final geotechnical engineering report

Final Geotechnical

Engineering Report Waverly Swim Club Pond Dam

Albemarle Road

Charlotte, North Carolina

July 16, 2015

Project No. 71135018

Prepared for:

Dewberry and Davis, Inc.


Prepared by:

Terracon Consultants, Inc.


Final Geotechnical Engineering Report Waverly Swim Club Pond Dam ■ Charlotte, North Carolina July 16, 2015 ■ Terracon Project No. 71135018

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TABLE OF CONTENTS

Page EXECUTIVE SUMMARY ............................................................................................................ ii 1.0 INTRODUCTION ............................................................................................................. 1 2.0 PROJECT INFORMATION ............................................................................................. 1

2.1 Site Location and Description .............................................................................. 1

2.2 Project Description ............................................................................................... 2 3.0 SUBSURFACE CONDITIONS ........................................................................................ 2

3.1 Geology ............................................................................................................... 2

3.2 Typical Profile ...................................................................................................... 3

3.3 Groundwater ........................................................................................................ 4 4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION ...................................... 5

4.1 Geotechnical Considerations ............................................................................... 5

4.2 Slope Stability ...................................................................................................... 6

4.3 Earthwork ............................................................................................................ 6

4.3.1 Site Preparation ........................................................................................ 6

4.3.2 Material Types .......................................................................................... 7

4.3.3 Compaction Requirements ....................................................................... 8

4.3.4 Earthwork Construction Considerations .................................................... 9

4.3.5 Excavations .............................................................................................. 9

4.4 Foundations ........................................................................................................ 10

4.4.1 Foundation Design Recommendations ................................................... 10

4.4.2 Pipe Support Cradle Considerations ....................................................... 11

4.4.3 Foundation Construction Considerations ................................................ 11

4.5 Filter Diaphragm and Underdrain ........................................................................ 12

4.5.1 Filter Diaphragm Considerations ............................................................ 12

4.5.2 Underdrain Considerations ..................................................................... 12

4.6 Lateral Earth Pressures ..................................................................................... 12 5.0 GENERAL COMMENTS ............................................................................................... 14

APPENDIX A – FIELD EXPLORATION

Exhibit A-1 Site Vicinity Plan

Exhibit A-2 Boring Location Plan

Exhibit A-3 Field Exploration Description

Exhibits A-4 to A-11 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


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EXECUTIVE SUMMARY

A geotechnical evaluation has been performed for the existing Waverly Swim Club Pond Dam in

Charlotte, North Carolina. A total of eight (8) borings, designated W-01 through W-05 and W-HA-

01 through W-HA-03, were performed to depths ranging from approximately 4 to 30 feet below

the ground surface along the existing dam.

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

the proposed project. The following geotechnical considerations were identified:

Based on the data obtained from our subsurface exploration, the major geotechnical

concern for this site is the existing alluvial soils encountered in Borings W-HA-02 and W-HA-

03 and the loose to very loose fills soils encountered in Boring W-05. These soils will likely

compress under the weight of new fill and foundations and present a relatively high risk for

adverse long-term total and differential settlement of the proposed dam and spillway structures,

if constructed without remedial measures. In addition, pumping may occur at pavement

subgrades because of the relatively high moisture content of the alluvial soils.

To reduce the risk of excessive total and differential settlement associated with the alluvial and

very loose fill soils, we recommend undercutting the alluvial soils beneath the proposed pipe

cradle, headwall and weir foundations up to 4 feet below proposed bottom of footing elevations

prior to placing new engineered fill to finished grades.

Once existing alluvial and very loose fill soils are removed as recommended and the site is

backfilled with new engineered fill, it is our opinion that the proposed pipe cradles,

headwalls, overflow channel, and weir may be supported on conventional shallow

foundations with a net allowable bearing pressure of 2,500 psf. Assuming proper site

preparation and any necessary subgrade repair, total and differential settlement should be

less than 1 inch and ¾ inches, respectively.

Based on the estimated bottom of footing depths and the groundwater level encountered, we

anticipate that groundwater will be encountered during construction.

The below grade walls for the proposed concrete spillway channel and reinforced box

culvert should be designed to resist the lateral loads produced by the retained soil and by

hydrostatic forces.

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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FINAL GEOTECHNICAL ENGINEERING REPORT

WAVERLY SWIM CLUB POND DAM

CHARLOTTE, NORTH CAROLINA Project No. 71135018

July 16, 2015

1.0 INTRODUCTION

A geotechnical engineering report has been completed for the existing Waverly Swim Club Pond

Dam located in Charlotte, North Carolina. Five (5) design borings, designated W-01 through W-

05, were performed to depths of approximately 20 to 30 feet below the existing ground surface at

the existing dam. Additionally, three (3) hand auger borings, designated W-HA-01 to W-HA-03,

were performed in the footprint of the existing spillway. Logs of the borings along with a Site

Vicinity Plan and Boring Location Plan are included in Appendix A of this report.

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

recommendations relative to:

Subsurface Soil Conditions

Groundwater Conditions

Earthwork

Shallow Foundations

Slope Stability

Dam Evaluation

Lateral Earth Pressures

2.0 PROJECT INFORMATION

2.1 Site Location and Description

ITEM DESCRIPTION

Location

The Waverly Swim Club Pond is located north and adjacent to

Albemarle Road, south of Ivy Hollow Drive, east of Almond Road, and

west of Tamora Drive in Charlotte, North Carolina.

Existing Development

Approximately 17-acre pond and existing earthen dam with a concrete

spillway. The dam traverses approximately 600 feet along the south

edge of the pond and along the southern portions of the east and west

edges of the pond.

Current Ground Cover Mixture of landscaped areas, grass, and some trees.

Existing Topography The area around the dam varies from about 690 feet to 703 feet and

the normal water level is about 699.6 feet.

Terracon has been provided with a topographic map of the pond, dam, and surrounding area.

The pond appears to have been constructed by excavating from natural grades to



approximately 703 feet mean sea level elevation (MSLE) and constructing a “C” shaped berm

around the south end of the pond. In general, the crest and both the upstream and

downstream slopes are covered with small trees and grassy undergrowth. A concrete spillway

approximately 120 feet long with an 8 foot notch weir is located towards the middle of the

dam. The spillway outflow is lined with riprap and leads to a box culvert that conveys water

underneath Albemarle Road and towards Marlwood Pond.

The majority of the upstream and downstream slopes that are covered in vegetation appear to

be at an inclination of approximately 3H:1V (horizontal to vertical) and vary in height from

approximately 3 to 6 feet. These slopes then transition to about 2.5H:1V or flatter at the pond

water elevation. The slopes adjacent to the outflow channel are sloped up to approximately

2H:1V.

