REPORT UPDATED GEOTECHNICAL STUDY PROPOSED … · 2020-02-20 · Goldenwest Credit Union Job No....

REPORT UPDATED GEOTECHNICAL STUDY

PROPOSED GOLDENWEST CREDIT UNION APPROXIMATELY 220 EAST 1400 NORTH STREET

LOGAN, UTAH

Submitted To:

Goldenwest Credit Union 5025 South Adams Avenue South Ogden, Utah 84403

Submitted By:

GSH Geotechnical, Inc. 473 West 4800 South

Salt Lake City, Utah 84123

January 21, 2019

Job No. 0645-001A-20

Gordon Spilker Huber Geotechnical Consultants, Inc. 4426 South Century Drive, Suite 100 Salt Lake City, Utah 84123 Tel: (801) 685-9190 Fax: (801) 685-2990 www.gshgeotech.com

January 21, 2020 Job No. 0645-01A-20 Mr. Butch Campbell Goldenwest Credit Union 5025 South Adams Avenue South Ogden, Utah 84403 Mr. Campbell Re: Report Updated Geotechnical Study

Proposed Goldenwest Credit Union Approximately 220 East 1400 North Street Logan, Utah

1. INTRODUCTION 1.1 GENERAL This report presents the results of our updated geotechnical study performed at the site of the proposed Goldenwest Credit Union, which is located at approximately 220 East 1400 North Street in Logan, Utah. The general location of the site with respect to major topographic features and existing facilities, as of 1998, is presented on Figure 1, Vicinity Map. A more detailed layout of the site showing the locations of the proposed building and pavement areas, along with the existing roadways, is presented on Figure 2, Site Plan. The approximate locations of the borings drilled in conjunction with this study are also presented on Figure 2. GSH previously completed a geotechnical study for the site dated November 19, 20071. 1.2 OBJECTIVES AND SCOPE The objectives and scope of our study were planned in discussions among Mr. Eric Malmberg of Anderson Wahlen & Associates, Mr. Butch Campbell of Goldenwest Credit Union, and Mr. Mike Huber of GSH Geotechnical Consultants, Inc. (GSH).

1 “Report, Proposed Golden West Credit Union, Geotechnical Study, Approximately 200 East Street and 1400

North Street, Logan, Utah.” GSH Job No. 0645-001-07.

Goldenwest Credit Union Job No. 0645-01A-20 Updated Geotechnical Study January 21, 2020

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In general, the objectives of this study were to:

1. Define and evaluate the subsurface soil and groundwater conditions at the site. 2. Provide appropriate foundation, earthwork, pavement, and geoseismic

recommendations to be utilized in the design and construction of the proposed facilities.

In accomplishing these objectives, our scope has included the following:

1. A field program consisting of the drilling, logging, and sampling of 3 borings.

2. Update visit to the site.

2. A laboratory testing program.

3. An office program consisting of the correlation of available data, engineering analyses, and the preparation of this summary report.

1.3 AUTHORIZATION Authorization was provided with email correspondence between Mr. Malmberg and Mr. Huber. 1.4 PROFESSIONAL STATEMENTS Supporting data upon which our recommendations are based are presented in subsequent sections of this report. Recommendations presented herein are governed by the physical properties of the soils encountered in the exploration borings, projected groundwater conditions, and the layout and design data discussed in Section 2., Proposed Construction, of this report. If subsurface conditions other than those described in this report are encountered, and/or if design and layout changes are implemented, GSH must be informed so that our recommendations can be reviewed and amended, if necessary. Our professional services have been performed, our findings developed, and our recommendations prepared in accordance with generally accepted engineering principles and practices in this area at this time. 2. PROPOSED CONSTRUCTION The proposed structure will be one to one-extended level in height and established slab on grade. The building will be CMU and light steel-frame construction. A “drive-thru” canopy will extend east of the main structure.


