seismic (psf) 2,000
Lateral passive resistance2, 3 150/320
Base friction coefficient 0.30
1 Depth below lowest adjacent grade
2 Equivalent fluid pressure (pcf)
3 150 pcf from 6 to 18 inches, 320 pcf below 18 inches
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Spread Footings
Spread footings should bottom on firm soil or engineered fill, as applicable. On sloping terrain, the footings should be stepped as necessary to produce level tops and bottoms. Footings should be deepened as necessary to provide at least 7 feet of horizontal confinement between the footing bottoms and the face of the nearest slope. The bottoms of all footing excavations should be thoroughly cleaned out or wetted and compacted using hand-operated tamping equipment prior to placing steel and concrete. This will remove the soil disturbed during footing excavations, or restore their adequate bearing capacity, and reduce post-construction settlement. Footing excavations should not be allowed to dry before placing concrete. If shrinkage cracks appear in soil exposed in the footing excavations, the soil should be thoroughly moistened to close all cracks prior to concrete placement. The moisture condition of the foundation excavations should be checked by the geotechnical engineer no more than 24 hours prior to placing concrete.
Rigid Slabs
A rigid slab can either be a post-tensioned (PT) slab or a mat slab. Because the near surface soils have low expansion potential, the rigid slabs do not need to be designed for expansive soil conditions. Therefore, PT or mat slabs can be designed using the same criteria as presented in the table above.
Rigid slabs typically have thickened areas at the edges and where heavier loads are anticipated, such as at columns. The bottoms of all excavations for thickened areas should be thoroughly cleaned out or wetted and compacted using hand-operated tamping equipment prior to placing steel and concrete. This will remove the soils disturbed during excavations, restore their adequate bearing capacity, and reduce post-construction settlements.
With the exception of thickened areas, mat slabs should be underlain with a capillary moisture break consisting of at least 4 inches of clean, free-draining crushed rock or gravel (excluding pea gravel) at least ¼-inch and no larger than ¾-inch in size. A vapor barrier should be incorporated into the mat slab design in all areas where moisture-sensitive floor coverings, coatings, underlayments, adhesives, moisture sensitive goods, humidity-controlled environments, or climate-cooled environments are anticipated initially, or in the future. Vapor barrier should consist of a minimum 15 mil extruded polyolefin plastic (no recycled content or woven materials permitted); permeance as tested before and after mandatory conditioning (ASTM E1745 Section 7.1 and Sub-paragraphs 7.1.1 – 7.1.5): less than 0.1 perms [grains/(ft2 per hour in Hg)] and comply with the ASTM E1745 class A requirements. The vapor barrier should also meet paragraphs 8.1 and 9.3 of ASTM E1745; subsequent documentation should be provided by the vapor barrier manufacturer. Install vapor barrier in accordance with ASTM E1643, including proper perimeter seal. Rigid slabs should be provided with an underdrain system. The installation of this subdrain system is discussed in the “Geotechnical Drainage” section.
Structural elements that are attached to the structure but have their own foundation should not be used or should be founded on the rigid slab. Exterior flatwork and concrete walkway subgrades should be underlain by at least 12 inches of engineered fill and be pre-swelled by soaking prior to installation of the walkway. In addition, concrete walkways should be cast separate from the rigid slab to allow differential settlement to occur without distressing the walkway; reinforced to reduce cracks; and grooved to induce cracking in a non-obtrusive manner.
RGH
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Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
The Post-Tensioning Institute states “Consideration should be given to ‘artificial’ effects, such as planter units adjacent to structural bearing areas. Tree roots can be a serious problem and cause volume reduction in limited areas, thus causing distress to the slab foundation. Trees that are planted closer to the foundation than half their ultimate height can be expected to cause significant differential movement.”
Retaining Walls
Retaining walls constructed at the site must be designed to resist lateral earth pressures plus additional lateral pressures that may be caused by surcharge loads applied at the ground surface behind the walls.
Retaining walls free to rotate (yielding greater than 0.1 percent of the wall height at the top of the backfill) should be designed for active lateral earth pressures. If walls are restrained by rigid elements to prevent rotation, they should be designed for “at rest” lateral earth pressures.
Retaining walls should be designed to resist the following earth equivalent fluid pressures (triangular distribution):
EARTH EQUIVALENT FLUID PRESSURES
Loading Condition Pressure
(pcf)
Additional Seismic
Pressure (pcf)*
for
Western Structures
Additional Seismic
Pressure (pcf)*
for
Eastern Structure
Active - Level Backfill 42 16 15
Active - Sloping Backfill 3:1 or Flatter 53 44 36
At Rest - Level Backfill 63 0** 0**
* If required
**Per Lew, Sitar, Al Atik, Pourzanjani, and Hudson (2010)
These pressures do not consider additional loads resulting from adjacent foundations or other loads. If these additional surcharge loadings are anticipated, we can assist in evaluating their effects. Where retaining wall backfill is subject to vehicular traffic, the walls should be designed to resist an additional surcharge pressure equivalent to two feet of additional backfill.
Retaining walls will yield slightly during backfilling. Therefore, walls should be backfilled prior to building on, or adjacent to, the walls. Backfill against retaining walls should be compacted to at least 90 and not more than 95 percent relative compaction. Over-compaction or the use of large compaction equipment should be avoided because increased compactive effort can result in lateral pressures higher than those recommended above.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Foundation Support
Retaining walls should be supported on spread footings or the rigid slabs designed in accordance with the recommendations presented in this report. Retaining wall foundations should be designed by the project civil or structural engineer to resist the lateral forces set forth in this section.
Wall Drainage and Backfill
Retaining walls should be backdrained as shown below. The backdrains should consist of 4-inch diameter, rigid perforated pipe embedded in Class 2 permeable material. The pipe should be PVC Schedule 40 or ABS with SDR 35 or better, and the pipe should be sloped to drain to outlets by gravity. The top of the pipe should be at least 8 inches below lowest adjacent grade. The Class 2 permeable material should extend to within 1½ feet of the surface. The upper 1½ feet should be backfilled with compacted soil to exclude surface water. Expansive soil should not be used for wall backfill. Where expansive soil is present in the excavation made to install the retaining wall, the excavation should be sloped back 1:1 from the back of the footing or grade beam. The ground surface behind retaining walls should be sloped to drain.
Where migration of moisture through retaining walls would be detrimental, retaining walls should be waterproofed.
Retaining Wall
Drain Rock
(See Note 1)
4" Perforated Pipe
(See Note 2)
Finished Floor
12"
Min Drain Rock or Compacted
Backfill ( See note 3)
1:1 Slope (See Note 4)
18" Min
Compacted non-expansive soil to
exclude surface water
Not to Scale
Drain rock should meet the requirements for Class 2 Permeable Material, Section 68, State of California “Caltrans” Standard Specification, latest edition. Drain rock should be placed to approximately threequarters the height of the retaining wall.
Pipe should conform to the requirements of Section 68 of State of California “Caltrans” Standards, perforations placed down, sloped at 1% for gravity flow to outlet or sump with automatic pump. The pipe invert should be located at least 8 inches below the lowest adjacent finished surface.
During construction the contractor should use appropriate methods such as temporary bracing and/or light compaction equipment to avoid overstressing the walls. Non-expansive soils to be used as backfill.
Slope excavation back at a 1:1 gradient from the back of footing where expansive materials are exposed.
Notes:
1. 2.
3. 4.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Slab-On-Grade
Provided grading is performed in accordance with the recommendations presented herein, slabs should be underlain by firm soil and/or engineered fill. Slab-on-grade subgrade should be rolled to produce a dense, uniform surface. The slabs should be underlain with a capillary moisture break consisting of at least 4 inches of clean, free-draining crushed rock or gravel (excluding pea gravel) at least ¼-inch and no larger than ¾-inch in size. Interior slabs subject to vehicular traffic may be underlain by Class 2 aggregate base.
The use of Class 2 aggregate base should be reviewed on a case-by-case basis. Class 2 aggregate base can be used for slab rock under exterior slabs. Interior area slabs should be provided with an underdrain system. The installation of this subdrain system is discussed in the “Geotechnical Drainage” section.