2.2 Project Description

ITEM DESCRIPTION

Proposed Structures

Improvements to the existing dam will include construction of a new

120 foot weir structure, adding a siphon drain, and modification of the

existing outfall channel. The outfall channel will be paved with

concrete and a reinforced concrete box culvert will be used to channel

the water to a new concrete vault that will be constructed adjacent to

the south side of the dam.

Loads Not Provided. Estimated to be relatively light.

Grading Minimal cut and fill – estimated at less than 5 feet.

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

construction, please let us know so that we can make any necessary modifications to the

report.

3.0 SUBSURFACE CONDITIONS

3.1 Geology

The project site is located in the Piedmont Physiographic Province, an area underlain by ancient

igneous and metamorphic rocks. The residual soils in this area are the product of in-place

chemical weathering of rock. The typical residual soil profile consists of clayey soils near the

surface where soil weathering is more advanced, underlain by sandy silts and silty sands that

generally become harder with depth to the top of parent bedrock. Alluvial soils are typically

present within floodplain areas along creeks and rivers in the Piedmont. According to the 1985

Geologic Map of North Carolina, the site is within the Charlotte Belt. The bedrock underlying the

site generally consists of meta-argillite.



The boundary between soil and rock in the Piedmont is not sharply defined. A transitional zone

termed “partially weathered rock” is normally found overlying the parent bedrock. Partially

weathered rock is defined for engineering purposes as residual material with standard

penetration test resistance’s exceeding 100 blows per foot. The transition between hard/dense

residual soils and partially weathered rock occurs at irregular depths due to variations in degree

of weathering.

Groundwater is typically present in fractures within the partially weathered rock or underlying

bedrock in the Piedmont. Fluctuations in groundwater levels on the order of 2 to 4 feet are typical

in residual soils and partially weathered rock in the Piedmont, depending on variations in

precipitation, evaporation, and surface water runoff. Seasonal high groundwater levels are

expected to occur during or just after the typically cooler months of the year (November through

April).

3.2 Typical Profile

Based on the results of the borings, the subsurface conditions on the project site can be

generalized as follows:

Boring Existing Ground

Elevation 1

Boring Depth

2

(feet)

Approx. Water

Elevation 1

Approx. Elevation of

Fill Soils Encountered

1

Approx. Elevation of

Residual Soils Encountered

1

Approx. Elevation

1

of Top of PWR

3

W-01

702.5 25 NE 4

702.5 – 684.0 684.0 – 677.5 NE

W-02

703 24.3 694.7 5

703.0 – 689.5 689.5 – 679.5 679.5

W-03

704 20 NE NE 703.0 – 684.0 NE

W-04

703.5 20 NE 703.5 – 700.0 700.0 – 683.5 NE

W-05

701.5 30 686.5 701 – 683.5 683.5 – 671.5 NE

W-HA-01

703 3.6 NE 703 - 702 702 – 699.5 NE

W-HA-02

703 8.6 NE 703 - 702 702 – 694.5 NE

W-HA-03

703 10 NE 702.5 – 699.5 699.5 - 693 NE

1. Approximate elevations based off of topographic map provided by Dewberry 2. From the existing ground surface 3. PWR: Partially Weathered Rock 4. NE: Not Encountered 5. 24-hour water level reading

The soil test borings along the dam encountered approximately 2 to 3 inches of topsoil and

rootmat at the ground surface. Below the surface materials, the western borings (W-03 and W-

04) encountered up to 3.5 feet of fill soils and the eastern borings (W-01, W-02, and W-05)

encountered fill soils between 13.5 and 18.5 feet below the existing ground surface. Fill soils are

those soils that have been placed or reworked in conjunction with past construction grading. The



engineering properties of the fill depend primarily on its composition, density, and moisture

content.

The fill soils at this site consist of sandy clay and sandy silt and classify as CL and ML,

respectively, in general accordance with the Unified Soils Classification System (USCS). The

standard penetration resistance values (N-values) in the fill material range from 2 to 15 blows per

foot (bpf), indicating a soft to stiff relative consistency.

Residual soils were encountered below the fill soils with the exception of boring W-03, in which

the residual soils were encountered directly below the topsoil. The residual soils consist of sandy

silt, silty sand, and sandy clay. These soils visually classify as ML, SM, and CL, respectively, in

general accordance with the USCS. N-values ranging between 8 and 32 bpf were encountered

in the silty sand, indicating a loose to dense relative density. The N-values range from 7 to 51 bpf

in the silts and clays indicating a medium stiff to hard relative consistency.

Partially weathered rock (PWR) was encountered below the residual soils in boring W-02. The

PWR was sampled and visually classified as hard sandy silt, ML in accordance with the USCS.

The soils encountered in the hand auger borings at the existing spillway footprint consisted of 1

to 3.6 feet of fill materials. The fill consisted of lean clay with varying amounts of sand and

classify as CL, in accordance with the USCS. Hand auger boring W-HA-02 and W-HA-03

encountered alluvial soils beneath the fill material. The alluvial soils consisted of lean clay with

sand and classify as CL. Residual soils were encountered to the boring termination depths. The

residual soils consisted of silty sand and sandy silt to silt with sand and classify as SM and ML,

respectively.

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

Appendix A of this report. Stratification boundaries on the boring logs represent the approximate

location of changes in soil types; in-situ, the transition between materials may be gradual.

3.3 Groundwater

The boreholes were observed while drilling and after completion for the presence and level of

groundwater. Groundwater was observed while drilling in boring W-05 at an approximate

elevation of 686.5 feet. Groundwater was not observed in the remaining borings immediately

after completion. Borings W-01, W-03, W-04, W-05, W-HA-01, W-HA-02, and W-HA-03 were

immediately backfilled with the auger cuttings, making subsequent water level readings

unobtainable; however, boring W-02 was left open for a 24-hour groundwater reading, and water

was encountered at an approximate elevation of 695.

It should be recognized that fluctuations of the groundwater table will occur due to seasonal

variations in the amount of rainfall, runoff 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. The possibility

of groundwater level fluctuations should be considered when developing the design and

construction plans for the project.

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

4.1 Geotechnical Considerations

Based on the data obtained from our subsurface exploration, the major geotechnical concern

for this site is the approximate 2 to 4 feet of alluvial soils encountered in hand auger Borings

W-HA-02 and W-HA-03 and the loose to very loose fill soils encountered in Boring W-05 at the

bearing elevation of the proposed concrete vault and pipe cradles for the siphon drain. These

soils will likely compress under the weight of the proposed new weir structure and present a

relatively high risk for adverse long-term total and differential settlement of the spillway, concrete

vault, and pipe cradles, if constructed without remedial measures. In addition, pumping may

occur at pavement subgrades because of the relatively high moisture content of the alluvial soils.

