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Geotechnical Engineering Report Kidder Heights Development

4502 South 60th Street

Omaha, Nebraska

September 10, 2015

Terracon Project No. 05155060

Prepared for:

Kidder Heights, LLC.

Omaha, Nebraska

Prepared by:

Terracon Consultants, Inc.

Omaha, Nebraska

Terracon Consultants, Inc. 15080 A Circle Omaha, Nebraska 68144

P [402] 330 2202 F [402] 330 7606 terracon.com

September 10, 2015

Kidder Heights, LLC.


Omaha, NE 68144

Attn: Mr. Rob Woodling

Re: Geotechnical Engineering Report

Kidder Heights Development


Omaha, Nebraska


Dear Mr. Woodling:

Terracon Consultants, Inc. (Terracon) has completed a subsurface exploration for the

referenced project. The accompanying geotechnical report presents the findings of the

subsurface exploration and provides recommendations for the design and construction of

footing foundations and grade-supported slabs for the proposed building. Exterior pavement

subgrade preparation, minimum pavement thickness, and general earthwork recommendations

are also included.

We appreciate the opportunity to work with you on this project and look forward to providing the

recommended construction observation/testing services. If you have any questions regarding

the attached report, or if we may be of further service, please contact us.

Sincerely,

Terracon Consultants, Inc.

Gopala K. Allam, E.I. Michael D. Ringler, P.E.

Project Geotechnical Engineer Sr. Project Geotechnical Engineer

GKA/MDR:gka/nlm

Distribution: Addressee (PDF)

Mr. Robert Engel, Robert W. Engel & Associates Architects (PDF)

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TABLE OF CONTENTS Page

EXECUTIVE SUMMARY ............................................................................................................. i

1.0 INTRODUCTION ............................................................................................................. 1

2.0 PROJECT INFORMATION ............................................................................................. 1

2.1 Project Description ............................................................................................... 1 2.2 Site Location and Description .............................................................................. 2

3.0 SUBSURFACE CONDITIONS ........................................................................................ 3

3.1 Mapped Soil Units ........................................................................................................... 3 3.2 Typical Profile ...................................................................................................... 3 3.3 Groundwater ........................................................................................................ 3

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION ........................................ 4

4.1 Geotechnical Considerations ............................................................................... 4 4.1.1 Low-Density Loess Soils........................................................................ 4 4.1.2 Proposed Grade Raise .......................................................................... 5

4.1.3 Soft Subgrade Conditions ...................................................................... 5 4.2 Site Preparation and Earthwork ........................................................................... 5

4.2.1 Site Stripping ......................................................................................... 5 4.2.2 Structural Fill Material Requirements ..................................................... 7 4.2.3 Structural Fill Compaction Requirements ............................................... 8 4.2.4 Utility Trench Backfill ............................................................................. 9 4.2.5 Construction Considerations .................................................................. 9 4.2.6 Exterior Grading .................................................................................. 10 4.2.7 Slope Maintenance .............................................................................. 10 4.2.8 Settlement ........................................................................................... 11

4.3 Spread Footing Foundations .............................................................................. 12 4.3.1 Design Recommendations ................................................................... 12 4.3.2 Construction Considerations ................................................................ 13 4.3.3 Seismic Considerations ....................................................................... 14

4.4 Floor Slab .......................................................................................................... 15 4.4.1 Design Recommendations ................................................................... 15 4.4.2 Construction Considerations ................................................................ 15

4.5 Lateral Earth Pressures ..................................................................................... 16 4.5.1 Design ................................................................................................. 16 4.5.2 Drainage Systems ............................................................................... 18

4.6 Exterior Pavements ............................................................................................ 18 4.6.1 Subgrades ........................................................................................... 18 4.6.2 Design and Thickness Recommendations ........................................... 19 4.6.3 Construction Considerations ................................................................ 20 4.6.4 Drainage and Maintenance Considerations ......................................... 20

4.7 Exterior Slabs .................................................................................................... 20 5.0 GENERAL COMMENTS ................................................................................................ 21

TABLE OF CONTENTS (CONTINUED)

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APPENDICES APPENDIX A – FIELD EXPLORATION

Exhibit A-1 Site Location Plan Exhibit A-2 Boring Location Plan (Aerial) Exhibit A-3 Boring Location Plan (Site Plan) Exhibit A-4 Field Exploration Description Exhibit A-5 to A-14 Boring Logs

APPENDIX B – LABORATORY TESTING

Exhibit B-1 Laboratory Testing

APPENDIX C – SUPPORTING DOCUMENTS Exhibit C-1 General Notes Exhibit C-2 Unified Soil Classification System Summary Exhibit C-3 References

Geotechnical Engineering Report Kidder Heights Development ■ Omaha, Nebraska September 10, 2015 ■ Terracon Project No. 05155060

Responsive ■ Resourceful ■ Reliable i 05155060R01.docx

EXECUTIVE SUMMARY

A geotechnical engineering report has been completed for the Kidder Heights Development

planned at 4502 South 60th Street in Omaha, Nebraska. The field exploration included ten

borings within the proposed building, garage, and parking lot areas. Laboratory tests were

performed on the samples recovered from the borings. Typed boring logs are included in

Appendix A.

Based on the information obtained from our subsurface exploration, the site can be developed for

the proposed project. The following geotechnical considerations were identified:

The borings encountered native loess soils for the entire depths explored. Groundwater

was encountered at a depth of about 13 feet in Boring B-5.

The soil borings encountered natural loess (wind-deposited) soils. In general, loess soils

are known to be collapse-susceptible upon wetting, particularly when the soils exist at

relatively low in situ dry densities. If encountered at footing bearing level, a localized

overexcavation and backfill procedure is recommended beneath the footings. Support of

the footings on suitable native soils or new fill extending down to suitable native clay

appears feasible.

Pavements and grade-supported floor slabs can be supported on a layer of low plasticity

cohesive fill formed by reworked and recompacted on-site soils. In addition, a granular

capillary moisture break is recommended immediately below grade-supported floor slabs.

The on-site soils appear suitable for reuse as low-plasticity cohesive fill, if free of organic

matter and debris. Moisture conditioning will be required for the on-site soils.

Several feet of grade-raise fill is planned in the southern portion of the building area.

The soils encountered below 13 feet in Boring B-5 near the east end of the south wing

of the building are soft to medium stiff in consistency. The proposed fill load, and

subsequent foundation and floor loading, will cause stress increases in the native

soils, resulting in several inches of settlement. We recommend pre-loading/surcharge the

south building wing to induce the expected settlement prior to foundation installation. A

time delay is also recommended between fill placement and paving.

In the south and south western portion of the building, the native clays soils at or close

below the ground surface could be soft and wet. Heavy construction equipment should not

be allowed on soft and wet clays, and an initial lift of crushed stone may be necessary.

TABLE OF CONTENTS (CONTINUED)

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Close monitoring of the construction operations discussed herein will be critical in

achieving the design subgrade and foundation support. We therefore recommend

Terracon be retained to monitor this portion of the work.

This summary should be used in conjunction with the entire report for design purposes. It should

be recognized that details were not included or fully developed in this section, and the report must

be read in its entirety for a comprehensive understanding of the items contained herein. The

section titled GENERAL COMMENTS should be read for an understanding of the report

limitations.

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GEOTECHNICAL ENGINEERING REPORT

KIDDER HEIGHTS DEVELOPMENT

4052 SOUTH 60TH STREET

OMAHA, NEBRASKA


September 10, 2015

1.0 INTRODUCTION

This report presents the results of our subsurface exploration for the Kidder Heights Development

planned at 4502 South 60th Street in Omaha, Nebraska. The field exploration included ten

borings to depths of approximately 5 to 25 feet below the existing ground surface within the

proposed building, garage, and parking lot areas. The individual boring logs are included in

Appendix A. The boring locations are shown on the Boring Location Plans, also included in

Appendix A.

Our work was completed in general accordance with our proposal agreement no. P05150410

dated May 7, 2015.

The purpose of these services is to provide information and geotechnical engineering

recommendations relative to:

soil conditions footing foundation design and construction

groundwater conditions floor slab design and construction

site preparation and earthwork pavement subgrade preparation

lateral earth pressures and

drainage, cantilever walls

minimum pavement thicknesses

2.0 PROJECT INFORMATION

2.1 Project Description

Item Description

Boring and Site layout Boring Location Plan, Exhibit A-2 and A-3 in Appendix A.

Structures The project will include a 75 unit, three-story building. Garages are

planned along the north property line.


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Item Description

Building construction

Wood framed with a brick veneer. Support is anticipated to be

provided by a conventional shallow footing foundation. Floor slabs

expected to be supported on-grade.

Finished floor elevation

(FFE) 1050 feet.

Maximum loads (assumed) Columns: 50 Kips Walls: 2 to 3 Kips/lf Slab: 100 psf

Site Development

L-shaped parking enters from 60th Street. Garage buildings are

planned along the north edge of the property. Two detention ponds

are planned west of the building.

Grading

Based on the review of grading plan, the majority of the building is

formed in fill. About 1 to 16 feet of fill is anticipated in the southern

wing of the building. Northern portion of the building will be formed

in cut; about 2½ to 11½ feet of cut is planned in the northern wing

of the building. Garage buildings will be formed in cut, with about 7

to 17 feet of cut planned.

