171419 USDA AMES Building Addition Geotech Report.pdf

ALLENDER BUTZKE ENGINEERS INC.

GEOTECHNICAL ENVIRONMENTAL CONSTRUCTION Q. C.

3660 109TH STREET URBANDALE, IOWA 50322 PHONE 515-252-1885 FAX 515-252-1888

November 30, 2017 PN 171419

GEOTECHNICAL EXPLORATION

USDA BUILDING 21 ADDITION

USDA AMES LABORATORRY, 1920 DAYTON AVENUE

AMES, IOWA

PERFORMED FOR

STANLEY CONSULTANTS, INC.

100 COURT AVENUE, SUITE 300

DES MOINES, IA 50309

USDA LABORATORY, 1920 DAYTON AVENUE

PN 171419

TABLE OF CONTENTS

PROJECT INFORMATION

FIELD EXPLORATION

SUBSURFACE CONDITIONS

Site Geology

Soil Profile

Groundwater Level Observations

ANALYSES AND RECOMMENDATIONS

Existing Fill

Moderately Expansive Soil

Site Grading

Excavation Stability and Dewatering

Seismic Site Classification

Foundation Design

Floor Slab Support

Lateral Earth Pressures

GENERAL

USDA LABORATORY, 1920 DAYTON AVENUE

November 30, 2017

PROJECT INFORMATION

United States Department of Agriculture (USDA) plans to construct a two-story, 13,800 square feet plan area building addition to the existing Building 21 located at the USDA Laboratory in

Ames, Iowa. The building addition will be located in an existing courtyard area on the north side of lab Building 21, immediately west of the corridor connecting Buildings 20 and 21 (see Figure No. 1).

Preliminary structural loads were provided by Stanley Consultants who indicated that the proposed

2-story slab-on-grade, steel framed structure will generate maximum column loads on the order of

120 kips. The building addition will have a finish floor elevation (FFE) to match that of the existing building near 995.25 feet. Based on this information we expect that cut depths and fill thicknesses of less than 3 feet will be required to achieve desired final grades.

Figure No. 1 – Project Site Location Map

Project Site

FIELD EXPLORATION

Four borings were conducted at this site to depths of 20 and 30 feet below existing grades on

November 13, 2017. Approximate locations of the borings are shown in the following Figure No. 2 and on the enclosed Site Plan and were measured in the field from existing landmarks. Boring locations and ground surface elevations were determined using GPS survey equipment. The boring surface elevations, indicated on the enclosed Boring Logs, were Iowa Real-Time Network (RTN) derived. Methods of drilling, sampling, standard laboratory testing, and classifying of subsurface materials are discussed in the Boring Log Description/Legend pages of the Appendix.

Figure No. 2 – Boring Location Map

SUBSURFACE CONDITIONS

Site Geology

This project site is located within a geomorphic region known as the “Des Moines Glacial

Lobe.” The Wisconsinan glacier was the last glacier to advance into north central Iowa. Wisconsinan glacial till present near the surface typically consists of sandy lean clay with random zones of high sand and silt content. Fine grained deposits of locally derived alluvium are commonly encountered at the surface in isolated upland depressions. The deeper Wisconsinan subglacial till consists of a more homogeneous mixture of sand, silt and clay. It is not uncommon to encounter relatively thick sand layers, termed glacial outwash deposits, within the glacial till formation.

Soil Profile

Detailed descriptions of soils encountered by this exploration are provided on the Boring

Logs enclosed in the Appendix. The Profile of Borings (Plate A-1) presented in the Appendix depicts the relative deposit elevations in the borings. Following is a discussion of the subsurface materials encountered in the borings. Unless otherwise indicated, the depths of soil strata and groundwater levels are referenced from below existing grade at the individual boring locations at the time of drilling.

Existing fill comprised of brown-gray to dark brown lean clay (CL) and lean to fat clay (CL-

CH) was encountered at the ground surface in each of the borings. In Boring Nos. 2 and 3, a layer of crushed rock with fines, approximately 0.5 and 1 feet thick, respectively, was encountered within the existing fill near respective depths of 1.3 and 1 feet. The moist and stiff fill encountered in the borings extended to depths of 2.5 to 4 feet.

Very dark gray to gray lean to fat clay (CL-CH) local alluvium was encountered underlying the fill in Boring Nos. 1, 3, and 4. The moist to very moist and medium stiff local alluvium extended to depths near 6.5 to 10 feet.

Wisconsinan glacial till consisting of sandy lean clay (CL) with trace amounts of gravel was encountered underlying the existing fill in Boring No. 2 and underlying the local alluvium in the remaining borings. The upper portion of the glacial till was generally moist to very moist and medium stiff to stiff, becoming stiff to very stiff and grading to dark gray below depths of 13 to 14 feet. The borings terminated in the stiff to very stiff glacial till near depths of 20 and 30 feet.