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Anticipated maximum real column and wall loads will be on the order of 50 to 60 kips and 3 to 4 kips per lineal foot, respectively. Real loads are defined as the total of all dead plus frequently applied (reduced) live loads. Average uniform floor slab loading is anticipated to be light, less than 200 pounds per square foot. Associated with the structure will be new pavements. Traffic over the pavements will consist of a light to moderate volume of automobiles and light trucks and a light volume of medium-weight trucks and occasional heavyweight trucks. As part of the site development, some cutting and filling will be required to obtain grade. It is projected that the maximum cuts and fills will be on the order of 3 to 4 feet. 3. SITE INVESTIGATIONS 3.1 FIELD PROGRAM In order to define and evaluate the subsurface soil and groundwater conditions at the site, 3 borings were drilled to depths ranging from 5 to 16 feet with a truck-mounted drill rig equipped with hollow-stem augers. Approximate locations of the borings are presented on Figure 2. Additionally, a visit to the site was completed by GSH personnel in order to observe current conditions and to provide additional recommendations (if necessary). The field portion of our study was under the direct control and continual supervision of an experienced member of our geotechnical staff. During the course of the drilling operations, a continuous log of the subsurface conditions encountered was maintained. In addition, samples of the typical soils encountered were obtained for subsequent laboratory testing and examination. The soils were classified in the field based upon visual and textural examination. These classifications have been supplemented by subsequent inspection and testing in our laboratory. Detailed graphical representation of the subsurface conditions encountered is presented on Figures 3A through 3C, Log of Borings. Soils were classified in accordance with the nomenclature described on Figure 4, Key to Boring Log (USCS). A 3.25-inch outside diameter, 2.42-inch inside diameter drive sampler (Dames & Moore) was utilized in the subsurface sampling at the site. The blow-counts recorded on the boring logs were those required to drive the sampler 12 inches with a 140-pound hammer dropping 30 inches. Following completion of drilling operations, one and one-quarter-inch diameter slotted PVC pipe was installed in Borings B-1 and B-2 in order to provide a means of monitoring the groundwater fluctuations.


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3.2 LABORATORY TESTING 3.2.1 General In order to provide data necessary for our engineering analyses, a laboratory testing program was performed. The program included moisture, density, consolidation, partial gradation, and chemical tests. The following paragraphs describe the tests and summarize the test data. 3.2.2 Moisture and Density Tests To aid in classifying the soils, moisture and density tests were performed on selected samples. The results of these tests are presented on the boring logs, Figures 3A through 3C. 3.2.3 Consolidation Tests To provide data necessary for our settlement analyses, a consolidation test was performed on each of 3 representative samples of the fine-grained cohesive soils encountered in the exploration borings. The results of these tests indicate that the clays are moderately over-consolidated and will exhibit moderate compressibility characteristics when loaded below the consolidation pressure. Detailed results of the tests are maintained within our files and can be transmitted to you, upon your request. 3.2.4 Partial Gradation Test To aid in classifying the granular soils, a partial gradation test was performed. Results of the test are tabulated below:

Boring No.

Depth (feet)

Percent Passing No. 200 Sieve

Soil Classification

B-1 15.0 84.0 ML 3.2.5 Chemical Tests To determine if the site soils will react detrimentally with concrete, chemical tests were performed on a representative sample of the near-surface soils. The results of the chemical tests are tabulated below:

Boring No.

Depth (feet)

pH

Total Water Soluble Sulfate (mg/L)

B-2 3.0 8.09 *

* Below detectible limits.


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4. SITE CONDITIONS 4.1 SURFACE The site is located at approximately 220 East 1400 North Street in Logan, Utah. As part of this updated report, GSH personnel visited the site on January 8, 2020. The purpose of the visit was to observe current surficial and provide additional recommendations (if required). The site is currently bounded to the north by 1400 North Street with a Lowe’s Home Improvement store and detention pond beyond, to the east by a Big-O Tire And Service Center with a car wash facility beyond, to the south by a church meetinghouse structure and associated pavements, and the west by 200 East Street followed by a GNC retail store, multi-tenant retail facility, and associated pavements. The site is relatively level with a downward slope to the south and west. Overall elevation change is on the order of 5 to 7 feet. The site is 3 to 4 feet lower than the Big-O site to the east and 1400 North Street to the north. An irrigation ditch was observed along the southern edge of the site. The site is open and undeveloped with some scattered grasses and weeds with some bushes and trees along the borders of the property. 4.2 SUBSURFACE AND GROUNDWATER The soil conditions encountered in the borings, to the depths penetrated, were relatively similar. Silty clays were encountered from the surface to depths of 5 to 13 feet. The clays are brown, slightly moist to saturated, stiff to very stiff, and will exhibit moderate strength and compressibility characteristics. In Boring B-1, the clays are underlain by clayey silts that extend to a depth of 16 feet. The silts are brown, saturated, medium dense, and will exhibit moderate strength and compressibility characteristics. The lines designating the interface between soil types on the boring logs generally represent approximate boundaries. In-situ, the transition between soil types may be gradual. Immediately following drilling operations, groundwater was measured at a depth of 9 feet below existing grade. Three days after drilling, groundwater was measured at depths of 5.3 to 5.4 feet below existing grade. Seasonal and longer-term groundwater fluctuations on the order of 1 to 2 feet are projected, with the highest seasonal levels generally occurring during the late spring and early summer months.


