SW6240205_Stormwater Report_20240223

ECS SOUTHEAST, LLP "Setting the Standard for Service"
Geotechnical • Construction Materials • Environmental • Facilities NC Registered Engineering Firm F-1078
NC Registered Geologists Firm C-406
SC Registered Engineering Firm 3239
May 18, 2023
Mr. Michael Holborn
SfL+a Architects
214 Burgess Street
Fayetteville, North Carolina 28301
Reference: Report of Seasonal High Water Table Estimation and Infiltration Testing
Hoke County High School
Raeford, Hoke County, North Carolina
ECS Project No. 49.20343
Dear Mr. Holborn:
ECS Southeast, LLP (ECS) recently conducted a seasonal high water table (SHWT) estimation
and infiltration testing within the stormwater control measure (SCM) area(s) at 505 South Bethel
Road in Raeford, Hoke County, North Carolina. This letter, with attachments, is the report of
our testing.
Field Testing
On May 15, 2023, ECS conducted an exploration of the subsurface soil conditions, in
accordance with the NCDEQ Stormwater Design Manual section A-2, at four requested
locations shown on the attached Boring Location Plan (Figure 1). ECS used GPS equipment in
order to determine the boring locations. The purpose of this exploration was to obtain
subsurface information of the in situ soils for the SCM area(s). ECS explored the subsurface
soil conditions by advancing one hand auger boring into the existing ground surface at each of
the requested boring locations. ECS visually classified the subsurface soils and obtained
representative samples of each soil type encountered. ECS also recorded the SHWT elevation
observed at the time of the hand auger borings. The attached Infiltration Testing Form provides
a summary of the subsurface conditions encountered at the hand auger boring locations.
The SHWT elevation was estimated at the boring locations below the existing grade elevation.
A summary of the findings are as follows:
Location SHWT
I-1 91 inches
1-2 94 inches
1-3 90 inches
1-4 87 inches
ECS has conducted four infiltration tests utilizing a compact constant head permeameter near
the hand auger borings in order to estimate the infiltration rate for the subsurface soils.
Infiltration tests are typically conducted at two feet above the SHWT or in the most restrictive
soil horizon. Tests in clayey conditions are conducted for durations of up to 30 minutes. If a
more precise hydraulic conductivity value is desired for these locations, then ECS recommends
collecting samples and performing laboratory permeability testing.
ECS Capitol Services,PLLC • ECS Florida,LLC • ECS Mid-Atlantic,LLC • ECS Midwest,LLC • ECS Southeast,LLP • ECS Texas, LLP
www.ecslimited.com

Report of SHWT Estimation and Infiltration Testing
Hoke County High School
Raeford, Hoke County, North Carolina
ECS Project No. 49.20343
May 18, 2023
Field Test Results
Below is a summary of the infiltration test results:
Location Description Depth Inches/
hour
I-1 Tan/orange/gray clayey SAND 67 inches 0.16
1-2 Tan/orange/gray clayey SAND 70 inches 0.10
1-3 Brown/tan/orange clayey SAND 66 inches 0.09
1-4 Tan/orange/gray clayey SAND 63 inches 0.06
Infiltration rates and SHWT may vary within the proposed site due to changes in elevation, soil
classification and subsurface conditions. ECS recommends that a licensed surveyor provide
the elevations of the boring locations.
Closure
ECS's analysis of the site has been based on our understanding of the site, the project
information provided to us, and the data obtained during our exploration. If the project
information provided to us is changed, please contact us so that our recommendations can be
reviewed and appropriate revisions provided, if necessary. The discovery of any site or
subsurface conditions during construction which deviate from the data outlined in this
exploration should be reported to us for our review, analysis and revision of our
recommendations, if necessary. The assessment of site environmental conditions for the
presence of pollutants in the soil and groundwater of the site is beyond the scope of this
geotechnical exploration.
ECS appreciates the opportunity to provide our services to you on this project. If you have any
questions concerning this report or this project, please contact us.
Respectfully,
ECS SOUTHEAST, LLP
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K. Brooks Wall W. Brandon Fulton, PSC, PWS, LSS
Project Manager Environmental Department Manager
[e-mail] [e-mail]
910-686-9114 704-525-5152
Attachments: Figure 1 - Boring Location Plan
Infiltration Testing Form
GBA Document
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Provided by: Google Earth
ECS Project#49.20343
May 16, 2023
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Infiltration Testing Form
Hoke County High School
Raeford, Hoke County, North Carolina
ECS Project No. 49.20343
May 16, 2023
Location Depth USCS Soil Description
-1 0-8" SP Tan fine SAND
8"-91" SC Tan/orange/gray clayey SAND
Seasonal High Water Table was estimated to be at 91 inches below the
existing grade elevation.