Cut and fill slopes 3H:1V or flatter

Free-standing retaining walls

Several retaining walls planned. Aside from providing lateral earth

pressure and drainage recommendations for cantilever walls,

addressing retaining walls is not part of scope of services.

Below grade areas None.

2.2 Site Location and Description

Item Description

Location

4502 South 60th Street, Omaha, Nebraska. Approximate Latitude

41° 12.87' N / Longitude 96° 0.33' W. Refer to Site Location Plan,

Exhibit A-1, Appendix A.

Current ground cover

Approximately 2/3-thirds of site consists of tree canopy and grass-

covered areas. An existing farmstead and several buildings are also

present in the central portion of the site.

Existing topography

Review of the topographic plan provided to Terracon indicates the

site slopes down to the south with about 50 feet of grade change

across the site.

Surface conditions

Our field exploration was delayed because of soft soil conditions at

the ground surface, particularly in the south and southwest areas of

the site.

Should any of the above information or assumptions be inconsistent with the planned

construction or site development, please let us know so we may make any necessary

modifications to this report.



3.0 SUBSURFACE CONDITIONS

3.1 Mapped Soil Units

Surface soils at the project site were mapped as part of the effort to develop the Douglas County

NRCS-USDA Soil Survey. According to this document, the Monona series is mapped at the site.

The Monona series consists of very deep, well drained soils formed in loess. These soils have

low to moderate shrink-swell potential and high frost action potential. The seasonal high water

level in these series is noted as greater than about 6 feet below native grade.

The soil profile may have been altered by grading associated with urban construction and

development.

More information is presented in the Soil Survey of Douglas and Sarpy Counties, Nebraska.

3.2 Typical Profile

Based on the results of the borings, we anticipate the subsurface conditions on the project site

can be generalized as follows:

Layer Approximate Depth

to Bottom of Stratum Material Encountered Consistency/Density

Surface: N/A Grass, shallow root zone N/A

Stratum 1

(Loess)

5 to 25-foot

termination depth of all

borings

Lean Clay, Lean to Fat Clay

Stiff to Very Stiff

Medium Stiff to Soft below 13

feet in Boring B-5

Conditions encountered at each boring location are indicated on the individual boring logs.

Additional information is presented on the boring logs in Appendix A. Stratification boundaries on

the boring logs represent the approximate location of changes in soil types; in-situ, the transition

between materials may be gradual.

Variations may occur between soil borings or across the site. Previous grading and construction

may have created additional variations.

3.3 Groundwater

The boreholes were observed while drilling for the presence and level of groundwater. The water

levels observed are noted on the attached boring logs, and are summarized below.



Boring Number Depth to groundwater while drilling, ft.

B-5 13

Remaining borings Not encountered

A relatively long period of time is necessary for a groundwater level to develop and stabilize in a

borehole. Longer term monitoring in cased holes or piezometers would be required for a more

accurate evaluation of the groundwater conditions.

Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff,

river levels and other factors not evident at the time the borings were performed. Therefore,

groundwater levels during construction or at other times in the life of the structure may be higher

or lower than the levels indicated on the boring logs. It is also our experience that perched

water can develop overlying compacted clay fill and overlying dense native clay. The possibility

of groundwater level fluctuations and development of perched water conditions should be

considered when developing the design and construction plans for the project.

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

4.1 Geotechnical Considerations

4.1.1 Low-Density Loess Soils

The soil borings encountered natural loess (wind-deposited) soils. In general, loess soils are

known to be collapse-susceptible upon wetting, particularly when the soils exist at relatively low

in situ dry densities (e.g., less than about 85 pcf). Our borings did not encounter soils with

densities lower than 85 pcf but several samples had densities lower than 90 pcf. Although the

low-density soils have sufficient strength to support the expected foundation loads in their

currently dry condition, low-density loess soils are susceptible to strength loss and collapse upon

wetting, and present a risk of foundation settlement should they become wetted at any time during

the life of the structure. Should dry, collapse-susceptible loess be encountered at footing-bearing

elevation during construction, supporting the footing on at least 2 feet of reworked and

recompacted soil would be appropriate.

Although moisture-sensitive soils may be present below the densified zone, the relatively low

permeability of the densified layer will help reduce the rate of vertical infiltration of surface water

into the underlying moisture-sensitive soils. Replacement of the overexcavated soils as

compacted fill should be performed in accordance with the recommendations outlined in this

report. Even with the recommended soil improvements, additional recommendations are provided

concerning site grading and landscaping to help reduce the potential for surface water infiltration.



4.1.2 Proposed Grade Raise

Based on the grading plan provided to us, we anticipate grade raise of about 3 to 16 feet will be

required in the southern building wing. The soils encountered below 13 feet in Boring B-5 are

soft to medium stiff in consistency. The proposed fill load, and subsequent foundation and

floor loading, will cause stress increases in the native soils, resulting in estimated settlement of

about 3 inches. We recommend pre-loading/surcharge the southern wing building to induce the

expected settlement prior to foundation installation. Similarly, we recommend the fill required for

the parking lot east of the building be placed at least 6 to 8 weeks prior to paving. The preloading

process should be monitored with settlement plates, and the construction schedule will need to

accommodate the time interval for preloading. Additional discussion and recommendations are

presented in subsection 4.2.8 Settlement.

4.1.3 Soft Subgrade Conditions

Terracon had difficulty accessing the site during field exploration with a truck-mounted drill rig

due to steep terrain and soft ground conditions. Several unsuccessful trips were made to the

site.

The surficial soils were soft and wet along the south leg of the building. These soils will be at

subgrade level in the southwest portion of the building, and fill is planned over these soils in the

southeast portion of the building. These materials may be unstable under construction

equipment loads. Scarification and drying or subgrade stabilization will be required prior to

placing fill if these soils are wet and soft. Subgrade stabilization could contain installation of a

granular working base.

4.2 Site Preparation and Earthwork

4.2.1 Site Stripping

Stripping of all existing vegetation, organic topsoil, and other materials unsuitable for re-use as

engineered fill should be performed within all cut, fill, paving, and building areas. A typical

stripping depth of about 6 to 9 inches is expected to be adequate in most areas. However, areas

of both deeper and shallower stripping could be encountered. A Terracon geotechnical

representative should help evaluate actual stripping depths at the time of construction. We

recommend that site stripping and subgrade preparation procedures extend at least 5 feet

beyond the building perimeter, and at least 2 feet beyond the edges of the proposed

pavements.

Tree and shrub root systems and any desiccated soils should be thoroughly removed from the

building and pavement areas, and areas to receive fill. An effort should be made to locate

records, plats or photographs indicating the past location of trees or other large vegetation at the

site. In addition, some of the natural soils may have been desiccated by the tree roots. Desiccated

clays present a significant risk of heave if left in-place below foundations or floor slabs. Therefore,



any soils desiccated by trees or shrub roots should be thoroughly removed and replaced with low-

plasticity cohesive fill.

Existing foundations, floor slabs, basement walls, cisterns, utilities, and other farmstead

structures should be removed. This process should include removal of existing fill and any

organic topsoil buried by the existing fill. The actual removal depths and lateral extents should

be evaluated by a Terracon representative during construction.

We recommend floor slabs and pavements be underlain by at least 8 inches of low plasticity

cohesive fill formed by reworking and recompacting on-site soils. We recommend pavement

areas be cut and filled to subgrade level during mass grading. Immediately prior to paving, we

recommend the pavement subgrade soils be scarified and recompacted as discussed in

subsection 4.2.3 Structural Fill Compaction Requirements.

In the south and south western portion of the building, the native clays soils at or close below the

ground surface could be soft and wet. Heavy construction equipment should not be allowed on

soft and wet clays, and an initial lift of crushed stone may be necessary. If areas of rutting or other

disturbance develop, the disturbed material should be recompacted or removed and replaced.

Fill placed on a slope steeper than 5H:1V (horizontal to vertical) should be benched into the

slope. A maximum riser height on the order of 2 feet, separated by horizontal steps that are

wide enough to accommodate compaction equipment, is recommended.

Proofrolling is recommended after stripping in areas to receive fill. Proofrolling aids in providing

a firm base for compaction of fill and delineating soft, or disturbed areas that may exist below

subgrade level. Unsuitable areas observed at this time should be improved by scarification and

recompaction or by undercutting and replacement with structural fill. Initially, proof-rolling may

be accomplished with a third- to half-loaded, tandem-axle, dump truck with a gross weight of 15

tons or other equipment providing an equivalent subgrade loading. If the subgrade holds up well

under the initial loading, proofrolling may be attempted with a fully-loaded, tandem-axle, dump

truck with a minimum gross weight of 25 tons or other equipment providing an equivalent

subgrade loading.

The native soils in some of the borings have high moisture contents and are susceptible to

disturbance from construction activity and surface water / seepage. Even where the hand

penetrometer tests indicate these materials may be stiff, we anticipate they will degrade rapidly

under loading from construction activity. The use of either remote equipment (e.g,. backhoes) or

construction equipment with relatively light contact pressures is recommended; heavy

construction traffic should not be allowed. Construction operations in these areas should be

carefully monitored, and restricted if subgrade disturbance becomes apparent. Disturbed soils

should be removed and replaced.