Groundwater Level Observations

The borings were monitored during and shortly after drilling operations to detect moisture seepage and groundwater accumulation. The results of our water level observations are noted on the

Boring Logs enclosed in the Appendix.

During drilling operations, moisture seepage was encountered near a depth of 9 feet in Boring

Nos. 3 and 4. Shortly after drilling operations, groundwater accumulation was observed near respective depths of 13 and 16 feet in Boring No. 3 and 4. No moisture seepage or ground water accumulation was noted in Boring Nos. 1 and 2. It should be recognized that these short-term water levels are not necessarily a true indication of the groundwater table. Long-term observations would be necessary to accurately define the groundwater variations at this site.

Brown-gray and gray coloring of the Wisconsinan glacial till and local alluvium is an indication of past fluctuations of the groundwater in this zone. Therefore, we interpret that past seasonal high water tables have been near depths of 4 feet below existing grades. Fluctuation of groundwater levels can occur due to seasonal variations in the amount of rainfall, surface drainage, subsurface drainage, site topography, irrigation practices, and ground cover (pavement or vegetation).

ANALYSES AND RECOMMENDATIONS

Existing Fill

Existing fill was encountered at the surface of the borings and extended to depths between

2.5 to 4 feet below existing grades. The fill generally consisted of lean clay and lean to fat clay soils with varying amounts of sand, gravel, and crushed rock. Layers of crushed rock with fines were also observed within the fill in 2 of the four borings. Although the boring information suggests that the existing fil was generally damp to moist and exhibited stiff consistencies, based on our past experience at this facility, undocumented fill and buried waste at the site can be quite variable and other undocumented fill exhibiting less desirable support characteristics could be present in other unexplored areas. Therefore we recommend all existing fill below the proposed addition be completely over-excavated and replaced with engineered compacted fill during initial site preparation. Existing storm sewer, gas lines, and other utilities below the addition should also be relocated and removed during initial site preparation. The lean to fat clay (CL-CH) existing fill is considered moderately expansive and clean portions of the fill may be utilized as engineered fill placed 2 feet or more below the bottom of floor slab as recommended in the following Moderately

Expansive Soil section of this report.

Prior to the removal of the existing fill and before any new fill is placed, the organic and loose materials in addition to all vegetation must be stripped. We expect that a minimum stripping depth of 6 inches will be required. The stripping depths may vary due to localized variations in vegetation cover and subgrade stability. The strippings could be used for landscaping purposes in non-critical areas where support for foundations and floor slabs is not required. Root balls and large roots from mature trees are also to be completely removed. We recommend that geotechnical probing, testing, and technical observations be conducted by an ABE geotechnical representative during site preparation and over-excavation of the existing fill to further evaluate the suitability and extent of the existing fill soils.

Moderately Expansive Soil

The lean to fat clay (CL-CH) existing fill and local alluvium soils encountered in the upper 4 to 10 feet of the borings are moderately plastic (Liquid Limits (LL) of 48 to 49 and Plasticity Indices

(PI) of 27 to 30) and are considered moderately expansive. These soils are subject to moderate volumetric change with varying soil moisture contents which can cause movement and distress to lightly loaded footings, floor slabs, and pavements. The most severe problems occur where higher clay content soils (CL-CH) are in a natural state of low moisture or are highly compacted at moisture contents near or below optimum moisture content on a relatively incompressible base. Subsequent moisture content increases below the floor slab or pavement after construction then cause the moderately expansive soils to swell appreciably. If the moisture content does not fluctuate much, then the soil swelling and heave will be minor. Our experience indicates that typical load bearing foundation pressures can generally resist swell pressures associated with moderately expansive soils.

To reduce the potential for future floor slab movement due to moderately expansive soils, we recommend floor slabs bear on a minimum of 2 feet of low plasticity cohesive (LL of 45 or less and

PI of 23 or less) or cohesionless soils. This recommendation will require that engineered fill to replace existing fill below the proposed addition, as recommended in the preceding Existing Fill section, be suitable low plasticity materials. Based on boring information, suitable low plasticity materials will not likely be available on-site and low plasticity borrow materials will likely need to be imported for use as engineered fill within 2 feet below the floor slab.

While over-excavating moderate plasticity soils and providing a low plasticity buffer generally reduces future movements to acceptable levels, this method does not necessarily eliminate all movements. For this reason, it is advisable to design the slab-on-grade floors slabs to "float" free of edge-restraint at walls and columns, and to provide vertical space for movement of any non-load bearing walls setting on the slabs. Thicker low plasticity buffers would further reduce the risk of floor movement.