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5. DISCUSSIONS AND RECOMMENDATIONS 5.1 SUMMARY OF FINDINGS The most significant geotechnical aspect of the site is the moderately high groundwater table. Groundwater was encountered at depths ranging from 5.3 to 5.4 feet; recommendations for groundwater are presented in Section 5.2 Design Water Table, of this report. The results of this study indicate that the proposed structure can be supported upon conventional spread and continuous wall foundations. The footings may be established upon suitable undisturbed natural soils and/or structural fills extending to suitable natural soils. Detailed discussions pertaining to the design water table, earthwork, foundation, pavements, and the geoseismic setting of the site are discussed in the following sections. 5.2 DESIGN WATER TABLE The water table was measured at a depth of 5.3 to 5.4 feet below existing grade. Considering seasonal and long-term groundwater fluctuations, we recommend that the design groundwater table of 3.3 to 3.4 feet below existing grade be utilized in the design. We recommend that all habitable floor slabs be established a minimum of 4 feet above the design water table or 1.5 feet if foundation and floor slab subdrains are implemented. Site grading fill may be required to raise slabs the required distance from the groundwater. 5.2.1 Subdrain A subdrain system, if utilized, should consist of a perimeter foundation/chimney subdrain and an under-slab subdrain. The perimeter subdrain would consist of a 4-inch diameter slotted or perforated PVC or other durable material pipe installed with an invert at least 18 inches below the top of the lowest adjacent slab. The drain pipe should slope at least 0.25 percent to a suitable point of gravity discharge, such as an inside or outside sump. The 4-inch diameter slotted PVC pipe should be encased in a one-half to three-quarter-inch clean gap-graded gravel extending 2 inches below laterally and continuously up at least 12 inches above the top of the lowest adjacent slab. The gravels must be separated from the adjacent soils with a geotextile fabric, such as Mirafi 140N or equivalent. Extending up from the top of the foundation subdrain to within 1 foot of final grade should be a synthetic drain board or a zone of “free-draining” permeable fill, also separated from all adjacent soils with a geotextile fabric. Prior to the placement of the perimeter foundation subdrain, the outside subgrade walls should be appropriately waterproofed. In addition to the perimeter foundation/chimney subdrain, an under-slab drain is recommended. This should consist of a minimum of 8 inches of “free-draining” one-half to three-quarter-inch minus clean gap-graded gravel placed over properly prepared suitable natural subgrade soils and/or structural fill extending to suitable natural soil. The “free-draining” gravel shall be hydraulically connected to the perimeter drain. In addition, we recommend 4-inch diameter slotted PVC pipes


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be installed laterally and spaced approximately 50 feet apart beneath the below-grade level slab of the structure with an invert elevation of at least 12 inches below the top of the lowest adjacent slab. This subdrain would be similarly encased in the one-half- to three-quarter-inch clean gap-graded gravel, separated from the natural soils with a geotextile fabric, extending up to the 6-inch layer of gravel underneath the at-grade slab. This subdrain line would discharge to the perimeter subdrain. GSH also recommends that a minimum of 10.0 inches of “free-draining” gravel material be placed below the floor slab and that this gravel be hydraulically tied to the perimeter foundation drain. This may be accomplished by placing footings on a minimum of 6.0 inches of similar “free-draining” gravel material. Lateral drains must also be placed approximately every 50 feet and tied to the subdrain system. Water collected by the subdrain system would be gravity discharged or pumped to a suitable discharge point such as area subdrains, storm drains, or other suitable down-gradient location (see attached Figure 5, Typical Foundation/Chimney Subdrain Detail 18”). A back-up power and back-up pump would need to be incorporated against failure if a suitable gravity discharge system is unavailable. 5.3 EARTHWORK 5.3.1 Site Preparation Preparation of the site must consist of the removal of all non-engineered fills, loose surficial soils, surface vegetation, topsoil, and other deleterious materials from beneath an area extending at least 3 feet beyond the perimeter of the proposed building, pavement, and exterior flatwork areas. Subsequent to the above-defined criteria and prior to the placement of structural site grading fill, floor slab, and pavements, the subgrade must be proof rolled by running moderate-weight rubber tire-mounted equipment over the subgrade at least twice. If unsuitable soils are encountered, they must be removed to a maximum depth of 2 feet and replaced with granular structural fill. Surface vegetation and other deleterious materials should generally be removed from the site. Topsoil, if encountered, although unsuitable for utilization as structural fill, may be stockpiled for subsequent landscaping purposes. Due to the relatively high groundwater, site grading cuts should be kept to a minimum. Cuts extending to within 1 foot of the groundwater elevation will likely disturb the natural clay soils and proof rolling must not be completed. Stabilization must be anticipated in areas where cuts are to extend to within 1 foot of the groundwater surface. To reduce disturbance of the natural soils during excavation, it is recommended that low-impact, track-mounted equipment with smooth edge buckets/blades be utilized.