Terracon should be retained to monitor stripping, subgrade stability, foundation and existing fill

removal, utility abandonment, site excavation, removal of unsuitable materials, and proofrolling.

Terracon can assist in low-strength native soils that should be undercut and removed, as well as

identifying additional corrective measures for conditions that may become apparent during

construction.

4.2.2 Structural Fill Material Requirements

Structural fill should meet the following material property requirements:

Fill Type 1 USCS Classification Acceptable Location for Placement

Low-plasticity,

cohesive soil

CL

(LL<45 and 10<PI<20) 2

All locations and elevations.

Granular 3

SP, SW, GW Directly below slabs-on-grade.

Drainage Fill 5 SP, SW, GW Free-draining granular fill behind retaining walls.

“Bridge lift” granular 6 SP, SW, GW Stabilizing layer at the soft subgrade locations.

On-Site Soil 4

CL Suitable if meeting the requirements of “Low

Plasticity Cohesive” above.

1. Structural fill should consist of low or moderate plasticity cohesive soils or approved granular materials

that are free of organic matter, debris, and contamination. Frozen material should not be used, and fill

should not be placed on a frozen subgrade. Each proposed fill material type should be sampled and

evaluated by the geotechnical engineer prior to its delivery and/or use.

2. LL = Liquid Limit, PI = Plasticity Index.

3. A material similar to NDOR Crushed Rock for Base Course, with 6% or less fines (material passing the

#200 sieve). Terracon is available to review gradations of proposed materials.

4. Sorting of on-site soils containing debris, organics, etc., will be necessary. Delineation of unsuitable on-

site soils should be performed in the field by a Terracon representative. Moisture conditioning of the on-

site soils is anticipated to be necessary to facilitate compaction.

5. Well-graded, free-draining granular material. A general gradation should be 100% passing the 1½-

inch sieve, about 40 percent passing the No. 10 sieve, and less than 6 percent fines. NDOR 47B

Fine Aggregate For Concrete or approved alternate.

6. Imported. Well-graded, crushed stone or crushed concrete, containing 100 percent passing the 3-inch

sieve and less than 10 percent fines. Crushed concrete can be used but is subject to degradation

under repetitive traffic loads, and so should be used with caution. Terracon can review proposed

materials.

Terracon should be retained to evaluate proposed fill materials, including performing laboratory

tests to evaluate compliance with the project specifications. We can also review test results

provided by the contractor.



4.2.3 Structural Fill Compaction Requirements

Item Description

Fill Lift Thickness 1

8-inches or less in loose thickness

Compaction Requirements 2, 3, 5

Upper 8 inches of pavement

subgrade

Below footings and all other

locations

98% of the materials maximum standard Proctor dry

density (ASTM D 698)

95% of the materials maximum standard Proctor dry

density (ASTM D 698).

Moisture Content - Cohesive Soil

Within the range of -2 to +3 percent of the optimum

moisture content value as determined by the

standard Proctor test at the time of placement and

compaction.

Moisture Content - Granular Material 4 Workable moisture levels

1. Thinner lifts may be required in confined areas or within excavations. Or when hand-operated

compaction equipment is used.

2. We recommend engineered fill be tested for moisture content and compaction during

placement. Should the results of the in-place density tests indicate the specified moisture or

compaction limits have not been met, the area represented by the test should be reworked and

retested as required until the specified moisture and compaction requirements are achieved.

3. Consideration can be given to compacting all fill below pavements to 95% during mass

grading. Immediately prior to paving, we recommend that the subgrade below exterior

pavements be rough-graded as needed, and then scarified and recompacted. We recommend

this process include scarifying the subgrade to a depth of about 9 inches, moisture conditioning

the scarified soil to within -2 to +3 percent of the material’s optimum, and compacting the

scarified soil to at least 98%. Scarified soils which cannot be recompacted to this degree

should be undercut and replaced with stable material.

4. Specifically, moisture levels should be maintained low enough to allow for satisfactory

compaction to be achieved without the cohesionless fill material pumping when proofrolled or

containing excess water (ponding).

5. Where a granular layer fill is placed over a subgrade composed of wet or soft clay, care should be

taken not to overcompact the initial lift of fill. Overcompaction can cause subgrade disturbance

and loss of strength of the underlying subgrade. In these areas, we recommend that the

compaction be accomplished with 2 or 3 mutually perpendicular passes of each thin lift with light-

eight vibratory compaction equipment. Instead of a strict compaction requirement, consideration

should be given to using visual evaluation of material stability using factors such as surface

stability and aggregate interlock when evaluating compaction and performance of the granular

material.

Terracon should be retained to monitor fill placement and to perform field density tests as each lift

of fill is place in order to evaluate compliance with the design requirements. We should be retained

to observe and test floor slab and pavement subgrades immediately prior to paving.



4.2.4 Utility Trench Backfill

All trench excavations should be made with sufficient working space to permit construction

including backfill placement and compaction. If utility trenches are backfilled with relatively clean

granular material, they should be capped with at least 18 inches of cohesive fill in non-pavement

areas to reduce the infiltration and conveyance of surface water through the trench backfill. We

also recommend that all utility trenches be plugged with a clay core at locations where they enter

under the new building to prevent the utility trench from being a route for water to get into the new

building structure.

4.2.5 Construction Considerations

Any areas of standing surface water should be drained as far in advance of construction as

possible.

The native clays encountered in the borings will be sensitive to disturbance from construction

activity and water seepage. If precipitation occurs immediately prior to or during construction, the

near-surface clay soils could increase in moisture content and become more susceptible to

disturbance. Construction activity should be monitored, and should be curtailed if the construction

activity is causing subgrade disturbance. A Terracon representative can help with monitoring and

developing recommendations to avoid subgrade disturbance.

Surface water should not be allowed to pond on the site and soak into the soil during construction.

Construction staging should provide drainage of surface water and precipitation away from the

building and pavement areas. Any water that collects over or adjacent to construction areas

should be promptly removed, along with any softened or disturbed soils. Surface water control in

the form of sloping surfaces, drainage ditches and trenches, and sump pits and pumps will be

important to avoid ponding and associated delays due to precipitation and seepage.

Upon completion of filling and grading, care should be taken to maintain the subgrade moisture

content prior to construction of floor slabs and pavements. Construction traffic over the

completed subgrade should be avoided to the extent practical. The site should also be graded

to prevent ponding of surface water on the prepared subgrades or in excavations. If the

subgrade should become frozen, desiccated, saturated, or disturbed, the affected material

should be removed or these materials should be scarified, moisture conditioned, and

recompacted prior to floor slab and pavement construction.

As a minimum, all temporary excavations should be sloped or braced as required by

Occupational Safety and Health Administration (OSHA) regulations to provide stability and safe

working conditions. Temporary excavations will probably be required during grading operations.

The grading contractor, by his contract, is usually responsible for designing and constructing

stable, temporary excavations and should shore, slope or bench the sides of the excavations as

required, to maintain stability of both the excavation sides and bottom. All excavations should



comply with applicable local, state and federal safety regulations, including the current OSHA

Excavation and Trench Safety Standards.

4.2.6 Exterior Grading

Poor site drainage and ponding of surface water can increase the potential for frost heave or

settlement. Excessive moisture can reduce the soil's bearing capacity and contribute to slab and

pavement settlement and cracking.

Finished grading slopes should promote drainage away from the building and pavement areas to

help prevent post-construction wetting of the bearing soils. We recommend final grades for seeded

and landscaped areas be sloped at least 5 percent within 10 feet around the buildings to direct

surface water well away from the buildings. We recommend cohesive backfill be placed in utility

trenches and adjacent to building foundations and curbs, and this fill be compacted to at least 95

percent of standard Proctor maximum dry density to help prevent surface water infiltration. Roof

drains should be extended to discharge on pavements or in lawn areas more than 5 feet from the

buildings. Pavements or sidewalks installed adjacent to the building should slope away from the

building at a grade of 2% or more.

Overwatering of grass or landscaping vegetation is a significant source of water, and should be

avoided near the buildings and pavements. Sprinkler heads should be adjusted to miss the

exterior building wall and pavements. Automated watering systems should be programmed to not

run after natural rain events, and to not overwater. Any utility leaks should be promptly repaired.

Lining the bottom of irrigated planter areas along the building with an impermeable moisture

barrier, and installing tile lines leading to gravity outlets or sump pits and pumps, would also help to

control surface water that infiltrates into these features.

4.2.7 Slope Maintenance

Large cut and fill slopes are planned. A detailed stability evaluation of the cut and fill slopes is

beyond our current scope, and would require additional field exploration and laboratory testing.

We understand the cut slopes will generally have inclinations of 3H:1V or flatter. It is our

experience that slopes in the dry loess soils flatter than about 3H:1V would not expected to

experience deep-seated slope failure. Slopes of 3H:1V are anticipated to be stable in the native

loess soils where seasonal groundwater seepage does not exit the proposed slope and surface

water infiltration is limited above the slope by including proper drainage.