Newly planted vegetation (trees and shrubs) or the existing vegetation close to the building may remove moisture from the nearby soils. Foundations and floor slabs can potentially settle due to shrinkage of soils beneath the footings and floor slabs as the soils dry, especially during drought periods when mature trees compete for moisture from nearby soils. As a rule of thumb, trees and shrubs should be kept a minimum horizontal distance away from the building equal to the ultimate height of the vegetation. Likewise, irrigation next to the building should be limited since it can contribute to soil swelling.

Site Grading

We recommend that low plasticity (LL ≤ 45, PI ≤ 23) cohesive or cohesionless soils, free of rubble and organics, be used as compacted fill. Based on the borings, the majority of soil anticipated in the shallow excavations at the site is considered moderately expansive and should not be used as engineered fill within 2 feet beneath the bottom of floor slabs. Due to the low availability of low plasticity soil onsite, it is likely that suitable fill material will need to be imported to the site.

Potential borrow materials should be tested by ABE prior to importing to ensure suitability for use as low plasticity fill.

The following Table A lists recommended minimum compaction requirements for cohesive and cohesionless fill materials in specific applications. For cohesive soils, moisture contents within a range of -1 to +4 percent of the material's optimum moisture content are necessary to achieve the desired fill qualities. Inorganic portions of the moderately expansive lean to fat clay (CL-CH) fill and local alluvium may be utilized as compacted fill at a depth of 2 feet or more below the bottom of floor slab.

TABLE A

RECOMMENDED DEGREE OF COMPACTION GUIDELINES

Construction

Application

Standard Proctor

(ASTM D698)

Cohesive Soil

Standard Proctor

(ASTM D698)

Cohesionless Soil

*Relative Density

(D4253 & D4254)

Cohesionless Soil

Class 1 95% 98% 70%

Class 2 90% 93% 45%

Class 3 85% 88% 20%

Class 1 - Subgrade for building foundations, slabs-on-grade, pavements and other critical backfill areas.

Class 2 - Backfill adjacent to structures not supporting other structures - Minor subsidence possible.

Class 3 - Backfill in non-critical areas - Moderate subsidence possible.

*Use Relative Density technique (ASTM D4253 & D4254) where Standard Proctor technique (ASTM D698) does not result in a definable maximum dry density and optimum moisture content.

The on-site soils can be excavated utilizing conventional excavation equipment. Granular soils can generally be suitably compacted with vibratory compaction equipment whereas cohesive soils are more suitable for compaction with sheepsfoot or pneumatic type compactors. Care should be exercised in properly backfilling and compacting all trenches, especially utility trenches under or adjacent to the pavement. Loosely compacted or sand backfilled trenches can collect surface water and inadvertently direct it to the pavement subgrade and cause softening of the soil as well as increasing frost heave potential.

At the time of this geotechnical exploration, moisture content of the existing fill was generally below the recommended moisture content range. Depending upon precipitation levels prior to and during construction, adjustment of soil moisture content may be required in order to lower or raise the moisture to within the recommended moisture content range. Discing and aeration is generally the most economical method to lower soil moisture content, if climatic conditions allow.

Chemical modification of very moist soils with quicklime or Class C fly ash can be accomplished if construction scheduling does not permit field drying. If grading or fill placement at the site will be conducted during colder weather, it should be noted that common chemical modification methods may not be reactive when temperatures are near or below 40° Fahrenheit.

Excavation Stability and Dewatering

Excavations at the site will encounter predominately cohesive soils with the possibility of wet sand seams or granular fill layers within the existing fill, local alluvium, and Wisconsinan glacial till.

If excavations encounter only cohesive soils with no wet sand seams or layers, it is expected that the water seepage can be controlled by permitting it to drain into temporary construction sumps and be pumped outside the perimeter of the excavations. More extensive dewatering such as sand points and wells may be required for excavations which extend down into water bearing sand layers. We recommend that prior to excavating in saturated sand, water levels be lowered and maintained 2 feet or more below the bottom of excavations to prevent upward seepage forces which could reduce subgrade support.

The extent of bracing or sloping of open cut excavations will be dependent upon depth of cut, groundwater conditions, soils encountered, length of time the excavation will be open, area available for excavation and local governing regulations. Predominately cohesive soils may appear to stand nearly vertical in shallow excavations for short periods of time. However, soil creep, surcharge loads, precipitation, subsurface moisture seepage, construction activity vibrations and other factors may cause these soils to cave within an unpredictable period of time. Excavations encountering sand or loose fill may tend to cave rapidly, especially if water is flowing through these materials. Unstable granular excavation walls may also cause surrounding cohesive soils to become unstable. Temporary shoring, flattening of the excavation slopes or use of trench boxes may be required to maintain a safe condition. It is to be noted that provisions for shoring and bracing of deep excavations are required of the contractor by OSHA.