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5.3.2 Excavations Temporary construction excavations not exceeding 4 feet in depth, above the water table and through the surface soils, may be constructed with near-vertical sideslopes. Groundwater should be anticipated at a depth of 5.3 feet and possibly shallower. Up to 8 feet through cohesive soils the excavations may be constructed with sideslopes no steeper than one-half horizontal to one vertical (0.5H:1.0V). Excavations deeper than 8 feet are not anticipated. If extensive layers of sandy soils are encountered below the water table, excavation will be very difficult and will require extremely flat sideslopes and/or shoring and bracing. All excavations must be inspected periodically by qualified personnel. If any signs of instability are noted, immediate remedial action must be initiated. The static groundwater table was encountered as shallow as 5.3 feet below the existing surface and may be shallower with seasonal fluctuations. Consideration for dewatering of utility trenches and other excavations below this level should be incorporated into the design and bidding process. 5.3.3 Structural Fill Structural fill will be required as site grading fill, as backfill over foundations and utilities, and possibly as replacement fill below footings. All structural fill must be free of sod, rubbish, construction debris, frozen soil, and other deleterious materials. To stabilize soft subgrade conditions or where structural fill is required to be placed below a level one foot above the water table at the time of construction, a mixture of coarse gravels and cobbles and/or one and one-half to two-inch gravel (stabilizing fill) should be utilized. For structural site grading fill, the maximum particle size should generally not exceed 4 inches; although, occasional particles up to 6 to 8 inches may be incorporated provided that they do not result in “honeycombing” or preclude the obtainment of the desired degree of compaction. Structural site grading fill is defined as fill placed over fairly large open areas to raise the overall site grade. In confined area, the maximum particle size should generally not exceed 2.5 inches. Fine-grained soils (clays and silts) are not recommended as structural fill as they will require careful moisture control placement and compaction. This will be extremely difficult, if not impossible, during the late fall to mid- to late-spring months. 5.3.4 Fill Placement and Compaction Coarse gravel and cobble mixtures (stabilizing fill), if utilized, should be end-dumped, spread to a maximum loose lift thickness of 15 inches, and then compacted by dropping a backhoe bucket uniformly over the surface continuously at least 3 times. As an alternative, the stabilizing fill may be compacted by passing moderately heavy construction equipment or large self-propelled compaction equipment over the surface of each lift at least twice. Subsequent fill material placed


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over the coarse gravels and cobbles should be adequately compacted so that the “fines” are “worked into” the voids in the underlying coarser gravels and cobbles. Structural fill shall be placed in lifts not exceeding 8 inches in loose thickness. Structural fills shall be compacted in accordance with the percent of the maximum dry density as determined by the AASHTO2 T-180 (ASTM3 D1557) compaction criteria in accordance with the following table:

Location Total Fill Thickness

(feet)

Minimum Percentage of Maximum Dry Density

Beneath an area extending at least 5 feet beyond the perimeter of the structure

0 to 8 95

Site Grading Fills Outside area defined above

0 to 5 90

Site Grading fills Outside area defined above

5 to 8 95

Utility Trenches -- 96

Aggregate base -- 96

Subsequent to stripping and prior to the placement of structural site grading fill, the subgrade shall be prepared as discussed in Section 5.3.1, Site Preparation, of this report. Non-structural fill may be placed in lifts not exceeding 12 inches in loose thickness and compacted by passing construction, spreading, or hauling equipment over the surface at least twice. Prior to the placement of structural site grading fill, the subgrade must be prepared as discussed in Section 5.3.1, Site Preparation, of this report. In confined areas, subgrade preparation shall consist of the removal of all loose or disturbed soils. Non-structural fill may be placed in lifts not exceeding 12 inches in loose thickness and compacted by passing construction, spreading, or hauling equipment over the surface at least twice. 5.3.5 Utility Trenches All utility trench backfill material below structurally loaded facilities (flatwork, floor slabs, roads, etc.) should be placed at the same density requirements established for structural fill. If the surface of the backfill becomes disturbed during the course of construction, the backfill should be proof rolled and/or properly compacted prior to the construction of any exterior flatwork over a backfilled trench. Proof rolling may be performed by passing moderately loaded rubber tire-

2 American Association of State Highway and Transportation Officials 3 American Society for Testing and Materials


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mounted construction equipment uniformly over the surface at least twice. If excessively loose or soft areas are encountered during proof rolling, they should be removed to a maximum depth of 2 feet below design finish grade and replaced with structural fill. Most utility companies and City-County governments are now requiring that Type A-1 or A-1a (AASHTO Designation – basically granular soils with limited fines) soils be used as backfill over utilities. These organizations are also requiring that in public roadways the backfill over major utilities be compacted over the full depth of fill to at least 96 percent of the maximum dry density as determined by the AASHTO T-180 (ASTM D1557) method of compaction. We recommend that as the major utilities continue onto the site that these compaction specifications are followed. The natural fine-grained cohesive soils are not recommended for use as trench backfill. The static groundwater table was encountered as shallow as 5.3 feet below the existing surface and may be shallower with seasonal fluctuations. Consideration for dewatering of utility trenches and other excavations below this level should be incorporated into the design and bidding process. 5.4 SPREAD AND CONTINUOUS WALL FOUNDATIONS 5.4.1 Design Data The near-surface natural soils or structural fill extending to suitable natural soils will be suitable of supporting the proposed foundations. For design, the parameters are provided below:

Minimum Recommended Depth of Embedment for Frost Protection - 30 inches

Minimum Recommended Depth of Embedment for

Non-frost Conditions - 15 inches

Recommended Minimum Width for Continuous Wall Footings - 18 inches

Minimum Recommended Width for Isolated Spread

Footings - 24 inches

Recommended Net Bearing Capacity for Real Load Conditions - 2,500 pounds per square foot

Bearing Capacity Increase

For Seismic Loading - 50 percent


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The term “net bearing capacity” refers to the allowable pressure imposed by the portion of the structure located above lowest adjacent final grade. Therefore, the weight of the footing and backfill to lowest adjacent final grade need not be considered. Real loads are defined as the total of all dead plus frequently applied live loads. Total load includes all dead and live loads, including seismic and wind. 5.4.2 Installation Under no circumstances should the footings be underlain be non-engineered fill, sod, rubbish, construction debris, frozen soil, and other deleterious materials. If unsuitable soils are encountered, they must be removed and replaced with compacted granular structural fill. The width of structural replacement fill, as required below footings, should be extended laterally at least 6 inches beyond the edges of the footings in all directions for each foot of fill thickness beneath the footings. For example, if the width of the footing is 2 feet and the thickness of the structural fill beneath the footing is 1 foot, the width of the structural fill at the base of the footing excavation would be a total of 3 feet. 5.4.3 Settlements Settlements of foundations designed and installed in accordance with the above recommendations and supporting maximum projected loads should not exceed 1 inch. Settlements should occur rapidly with approximately 50 to 60 percent of quoted settlements occurring during construction. 5.5 LATERAL RESISTANCE Lateral loads imposed upon foundations due to wind or seismic forces may be resisted by the development of passive earth pressures and friction between the base of the footings and the supporting soils. In determining frictional resistance, a coefficient of 0.40 should be utilized. Passive resistance provided by properly placed and compacted granular structural fill above the water table may be considered equivalent to a fluid with a density of 300 pounds per cubic foot. Below the water table, this granular soil should be considered equivalent to a fluid with a density of 150 pounds per cubic foot. A combination of passive earth resistance and friction may be utilized provided that the friction component of the total is divided by 1.5. 5.6 AT-GRADE SLABS At-grade slabs must be underlain by a minimum of 4 inches of “free-draining” granular material, such as three-quarters to one-inch minus clean gap-graded crushed gravel established over properly prepared subgrade or structural site grading fill extending to suitable natural soils. Under no circumstances should the floor slabs be underlain by non-engineered fill if encountered.


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Settlements of proposed at-grade floor slabs are projected to be less than one-quarter of an inch. Additionally, GSH recommends that floor slabs be constructed a minimum of 4.0 feet from the stabilized groundwater elevation or 1.5 feet if a foundation subdrain system is utilized. As an alternative, site grading fill may be utilized to raise the overall grade to achieve the required separation between the floor slab and the highest groundwater elevation. 5.7 PAVEMENTS The silty clays will exhibit poor pavement support characteristics, particularly when saturated or nearly saturated. For the projected subgrade conditions and traffic conditions, the following pavement sections are recommended:

Parking Areas

(Moderate Volume of Automobiles and Light Trucks with Occasional Medium-Weight Trucks; No Heavyweight Trucks) [1 equivalent 18-kip axle load per day]

Flexible Pavement: 2.5 inches Asphalt concrete

7.0 inches Aggregate base course Over Suitable natural soils and/or structural site

grading fill extending to suitable natural soils

Rigid:

5.0 inches Portland cement concrete

(non-reinforced)




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Driveways, Loading/Unloading Areas, Repair Areas (Moderate Volume of Automobiles and Light Trucks; Moderate Volume of Medium- and Heavyweight Trucks) [5 equivalent 18-kip axle loads per day]

Flexible Pavement: 3.0 inches Asphalt concrete



Rigid:

6.0 inches Portland cement concrete (non-reinforced) 4.0 inches Aggregate base course Over Suitable natural soils and/or structural site


For dumpster pads, we recommend a pavement section consisting of 6.5 inches of Portland cement concrete, 12 inches of aggregate base course, over properly prepared natural subgrade or site grading structural fills. These rigid pavement sections are for non-reinforced Portland cement concrete. Construction of the rigid pavement should be in sections 10 to 12 feet in width with construction or expansion joints or one-quarter depth saw-cuts on no more than 12-foot centers. Saw-cuts must be completed within 24 hours of the “initial set” of the concrete and should be performed under the direction of the concrete paving contractor. The concrete should have a minimum 28-day unconfined compressive strength of 4,000 pounds per square inch and contain 6 percent 1 percent air-entrainment. 5.8 CEMENT TYPES Laboratory tests indicate that the site soils contain negligible amounts of water-soluble sulfates. Therefore, all concrete which will be in contact with the site soils may be prepared using Type I or IA cement.


