SW3191104_190425.20 Providence Road South, 1425 Geotech Report 5-13-19[1]_2/14/2020

_. - -Atl.
HYDROENGINEE
Report of Subsurface Exploration
and Geotechnical Engineering Evaluation
1425 Providence Road South
Waxhaw, North Carolina
Geo-Hydro Project Number 190425.20
Prepared for GS Development, LLC
May 13, 2019
1

Mr. Elias Garcia
GS Development, LLC
18008 Mollypop Lane
Cornelius, North Carolina 28031
Dear Mr. Garcia:
May 13, 2019
Report of Subsurface Exploration and
Geotechnical Engineering Evaluation
1425 Providence Road South
Waxhaw, North Carolina
Geo-Hydro Project Number 190425.20
Geo-Hydro Engineers, Inc. has completed the authorized subsurface exploration and geotechnical
engineering evaluation for the above referenced project. The scope of services for this project was outlined
in our proposal number 23005.23 dated April 29, 2019.
PROJECT INFORMATION
Planning is underway for development
of an approximate 11,500 square -foot,
1-story daycare to be located at 1425
Providence Road South in Waxhaw,
North Carolina. The project site
appears to have been previously
cleared but has not been rough graded.
We understand the property formerly
contained a residential structure which
was previously demolished.
A proposed grading plan was not
provided, however, topography at the
site slopes down gradually from west
to east. Site work will consist of
asphalt parking and drive lanes, a;
retaining wall, and an underground
stormwater management system. The retaining wall is expected to range in height from 4 to 12 feet and
will be constructed along the east side of the site to achieve design grades
Anticipated foundation loads for the structure and a proposed grading plan were not available at the time
of this report. Based on the existing topography, we expect site grading to consist of less than 5 feet of mass
excavation or structural fill placement. Based on our experience, we have assumed that individual column
loads will be no greater than about 50 kips and that wall loads will be less than about 3 kips per lineal foot.
If actual foundation loads are determined to be greater than our assumptions, please allow us to review
and revise our recommendations as appropriate.
2748 Interstate Street, Suite A Charlotte, North Carolina 28208 HYDRO
o:704.837.7174 . f: 336.553.0872 www.geohydro.com ENGINEERS