The planned cuts slopes are expected to encounter native loess soils. Flowing water and soft,

saturated soils are not expected to be encountered within the proposed depths of cut in the loess

soils. However, seepage can occur seasonally and after periods of heavy or prolonged rainfall.

The seepage could cause minor, long-term maintenance concerns with the slope, such as erosion

and localized slumps or soft areas. These surface developments typically do not jeopardize the



deep seated stability of the slope, but could mar the surface of the slope and, if allowed to

progress, could eventually affect the property behind the top of the cut slope.

Subsurface drains can be used to intercept the seepage from seasonally wet areas before it can

exit the cut face and cause surface movements. Cut slope conditions should be observed by

Terracon personnel during construction. The need for subsurface drains should be determined

based on observations after excavation of the slope. We recommend that the project budget

include contingency funds to install these drains.

The clay soils at this site have a high silt content. As a result, slopes exposing or formed of this

material are highly susceptible to surface erosion, sediment transport and sloughing, and will be

difficult to maintain. Surface runoff should be diverted away from the slopes. A series of benches

can be installed to break the slope into distinct units, and to help control surface water and any

areas of localized instability. Erosion protection will be required. If a vegetative cover is planned,

temporary erosion protection may be required until the vegetation can be established.

4.2.8 Settlement

4.2.8.1 Settlement Discussion

Based on the grading plan provided to us, we anticipate grade raise of about 3 to 16 feet will be

required in the southern wing of the building area. The soils encountered below 13 feet in

Boring B-5 are soft to medium stiff in consistency. The proposed fill load, and subsequent

foundation and floor loading, will cause stress increases in the native soils, resulting in

estimated settlement of up to about 3 inches. We recommend pre-loading/surcharge in the

southern wing of the building area to induce the expected settlement prior to foundation

installation. The preloading process should be monitored with settlement plates, and the

construction schedule will need to accommodate the time interval for preloading. Similarly, we

recommend the fill required for the parking lot east of the building be placed at least 6 to 8 weeks

prior to paving.

4.2.8.2 Preload Fill and Surcharge Fill Placement

To preload, all permanent structural fill should be placed up to finished subgrade elevation in

the planned building and to a distance extending at least 20 feet beyond the building

perimeter. The permanent fill should be placed and compacted according to the

recommendations presented in subsection 4.2 Site Preparation and Earthwork.

Placement of additional surcharge fill is recommended to compensate for building and floor

loads. We recommend the surcharge fill extend to the 3 feet height in the building area and at

least 10 feet beyond the building perimeter. The surcharge fill can be placed in lifts 12

inches thick and tracked into place with loaded scrapers or dump trucks. A minimum

compaction criterion is not required, but we recommend the as placed surcharge fill have a

minimum in situ wet unit weight of 100 pcf. The top of the surcharge fill should be sloped to



drain to reduce moisture infiltration. The edges of the surcharge should be sloped at 3H:1V

or flatter within the building footprint, but may be steeper where extended beyond the building

footprint.

4.2.8.3 Settlement Monitoring

After placement of the permanent fill and prior to placement of surcharge fill, survey

monuments should be installed for settlement monitoring. We recommend a minimum of two

monuments. The monuments should consist of 2-foot square steel plates firmly embedded on the

permanent fill, with metal riser pipe coupled to the top of the settlement plate and extending above

the preload fill height. Plastic pipe should be installed around the steel riser pipes. Care should

be taken not to disturb the monuments during preload fill and surcharge fill placement. A

monument which is damaged or disturbed should be repaired or replaced immediately.

We recommend surveying the elevations of the settlement monuments to the nearest 100th

of a foot, and the elevation of the top of the adjacent preload fill and surcharge fill to the

nearest 10th of a foot, according to the following schedule:

Time Period Monitoring Schedule

At Time of Monument Seating Initial Readings

During Preload Fill and Surcharge Fill Placement Daily

For two weeks following fill placement Three times per week

Between Two and Four Weeks Following Fill Placement Two times per week

More Than Four Weeks Following Fill Placement, if required Once per week

The monitoring data should be submitted to Terracon for analysis and evaluation of when

construction may proceed. A settlement period of about 6 to 8 weeks is estimated to achieve

adequate consolidation of the compressible layers. This is only an estimate based on our

experience with projects of this type, the soil conditions observed, and the test results. Other

factors affecting the effective drainage path and permeability of the soils may reduce the time

for the settlement to occur. We anticipate at least 4 weeks of settlement data will be required

after surcharge fill placement, before we can begin evaluation of eventual total settlements and

refinement of our time frame estimates.

4.3 Spread Footing Foundations

4.3.1 Design Recommendations

Based on the soil information from borings, low density, dry, collapse-susceptible loess may be

encountered at footing-bearing elevation during construction at isolated locations. Where

encountered, or supporting the footing on at least 2 feet of reworked and recompacted soil is

recommended.



In our opinion, the proposed buildings can be supported by a shallow, spread footing foundation

system bearing on suitable native soils, newly placed engineered fill that extends to suitable

native soils or on 2 feet of newly placed engineered fill overlying low density loess soil. Design

recommendations for shallow foundations for the proposed structure are presented in the

following table.

Description Column Wall

Net allowable bearing pressure (soil) 1

2,000 psf 2,000 psf

Minimum dimensions 30 inches 18 inches

Minimum embedment below finished grade 2 42 inches 42 inches

Estimated total settlement 3 <1 inch <1 inch

Estimated differential settlement 3 <2/3 inch between columns <2/3 inch over 40 feet

1. The recommended net allowable bearing pressure is the pressure in excess of the minimum

surrounding overburden pressure at the footing base elevation. Assumes any disturbed or soft

soils, if encountered, will be undercut and replaced with engineered fill. Where encountered, low

density loess to be undercut and replaced to 2 feet below footings.

2. For frost protection and to reduce the effects of seasonal moisture variations in the subgrade soils.

For perimeter footings and footings in unheated areas. If construction extends into freezing

weather, we recommend that either all footings extend to frost depth (as measured from adjacent

grade at the time of construction) or that the foundations be protected from the elements by straw,

frost blankets, or similar means.

3. The foundation settlement will depend upon the variations within the subsurface soil profile, the

structural loading conditions, the embedment depth of the footings, the thickness of compacted fill,

and the quality of the earthwork operations. The above settlement estimates have assumed that

the maximum footing size is 5 feet for column footings, 2 feet for continuous footings, and relatively

uniform loading.


As discussed previously, the boring encountered native loess soils. When encountered, we

recommend the low-density soils be removed to 2 feet below footing bearing level, widened as

depicted below, and backfilled with low-plasticity cohesive fill, placed and compacted as

recommended in subsection 4.2 Site Preparation and Earthwork.

Terracon should be retained to observe and test the bearing materials exposed in all foundation

excavations. If unsuitable soils are encountered in footing excavations, the excavations should

be extended deeper to suitable materials. The footings could bear directly on these materials at

the lower level or on lean concrete backfill placed in the excavations. The footings could also

bear on approved, properly compacted backfill extending down to the suitable materials.

Overexcavation for compacted backfill placement below footings should extend laterally at least

8 inches beyond the edges of the footings for each foot of overexcavation depth below footing

base elevation. The overexcavation should then be backfilled up to the footing base elevation



with engineered fill placed and compacted in accordance with recommendations provided in

subsection 4.2 Site Preparation and Earthwork. Schematics of these alternatives are

presented in the adjacent figure.

The soils on this site are susceptible to disturbance from construction activity, especially if

exposed to water. Care should be taken during excavation and construction of footings to avoid

disturbing the bearing soils. The base of all foundation excavations should be free of water and

loose material prior to placement of concrete. Concrete should be placed within a few hours after

excavating to reduce disturbance of the bearing materials. If the materials at bearing level

become excessively dry, disturbed or saturated, the affected material should be removed prior to

placing concrete. A 2- to 3-inch lean concrete “mud mat” could be placed in the base of the

foundation excavations to reduce the potential for disturbance of bearing soils and provide a

stable working surface.

4.3.3 Seismic Considerations

Based upon the results of the soil borings, we estimate the project site as “Site Class D”

according to the 2006 International Building Code (IBC). This site class assumes the soils

encountered at the bottom of the borings (except B-5) continue to a depth of 100 feet. A more

detailed and accurate Site Class evaluation can be achieved by performing a deeper soil boring,

by performing a cone sounding with shear wave measurements, or using the SeisOpt®ReMi™

method to develop the full depth shear wave profile.

In our opinion, the following spectral response accelerations are applicable to this site location

based on the applicable response maps are: Ss = 0.126g and S1 = 0.042g. The City of Omaha

has adopted the 2006 IBC. Upon adoption of the 2006 IBC by the City of Omaha, amendments

were installed, including the following spectral response accelerations: Ss = 0.125g and S1 =

0.041g. These values are based on a 2% probability of exceedance in 50 years, and were

obtained from the Interpolated Probabilistic Ground Motion for the continuous 48 states by

Latitude and Longitude, USGS 2002 Data Base. The Ss and S1 values were developed for a



Site Class B, and are used in conjunction with coefficients based on site class to determine the

maximum acceleration, Sm1 and Sms.