To reduce the risk of excessive total and differential settlement associated with the soft soils, and

to provide a stable subgrade for the weir, concrete vault, and pipe cradles, we recommend

undercutting four (4) feet beneath the proposed bottom of footing elevations of the proposed weir

and concrete vault. After these undercutting procedures are performed, the over-excavation

should be underlain with a geotextile (Mirafi HP570 or equivalent) and backfilled with new

engineered fill in accordance with the Earthwork section of this report.

Due to excessively soft alluvial soils, a “Bridge Lift” of up to 18 inches of new engineered fill may

be necessary at the bottom of the undercut areas. A Bridge Lift is a relatively thick lift of fill soil

that is placed over soft subgrade soils as the first lift in the grading operation. The lift is thick

enough to allow construction equipment to work, but since the subgrade is relatively soft, the

bridge lift may not achieve the desired compaction requirements (i.e., 95% relative compaction

as per Standard proctor). However, subsequent lifts can be placed and compacted properly.

Once the site is remediated as described above, it is our opinion that the proposed overflow

spillway, pipe cradles, weir, and concrete vault may be supported on conventional spread and

strip footings with a net allowable bearing pressure of 2,500 psf. Further details and

recommendations are provided herein. Assuming proper site preparation and any necessary

subgrade repair, total and differential settlement should be within anticipated tolerable limits.

The geotechnical engineer should be retained during the construction phase of the project to

observe earthwork and to perform necessary tests and observations during subgrade

preparation and footing excavation. Soil testing should include proofrolling, placement and

compaction of fill soils, backfilling of excavations upto the completed subgrade, and footing

subgrade evaluation.



The contractor should expect that dewatering will be required during foundation excavation. It

is recommended that water levels be kept at least two feet below the bottom of the

foundations until the headwalls, weir and pipe cradles have been constructed. A more

complete discussion of these points and additional information is included in the following

sections.

4.2 Slope Stability

Based on our review of the proposed dam improvements, we understand that all permanent

slopes will be designed at a 3H:1V (Horizontal: Vertical) inclination or flatter. The North

Carolina Administrative Code, Title 15A, Subchapter 2K – Dam Safety, Section .0208 –

“Structural Stability and Slope Protection,” requires a minimum factor of safety of 1.5 for slope

stability for normal conditions. Improved permanent dam slopes will meet the minimum required

factor of safety of 1.5 provided they are constructed according to the reconditions in this report.

4.3 Earthwork

4.3.1 Site Preparation

Existing vegetation, topsoil, pavement materials and any otherwise unsuitable material should

be removed from the construction areas prior to placing fill. Based on the existing geometry

and proposed remediation to the existing dam, we recommend that the existing riprap remain

in place. The exposed subgrade soils in areas to receive fill or at the subgrade elevation in

cut areas should be evaluated by the geotechnical engineer to detect soft or loose soils and

identify unsuitable or poorly compacted fill. This evaluation may consist of visual observations,

utilizing a probe rod, and/or proofrolling.

Existing alluvial soils were encountered in hand auger borings W-HA-02 and W-HA-03 and

very loose to loose soils were encountered in boring W-05. To reduce the risk of excessive total

and differential settlement associated with these soils, and to provide a stable subgrade for the

foundations, we recommend performing the remedial recommendations as outlined in Section

4.1 of this report prior to constructing the new weir and overflow spillway. We do not recommend

reusing the alluvial soils as engineered fill in foundation areas; however, the existing fill soils

encountered within the dam appear suitable for reuse as engineered fill.

The soils encountered in the borings will be sensitive to disturbance from construction activity

and water seepage. If precipitation occurs prior to or during construction, the near-surface

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. If subgrade soils are unsuitable, they will require removal and

replacement; however, if they are unstable due to excessive moisture, the most economical

solution for remediation may be to scarify, dry and recompact the material. This remediation is

most effective during the typically hotter months of the year (May to October). If construction is



performed during the cooler period of the year, the timeline for scarifying, drying, and

recompacting typically increases considerably and may lead to alternative remediation

solutions. These solutions can include overexcavation of some or all of the unstable material

to be backfilled with either approved engineerd fill or geotextile and ABC Stone. A Terracon

representative can help with monitoring and developing recommendations to aid in limiting

subgrade disturbance.

Proofrolling should be performed with a fully-loaded, tandem-axle dump truck or similar

pneumatic-tired construction equipment. A Terracon representative should observe this

operation to aid in delineating unstable soil areas. Proofrolling should be performed after a

suitable period of dry weather to avoid degrading an otherwise acceptable subgrade. Soils

which continue to rut or deflect excessively under the proofrolling operations should be

remediated as recommended by the geotechnical engineer.

Proofrolling may not be feasible in the low lying areas adjacent to the existing pond or within

confined foundation excavations. In these instances the geotechnical engineer may use a probe

rod and engineering judgment to evaluate the stability of the exposed subgrade prior to fill

placement.

Unstable or unsuitable areas that are identified during the evaluation should be undercut to

suitable soils. The extent of undercut required should be determined in the field by an

experienced geotechnical engineer while monitoring construction activities. Construction traffic

should be avoided, if possible, on the exposed subgrade to reduce disturbance. After the

proofrolling and/or probing and evaluation by the geotechnical engineer has been completed and

approved, project grading should begin immediately to minimize exposure to degradation from

construction activities and inclement weather.

4.3.2 Material Types

Engineered fill should meet the following material property requirements:

Fill Type 1

USCS

Classification Acceptable Location for Placement

On-Site Soils SM, SC, ML, CL

(LL<50 & PI<20) All locations and elevations.

Imported Low

Plasticity Soils

SM, SC, CL, ML

(LL<50 & PI<20) All locations and elevations.

1. Controlled, compacted fill should consist of approved materials that are free of organic matter and

debris. Materials larger than 6 inches in diameter should not be used as fill. Frozen material should

not be used, and fill should not be placed on a frozen subgrade. A sample of each material type

should be submitted to the geotechnical engineer for evaluation.



If new fill is proposed for the existing dam, proper benching techniques should be used to tie the

new fill into the existing slopes. Each bench should be keyed into the existing dam a minimum of

4 feet wide, or sufficiently wide to permit complete coverage with the compaction equipment

used. The base of the key should be graded horizontal, or inclined slightly into the existing dam

slope. The outside of the bottom key should be below the existing fill and loose soils to a depth

of at least two (2) feet. This benching recommendation is presented in the following sketch.

4.3.3 Compaction Requirements

We recommend that 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.