1425 Providence Road South • Waxhaw, North Carolina
Project Number 190425.20
EXPLORATORY PROCEDURES
The subsurface exploration consisted of 10 soil test borings performed at the approximate locations shown
on Figures 2 and 3, in the Appendix. The test borings were located in the field by Geo-Hydro using a
Garmin Etrex 64 GPS unit with preloaded coordinates obtained from Google Earth, and by measuring
angles and distances from existing site features. In general, the boring locations should be considered
approximate.
Standard penetration testing, as provided for in ASTM D1586, was performed at select depth intervals in
the soil test borings. Soil samples obtained from the drilling operation were examined and classified in
general accordance with ASTM D2488 (Visual -Manual Procedure for Description of Soils). Soil
classifications include the use of the Unified Soil Classification System described in ASTM D2487
(Classification of Soils for Engineering Purposes). The soil classifications also include our evaluation of
the geologic origin of the soils. Evaluations of geologic origin are based on our experience and
interpretation and may be subject to some degree of error.
Descriptions of the soils encountered, groundwater conditions, standard penetration resistances, and other
pertinent information are provided in the test boring records included in the Appendix.
REGIONAL GEOLOGY
The project site is located in the Charlotte Belt of the Piedmont Geologic Province of North Carolina. Soils
in this area have been formed by the in -place weathering of the underlying crystalline rock, which accounts
for their classification as "residual' soils. Residual soils near the ground surface, which have experienced
advanced weathering, frequently consist of red brown clayey silt (ML) or silty clay (CL). The thickness of
this surficial clayey zone may range up to roughly 6 feet. For various reasons, such as erosion or local
variation of mineralization, the upper clayey zone is not always present.
With increased depth, the soil becomes less weathered, coarser grained, and the structural character of the
underlying parent rock becomes more evident. These residual soils are typically classified as sandy
micaceous silt (ML) or silty micaceous sand (SM). With a further increase in depth, the soils eventually
become quite hard and take on an increasing resemblance to the underlying parent rock. When these
materials have a standard penetration resistance of 100 blows per foot or greater, they are referred to as
partially weathered rock. The transition from soil to partially weathered rock is usually a gradual one, and
may occur at a wide range of depths. Lenses or layers of partially weathered rock are not unusual in the soil
profile.
Partially weathered rock represents the zone of transition between the soil and the indurated metamorphic
rocks from which the soils are derived. The subsurface profile is, in fact, a history of the weathering process
which the crystalline rock has undergone. The degree of weathering is most advanced at the ground surface,
where fine grained soil may be present. And, the weathering process is in its early stages immediately above
the surface of relatively sound rock, where partially weathered rock may be found.
The thickness of the zone of partially weathered rock and the depth to the rock surface have both been
found to vary considerably over relatively short distances. The depth to the rock surface may frequently
range from the ground surface to 80 feet or more. The thickness of partially weathered rock, which overlies
the rock surface, may vary from only a few inches to as much as 40 feet or more.
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1425 Providence Road South • Waxhaw, North Carolina
Project Number 190425.20
SOIL TEST BORING SUMMARY
Starting at the ground surface, all of the borings encountered between 4 and 12 inches of topsoil. The
thickness of surface materials at the site should be expected to vary, and measurements necessary for
detailed quantity estimation were not performed for this report. For planning purposes, we suggest
considering a topsoil thickness of about 8 inches to account for existing vegetation and shallow roots.
Beneath the topsoil, all of the borings encountered residual soils typical of the Charlotte Belt. The residual
soils were generally classified as silty sand, clayey sand, sandy silt, clayey silt, or silty clay. Standard
penetration resistances in the residual soils ranged from 3 to 41 blows per foot.
Partially weathered rock (PWR) was encountered in boring B-3 at a depth of about 12 feet. Partially
weathered rock is defined as residual material having a standard penetration resistance greater than 100
blows per foot.
At the time of drilling, groundwater was not encountered in any borings. For safety reasons, the boreholes
were backfilled with soil cuttings after the initial groundwater check except for P-2. After 24-hours,
groundwater was encountered within boring P-2 at a depth of 9 feet. It should be noted that groundwater
levels will fluctuate depending on yearly and seasonal rainfall variations and other factors and may rise in
the future.
For more detailed descriptions of subsurface conditions, please refer to the test boring records included in
the Appendix.
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1425 Providence Road South • Waxhaw, North Carolina
Project Number 190425.20
EVALUATIONS AND RECOMMENDATIONS
The following evaluations and recommendations are based on the information available on the proposed
construction, the data obtained from the test borings, and our experience with soils and subsurface
conditions similar to those encountered at this site. Because the test borings represent a statistically small
sampling of subsurface conditions, it is possible that conditions may be encountered during construction
that are substantially different from those indicated by the test borings. In these instances, adjustments to
the design and construction may be necessary.
Geotechnical Considerations
The following geotechnical characteristics of the site should be considered for planning and design:
• The materials encountered in the borings indicate generally favorable excavation conditions within
anticipated excavation depths. Residual soils should be readily removable using conventional soil
excavation equipment such as loaders and backhoes. Partially weathered rock was encountered in
boring B-3 at a depth of about 12 feet and it is possible that hard materials will be encountered during
mass excavation in this area or at other locations intermediate of our boring locations. Partially
weathered rock will require large backhoes capable of ripping to facilitate excavation.
• It is our understanding that a retaining wall will be installed along the east side of the site to achieve
design grades. If the wall will be a mechanically stabilized earth (MSE) wall, the backfill material
within the reinforced zone must meet specific gradation parameters. Fine-grained soils, such as sandy
silts and sandy clays that were encountered within many of the test borings, will usually not be
acceptable for use within the reinforced zone unless specifically designed for. Considerations should
be made to obtain suitable material from an acceptable offsite borrow source and/or to perform
laboratory testing of site soils and results submitted to the MSE wall designer for review.
• At the time of drilling, groundwater was not encountered in any of the borings. After 24-hours,
groundwater was encountered within boring P-2 at a depth of 9 feet. Groundwater is not expected to be
a concern for shallow foundation construction but may be a concern for deeper utility installations.
• For Seasonally High -Water Table (SHWT) evaluation, a 24-hour groundwater reading was performed
in boring P-2. Groundwater was encountered at a depth of 9 feet. Based on our review of the
groundwater and soil conditions at boring P-2, we estimate the SHWT elevation to be located at 9 feet
below the existing ground surface at that location. In accordance with the NC DEQ Stormwater Design
Manual, the bottom of planned stormwater management facilities should be at least 2 feet above the
SHWT elevation.
• Contingent upon proper site preparation and thorough evaluation of the foundation excavations, it is
our opinion that the proposed building can be supported using conventional shallow foundations and
concrete slab -on -grade floors. We recommend an allowable gross bearing pressure of 3,000 psf for
design purposes.
• Based on the results of the test borings and following the calculation procedure in the 2012 North
Carolina State Building Code, the Site Class for the project is D.
The following sections provide recommendations regarding these issues and other geotechnical aspects of
the project.
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1425 Providence Road South • Waxhaw, North Carolina
Project Number 190425.20
Existing Fill Materials
Existing fill materials were not encountered in any of the borings; however, there are several important
facts that should be considered regarding existing fill materials and the limitations of subsurface
exploration.
• The quality of existing fill materials can be highly variable, and test borings are often not able to detect
all of the zones or layers of poor quality fill materials.
• Layers of poor quality fill materials that are less than about 2.5 to 5 feet thick may often remain
undetected by soil test borings due to the discrete -interval sampling method used in this exploration.
• The interface between existing fill materials and the original ground surface may include a layer of
organic material that was not properly stripped off during the original grading. Depending on its
relationship to the foundation and floor slab bearing surfaces, an organic layer might adversely affect
support of footings and floor slabs. If such organic layers are encountered during construction, it may
be necessary to "chase out" the organic layer by excavating the layer along with overlying soils.
• The construction budget should include funds for management of poor quality existing fill materials.
• Subsurface exploration is simply not capable of disclosing all conditions that may require remediation.
During site preparation, burn pits or trash pits may be encountered. On sites located in or near
developed areas, this is not an unusual occurrence. All too frequently such buried material occurs in
isolated areas which are not detected by the soil test borings. Any buried debris or trash found during
the construction operation should be thoroughly excavated and removed from the site.
General Site Preparation
Trees, shrubs, grass, topsoil, roots, and other deleterious materials, including old foundations or septic drain
field if encountered, should be removed from the proposed construction areas. All existing utilities should
be excavated and removed unless they are to be incorporated into the new construction. Additionally, site
grubbing and stripping should be performed only during dry weather conditions. Operation of heavy