4.4 Floor Slab

4.4.1 Design Recommendations

Item Description

Floor slab support 1

Aggregate base (see below) underlain by at least 8

inches of low plasticity cohesive fill formed by reworking

and recompacting on-site materials prepared according

to Section 4.2 Site Preparation and Earthwork.

Modulus of subgrade reaction 100 pounds per square inch per in (psi/in) for point

loading conditions

Aggregate base course/capillary break 2 4 inches of free draining granular material

1. Floor slabs should be structurally independent of any building footings or walls to reduce the

possibility of floor slab cracking caused by differential movements between the slab and

foundation.

2. The floor slab design should include a capillary break, comprised of compacted, granular material,

as described in Section 4.2.2 Structural Fill Material Requirements.

Slabs-on-grade should be isolated from structures and utilities to allow for their independent

movement. Joints should be constructed at regular intervals as recommended by the American

Concrete Institute (ACI) to help control the location of any cracking. Keyed and doweled joints

should be considered. The owner should be made aware that differential movement between

the slabs and foundations could occur.

The use of a vapor retarder should be considered beneath concrete slabs on grade that will be

covered with wood, tile, carpet or other moisture sensitive or impervious coverings, or when the

slab will support equipment sensitive to moisture. When conditions warrant the use of a vapor

retarder, the slab designer should refer to ACI 302 and/or ACI 360 for procedures and cautions

regarding the use and placement of a vapor retarder.


On most project sites, the floor slab subgrades are generally developed early in the construction

phase. However as construction proceeds, the subgrade may be disturbed due to utility

excavations, construction traffic, desiccation, rainfall, etc. As a result, the floor slab subgrade may

not be suitable for placement of base rock and concrete and corrective action will be required.

We recommend the floor slab subgrade be rough graded and then proofrolled with a loaded

tandem axle dump truck prior to fine grading and placement of base rock. Particular attention

should be paid to high traffic areas that were rutted and disturbed earlier and to areas where



backfilled trenches are located. Areas where unsuitable conditions are located should be repaired

by removing and replacing the affected material with properly compacted fill. All floor slab

subgrade areas should be moisture conditioned and properly compacted to the recommendations

in this report immediately prior to placement of the aggregate base course and concrete.

4.5 Lateral Earth Pressures

4.5.1 Design

The lateral earth pressure recommendations given in this section are applicable to the design of

rigid retaining walls subject to slight rotation, such as cantilever, or gravity type concrete walls.

These recommendations are not applicable to the design of modular block - geogrid reinforced

backfill walls (also termed MSE walls). Recommendations covering these types of wall systems

are beyond the scope of services for this assignment. However, we would be pleased to

develop a proposal for evaluation and design of such wall systems upon request.

Reinforced concrete walls with unbalanced backfill levels on opposite sides should be designed

for earth pressures at least equal to those indicated in the following table. Earth pressures will

be influenced by structural design of the walls, conditions of wall restraint, methods of

construction and/or compaction and the strength of the materials being restrained. Two wall

restraint conditions are shown. Active earth pressure is commonly used for design of

free-standing cantilever retaining walls and assumes wall movement. The "at-rest" condition

assumes no wall movement. The recommended design lateral earth pressures do not include a

factor of safety and do not provide for possible hydrostatic pressure on the walls.



Earth Pressure Coefficients

Earth Pressure

Conditions

Coefficient for

Backfill Type

Equivalent Fluid

Density (pcf)

Surcharge

Pressure, p1 (psf)

Earth Pressure,

p2 (psf)

Active (Ka) Granular - 0.33

Lean Clay - 0.42

40

50

(0.33)S

(0.42)S

(40)H

(50)H

At-Rest (Ko) Granular - 0.46

Lean Clay - 0.50

55

60

(0.46)S

(0.50)S

(55)H

(60)H

Passive (Kp) Granular - 3.0

Lean Clay - 2.4

360

290

---

---

---

---

Applicable conditions to the above include:

For active earth pressure, wall must rotate about base, with top lateral movements of

about 0.002 H to 0.004 H, where H is wall height

For passive earth pressure to develop, wall must move horizontally to mobilize

resistance

Uniform surcharge, where S is surcharge pressure

In-situ soil backfill weight a maximum of 120 pcf

Horizontal backfill, compacted between 95 and 98 percent of standard Proctor maximum

dry density

No hydrostatic pressure acting on wall

No loading from compaction equipment

No loading from nearby footings or slabs

No dynamic loading

Finished grade is horizontal both behind wall and at toe of wall

No safety factor included in soil parameters

Ignore passive pressure in frost zone

Backfill placed against structures should consist of granular soils or low plasticity cohesive soils.

For the granular values to be valid, the granular backfill must extend out from the base of the wall

at an angle of at least 45 and 60 degrees from vertical for the active/at-rest and passive cases,

respectively. To calculate the resistance to sliding, a value of 0.4 should be used as the ultimate

coefficient of friction between the footing and the underlying soil.

Footings and other loads located adjacent to walls may have a significant effect on lateral

pressures. Placement of footings in wall backfill should be avoided unless structural analyses

are performed to evaluate the resulting loads and effects on the wall. To avoid excessive lateral

wall loads, heavy compaction equipment should not be operated within a distance out from new

or existing walls equal to the height above the base of the wall.



4.5.2 Drainage Systems

A perforated rigid plastic or metal drain line should be installed behind the retaining walls to prevent

hydrostatic loading on the walls. The invert of a drain line around the retaining walls should be at

least 6 inches below the slab on the low side of the wall. The drain line should be sloped to provide

positive gravity drainage to a

sump or other suitable outlet.

The drain line should be

surrounded by free-draining

granular material graded to

prevent the intrusion of soil

fines into the granular

material or the intrusion of the

granular material into the

drain pipe perforations.

Alternatively, a coarse, clean,

free-draining granular

material could be used to

surround the pipe if this

material is encapsulated with

suitable filter fabric.

At least a 2-foot wide section of free-draining granular fill is recommended for backfill above the

drain line and adjacent to the wall and should extend up to within 2 feet of exterior grade. A

prefabricated drainage structure may be used above a drain line and the surrounding filter, in lieu

of free-draining granular fill. A prefabricated drainage structure is a plastic drainage core or mesh

which is covered with filter fabric to prevent soil intrusion, and is fastened to the wall prior to placing

backfill.

If this is not possible to install a drain along the base of the wall, then combined hydrostatic and

lateral earth pressures should be calculated using the following values:

Active Condition 1 At-Rest Condition

1

Clay Backfill 90 pcf 100 pcf

Granular Backfill 85 pcf 95 pcf

1. These pressures do not include the influence of surcharge,

equipment, or floor loading, which should be added.

4.6 Exterior Pavements

4.6.1 Subgrades

The pavements should be underlain by at least 8 inches of reworked and recompacted low

plasticity cohesive fill prepared in accordance with the recommendations presented in subsection



4.2 Site Preparation and Earthwork. Typical construction in the Eastern Nebraska area is not

to place a granular base below pavements for this type of facility. Rather, the pavements are

supported directly on the cohesive subgrade soils. If the project design results in a granular base

being installed below pavements, Terracon should be retained to provide additional

recommendations. For example, subdrains are recommended in conjunction with a granular base

to prevent water from ponding in the granular base.

4.6.2 Design and Thickness Recommendations

We recommend the following pavement sections:

Standard Duty Pavements: For parking areas subjected to low volumes of automobile

traffic, a full-depth ACC section having a total thickness of at least 6 inches, or a PCC

pavement section having a thickness of at least 5 inches, is recommended.

Heavy-Duty Pavements: Entry drives and truck driveways require increased pavement

thicknesses. A minimum 7-inch thick ACC section, or a minimum 6-inch thick PCC

section, is recommended in these areas.

Truck Pads: A minimum 7-inch thick PCC section is recommended for aprons in truck

loading docks, delivery truck parking areas, and refuse pick-up areas. Such areas

should have a concrete section wide enough to accommodate the vehicles that would use

it.

Terracon has observed dishing in some parking lots surfaced with ACC. Dishing is usually

observed in frequently-used parking stalls (such as near the front of the building), and occurs

under the wheel footprint in these stalls. The use of higher grade asphaltic cement such as

PG70-28, or surfacing these areas with PCC, is recommended. The dishing is exacerbated by

factors such as irrigated islands or planter areas, sheet surface drainage to the front of the

building, and placing the ACC directly on a compacted clay subgrade. The use of lower grade

asphalt cement, such as PG64-22 is relatively common in this area and may be considered, but

would provide lower reliability against rutting and creeping during warm weather.

Minimum surface course thicknesses of 2 inches in automobile areas and 3 inches in driveways

are recommended for asphaltic cement concrete pavement sections. An ACC base course

thickness of 4 inches is recommended.

We recommend that ACC and PCC pavement specifications reference Sections 400 and 500,

respectively, of the City of Omaha Standard Specifications for Public Works Construction, 2003

Edition. We recommend a surface mix type CMR for ACC pavements and mix type L65 for

PCC pavements.