Engineered fill should meet the following compaction requirements:

ITEM DESCRIPTION

Fill Lift Thickness

8 to 10 inches or less in loose thickness when heavy, self-

propelled compaction equipment is used

4 to 6 inches in loose thickness when hand-guided equipment (e.g.

jumping jack or plate compactor) is used

Slopes should be such that sloughing or sliding does not occur.

Existing Slope

2' min.

W

Existing Dam Material

Typical Benching Detail

NOTE: The Key width "W" should be a minimum of 4 feet wide, or sufficiently wide to permit coverage with the compaction equipment.



ITEM DESCRIPTION

Compaction Requirements Minimum 95% of the material’s maximum standard Proctor dry

density (ASTM D 698)

Moisture Content

Requirements

Within 3% of the optimum moisture content value as determined by

the standard Proctor test at the time of placement and compaction

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.

Some manipulation of the moisture content (such as wetting, drying) will be required during

the filling operation to obtain the required degree of compaction. The manipulation of the

moisture content is highly dependent on weather conditions and site drainage conditions.

Therefore, the grading contractor should be prepared to both dry and wet the fill materials to

obtain the specified compaction during grading.

4.3.4 Earthwork Construction Considerations

The near-surface sandy silts and clays at the site will lose strength and rut or deflect

excessively under construction traffic when they become wet. Performing earthwork operations

during warmer periods of the year (May through October) will reduce the potential for problems

associated with unstable subgrades. Earthwork can be performed at other times of the year, but

does lead to an increased potential for having to perform overexcavation and replacement or

some other form of remedial work. Protecting the exposed subgrade soils from infiltration of

surface water by keeping the site grades sloped to promote runoff and by “sealing” disturbed

silty/clayey soil surfaces with rubber-tired equipment in advance of rain events will also reduce

the potential for needing to perform remedial work on wet subgrades. Placing additional

“crusher run” stone base course as a protective layer and working surface in exposed

subgrade areas could also be considered to protect the subgrade soils. Should unstable

subgrade conditions develop, stabilization measures should be employed.

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.

The geotechnical engineer should be retained during the construction phase of the project to

observe earthwork and to perform necessary tests and observations during subgrade

preparation. Soil testing should include proofrolling, placement and compaction of controlled

compacted fills, and backfilling of overexcavations.

4.3.5 Excavations

The soils within the upper 20 to 25 feet may be excavated with conventional construction

equipment, such as bulldozers, backhoes, and trackhoes. All 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 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.

We recommend that all permanent slopes constructed be designed at a 3H:1V (Horizontal:

Vertical) inclination or flatter. Steeper slopes should be evaluated separately for local and

global stability.

Construction site safety is the sole responsibility of the contractor who controls the means,

methods, and sequencing of construction operations. Under no circumstances shall the

information provided herein be interpreted to mean that Terracon is assuming any responsibility

for construction site safety or the contractor's activities; such responsibility shall neither be

implied nor inferred.

4.4 Foundations

4.4.1 Foundation Design Recommendations

In our opinion, once the existing alluvial soils at the weir and very loose fill soils at the

proposed vault location are remediated and the site is backfilled with new engineered fill as

outlined in Sections 4.1 and 4.3 of this report, the proposed weir, outflow spillway, pipe

cradles, headwall structures and concrete vault can be supported by shallow, spread footing

foundation systems. Design recommendations for a shallow foundation system are presented

in the following table and paragraphs.

DESCRIPTION WEIR, SPILLWAY, PIPE

CRADLES, CONCRETE VAULT HEADWALLS

Net allowable bearing pressure 1 2,500 psf 2,500 psf

Minimum dimensions 30 inches 18 inches

Minimum protective embedment 18 inches 18 inches

Approximate total settlement 2 <1 inch < ½ inch over 50 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 unsuitable fill or soft

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

2. 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.



Foundations for the proposed headwalls and weir should be designed to resist any uplift

forces due to hydrostatic pressures. Foundation excavations should be observed by the

geotechnical engineer. If the soil conditions encountered differ from those presented in this

report, supplemental recommendations will be required.

4.4.2 Pipe Support Cradle Considerations

The proposed pipe support cradles for the pond siphon feature can be supported on the stable

residual soils encountered in our borings. These residual soils were encountered at an

approximate elevation of 683.5 feet MSL. It is estimated that to remove all of the very loose fill

soils beneath the pipe cradles would result in approximately 60 to 70 cubic yards of undercut.

Given that this amount of undercut is not desirable, we have determined that a partial removal

of the existing unsuitable soils may be performed and still allow for a suitable bearing strata for

each cradle and spillway pipe. The partial removal of these soils should include undercutting

the existing alluvial and fill soils four (4) feet beneath the proposed bottom of footing

elevations of the proposed weir and concrete vault, placement of a geotextile, and proper

backfilling with engineered fill as outlined in Sections 4.1 and 4.3 of this report.

4.4.3 Foundation Construction Considerations

The base of all foundation excavations should be free of water and loose soil and rock prior to

placing concrete. Concrete should be placed soon after excavating to reduce bearing soil

disturbance. Should the soils at bearing level become disturbed, saturated, or frozen, the

affected soil should be removed prior to placing concrete.

Groundwater seepage into foundation excavations is expected at this site, and the need for

dewatering in foundation excavations should be expected by the contractor. It is

recommended that water levels be kept at least two feet below the bottom of the foundations

until the headwalls, weir, overflow spillway, and pipe cradles have been constructed. A

temporary dewatering system that has performed adequately on previous projects consists of

sump pumps. Pumping from sumps should be maintained until the foundations are properly

installed. If sump pumps are not able to adequately remove the water and keep the site dry for

construction operations, conventional dewatering with drilled wells may be required.

Exposure to inclement weather can also introduce unwanted moisture into the footing

subgrade. If construction occurs during inclement weather, and concreting of foundations is

not possible at the time they are excavated, a layer of lean concrete should be placed on

exposed bearing surfaces for protection. Where high moisture conditions are encountered at

footing bearing elevations, the bottom of the excavations could be stabilized with a relatively

clean, well-graded crushed stone or gravel, or a lean concrete mud mat to provide a working

base for construction.

The foundation bearing materials should be evaluated at the time of the foundation

excavation. A representative of the geotechnical engineer should use a combination of hand



auger borings and dynamic cone penetrometer (DCP) testing to determine the suitability of the

bearing materials for the design bearing pressure. DCP testing should be performed to a depth

of at least 4 feet below the bottom of footing excavation.