equipment on the site during wet conditions could result in excessive subgrade degradation. All excavations
resulting from demolition of above- or below -grade structures or the rerouting of underground utilities
should be backfilled in accordance with the Structural Fill section of this report.
We recommend that areas to receive structural fill be proofrolled prior to placement of structural fill. Areas
of proposed excavation should be proofrolled after rough finished subgrade is achieved. Proofrolling should
be performed with multiple passes in at least two directions using a fully loaded tandem axle dump truck
weighing at least 18 tons. If low consistency soils are encountered that cannot be adequately densified in
place, such soils should be removed and replaced with well compacted fill material placed in accordance
with the Structural Fill section of this report. Proofrolling should be observed by Geo-Hydro to determine
if remedial measures are necessary.
For budgeting purposes, we suggest considering that approximately 25 percent of the aggregate building
and pavement footprint areas will require undercutting and replacement extending to a depth of 2 feet.
The suggested stabilization approach is intended only as a tool to estimate a cost associated with general
ground stabilization. The need for, extent of, location, and optimal method of treating unstable subgrades
should be determined by Geo-Hydro at the time of construction based on actual site conditions. The extent
and cost ofground stabilization may exceed the suggested budgetary estimate.
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1425 Providence Road South • Waxhaw, North Carolina
Project Number 190425.20
During site preparation, burn pits or trash pits may be encountered. On sites located in or near developed
areas, this is not an unusual occurrence. All too frequently such buried material occurs in isolated areas
which are not detected by the soil test borings. Any buried debris or trash found during the construction
operation should be thoroughly excavated and removed from the site.
Excavation Characteristics
In general, residual soils within the anticipated depth of foundations and underground utilities should be
readily removable using conventional soil excavation equipment such as loaders and backhoes. Partially
weathered rock was encountered in boring B-3 at a depth of about 12 feet and it is possible that hard
materials will be encountered during mass excavation in this area or at other locations intermediate of our
boring locations. Partially weathered rock will require large backhoes capable of ripping to facilitate
excavation.
For construction bidding and field verification purposes it is common to provide a verifable definition of
rock in the project specifications. The following are typical definitions of mass rock and trench rock:
Mass Rock: Material which cannot be excavated with a single -tooth ripper drawn by a crawler tractor
having a minimum draw bar pull rated at 56,000 pounds (Caterpillar D-8K or equivalent), and
occupying an original volume of at least one cubic yard.
• Trench Rock: Material occupying an original volume of at least one-half cubic yard which cannot be
excavated with a hydraulic excavator having a minimum flywheel power rating of 123 kW (165 hp);
such as a Caterpillar 322C L, John Deere 230C LC, or a Komatsu PC220LC-7; equipped with a short
tip radius bucket not wider than 42 inches.
The foregoing definitions are based on large equipment typically utilized for mass grading. Subsequent
excavations for building foundations, retaining walls, and underground utilities are often performed with
smaller equipment such as rubber -tired backhoe/loaders or even mini -excavators. Contractors will often
request additional payment for mobilizing larger equipment than that which was anticipated during
preparation of their construction bid. The amount of additional compensation, if any, and the minimum
equipment size necessary to qualify for any additional compensation should be defined before the start of
construction.
Reuse of Excavated Materials
Based on the results of test borings and our observations, some of the residual soils and some of the existing
fill materials at the site appear to be suitable for reuse as structural fill. Geo-Hydro should observe the
excavation of existing fill materials to evaluate their suitability for reuse. Soft, unstable fill soils free of
deleterious materials may be reusable after routine moisture adjustment. Highly organic soils and debris -
laden soils will not be suitable for reuse. Routine adjustment of moisture content will be necessary to allow
proper placement and compaction.
It is important to establish as part of the construction contract whether soils having elevated moisture
content will be considered suitable for reuse. We often find this issue to be a point of contention and a
source of delays and change orders. From a technical standpoint, soils with moisture contents wet of
optimum as determined by the standard Proctor test (ASTM D698) can be reused provided that the moisture
is properly adjusted to within the workable range. From a practical standpoint, wet soils can be very difficult
to dry in small or congested sites and such difficulties should be considered during planning and budgeting.
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1425 Providence Road South • Waxhaw, North Carolina
Project Number 190425.20
A clear understanding by the general contractor and grading subcontractor regarding the reuse of excavated
soils will be important to avoid delays and unexpected cost overruns.
Structural Fill
Materials selected for use as structural fill should be free of organic debris, waste construction debris, and
other deleterious materials. The material should not contain rocks having a diameter over 4 inches. It is our
opinion that the following soils represented by their USCS group symbols will typically be suitable for use
as structural fill and are usually found in abundance in the Piedmont: (SM), (ML), (CL), (SC). The
following soil types are also suitable but are less abundant in the Piedmont: (SW), (SP), (SP-SM), and
(SP-SC). If encountered, soils classified as (MI-1) or (CH) may be used in non-structural fill areas or in
deeper fill areas greater than 2 feet below the finished subgrade elevation. The following soil types are
typically considered unsuitable: (OL), (OH), and (Pt).
If encountered, highly plastic silt or clay, (MH) or (CH) soils, should be used with extreme caution. Such
soils will require protection against desiccation or inundation during the construction process. Soils which
have a liquid limit greater than 60 and a plasticity index greater than 35 should be blended with less plastic
materials to result in lower Atterberg limits if used within the upper 3 feet beneath finished surfaces.
Laboratory Proctor compaction tests and classification tests should be performed on representative samples
obtained from the proposed borrow material to provide data necessary to determine acceptability and for
quality control. The moisture content of suitable borrow soils should generally be no more than 3 percentage
points below or above optimum at the time of compaction. Tighter moisture limits may be necessary with
certain soils.
Suitable fill material should be placed in thin lifts. Lift thickness depends on the type of compaction
equipment, but a maximum loose -lift thickness of 8 inches is generally recommended. The soil should be
compacted by a self-propelled sheepsfoot roller. Within small excavations such as in utility trenches, around
manholes, above foundations, or behind retaining walls, we recommend the use of "Wacker packers" or
"Rammax" compactors to achieve the specified compaction. Loose lift thicknesses of 4 to 6 inches are
recommended in small area fills.
We recommend that structural fill be compacted to at least 95 percent of the standard Proctor maximum
dry density (ASTM D698). The upper 12 inches of floor slab subgrade soils should be compacted to at least
98 percent of the standard Proctor maximum dry density. Additionally, the maximum dry density of
structural fill should be no less than 90 pcf. Following North Carolina DOT guidelines, the upper 8 inches
of pavement subgrade soils should be compacted to at least 100 percent of the maximum dry density as
determined by AASHTO T99. Geo-Hydro should perform density tests during fill placement.
Earth Slopes
Temporary construction slopes should be designed in strict compliance with current OSHA regulations.
The soil test borings indicate that most soils at the site are Type B (residuum) as defined in 29 CFR 1926
Subpart P. This dictates that temporary construction slopes be no steeper than 1H:1V for Type B
soils for excavation depths of 20 feet or less. Excavations should be closely observed daily by the
contractor's "competent person" for signs of mass movement: tension cracks near the crest, bulging at the
toe of the slope, etc. The responsibility for excavation safety and stability of construction slopes should lie
solely with the contractor.
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1425 Providence Road South • Waxhaw, North Carolina
Project Number 190425.20
We recommend that extreme caution be observed in trench excavations. Several cases of loss of life due to
trench collapses in North Carolina point out the lack of attention given to excavation safety on some
projects. We recommend that applicable local and federal regulations regarding temporary slopes, and
shoring and bracing of trench excavations be closely followed.
Formal analysis of slope stability was beyond the scope of work for this project. Based on our experience,
permanent cut or fill slopes should be no steeper than 2H:1 V to maintain long term stability and to provide
ease of maintenance. The crest or toe of cut or fill slopes should be no closer than 10 feet to any foundation.
The crest or toe should be no closer than 5 feet to the edge of any pavements. Erosion protection of slopes
during construction and during establishment of vegetation should be considered an essential part of
construction.
Earth Pressure
Three earth pressure conditions are generally considered for retaining wall design: "at rest", "active", and
"passive" stress conditions. Retaining walls which are rigidly restrained at the top and will be essentially
unable to rotate under the action of earth pressure (such loading dock walls) should be designed for "at rest"
conditions. Retaining walls which can move outward at the top as much as 0.5 percent of the wall height
(such as free-standing walls) should be designed for "active" conditions. For the evaluation of the resistance
of soil to lateral loads the "passive" earth pressure must be calculated. It should be noted that full
development of passive pressure requires deflections toward the soil mass on the order of 1.0 percent to 4.0
percent of total wall height.
Earth pressure may be evaluated using the following equation:
pn = K (DWZ + qs) + W(Z-d)
where: pn = horizontal earth pressure at any depth below the ground surface (Z).