A formal pavement design has not been completed for this project. The above recommended

pavement sections are typical minimum values and thicker pavement sections could be used to

reduce maintenance and extend the expected service life of the pavements. Periodic maintenance

will also extend the service life of the pavements and should include patching and repair of

deteriorated areas, crack sealing, and surface sealing. We recommend that a California Bearing

Ratio (CBR) test and a formal pavement design be completed if unusually high vehicle loads or

frequencies are anticipated.


Construction scheduling often involves grading and paving by separate contractors and can

involve a time lapse between the end of grading operations and the commencement of paving.

Disturbance, desiccation or wetting of the subgrade soils between grading and paving can result

in deterioration of the previously completed subgrade. A non-uniform subgrade can result in

poor pavement performance and local failures relatively soon after pavements are constructed.

We recommend the moisture content and density of the subgrade be evaluated within two days

prior to commencement of actual paving operations. A proof roll using heavy equipment similar

to that required for pavement construction is also recommended to verify subgrade stability for

pavement construction. Scarification and recompaction may also be required.

Areas not in compliance with the required ranges of moisture or density should be moisture

conditioned and recompacted. If significant precipitation occurs after the evaluation or if the

surface becomes disturbed, the subgrade condition should be reviewed by Terracon personnel

immediately prior to paving.

4.6.4 Drainage and Maintenance Considerations

Preventing subgrade saturation is an important factor in maintaining the subgrade strength. Water

allowed to pond on or next to pavements could saturate the subgrade and cause premature

pavement deterioration. Positive surface drainage should be provided away from the edges of

paved areas, and all pavements should be sloped to provide rapid surface drainage. Pavements

should drain toward the edges rather than the center, and perimeter subsurface drains should be

installed next to irrigated planters or other areas where surface water could pond.

4.7 Exterior Slabs

The clayey soils on this site are considered highly frost susceptible. Grade-supported exterior

slabs should be expected to heave. The amount of heave may be reduced by providing surface

drainage away from the building and slabs and toward the site storm drainage system. Structural

stoops are recommended adjacent to exterior doors and other movement-sensitive exterior slabs.

Consideration should be made to installing drain-tile around the perimeter of exterior slabs that

connect directly to the storm drainage system to help further reduce the potential for frost heave.



Consideration should also be given to extending structural stoops or a zone of non-frost

susceptible fill to include the front sidewalks, ADA parking stalls, and pathways connecting the

ADA stalls with the entrances. It is our opinion that placing non-frost susceptible material in large

areas under exterior pavements and sidewalks would be exceedingly expensive and an unusual

design and construction procedure in this area. We should be contacted to provide additional

recommendations should consideration be given to placing non-frost-susceptible (granular)

material in large areas.

5.0 GENERAL COMMENTS

Terracon should be retained to review the final design plans and specifications so comments

can be made regarding interpretation and implementation of our geotechnical recommendations

in the design and specifications. Terracon also should be retained to provide observation and

testing services during grading, excavation, foundation construction and other earth-related

construction phases of the project.

The analysis and recommendations presented in this report are based upon the data obtained

from the borings performed at the indicated locations and from other information discussed in

this report. This report does not reflect variations that may occur between borings, across the

site, or due to the modifying effects of construction or weather. The nature and extent of such

variations may not become evident until during or after construction. If variations appear, we

should be immediately notified so that further evaluation and supplemental recommendations

can be provided.

The scope of services for this project does not include either specifically or by implication any

environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or

prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the

potential for such contamination or pollution, other studies should be undertaken.

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 warranties, either express or implied, are intended or made. Site

safety, excavation support, and dewatering requirements are the responsibility of others. In the

event that 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 Terracon reviews the changes and either verifies or modifies the conclusions of this

report in writing.

Responsive ■ Resourceful ■ Reliable

05155060R01.docx

APPENDIX A

FIELD EXPLORATION

SITE LOCATION PLAN

Kidder Heights Development4502 S 60th St

Omaha, NE

TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEYQUADRANGLES INCLUDE: RALSTON, NE (1/1/1984) and OMAHA SOUTH, NE (1/1/1994).

15080 A CircleOmaha, NE 68144

05155060Project Manager:

Drawn by:

Checked by:

Approved by:

GKA

MDR

MDR

1”=24,000 SF

05155060

9/2/2015

Project No.

Scale:

File Name:

Date:A-1

ExhibitGKA

BORING LOCATION PLAN

Kidder Heights Development4502 S 60th St

Omaha, NE15080 A Circle

Omaha, NE 68144

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND ISNOT INTENDED FOR CONSTRUCTION PURPOSES

05155060

AERIAL PHOTOGRAPHY PROVIDEDBY MICROSOFT BING MAPS

GKA

MDR

MDR

AS SHOWN

05155060

9/2/2015

Scale:

A-2

ExhibitProject Manager:

Drawn by:

Checked by:

Approved by:

Project No.

File Name:

Date:

GKA

BORING LOCATION PLAN

KIDDER HEIGHTS DEVELOPMENT4502 SOUTH 60TH STREET

OMAHA, NEBRASKAA-3

15080 A Circle Omaha, Nebraska 68144

PH. (402) 330-2202 FAX. (402) 330-7606

05155060

9/2/2015

GKA

GKA

MDR

MDR

N.T.S.

Project Manager:

Drawn by:

Checked by:

Approved by:

Project No.

Scale:

File Name:

Date:

Exhibit

05155060BPLANDIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT

INTENDED FOR CONSTRUCTION PURPOSES

- Approximate Boring Location

B-1B-2

B-3

B-4

B-5

B-8

B-7

Source: Kidder Heights, LLC.

B-6

B-10

B-9



A-4

05155060R01.docx

Field Exploration Description

The soil borings were laid out by Terracon personnel using a hand-held GPS unit. GPS

coordinates and elevations were obtained at each location using a hand-held GPS unit with a

vertical accuracy of about ½-foot and a lateral accuracy of about 1 foot. The approximate boring

locations are shown on the Boring Location Plan, Exhibit A-2 and A-3, Appendix A. The locations

and elevations should be considered accurate only to the degree implied by the means and

methods used to define them.

The borings were drilled with a truck-mounted rotary-drilling rig using continuous-flight, solid-stem

augers to advance the boreholes. Representative samples of the soil profile were obtained using

thin-walled tube sampling procedures. The thin-walled tube sampling procedure consisted of

hydraulically pushing 3-inch outside diameter (OD) seamless steel Shelby tubes with a sharp

cutting edge into the bottom of the borehole to obtain a relatively undisturbed sample of cohesive

soils. The samples were tagged for identification, sealed, and taken to the laboratory for testing and

classification.

A field log of each boring was prepared by the drill crew. Each log included visual classifications of

the materials encountered during drilling as well as the driller's interpretation of the subsurface

conditions between samples. The boring logs included with this report represent an interpretation

of the field logs and include modifications based on the laboratory test results and further

examination of the samples by the project geotechnical engineer.

5500(HP)

6500(HP)

4500(HP)

4500(HP)

7000(HP)

7000(HP)

24

21

21

19

18

16

94

100

102

102

102

108

1054

1049

1037

2

7

6

4

3

4

3.0

8.0

20.0

Grass, root zone at surfaceLEAN CLAY (CL), trace sand, trace roots, dark brown, very stiff

LEAN CLAY (CL), trace sand, brown, very stiff

LEAN CLAY (CL), trace sand, light brown, very stiff

Boring Terminated at 20 Feet

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

GR

AP

HIC

LO

G

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

051

550

60 L

OG

S.G

PJ

TE

RR

AC

ON

2015

.GD

T 9

/9/1

5

4502 S. 60th Street Omaha, NESITE:

Page 1 of 1

Advancement Method:Continuous Flight Auger

Abandonment Method:Boring backfilled with soil cuttings upon completion.

15080 A CircleOmaha, Nebraska

Notes:

Project No.: 05155060

Drill Rig: #96

Boring Started: 8/25/2015

BORING LOG NO. B-1Kidder Heights, LLC.CLIENT:Omaha, NE

Driller: J. McGargill

Boring Completed: 8/25/2015

Exhibit: A-5

See Exhibit A-3 for description of field procedures.

See Appendix B for description of laboratoryprocedures and additional data (if any).

See Appendix C for explanation of symbols andabbreviations.

PROJECT: Kidder Heights Development

LAB

OR

AT

OR

YT

OR

VA

NE

/HP

(ps

f)

UN

CO

NF

INE

DC

OM

PR

ES

SIV

ES

TR

EN

GT

H (

psf)

WA

TE

RC

ON

TE

NT

(%

)

DR

Y U

NIT

WE

IGH

T (

pcf)

ATTERBERGLIMITS

LL-PL-PISurface Elev.: 1057 (Ft.)

ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

10

15

20

RE

CO

VE

RY

(In

.)