Seismic Site Classification

Boring information indicates the soil profile at this site consists primarily of medium stiff to stiff fill, local alluvium, and Wisconsinan glacial till. Very stiff Wisconsinan glacial till soils were encountered below approximate depths of 10 to 15 feet. Based on our past experience at the site, the very stiff Wisconsinan glacial till soils are underlain by very stiff loess and Pre-Illinoian glacial till extending to depths on the order of 70 to 80 feet or more. Publicly available records for a well located on the site indicates the overburden soils are underlain by shale, sandstone, and limestone bedrock. Based on this information, we estimate the project site to be Site Class C as defined in the

2015 International Building Code (IBC) and 2010 ASCE-7 Standard. IBC 2015 Figures 1613.3.1 (1) and (2), Tables 1613.3.3 (1) and (2), and information obtained from the U.S. Geological Survey indicate the site coefficients for mapped spectral response acceleration at short period (Fa) equal to

1.2 and at 1-sectond (Fv) equal to 1.7 could be utilized for this project.

Foundation Design

In our opinion, new engineered fill placed in association with removal and replacement of existing fill and stiff natural soils can provide adequate support for the proposed structure. We recommend that continuous and isolated spread foundations bearing on suitable soils be proportioned for maximum net allowable soil bearing pressures of 2,000 pounds per square foot. We estimate long-term total settlements due to structural loads will be less than 1 inch and differential settlement may be on the order of ½ of the total settlement when foundations bear on newly placed engineered compacted fill that has replaced existing fill soils and suitable natural soils. Structural and architectural connections should be designed to accommodate the differential settlement that may occur between the existing building and the new addition.

Continuous foundations should be adequately reinforced to limit deflections caused by non-uniform soil support characteristics. All exterior foundations and foundations in unheated areas should be placed a minimum of 3.5 feet below final grade to provide protection against frost penetration and reduce movements associated with changes in soil moisture content. Foundation excavations should be conducted in a manner that avoids disturbance of soils below the existing foundations. The on-site cohesive soils and newly placed cohesive fill would be suitable for trench foundations. Footing excavations should be kept free of water accumulation to prevent softening of subgrade soils.

Observations and test probing of the foundation subgrade soils should be conducted by an

ABE geotechnical engineer to determine that the soils are compatible with the design criteria. If zones of soft or otherwise unsuitable soils are encountered at foundation level, we recommend that footings be extended to bear on firmer soils or an over-excavation and compacted backfill procedure be implemented. Over-excavations should extend 9 inches laterally in each direction beyond the foundation edges for each foot of over-excavation depth.

Floor Slab Support

As previously discussed in the Existing Fill and Moderately Expansive Soils sections, floor slabs can be supported on new engineered fill placed in association with over-excavation of undocumented existing fill soils below the addition. Fill placed within 2 feet below the floor slab should consist of low plasticity (LL ≤ 45, PI ≤ 23) cohesive or cohesionless materials.

Floor slabs can be designed for a modulus of subgrade reaction value of 125 pounds per cubic inch when bearing on the recommended prepared subgrade. By choosing to not remove and either recompact or replace the existing fill below the building addition, the owner would be accepting the potential risk of unpredictable floor slab settlement and possible cracking. Testing, observations, and probing should be conducted during construction to delineate zones of soft soils which may require repair prior to concrete placement.

Lateral Earth Pressures

Walls constructed to retain soil should be designed to accommodate unbalanced lateral earth pressures. Estimated lateral earth pressures for cohesive and cohesionless (granular) backfill are presented in the following Table B. Active earth pressure design assumes that the wall can rotate and deflect at the top. If the wall is rigidly fixed, higher lateral earth pressures will develop against the wall and at-rest pressure parameters should be used for design. Increased earth pressures can also develop from restricted soil drainage, surcharge loads adjacent to the wall, and compaction of the adjacent backfill. Expansive materials (CH), either natural or backfill, should not be within 3 feet of below grade walls.

A coefficient of sliding friction value of 0.3 may be used for P.C. concrete on a cohesive subgrade. This ultimate value assumes no safety factor and design with this ultimate value should include a minimum factor of safety of 1.5.

Cohesionless (granular) backfill lateral earth pressure parameters may be used where granular backfill is installed behind the subsurface wall in accordance with the following Figure No. 3. The granular backfill should have a minimum width of 2 feet and be wide enough to accommodate the back slope limit line of 2:1 (vertical to horizontal) or flatter. The area between the required minimum zone of granular material and the actual limits of excavation may be backfilled with either cohesive or granular soils.