W = unit weight of water
Z = depth to any point below the ground surface
d = depth to groundwater surface
DW = partially saturated unit weight of the soil backfill (depending on borrow sources). The
wet unit weight of most residual soils may be expected to range from approximately
115 to 125 pcf. Below the groundwater level, DW must be the buoyant weight.
q, = uniform surcharge load (add equivalent uniform surcharge to account for construction
equipment loads)
K = earth pressure coefficient as follows:
Earth Pressure Condition Coefficient
At Rest (Ko) 0.56
Active (Ka) 0.39
Passive (Kp) 2.56
The groundwater term, Ww(Z-d), should be used if no drainage system is incorporated behind retaining
walls. If a drainage system is included which will not allow the development of any water pressure behind
the wall, then the groundwater term may be omitted. The development of excessive water pressure is a
common cause of retaining wall failures. Drainage systems should be carefully designed to ensure that long
term permanent drainage is accomplished.
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1425 Providence Road South • Waxhaw, North Carolina
Project Number 190425.20
The design recommendations are based on the following assumptions:
Horizontal backfill
95 percent standard Proctor compactive effort on backfill (ASTM D698)
No safety factor is included
For convenience, equivalent fluid densities are frequently used for the calculation of lateral earth pressures.
For "at rest" stress conditions, an equivalent fluid density of 67 pcf may be used. For the "active" state of
stress an equivalent fluid density of 47 pcf may be used. These equivalent fluid densities are based on the
assumptions that drainage behind the retaining wall will allow no development of hydrostatic pressure; that
native sandy silts or silty sands will be used as backfill; that the backfill soils will be compacted to 95
percent of standard Proctor maximum dry density; that backfill will be horizontal; and that no surcharge
loads will be applied.
For analysis of sliding resistance of the base of a cast -in -place concrete retaining wall, the coefficient of
friction may be taken as 0.35 for the soils at the project site. This is an ultimate value, and an adequate
factor of safety should be used in design. The force which resists base sliding is calculated by multiplying
the normal force on the base by the coefficient of friction. Full development of the frictional force could
require deflection of the base of roughly 0.1 to 0.3 inches.
Foundation Design
After general site preparation and site grading have been completed in accordance with the
recommendations of this report, it is our opinion that the proposed building can be supported using
conventional shallow foundations. We recommend an allowable gross bearing pressure of 3,000 psf for
foundation design. In addition, we recommend a minimum width of 24 inches for column footings and 18
inches for continuous wall footings to prevent general bearing capacity failure. Footings should bear at a
minimum depth of 18 inches below the prevailing exterior ground surface elevation to avoid potential
problems due to frost heave.
The recommended bearing pressure is based on an assumed maximum column load of 100 kips and a
maximum wall load of 3 kips per lineal foot, as well as an estimated maximum total foundation settlement
no greater than approximately 1 inch, with anticipated differential settlement between adjacent columns not
exceeding about '/2 inch. If the architect or structural engineer determine that the maximum anticipated
loads exceed our assumed values, or if it is determined that the estimated total or differential settlement
cannot be accommodated by the proposed structure, please contact us.
Foundation bearing surface evaluations should be performed in all footing excavations prior to placement
of reinforcing steel. These evaluations should be performed by Geo-Hydro to confirm that the design
allowable soil bearing pressure is available. Foundation bearing surface evaluations should be performed
using a combination of visual observation, hand augering, and portable dynamic cone penetrometer testing
(ASTM STP-399).
Because of natural variation, it is possible that some of the soils at the project site may have an allowable
bearing pressure less than the recommended design value. Therefore, foundation bearing surface
evaluations will be critical to aid in the identification and remediation of these situations.
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1425 Providence Road South • Waxhaw, North Carolina
Project Number 190425.20
Remedial measures should be based on actual field conditions. However, in most cases we expect the use
of the stone replacement technique to be the primary remedial measure. Stone replacement involves the
removal of soft or loose soils, and replacement with densified No. 57 size aggregate meeting North Carolina
Department of Transportation specifications for gradation. Stone replacement is generally performed to
depths ranging from a few inches to as much as 2 times the footing width, depending on the actual
conditions.
For budgeting purposes, we suggest considering a contingency to treat approximately 20 percent of the
foundation excavations using stone replacement extending to a depth of 3 feet below bearing elevation. The
actual quantity of stone replacement will be different and may exceed the suggested estimate.
Seismic Design
Based on the results of the soil test borings, and following the calculation procedure in the 2018 North
Carolina Building Code, a Site Class D should be used for seismic design. The mapped and design spectral
response accelerations are as follows: Ss=0.268, S1=0.110, SDs=0.283, SD,=0.173.
Based on the information obtained from the soil test borings, it is our opinion that the potential for
liquefaction of the residual soils at the site due to earthquake activity is relatively low.
Floor Slab Subgrade Preparation
The soil subgrade in the area of concrete slab -on -grade support is often disturbed during foundation
excavation, plumbing installation, and superstructure construction. We recommend that the floor slab
subgrade be evaluated by Geo-Hydro immediately prior to beginning floor slab construction. If low
consistency soils are encountered that cannot be adequately densified in place, such soils should be removed
and replaced with well -compacted fill material placed in accordance with the Structural Fill section of this
report or with well -compacted aggregate base course (ABC).
Assuming that the top 12 inches of floor slab subgrade soils are compacted to at least 98 percent of the
standard Proctor maximum dry density, we recommend that a modulus of subgrade reaction of 120 pci be
used for design.
Moisture Control for Concrete Slabs
To prevent the capillary rise of groundwater from adversely affecting the concrete slab -on -grade floor, we
recommend that slab -on -grade floors be underlain by a minimum 4-inch thickness of open -graded stone.
Use of 957 crushed stone meeting North Carolina DOT specifications for gradation is suggested. The stone
must be covered by a vapor retarder. We suggest polyethylene sheeting at least 10 mils thick as a minimum
vapor retarder.
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1425 Providence Road South • Waxhaw, North Carolina
Project Number 190425.20
Flexible Pavement Design
Based on our experience with similar projects, assuming standard pavement design parameters, and
contingent upon proper pavement subgrade preparation, we recommend the following pavement sections:
iaht-Duty Pavemer' assenaer Vehicles 0
Asphaltic Concrete S9.513 Superpave 2
Aggregate Base Course (ABC) 6
Subarade compacted to at least 100% of AASHTO T99 8
Pavement (Main Drive Lanes and Truck Traffic Areas
Asphaltic Concrete S9.513 Superpave 1.5
Asphaltic Concrete 119.00 Superpave 2.5
Aggregate Base Course (ABC) 8
Subarade compacted to at least 100% of AASHTO T99 8
A concrete thickness of 7 inches is recommended for the approach and collection zone in front of the
dumpster and in truck turn -around areas. Please refer to the Concrete Pavement section of this report for
concrete pavement recommendations.
The top 8 inches of pavement subgrade soils should be compacted to at least 100 percent of the maximum
dry density as determined by AASHTO T99. Scarification and moisture adjustment will likely be required
to achieve the recommended subgrade compaction level. Allowances for pavement subgrade preparation
should be considered for budgeting and scheduling. ABC should be compacted to at least 100 percent of
the maximum dry density as determined by AASHTO T180.
All pavement construction should be performed in general accordance with North Carolina DOT
specifications. Proper subgrade compaction, adherence to North Carolina DOT specifications, and
compliance with project plans and specifications, will be critical to the performance of the constructed
pavement.
Concrete Pavement
We recommend a concrete thickness of 7 inches for truck turn -around areas and the approach and collection
zone in front of the dumpster. A 600-psi flexural strength concrete mix (approximately 4,500 psi
compressive) with 4 to 6 percent air entrainment should be used. The concrete pavement must be underlain
by no less than 5 inches of compacted aggregate base course (ABC). ABC should be compacted to at least
100 percent of the maximum dry density as determined by AASHTO T180. The top 8 inches of soil
subgrade should be compacted to at least 100 percent of the maximum dry density as determined by
AASHTO T99.
The concrete pavement may be designed as a "plain concrete pavement" with no reinforcing steel or
reinforcing steel may be used at joints. Construction joints and other design details should be in accordance
with guidelines provided by the Portland Cement Association and the American Concrete Institute.
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1425 Providence Road South • Waxhaw, North Carolina
Project Number 190425.20
In general, all pavement construction should be in accordance with North Carolina DOT specifications.
Proper subgrade compaction, adherence to North Carolina DOT specifications, and compliance with project
plans and specifications will be critical to the performance of the constructed pavement.
Pavement Design Limitations
The pavement sections discussed above are based on our experience with facilities similar to the one
planned for this project. After traffic information has been developed, we recommend that you allow us to
review the traffic data and revise our recommendations as necessary.
We appreciate the opportunity to serve as your geotechnical consultant for this project, and are prepared to
provide any additional services you may require. If you have any questions concerning this report or any
of our services, please call us.
Sincerely,
GEO-HYDRO ENGINEERS, INC.
NC Registered Engineering Firm C-3649�
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TMB/GDS/190425.20 Providence Road South, 1425 Geotech Report 5-9-19
M ay 13, 2019 112 HYDRO