4.5 Filter Diaphragm and Underdrain

4.5.1 Filter Diaphragm Considerations

A Filter Diaphragm can be used to reduce the risk of erosion developing through the dam and

underneath the overflow spillway. If used, it is recommended that the Filter Diaphragm consist

of NCDOT “2S” sand (Table 1005-2, NCDOT Standard Specifications for Roads and

Structures, July 2006), or as described in the National Engineering Handbook, Part 628,

Chapter 45. The minimum dry density of the Filter Diaphragm sand should be equal to 95

percent of the dry density obtained by compacting a single specimen of sand using the energy

and methods described in ASTM D698A.

As per the Handbook, the Filter Diaphragm should be constructed downstream of the

centerline of the dam. The width of the Filter Diaphragm should be such that construction

equipment can readily place and compact the sand; however, the diaphragm width should be

at least 36 inches, and at least 24 inches of properly compacted engineered fill should cover

the top of the filter diaphram.

4.5.2 Underdrain Considerations

If a Filter Diaphragm is used, an Underdrain should be installed to collect water from the Filter

Diaphragm and carry it to a suitable outlet. It is recommended that the Underdrain consist of a

non-woven geotextile fabric encasing drainage stone (NCDOT No. 57) surrounding a 6-inch

diameter perforated PVC pipe. The perforated pipe should connect to a solid PVC outlet pipe

and extend to a suitable outlet.

4.6 Lateral Earth Pressures

The following section specifies the lateral earth pressure coefficients to be used for the below

grade walls for the proposed concrete spillway channel and reinforced concrete box culvert.

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. Active earth

pressure is commonly used for design of free-standing cantilever retaining walls and anticipates

wall movement. The "at-rest" condition anticipates no wall rotation. The recommended design

lateral earth pressures do not include a factor of safety.



Earth Pressure Coefficients

Earth Pressure

Conditions

Earth Pressure Coefficient for Backfill Type

Equivalent Fluid Density

(pcf)

Surcharge Pressure,

p1 (psf)

Earth Pressure, p2 (psf)

Active (Ka) On-site sandy silt (ML) and

sandy clay (CL) – 0.38 45 (0.38)S (45)H1 + (22)H2

At-Rest (Ko)

On-site sandy silt (ML) and sandy clay (CL – 0.55

66 (0.55)S (66)H1 + (31)H2

Passive (Kp)

On-site sandy silt (ML) and sandy clay (CL) – 2.66

320 --- ---

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 Unit weight of water (ɣw) is 62.4 pcf Horizontal backfill, compacted to 95 percent of standard Proctor maximum dry density Loading from heavy compaction equipment not included No dynamic loading No safety factor included Ignore passive pressure in frost zone

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

High plasticity clay (CH) and elastic silt (MH) should not be used as backfill. To minimize the



build-up of lateral soil pressures in excess of the recommended design pressures, over-

compaction of the fill behind the wall should be avoided; however, a lesser degree of

compaction may permit excessive post-construction settlements. In order to limit wall pressures

resulting from over-compaction of wall backfill, we recommend that backfill within 5 feet of a wall

be compacted by small, hand-operated compaction equipment to 95 percent of the standard

Proctor maximum dry density. Remaining backfill should be compacted in accordance with the

compaction recommendations provided in the Earthwork section of this report.

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.

APPENDIX A

FIELD EXPLORATION

MAP IS FOR GENERAL LOCATION ONLY

2020 Starita Road, Suite E Charlotte, North Carolina 28206

PH. (704) 509-1777 FAX. (704) 509-1888

A-1

EXB No.SITE VICINITY PLAN

WAVERLY SWIM CLUB POND DAMALBEMARLE ROAD

CHARLOTTE, NORTH CAROLINA

Project Manager:

Drawn by:

Checked by:

Approved by:

SWG

PDM

DJC

DJC

Project No.

Scale:

File Name:

Date:

71135018

N.T.S

A-1 SVP

4/29/2014

APPROXIMATE SITE LOCATION

pdmccloud

Text Box

7/16/2015

LEGEND:

= Approximate Location of Soil Test Borings

= Approximate Location of Hand Auger Borings

BORING LOCATION PLAN

WAVERLY SWIM CLUB POND DAMALBEMARLE ROAD

CHARLOTTE, NORTH CAROLINAA-2

71135018

4/29/2014

SWG

PDM

DJC

DJC

N.T.S.

Project Manager:

Drawn by:

Checked by:

Approved by:

Project No.

Scale:

File Name:

Date:

Exhibit

A-2 BLPDIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR

CONSTRUCTION PURPOSES

W-01

2020 Starita Road, Suite E Charlotte, North Carolina 28206

PH. (704) 509-1777 FAX. (704) 509-1888

W-02

W-03

W-04

W-05

W-HA-01

W-HA-02

W-HA-03

pdmccloud

Text Box

7/16/2015


Responsive ■ Resourceful ■ Reliable Exhibit A-3

Field Exploration Description

The boring locations were laid out on the site by Terracon personnel utilizing a site plan provided

and were measured from available site features. Right angles for the boring locations were

estimated. The locations of the borings should be considered accurate only to the degree

implied by the means and methods used to define them.

The borings were drilled with an ATV-mounted rotary drill rig using hollow stem augers method

to advance the boreholes. Samples of the soil encountered in the borings were obtained using

the split-barrel sampling procedure.

In the split barrel sampling procedure, the number of blows required to advance a standard 2

inch O.D. split barrel sampler the last 12 inches of the typical total 18 inch penetration by

means of a 140 pound hammer with a free fall of 30 inches, is the standard penetration

resistance value (SPT-N). This value is used to estimate the in-situ relative density of

cohesionless soils and consistency of cohesive soils.

An automatic SPT hammer was used to advance the split-barrel sampler in the borings

performed on this site. A significantly greater efficiency is achieved with the automatic

hammer compared to the conventional safety hammer operated with a cathead and rope. This

higher efficiency has an appreciable effect on the SPT-N value.

Hand auger borings were performed in conjunction with Dynamic Cone Penetrometer (DCP)

testing. Samples of the soil encountered in the borings were obtained from the hand auger

cuttings. The DCP test procedure is as follows.

The cone point of the penetrometer is first seated two inches into the bearing materials to embed

the point. The cone point is driven in 1¾-inch increments using a 15-pound weight falling from a

height of 20-inches. The penetrometer reading is the number of blows required to drive the cone

point each increment (blows-per-increment, bpi) and the penetrometer readings are recorded.

The penetrometer reading is similar to the SPT N-value, as defined by ASTM D1586. When

properly evaluated, the penetrometer test results provide an index for estimating soil strength and

relative density.

The samples were tagged for identification, sealed to reduce moisture loss, and taken to our

laboratory for further examination, testing, and classification. Information provided on the

boring logs attached to this report includes soil descriptions, consistency evaluations, boring

depths, sampling intervals, and groundwater conditions. The borings were backfilled with

auger cuttings prior to the drill crew leaving the site.

A field log of each boring was prepared by the drill crew. These logs included visual

classifications of the materials encountered during drilling as well as the driller’s interpretation

of the subsurface conditions between samples. Final boring logs included with this report


Responsive ■ Resourceful ■ Reliable Exhibit A-3

represent the engineer's interpretation of the field logs and include modifications based on

laboratory observation and tests of the samples.

At the completion of each boring, Terracon attempted ground water measurements. The soil

test borings were backfilled immediately after the completion of the exploration, making

subsequent water measurements unobtainable. Water levels tend to fluctuate with seasonal

and climatic variations as well as with some types of construction operations. Therefore, water

may be encountered during construction at depths not indicated during this exploration.

0.3

6.0

18.5

23.5

25.0

8 Ft.:Dry Cave-In Depth

FILL - SANDY LEAN CLAY (CL), tan yellow, soft tomedium stiff, fine to coarse grained sand

FILL - SANDY LEAN CLAY (CL), gray tan, soft, fine tocoarse grained sand

Boring Terminated at 25 Feet

SANDY LEAN CLAY (CL), gray blue, medium stiff, fine tocoarse grained sand (Residual)

40-23-17 58

23

27

702+/-

696.5+/-

684+/-

679+/-

677.5+/-

18

18

10

4

18

18

15

2-2-3N=5

2-1-2N=3

1-1-2N=3

0-1-1N=2

1-1-1N=2

2-3-4N=7

6-10-22N=32

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

LOCATION

GR

AP

HIC

LO

G

DEPTH

See Exhibit A-2

THIS

BO

RIN

G L

OG

IS N

OT

VA

LID

IF S

EP

AR

ATE

D F

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N20

12.G

DT

5/2

4/13

,

CLIENT: Dewberry Charlotte, North Carolina


A-4

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.

WATER LEVEL OBSERVATIONS

PROJECT: Waverly Swim Club Pond Dam

SITE:

Abandonment Method:Borings backfilled with soil cuttings upon completion.

Advancement Method:Hollow Stem Auger

BORING LOG NO. W-01

Notes:

Project No.: 71135018 Exhibit

Boring Completed: 4/24/2013

Drill Rig: CME-550X Driller: Ameridrill

Boring Started: 4/24/2013

Page 1 of 1

Dry at TOB

DR

Y U

NIT

WE

IGH

T (p

cf)

ATTERBERGLIMITS

LL-PL-PI

TES

T TY

PE

STR

AIN

(%)

CO

MP

RE

SS

IVE

STR

EN

GTH

(tsf)

PE

RC

EN

T FI

NE

S

WA

TER

CO

NTE

NT

(%)

SA

MP

LE T

YP

E

WA

TER

LE

VE

LO

BS

ER

VA

TIO

NS

DE

PTH

(ft)

5

10

15

20

25

Approximate Surface Elev.: 702.5 +/-ELEVATION

RE

CO

VE

RY

(%)

FIE

LD T

ES

TR

ES

ULT

S

STRENGTH TEST

TOPSOIL, 3" TOPSOIL/GRASSMAT

SILTY SAND (SM), orange tan to black brown, dense, fineto coarse grained sand (Residual)

0.3

13.5

18.5

23.5

24.3

10.5 Ft.:Wet Cave-In Depth19.5 Ft.:Dry Cave-In Depth

FILL - SANDY LEAN CLAY (CL), brown orange, soft tomedium stiff, fine to medium grained sand

Boring Terminated at 24.3 Feet

SANDY SILT (ML), brown gray to green white, hard, fineto medium grained sand (Residual)

SANDY SILT (ML), tan orange, very stiff, fine to mediumgrained sand (Residual)

PARTIALLY WEATHERED ROCK (PWR), sampled as tanolive sandy silt

40-22-18 60

30

27

702.5+/-

689.5+/-

684.5+/-

679.5+/-

678.5+/-

12

12

18

10

16

18

9

2-2-3N=5

2-2-2N=4

0-2-1N=3

1-1-1N=2

1-14-18N=32

4-9-11N=20

31-50/4"N=50/4"


LOCATION

GR

AP

HIC

LO

G

DEPTH

See Exhibit A-2

THIS

BO

RIN

G L

OG

IS N

OT

VA

LID

IF S

EP

AR

ATE

D F

RO

M O

RIG

INA

L R

EP

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AC

ON

SM

AR

T LO

G-N

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711

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D D

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J T

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12.G

DT

5/2

4/13

,



A-5






SITE:



BORING LOG NO. W-02

Notes:





Page 1 of 1

Dry at TOB

24-Hour

DR

Y U

NIT

WE

IGH

T (p

cf)

ATTERBERGLIMITS

LL-PL-PI

TES

T TY

PE

STR

AIN

(%)

CO

MP

RE

SS

IVE

STR

EN

GTH

(tsf)

PE

RC

EN

T FI

NE

S

WA

TER

CO

NTE

NT

(%)

SA

MP

LE T

YP

E

WA

TER

LE

VE

LO

BS

ER

VA

TIO

NS

DE

PTH

(ft)

5

10

15

20

Approximate Surface Elev.: 703 +/-ELEVATION

RE

CO

VE

RY

(%)

FIE

LD T

ES

TR

ES

ULT

S

STRENGTH TEST

TOPSOIL, 3" TOPSOIL/GRASSMAT

0.2

3.5

6.0

18.5

20.0



SANDY SILT (ML), tan gray, hard, fine to medium grainedsand (Residual)

SANDY SILT (ML), tan olive, hard, fine to medium grainedsand (Residual)

SANDY SILT (ML), tan gray, hard, coarse to fine grainedsand (Residual)

SANDY SILT (ML), gray tan, very stiff, fine to mediumgrained sand (Residual)

704+/-

700.5+/-

698+/-

685.5+/-

684+/-

18

18

12

12

18

18

8-11-20N=31

9-19-26N=45

21-30-21N=51

12-20-21N=41

14-18-19N=37

7-10-13N=23


LOCATION

GR

AP

HIC

LO

G

DEPTH

See Exhibit A-2

THIS

BO

RIN

G L

OG

IS N

OT

VA

LID

IF S

EP

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ATE

D F

RO

M O

RIG

INA

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T.

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ON

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AR

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G-N

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711

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8 - W

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D D

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.GP

J T

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12.G

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4/13

,



A-6






SITE:



BORING LOG NO. W-03

Notes:





Page 1 of 1

Dry at TOB

DR

Y U

NIT

WE

IGH

T (p

cf)

ATTERBERGLIMITS

LL-PL-PI

TES

T TY

PE

STR

AIN

(%)

CO

MP

RE

SS

IVE

STR

EN

GTH

(tsf)

PE

RC

EN

T FI

NE

S

WA

TER

CO

NTE

NT

(%)

SA

MP

LE T

YP

E

WA

TER

LE

VE

LO

BS

ER

VA

TIO

NS

DE

PTH

(ft)

5

10

15

20

Approximate Surface Elev.: 704 +/-ELEVATION

RE

CO

VE

RY

(%)

FIE

LD T

ES

TR

ES

ULT

S

STRENGTH TEST

TOPSOIL, 2" TOPSOIL/PINESTRAW

WA

TER

LE

VE

LO

BS

ER

VA

TIO

NS

DE

PTH

(ft)

5

10

15

20

Approximate Surface Elev.: 703.5 +/-ELEVATION

RE

CO

VE

RY

(%)

FIE

LD T

ES

TR

ES

ULT

S

STRENGTH TEST

0.2

3.5

13.5

18.5

20.0


FILL - SANDY LEAN CLAY (CL), orange brown, stiff, fineto medium grained sand


703.5+/-

700+/-

690+/-

685+/-

683.5+/-

8

18

18

18

18

18

3-5-10N=15

6-9-12N=21

10-18-15N=33

6-6-11N=17

6-7-16N=23

5-9-13N=22


LOCATION

GR

AP

HIC

LO

G

DEPTH

See Exhibit A-2

THIS

BO

RIN

G L

OG

IS N

OT

VA

LID

IF S

EP

AR

ATE

D F

RO

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,



A-7






SITE:



BORING LOG NO. W-04

Notes:





Page 1 of 1

Dry at TOB

DR

Y U

NIT

WE

IGH

T (p

cf)

ATTERBERGLIMITS

LL-PL-PI

TES

T TY

PE

STR

AIN

(%)

CO

MP

RE

SS

IVE

STR

EN

GTH

(tsf)

PE

RC

EN

T FI

NE

S

WA

TER

CO

NTE

NT

(%)

SA

MP

LE T

YP

E

TOPSOIL, 2" TOPSOIL/PINESTRAW

SANDY SILT (ML), olive tan, very stiff to hard, fine tomedium grained sand (Residual)

SANDY SILT (ML), tan olive, very stiff, fine to coarsegrained sand (Residual)

SANDY SILT (ML), olive gray, very stiff, fine to mediumgrained sand (Residual)

0.3

3.0

12.0

18.0

30.0

3" TOPSOILFILL - SILT WITH SAND (ML), brown, soft

FILL - SANDY SILT (ML), gray to brown, soft to medium-stiff

FILL - SILTY SAND (SM), gray, very loose to loose

SILTY SAND (SM), tan, black, to white, medium dense, residuum


2-2-1N=3

1-2-1N=3

1-2-4N=6

2-2-4N=6

0-1-1N=2

2-3-5N=8

5-5-7N=12

8-14-15N=29

701+/-

698.5+/-

689.5+/-

683.5+/-

671.5+/-

8

13

12

12

16

9

10

8

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

LOCATION

DEPTH

GR

AP

HIC

LO

G See Exhibit A-2

THIS

BO

RIN

G L

OG

IS N

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VA

LID

IF S

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D F

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RT

LOG

-NO

WE

LL 7

1135

018

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IM C

LUB

PO

ND

DA

M -

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GP

J T

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PLA

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PD

ATE

3-3

1-14

.GP

J 7

/25/

14

Charlotte, North CarolinaSITE:

Page 1 of 1



2020-E Starita RoadCharlotte, North Carolina

Notes:

Project No.: 71135018

Drill Rig: CME-550X


BORING LOG NO. W-05DewberryCLIENT:Charlotte, North Carolina

Driller: C. Fredrychowski


Exhibit: A-8


See Appendix B for description of laboratoryprocedures and additional data (if any).See Appendix C for explanation of symbols andabbreviations.


FIE

LD T

ES

TR

ES

ULT

S

PE

RC

EN

T FI

NE

S

WA

TER

CO

NTE

NT

(%)

ATTERBERGLIMITS

LL-PL-PI

ELEVATION (Ft.)

Approximate Surface Elev: 701.5 (Ft.) +/- DE

PTH

(Ft.)

5

10

15

20

25

30

SA

MP

LE T

YP

E

WA

TER

LE

VE

LO

BS

ER

VA

TIO

NS

RE

CO

VE

RY

(In.

)

Water Initially ObservedWATER LEVEL OBSERVATIONS

0.3

1.0

3.0

3.6

3" CONCRETEFILL - LEAN CLAY (CL), trace sand, brown to orange

SILTY SAND (SM), gray, redisuum

SILTY SAND (SM), tan to gray

Hand Auger Refusal at 3.6 Feet

703+/-

702+/-

700+/-

699.5+/-

7-8-7

13-19-23

13-25+

20-25+

25+

Stratification lines are approximate. In-situ, the transition may be gradual.

LOCATION

DEPTH

GR

AP

HIC

LO

G See Exhibit A-2

THIS

BO

RIN

G L

OG

IS N

OT

VA

LID

IF S

EP

AR

ATE

D F

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RIG

INA

L R

EP

OR

T.

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MA

RT

LOG

-NO

WE

LL 7

1135

018

- WA

VE

RLY

SW

IM C

LUB

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ND

DA

M -

FIN

AL.

GP

J T

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PLA

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PD

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3-3

1-14

.GP

J 7

/25/

14


Page 1 of 1

Advancement Method:Hand Auger with DCP



Notes:


Drill Rig: N/A


BORING LOG NO. W-HA-01DewberryCLIENT:Charlotte, North Carolina

Driller: P. McCloud/W. Galloway


Exhibit: A-9




ELEVATION (Ft.)

Approximate Surface Elev: 703 (Ft.) +/- DE

PTH

(Ft.)

SA

MP

LE T

YP

E

WA

TER

LE

VE

LO

BS

ER

VA

TIO

NS

DY

NA

MIC

CO

NE

PE

NE

TRO

ME

TER

(DC

P)

BLO

WS

PE

R 1

-3/4

"


0.3

1.0

4.6

8.6

3" CONCRETEFILL - SANDY LEAN CLAY (CL), brown to tan

LEAN CLAY WITH SAND (CL), trace roots, gray, alluvium

SILT WITH SAND (ML), gray to tan, residuum

Hand Auger Refusal on Cobble at 8.6 Feet

703+/-

702+/-

698.5+/-

694.5+/-

5-6-6

3-3-2

2-2-3

1-2-1

2-1-2

6-7-11

10-17-20

18-23-25+

13-15-23


LOCATION

DEPTH

GR

AP

HIC

LO

G See Exhibit A-2

THIS

BO

RIN

G L

OG

IS N

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VA

LID

IF S

EP

AR

ATE

D F

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MA

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LOG

-NO

WE

LL 7

1135

018

- WA

VE

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SW

IM C

LUB

PO

ND

DA

M -

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GP

J T

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PLA

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PD

ATE

3-3

1-14

.GP

J 7

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14


Page 1 of 1




Notes:


Drill Rig: N/A





Exhibit: A-10




ELEVATION (Ft.)


PTH

(Ft.)

5

SA

MP

LE T

YP

E

WA

TER

LE

VE

LO

BS

ER

VA

TIO

NS

DY

NA

MIC

CO

NE

PE

NE

TRO

ME

TER

(DC

P)

BLO

WS

PE

R 1

-3/4

"


0.4

3.6

5.8

10.0

3" CONCRETE

FILL - LEAN CLAY WITH SAND (CL), tan

LEAN CLAY WITH SAND (CL), trace roots, gray, alluvium

SANDY SILT (ML), gray to tan, residuum

Hand Auger Terminated in Residual Soil at 10 Feet

702.5+/-

699.5+/-

697+/-

693+/-

2-2-2

3-3-3

2-2-4

3-3-4

4-3-4

6-6-8

6-6-11

13-21-23

25+

25+


LOCATION

DEPTH

GR

AP

HIC

LO

G See Exhibit A-2

THIS

BO

RIN

G L

OG

IS N

OT

VA

LID

IF S

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AR

ATE

D F

RO

M O

RIG

INA

L R

EP

OR

T.

GE

O S

MA

RT

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-NO

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LL 7

1135

018

- WA

VE

RLY

SW

IM C

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ND

DA

M -

FIN

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J T

EM

PLA

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3-3

1-14

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/25/

14


Page 1 of 1




Notes:


Drill Rig: N/A





Exhibit: A-11




ELEVATION (Ft.)


PTH

(Ft.)

5

10

SA

MP

LE T

YP

E

WA

TER

LE

VE

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BS

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TIO

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NA

MIC

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NE

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(DC

P)

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WS

PE

R 1

-3/4

"


APPENDIX B

LABORATORY TESTING


Responsive ■ Resourceful ■ Reliable Exhibit B-1

Laboratory Testing

Samples retrieved during the field exploration were taken to the laboratory for further

observation by the project geotechnical engineer and were classified in accordance with the

Unified Soil Classification System (USCS) described in Appendix C. At that time, the field

descriptions were confirmed or modified as necessary and an applicable laboratory testing

program was formulated to determine engineering properties of the subsurface materials.

Laboratory tests were conducted on selected soil samples and the test results are presented

on the boring logs. The laboratory test results were used for the geotechnical engineering

analyses, and the development of foundation and earthwork recommendations. Laboratory

tests were performed in general accordance with the applicable ASTM, local or other accepted

standards.

Selected soil samples obtained from the site were tested for the following engineering

properties:

In-situ Water Content

Sieve Analysis

Atterberg Limits

Descriptive classifications of the soils indicated on the boring logs are in accordance with the

enclosed General Notes and the USCS. Also shown are estimated Unified Soil Classification

Symbols. A brief description of this classification system is attached to this report. All

classification was by visual manual procedures. Selected samples were further classified using

the results of Material Finer than No. 200 Sieve and Atterberg limit testing. The Material Finer

than No. 200 Sieve and Atterberg limit test results are provided in the tables below, and are

also provided on the boring logs.

Sample Location,

Depth

In-situ

Moisture

(%)

% Material

Finer than No.

200 Sieve

Liquid

Limit, (%)

Plastic

Limit, (%)

Plasticity

Index, (%)

W-01, 3.5’ – 5.0’ 23 NT 1 NT NT NT

W-01, 6.0’ – 7.5’ 27 58 40 23 17

W-02, 1.0’ – 2.5’ 30 NT NT NT NT

W-02, 8.5’ – 10.0’ 27 60 40 22 18

1. NT = Not Tested

APPENDIX C

SUPPORTING DOCUMENTS

Exhibit C-1

GENERAL NOTES

DRILLING & SAMPLING SYMBOLS:

SS: Split Spoon – 1-3/8" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger

ST: Thin-Walled Tube - 2" O.D., unless otherwise noted PA: Power Auger

RS: Ring Sampler - 2.42" I.D., 3" O.D., unless otherwise noted HA: Hand Auger

DB: Diamond Bit Coring - 4", N, B RB: Rock Bit

BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary

The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SS) the last 12 inches of the total 18-inch

penetration with a 140-pound hammer falling 30 inches is considered the “Standard Penetration” or “N-value”.

WATER LEVEL MEASUREMENT SYMBOLS:

WL: Water Level WS: While Sampling N/E: Not Encountered

WCI

:

Wet Cave in WD: While Drilling

DCI

:

Dry Cave in BCR: Before Casing Removal

AB: After Boring ACR: After Casing Removal

Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater. In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations.

DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils

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

CONSISTENCY OF FINE-GRAINED SOILS RELATIVE DENSITY OF COARSE-GRAINED SOILS

Unconfined

Compressive

Strength, Qu, psf

Standard Penetration or N-

value (SS) Blows/Ft.

Consistency Standard Penetration

or N-value (SS) Blows/Ft.

Relative Density

< 500 0 – 1 Very Soft 0 – 3 Very Loose

500 – 1,000 2 – 4 Soft 4 – 9 Loose

1,001 – 2,000 4 – 8 Medium Stiff 10 – 29 Medium Dense

2,001 – 4,000 8 – 15 Stiff 30 – 49 Dense

4,001 – 8,000 15 – 30 Very Stiff > 50 Very Dense

8,000+ > 30 Hard

RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY

Descriptive Term(s) of other

Constituents

Percent of

Dry Weight

Major Component

of Sample Particle Size

Trace < 15 Boulders Over 12 in. (300mm)

With 15 – 29 Cobbles 12 in. to 3 in. (300mm to 75 mm)

Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm)

Sand #4 to #200 sieve (4.75mm to

0.075mm)

Silt or Clay Passing #200 Sieve (0.075mm)

RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION

Descriptive Term(s) of other

Constituents

Percent of

Dry Weight Term

Plasticity

Index

Trace < 5 Non-plastic 0

With 5 – 12 Low 1 – 10

Modifiers > 12 Medium 11 – 30

High > 30

Exhibit C-2

UNIFIED SOIL CLASSIFICATION SYSTEM

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

Soil Classification

Group

Symb

ol

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.

final geotechnical engineering report

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