TABLE B

LATERAL EARTH PRESSURE PARAMETERS

Condition

Cohesive Soil

(non-expansive clay)

Cohesionless Soil

(granular-sand)

Assumed Backfill Characteristics

Approximate Total Density

Approximate Friction Angle

Active Pressure Coefficient, Ka

At-Rest Pressure Coefficient, Ko

Passive Pressure Coefficient, Kp

130 pcf

15o - 20o

0.5

0.7

120 pcf

30o - 35o

0.3

0.5

3.3

Estimated Lateral Earth Pressure1 (Equivalent Fluid Pressures)

Active - Drained

Active - Undrained2

65 pcf

95 pcf

35 pcf

80 pcf

At-Rest - Drained

At-Rest - Undrained2

90 pcf

110 pcf

60 pcf

90 pcf

Passive - Drained

Passive - Undrained3

260 pcf

135 pcf

400 pcf

190 pcf

1) Assumes no safety factor, negligible wall friction, vertical wall, level backfill, zero surcharge loads and ignores cohesion shear strength.

2) Combined buoyant backfill unit weight and hydrostatic (water @ 62.4 pcf) loading.

3) Excludes hydrostatic loading.

Figure No. 3: Lateral Earth Pressures Example Section

Walls retaining fine-grained soils, and subjected to seasonally depressed temperatures, may be subject to long-term accumulative movement due to soil creep and freeze-thaw action. It is desirable to use free draining granular backfill behind such walls to minimize this movement. We recommend that a chimney of clean granular material (similar to Iowa DOT Specification 4131) be placed directly against the back of these walls and that the chimney be connected to a drain system.

An acceptable drain system may be constructed using perforated pipe encased in clean granular material and sloped to sumps or storm drains.

GENERAL

The analyses and recommendations in this report are based in part upon the data obtained from the soil borings performed at the indicated locations and from any other information discussed in this report. This report does not reflect any variations which may occur between borings or across the site. The nature and extent of such variations may not become evident until construction. If variations then appear evident, it will be necessary to reevaluate the recommendations of this report.

It is recommended that the geotechnical engineer be provided the opportunity to review the plans and specifications so that comments can be made regarding the interpretation and implementation of our geotechnical recommendations in the design and specifications. It is further recommended that the geotechnical engineer be retained for testing and observation during earthwork and foundation construction phases to help determine that the design requirements are fulfilled.

This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranty, expressed or implied, is made. In the event that any changes in the nature, design or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and the conclusions of this report modified or verified in writing by the geotechnical engineer.

The scope of our service was not intended to include any environmental assessment or exploration for the presence of hazardous or toxic materials in the soil, surface water, groundwater or air on, below or adjacent to this site.

APPENDIX

BORING LOG DESCRIPTION/LEGEND

(page 1 of 3)

The material types encountered during the drilling operations were recorded on field logs. The profile represented on the

Boring Log is based on final classification performed by a geotechnical engineer using the field logs, laboratory observation and testing. The material stratigraphy demarcation lines shown on the Boring Logs indicate changes in soil characteristics, however, actual soil changes or variations may occur as a gradual transition. Soil profile discussion, Log Boring information, water levels and recommendations presented in this report are based upon measured depths below ground levels existing at time of the field exploration, unless otherwise specified.

DRILLING AND SAMPLING

The borings were conducted with either a truck or all-terrain rotary drill rig using the drilling methods indicated on each Boring Log. Soil sampling and/or in-situ testing such as Shelby Tube (ST), split-spoon (SS), drive cone (DC), or core (C) was conducted at depth intervals which were selected in consideration of the characteristics of the proposed construction. Generally undisturbed soil samples are taken at 5 foot depth intervals or change in soil types. Disturbed soil samples from the auger, either jar size or bulk size samples, may be taken at intermediate intervals for the purpose of soil classification or laboratory testing. Borings conducted for soil classification only, will show no designation of sampling although disturbed sampling is performed. Soil samples obtained in the field were identified and sealed for transportation to the laboratory for performance of pertinent physical testing and engineering classification.

Drilling Methods

CFA - Continuous Flight Auger: 4, 6, or 8-inch diameter (ASTM D1452).

RD - Rotary Drilling: Using drilling fluid in cased or uncased boring (ASTM D2113).

HSA - Hollow Stem Auger: 6 or 8-inch diameter, continuous flight auger remains in boring with soil removed from the hollow stem through which undisturbed sampling is conducted.

HA - Hand Auger: 4-inch or less diameter.