APPENDIX
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FIGURES
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ENGINEERS
0.25 0.5 1 1.
Approximate Scale, Miles
1425 Providence Road South
Figure 1: Site Location Plan Waxhaw, North Carolina
Geo-Hydro Project 190425.20

ROPOSED SEGMENTAL
RETAINING WALL -'4' TO
8' IN HEIGHT
PROPOSED 12'x10'
OPSTER ENCLOSURE /
WITH MASONRY I
SCREEN WALL /
1
:..........
PROPOSED BLACK VINYL PROPOSED SEGMENTAL RETAINING - PROPOSED 10' TEMPORARY
CHAINLINK FENCE. WALL -4' TO 12' IN HEIGHT. CONSTRUCTION EASEMENT
10' BUFFER R-2
L.
PROPONCRETE
I� DUMPST R PAD. i
PROPOSED T ///
UNDERGROUND
STORMWATER i
iEATMENT AREA /f/�
O
11,
'
9
O
PROPOSEDS
n n
O
COMPACT SPACES
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1 '
1
P-1
/
1 W
�4
1 irl
1 I
^RIW
•
1
---R/W----R/W—
�__R-
DOST.
OHP-f
R/W
/
1
1
Not to Scale
24.0'
(TYP.)
FUTURE 25'
SETBACK_
9
26.0
PROP. RIW
HP =F-/W
R_EARYARD-
PROPOSED
PLAYGROUND AREA "
7,500± SF
— 142.1'
19.5' II
6.0' .d"(
G 9
PROPOSEq DAYCARE
11,500± SF - 141MRYBUILDING
F.F. 3.25 _
Zoning: O f
PRELIMINARY PLAN - NOT FOR CONSTRUCTION
APPROXIMATE LOCATION OF MAILBOX.
COORDINATE FINAL LOCATION WITH USPS.
•
0'
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cn
in
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ID
of
HYDRO
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1
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1
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1 ZO
OWNER
OWNER
1 OWNER
1 CIVIL EN
BLOC DE
I ZONING
1 JURISDI,
W — — - - R - - / — PARCEL
1 SETBAC
APPROXIMATE LOCATION OF 1 FRONT'.
MONUMENT SIGN. FINAL LOCATION TBD. I slDe.
REAR
—R/'W" " P =R QdP=-R lw=OJiR —R7'Vr-0HP --�{ -0 p=_R-/yr-OHP9F2_=f2/iMQHP-t,-- SCREEN
I FRONT
SIDE
REAR
EPDDITIR
PROVIDENCE ROAD SOUTH (NC HWY. 16)
BUFFER
FRONT
SIDE
REAR
IMPERVI
REFER T
PARKING
REQUIRE
PROVIDE
1425 Providence Road South
LEGEND: -$� Soil Test Boring Figure 2: Boring Location Plan Waxhaw, North Carolina
Geo-Hydro Project Number 190425.20