Slabs should be designed by the project civil or structural engineer to support the anticipated loads, reduce cracking and provide protection against the infiltration of moisture vapor. A vapor barrier should be incorporated into the floor slab design in all areas where moisture-sensitive floor coverings, coatings, underlayments, adhesives, moisture sensitive goods, humidity-controlled environments, or climatecooled environments are anticipated initially, or in the future. Vapor barrier should consist of a minimum 15 mil extruded polyolefin plastic (no recycled content or woven materials permitted); permeance as tested before and after mandatory conditioning (ASTM E1745 Section 7.1 and Sub-paragraphs 7.1.1 –
7.1.5): less than 0.1 perms [grains/(ft2 per hour in Hg)] and comply with the ASTM E1745 Class A requirements. The vapor barrier should also meet paragraphs 8.1 and 9.3 of ASTM E1745; subsequent documentation should be provided by the vapor barrier manufacturer. Install vapor barrier in accordance with ASTM E1643, including proper perimeter seal.
Swimming Pool
The pool bottom should be supported on firm native soils. Based on the sidewall conditions encountered, the pool walls should be designed for a minimum lateral earth equivalent fluid pressure of 60 pounds per cubic foot (pcf). The pool bottom should be provided with a drainage blanket consisting of 12 inches of ¾- inch crushed rock. This drainage blanket should extend across the entire bottom of the pool excavation.
In addition, the pool should be provided with a method for releasing built-up pressure due to groundwater in the event the pool is emptied. This can be achieved by outletting the drain blanket to a planned discharge area or by providing the pool bottom with a pressure relief valve. The use of the pressure relief system should be outlined in the user’s manual for the pool.
Grading for decking surrounding the pool should be performed in accordance with the recommendations provided in this report for exterior concrete slabs-on-grade. Perimeter decking should not be attached directly to the pool walls. The decking should be free to move independently of the pool.
These recommendations assume that the pool will not incorporate settlement sensitive features, such as a vanishing edge. If such features are planned, we should be contacted to provide specific recommendations for that condition.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Utility Trenches
The shoring and safety of trench excavations is solely the responsibility of the contractor. Attention is drawn to the State of California Safety Orders dealing with “Excavations and Trenches.” Unless otherwise specified, on-site, inorganic soil may be used as utility trench backfill. Where utility trenches support pavements, slabs and foundations, trench backfill should consist of aggregate baserock.
The baserock should comply with the minimum requirements in Caltrans Standard Specifications, Section 26 for Class 2 Aggregate Base. Trench backfill should be moisture-conditioned as necessary and placed in horizontal layers not exceeding 8 inches in thickness, before compaction. Each layer should be compacted to at least 90 percent relative compaction as determined by ASTM Test Method D-1557. The top 6 inches of trench backfill below vehicle pavement subgrades should be moisture-conditioned as necessary and compacted to at least 95 percent relative compaction. Jetting or ponding of trench backfill to aid in achieving the recommended degree of compaction should not be attempted.
Pavements
Based on our study, we believe the near-surface soil will have a low to moderate supporting capacity, after proper compaction, when used as a pavement subgrade. Because of potential variation in the onsite soil, we selected an R-value of 10 for use in pavement design calculations. Based on the assumed Rvalue, we have computed pavement sections for Traffic Indices (TI) ranging from 5.0 to 7.0 in the table below. The project engineer should choose the pertinent (TI) for this project.
PAVEMENT SECTIONS
TI
ASPHALT
CONCRETE
(feet)
CLASS 2
AGGREGATE BASE
(feet)
7.0 0.30 1.30
6.0 0.25 1.05
5.0 0.25 0.85
Pavement thicknesses were computed using the Caltrans Highway Design Manual and are based on a pavement life of 20 years. These recommendations are intended to provide support for traffic represented by the indicated Traffic Indices. They are not intended to provide pavement sections for heavy concentrated construction storage or wheel loads such as forklifts, parked truck-trailers and concrete trucks or for post-construction concentrated wheel loads such as self-loading dumpster trucks.
In areas where heavy construction storage and wheel loads are anticipated, the pavements should be designed to support these loads. Support could be provided by increasing pavement sections or by providing reinforced concrete slabs. Alternatively, paving can be deferred until heavy construction storage and wheel loads are no longer present. Loading areas for self-loading dumpster trucks should be provided with reinforced concrete slabs.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Prior to placement of aggregate base, the upper 6 inches of the pavement subgrade soil should be scarified, uniformly moisture-conditioned to near optimum, and compacted to at least 95 percent relative compaction to form a firm, non-yielding surface. Aggregate base materials should be spread in thin layers, uniformly moisture-conditioned, and compacted to at least 95 percent relative compaction to form a firm, non-yielding surface. The materials and methods used should conform to the requirements of the Town of Yountville and the current edition of the Caltrans Standard Specifications, except that compaction requirements should be based on ASTM Test Method D-1557. Aggregate used for the base course should comply with the minimum requirements specified in Caltrans Standard Specifications, Section 26 for Class 2 Aggregate Base.
Wet Weather Paving
In general, the pavements should be constructed during the dry season to avoid the saturation of the subgrade and base materials, which often occurs during the wet winter months. If pavements are constructed during the winter, a cost increase relative to drier weather construction should be anticipated. Unstable areas may have to be overexcavated to remove soft soil. The excavations will probably require backfilling with imported crushed (ballast) rock. The geotechnical engineer should be consulted for recommendations at the time of construction.
Geotechnical Drainage
Surface water should be diverted away from slopes, foundations, and edges of pavements. Surface drainage gradients should slope away from building foundations in accordance with the requirements of the CBC or local governing agency. Where a gradient flatter than 2 percent for paved areas and 4 percent for unpaved areas is required to satisfy design constraints, area drains should be installed with a spacing no greater than about 20 feet.
Roofs should be provided with gutters, and the downspouts should be connected to conduits (glued Schedule 40 PVC or ABS with SDR of 35 or better) that discharge well away from foundations and onto paved areas, erosion resistant natural drainages, or into the site’s storm drain system. Roof downspouts and surface drains must be maintained entirely separate from the slab underdrains recommended below.
Water seepage or the spread of extensive root systems into the soil subgrade of footings, slabs, or pavements could cause differential movements and consequent distress in these structural elements.
Landscaping should be planned with consideration for these potential problems.
Slab Underdrains
Where interior slab subgrades are less than 6 inches above adjacent exterior grade and where migration of moisture through the slab would be detrimental, slab underdrains should be installed to dispose of surface and/or groundwater that may seep and collect in the slab rock. Slab underdrains should consist of 6-inch-wide trenches that extend at least 6 inches below the bottom of the slab rock and slope to drain by gravity. The slab underdrain trenches should be spaced no further than 15 feet, both ways. Additional drain trenches should be installed, as necessary, to drain all isolated under slab areas. Four-inch diameter perforated pipe (SDR 35 or better) sloped to drain to outlets by gravity should be placed in the bottom of the trenches. Slab underdrain trenches should be backfilled to subgrade level with clean, free draining RGH
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Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
slab rock. An illustration of this system is shown below. If slab underdrains are not used, it should be anticipated that water will enter the slab rock, permeate through the concrete slab and ruin floor coverings.
SLAB UNDERDRAIN
Slab
Slab Rock
Slab Rock
4" min. Perforated
Plastic Pipe
6 SDR 35 or better "
(min)
6"
(min)
Perforated
Underslab
Drain Pipe
Solid Outlet Pipe to
Approved Outlet
Lateral @ 15-foot intervals
(both ways) and to drain all
isolated underslab areas
TYPICAL UNDERSLAB DRAIN PLAN
Maintenance
Periodic land maintenance will be required. Surface and subsurface drainage facilities should be checked frequently and cleaned and maintained as necessary or at least annually. A dense growth of deep-rooted ground cover must be maintained on all slopes to reduce sloughing and erosion. Sloughing and erosion that occurs must be repaired promptly before it can enlarge.
Supplemental Services
Pre-Bid Meeting
It has been our experience that contractors bidding on the project often contact us to discuss the geotechnical aspects. Informal contacts between RGH Consultants (RGH) and an individual contractor could result in incomplete or misinterpreted information being provided to the contractor. Therefore, we recommend a pre-bid meeting be held to answer any questions about the report prior to submittal of bids. If this is not possible, questions or clarifications regarding this report should be directed to the project owner or their designated representative. After consultation with RGH, the project owner or their representative should provide clarifications or additional information to all contractors bidding the job.
Plan and Specifications Review
Coordination between the design team and the geotechnical engineer is recommended to assure that the design is compatible with the soil, geologic and groundwater conditions encountered during our study.
RGH recommends that we be retained to review the project plans and specifications to determine if they are consistent with our recommendations. In the event we are not retained to perform this recommended review, we will assume no responsibility for misinterpretation of our recommendations.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Construction Observation and Testing
Prior to construction, a meeting should be held at the site that includes, but is not limited to, the owner or owner’s representative, the general contractor, the grading contractor, the foundation contractor, the underground contractor, any specialty contractors, the project civil engineer, other members of the project design team and RGH. This meeting should serve as a time to discuss and answer questions regarding the recommendations presented herein and to establish the coordination procedure between the contractors and RGH.