DEPTH

LOCATION

Latitude: 41.2151° Longitude: -96.0054°

See Exhibit A-2

Not Encountered, While Drilling

WATER LEVEL OBSERVATIONS

6000(HP)

7000(HP)

5500(HP)

4500(HP)

7500(HP)

7500(HP)

25

21

18

17

21

19

89

95

98

99

99

103

40-26-14

39-21-18

1049.5

1044.5

1032.5

9

6

14

6

16

7

3.0

8.0

20.0


LEAN CLAY (CL), trace sand, brown, very stiff




GR

AP

HIC

LO

G

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

051

550

60 L

OG

S.G

PJ

TE

RR

AC

ON

2015

.GD

T 9

/9/1

5


Page 1 of 1




Notes:


Drill Rig: #96





Exhibit: A-6





LAB

OR

AT

OR

YT

OR

VA

NE

/HP

(ps

f)

UN

CO

NF

INE

DC

OM

PR

ES

SIV

ES

TR

EN

GT

H (

psf)

WA

TE

RC

ON

TE

NT

(%

)

DR

Y U

NIT

WE

IGH

T (

pcf)

ATTERBERGLIMITS

LL-PL-PISurface Elev.: 1052.5 (Ft.)

ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

10

15

20

RE

CO

VE

RY

(In

.)

DEPTH

LOCATION


See Exhibit A-2



6000(HP)

6500(HP)

7500(HP)

8000(HP)

8000(HP)

3500(HP) 2980

25

22

19

11

18

25

87

95

102

108

105

95

1028

1018

1013

1011

7

8

6

6

5

13

3.0

13.0

18.0

20.0


LEAN CLAY (CL), trace sand, brown to light brown, very stiff

LEAN TO FAT CLAY (CL/CH), trace sand, mottled light brown, very stiff

LEAN CLAY (CL), trace sand, reddish-brown, stiff



GR

AP

HIC

LO

G

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

051

550

60 L

OG

S.G

PJ

TE

RR

AC

ON

2015

.GD

T 9

/9/1

5


Page 1 of 1




Notes:


Drill Rig: #96





Exhibit: A-7





LAB

OR

AT

OR

YT

OR

VA

NE

/HP

(ps

f)

UN

CO

NF

INE

DC

OM

PR

ES

SIV

ES

TR

EN

GT

H (

psf)

WA

TE

RC

ON

TE

NT

(%

)

DR

Y U

NIT

WE

IGH

T (

pcf)

ATTERBERGLIMITS


ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

10

15

20

RE

CO

VE

RY

(In

.)

DEPTH

LOCATION


See Exhibit A-2



5000(HP)

4000(HP)

8000(HP)

7500(HP)

8500(HP)

8500(HP) 8240

25

23

19

15

14

21

90

92

98

94

112

106

1021.5

1014.5

15

7

7

12

3

10

13.0

20.0

Grass, root zone at surfaceLEAN CLAY (CL), trace sand, trace roots, brown to light brown, stiff to verystiff

LEAN TO FAT CLAY (CL/CH), trace sand, mottled light brown, very stiff



GR

AP

HIC

LO

G

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

051

550

60 L

OG

S.G

PJ

TE

RR

AC

ON

2015

.GD

T 9

/9/1

5


Page 1 of 1




Notes:


Drill Rig: #96





Exhibit: A-8





LAB

OR

AT

OR

YT

OR

VA

NE

/HP

(ps

f)

UN

CO

NF

INE

DC

OM

PR

ES

SIV

ES

TR

EN

GT

H (

psf)

WA

TE

RC

ON

TE

NT

(%

)

DR

Y U

NIT

WE

IGH

T (

pcf)

ATTERBERGLIMITS


ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

10

15

20

RE

CO

VE

RY

(In

.)

DEPTH

LOCATION


See Exhibit A-2



3000(HP)

4000(HP)

4000(HP)

2000(HP)

1000(HP)

500(HP)

28

26

25

26

32

32

85

91

94

92

88

88

1029

1024

1012

6

6

6

8

15

16

3.0

8.0

20.0

Grass, root zone at surfaceLEAN CLAY (CL), trace sand, trace roots, dark brown, stiff

LEAN CLAY (CL), trace sand, brown, stiff

LEAN CLAY (CL), trace sand, light brown, medium stiff

Soft below about 13 ft



GR

AP

HIC

LO

G

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

051

550

60 L

OG

S.G

PJ

TE

RR

AC

ON

2015

.GD

T 9

/9/1

5


Page 1 of 1




Notes:


Drill Rig: #96





Exhibit: A-9





LAB

OR

AT

OR

YT

OR

VA

NE

/HP

(ps

f)

UN

CO

NF

INE

DC

OM

PR

ES

SIV

ES

TR

EN

GT

H (

psf)

WA

TE

RC

ON

TE

NT

(%

)

DR

Y U

NIT

WE

IGH

T (

pcf)

ATTERBERGLIMITS


ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

10

15

20

RE

CO

VE

RY

(In

.)

DEPTH

LOCATION


See Exhibit A-2

13 ft., While Drilling


6000(HP)

7500(HP)

7500(HP)

4500(HP)

7000(HP)

5000(HP)

7000(HP)

24

20

20

21

19

20

21

91

99

100

100

98

103

103

1061.5

1039.5

4

6

7

4

14

7

7

3.0

25.0

Grass, root zone at surfaceLEAN CLAY (CL), trace sand, trace roots, brown, very stiff




GR

AP

HIC

LO

G

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

051

550

60 L

OG

S.G

PJ

TE

RR

AC

ON

2015

.GD

T 9

/9/1

5


Page 1 of 1




Notes:


Drill Rig: #96





Exhibit: A-10





LAB

OR

AT

OR

YT

OR

VA

NE

/HP

(ps

f)

UN

CO

NF

INE

DC

OM

PR

ES

SIV

ES

TR

EN

GT

H (

psf)

WA

TE

RC

ON

TE

NT

(%

)

DR

Y U

NIT

WE

IGH

T (

pcf)

ATTERBERGLIMITS


ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

10

15

20

25

RE

CO

VE

RY

(In

.)

DEPTH

LOCATION


See Exhibit A-2



4000(HP)

4500(HP)

7000(HP)

5500(HP)

7000(HP)

6000(HP)

25

21

19

18

20

21

90

96

97

102

102

101

1047.5

1032.5

1030.5

4

5

7

5

7

10

3.0

18.0

20.0

Grass, root zone at surfaceLEAN CLAY (CL), trace sand, trace roots, brown, stiff


LEAN CLAY (CL), trace sand, reddish-brown, very stiff



GR

AP

HIC

LO

G

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

051

550

60 L

OG

S.G

PJ

TE

RR

AC

ON

2015

.GD

T 9

/9/1

5


Page 1 of 1




Notes:


Drill Rig: #96





Exhibit: A-11





LAB

OR

AT

OR

YT

OR

VA

NE

/HP

(ps

f)

UN

CO

NF

INE

DC

OM

PR

ES

SIV

ES

TR

EN

GT

H (

psf)

WA

TE

RC

ON

TE

NT

(%

)

DR

Y U

NIT

WE

IGH

T (

pcf)

ATTERBERGLIMITS


ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

10

15

20

RE

CO

VE

RY

(In

.)

DEPTH

LOCATION


See Exhibit A-2



7500(HP)

7500(HP)

14

16

101

871046

8

9

5.0

Grass, root zone at surfaceLEAN CLAY (CL), trace sand, trace roots, light brown, very stiff



GR

AP

HIC

LO

G

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

051

550

60 L

OG

S.G

PJ

TE

RR

AC

ON

2015

.GD

T 9

/9/1

5


Page 1 of 1




Notes:


Drill Rig: #96





Exhibit: A-12





LAB

OR

AT

OR

YT

OR

VA

NE

/HP

(ps

f)

UN

CO

NF

INE

DC

OM

PR

ES

SIV

ES

TR

EN

GT

H (

psf)

WA

TE

RC

ON

TE

NT

(%

)

DR

Y U

NIT

WE

IGH

T (

pcf)

ATTERBERGLIMITS


ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

RE

CO

VE

RY

(In

.)

DEPTH

LOCATION


See Exhibit A-2



3000(HP)

4500(HP)

22

22

91

941034

3

7

5.0

Grass, root zone at surfaceLEAN CLAY (CL), trace sand, trace roots, light brown, stiff to very stiff



GR

AP

HIC

LO

G

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

051

550

60 L

OG

S.G

PJ

TE

RR

AC

ON

2015

.GD

T 9

/9/1

5


Page 1 of 1




Notes:


Drill Rig: 96





Exhibit: A-13





LAB

OR

AT

OR

YT

OR

VA

NE

/HP

(ps

f)

UN

CO

NF

INE

DC

OM

PR

ES

SIV

ES

TR

EN

GT

H (

psf)

WA

TE

RC

ON

TE

NT

(%

)

DR

Y U

NIT

WE

IGH

T (

pcf)

ATTERBERGLIMITS


ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

RE

CO

VE

RY

(In

.)

DEPTH

LOCATION


See Exhibit A-2



5500(HP)

3500(HP)

23

25

96

93

1037.5

1035.5

2

3

3.0

5.0

Grass, root zone at surfaceLEAN CLAY, trace sand, trace roots, mottled brown, very stiff

LEAN CLAY (CL), trace sand, mottled light brown, stiff



GR

AP

HIC

LO

G

TH

IS B

OR

ING

LO

G IS

NO

T V

ALI

D IF

SE

PA

RA

TE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

LO

G-N

O W

ELL

051

550

60 L

OG

S.G

PJ

TE

RR

AC

ON

2015

.GD

T 9

/9/1

5


Page 1 of 1




Notes:


Drill Rig: 96





Exhibit: A-14





LAB

OR

AT

OR

YT

OR

VA

NE

/HP

(ps

f)

UN

CO

NF

INE

DC

OM

PR

ES

SIV

ES

TR

EN

GT

H (

psf)

WA

TE

RC

ON

TE

NT

(%

)

DR

Y U

NIT

WE

IGH

T (

pcf)

ATTERBERGLIMITS


ELEVATION (Ft.)