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5.9 GEOSEISMIC SETTING 5.9.1 General Utah municipalities have adopted the International Building Code (IBC) 2018. The IBC 2018 code refers to ASCE 7-16 Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE 7-16) determines the seismic hazard for a site based upon mapping of bedrock accelerations prepared by the United States Geologic Survey (USGS) and the soil site class. The USGS values are presented on maps incorporated into the IBC code and are also available based on latitude and longitude coordinates (grid points). 5.9.2 Faulting Based upon our review of available literature, no active faults are known to pass through or immediately adjacent to the site. The site is located outside fault investigation zones identified by Cache County. The nearest active fault is the Cache Fault Zone of the Wasatch Fault, approximately 2 miles east of the site. The Wasatch Fault Zone is considered capable of generating earthquakes as large as magnitude 7.34. 5.9.3 Soil Class For dynamic structural analysis, the Site Class D - Default, as defined in Chapter 20 of ASCE 7-16 (per Section 1613.3.2, Site Class Definitions, of IBC 2018) can be utilized. 5.9.4 Ground Motions The IBC 2018 code is based on USGS mapping, which provides values of short and long period accelerations for average bedrock values for the Western United States and must be corrected for local soil conditions. The table on the following page summarizes the peak ground and short and long period accelerations for the MCE event and incorporates the appropriate soil amplification factor for a Site Class D soil profile. Based on the site latitude and longitude (41.7570 degrees north and 111.8281 degrees west, respectively), the values for this site are tabulated on the following page.

4 Arabasz, W.J., Pechmann, J.C., and Brown, E.D., 1992, Observational seismology and the

evaluation of earthquake hazards and risk in the Wasatch Front area, Utah, in Gori, P.L., and Hays, W.W., eds., Assessment of regional earthquake hazards and risk along the Wasatch Front, Utah: U.S. Geological Survey Professional Paper 1500-D, 36 p.


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SpectralAcceleration

Value, T

Peak Ground Acceleration Fa = 1.200

0.2 Seconds (Short Period Acceleration)

SS = 105.8 Fa = 1.200 SMS = 126.9 SDS = 84.6

1.0 Second (Long Period Acceleration)

S1 = 35.2 Fv = 2.000 SM1 = 70.4 SD1 = 46.9

54.8

(% g)class effects]

[adjusted for site DesignValues*(% g)

36.545.7

(% g)[mapped values]

BoundarySite

Coefficient

* IBC 2018/ASCE 7-16 may require a site-specific study based on the project structural engineer’s

evaluation and recommendations. If needed, GSH can provide additional information and analysis including a complete site-specific study.

5.9.5 Liquefaction The site is located in an area that has been identified by Cache County as having a “low” liquefaction potential. Liquefaction is defined as the condition when saturated, loose, granular-type soils lose their support capabilities because of excessive pore water pressure which develops during a seismic event. The majority of the saturated soils encountered in conjunction with this study are cohesive and not susceptible to liquefaction, even during the design seismic event. Analyses indicate isolated zones of the saturated granular soils extended in Boring B-1 will not likely liquefy during the design seismic event. Calculations performed used the procedures described in NCEER-97-0022 entitled, “Proceedings of the NCEER Workshop on Evaluation of Liquefaction Resistance of Soils,” and only apply to the saturated cohesionless deposits. 5.10 SITE VISITS GSH must verify that all topsoil/disturbed soils and any other unsuitable soils have been removed, that non-engineered fills (if encountered) have been removed, and that suitable soils have been encountered prior to placing site grading fills, footings, slabs, and pavements. Additionally, GSH must observe fill placement and verify in-place moisture content and density of fill materials placed at the site.


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5.11 CLOSURE If you have any questions or would like to discuss these items further, please feel free to contact us at (801) 685-9190. Respectfully submitted, GSH Geotechnical, Inc. Reviewed by: Robert A. Gifford Michael S. Huber, P.E. Project Engineer/Geologist State of Utah No. 343650 Vice-President/Senior Geotechnical Engineer RAG/MSH:jlh Encl. Figure 1, Vicinity Map

Figure 2, Site Plan Figures 3A through 3C, Log of Borings Figure 4, Key to Boring Log (USCS) Figure 5, Typical Foundation Chimney Subdrain Detail 18”

Addressee (email)