In addition, we should be retained to monitor all soil related work during construction, including, but not limited to:
• Site stripping, over-excavation, grading, and compaction of near surface soil; • Placement of all engineered fill and trench backfill with verification field and laboratory testing;
• Observation of all foundation excavations; and
• Observation of foundation and subdrain installations.
If, during construction, we observe subsurface conditions different from those encountered during the explorations, we should be allowed to amend our recommendations accordingly. If different conditions are observed by others, or appear to be present beneath excavations, RGH should be advised at once so that these conditions may be evaluated and our recommendations reviewed and updated, if warranted.
The validity of recommendations made in this report is contingent upon our being notified and retained to review the changed conditions.
If more than five years have elapsed between the submission of this report and the start of work at the site, or if conditions have changed because of natural causes or construction operations at, or adjacent to, the site, or a significant code change occurs, the recommendations made in this report may no longer be valid or appropriate. In such case, we recommend that we be retained to review this report and verify the applicability of the conclusions and recommendations or modify the same considering the time lapsed or changed conditions. The validity of recommendations made in this report is contingent upon such review.
These supplemental services are performed on an as-requested basis and are in addition to this geotechnical study. We cannot accept responsibility for items that we are not notified to observe or for changed conditions we are not allowed to review.
RGH
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Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
LIMITATIONS
This report has been prepared by RGH for the exclusive use of the Town of Yountville and their consultants as an aid in the design and construction of the proposed improvements described in this report.
The validity of the recommendations contained in this report depends upon an adequate testing and monitoring program during the construction phase. Unless the construction monitoring and testing program is provided by our firm, we will not be held responsible for compliance with design recommendations presented in this report and other addendum submitted as part of this report.
Our services consist of professional opinions and conclusions developed in accordance with generally accepted geotechnical engineering principles and practices. We provide no warranty, either expressed or implied. Our conclusions and recommendations are based on the information provided to us regarding the proposed construction, the results of our field exploration, laboratory testing program, and professional judgment. Verification of our conclusions and recommendations is subject to our review of the project plans and specifications, and our observation of construction.
The CPTs, borings, and shear wave velocity reports represent the subsurface conditions at the locations and on the date indicated. It is not warranted that they are representative of such conditions elsewhere or at other times. Site conditions and cultural features described in the text of this report are those existing at the time of our field exploration and may not necessarily be the same or comparable at other times.
The scope of our services did not include an environmental assessment or a study of the presence or absence of toxic mold and/or hazardous, toxic or corrosive materials in the soil, surface water, groundwater or air (on, below or around this site), nor did it include an evaluation or study for the presence or absence of wetlands. These studies should be conducted under separate cover, scope and fee and should be provided by a qualified expert in those fields.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Page A-1
APPENDIX A - PLATES
LIST OF PLATES
Plate 1 Site Location Map
Plate 2 Exploration Plan
Plates 3 through 16 Logs of Borings B-1 through B-14
Plate 17 Soil Classification Chart and Key to Test Data Plates 18 through 25 Logs of CPTs CPT-1 through CPT-8
Plates 26 through 28 Classification Test Data
Plates 29 through 31 Shear Strength Test Data
Reference: Mapline Scale: 1" = 2000'
Site
SITE LOCATION MAP PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
1 7
9 PRELIMINARY - NOT FOR CONSTRUCTION
CHECK DRAW
DESIG
DATE
JOB N
SHEET Printed on Recycled Paper Please Continue the Cycle T 3 COMPACT COMPACT COMPACT COMPACT COMPACT COMPACT COMPACT COMPACT PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
EXPLORATION PLAN
2 Reference: Google Earth Overlayed with “Yountville Commons” by RSA+ dated 9/21/2025, Sheet TM3 Scale: 1" =100' B-3
Boring Location and Number
EXPLANATION
CPT-3
CPT Location and Number
100 0 100 feet
B-1
B-2
B-3
B-4
B-9
B-8
B-10
B-14
B-13
B-12
B-5
B-6
B-7
B-11
CPT-3
CPT-6
CPT-5
CPT-4
CPT-1
CPT-2
CPT-8
CPT-7
Shear Wave Velocity Lines
LOG OF BORING B-1
3 Date
Drilled 7/24/2025
Drilling
Method Hollow-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level 8 1/2 feet
Logged By PLB
Drill Bit
Size/Type 8 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Modified California, SPT
Project Manager EGC
Total Depth
of Borehole 35 1/2 feet
Approximate
Surface Elevation Top of Pavement
Hammer
Data 140 lb., 30" drop
31.4 61.6
50.5 15
36.3 39.3
99.5 92.9
86.1 20.9
25.1 36.4
MATERIAL DESCRIPTION
2" ASPHALT
GRAY BROWN AND GRAY CLAYEY SAND (SC),
dense, dry (Fill)
BROWN SANDY CLAY WITH GRAVEL (CL), stiff,
moist
BROWN CLAYEY SAND (SC), loose to medium
dense, moist
LIGHT BROWN CLAY (CH), stiff, moist
GRAY BROWN CLAY (CH), very stiff, moist
13.2 32.5
0 5
10 15
20 10
13 9
9 10
9 20
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-1 CONTINUED
3 Cont.
14.5 MATERIAL DESCRIPTION
GRAY BROWN CLAY (CH), very stiff, moist
GRAY CLAYEY SAND (SC), medium dense, moist to
wet
GRAY BROWN CLAY (CH), hard, wet
GRAY BROWN CLAYEY SAND WITH GRAVEL (SC),
dense, wet
Boring terminated at 35 1/2 feet
Groundwater encountered at 8 1/2 feet
25 30
35 40
45 20
19 17
31 PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-2
4 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level 9 feet
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s)
Modified California, No Recovery,
SPT
Project Manager EGC
Total Depth
of Borehole 23 1/2 feet
Approximate
Surface Elevation Top of Pavement
Hammer
Data 140 lb., 30" drop
31.4 64.2
61.1 MATERIAL DESCRIPTION
4" ASPHALT OVER 3" AGGREGATE BASE
GRAY BROWN GRAVEL WITH SAND (GP), medium
dense, dry (Fill)
BROWN SILTY SAND WITH GRAVEL (SM), medium
dense, moist
BROWN CLAY (CL), medium stiff, moist
LIGHT BROWN CLAY (CH), medium stiff, moist to wet
BROWN SANDY CLAY (CH), stiff, wet
BROWN SANDY CLAY (CL), medium stiff, wet
BROWN SANDY CLAY (CH), very stiff, wet
Boring terminated at 23 1/2 feet
Groundwater encountered at 9 feet
31.9 0
5 10
15 20
20 17
11 7
8 9
7 17
19 PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-3
5 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level 14 feet
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Modified California, SPT
Project Manager EGC
Total Depth
of Borehole 26 1/2 feet
Approximate
Surface Elevation Top of Pavement
Hammer
Data 140 lb., 30" drop
49.9 36.1 44
20.2 41.6
28.2 Su = 2,259 psf
103.0
104.8
93.8 84.8
22.0 21.1
26.6 34.1
MATERIAL DESCRIPTION
1" ASPHALT OVER 6" AGGREGATE BASE
BROWN CLAYEY SAND (SC), medium dense to
dense, moist
BROWN CLAY (CH), stiff, moist
BROWN CLAYEY SAND (SC), loose, wet
BROWN CLAY WITH SAND (CH), medium stiff, moist
to wet
BROWN CLAYEY SAND (SC), medium dense, wet
BROWN SANDY CLAY (CH), stiff, wet
15.3 0
5 10
15 20
14 35
17 9
10 6
19 15
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-3 CONTINUED
5 Cont.
MATERIAL DESCRIPTION
BROWN SANDY CLAY (CH), stiff, wet
Boring terminated at 26 1/2 feet
Groundwater encountered at 14 feet
25 30
35 40
45 14
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-4
6 Date
Drilled 7/24/2025
Drilling
Method Hollow-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level 28 feet
Logged By PLB
Drill Bit
Size/Type 8 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Modified California, SPT
Project Manager EGC
Total Depth
of Borehole 36 1/2 feet
Approximate
Surface Elevation Top of Pavement
Hammer
Data 140 lb., 30" drop
8 60
30.5 Su = 6,312.5 psf
Su = 3,756 psf
116.7
90.5 14.6
31.6 MATERIAL DESCRIPTION
2-1/2" ASPHALT OVER 9" AGGREGATE BASE
GRAY AND BROWN CLAYEY SAND WITH GRAVEL
(SC), medium dense, dry (Fill)