Test was conducted at 67 inches below existing grade elevation
Infiltration Rate: 0.16 inches per hour
Location Depth USCS Soil Description
1-2 0-12" SP Tan/brown fine SAND
12"-97" SC Tan/orange/gray clayey SAND
Seasonal High Water Table was estimated to be at 94 inches below the
existing grade elevation.
Test was conducted at 70 inches below existing grade elevation
Infiltration Rate: 0.10 inches per hour
Location Depth USCS Soil Description
1-3 0-10" SP Tan fine SAND
10"-94" SC Brown/tan/orange clayey SAND
Seasonal High Water Table was estimated to be at 90 inches below the
existing grade elevation.
Test was conducted at 66 inches below existing grade elevation
Infiltration Rate: 0.09 inches per hour
Location Depth USCS Soil Description
1-4 0-8" SP Tan fine SAND
8"-90" SC Tan/orange/gray clayey SAND
Seasonal High Water Table was estimated to be at 87 inches below the
existing grade elevation.
Test was conducted at 63 inches below existing grade elevation
Infiltration Rate: 0.06 inches per hour

Important Information about This
(-- Geotecbnical-[ngineering
Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.
While you cannot eliminate all such risks, you can manage them. The following information is provided to help.
The Geoprofessional Business Association (GBA) Typical changes that could erode the reliability of this report include
has prepared this advisory to help you—assumedly those that affect:
a client representative—interpret and apply this • the site's size or shape;
geotechnical-engineering report as effectively • the function of the proposed structure,as when it's
as possible. In that way, clients can benefit from changed from a parking garage to an office building,or
a lowered exposure to the subsurface problems from a light-industrial plant to a refrigerated warehouse;
• the elevation,configuration,location,orientation,or
that,for decades, have been a principal cause of weight of the proposed structure;
construction delays, cost overruns, claims, and • the composition of the design team;or
disputes. If you have questions or want more • project ownership.
information about any of the issues discussed below,
contact your GBA-member geotechnical engineer. As a general rule,always inform your geotechnical engineer of project
Active involvement in the Geoprofessional Business changes-even minor ones-and request an assessment of their
Association exposes geotechnical engineers to a impact.The geotechnical engineer who prepared this report cannot accept
wide array of risk-confrontation techniques that can responsibility or liability for problems that arise because the geotechnical
be of genuine benefit for everyone involved with a engineer was not informed about developments the engineer otherwise
construction project. would have considered.
This Report May Not Be Reliable
Geotechnical-Engineering Services Are Performed for Do not rely on this report if your geotechnical engineer prepared it:
Specific Purposes, Persons, and Projects • for a different client;
Geotechnical engineers structure their services to meet the specific • for a different project;
needs of their clients.A geotechnical-engineering study conducted for a different site(that may or may not include all or a
for a given civil engineer will not likely meet the needs of a civil- portion of the original site);or
works constructor or even a different civil engineer.Because each • before important events occurred at the site or adjacent
geotechnical-engineering study is unique,each geotechnical- to it;e.g.,man-made events like construction or
engineering report is unique,prepared solely for the client.Those who environmental remediation,or natural events like floods,
rely on a geotechnical-engineering report prepared for a different client droughts,earthquakes,or groundwater fluctuations.
can be seriously misled.No one except authorized client representatives
should rely on this geotechnical-engineering report without first Note,too,that it could be unwise to rely on a geotechnical-engineering
conferring with the geotechnical engineer who prepared it.And no one report whose reliability may have been affected by the passage of time,
-not even you-should apply this report for any purpose or project except because of factors like changed subsurface conditions;new or modified
the one originally contemplated. codes,standards,or regulations;or new techniques or tools.If your
geotechnical engineer has not indicated an`apply-by"date on the report,
Read this Report in Full ask what it should be,and,in general,if you are the least bit uncertain
Costly problems have occurred because those relying on a geotechnical- about the continued reliability of this report,contact your geotechnical
engineering report did not read it in its entirety.Do not rely on an engineer before applying it.A minor amount of additional testing or
executive summary.Do not read selected elements only.Read this report analysis-if any is required at all-could prevent major problems.
in full.
Most of the "Findings" Related in This Report Are
You Need to Inform Your Geotechnical Engineer Professional Opinions
about Change Before construction begins,geotechnical engineers explore a site's
Your geotechnical engineer considered unique,project-specific factors subsurface through various sampling and testing procedures.
when designing the study behind this report and developing the Geotechnical engineers can observe actual subsurface conditions only at
confirmation-dependent recommendations the report conveys.A few those specific locations where sampling and testing were performed.The
typical factors include: data derived from that sampling and testing were reviewed by your
• the client's goals,objectives,budget,schedule,and geotechnical engineer,who then applied professional judgment to
risk-management preferences; form opinions about subsurface conditions throughout the site.Actual
• the general nature of the structure involved,its size, sitewide-subsurface conditions may differ-maybe significantly-from
configuration,and performance criteria; those indicated in this report.Confront that risk by retaining your
• the structure's location and orientation on the site;and geotechnical engineer to serve on the design team from project start to
• other planned or existing site improvements,such as project finish,so the individual can provide informed guidance quickly,
retaining walls,access roads,parking lots,and whenever needed.
underground utilities.

This Report's Recommendations Are perform their own studies if they want to,and be sure to allow enough
Confirmation-Dependent time to permit them to do so.Only then might you be in a position
The recommendations included in this report-including any options to give constructors the information available to you,while requiring
or alternatives-are confirmation-dependent.In other words,they are them to at least share some of the financial responsibilities stemming
not final,because the geotechnical engineer who developed them relied from unanticipated conditions.Conducting prebid and preconstruction
heavily on judgment and opinion to do so.Your geotechnical engineer conferences can also be valuable in this respect.
can finalize the recommendations only after observing actual subsurface
conditions revealed during construction.If through observation your Read Responsibility Provisions Closely
geotechnical engineer confirms that the conditions assumed to exist Some client representatives,design professionals,and constructors do
actually do exist,the recommendations can be relied upon,assuming not realize that geotechnical engineering is far less exact than other
no other changes have occurred.The geotechnical engineer who prepared engineering disciplines.That lack of understanding has nurtured
this report cannot assume responsibility or liability for confirmation- unrealistic expectations that have resulted in disappointments,delays,
dependent recommendations if you fail to retain that engineer to perform cost overruns,claims,and disputes.To confront that risk,geotechnical
construction observation. engineers commonly include explanatory provisions in their reports.
Sometimes labeled"limitations;'many of these provisions indicate
This Report Could Be Misinterpreted where geotechnical engineers'responsibilities begin and end,to help
Other design professionals'misinterpretation of geotechnical- others recognize their own responsibilities and risks.Read these
engineering reports has resulted in costly problems.Confront that risk provisions closely.Ask questions.Your geotechnical engineer should
by having your geotechnical engineer serve as a full-time member of the respond fully and frankly.
design team,to:
• confer with other design-team members, Geoenvironmental Concerns Are Not Covered
• help develop specifications, The personnel,equipment,and techniques used to perform an
• review pertinent elements of other design professionals' environmental study-e.g.,a"phase-one"or"phase-two"environmental
plans and specifications,and site assessment-differ significantly from those used to perform
• be on hand quickly whenever geotechnical-engineering a geotechnical-engineering study.For that reason,a geotechnical-
guidance is needed. engineering report does not usually relate any environmental findings,
conclusions,or recommendations;e.g.,about the likelihood of
You should also confront the risk of constructors misinterpreting this encountering underground storage tanks or regulated contaminants.
report.Do so by retaining your geotechnical engineer to participate in Unanticipated subsurface environmental problems have led to project
prebid and preconstruction conferences and to perform construction failures.If you have not yet obtained your own environmental
observation. information,ask your geotechnical consultant for risk-management
guidance.As a general rule,do not rely on an environmental report
Give Constructors a Complete Report and Guidance prepared for a different client,site,or project,or that is more than six
Some owners and design professionals mistakenly believe they can shift months old.
unanticipated-subsurface-conditions liability to constructors by limiting
the information they provide for bid preparation.To help prevent Obtain Professional Assistance to Deal with Moisture
the costly,contentious problems this practice has caused,include the Infiltration and Mold
complete geotechnical-engineering report,along with any attachments While your geotechnical engineer may have addressed groundwater,
or appendices,with your contract documents,but be certain to note water infiltration,or similar issues in this report,none of the engineer's
conspicuously that you've included the material for informational services were designed,conducted,or intended to prevent uncontrolled
purposes only.To avoid misunderstanding,you may also want to note migration of moisture-including water vapor-from the soil through
that"informational purposes"means constructors have no right to rely building slabs and walls and into the building interior,where it can
on the interpretations,opinions,conclusions,or recommendations in cause mold growth and material-performance deficiencies.Accordingly,
the report,but they may rely on the factual data relative to the specific proper implementation of the geotechnical engineer's recommendations
times,locations,and depths/elevations referenced. Be certain that will not of itself be sufficient to prevent moisture infiltration.Confront
constructors know they may learn about specific project requirements, the risk of moisture infiltration by including building-envelope or mold
including options selected from the report,only from the design specialists on the design team.Geotechnical engineers are not building-
drawings and specifications.Remind constructors that they may envelope or mold specialists.
5 GEOPROFESSIONAL
BUSINESS
t ASSOCIATION
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e-mail:[e-mail] wwwgeoprofessional.org
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