Sample Types

ST - Shelby Tube: Thin-walled tube samples of cohesive soils (ASTM D1587).

SS - Split Spoon with 140 lb. manual hammer: Standard penetration test and split-barrel samples (ASTM D1586).

SSA - Split Spoon with 140 lb. automatic hammer: Standard penetration test and split-barrel samples (ASTM D1586).

DC - Drive Cone: Dynamic in-place testing of soil using a 2-inch diameter cone with a 60 degree point driven into the soil for continuous 1-foot intervals in the same manner as Split Spoon, no sample is obtained.

C - Core: Sampling hard soil or bedrock with a diamond core barrel in a rotary drill boring (ASTM D2113).

SPT - Standard Penetration Test: Number of blows required to drive sampler (split spoon or drive cone) into the soil with a 140-pound weight dropping a distance of 30-inches (ASTM D1586), number of blows recorded for each 6-inch interval in an 18-inch (or more) penetration depth, values shown are for each 6-inch interval (if series of number sets are shown) or a total of the last two 6-inch intervals (if only one number is shown) which is commonly referred to as "N" in blows per foot. High resistance is indicated by a high number of blows for a lesser penetration depth listed in inches.

BS - Bulk Sample: Disturbed.

CPT - Cone Penetration Test: Quasi-static in-place testing of soils using a 60 degree cone and friction sleeve which are steadily pushed into the soil and measure skin friction and end bearing (ASTM D3441).

STANDARD LABORATORY TESTING

Representative undisturbed soil samples obtained by the Shelby Tube sampler were tested for moisture content (ASTM D2216), density (dry) and unconfined compressive strength (ASTM D2166) in the laboratory. Results of these tests appear on the respective Boring Logs. Additional soil testing including particle size analysis (ASTM D422) and Atterberg Limits (ASTM D4318) may be conducted, if necessary, to define in more detail pertinent soil characteristics for classification in accordance with the Unified Soil Classification System. Specialized laboratory tests (if conducted) to determine pertinent soil characteristics are discussed in the "Laboratory Testing" section of the report.

WATER LEVEL MEASUREMENT

Water levels indicated on the Boring Logs are the levels measured in the borings at the times indicated. In pervious soils, the indicated levels may reflect the location of groundwater. In low permeability soils, the accurate determination of groundwater levels is not possible with short term observations.

(page 2 of 3)

DESCRIPTIVE SOIL CLASSIFICATION

Soil description is based on the Unified Classification System as outlined in ASTM Designations D-2487 and D-2488. This classification is primarily based upon visual and apparent physical soil characteristics, comparison with other soil samples, and our experience with the soil. Additional laboratory testing may be conducted, if necessary to define in more detail pertinent soil characteristics. The Unified Soil Classification group symbol shown on the boring logs corresponds with the group names listed below. The description includes soil constituents, moisture conditions, color and any other appropriate descriptive terms.

Group Symbol

Group Name Group Symbol

Group Name Group Symbol

Group Name Group Symbol

Group Name

GW

Well-Graded

Gravel

SW

Well-Graded Sand

CL Lean Clay CH Fat Clay

GP

Poorly-Graded

Gravel

SP

Poorly-Graded Sand

ML Silt MH Elastic Silt

GM Silty Gravel SM Silty Sand OL Organic Clay Organic Silt

OH

Organic Clay Organic Silt

GC

Clayey Gravel

SC Clayey Sand PT Peat

RELATIVE PROPORTIONS

GRAIN SIZE TERMINOLOGY

Descriptive Term(s) (Of components also present in sample)

Sand and Gravel % of Dry Weight

Fines % of Dry Weight

Major Component of Sample

Size Range

Trace <15 <5 Cobbles 12 in. to 3 in.

(300mm to 75mm)

With 15-30 5-12 Gravel 3 in. to #4 sieve

(75mm to 4.75mm)

Modifier >30 >12 Sand #4 to #200 sieve

(4.75mm to 0.074mm)

Silt or Clay Passing #200 sieve

(.074 mm)

CONSISTENCY OF FINE-GRAINED SOILS

RELATIVE DENSITY OF

COARSE-GRAINED SOILS

Unconfined Compressive Strength, Qu, psf Consistency SPT, bpf SPT, bpf Relative Density

< 500 Very Soft 0-2 0-4 Very Loose

500-1,000 Soft 2-4 4-10 Loose

1,000-2,000 Medium Stiff 4-8 10-30 Medium Dense

2,000-4,000 Stiff 8-15 30-50 Dense

4,000-8,000 Very Stiff 15-30 50-80 Very Dense

8,000-16,000 Hard 30-100 80+ Extremely Dense

> 16,000 Very Hard >100

(page 3 of 3)