BROWN CLAYEY SAND (SC), medium dense to
dense, moist
BROWN CLAYEY SAND WITH GRAVEL (SC),
medium dense, moist
LIGHT BROWN CLAY (CH), stiff, moist
BROWN CLAYEY SAND WITH GRAVEL (SC),
medium dense, moist
LIGHT BROWN CLAY (CH), medium stiff to stiff, moist
BROWN SANDY CLAY (CH), very stiff, moist
0 5
10 15
20 19
38 28
13 14
8 9
16 PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-4 CONTINUED
6 Cont.
30.7 MATERIAL DESCRIPTION
BROWN SANDY CLAY (CH), very stiff, moist
BROWN CLAYEY SAND (SC), medium dense, moist
to wet
GRAY SAND WITH GRAVEL (SP), medium dense, wet
GRAY BROWN CLAYEY SAND WITH GRAVEL (SC),
dense, moist
Boring terminated at 36 1/2 feet
Groundwater encountered at 28 feet
25 30
35 40
45 20
27 28
32 PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-5
7 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level No Groundwater
Encountered
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Bulk
Project Manager EGC
Total Depth
of Borehole 5 feet
Approximate
Surface Elevation Existing Ground Surface
Hammer
Data 140 lb., 30" drop
MATERIAL DESCRIPTION
LIGHT BROWN CLAYEY SAND (SC), porous to 1 foot
BROWN CLAYEY GRAVEL WITH SAND (GC)
BROWN CLAYEY SAND (GC)
Boring terminates at 5 feet
No groundwater encountered
Infiltration test installed
0 5
10 15
20 PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-6
8 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level No Groundwater
Encountered
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Bulk
Project Manager EGC
Total Depth
of Borehole 5 feet
Approximate
Surface Elevation Existing Ground Surface
Hammer
Data 140 lb., 30" drop
35.1 32
MATERIAL DESCRIPTION
YELLOW BROWN SANDY CLAY (CL), porous to 6
inches
BROWN SANDY CLAY (CL)
Boring terminated at 5 feet
No groundwater encountered
15.0 0
5 10
15 20
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-7
9 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level No Groundwater
Encountered
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Bulk
Project Manager EGC
Total Depth
of Borehole 5 feet
Approximate
Surface Elevation Existing Ground Surface
Hammer
Data 140 lb., 30" drop
MATERIAL DESCRIPTION
YELLOW BROWN CLAYEY SAND WITH GRAVEL
(SC), porous to 6 inches
BROWN SANDY CLAY (CH)
Boring terminated at 5 feet
No groundwater encountered
0 5
10 15
20 PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-8
10 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level No Groundwater
Encountered
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Bulk
Project Manager EGC
Total Depth
of Borehole 5 1/2 feet
Approximate
Surface Elevation Existing Ground Surface
Hammer
Data 140 lb., 30" drop
49.5 45
MATERIAL DESCRIPTION
DARK BROWN CLAYEY SAND WITH GRAVEL (SC),
porous
BROWN SANDY CLAY (CL)
BROWN CLAYEY SAND WITH GRAVEL (SC)
Boring terminated at 5 1/2 feet
No groundwater encountered
23.9 0
5 10
15 20
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-9
11 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level No Groundwater
Encountered
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Bulk
Project Manager EGC
Total Depth
of Borehole 5 feet
Approximate
Surface Elevation Existing Ground Surface
Hammer
Data 140 lb., 30" drop
MATERIAL DESCRIPTION
BROWN SANDY CLAY (CL), porous to 6 inches
LIGHT BROWN CLAY WITH SAND (CH)
Boring terminated at 5 feet
No groundwater encountered
0 5
10 15
20 PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-10
12 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level No Groundwater
Encountered
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Bulk
Project Manager EGC
Total Depth
of Borehole 5 feet
Approximate
Surface Elevation Existing Ground Surface
Hammer
Data 140 lb., 30" drop
MATERIAL DESCRIPTION
BROWN SANDY CLAY WITH GRAVEL (CL), porous to
6-8 inches
DARK BROWN CLAY WITH SAND (CH)
Boring terminated at 5 feet
No groundwater encountered
0 5
10 15
20 PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-11
13 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level No Groundwater
Encountered
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Bulk
Project Manager EGC
Total Depth
of Borehole 5 feet
Approximate
Surface Elevation Existing Ground Surface
Hammer
Data 140 lb., 30" drop
37.4 25
MATERIAL DESCRIPTION
BROWN SANDY CLAY (CL), porous to 1 foot
Boring terminated at 5 feet
No groundwater encountered
13.3 0
5 10
15 20
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-12
14 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level No Groundwater
Encountered
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Bulk
Project Manager EGC
Total Depth
of Borehole 5 feet
Approximate
Surface Elevation Existing Ground Surface
Hammer
Data 140 lb., 30" drop
32.9 26
MATERIAL DESCRIPTION
YELLOW BROWN SANDY CLAY (CL), porous to 3
inches
DARK BROWN CLAY (CH)
Boring terminated at 5 feet
No groundwater encountered
11.2 0
5 10
15 20
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-13
15 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level No Groundwater
Encountered
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Bulk
Project Manager EGC
Total Depth
of Borehole 5 feet
Approximate
Surface Elevation Existing Ground Surface
Hammer
Data 140 lb., 30" drop
MATERIAL DESCRIPTION
YELLOW BROWN SANDY SILT WITH GRAVEL (ML),
porous to 3 inches
BROWN SANDY CLAY (CH)
Boring terminated at 5 feet
No groundwater encountered
0 5
10 15
20 PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF BORING B-14
16 Date
Drilled 7/24/2025
Drilling
Method Solid-Stem Auger
Drill Rig
Type B-53 Mobile Drill Rig
Groundwater Level No Groundwater
Encountered
Logged By PLB
Drill Bit
Size/Type 6 inch
Drilling
Contractor Pearson Drilling
Sampling
Method(s) Bulk
Project Manager EGC
Total Depth
of Borehole 5 feet
Approximate
Surface Elevation Existing Ground Surface
Hammer
Data 140 lb., 30" drop
MATERIAL DESCRIPTION
YELLOW BROWN CLAYEY SAND (SC), porous to 6
inches
BROWN SANDY CLAY (CH)
Boring terminated at 5 feet
No groundwater encountered
0 5
10 15
20 PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
SOIL CLASSIFICATION AND KEY TO TEST DATA
17 MATERIAL DESCRIPTION
1 2 3 4 5 6 7 8 9 10 11 12 13
COLUMN DESCRIPTIONS
1 Depth (feet): Depth in feet below the ground surface. 2 Sample Type: Type of soil sample collected at the depth interval shown.
3 Sampling Resistance, blows/ft: Number of blows to advance driven sampler one foot (or distance shown) beyond seating interval using the hammer identified on the boring log.
4 Graphic Log: Graphic depiction of the subsurface material encountered.
5 MATERIAL DESCRIPTION: Description of material encountered.
May include consistency, moisture, color, and other descriptive text.
6 Dry Density (pcf): Dry density, in pcf.
7 Water Content (%): Water content, percent.
8 % <#200 Sieve: % <#200 Sieve
9 PI, %: Plasticity Index, expressed as a water content. 10 LL, %: Liquid Limit, expressed as a water content.
11 Expansion Index (EI): Expansion Index (EI)
12 UC, ksf: Unconfined compressive strength, in kips per square foot. 13 REMARKS AND OTHER TESTS: Comments and observations
regarding drilling or sampling made by driller or field personnel. Su, psf: Undrained Shear Strength, in pounds per square foot (psf)
FIELD AND LABORATORY TEST ABBREVIATIONS
LL: Liquid Limit, percent
PI: Plasticity Index, percent
SA: Sieve analysis (percent passing No. 200 Sieve)
Su: Undrained Shear Strength, in pounds per square foot (psf)
MATERIAL GRAPHIC SYMBOLS
Asphaltic Concrete (AC)
Fat CLAY, CLAY w/SAND, SANDY CLAY (CH)
Lean CLAY, CLAY w/SAND, SANDY CLAY (CL)
Clayey GRAVEL (GC)
Poorly graded GRAVEL (GP)
SILT, SILT w/SAND, SANDY SILT (ML)
Clayey SAND (SC)
Silty SAND (SM)
Poorly graded SAND (SP)
TYPICAL SAMPLER GRAPHIC SYMBOLS
Bulk Sample
2.5-inch-OD Modified
California w/ brass liners
2-inch-OD unlined split
spoon (SPT)
OTHER GRAPHIC SYMBOLS
Water level (at time of drilling, ATD)
Water level (after waiting, AW)
Minor change in material properties within a
stratum
Inferred/gradational contact between strata
? Queried contact between strata
GENERAL NOTES
1: Soil classifications are based on the Unified Soil Classification System. Descriptions and stratum lines are interpretive, and actual lithologic changes may be gradual. Field descriptions may have been modified to reflect results of lab tests. 2: Descriptions on these logs apply only at the specific boring locations and at the time the borings were advanced. They are not warranted to be representative of subsurface conditions at other locations or times.