GOLDENWEST CREDIT UNIONJOB NO. 0645-001-07

REFERENCE:USGS 7.5 MINUTE TOPOGRAPHIC QUADRANGLE MAPTITLED “SMITHFIELD, UTAH” AND “LOGAN, UTAH” BOTH DATED 1998

FIGURE 1VICINITY MAP

1000 10000 2000SCALE IN FEET

SITE

20 200 40SCALE IN FEET

FIGURE 2SITE PLAN

GOLDENWEST CREDIT UNIONJOB NO. 0645-001-07

REFERENCE:ADAPTED FROM DRAWING ENTITLED“CONCEPTUAL SITE PLAN”BY GREAT BASIN ENGINEERING - SOUTH DATED SEPTEMBER 26, 2007

B-3

B-2

B-1

200

EAST

STR

EET

1400 NORTH STREET

BOREHOLE

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Project Name:Location:Drilling Method:Elevation:Remarks:

Project No.:Client:Date Drilled:Water Level:

Gordon Spilker Huber Geotechnical Consultants, Inc.Salt Lake City, Utah 84123

Gra

phic

al L

og

Wat

er L

evel DESCRIPTION

DE

PTH

FT

.

0

5

10

15

20

25

BL

OW

S/FT

SAM

PLE

SY

MB

OL

MO

IST

UR

E (%

)

% P

ASS

ING

200

DR

Y D

EN

SIT

Y(P

CF)

Liq

uid

Lim

it (%

)

Plas

tic L

imit

(%)

REMARKS

The discussion in the text under the section titled, SUBSURFACE CONDITIONS, is necessary for a proper understanding of the nature of the subsurface material.

B-1

Proposed Goldenwest Credit Union Approximately 220 East 1400 North, Logan, Utah

3-3/4" ID Hollow-Stem AugerApproximately 4550' +/-

0645-001-07Goldenwest Credit Union

10-22-079.0' (10-22-07) 5.3 (10-25-07)

Ground SurfaceSILTY CLAYwith trace fine sand; major roots (topsoil) to 2"; trace pinholes; light brown (CL)

CLAYEY SILTwith some fine sand; brown (ML)

37

18

19

32

12.8

23.3

23.4

84

113

105

105

loose to 6"slightly moistvery stiff

moiststiff

saturated

saturatedmedium dense

Stopped drilling at 14.5'.

Stopped sampling at 16.0'.

Installed 1-1/4" diameter slotted PVC pipe to 16.0'.

FIGURE 3A

grades with numerous layers up to 1/4" thick of silty fine sand; without pinholes; brown with oxidation mottling

grades with numerous layers up to 1/4" thick of clayey silts; distorted layers

BOREHOLE

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Gra

phic

al L

og

Wat

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evel DESCRIPTION

DE

PTH

FT

.

0

5

10

15

20

25

BL

OW

S/FT

SAM

PLE

SY

MB

OL

MO

IST

UR

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)

% P

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200

DR

Y D

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SIT

Y(P

CF)

Liq

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Lim

it (%

)

Plas

tic L

imit

(%)

REMARKS


B-2

Proposed Goldenwest Credit UnionApproximately 220 East 1400 North, Logan, Utah



10-22-079.0' (10-22-07) 5.4 (10-25-07)

Ground SurfaceSILTY CLAYwith some fine sand; major roots (topsoil) to 2"; brown (CL)

18

18

12

17.7

26.7

109

99

loose to 6"moiststiff

saturated



Installed 1-1/4" diameter slotted PVC pipe to 11.0'.

FIGURE 3B

grades with oxidation mottling

BOREHOLE

Page: 1 of 1




Gra

phic

al L

og

Wat

er L

evel DESCRIPTION

DE

PTH

FT

.

0

5

10

15

20

25

BL

OW

S/FT

SAM

PLE

SY

MB

OL

MO

IST

UR

E (%

)

% P

ASS

ING

200

DR

Y D

EN

SIT

Y(P

CF)

Liq

uid

Lim

it (%

)

Plas

tic L

imit

(%)

REMARKS


B-3

Proposed Goldenwest Credit Union Approximately 220 East 400 North, Logan, Utah



10-22-07No groundwater encountered (10-22-07)

Ground SurfaceSILTY CLAYwith some fine sand; major roots (topsoil) to 2"; brown with oxidation mottling (CL)

loose to 6"moist"stiff"



No groundwater encountered at time of drilling.

FIGURE 3C

CLIENT: Goldenwest Credit Union

PROJECT: Proposed Goldenwest Credit Union

PROJECT NUMBER: 0645-009-20

① ② ③ ④

CEMENTATION: MODIFIERS:

Trace

<5%

Some

5-12%

With

> 12%

USCS STRATIFICATION:

SYMBOLS

Occasional:

One or less per 6" of thickness

Numerous;

More than one per 6" of thickness

Note: Dual Symbols are used to indicate borderline soil classifications.

⑨

Inorganic Clays of High Plasticity, Fat Clays Thin Wall

OH Organic Silts and Organic Clays of Medium to High Plasticity

HIGHLY ORGANIC SOILS

3.25" OD, 2.42" ID D&M Sampler

OL Organic Silts and Organic Silty Clays o f Low Plasticity3.0" OD, 2.42" ID D&M Sampler

FIGURE 4

KEY TO BORING LOG

⑫

% Passing 200: Fines content of soils sample passing a No. 200 sieve; expressed as a percentage.

CH

(appreciable amount of fines) SC Clayey Sands, Sand-Clay Mixtures Rock Core

PT Peat, Humus, Swamp Soils with High Organic ContentsWATER SYMBOL

Water Level

Inorganic Clays of Low to Medium Plasticity, Gravelly Clays, Sandy Clays, Silty Clays, Lean Clays

FINE-GRAINED

SOILS More than 50% of material is smaller

than No. 200 sieve size.

SILTS AND CLAYS Liquid Limit less than 50%

ML Inorganic Silts and Very Fine Sands, Rock Flour, Silty or Clayey Fine Sands or Clayey Silts with Slight Plasticity

No Recovery

CL

SILTS AND CLAYS Liquid Limit greater than

50%

MH Inorganic Silts, Micacious or Diatomacious Fine Sand or Silty Soils

California Sampler

SP Poorly-Graded Sands, Gravelly Sands, Little or No Fines Bulk/Bag Sample

SANDS WITH FINES SM Silty Sands, Sand-Silt Mixtures

Standard Penetration Split Spoon Sampler

(appreciable amount of fines) GC Clayey Gravels, Gravel-Sand-Clay Mixtures TYPICAL SAMPLER

SANDS More than 50%

of coarse fraction passing through No. 4

sieve.

CLEAN SANDS SW Well-Graded Sands, Gravelly Sands, Little or No FinesGRAPHIC SYMBOLS

(little or no fines)

Seam up to 1/8"

Layer 1/8" to 12"

(little or no fines) GP

Poorly-Graded Gravels, Gravel-Sand Mixtures, Little or No Fines

GRAVELS WITH FINES GM Silty Gravels, Gravel-Sand-Silt Mixtures

Descriptions and stratum lines are interpretive; field descriptions may have been modified to reflect lab test results. Descriptions on the 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.

UN

IFIE

D S

OIL

CL

AS

SIF

ICA

TIO

N S

YS

TE

M (

US

CS

)

MAJOR DIVISIONS TYPICAL DESCRIPTIONS DESCRIPTION THICKNESS

COARSE-GRAINED

SOILS More than 50% of material is larger than No. 200

sieve size.

GRAVELS More than 50%

of coarse fraction retained on No. 4 sieve.

CLEAN GRAVELS GW Well-Graded Gravels, Gravel-Sand Mixtures, Little or No Fines

Moist: Damp but no visible water.

⑦Moisture (%): Water content of soil sample measured in laboratory; expressed as percentage of dryweight of Strongly: Will not crumble or break with

finger pressure.Saturated: Visible water, usually soil below water table.

⑧Dry Density (pcf): The density of a soil measured in laboratory; expressed in pounds per cubic foot.

⑤Blow Count: Number of blows to advance sampler 12" beyond first 6", using a 140-lb hammer with 30" drop.

MOISTURE CONTENT (FIELD TEST):

Weakly: Crumbles or breaks with handling or slight finger pressure.

Dry: Absence of moisture, dusty, dry to the touch.

⑥Sample Symbol: Type of soil sample collected at depth interval shown; sampler symbols are explained below. Moderately: Crumbles or breaks with

considerable finger pressure.

⑪Plasticity Index (%): Range of water content at which a soil exhibits plastic properties.

③Description: Description of material encountered; may include color, moisture, grain size, density/consistency,

⑫Remarks: Comments and observations regarding drilling or sampling made by driller or field personnel. May include other field and laboratory test results using the following abbreviations:

④ Depth (ft.): Depth in feet below the ground surface.

DESCRIPTION REMARKS

⑤ ⑥ ⑦ ⑧ ⑨ ⑩ ⑪

COLUMN DESCRIPTIONS

①Water Level: Depth to measured groundwater table. See symbol below.

⑩Liquid Limit (%): Water content at which a soil changes from plastic to liquid behavior.

②USCS: (Unified Soil Classification System) Description of soils encountered; typical symbols are explained below.

WA

TE

R L

EV

EL

USCS D

EP

TH

(FT

.)

BL

OW

CO

UN

T

SA

MP

LE

SY

MB

OL

MO

IST

UR

E (%

)

DR

Y D

EN

SIT

Y (

PC

F)

% P

AS

SS

ING

200

LIQ

UID

LIM

IT (%

)

PL

AS

TIC

ITY

IN

DE

X

FIGURE 5

0

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