ABBREVIATIONS

COMMONLY USED ABBREVIATIONS

ft. or ' - feet elev. - Elevation

in. or " - inches

% - Percent psf - pounds per square foot

No. - Number plf - pound per lineal foot

TB - Test Boring pcf - pounds per cubic feet

N - blow count (SPT, bpf) kip - 1000 pounds

USCS - Unified Soil Classification System ksf - 1000 pounds per square foot

LL - Liquid Limit klf - 1000 pounds per lineal foot

PL - Plastic Limit tsf - tons per square foot

PI - Plasticity Index bpf - blows per foot (SPT, N)

SSA

ST

SSA

ST

ST

ST

ST

ST

14.9

18.4

20.2

15.9

13.3

12.5

12.7

10.7

10,900

Dark brown with brown-gray sandy lean to fat clay, trace gravel and crushed rock, damp

FILL

LL = 48, PI = 27

Very dark gray lean to fat clay with sand, trace organics, moist Dark gray to gray sandy lean to fat clay, trace gravel after 4.5'

LOCAL ALLUVIUM

Brown-gray sandy lean clay, trace gravel, moist to very moist

Moist after 14.5'

Dark gray after 17'

WISCONSINAN GLACIAL TILL

End of Boring

CL-

CH

CL-

CH

CL

BORING LOG NO. 1 Project No.: 171419

Project: USDA Building 21 Renovation and Client: Stanley Consultants, Inc.

USDA Ames Laboratory, 1920 Dayton 100 Court Ave, Suite 300 Ames, Iowa Des Moines, IA 50309

Surface Elevation: 996.0' Date Drilled: 11/13/17 Drilling Method: 4" CFA Datum: GPS Survey Drilling Depth, ft.: 30 Page: 1 of

*The stratification lines represent the approximate boundary lines between material types: in-situ, the transition may be gradual.

Water Level Observation

ALLENDER BUTZKE ENGINEERS, INC.Time: at completion hrs. days Depth to Geotechnical | Environmental | Construction Q.C.water: Dry ft. ft. ft.

E le va tio n ft.

D ep th ft.

S am pl e

N o.

Ty pe

S P

T bp f

M oi st ur e C on te nt

D ry

D en si ty pc f

U nc on fin ed C om pr es si ve S tre ng th ps f Material Description*

G ra ph ic

Lo g

U S

C S

W at er L ev el

D ep th

E le va tio n ft.

SSA

SSA

ST

ST

ST

ST

ST

12.3

17.6

16.4

14.5

15.8

12.8

11.8

Dark brown sandy lean to fat clay, moist

Crushed rock with fines from 1.3' to 1.8'

FILL

Brown-gray sandy to very sandy lean clay, trace gravel, moist

WISCONSINAN GLACIAL TILL

Dark gray after 14'

End of Boring

CL-

CH

CL

990.8

974.8

BORING LOG NO. 2 Project No.: 171419

Project: USDA Building 21 Renovation and Client: Stanley Consultants, Inc.

USDA Ames Laboratory, 1920 Dayton 100 Court Ave, Suite 300 Ames, Iowa Des Moines, IA 50309

Surface Elevation: 994.8' Date Drilled: 11/13/17 Drilling Method: 4" CFA Datum: GPS Survey Drilling Depth, ft.: 20 Page: 1 of

*The stratification lines represent the approximate boundary lines between material types: in-situ, the transition may be gradual.

Water Level Observation

ALLENDER BUTZKE ENGINEERS, INC.Time: at completion hrs. days Depth to Geotechnical | Environmental | Construction Q.C.water: Dry ft. ft. ft.

E le va tio n ft.

D ep th ft.

S am pl e

N o.

Ty pe

S P

T bp f

M oi st ur e C on te nt

D ry

D en si ty pc f

U nc on fin ed C om pr es si ve S tre ng th ps f Material Description*

G ra ph ic

Lo g

U S

C S

W at er L ev el

D ep th

E le va tio n

SSA

SSA

ST

ST

ST

ST

ST

13.0

26.2

17.6

15.9

16.9

13.3

12.0

Dark brown sandy lean to fat clay with crushed rock, moist Crushed rock with fines from 1' to 2'

FILL

Very dark gray lean to fat clay, very moist to moist

LOCAL ALLUVIUM

Brown-gray sandy lean clay, trace gravel, moist

Moisture seepage near and very moist after 9' Saturated clayey sand seam from 10' to 10.5' Brown-gray sandy lean clay, moist after 10.5'

WISCONSINAN GLACIAL TILL

Dark gray after 17.5'

End of Boring

CL-

CH

CL-

CH

CL

SC

3.5 993.6

6.5 990.6

977.1

BORING LOG NO. 3 Project No.: 171419

Project: USDA Building 21 Renovation and Client: Stanley Consultants, Inc.

USDA Ames Laboratory, 1920 Dayton 100 Court Ave, Suite 300 Ames, Iowa Des Moines, IA 50309

Surface Elevation: 997.1' Date Drilled: 11/13/17 Drilling Method: 4" CFA Datum: GPS Survey Drilling Depth, ft.: 20 Page: 1 of

*The stratification lines represent the approximate boundary lines between material types: in-situ, the transition may be gradual.

Water Level Observation

ALLENDER BUTZKE ENGINEERS, INC.Time: at completion hrs. days Depth to Geotechnical | Environmental | Construction Q.C.water: 13 ft. ft. ft.

E le va tio n ft.

D ep th ft.

S am pl e

N o.

Ty pe

S P

T bp f

M oi st ur e C on te nt

D ry

D en si ty pc f

U nc on fin ed C om pr es si ve S tre ng th ps f Material Description*

G ra ph ic

Lo g

U S

C S

W at er L ev el

D ep th

E le va tio n

SSA

ST

ST

ST

ST

ST

ST

11 16.7

26.1

25.7

43.2

16.0

14.2

12.1

Brown and dark brown sandy lean clay, moist

FILL

Very dark gray lean to fat clay, moist

LL = 48, PI = 30

LOCAL ALLUVIUM

Gray, trace sand, very moist after 6.5'

LL = 49, PI = 27

Moisture seepage near 9'

Brown sandy lean clay, trace gravel, moist

Clayey sand seam near 12.5'

Brown-gray after 14'

WISCONSINAN GLACIAL TILL

Dark gray after 17'

End of Boring

CL

CL-

CH

CL

SC

2.5 992.2

984.7

974.7

BORING LOG NO. 4 Project No.: 171419

Project: USDA Building 21 Renovation and Client: Stanley Consultants, Inc.

USDA Ames Laboratory, 1920 Dayton 100 Court Ave, Suite 300 Ames, Iowa Des Moines, IA 50309

Surface Elevation: 994.7' Date Drilled: 11/13/17 Drilling Method: 4" CFA Datum: GPS Survey Drilling Depth, ft.: 20 Page: 1 of

*The stratification lines represent the approximate boundary lines between material types: in-situ, the transition may be gradual.

Water Level Observation

ALLENDER BUTZKE ENGINEERS, INC.Time: at completion hrs. days Depth to Geotechnical | Environmental | Construction Q.C.water: 16 ft. ft. ft.

E le va tio n ft.

D ep th ft.

S am pl e

N o.

Ty pe

S P

T bp f

M oi st ur e C on te nt

D ry

D en si ty pc f

U nc on fin ed C om pr es si ve S tre ng th ps f Material Description*

G ra ph ic

Lo g

U S

C S

W at er L ev el

D ep th

E le va tio n

SSA

14.9

ST

18.4

SSA

20.2

ST

15.9

ST

13.3

ST

12.5

ST

12.7 10,900

ST

10.7

SSA

12.3

SSA

17.6

ST

16.4

ST

14.5

ST

15.8

ST

12.8

ST

11.8

SSA

13.0

SSA

26.2

ST

17.6

ST

15.9

ST

16.9

ST

13.3

ST

12.0

SSA

16.7

ST

26.1

ST

25.7

ST

43.2

ST

16.0

ST

14.2

ST

12.1

EL

EV

A

TI

O N

IN

F

EE

T

ELEV

A

TIO

N

IN

FEET

PROFILE OF BORINGS

Lean to Fat Clay Fill

Lean to Fat Clay Alluvium

Alluvial Sandy Lean To Fat Clay

Sandy Lean Clay

Crushed Rock With Fines

Clayey Sand

Lean Clay Fill

PROJECT NO.:

171419

DATE:

11/30/2017

PROJECT: USDA Building 21 Renovation and Addition USDA Ames Laboratory, 1920 Dayton Avenue Ames, Iowa

PLATE:

A-1

SCALE:

5 feet/in.

ALLENDER BUTZKE ENGINEERS, INC.

SB 1

SB 2

SB 3

SB 4

Approximate Soil Boring Location

ALLENDER BUTZKE ENGINEERS INC.

SB #

Urbandale, IA 50322 3660 - 109th Street

Site Plan

USDA Building 21 Addition 1920 Dayton Avenue

Ames, Iowa

PN 171419

Base Plan by Stanley Consultants with Google Aerial Overlay

0 50 100

Scale (feet)

Building 20

Building 21

AutoCAD SHX Text N

NOTES