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF CPT-1
18 Project: Yountville Commons
RGH Consultants
3501 Industrial Drive, Suite A
Santa Rosa, CA 95403
www.rghgeo.com
6554 Yount Street, Yountville, California Total depth: 50.85 ft CPT: CPT-01
Location:
0 100 200
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Cone resistance
1086420
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Friction Ratio
0 100 200
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Pore pressure
Insitu
17161514131211109876543210 18
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Norm. Soil Behaviour Type
Clay
Very dense/stiff soil
Very dense/stiff soil
Very dense/stiff soil
Silty sand & sandy silt
Clay & silty clay
Very dense/stiff soil
Clay & silty clay
Clay Clay & silty clay Clay
Clay & silty clay Very dense/stiff soil
Clay & silty clay
Clay & silty clay
Clay & silty clay
Clay Clay & silty clay
Clay
Analysis method:
Fines correction method:
Points to test:
Earthquake magnitude Mw:
Peak ground acceleration:
B&I (2014)
B&I (2014)
Based on Ic value
6.97 0.71
.
G.W.T. (in-situ):
G.W.T. (earthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
25.00 ft
5.40 ft
3 2.38
Based on SBT
Use fill:
Fill height:
Fill weight:
Trans. detect. applied:
Ks applied:
No
N/A
N/A
Yes
Yes
Clay like behavior
applied:
Limit depth applied:
Limit depth:
MSF method:
.
No
N/A
Method based
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF CPT-2
19 Project: Yountville Commons
RGH Consultants
3501 Industrial Drive, Suite A
Santa Rosa, CA 95403
www.rghgeo.com
6554 Yount Street, Yountville, California Total depth: 50.69 ft CPT: CPT-02
Location:
100 200
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Cone resistance
1086420
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Friction Ratio
0 50 100
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Pore pressure
Insitu
17161514131211109876543210 18
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Norm. Soil Behaviour Type
Clay Very dense/stiff soil
Clay & silty clay
Clay
Clay & silty clay
Clay & silty clay
Clay
Clay & silty clay
Clay
Clay
Clay & silty clay
Clay Clay & silty clay Clay
Clay
Clay & silty clay
Very dense/stiff soil
Very dense/stiff soil Silty sand & sandy silt Very dense/stiff soil Clay & silty clay
Clay
Analysis method:
Fines correction method:
Points to test:
Earthquake magnitude Mw:
Peak ground acceleration:
B&I (2014)
B&I (2014)
Based on Ic value
6.97 0.71
.
G.W.T. (in-situ):
G.W.T. (earthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
12.00 ft
5.40 ft
3 2.50
Based on SBT
Use fill:
Fill height:
Fill weight:
Trans. detect. applied:
Ks applied:
No
N/A
N/A
Yes
Yes
Clay like behavior
applied:
Limit depth applied:
Limit depth:
MSF method:
.
No
N/A
Method based
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF CPT-3
20 Project: Yountville Commons
RGH Consultants
3501 Industrial Drive, Suite A
Santa Rosa, CA 95403
www.rghgeo.com
6554 Yount Street, Yountville, California Total depth: 50.52 ft CPT: CPT-03
Location:
200 400
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Cone resistance
1086420
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Friction Ratio
0 100 200
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Pore pressure
Insitu
17161514131211109876543210 18
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Norm. Soil Behaviour Type
Sand
Silty sand & sandy silt
Clay & silty clay Very dense/stiff soil
Clay & silty clay
Clay & silty clay Clay
Very dense/stiff soil
Clay & silty clay
Clay & silty clay
Clay Clay & silty clay
Clay
Clay & silty clay
Clay
Clay & silty clay
Clay Very dense/stiff soil
Clay & silty clay
Clay
Clay & silty clay
Clay & silty clay
Clay
Silty sand & sandy silt Clay & silty clay
Analysis method:
Fines correction method:
Points to test:
Earthquake magnitude Mw:
Peak ground acceleration:
B&I (2014)
B&I (2014)
Based on Ic value
6.97 0.71
.
G.W.T. (in-situ):
G.W.T. (earthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
11.50 ft
5.40 ft
3 2.41
Based on SBT
Use fill:
Fill height:
Fill weight:
Trans. detect. applied:
Ks applied:
No
N/A
N/A
Yes
Yes
Clay like behavior
applied:
Limit depth applied:
Limit depth:
MSF method:
.
No
N/A
Method based
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF CPT-4
21 Project: Yountville Commons
RGH Consultants
3501 Industrial Drive, Suite A
Santa Rosa, CA 95403
www.rghgeo.com
6554 Yount Street, Yountville, California Total depth: 50.85 ft CPT: CPT-04
Location:
50 100 150
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Cone resistance
1086420
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Friction Ratio
6040200
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Pore pressure
Insitu
17161514131211109876543210 18
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Norm. Soil Behaviour Type
Clay Very dense/stiff soil
Clay & silty clay
Silty sand & sandy silt
Clay
Very dense/stiff soil Clay & silty clay
Clay
Clay & silty clay
Clay
Clay & silty clay
Clay
Clay & silty clay
Clay
Clay
Clay
Clay & silty clay Clay Clay & silty clay Clay Clay & silty clay Clay & silty clay
Clay
Clay & silty clay
Clay
Analysis method:
Fines correction method:
Points to test:
Earthquake magnitude Mw:
Peak ground acceleration:
B&I (2014)
B&I (2014)
Based on Ic value
6.97 0.71
.
G.W.T. (in-situ):
G.W.T. (earthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
12.90 ft
5.40 ft
3 2.41
Based on SBT
Use fill:
Fill height:
Fill weight:
Trans. detect. applied:
Ks applied:
No
N/A
N/A
Yes
Yes
Clay like behavior
applied:
Limit depth applied:
Limit depth:
MSF method:
.
No
N/A
Method based
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF CPT-5
22 Project: Yountville Commons
RGH Consultants
3501 Industrial Drive, Suite A
Santa Rosa, CA 95403
www.rghgeo.com
6554 Yount Street, Yountville, California Total depth: 50.69 ft CPT: CPT-05
Location:
50 100
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Cone resistance
1086420
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Friction Ratio
0 200
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Pore pressure
Insitu
17161514131211109876543210 18
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Norm. Soil Behaviour Type
Clay Sand & silty sand
Silty sand & sandy silt
Clay & silty clay
Very dense/stiff soil
Clay & silty clay Very dense/stiff soil
Clay
Clay & silty clay
Clay
Clay & silty clay Clay Clay & silty clay
Clay & silty clay
Very dense/stiff soil
Clay & silty clay
Clay
Clay & silty clay
Clay
Clay & silty clay
Clay Clay & silty clay Silty sand & sandy silt
Analysis method:
Fines correction method:
Points to test:
Earthquake magnitude Mw:
Peak ground acceleration:
B&I (2014)
B&I (2014)
Based on Ic value
6.97 0.71
.
G.W.T. (in-situ):
G.W.T. (earthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
19.00 ft
5.40 ft
3 2.43
Based on SBT
Use fill:
Fill height:
Fill weight:
Trans. detect. applied:
Ks applied:
No
N/A
N/A
Yes
Yes
Clay like behavior
applied:
Limit depth applied:
Limit depth:
MSF method:
.
No
N/A
Method based
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF CPT-6
23 Project: Yountville Commons
RGH Consultants
3501 Industrial Drive, Suite A
Santa Rosa, CA 95403
www.rghgeo.com
6554 Yount Street, Yountville, California Total depth: 50.69 ft CPT: CPT-06
Location:
50 100
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Cone resistance
1086420
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Friction Ratio
0 200
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Pore pressure
Insitu
17161514131211109876543210 18
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Norm. Soil Behaviour Type
Clay Clay & silty clay Silty sand & sandy silt Clay
Very dense/stiff soil Clay & silty clay
Very dense/stiff soil
Very dense/stiff soil
Very dense/stiff soil
Clay & silty clay
Clay
Clay & silty clay Clay Clay & silty clay
Clay & silty clay Clay
Clay
Clay & silty clay
Clay
Clay & silty clay
Clay
Clay
Analysis method:
Fines correction method:
Points to test:
Earthquake magnitude Mw:
Peak ground acceleration:
B&I (2014)
B&I (2014)
Based on Ic value
6.97 0.71
.
G.W.T. (in-situ):
G.W.T. (earthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
18.00 ft
5.40 ft
3 2.37
Based on SBT
Use fill:
Fill height:
Fill weight:
Trans. detect. applied:
Ks applied:
No
N/A
N/A
Yes
Yes
Clay like behavior
applied:
Limit depth applied:
Limit depth:
MSF method:
.
No
N/A
Method based
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF CPT-7
24 Project: Yountville Commons
RGH Consultants
3501 Industrial Drive, Suite A
Santa Rosa, CA 95403
www.rghgeo.com
6554 Yount Street, Yountville, California Total depth: 50.69 ft CPT: CPT-07
Location:
100
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Cone resistance
1086420
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Friction Ratio
0 200
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Pore pressure
Insitu
17161514131211109876543210 18
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Norm. Soil Behaviour Type
Clay
Silty sand & sandy silt Clay & silty clay
Very dense/stiff soil
Very dense/stiff soil
Clay & silty clay Very dense/stiff soil
Clay & silty clay
Clay & silty clay Clay Clay & silty clay Very dense/stiff soil Clay & silty clay Clay
Clay & silty clay
Clay
Clay & silty clay Clay
Clay & silty clay
Clay & silty clay Clay Silty sand & sandy silt Very dense/stiff soil Clay & silty clay
Clay
Analysis method:
Fines correction method:
Points to test:
Earthquake magnitude Mw:
Peak ground acceleration:
B&I (2014)
B&I (2014)
Based on Ic value
6.97 0.71
.
G.W.T. (in-situ):
G.W.T. (earthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
5.40 ft
5.40 ft
3 2.35
Based on SBT
Use fill:
Fill height:
Fill weight:
Trans. detect. applied:
Ks applied:
No
N/A
N/A
Yes
Yes
Clay like behavior
applied:
Limit depth applied:
Limit depth:
MSF method:
.
No
N/A
Method based
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
LOG OF CPT-8
25 Project: Yountville Commons
RGH Consultants
3501 Industrial Drive, Suite A
Santa Rosa, CA 95403
www.rghgeo.com
6554 Yount Street, Yountville, California Total depth: 50.69 ft CPT: CPT-08
Location:
50 100
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Cone resistance
1086420
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Friction Ratio
0 100
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Pore pressure
Insitu
17161514131211109876543210 18
50 48
46 44
42 40
38 36
34 32
30 28
26 24
22 20
18 16
14 12
10 8
6 4
2 0
Norm. Soil Behaviour Type
Clay
Clay
Clay & silty clay Very dense/stiff soil
Clay
Clay & silty clay
Clay Clay & silty clay Clay Clay & silty clay
Clay & silty clay Clay
Clay & silty clay
Clay
Clay & silty clay
Clay
Clay & silty clay
Analysis method:
Fines correction method:
Points to test:
Earthquake magnitude Mw:
Peak ground acceleration:
B&I (2014)
B&I (2014)
Based on Ic value
6.97 0.71
.
G.W.T. (in-situ):
G.W.T. (earthq.):
Average results interval:
Ic cut-off value:
Unit weight calculation:
8.00 ft
5.40 ft
3 2.25
Based on SBT
Use fill:
Fill height:
Fill weight:
Trans. detect. applied:
Ks applied:
No
N/A
N/A
Yes
Yes
Clay like behavior
applied:
Limit depth applied:
Limit depth:
MSF method:
.
No
N/A
Method based
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
CLASSIFICATION TEST DATA
26 Tested By: SCW Checked By: SEF
LIQUID AND PLASTIC LIMITS TEST REPORT
0 10
20 30
40 50
60 LIQUID LIMIT
0 10 20 30 40 50 60 70 80 90 100 110
CL-ML ML or OL MH or OH
Dashed line indicates the approximate
upper limit boundary for natural soils
4 7 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS
Project No. Remarks:
Project:
Figure
Source of Sample: B-1 Depth: 1.5' & 2.0'
Source of Sample: B-1 Depth: 6.0'
Brown Sandy Clay W/ Gravel (CL) 31.4 18.2 13.2 50.5 CL
Brown Clayey Sand (SC) 61.6 29.1 32.5 39.3 SC
6860.022.PW.2
Expansion Index= 15 (Very Low) Yountville Commons
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
CLASSIFICATION TEST DATA
27 Tested By: SCW Checked By: SAA
LIQUID AND PLASTIC LIMITS TEST REPORT
0 10
20 30
40 50
60 LIQUID LIMIT
0 10 20 30 40 50 60 70 80 90 100 110
CL-ML ML or OL MH or OH
Dashed line indicates the approximate
upper limit boundary for natural soils
4 7 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS
Project No. Remarks:
Project:
Figure
Source of Sample: B-2 Depth: 5.5'
Source of Sample: B-3 Depth: 1.5' & 2.0'
Source of Sample: B-6 Depth: 0.5'-3.0'
Brown Silty Sand w/ Gravel (SM) 64.2 32.3 31.9 31.4 SM
Brown Clayey Sand (SC) 36.1 20.8 15.3 49.9 SC
Brown Sandy Clay (CL) 35.1 20.1 15.0 CL
6860.022.PW.2
Expansion Index = 44 (Low)
Expansion Index = 32 (Low)
Yountville Commons
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
CLASSIFICATION TEST DATA
28 Tested By: SCW Checked By: SAA
LIQUID AND PLASTIC LIMITS TEST REPORT
0 10
20 30
40 50
60 LIQUID LIMIT
0 10 20 30 40 50 60 70 80 90 100 110
CL-ML ML or OL MH or OH
Dashed line indicates the approximate
upper limit boundary for natural soils
4 7 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS
Project No. Remarks:
Project:
Figure
Source of Sample: B-8 Depth: 2.0'-3.5'
Source of Sample: B-11 Depth: 0.5'-5.0'
Source of Sample: B-12 Depth: 0.5'-4.5'
Dark Brown Sandy Clay (CL) 49.5 25.6 23.9 CL
Dark Brown Sandy Clay (CL) 37.4 24.1 13.3 CL
Brown Sandy Clay (CL) 32.9 21.7 11.2 CL
6860.022.PW.2
Expansion Index = 45 (Low)
Expansion Index = 25 (Low)
Expansion Index = 26 (Low)
Yountville Commons
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
TRIAXIAL TEST DATA
29 Tested By: SCW Checked By: SAA
Project: Yountville Commons
Source of Sample: B-3 Depth: 6.0'
Proj. No.: 6860.022.PW.2 Date Sampled: 7/24/25
Type of Test:
Unconsolidated Undrained
Sample Type: California Modified Tube
Description: Brown Clayey Sand (SC)
Assumed Specific Gravity= 2.70
Remarks:
Figure
Sample No.
Water Content, %
Dry Density, pcf
Saturation, %
Void Ratio
Diameter, in.
Height, in.
Water Content, %
Dry Density, pcf
Saturation, %
Void Ratio
Diameter, in.
Height, in.
Strain, %
Strain, %
Strain rate, in./min.
Back Pressure, psi
Cell Pressure, psi
Fail. Stress, psf
Ult. Stress, psf 1 Failure, psf 3 Failure, psf
1 28.6
93.8 96.8
0.7977
2.40 6.00
28.6 93.8
96.8 0.7977
2.40 6.00
0.060
5.3 0.00
5.00 4518
4518
5.3 720
5238
0 1000
2000
3000
4000
5000
6000
Axial Strain, %
0 5 10 15 20
1 0
900
1800
2700
Normal Stress, psf
0 900 1800 2700 3600 4500 5400
C, psf
, deg
Tan( )
Results
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
TRIAXIAL TEST DATA
30 Tested By: SCW Checked By: SAA
Project: Yountville Commons
Source of Sample: B-4 Depth: 3.5'
Proj. No.: 6860.022.PW.2 Date Sampled: 7/25/25
Type of Test:
Unconsolidated Undrained
Sample Type: California Modified Tube
Description: Brown Clayey Sand (SC)
Assumed Specific Gravity= 2.70
Remarks: Expansion Index = 60 (Medium)
Figure
Sample No.
Water Content, %
Dry Density, pcf
Saturation, %
Void Ratio
Diameter, in.
Height, in.
Water Content, %
Dry Density, pcf
Saturation, %
Void Ratio
Diameter, in.
Height, in.
Strain, %
Strain, %
Strain rate, in./min.
Back Pressure, psi
Cell Pressure, psi
Fail. Stress, psf
Ult. Stress, psf 1 Failure, psf 3 Failure, psf
1 14.6
116.7
88.8 0.4437
2.40 6.00
14.6 116.7
88.8 0.4437
2.40 6.00
0.060
2.7 0.00
5.00 12625
12625
2.7 720
13345
0 2500
5000
7500
10000
12500
15000
Axial Strain, %
0 1 2 3 4
1 0
3000
6000
9000
Normal Stress, psf
0 3000 6000 9000 12000 15000 18000
C, psf
, deg
Tan( )
Results
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
TRIAXIAL TEST DATA
31 Tested By: SCW Checked By: SAA
Project: Yountville Commons
Source of Sample: B-4 Depth: 9.0'
Proj. No.: 6860.022.PW.2 Date Sampled: 7/25/25
Type of Test:
Unconsolidated Undrained
Sample Type: California Modified Tube
Description: Brown Clay (CH)
Assumed Specific Gravity= 2.70
Remarks:
Figure
Sample No.
Water Content, %
Dry Density, pcf
Saturation, %
Void Ratio
Diameter, in.
Height, in.
Water Content, %
Dry Density, pcf
Saturation, %
Void Ratio
Diameter, in.
Height, in.
Strain, %
Strain, %
Strain rate, in./min.
Back Pressure, psi
Cell Pressure, psi
Fail. Stress, psf
Ult. Stress, psf 1 Failure, psf 3 Failure, psf
1 31.6
90.5 98.7
0.8633
2.40 5.75
31.6 90.5
98.7 0.8633
2.40 5.75
0.060
9.7 0.00
5.00 7521
7521
9.7 720
8241
0 1500
3000
4500
6000
7500
9000
Axial Strain, %
0 5 10 15 20
1 0
1400
2800
4200
Normal Stress, psf
0 1400 2800 4200 5600 7000 8400
C, psf
, deg
Tan( )
Results
PLATE
Job No: 6860.022.PW.2
Yountville Commons
6554 Yount Street
Yountville, California
Date: SEPT 2025
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Page B-1
APPENDIX B - REFERENCES
American Society of Civil Engineers, 2022, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, ASCE Standard ASCE/SEI 7-22.
Bezore, S.P., Clahan, K.B., Sowers, J.M., and Witter, R.C., 2005, Geologic map of the Yountville 7.5-minute quadrangle, Napa County, California: A digital database.: California Geological Survey, Preliminary Geologic Maps PGM-05-02, scale 1:24,000
Bryant, W.A., and Hart, E.W., Interim Revision 2007, Fault-Rupture Zones in California; California Geological Survey, Special Publication 42, p. 21 with Appendices A through F.
Building Seismic Safety Council (BSSC), 2014, Building Seismic Safety Council 2014 Event Set, accessed between October 2019 and February 2020. Available online at https://earthquake.usgs.gov/scenarios/catalog/bssc2014/.
California Building Code, 2025, California Building Standard Commission.
California Department of Transportation, 2020, Highway Design Manual, Chapter 630 - Flexible Pavement.
Federal Emergency Management Agency, September 26, 2008, Flood Insurance Rate Map, Town of Yountville, California, Community Panel Number 06055C0413E Geologismiki, 2006, CLiq, a computer program for CPT data analysis and liquefaction calculations, Serres, Greece.
Idriss, I.M. and Boulanger, R.W., 2004, Semi-Empirical Procedures for Evaluating Liquefaction Potential During Earthquakes, Proceedings of the 11th ICSDEE and 3rd ICEGE, pp. 32-56.
Idriss, I.M. and Boulanger, R.W., 2008, Soil Liquefaction During Earthquakes.
Idriss, I.M. and Boulanger, R.W., 2014, CPT and SPT Based Liquefaction Triggering Procedures.
Ishihara, K., and Yoshimine, M., 1992, Evaluation of settlements in sand deposits following liquefaction during earthquakes, Soils and Foundations 32(1), 173-88.
Lew, M, Sitar, N, Al Atik, L, Pourzanjani, M, and Hudson, M.B., Seismic Earth Pressures on Deep Building Basements, SEAOC 2010 Convention Proceedings.
Natural Resources Conservation Service, United States Department of Agriculture, accessed August 2025.
Web Soil Survey, available online at http://websoilsurvey.nrcs.usda.gov/.
Robertson, P.K., 1990, Soil Classification using the Cone Penetration Test, Department of Civil Engineering, University of Alberta, Edmonton, Alberta, Canada, Canadian Geotechnical Journal, J. 27, 151-158.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Page B-2
Robertson, P.K., 2015, Comparing CPT and Vs Liquefaction Triggering Methods, Journal of Geotechncial and Geoenvironmental Engineering, American Society of Civil Engineers, v. 141, No. 9.
Seed, H.B. and Idriss, I.M., 1982, Ground Motion and Soil Liquefaction During Earthquakes: Earthquake Engineering Research Institute, Berkeley, California.
Seed, H.B., Tokimatsu, K., Harder, L.F., and Chung, R.M., 1985, Influence of SPT Procedures in Soil Liquefaction Resistance Evaluations: Journal of Geotechnical Engineering Division, American Society of Civil Engineers, v. III, no. 12, December, p. 1425-1445.
Seed, R.B., Cetin, K.O., Moss, R.E.S., Kammerer, A.M., Wu, J., Pestana, J.M., Riemer, M.F., Sancio, R.B., Bray, J.D., Kayen, R.E., and Faris, A., 2003, Recent Advances in Soil Liquefaction: A Unified and Consistent Framework: Earthquake Engineering Research Center Report No. EERC 2003-06, College of Engineering, University of California, Berkeley.
Youd, T.L., and Idriss, I.M., and 19 others, 2001, Liquefaction Resistance of Soils: summary report from the 1996 NCEER and 1998 NCEER/NSF workshops on evaluation of liquefaction resistance of soils:
ASCE Geotechnical and Geoenvironmental Journal, v. 127, no. 10, p. 817-833.
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
Page C-1
APPENDIX C – SHEAR WAVE VELOCITY REPORTS
YC_SN_20ft Shear-Wave Velocity Report
Yountville Commons Terēan VsSurf ReMi™ 2.1 Software
Array Location
Datum: WGS84
Site Name: YC_SN_20ft
Center: 38.404225, -122.361921
Geophone 1: 38.403906, -122.361844
Geophone12: 38.404509, -122.362008
Results
Vs100: 1,155 ft/s
Site Class: CD
ASCE: ASCE 7-22
Depth: 110 ft
Survey Parameters
Geophone Count: 12
Geophone Spacing: 20 ft
Array Length: 220 ft
Survey Date: 07/23/2025
Performed By: RGH Consultants
Analysis By: PLB
Analysis Date: Mon Jul 28 08:36:06 PDT 2025
Narrative
SHEAR WAVE VELOCITIES AND SEISMIC SITE CLASS
RGH Consultants’s geophysical site evaluation included subsurface seismic imaging and earthquake ground shaking potential evaluation using Terēan’s VsSurf ReMi™ seismic data processing software.
Seismic surveys were performed to determine depth to bedrock and the seismic site class per ASCE 7-22 using the weighted-average soil shear wave velocity for the upper 100 feet (Vs100). The surveys were performed by recording active and/or ambient (passive) seismic sources. The seismic recording array for these surveys consisted of 12, 4.5 Hz geophones at 20 ft spacing, for a total survey length of 220 feet.
Noise generated by walking along the line and 12-pound hammer blows during data acquisition while ambient noise was generated from traffic along the nearby roads. The seismic data were acquired using a ReMiNode 2-12™ seismograph, while data was processed using Terēan's ReMi™ software (terean.com/products). Survey results indicate a weighted-average soil shear wave velocity of the upper 100 feet (Vs100) of 1,155 ft/s. This results in a designation of a Seismic Site Class CD according to Table ASCE 7-22.
YC_SN_20ft Shear-Wave Velocity Report
Yountville Commons Terēan VsSurf ReMi™ 2.1 Software
Depth Vs
(ft) (ft/s)
0.0 661
18.4 661
18.4 918
27.2 918
27.2 1,384
70.7 1,384
70.7 1,698
110.0 1,698
YC_SN_20ft Shear-Wave Velocity Report
Yountville Commons Terēan VsSurf ReMi™ 2.1 Software
Frequency Slowness
(Hz) (s/m)
33.691 0.00524 Seismic File: 0001.sgy
26.855 0.00524 Pre-Processing: preprocess
23.437 0.00524 Surveyed Geophones: No
20.996 0.00524 Max Frequency, Hz: 50
19.042 0.00524 Min Velocity, m/s: 152
16.113 0.00511
15.136 0.00485
14.648 0.00472
14.160 0.00446
13.183 0.00406
11.718 0.00380
10.742 0.00354
8.789 0.00328
8.301 0.00314
7.324 0.00301
6.836 0.00288
5.859 0.00275
4.883 0.00262
3.906 0.00249
3.418 0.00236
YC2_SN_20ft Shear-Wave Velocity Report
Yountville Commons Terēan VsSurf ReMi™ 2.1 Software
Array Location
Datum: WGS84
Site Name: YC2_SN_20ft
Center: 38.404677, -122.360352
Geophone 1: 38.404406, -122.360194
Geophone12: 38.404945, -122.360514
Results
Vs100: 813 ft/s
Site Class: D
ASCE: ASCE 7-22
Depth: 110 ft
Survey Parameters
Geophone Count: 12
Geophone Spacing: 20 ft
Array Length: 220 ft
Survey Date: 07/23/2025
Performed By: RGH Consultants
Analysis By: PLB
Analysis Date: Mon Jul 28 09:16:44 PDT 2025
Narrative
SHEAR WAVE VELOCITIES AND SEISMIC SITE CLASS
RGH Consultants’s geophysical site evaluation included subsurface seismic imaging and earthquake ground shaking potential evaluation using Terēan’s VsSurf ReMi™ seismic data processing software.
Seismic surveys were performed to determine depth to bedrock and the seismic site class per ASCE 7-22 using the weighted-average soil shear wave velocity for the upper 100 feet (Vs100). The surveys were performed by recording active and/or ambient (passive) seismic sources. The seismic recording array for these surveys consisted of 12, 4.5 Hz geophones at 20 ft spacing, for a total survey length of 220 feet.
Noise generated by walking along the line and 12-pound hammer blows during data acquisition while ambient noise was generated from traffic along the nearby roads. The seismic data were acquired using a ReMiNode 2-12™ seismograph, while data was processed using Terēan's ReMi™ software (terean.com/products). Survey results indicate a weighted-average soil shear wave velocity of the upper 100 feet (Vs100) of 813 ft/s. This results in a designation of a Seismic Site Class D according to Table ASCE 7-22.
YC2_SN_20ft Shear-Wave Velocity Report
Yountville Commons Terēan VsSurf ReMi™ 2.1 Software
Depth Vs
(ft) (ft/s)
0.0 450
9.5 450
9.5 723
50.0 723
50.0 834
64.0 834
64.0 1,268
110.0 1,268
YC2_SN_20ft Shear-Wave Velocity Report
Yountville Commons Terēan VsSurf ReMi™ 2.1 Software
Frequency Slowness
(Hz) (s/m)
41.015 0.00787 Seismic File: 0001.sgy
33.691 0.00787 Pre-Processing: preprocess
31.738 0.00768 Surveyed Geophones: No
27.832 0.00749 Max Frequency, Hz: 50
26.367 0.00749 Min Velocity, m/s: 107
24.902 0.00731
23.437 0.00712
21.972 0.00693
20.019 0.00674
19.042 0.00656
17.578 0.00637
16.113 0.00599
14.160 0.00581
10.742 0.00543
9.766 0.00543
8.789 0.00543
8.301 0.00543
7.812 0.00543
6.836 0.00506
6.348 0.00487
5.859 0.00468
4.883 0.00431
3.906 0.00374
RGH
CONSULTANTS
Geotechnical Study Report Yountville Commons
September 16, 2025 Project Number: 6860.022.PW.2
EGC:JJP:plb:brw
Copyright 2025 by RGH Consultants
https://rghgeo.sharepoint.com/sites/shared/shared documents/project files/6751-7000/6860/6860.022.pw.2 yountville commons/.01 - gs/6860.022.pw.2 gs report.docx
Page D-1
APPENDIX D - DISTRIBUTION
Town of Yountville (e)
Attn: John Ferons
6550 Yount Street
Yountville, CA 94599
[email protected]
Pound Management (e)
Attn: Sean Grinnell
[email protected]
Important Information About Your
Geotechnical Engineering Report
Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes The following information is provided to help you manage your risks.
Geotechnical Services Are Performed for
Specifi c Purposes, Persons, and Projects
Geotechnical engineers structure their services to meet the specifi c needs of their clients. A geotechnical engineering study conducted for a civil engineer may not fulfi ll the needs of 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 engineering report without fi rst conferring with the 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-Specifi c Factors
Geotechnical engineers consider a number of unique, project-specifi c factors when establishing the scope of a study. Typical factors include: the client’s goals, objectives, and risk management preferences; the general nature of the structure involved, its size, and confi guration; 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 the geotechnical engineer who conducted the study specifi cally indicates otherwise, do not rely on a geotechnical engineering report that was:
• not prepared for you,
• not prepared for your project,
• not prepared for the specifi c site explored, or
• completed before important project changes were made.
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 from a parking garage to an offi ce building, or from alight industrial plant to a refrigerated warehouse,
• elevation, confi guration, location, orientation, or weight of the proposed structure,
• composition of the design team, or
• project ownership.
As a general rule, always inform your 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
A geotechnical engineering report is based on conditions that existed at the time the study was performed. Do not rely on a geotechnical engineering 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 fl oods, earthquakes, or groundwater fl uctuations. Always contact the geotechnical engineer before applying the report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems.
Most Geotechnical Findings Are Professional
Opinions
Site exploration identifi es subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engineers review fi eld 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 signifi cantly from those indicated in your report. Retaining the geotechnical engineer who developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipated conditions.
A Report’s Recommendations Are Not Final
Do not overrely on the construction recommendations included in your report. Those recommendations are not fi nal, because geotechnical engineers develop them principally from judgment and opinion. Geotechnical engineers can fi nalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engineer who developed your report cannot assume responsibility or liability for the report’s recommendations if that engineer does not perform construction observation.
A Geotechnical Engineering Report Is Subject to
Misinterpretation
Other design team members’ misinterpretation of geotechnical engineering reports has resulted in costly problems. Lower that risk by having your geotechnical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review pertinent elements of the design team’s plans and specifi cations. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing construction observation.
Do Not Redraw the Engineer’s Logs
Geotechnical engineers prepare fi nal boring and testing logs based upon their interpretation of fi eld logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in architectural or other design drawings.
Only photographic or electronic reproduction is acceptable, but recognize 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, advise 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 the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct additional study to obtain the specifi c types of information they need or prefer.
A prebid conference can also be valuable. Be sure contractors have suffi cient time to perform additional study. Only then might you be in a position to give contractors the best information available to you, while requiring them to at least share some of the fi nancial responsibilities stemming from unanticipated conditions.
Read Responsibility Provisions Closely
Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than other engineering disciplines.
This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled “limitations” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly.
Geoenvironmental Concerns Are Not Covered
The equipment, techniques, and personnel used to perform a geoenvironmental study differ signifi cantly from those used to perform a geotechnical study. For that reason, a geotechnical engineering report does not usually relate any geoenvironmental fi ndings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own geoenvironmental information, ask your geotechnical consultant for risk management guidance.
Do not rely on an environmental report prepared for someone else.
Obtain Professional Assistance To Deal with Mold
Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent signifi cant amounts of mold from growing on indoor surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional mold prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, a number of mold prevention strategies focus on keeping building surfaces dry. While groundwater, water infi ltration, and similar issues may have been addressed as part of the geotechnical engineering study whose fi ndings are conveyed in-this report, the geotechnical engineer in charge of this project is not a mold prevention consultant; none of the services performed in connection with the geotechnical engineer’s study were designed or conducted for the purpose of mold prevention. Proper implementation of the recommendations conveyed in this report will not of itself be suffi cient to prevent mold from growing in or on the structure involved.
Rely on Your ASFE-Member Geotechnical
Engineer For Additional Assistance
Membership in ASFE/The Best People on Earth exposes geotechnical engineers to a wide array of risk management techniques that can be of genuine benefi t for everyone involved with a construction project. Confer with your ASFE-member geotechnical engineer for more information. 8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone:’ 301/565-2733 Facsimile: 301/589-2017
e-mail: [email protected] www.asfe.org
Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with ASFE’s specifi c written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of ASFE, and only for purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any other fi rm, individual, or other entity that so uses this document without being anASFE member could be committing negligent or intentional (fraudulent) misrepresentation.
IIGER06045.0M
The Best People on Earth