} 1 ■
Not to Scale
LEGEND: -$� Soil Test Boring
Figure 3: Boring Location Plan
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1425 Providence Road South
Waxhaw, North Carolina
Geo-Hydro Project Number 190425.20

TEST BORING RECORDS
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Symbols and Nomenclature
Symbols
Thin -walled tube (TWT) sample recovered
mThin -walled tube (TWT) sample not recovered
• Standard penetration resistance (ASTM D1586)
50/2" Number of blows (50) to drive the split -spoon a number of inches (2)
65% Percentage of rock core recovered
RQD Rock quality designation - % of recovered core sample which is 4 or more inches long
GW Groundwater
V Water level at least 24 hours after drilling
0 Water level one hour or less after drilling
ALLUV Alluvium
TOP Topsoil
PM
Pavement Materials
CONC
Concrete
FILL
Fill Material
RES
Residual Soil
PWR
Partially Weathered Rock
SPT
Standard Penetration Testing
Penetration Resistance Results
Number of Blows, N
Approximate
Relative Density
Sands 0-4
very loose
5-10
loose
11-20
firm
21-30
very firm
31-50
dense
Over 50
very dense
Approximate
Number of Blows, N
Consistency
Silts and 0-1
very soft
Clays 2-4
soft
5-8
firm
9-15
stiff
16-30
very stiff
31-50
hard
Over 50
very hard
Drilling Procedures
Soil sampling and standard penetration testing performed in accordance with ASTM D 1586. The standard penetration resistance is the number
of blows of a 140-pound hammer falling 30 inches to drive a 2-inch O.D., 1.4-inch I.D. split -spoon sampler one foot. Rock coring is performed
in accordance with ASTM D 2113. Thin -walled tube sampling is performed in accordance with ASTM D 1587.
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LMain/Geo/Misc/Symbols&Nomenclature ENGINEERS