SA

MP

LE T

YP

E

WA

TE

R L

EV

EL

OB

SE

RV

AT

ION

S

DE

PT

H (

Ft.)

5

RE

CO

VE

RY

(In

.)

DEPTH

LOCATION


See Exhibit A-2




05155060R01.docx

APPENDIX B

LABORATORY TESTING


Responsive ■ Resourceful ■ Reliable B-1 05155060R01.docx

Laboratory Testing

Water content tests (ASTM D2216) were performed on the samples. Density determinations

(ASTM D7263) were performed on most of the thin-walled tube samples, and unconfined

compression tests (ASTM D2166) were performed on some of the thin-walled tube samples. The

unconfined compressive strength of most of the samples was estimated with a hand penetrometer

test. In addition, Atterberg limits tests (ASTM D4318) were performed on two samples. Results of

these laboratory tests are provided on the boring logs.

The samples were classified in the laboratory based on visual observation, texture and plasticity

(ASTM D2488). Additional laboratory testing could be performed to more accurately classify the

samples. The soil descriptions presented on the boring logs for native soils are in accordance

with our enclosed General Notes and Unified Soil Classification System (USCS, ASTM D2487).

The estimated group symbol for the USCS is also shown on the boring logs for native soils, and

a brief description of the Unified System is included in this report.

Procedural standards noted above are for reference to methodology in general. In some cases,

variations to methods are applied as a result of local practice or professional judgment.


05155060R01.docx

APPENDIX C

SUPPORTING DOCUMENTS

TraceWithModifier

Water Level Aftera Specified Period of Time

GRAIN SIZE TERMINOLOGYRELATIVE PROPORTIONS OF SAND AND GRAVEL

TraceWithModifier

Standard Penetration orN-Value

Blows/Ft.

Descriptive Term(Consistency)

Loose

Very Stiff

Exhibit C-1

Standard Penetration orN-Value

Blows/Ft.

Ring SamplerBlows/Ft.

Ring SamplerBlows/Ft.

Medium Dense

Dense

Very Dense

0 - 1 < 3

4 - 9 2 - 4 3 - 4

Medium-Stiff 5 - 9

30 - 50

WA

TE

R L

EV

EL

Auger

Shelby Tube

Ring Sampler

Grab Sample

8 - 15

Split Spoon

Macro Core

Rock Core

PLASTICITY DESCRIPTION

Term

< 1515 - 29> 30

Descriptive Term(s)of other constituents

Water InitiallyEncountered

Water Level After aSpecified Period of Time

Major Componentof Sample

Percent ofDry Weight

(More than 50% retained on No. 200 sieve.)Density determined by Standard Penetration Resistance

Includes gravels, sands and silts.

Hard

Very Loose 0 - 3 0 - 6 Very Soft

7 - 18 Soft

10 - 29 19 - 58

59 - 98 Stiff

less than 500

500 to 1,000

1,000 to 2,000

2,000 to 4,000

4,000 to 8,000> 99

LOCATION AND ELEVATION NOTES

SA

MP

LIN

G

FIE

LD

TE

ST

S

(HP)

(T)

(b/f)

(PID)

(OVA)

DESCRIPTION OF SYMBOLS AND ABBREVIATIONS

Descriptive Term(Density)

Non-plasticLowMediumHigh

BouldersCobblesGravelSandSilt or Clay

10 - 18

> 50 15 - 30 19 - 42

> 30 > 42

_

Hand Penetrometer

Torvane

Standard PenetrationTest (blows per foot)

Photo-Ionization Detector

Organic Vapor Analyzer

Water levels indicated on the soil boringlogs are the levels measured in theborehole at the times indicated.Groundwater level variations will occurover time. In low permeability soils,accurate determination of groundwaterlevels is not possible with short termwater level observations.

CONSISTENCY OF FINE-GRAINED SOILS

(50% or more passing the No. 200 sieve.)Consistency determined by laboratory shear strength testing, field

visual-manual procedures or standard penetration resistance

DESCRIPTIVE SOIL CLASSIFICATION

> 8,000

Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracyof such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey wasconducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographicmaps of the area.

Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dryweight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils haveless than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, andsilts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may beadded according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are definedon the basis of their in-place relative density and fine-grained soils on the basis of their consistency.

Plasticity Index

01 - 1011 - 30

> 30

RELATIVE PROPORTIONS OF FINES

Descriptive Term(s)of other constituents

Percent ofDry Weight

< 55 - 12> 12

No Recovery

RELATIVE DENSITY OF COARSE-GRAINED SOILS

Particle Size

Over 12 in. (300 mm)12 in. to 3 in. (300mm to 75mm)3 in. to #4 sieve (75mm to 4.75 mm)#4 to #200 sieve (4.75mm to 0.075mmPassing #200 sieve (0.075mm)

ST

RE

NG

TH

TE

RM

S Unconfined CompressiveStrength, Qu, psf

4 - 8

GENERAL NOTES

gkallam

Rectangle

Exhibit C-2

UNIFIED SOIL CLASSIFICATION SYSTEM

Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A

Soil Classification

Group

Symbol Group Name

B

Coarse Grained Soils:

More than 50% retained

on No. 200 sieve

Gravels:

More than 50% of

coarse fraction retained

on No. 4 sieve

Clean Gravels:

Less than 5% fines C

Cu 4 and 1 Cc 3 E

GW Well-graded gravel F

Cu 4 and/or 1 Cc 3 E

GP Poorly graded gravel F

Gravels with Fines:

More than 12% fines C

Fines classify as ML or MH GM Silty gravel F,G,H

Fines classify as CL or CH GC Clayey gravel F,G,H

Sands:

50% or more of coarse

fraction passes No. 4

sieve

Clean Sands:

Less than 5% fines D

Cu 6 and 1 Cc 3 E

SW Well-graded sand I

Cu 6 and/or 1 Cc 3 E

SP Poorly graded sand I

Sands with Fines:

More than 12% fines D

Fines classify as ML or MH SM Silty sand G,H,I

Fines classify as CL or CH SC Clayey sand G,H,I

Fine-Grained Soils:

50% or more passes the

No. 200 sieve

Silts and Clays:

Liquid limit less than 50

Inorganic: PI 7 and plots on or above “A” line

J CL Lean clay

K,L,M

PI 4 or plots below “A” line J ML Silt

K,L,M

Organic: Liquid limit - oven dried

0.75 OL Organic clay

K,L,M,N

Liquid limit - not dried Organic silt K,L,M,O

Silts and Clays:

Liquid limit 50 or more

Inorganic: PI plots on or above “A” line CH Fat clay

K,L,M

PI plots below “A” line MH Elastic Silt K,L,M

Organic: Liquid limit - oven dried

0.75 OH Organic clay

K,L,M,P

Liquid limit - not dried Organic silt K,L,M,Q

Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat

A Based on the material passing the 3-inch (75-mm) sieve

B If field sample contained cobbles or boulders, or both, add “with cobbles

or boulders, or both” to group name. C

Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded

gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly

graded gravel with silt, GP-GC poorly graded gravel with clay. D

Sands with 5 to 12% fines require dual symbols: SW-SM well-graded

sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded

sand with silt, SP-SC poorly graded sand with clay

E Cu = D60/D10 Cc =

6010

2

30

DxD

)(D

F If soil contains 15% sand, add “with sand” to group name.

G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.

H If fines are organic, add “with organic fines” to group name.

I If soil contains 15% gravel, add “with gravel” to group name.

J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.

K If soil contains 15 to 29% plus No. 200, add “with sand” or “with gravel,”

whichever is predominant. L

If soil contains 30% plus No. 200 predominantly sand, add “sandy” to

group name. M

If soil contains 30% plus No. 200, predominantly gravel, add

“gravelly” to group name. N

PI 4 and plots on or above “A” line. O

PI 4 or plots below “A” line. P

PI plots on or above “A” line. Q

PI plots below “A” line.

gkallam

Rectangle

Responsive ■ Resourceful ■ Reliable C-3

References

Soil Survey of Douglas County, Nebraska; United States Department of Agriculture;URL: http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx

Soil Survey of Douglas and Sarpy Counties, Nebraska, United States Department of Agriculture,Soils Conservation Service, 1975.

United States Geological Survey, 7.5-minute series Quadrangle Maps, "Ralston, Nebraska," 1984and "Omaha South, Nebraska," 1984.

Douglas County GIS Mapping Website, accessed via http://www.dogis.org/

Miller, Robert D., Geology of the Omaha-Council Bluffs Area, Nebraska-Iowa; Geological SurveyProfessional Paper 472; published by Washington, U.S. Government Printing Office, 1964.

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