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B-1 Test Boring Record HYDRO
Project: 1425 Providence Road South
Project No: 190425.20
Location: Waxhaw, North Carolina
Date: 5/4/19
Method: HSA-ASTM D1586
GWT at Drilling: Not Encountered
G.S. Elev:
Driller: EDPS (Auto Hammer)
GWT at 24 hrs: N/A (Boring Backfilled)
Logged By: TMB
t
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Standard Penetration Test
LL
E
Description
N
(Blows/Foot)
w
0
cn
0 10 20 30 40 50 60 70 80 90 100
Topsoil (Approximately 6 inches)
Stiff to very stiff tan fine sandy silt (ML)
(RESIDUUM)
11
5
14
18
10
13
15
12
Boring Terminated at 15 feet
20
25
Remarks:

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B-2 Test Boring Record HYDRO
Project: 1425 Providence Road South
Project No: 190425.20
Location: Waxhaw, North Carolina
Date: 5/4/19
Method: HSA-ASTM D1586
GWT at Drilling: Not Encountered
G.S. Elev:
Driller: EDPS (Auto Hammer)
GWT at 24 hrs: N/A (Boring Backfilled)
Logged By: TMB
t
o
Standard Penetration Test
LL
E
Description
N
(Blows/Foot)
w
0
cn
0 10 20 30 40 50 60 70 80 90 100
Topsoil (Approximately 12 inches)
Very loose dark gray and tan silty fine sand
(SM) with root fragments (RESIDUUM)
3
Stiff tan clayey silt (ML)
5
14
Very firm to dense tan silty fine to coarse
sand (SM)
31
10
36
15
Boring Terminated at 15 feet 30
20
25
Remarks:

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B-3 Test Boring Record HYDRO
Project: 1425 Providence Road South
Project No: 190425.20
Location: Waxhaw, North Carolina
Date: 5/4/19
Method: HSA-ASTM D1586
GWT at Drilling: Not Encountered
G.S. Elev:
Driller: EDPS (Auto Hammer)
GWT at 24 hrs: N/A (Boring Backfilled)
Logged By: TMB
LL
w
t
0
o
E
cn
Description
N
Standard Penetration Test
(Blows/Foot)
0 10 20 30 40 50 60 70 80 90 100
Topsoil (Approximately 6 inches)
Stiff red -brown silty clay (CL) (RESIDUUM)
12
40
Stiff to very stiff red -brown fine to medium
sandy clay (CL)
5
10
Ak
16
Very firm gray and brown silty fine to
medium sand (SM)
10
22
Partially weathered rock sampled as gray
silty fine to coarse sand (SM) with rock
fragments
15
Boring Terminated at 15 feet 50/3"
20
25
Remarks:

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B-4 Test Boring Record HYDRO
Project: 1425 Providence Road South
Project No: 190425.20
Location: Waxhaw, North Carolina
Date: 5/4/19
Method: HSA-ASTM D1586
GWT at Drilling: Not Encountered
G.S. Elev:
Driller: EDPS (Auto Hammer)
GWT at 24 hrs: N/A (Boring Backfilled)
Logged By: TMB
t
o
Standard Penetration Test
LL
E
Description
N
(Blows/Foot)
w
0
cn
0 10 20 30 40 50 60 70 80 90 100
Topsoil (Approximately 6 inches)
Firm to stiff red -brown and tan silty clay (CL)
(RESIDUUM)
6
�
5
10
12
Stiff red -brown fine sandy clay (CL)
10
15
15
Boring Terminated at 15 feet 14
20
25
Remarks:

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B-5 Test Boring Record HYDRO
Project: 1425 Providence Road South
Project No: 190425.20
Location: Waxhaw, North Carolina
Date: 5/4/19
Method: HSA-ASTM D1586
GWT at Drilling: Not Encountered
G.S. Elev:
Driller: EDPS (Auto Hammer)
GWT at 24 hrs: N/A (Boring Backfilled)
Logged By: TMB
t
o
Standard Penetration Test
LL
E
Description
N
(Blows/Foot)
w
0
cn
0 10 20 30 40 50 60 70 80 90 100
Topsoil (Approximately 6 inches)
Stiff to very stiff red -brown silty clay (CL)
(RESIDUUM)
14
5
20
Stiff to very stiff red -brown fine to medium
sandy silt (ML)
17
10
20
15
Boring Terminated at 15 feet 23
20
25
Remarks:

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P-1 Test Boring Record HYDRO
Project: 1425 Providence Road South
Project No: 190425.20
Location: Waxhaw, North Carolina
Date: 5/4/19
Method: HSA-ASTM D1586
GWT at Drilling: Not Encountered
G.S. Elev:
Driller: EDPS (Auto Hammer)
GWT at 24 hrs: N/A (Boring Backfilled)
Logged By: TMB
t
o
Standard Penetration Test
LL
E
Description
N
(Blows/Foot)
w
0
cn
0 10 20 30 40 50 60 70 80 90 100
'°'
Topsoil (Approximately 6 inches)
Dense tan silty fine to coarse sand (SM) with
rock fragments (RESIDUUM)
41
Very firm tan clayey fine to medium sand
,.
(SC)
5
21
Boring Terminated at 5 feet
10
15
20
25
Remarks:

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P-2 Test Boring Record HYDRO
Project: 1425 Providence Road South
Project No: 190425.20
Location: Waxhaw, North Carolina
Date: 5/4/19
Method: HSA-ASTM D1586
GWT at Drilling: Not Encountered
G.S. Elev:
Driller: EDPS (Auto Hammer)
GWT at 24 hrs: 9 feet
Logged By: TMB
LL
w
t
0
o
E
cn
Description
N
Standard Penetration Test
(Blows/Foot)
0 10 20 30 40 50 60 70 80 90 100
Topsoil (Approximately 6 inches)
Loose tan clayey fine to medium sand (SC)
(RESIDUUM)
9
Firm to very firm tan to red -brown silty fine to
coarse sand (SM)
5
13
30
1
10
29
15
22
Very stiff tan fine sandy silt (ML)
20
Boring Terminated at 20 feet 18
25
Remarks:

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P-3 Test Boring Record HYDRO
Project: 1425 Providence Road South
Project No: 190425.20
Location: Waxhaw, North Carolina
Date: 5/4/19
Method: HSA-ASTM D1586
GWT at Drilling: Not Encountered
G.S. Elev:
Driller: EDPS (Auto Hammer)
GWT at 24 hrs: N/A (Boring Backfilled)
Logged By: TMB
t
o
Standard Penetration Test
LL
E
Description
N
(Blows/Foot)
w
0
cn
0 10 20 30 40 50 60 70 80 90 100
"
Topsoil (Approximately 4 inches)
Stiff to very stiff red -brown and tan silty clay
(CL) (RESIDUUM)
13
5
AL
Boring Terminated at 5 feet 17
10
15
20
25
Remarks:

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R-1 Test Boring Record HYDRO
Project: 1425 Providence Road South
Project No: 190425.20
Location: Waxhaw, North Carolina
Date: 5/4/19
Method: HSA-ASTM D1586
GWT at Drilling: Not Encountered
G.S. Elev:
Driller: EDPS (Auto Hammer)
GWT at 24 hrs: N/A (Boring Backfilled)
Logged By: TMB
t
o
Standard Penetration Test
LL
E
Description
N
(Blows/Foot)
w
0
cn
0 10 20 30 40 50 60 70 80 90 100
Topsoil (Approximately 6 inches)
Very stiff tan silty clay (CL) (RESIDUUM)
22
Very firm to dense silty fine to coarse sand
(SM)
5
26
34
10
30
15
26
Boring Terminated at 15 feet
20
25
Remarks:

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R-2 Test Boring Record HYDRO
Project: 1425 Providence Road South
Project No: 190425.20
Location: Waxhaw, North Carolina
Date: 5/4/19
Method: HSA-ASTM D1586
GWT at Drilling: Not Encountered
G.S. Elev:
Driller: EDPS (Auto Hammer)
GWT at 24 hrs: N/A (Boring Backfilled)
Logged By: TMB
t
o
Standard Penetration Test
LL
E
Description
N
(Blows/Foot)
w
0
cn
0 10 20 30 40 50 60 70 80 90 100
Topsoil (Approximately 6 inches)
Stiff tan fine sandy silt (ML) (RESIDUUM)
10
40
5
11
Firm to very firm tan to red -brown silty fine to
medium sand (SM)
20
10
22
15
Boring Terminated at 15 feet 25
20
25
Remarks: