NC0024333_15 MGD EQ Basin Construction_20210518

Strickland, Bev
From: Russell Colbath <[e-mail]>
Sent: Tuesday, May 18, 2021 10:30 AM
To: Basinger, Corey
Cc: Scheller, Roberto; Kyle Ketchum; 'Struve, James N.'
Subject: [External] City of Monroe NOV - 2021-LV-0287
Attachments: Engineer Report WWTP Flow Equalization Improvements 7-17-20.pdf
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Good afternoon Corey,
I wanted to touch base on the above NOV dated April 27, 2021.
Proactively addressing I&I in our collections system and the negative impact it has at our WWTP has been a priority for
many years.
We recently assembled a PER (attached) and sent it to Christyn Fertenbaugh on 7-21-20. It outlined plans to construct
additional 15 MG EQ storage at our WWTP to improve storm/wet weather resiliency. We are preparing to submit
permit applications/construction drawings, and then bid this $4 million project with anticipated completion in spring
2022. Anything you can do to help expedite permitting for dam safety, erosion control , and A to C would be
appreciated.
In the PER we also outlined our aggressive I&I control program made up of the following:
• Sewer main replacement by City Water Resources crews using pipe bursting technology.
• Sewer main replacement using cured in place (CIPP) lining. The current project approach is to bid
annual "find and fix" contracts where CCTV is utilized to find high priority repairs which are then
rehabilitated using CIPP.
• Manhole rehabilitation using spray on cemetatious liners (calcium aluminate for high corrosion areas).
• Smoke testing of sewer collection system basins, with current goal of 20% of the system per year. Top
of ground repairs, such as sewer cleanouts, etc., are completed when found.
• Sewer main and lateral point repairs, either by City crews or by CIPP contractors.
• Regular sewer outfall inspections after all 2-inch or greater rainfall events.
All in all we are spending close to $1.0 million annually on collection system renewal and replacements. This on top of
the noted investment in added EQ storage.
Based on all factors, we are not planning to pursue an SOC at this time (as noted in your letter and NOV).
I wanted to share this information to ensure you that we are working very hard to keep our collection system and
WWTP in full compliance with their respective permits.
Thank you.
R wlyse).2. C d th-ci th', P.E.
i

City of Monroe
Water Resources Director
704-282-4624
rcolbath@monroenc. orq
P nro
North Carolina
E-mail correspondence to and from this address may be subject to North Carolina's public
records laws and if so, may be disclosed.
2

\r1'l0nroe North Carolina
City of Monroe Water Resources
WWTP Flow Equalization Basin Expansion
Preliminary Engineering Report
July 20, 2020
R�(i. Co-lbat-h; PE
[e-mail]
704-282-4624
Project Background
The City of Monroe Water Resources Department operates a wastewater treatment plant (WWTP)
located at 775 Treeway Drive in Monroe, North Carolina. The plant meets the wastewater treatment
needs of the City of Monroe and the Union County East Side Sewer System. The WWTP has a current
capacity of 10.4 MGD, with 2.65 MGD allocated to Union County via interlocal agreement. The WWTP
also has a 10 MG earthen flow equalization (EQ) basin to divert high influent flows during wet weather
events.
The WWTP Master Plan, completed in 2008 by Hazen and Sawyer, identified the future need for an
additional 10 MG of flow EQ storage (Attachment 1), generally to be timed with the next WWTP
expansion. The Plan does indicate that this added EQ storage could be beneficial prior to the WWTP
expansion based on need and available funding. The WWTP expansion, potentially to 15.0 MGD in
partnership with Union County, is projected to occur in the early 2030’s.
During high intensity and extended duration rainfall events, the WWTP has experienced flows
exceeding the hydraulic capacity and EQ storage volume of the plant. This has resulted in the bypass
of some treatment processes. All bypass events have been reported to the North Carolina Department
of Environmental Quality (NCDEQ) per state standards and pursuant to the City’s NPDES permit. Based
on all considerations, the City believes it is prudent to move forward with the design, permitting, and
construction of expanded EQ storage basin volume to improve WWTP operations, permit compliance,
and prepare for the future WWTP expansion.
Sewer Collection System Asset Management
WWTP hydraulic overloading during heavy wet weather events is an indication of sanitary sewer
collection system inflow and infiltration (I&I) and system rehabilitation needs. The City has a
comprehensive sewer asset management program and is committed to collection system upgrades and
repairs. The City sewer system asset management plan includes the following:
Sewer main replacement by City Water Resources crews using pipe bursting technology.
Sewer main replacement using cured in place (CIPP) lining. The current project approach is to
bid annual “find and fix” contracts where CCTV is utilized to find high priority repairs which are
then rehabilitated using CIPP.
Manhole rehabilitation using spray on cemetatious liners (calcium aluminate for high corrosion
areas).
Smoke testing of sewer collection system basins, with current goal of 20% of the system per
year. Top of ground repairs, such as sewer cleanouts, etc., are completed when found.
Sewer main and lateral point repairs, either by City crews or by CIPP contractors.
Regular sewer outfall inspections after all 2-inch or greater rainfall events.
In 2014, the City established a goal to replace or rehabilitate 1% of the collections system sewer main
footage annually. Attachment 2 shows the historical performan ce toward meeting this goal.
Attachment 3 shows the financial commitment to sewer asset management, totaling $6.1 million since
FY2010. The City will continue to aggressively identify, assess, and rehabilitate/replace aging sewer
collection system infrastructure to limit rainfall I&I into the system.
WWTP Wet Weather Flow Analysis
The City’s sewer collection system response to rainfall events, and the associated high flow impact to
the WWTP, varies greatly with the type, intensity, spacial distribution, and duration of the rainfall
event. It is also significantly influenced by antecede nt moisture conditions, and ground water levels.
Table 1 shows the historical storm events for the past 5 years that resulted in hydraulic overloading
and subsequent WWTP process bypass.
Table 1.
Date(s) Rainfall (In.) Reported WWTP Bypass (Gal.)
March 7-8, 2014 2.0” 2,221,965
April 19-20, 2014 2.75” 3,562,960
October 3-7, 2015 8.75” 1,022,021
November 2-3, 2015 4.5” 2,441,280
2016 None
2017 None
September 15-17, 2018 10.9” 10,803,690 (Hurricane Florence = Design Storm)
2019 None
February 7, 2020 3.4” 4,223,750
May 20-21, 2020 7.0” 12,146,000 (note 1)
May 28, 2020 2.5” 531,000 (note 1)
Note 1. Post storm collection system inspection found 2 manholes with covers off. Bypass volume likely not
representative of historical performance.
Based on all data and considerations, the September 2018 storm event (Hurricane Florence) was
selected as the design storm event for additional EQ storage analysis. The following data is relevant to
the analysis:
Recurrence frequency – based on NOAA Atlas 14, approximately 200-year event.
WWTP maximum hydraulic capacity (flow throughput) = 22 MGD.
Peak WWTP influent flow rate during Hurricane Florence = 46 MGD.
Total WWTP process bypass volume reported to NCDEQ = 10.8 MG.
The 200-year recurrence frequency of this storm is greater than required design standards. However,
using this storm for EQ storage volume planning provides a safety factor for climate change uncertainty
where future storms may be more frequent and intense, future flow growth from economic
development, plus added storage to protect the WWTP until the planned future expansion.
Table 2 shows the analysis of WWTP flow and EQ volume needed to eliminate WWTP flow bypass
during the design storm. The current 10.4 MGD WWTP is capable of sustained hydraulic throughput of
approximately 22 MGD for the extended periods of time typical of most large rain events. The table
Table 2. WWTP Influent Flow Data Rain
US Climate
Data.com
Hurricane Florence 9/15/2018 0.81
9/16/2018 5.81
9/17/2018 4.3
10.92 Inches
Date Time
Total City
Influent
Total County
Influent
Total WWTP
Influent
WWTP
Hydraulic
Rate Flow to EQ
Volume to
EQ
1:00 MGD MGD MGD MGD MGD MG
9/16/2018 3:25 AM 15.0 7.0 22.0 22 0.0 0.00
4:25 AM 18.9 8.1 27.0 22 5.0 0.21
5:25 AM 22.3 8.3 30.6 22 8.6 0.36
6:25 AM 25.2 8.3 33.5 22 11.5 0.48
7:25 AM 30.1 8.9 39.0 22 17.0 0.71
8:25 AM 31.0 7.3 38.3 22 16.3 0.68
9:25 AM 31.7 9.1 40.8 22 18.8 0.78
10:25 AM 32.4 10.0 42.4 22 20.4 0.85
11:25 AM 33.1 10.0 43.1 22 21.1 0.88
12:25 PM 34.1 10.0 44.1 22 22.1 0.92
1:25 PM 35.5 10.0 45.5 22 23.5 0.98
2:25 PM 35.8 10.0 45.8 22 23.8 0.99
3:25 PM 36.1 10.0 46.1 22 24.1 1.00
4:25 PM 36.1 10.0 46.1 22 24.1 1.00
5:25 PM 36.3 10.0 46.3 22 24.3 1.01
6:25 PM 35.9 10.0 45.9 22 23.9 1.00
7:25 PM 36.0 9.8 45.8 22 23.8 0.99
8:25 PM 35.9 9.7 45.6 22 23.6 0.98
9:25 PM 35.7 9.6 45.3 22 23.3 0.97
10:25 PM 35.1 9.4 44.5 22 22.5 0.94
11:25 PM 34.9 8.4 43.3 22 21.3 0.89
9/17/2018 12:25 AM 34.2 9.3 43.5 22 21.5 0.90
1:25 AM 33.7 7.7 41.4 22 19.4 0.81
2:25 AM 33.6 8.2 41.8 22 19.8 0.83
3:25 AM 32.9 7.3 40.2 22 18.2 0.76
4:25 AM 32.1 6.9 39.0 22 17.0 0.71
5:25 AM 31.8 6.6 38.4 22 16.4 0.68
6:25 AM 19.8 5.2 25.0 22 3.0 0.13
6:38 AM 17.4 4.6 22 22 0.0 0.00
7:38 AM Time WWTP reached 22 MGD Total EQ Volume (MG)21.42
EQ Reserve for Filter Backwash (MG)1.5
Total Needed EQ Volume (MG) 22.92
shows only those hours where the total WWTP influent flow exceeded 22 MGD. Based on the design
storm, including an EQ reserve for filter backwash, 23 MG of total EQ storage is needed. Therefore, 13
MG of added EQ storage is needed to supplement the existing 10 MG EQ basin.
Proposed EQ Basin Expansion
Figure 1 shows the preliminary concept for a proposed EQ basin expansion. The land parcel was
purchased by the City in 2009 and contains 23.75 acres. It is zoned General Industrial which will
support the intended project land use. The parcel is wooded with topography generally sloping to the
north toward Richardson Creek. While a minimum of 13 MGD is indicated by the design storm, the city
believes it is prudent to maximize the EQ volume on the property. The incremental cost of adding 2
MGD, to create a 15 MG basin, will likely be low. The EQ basin project will be funded by the City’s
Water and Sewer Enterprise fund and with f unding from Union County consistent with the interlocal
agreement. No state or federal funding will be used. The following factors and considerations will
form the basis of detailed design, permitting, and construction.
Geotechnical Evaluation – Attachment 4 provides the results of the preliminary geotechnical
evaluation conducted by GTA and Associates. Additional geotechnical testing will be completed during
design and construction as needed. Generally, the evaluation shows the site is suita ble for the
intended purpose.
NCDEQ Dam Safety – Preliminary communications with NCDEQ Dam Safety staff have occurred
concerning the new EQ basin. The City will submit a Jurisdictional Determination/Hazard Classification
Request as part of the design phase of the project. It is the City’s intent to limit the EQ basin
embankment height to less than 25-feet and less than 50 ac-ft (16MG+/-) of storage to meet the
exemption requirements of high hazard dam classification. The City’s existing EQ basin constructed in
2004 did not require such permitting due to the earthen berm dimensions and EQ basin volume.
Wetlands and Endangered Species – A preliminary investigation of the site for wetlands and
endangered species was conducted by a Hazen and Sawyer environmental scientist on June 19, 2020.
Attachment 5 shows the preliminary findings. There were no areas of concern identified. Any
additional evaluations of these items will be conducted during project design, and in coordination with
NCDEQ.
Earthen EQ Basin Design Concept – The proposed earthen EQ basin will use similar design concepts as
the existing 10 MG EQ basin. The basin will be lined with a geosynthetic clay liner (GCL) to achieve the
required low permeability and hydraulic barrier. Operational cover (typically 18 inches) will protect the
GCL from erosion or damage. Preliminary analysis indicates that the effective operating range could be
from 504 to 511 feet elevation +/-, with typical berm cross slopes of approximately 1:3. The force main
discharge inlet will be designed to protect the basin floor and liner using large rip-rap, concrete, or
other energy dissipating features to be determined during design. An NCDEQ Erosion and
Sedimentation Control permit will be obtained for the entire project. The entire basin will be fenced
per NCDEQ requirements.
Proposed 15 MG
EQ Basin
Operating Elevation
504' to 511' +/-
tFIGURE 1
Proposed EQ Basin Expansion (Cont.)
Inlet Force Main Hydraulic Analysis – The inlet force main for the new EQ basin will be a combination
of 24 and 30 inch piping, flow control valve (motorized eccentric plug valve), flow meter, and
appropriately placed isolation valves. The force main will be connected to the existing 24-inch
discharge header for WWTP influent pump stations (IPS) #1 and #2 that have the following
characteristics:
IPS #1
Four (4) identical pumps (Fairbanks Morse 8” 54x6 pump curve (Attachment 6).
Individual capacity 3440 GPM at 80-feet TDH.
All pumps replaced/new in 2018.
IPS #2
Two (2) identical pumps (Fairbanks Morse 10” M5440 pump curve (Attachment 7).
Individual capacity 5800 GPM at 80-feet TDH.
All pumps replaced/new in 2018.
Note: Union County system flows are pumped to the WWTP screenings building by separate pump stations.
During heavy rainfall events, after the WWTP total influent flow reaches 22 MGD, operations staff
activate flow diversion to EQ basin storage to maintain steady flow rates through the plant. With a
new/second EQ basin available, it is anticipated that in the early stages of a rainfall event the existing
EQ basin will be activated first as has been done in the past. As a storm event evolves, and flows
increase, flow diversion will be shifted to the new EQ basin. The anticipated design flow range for the
new EQ basin will be 3 to 20 MGD. A system head curve was developed for the proposed EQ basin
force main using this flow range and the following:
Pipe lengths: 24 Inch = 85LF, 30 Inch = 675LF.
Elevations: Existing Influent pumps 453’, wet well operating level 458’, new EQ basin max 511’.
Hazen Williams Roughness Coefficient for DIP = 120.
Total of minor head losses at maximum flow = 20’.
The system curve indicates that the proposed EQ basin force main will require 77 -feet of total
dynamic head (TDH) to deliver the desired 20 MGD flow rate to the basin, at the maximum basin
level of 511-feet. Review of the attached pump curves and operational data indicate the existing
influent pump stations can meet this flow and TDH while delivering the balance of the influent flow
to the WWTP headworks and screening building. It is important to note that the existing WWTP EQ
basin has an operating range of 509-516’ elevation, compared to the proposed elevation of 504-
511’ for the new EQ basin. This, in addition to the demonstrated flow diversion capacity of the
existing EQ basin and force mains, provides added confirmation that the proposed force main
system will deliver the desired 20 MGD flow rate to the new basin.
The existing filter backwash waste pit pumps that currently discharge to the existing 10 MG EQ basin
will be connected to the new force main with appropriate valving to allow discharge to either EQ basin
(See Figure 1.). This will allow operational flexibility, promote odor control, and limit anaerobic
conditions in the stored wastewater. Given that the new EQ basin operating range will be 5 feet +/-
lower than the existing EQ basin, the performance characteristics of the existing backwash waste pit
pumps will function properly with the new EQ basin.
Outlet Piping/ Return Flow to WWTP
After each rainfall event, historical records show that the WWTP influent flow drops quickly as the
sewer collection system I&I dissipates. As the total WWTP flow drops under 22 MGD, operations staff
initiate returning stored wastewater back into the plant at the appropriate timing and flow rate so as
not to overload WWTP processes. The exisiting EQ basin pumps return flow to the WWTP process at a
maximum flow rate of 4.0 MGD. This allows dewatering of the 10 MG basin in 48 to 72 hours.
The new EQ basin will be dewatered using a flow control valve, outlet meter, and 20-inch pipe. The
return flow to the WWTP will utilize the exising 30-inch sewer collection system interceptor as shown
on Figure 1. As-built drawings for the 30-inch pipe show a slope of 0.0014 from manhole 6 to the
termination at the WWTP influent pump stations. Using Mannings equation with n=0.013 and as-built
slope data, the full pipe capacity is 9.97 MGD. Field measurments of this 30-inch interceptor after
rainfall events subside indicate a normal flow depth of 5-inches. This is because the exisitng 54-inch
40
45
50
55
60
65
70
75
80
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0Total Dynamic Head (FT)Flow Rate (MGD)
Proposed WWTP EQ Basin
System Head-Discharge Curve EQ Forcemain
sewer interceptor on the opposite (north) side of Richardson Creek carries the majority of flow to the
WWTP. The 30-inch interceptor acts as a high flow relief main. This allows the 30-inch pipe to quickly
return to normal base flow levels after a rain event. The proposed return flow rates from the new EQ
basin will range from 1 to 5 MGD. Therefore the 30-inch interceptor has sufficient capacity to receive
this flow without surcharging.
EQ Basin Operations, Instrumentation
The new EQ basin will be operated by WWTP staff as described above and in coordination with the
existing EQ basin. The following instrumentation will be available to operators via SCADA telemetry:
Force main influent flow rate
EQ basin level
EQ basin effluent flow rate
SCADA and localized alarm annunciators will be installed to alert operators of high or low operational
values for flow, level, etc.
Control of Odors, Anaerobic Conditions, and limiting WWTP Adverse Impacts
The WWTP staff have successfully operated the existing EQ basin for many years. The key to avoiding
odors and anaerobic condition is to dewater the basin immediately after high flow events when the
WWTP influent flow rate (wet weather flows) drops below 22 MGD. The discharge of filter backwash
water to the EQ basins also plays an important role, bringing in tertiary effluent that contains dissolved
oxygen and a chlorine residual of 1.0 mg/l +/-. Operations data shows that the WWTP will be able to
return flow from both EQ basins after major rain events, with capacity to dewater the basins on an
average of 96 hours +/-. This combined with the backwash water additions will help avoid odors,
septic conditions, and any adverse impacts to the WWTP process.
For the existing EQ basin, removal of any accumulated solids is managed by contracting a floating
dredge to pump solids to a dewatering belt press, with the dewatered solids sent to the Anson County
Landfill after appropriate sampling. This has only been needed on an interval of approximately 5 years.
Solids accumulations in the new EQ basin will be managed and removed using the same approach.
Summary
The City of Monroe Water Resources Department is committed to operating and maintain their
wastewater collection and treatment system in an effective, efficient, and environmentally responsible
way. This report provides the framework and direction to move forward with the design, permitting,
and construction of expanded WWTP EQ storage capacity. This expansion will improve WWTP
operations, permit compliance, and prepare the city for the future WWTP expansion planned for the
early 2030’s.
List of Attachments
1.Hazen and Sawyer Engineering – WWTP 2008 Master Plan Layout with New EQ Storage
2.Sewer Infrastructure Renewal/Replacement Data
3.Sewer Asset Management Program History
4.Preliminary Geo Technical Report
5.Preliminary Investigation for Wetlands and Endangered Species
6.Existing WWTP Influent Pump Station #1 Pump Curve (Typ. Of 4)
7.Existing WWTP Influent Pump Station #2 Pump Curve (Typ. Of 2)
Attachment 1
Attachment 2
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0.20%
0.40%
0.60%
0.80%
1.00%
1.20%
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4,000
6,000
8,000
10,000
12,000
14,000
16,000
11 12 13 14 15 16 17 18 19 20
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%
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FISCAL YEAR
SEWER INFRASTRUCTURE RENEWAL
SLIP LINING LF PIPE BURSTING LF OPEN CUT LF RENEWAL %TARGET %
Attachment 3City of Monroe Water ResourcesSanitary Sewer SystemRehabilitation and Inflow-Infiltration ControlFY 2010FY 2011FY 2012FY 2013FY 2014FY 2015FY 2016FY 2017FY 2018FY 2019FY 2020TotalSewer Main Pipebursting RehabilitationTotal Feet Complete4,0143,1882,0982,9881,9282,7361,1948,4994,7096,7795,60443,737Total Cost (equivalent)$139,650.00$115,793.20$77,483.39$112,403.53$74,163.25$105,123.40$46,239.15$334,072.09$190,107.56$276,757.52$228,027.20$1,699,820.30Sewer Main Lining RehabilitationTotal Feet Complete3,9417,3155,3683,7907,6694,4358,2046,8696,2026,7847,40067,977Total Cost$142,516.00$248,402.90$184,320.30$190,069.10$272,404.29$286,480.03$146,488.35$294,486.93$295,917.22$427,661.60$468,168.69$2,956,915.41Sewer Manhole RehabilitationTotal Manholes311837304504601630142512Total Cost$19,849.50$69,181.90$25,209.90$27,678.40$47,961.40$0.00$52,273.88$0.00$169,393.82$0.00$164,533.59$576,082.39Sewer Main Smoke TestingTotal Feet Complete32,80100000431,199370,003313,323254,929268,0021,670,257Total Cost (Est.)$5,576.17$0.00$0.00$0.00$0.00$0.00$81,108.09$70,641.27$61,438.96$50,551.49$52,967.25$322,283.23Sewer Point Repairs Total Repairs85542472936262634327333Total Cost (equivalent)$9,019.04$75,892.99$47,349.96$64,694.93$32,694.02$56,073.70$87,651.77$52,222.22$56,828.30$1,215.00$71,747.00$555,388.93Note 2FY Total Cost$316,610.71$509,270.99$334,363.55$394,845.96$427,222.96$447,677.13$413,761.24$751,422.51$773,685.87$756,185.61$985,443.74$6,110,490.25Note - FY20 Projection of Actual
REPORT OF PRELIMINARY GEOTECHNICAL SUBSURFACE EXPLORATION
15 MB EQUIALIZATION BASIN
City of Monroe WWTP
Monroe, Union County, North Carolina
July 10, 2020
Prepared For:
City of Monroe
300 W. Crowell Street
Monroe, North Carolina 28112
Attn: Mr. Russ Colbath
Prepared By:
GTA ASSOCIATES, INC.
Geotechnical and Environmental Consultants
710 Peninsula Lane, Suite B
Charlotte, N.C. 28273
[phone] – Office
[phone] - Facsimile
GTA Job No: 35200850
ATTACHMENT 4
GTA ASSOCIATES, INC.
GEOTECHNICAL AND
ENVIRONMENTAL CONSULTANTS
A Practicing Geoprofessional Business Association Member Firm
710 Peninsula Lane, Suite B, Charlotte, NC 28273 Phone: [phone] Fax: [phone]
 Abingdon, MD  Baltimore, MD  Laurel, MD  Frederick, MD  Waldorf, MD  Sterling, VA  Malvern, OH  Somerset, NJ
 NYC Metro  New Castle, DE  Georgetown, DE  York, PA  Quakertown, PA  Charlotte, NC  Raleigh, NC
Visit us on the web at www.gtaeng.com
July 10, 2020
City of Monroe
300 W. Crowell Street
Monroe, North Carolina 28112
Attn: Mr. Russell Colbath, P.E.
Water Resources Director
Re: Report of Preliminary Geotechnical Subsurface Exploration
Proposed 15MG Equalization Basin
City of Monroe Wastewater Treatment Plant
Industrial Drive - +25 Acres
Monroe, Union County, North Carolina
Dear Mr. Colbath:
In accordance with our agreement executed on May 29, 2020, GTA Associates, Inc. (GTA)
has performed a preliminary geotechnical subsurface exploration for a 15-million-gallon
equalization basin located to the west of the existing Wastewater Treatment Plant in Monroe, North
Carolina. The results of the field testing and our preliminary recommendations regarding design and
construction of the proposed equalization basin are included in this report. Unless other
arrangements are made by the City of Monroe, GTA will discard the soil samples within sixty days
from the date of this report.
GTA appreciates the opportunity to assist you with this project. Should you have questions
or require additional information, please contact at our office at [phone].
Sincerely,
GTA ASSOCIATES, INC.
Andrew Beaty
Staff Professional
John P. Wille, P.E.
Vice President
Z:\Project\2020\City of Monroe\WWTP\Report of Preliminary Geotechnical Subsurface Exploration.doc
Job No.
7-10-20
TABLE OF CONTENTS
PAGE
INTRODUCTION .......................................................................................................................... 1
SITE CONDITIONS ....................................................................................................................... 1
PROPOSED CONSTRUCTION .................................................................................................... 2
SITE GEOLOGY ............................................................................................................................ 2
SUBSURFACE EXPLORATION .................................................................................................. 3
SUBSURFACE CONDITIONS ..................................................................................................... 4
LABORATORY TESTING............................................................................................................ 6
PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS ............................................. 7
Preliminary Foundation Support ................................................................................................. 8
Site Grading for Embankments ................................................................................................... 9
Difficult Excavation .................................................................................................................. 10
Subsurface Utilities ................................................................................................................... 11
Surface and Subsurface Drainage ............................................................................................. 12
ADDITIONAL SERVICES .......................................................................................................... 13
LIMITATIONS ............................................................................................................................. 13
ASFE—Important Information About Your Geotechnical Engineering Report
Appendix A – Figures
Figure No. 1 – Site Location Plan
Figure No. 2 – Exploration Location Plan
Figure No. 3 – Site Topography Plan
Appendix B – Soil Boring Logs
Notes for Exploration Logs (1 Sheet)
Summary of Subsurface Exploration (1 Sheet)
Soil Boring Logs (15 Sheets)
Appendix C – Laboratory Results (1 Sheet)
1 
REPORT OF PRELIMINARY GEOTECHNICAL SUBSURFACE EXPLORATION
15 MG EQUALIZATION BASIN – CITY OF MONROE WWTP
MONROE, UNION COUNTY, NORTH CAROLINA
INTRODUCTION
The City of Monroe (Client) is planning to construct a 15 million-gallon equalization basin
located to the west of the existing City of Monroe Wastewater Treatment Plant. The site
encompasses approximately 25 acres of undeveloped wooded land located north of Industrial
Drive and west of the Waste Water Treatment Plant in Monroe, Union County, North Carolina.
Detailed information regarding the design plans and site grading information has not been provided
to us at this time. Please refer the Site Location Plan included as Figure 1 in Appendix A for the
approximate location of the site.
GTA was retained to perform a preliminary geotechnical subsurface exploration of the
project site to characterize the general near-surface subsurface conditions in the proposed
equalization basin area. The scope of this study included a field exploration as well as an
engineering and laboratory analysis. Included in our field exploration were eighteen (15) Standard
Penetration Test borings to depths ranging from approximately 6.1 to 14 feet below the existing
ground surface. Preliminary conclusions and recommendations regarding general site
development were derived from the engineering analysis of the field and laboratory data.
SITE CONDITIONS
The site is located at the north end of Industrial drive and west of the existing waste water
treatment plant in Monroe, Union County, North Carolina. The site encompasses approximately
25 acres of undeveloped land and is designated as Parcel Identification Number (PIN) 09111008.
At the time of our investigation, the subject site is moderately to heavily wooded. The site is
bordered to the west by the waste water treatment plant and Joes Branch Creek, to the north by
Richardson Creek, and to the south by a manufacturing facility and associated parking.
Report of Preliminary Exploration – 15 MG Equalization Basin City of Monroe
July 10, 2020 GTA Project No. 35200584
2 
Based on the topographic information provided on the Union County GIS, the ground
surface elevations across the site range from a high of approximate Elevation 515 feet above mean
sea level (AMSL), near the central portion of the subject property, to a low of approximate
Elevation 495 feet AMSL, along the western portion of the subject property. Please refer to the
attached Topographic Map presented as Figure 3 in Appendix A for more detailed information.
PROPOSED CONSTRUCTION
GTA was provided with a copy of a “Preliminary Site Plan” of the Equalization Basin
provided by the City of Monroe. The Plan indicates that the subject property is proposed to be
developed with an equalization basin in the center of the property that will be approximately 550
feet in length by 550 feet in width and approximately 6 feet deep. In addition, the Plan indicates
that 2 utility lines will be constructed; a 36-inch force main extending approximately 600 linear
feet along the western portion of the subject property to the WWTP, and a 24-inch return line
extending approximately 250 linear feet along the northern portion of the property to Richardson
Creek.
Detailed information regarding the site grading, slope embankment details, as well as inlet
and outlet structure information has not been provided to us at this time. However, based on our
site reconnaissance, we anticipate that general site grading may consist of cut depths on the order
of 6 feet and fill depths up to approximately 10 feet to establish final design grades for the
embankment.
SITE GEOLOGY
The site is located in the Charlotte Belt of the Piedmont Plateau Geologic Province.
According to the Geologic Map of North Carolina (1985), the site is underlain by metamudstone
and meta argillite (CZmd2) also known as the “Cid Formation”. Ground surface elevations within
the Piedmont Plateau vary from approximately 400 feet above sea level (AMSL) in the east to
2,000 feet (AMSL) in the west.
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The typical residual soil profile associated with the Charlotte Belt consists of fine-grained
soils (clays/silts) near the surface, where soil weathering is more advanced, underlain by more
coarse-grained soils (sandy silts/silty sands) with depth. The boundary between the soil and rock
is not sharply defined. This transitional zone, termed weathered rock, is normally found overlying
the parent bedrock. The degree of weathering is influenced by fractures, joints, and by the presence
of less resistant rock types. Therefore, the profile of the weathered rock and hard rock is quite
irregular and erratic, even over short horizontal distances. Lenses, boulders, hard rock, and zones
of weathered rock are often encountered within the soil mantle, well above the general
unweathered bedrock level.
The topography of the Piedmont Plateau consists of well-rounded hills and long rolling
ridges with a northeast-southwest trend. This rolling topography is the result of streams flowing
across and acting on rocks of unequal hardness. The Piedmont Plateau region is underlain by older
crystalline (metamorphic and igneous) rock formations that trend northeast-southwest and vary
greatly in their resistance to weathering and erosion. The major streams generally flow across the
rock structures that are more highly fractured and more prone to weathering. Please refer to the
publications for a more detailed description of the geologic units.
SUBSURFACE EXPLORATION
The field exploration consisted of drilling Standard Penetration Test (SPT) borings at
fifteen (15) locations, designated as B-1 through B-15, across the property. The soil test borings
were selected and field located by GTA using the existing topography and aerial photographs by
visual estimation. The approximate location of the soil test borings is shown on the attached
Exploration Location Plan presented as Figure 2 in Appendix A. Elevations provided on the boring
logs were interpolated from site topography provided by Union County GIS. Please note that the
boring locations have not been instrument surveyed and thus, all locations and elevations should
be considered approximate.
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The borings were drilled on June 17 and 18, 2020 to depths ranging from approximately
6.1 to 14 feet below the existing ground surface using an ATV-mounted CME 550X and ATV-
mounted D-50 drill rig provided by HPC. A dozer was required to clear a path to gain access to
the boring locations. Therefore, some topsoil was partially/completely removed in the vicinity of
the borings during the clearing process.
Standard Penetration Testing was performed in the boreholes, with soil samples obtained
at approximately 2½-foot intervals in the upper 10 feet and at 5-foot intervals thereafter. Standard
Penetration Testing involves driving a 2-inch O.D., 1 ⅜ -inch I.D. split-spoon sampler with a 140-
pound hammer free-falling 30 inches. The SPT N-value, given as blows per foot (bpf), is defined
as the total number of blows required to drive the sampler from 6 to 18 inches. Samples retrieved
from the borings were returned to GTA's laboratory for visual classification by laboratory
personnel. Descriptions as provided on the logs are visual.
Boring logs were prepared using the observations made in the field during drilling, as well
as the visual – manual classification in the laboratory. A geotechnical staff professional classified
each soil sample on the basis of color, texture, and plasticity characteristics in general accordance
with the USCS classification system. The geotechnical staff professional grouped the various soil
types into the major zones noted on the boring logs. The stratification lines designating the
interface between each material on the boring logs is approximate; the transition between the strata
may be gradual in both the vertical and horizontal directions.
SUBSURFACE CONDITIONS
The borings confirm the underlying geologic formation as metamudstone and meta argillite
(CZmd2). The test borings typically encountered native residual soils underlain by soft/hard
weathered rock. Beneath the topsoil layer in the borings, residual soils were encountered. The
residual soils generally consist of sandy silt. SPT N-values in the residual soils ranged from 7 to
77 blows per foot (bpf), averaging 38 bpf, indicating these soils are generally stiff to very hard in
consistency.
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Beneath the residual soils at Borings B-1 through B-15, soft weathered rock (SWR) was
encountered at depths ranging from approximately 1 to 13.5 feet below the existing ground surface.
In addition, a lens of SWR was encountered at Borings B-9 and B-14 at depths ranging from
approximately 3.5 to 5 feet. Based on the North Carolina Building Code, soft weathered rock is
defined as “broken and partially weathered rock with standard penetration resistance (ASTM D
1586) between 50 blows per 6 inches and 50 blows per inch.” SWR is a decomposed rock that
serves as the transitional zone between soil and rock. SWR is most commonly delineated from
residual soil when SPT values of 100 bpf are exhibited by the SPT sampler. While SWR is a rock-
like material, it is often visually classified as a sandy silt as the SPT sampler pulverizes the material
as it is driven.
Underlying the residual soils and/or SWR at Borings B-2 and B-3, hard weathered rock
(HWR) was encountered at a depth of approximately 6 feet below the existing ground surface.
Based on the North Carolina Building Code, hard weathered rock is defined as “broken and
partially weathered rock of sufficient hardness to refuse soils sampling tools; normally has
standard penetration resistance (ASTM D 1586) in excess of 50 blows per 1 inch.”
Borings B-1 through B-15 were terminated in the SWR/HWR upon auger refusal at depths
ranging from approximately 6.1 to 14 feet below the existing ground surface. Auger refusal is
defined as material that could not be penetrated with the drill rig equipment used on the project.
Auger refusal may be due to large boulders, rock ledges, lenses, seams, or the top of parent
bedrock. Core drilling techniques would be required to evaluate the character and continuity of
the refusal material. However, core drilling was beyond the scope of this study.
Groundwater was not encountered in the borings at the termination of drilling. Boring
cave-in depths ranged from approximately 4.7 to 12.1 feet below the existing ground surface. The
boring cave-in depths can be an indication of the groundwater level or may result from the soil
falling in as the augers are removed from the borehole upon completion. Please be advised that
groundwater levels are expected to fluctuate with changes in precipitation, drainage, and other
factors.
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LABORATORY TESTING
Recovered soil samples were transported to our laboratory where they were subjected to
visual - manual classification by a geotechnical staff professional. Boring Logs were prepared
using the observations made in the field during drilling, as well as the visual – manual classification
in the laboratory, supplemented by laboratory testing.
A sample obtained from Boring B-10 at a depth of 1 to 2.5 feet was tested in our laboratory
for Grain-Size Analysis, Atterberg Limits and natural moisture content. The Grain-Size Analysis
and Atterberg Limits testing were performed to determine the Unified Soil Classification System
(USCS) designation for the soil. The USCS classifications provide information regarding soil
engineering behavior. The results are below in Table 1 as well as in Appendix C:
TABLE 1: SUMMARY OF LABORATORY TESTING
Boring No. Depth (ft) USCS Classification LL PI Moisture
Content (%)
B-10 1.0 - 2.5 ML 45 13 15.3
Selected samples from the borings were tested in our laboratory for natural (in-situ)
moisture content. The tested samples from Borings B-1, B-3, B-5, B-8, B-11, and B-12 indicated
natural moisture contents ranging from 12.8 to 25.3 percent, with an average moisture content of
approximately 18 percent.
One bulk near-surface sample from Boring B-10 was tested for moisture-density
relationships in accordance with the Standard Proctor. The results of these tests are summarized
in Table 2. Please refer to the laboratory test data provided in Appendix C for further information.
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TABLE 2: SUMMARY OF COMPACTION DATA
Standard Proctor (ASTM D698)
Boring
No.
Depth
(ft)
Maximum
Dry Density
(pcf)
Optimum
Moisture
(%)
Natural
Moisture
(%)
B-10 1 – 2.5 104.7 20.5 15.5
PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS
Based upon the results of this study, it is our opinion that the proposed construction is
feasible, given that the geotechnical recommendations are followed, and that the standard level of
care is maintained during construction. Please note that the presence of weathered and/or
unweathered rock as well as moisture-sensitive soils wet of optimum for compaction will impact
the design and construction of the proposed development and associated costs. Please note,
depending upon the final grading and utility design, costs associated from the removal of
weathered and/or unweathered rock could be significant. A discussion of GTA's preliminary
assessment and conclusions with respect to the proposed construction is presented in the following
paragraphs.
As discussed, only conceptual plans have been provided at this time. This report is
intended to assist the client with preliminary feasibility and planning. When final mass
grading/development plans become available, it is recommended that additional explorations be
performed to further identify the limits and characteristics of the near-surface soils and soft/hard
weathered rock. Depending on final design grades and building layouts, geotechnical
recommendations should be developed for the design and construction of foundations and
parking/drive areas.
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1.Preliminary Foundation Support
In general, the proposed cast-in-place concrete structures including inlet and outlet
structures can be supported on shallow spread footings. The medium stiff to very hard and
medium dense to very dense native non-plastic soils are generally considered suitable for
support of foundations using an allowable bearing pressure of 2,500 pounds per square foot
(psf). Please note that higher allowable bearing pressures may be available if the
foundations are bearing on or near the soft/hard weathered rock. This should be further
evaluated in the field during final design of the foundations.
Exterior footings should be founded a minimum of 12 inches below final exterior grade to
provide protection from frost action. Depending upon the foundation bearing elevation,
some undercutting and/or recompaction of any soft or very loose near-surface soils should
be anticipated. Footings should be supported on stable medium stiff non-plastic natural
soils, or properly compacted structural fill as outlined in this report. New fill for support
of foundations should be placed in accordance with GTA’s site grading recommendations.
Any soft, disturbed, or unstable soil present at the footing subgrade elevation should be
excavated to a stable stratum. In addition, if rock is encountered at the foundation bearing
elevation, a minimum of 6-inches of #57 washed stone should be placed between the top
of the rock and the bottom of the foundation bearing elevation to provide a uniform
transition and prevent a “point load” condition on the footings. Over-excavation and
replacement, if required, should be performed under the observation of the project
geotechnical engineer or their qualified representative based on actual conditions
encountered in the field at the time of construction. Bearing capacity evaluations should
be performed using a combination of visual observation, hand-auger probing, and Dynamic
Cone Penetrometer (DCP) testing. Concrete placement should be performed the same day
the footings are excavated to prevent exposure and potential weakening of the foundation
subgrade.
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2.Site Grading for Embankments
Prior to the placement of fill, where required, the existing subgrade surface should be
stripped and grubbed to remove all existing trees, surface vegetation, topsoil/rootmat and
other deleterious matter. The stripping thickness will be dependent on a variety of factors,
including the soil moisture, construction traffic disturbance, weather during construction,
and contractor care.
As previously indicated, moisture contents from the various soil test borings ranged from
15.3 to 25.3 percent, with an average moisture content of approximately 18 percent. In
addition, the natural moisture content of the Proctor sample obtained at B-10 was 15.5
percent. Therefore, if plans are to reuse the excavation materials for structural fill, some
moisture conditioning of the soils should be anticipated, especially for moisture contents
greater than 23 percent. To minimize the economic impact associated with poor
workability and/or trafficability of wet subgrade soils due to moisture sensitive soils, GTA
recommends construction during the dry season (summer/fall) to reduce the effort and cost
required for drying of the wet soils. GTA recommends that a contingency be established
for drying and/or over-excavating, chemical treatment, and replacing unsuitable soils.
After stripping, the fill subgrade should be proof-rolled with a loaded, 10-wheel tandem-
axle dump truck. The proof-rolling should be observed by a geotechnical engineer or their
qualified representative. Any soft or otherwise unsuitable soils should be dried and re-
compacted or removed prior to placement of fill. No fill should be placed until the
subgrade is approved by the geotechnical engineer.
Off-site borrow, if required, should meet Unified Soil Classification System (USCS)
designation SM, SP, SW, GP, GM, or GW and be approved by the Geotechnical Engineer.
All fills should be constructed in maximum 8-inch thick loose lifts and be compacted to
the following specifications:
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COMPACTION SPECIFICATIONS
Structure / Fill Location Compaction / Moisture Specification
Below foundations, retaining walls,
inlet/outlet structures, and within wall
backfill or slopes steeper than 5H:1V
95% of ASTM D-698
Moisture: ± 3% of optimum
All compactive effort should be verified by in-place density testing. New fills constructed
on slopes steeper than 5H:1V (horizontal to vertical) should be keyed into existing slopes
for stability considerations. All fill slopes steeper than 5H:1V should generally be placed
as structural fill and be controlled and compacted to minimum densities as specified above.
Fill for slopes in non-structural areas, such as landscape berms, can be constructed as steep
as 3H:1V up to a height of ten feet.
Detailed information regarding the height and slope of the new embankments have not
been provided to us at this time. Depending on the height of the new embankment slopes,
a slope stability analysis should be performed prior to construction.
3.Difficult Excavation
As previously indicated, detailed information regarding the site grading and final design
grades have not been provided to us at this time. Based on the results of the field
exploration, it is GTA’s opinion that the majority of the excavations less than 5 feet below
the existing grades can be made by conventional means, i.e. scraping. However, results of
the borings indicate that soft/hard weathered rock (SWR/HWR) was encountered in Borings
B-1 through B-15 at depths ranging from approximately 1 to 13.5 feet below the existing
ground surface.
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The depth to, and thickness of the soft/hard weathered rock, rock lenses, seams, or bedrock,
can vary dramatically in short distances, especially between the boring locations. Therefore,
soft/hard weathered rock and/or bedrock should be anticipated during excavation in these
areas.
It has been our past experience in this geologic area, that materials having SPT ‘N’ values of
less than 50 blows per 4 inches can generally be excavated using pans and scrapers by first
loosening with a single tooth ripper attached to a suitable size dozer, such as a Caterpillar D-
8 or D-9. It should be noted that ripping is dependent on the equipment and techniques used
as well as the operator’s skill and experience. The success of the ripping operation is
dependent on finding the proper combination for the conditions encountered. Excavation of
the weathered rock is typically much more difficult in confined excavations, such as utility
excavations. Jack hammering or blasting should be anticipated for materials having SPT ‘N’
values in excess of 50 blows per 2 inches, or at or near the level that auger refusal is
encountered. Test pits should be performed prior to construction to determine whether these
materials can be excavated.
On projects requiring ripping or jack hammering, a controversy sometimes develops as to
whether the material can be removed by ripping or whether blasting is required. The project
specifications and contract should be carefully prepared to reduce the potential for disputes
and claims relating to excavation of very dense weathered or unweathered rock.
4.Subsurface Utilities
The natural soils are considered suitable for support of below grade utilities; however, GTA
recommends a minimum 6-inch-thick granular bedding to provide uniform support as
dictated by site conditions or as required by local code. Based upon the results of the
borings, GTA anticipates that the excavations may be accomplished using standard utility
construction equipment to a depth of up to approximately 5 feet below existing grades
throughout the majority of the site depending upon the excavator utilized. However, auger
refusal material was encountered in Borings B-1 through B-15 at depths ranging from
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approximately 6.1 to 14 feet below the existing ground surface. Jacking or blasting should be
anticipated below these depths.
After the utility alignments and elevations are designed and prior to construction, test pits
should be performed to determine if invert elevations can be achieved. Due to the potential
for collapse of unsupported excavations, the utility contractor should be prepared to
provide adequate earth support systems during utility construction.
Compaction of the soils to the degree specified in the Site Grading section of this report
may require that the soils be moisture conditioned prior to placement and compaction
within the trench. If the excavated materials are wet of the optimum moisture content, they
should be spread in thin layers and aerated by discing to within 2 to 4 percentage points of
the optimum moisture. If soils are not dried, suitable borrow material will need to be
imported from other areas of the site for utility trench backfill.
5. Surface and Subsurface Drainage
As previously indicated, detailed information regarding the site grading and final design
grades have not been provided to us at this time. However, final grades should be carefully
established to provide adequate surface drainage away from the foundations. A minimum
grade of 3 percent in landscape areas is recommended to direct surface water away from
the proposed structures.
Groundwater was not encountered in the borings at the termination of drilling. The
boreholes were backfilled at the termination of drilling for safety reasons. Please note that
groundwater levels are likely to fluctuate due to variation in rainfall and other factors. It
is GTA’s opinion that excavations to depths of 10 feet or less should not be impacted by
groundwater. However, groundwater may be encountered in excavations at greater depths,
especially along any low-lying portions of the site. There is also a potential for perched or
trapped groundwater to be encountered at shallow depths in localized portions of the site,
particularly within granular soil seams underlain by less permeable material or at
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fill/natural ground interfaces. In the event that localized perched water is encountered, the
contractor should be prepared to dewater the excavations.
ADDITIONAL SERVICES
We recommended that during construction of the subject project, a geotechnical engineer
be retained to provide observation and testing services for the following items.
Review final site and structural plans to evaluate if they conform with the intent
of this report.
If necessary, perform a design phase geotechnical exploration consisting of
additional borings and/or test pits to further evaluate the weathered and/or
unweathered rock on-site.
Observe and test the preparation of the equalization basin area.
Provide observation and testing during fill placement to evaluate if the work is
being performed in accordance with the project specifications and intent of this
report.
Observe the proof-rolling of fill subgrade in the embankment areas prior to
placing fill to evaluate stability.
LIMITATIONS
This report has been prepared for the exclusive use of the City of Monroe in accordance
with generally accepted geotechnical engineering practice. No warranty, express or implied, is
made. The analysis and recommendations contained in this report are based on the data obtained
from limited observation and testing of the surface materials. The borings indicate soil conditions
only at specific locations and times, and only to the depths penetrated. They do not necessarily
reflect strata variations that may exist between boring locations. Consequently, the analysis and
recommendations must be considered preliminary until the subsurface conditions can be verified
by direct observation at the time of construction. If variations in subsurface conditions from those
Report of Preliminary Exploration – 15 MG Equalization Basin City of Monroe
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described are noted during construction, recommendations in this report may need to be re-
evaluated.
In the event that any changes in the nature, design, or location of the facilities are planned,
the conclusions and recommendations contained in this report should not be considered valid
unless the changes are reviewed and conclusions of this report are verified in writing. GTA
Associates, Inc. is not responsible for any claims, damages, or liability associated with
interpretation of subsurface data or reuse of the subsurface data or engineering analysis without
the express written authorization of GTA Associates, Inc.
In accordance with the guidelines of Geoprofessional Business Association (GBA), it is
recommended that GTA Associates, Inc. be retained to provide continuous soils engineering
services for this project. Participation of GTA will facilitate compliance with GTA's
recommendations, and allow changes to be made in these recommendations, in the event that
subsurface conditions are found to vary from those anticipated prior to the start of construction.
This report and the attached logs are instruments of service. If certain conditions or items
are noted during our investigation, GTA Associates, Inc. may be required by prevailing statutes to
notify and provide information to regulatory or enforcement agencies. GTA Associates, Inc. will
notify our Client should a required disclosure condition exist.
This report was prepared by GTA Associates, Inc. (GTA) for the sole and exclusive use of
GTA Associates, Inc. and the City of Monroe. Use and reproduction of this report by any other
person without the expressed written permission of GTA or the City of Monroe is unauthorized
and such use is at the sole risk of the user.
35200584 GTA ASSOCIATES, INC.
Important lntormation about Your Geotechnical-Engineering Report Geotechnical Services Are Performed tor Specific Purposes, Persons, and Projects Geotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical-engineering study conducted for a civil engi­neer may not fulfill the needs of a construction contractor or even another civil engineer. Because each geotechnical-engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. No one except you should rely on your geotechnical engineering report without first conferring with the geotechnical engineer who prepared it. And no one-not even you -should apply the report for any purpose or projectexcept the one originally contemplated.Read the Full Report Serious problems have occurred because those relying on a geotechnical­engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotechnical-Engineering Report Is Based on a Unique Set ol Project-Specific Factors Geotechnical engineers consider many unique, project-specific factors when establishing the scope of a study. Typical factors include: the client's goals, objectives, and risk-management preferences; the general nature of the structure involved, its size, and configuration; the location of the struc­ture on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotech­nical engineer who conducted the study specifically indicates otherwise, do not rely on a geotechnical engineering report that was: •not prepared for you,•not prepared for your project,•not prepared for the specific site explored, or•completed before important project changes were made.Typical changes that can erode the reliability of an existing geotechnical­engineering report include those that affect: •the function of the proposed structure, as when it's changed from aparking garage to an office building, or from a light-industrial plantto a refrigerated warehouse,•elevation, configuration, location, orientation, or weight of theproposed structure,•composition of the design team, or•project ownership.As a general rule, always inform your geotechnical engineer of project changes--even minor ones-and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed. Subsurface Conditions Can Change A geotechnical-engineering report is based on conditions that existed at the time the study was performed. Do not rely on a geotechnica/-engineer­ing reportwhose adequacy may have been affected by: the passage of time; by man-made events, such as construction on or adjacent to the site; or by natural events, such as floods, droughts, earthquakes, or groundwa­ter fluctuations. Always contact the geotechnical engineer before applying the report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems. Most Geotechnical Findings Are Professional Opinions Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engi­neers review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ-sometimes significantly­from those indicated in your report. Retaining the geotechnical engineer who developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipated conditions. A Report's Recommendations Are Not Final Do not overrely on the construction recommendations included in your report. Those recommendations are not final, because geotechnical engi­neers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual
subsurface conditions revealed during construction. The geotechnicalengineer who developed your report cannot assume responsibility or liability for the report's recommendations if that engineer does not perform construction observation. A Geotechnical Engineering Report Is Subject to Misinterpretation Other design team members' misinterpretation of geotechnical-engineering reports has resulted in costly problems. Lower that risk by having your geo­technical engineer confer with appropriate members of the design team alter submitting the report. Also retain your geotechnical engineer to review perti­nent elements of the design team's plans and specifications. Contractors can also misinterpret a geotechnical-engineering report. Reduce that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing construction observation. Do Not Redraw the Engineer's Logs Geotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognizethat separating logs f ram the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give con­tractors the complete geotechnical-engineering report, but preface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure contrac­tors have sufficient time to perform additional study. Only then might you be in a position to give contractors the best information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Read Responsibility Provisions Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than other engineering disci­plines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled "limitations," many of these provisions indicate where geotechnical engineers' responsi­bilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvironmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform a geoenviron­mental study differ significantly from those used to perform a geotechnicalstudy. For that reason, a geotechnical-engineering report does not usually relate any geoenvironmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks orregulated contaminants. Unanticipated environmental problems have led tonumerous project failures. It you have not yet obtained your own geoenvi­ronmental information, ask your geotechnical consultant for risk manage­ment guidance. Do not rely on an environmental report prepared for some­one else.Obtain Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a com­prehensive plan, and executed with diligent oversight by a professional mold-prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, many mold-prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical-engineering study whose findings are conveyed in this report, the geotechnical engineer in charge of this project is not a mold-prevention consultant; none of the services per­
formed in connection with the geotechnica/ engineer's study
were designed or conducted for the purpose of mold preven­
tion. Proper implementation of the recommendations conveyed
in this report will not of itself be sufficient to prevent mold
from growing in or on the structure involved. Relyt. on Your GBA-Member Geotechncial Engineer for 11dditiona1 Assistance Membership in the GEOPROFESSIONAL BUSINESS AssOCIATION exposes geotech­nical engineers to a wide array of risk confrontaton techniques that can be of genuine benefit for everyone involved with a construction project. Confer with your GSA-member geotechnical engineer for more information. GEOPROFESSIONAL
BUSINESS
-ASSOCIATION
8811 Colesville Road/Suite G106, Silver Spring, MD 20910
Telephone: [phone] Facsimile: 301/589-2017
e-mail: [e-mail] www.geoprofessional.or g
Copyright 2014 by Geoprofessional Business Association, lnc.(GBA). Duplication. reproduction, or copying of this document, in whole or in part, by any means whatsoever. is strictly
prohibited, except with GBA's specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission
of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document as a complement to or as an element of a geotechnical-engineering
report. Any other firm, individual, or other entity that so uses this document without being a GBA member could be commiting negligent or intentional (fraudulent) misrepresentation.
IIGEA 0914/5.0MRP
APPENDIX A
FIGURES
Base map obtained from Google Maps
Monroe, Union County, North Carolina
2020
GTA ASSOCIATES, INC.
GEOTECHNICAL AND ENVIRONMENTAL CONSULTANTS
710 Peninsula Lane, Suite B
Charlotte, North Carolina 28273
Ph. [phone]
Fax [phone]
CITY OF MONROE WWTP EQ BASIN
SITE LOCATION PLAN
MONROE, NORTH CAROLINA
JOB NO: DATE: SCALE: DRAWN BY: REVIEWED BY: FIGURE NO:
35200770 JUNE 11, 2020 NTS GTA JPW 1
NAPPROXIMATE SITE
LOCATION
EXPLORATION LOCATION PLAN INDUSTRIAL DRIVE, MONROE, NC GTA ASSOCIATES 710 PENINSULA LANE, SUITE B CHARLOTTE, NC 28273 [phone] O(704) 553-2400 FDATE: June 11, 2020 FIGURE NO. 2 LEGEND: SOIL TEST BORING LOCATIONS
TOPOGRAPHIC PLAN MONROE WWTP EQ BASIN - INDUSTRIAL DRIVE, MONROE, NC GTA ASSOCIATES 710 PENINSULA LANE, SUITE B CHARLOTTE, NC 28273 [phone] O(704) 553-2400 FDATE: June 11, 2020 FIGURE NO. 2 LEGEND: SOIL TEST BORING LOCATIONS
APPENDIX B
BORING LOGS
Approximate Depth Approximate
Approximate Boring
Boring Depth of of Soft / Hard Depth of
Level of Cave-in Moisture
No. Boring Weathered Rock Auger Refusal
Groundwater Depths Content
(ft.)(ft.) (ft.)
Depth (ft) (ft.) (%) / (Depth)
B-1 7.4 6 7.4 Dry 4.7 16.1 (1-2.5')
B-2 6.1 1 6.1 Dry 5
B-3 6.1 6 6.1 Dry 5.2 15.3 (1-2.5')
B-4 6.4 4 6.4 Dry 5.1
B-5 9.9 9.5 9.9 Dry 6.9 21.5 (1-2.5')
B-6 6.2 4 6.2 Dry 4.7
B-7 6.4 4.5 6.4 Dry 4.8
B-8 9.3 9 9.3 Dry 6.8 12.8 (3.5-5')
B-9 9.9 4 9.9 Dry 6.8
B-10 14 13.5 14 Dry 12.1
B-11 9.8 9.5 9.8 Dry 6.8 17.2 (3.5-5')
B-12 6.7 6.5 6.7 Dry 5.6 25.3 (3.5-5')
B-13 6.8 4.5 6.8 Dry 4.8
B-14 9.8 4.5 9.8 Dry 7.8
B-15 7 4.5 7 Dry 4.6
TABLE 1
SUBSURFACE EXPLORATION SUMMARY
CITY OF MOROE WWTP EQUALIZATION BASIN
GTA JOB NO. 35200850
Page 1 of 1
NOTES FOR EXPLORATION LOGS
KEY TO uses TERMINOLOGY AND GRAPHIC SYMBOLS COARSE-GRAINED SOILS (GRAVEL AND SAND)
COARSE­GRAINED SOILS
MORE THAN 50% OF MATERIAL IS LARGER THAN NO. 200 SIEVE SIZE
FINE­GRAINED SOILS
MAJOR DIVISIONS SYMBOLS
(BASED UPON ASTM D 2488) GRAPHIC LETTER
GRAVEL AND GRAVELLY SOILS
)'-' \_J 0 CLEAN o[Y 00 GW GRAVELS 1,-,b ___ D <2:jrr_�-c------1.... w. (LESS THAN 15% PASSING THE NO. 200 SIEVE) ; I•�. '. MORE THAN 50% • • 1 .. t •OF COARSE GRAVELS WITH •

I
• , •
GP
GM FRACTION FINES • � ◄ I�. RETAINED ON NO. baP'l)lll .. ,.r,,,,:;,1------. 4 SIEVE (MORE THAN 15% PASSING THE NO. 200 SIEVE) �
SAND AND SANDY SOILS
MORE THAN 50% OF COARSE FRACTION PASSING ON NO. 4SIEVE
CLEAN SANDS
...... . . . . . ....... ............ ............ ....... . . . . .
(LESS THAN 15% PASSING THE NO. 200 SIEVE) :'..\';;::: :'( .. :.:.. .. ::·.-.::•:"
SANDS WITH FINES
···· .. ·.:� �., .. :
':··· -�
·
/\.; I •;•
7/27//2 (MORE THAN 15% PASSING THE NO. 200 SIEVE) �
SILTS AND LEAN CLAYS SILT OR CLAY • ------
GC
SW
SP
SM
SC
ML
CL
(<15% RETAINED ON THE NO. 200 SIEVE) LIQUID LIMIT LESS THAN50 ---OL ---SILT OR CLAY WITH SAND OR GRAVEL f-------��-r+------1 MORE THAN 50% o o OF MATERIAL IS (151/o TO 301/o RETAINED ON THE NO. 200 SIEVE)MH SMALLER THAN SANDY OR GRAVELLY SILT OR CLAY ELASTIC SILTSNO. 200 SIEVE AND ��..»:M,:;t-------t S (>30% RETAINED ON THE NO. 200 SIEVE) CH IZE FAT CLAYS
LIQUID LIMIT ////"..'/
HIGHLY ORGANIC SOILS
GREATER THAN 50 f./f}.f.1/} '{f ///.1/f./. / ·//. OH
PT
BLOWS PER DESIGNATION FOOT(BPF) "N"
VERY LOOSE 0-4
LOOSE 5 -10
MEDIUM DENSE 11 -30
DENSE 31 -50
VERY DENSE >50
NOTE: "N" VALUE DETERMINED AS PER ASTM D 1586
FINE-GRAINED SOILS (SILT AND CLAY)
CONSISTENCY BPF "N"
VERY SOFT <2
SOFT 2-4
MEDIUM STIFF 5-8
STIFF 9-15
VERY STIFF 16-30
HARD >30
NOTE: ADDITIONAL DESIGNATIONS TO ADVANCE SAMPLER INDICATED IN BLOW COUNT COLUMN: WOH = WEIGHT OF HAMMER WOR = WEIGHT OF ROD(S)
SAMPLE TYPE
DESIGNATION SYMBOL
NOTE: DUAL SYMBOLS ARE USED TO INDICATE COARSE-GRAINED SOILS WHICH CONTAIN AN ESTIMATED 5 TO 15% FINES BASED ON
VISUAL CLASSIFICATION OR BETWEEN 5 AND 12% FINES BASED ON LABORATORY TESTING; AND FINE-GRAINED SOILS WHEN THE PLOT
OF LIQUID LIMIT & PLASTICITY INDEX VALUES FALLS IN THE PLASTICITY CHART'S CROSS-HATCHED AREA. FINE-GRAINED SOILS ARE
CLASSIFIED AS ORGANIC (OL OR OH) WHEN ENOUGH ORGANIC PARTICLES ARE PRESENT TO INFLUENCE ITS PROPERTIES.
LABORATORY TEST RESULTS ARE USED TO SUPPLEMENT SOIL CLASSIFICATION BY THE VISUAL-MANUAL PROCEDURES OF ASTM D 2488.
SOIL SAMPLE
SHELBY TUBE
S-
U-ADDITIONAL TERMINOLOGY AND GRAPHIC SYMBOLS
DESCRIPTION
TOPSOIL
ADDITIONAL DESIGNATIONS MAN MADE FILL
GLACIAL TILL
COBBLES AND BOULDERS
DESCRIPTION "N"VALUE
RESIDUAL SOIL HIGHLY WEATHERED ROCK 50 TO 50/1" DESIGNATIONS
MORE THAN 50 BLOWS FOR 1" PARTIALLY WEA THE RED ROCK OF PENETRATION OR LESS,
AUGER PENETRABLE
GRAPHIC SYMBOLS
� ... \f�-.-3:,,:.:,\·i;: ·,
;_
1:r:��r:/(0
X X X )( XXX X �f -£ xA )<, )<, )(.}<, XJV' -· � .:.i. 00 .oo .oo .oo ,! 0 ! 0 ! 0 ! �
�:;:4/{f;,;:;4,i\�: 1iI!f:�l��
� b. b. b. b.
b. b. b. b. /j
IA A A A A
ROCK CORE R-
WATER DESIGNATION
DESCRIPTION SYMBOL
ENCOUNTERED DURING DRILLING �
UPON COMPLETION OF DRILLING �
24 HOURS AFTER COMPLETION y
NOTE: WATER OBSERVATIONS WERE MADE AT THE TIME INDICATED. POROSITY OF SOIL STRATA, WEATHER CONDITIONS, SITE TOPOGRAPHY, ETC. MAY CAUSE WATER LEVEL CHANGES.
REVISED JUNE 2009
0
5
10
15
20
25
30
S-1
S-2
S-3
0.4
3.5
6.0
16
16
14
4-7-17
7-15-22
17-22-50/5
24
37
100+
506.0
505.6
500.0
498.6
ML
SWR
Topsoil (5")
Brown, moist, very stiff, sandy SILT
same, hard
Brown, dry, hard, Soft Weathered Rock
BORING TERMINATED AT 7.4 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-1
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):4.7
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:506
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME 550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-1SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
M.C.=16.1%
0
5
10
15
20
25
30
S-1
S-2
S-3
0.5
3.5
6.0
8
2
.5
28-50/6
50/3
50/1
100+
100+
100+
500.0
499.5
494.0
493.9
SWR
HWR
Topsoil (6")
Gray, dry, hard, Soft Weathered Rock
same
Gray, dry, hard, Hard Weathered Rock
BORING TERMINATED AT 6.1 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-2
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):5.0
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:500
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME 550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-2SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
0
5
10
15
20
25
30
S-1
S-2
S-3
0.8
3.5
6.0
16
16
1
6-7-8
6-13-22
50/1
15
35
100+
498.0
497.2
492.0
491.9
ML
HWR
Topsoil (8")
Brown, moist, stiff, sandy SILT
same, hard
Brown, dry, hard, Hard Weathered Rock
BORING TERMINATED AT 6.1 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-3
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):5.2
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:498
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME 550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-3SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
M.C.=15.3%
0
5
10
15
20
25
30
S-1
S-2
S-3
0.6
3.5
6.0
16
5
.5
6-8-18
28-50/5
50/4
26
100+
100+
495.0
494.4
491.5
488.6
ML
SWR
Topsoil (7")
Brown, moist, very stiff, sandy SILT
Brow, dry, hard, Soft Weathered Rock
same
BORING TERMINATED AT 6.4 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-4
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):5.1
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:495
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME 550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-4SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
0.2
3.5
6.0
8.5
13
16
16
16
6-8-14
13-23-34
30-36-38
22-31-50/5
22
57
74
100+
514.0
513.8
505.5
504.1
ML
SWR
Topsoil (2")
Brown, moist, very stiff, sandy SILT
same, hard
same
Brown, dry, hard, Soft Weathered Rock
BORING TERMINATED AT 9.9 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-5
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):6.9
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:514
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME 550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-5SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
M.C.=21.5%
0
5
10
15
20
25
30
S-1
S-2
S-3
0.5
3.5
6.0
10
6
2
4-4-27
21-50/4
50/2
31
100+
100+
504.0
503.5
500.5
497.8
ML
SWR
Topsoil (5")
Brown, moist, hard, sandy SILT
Brown, dry, hard, Soft Weathered Rock
same
BORING TERMINATED AT 6.2 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-6
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):4.7
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:504
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME 550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-6SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
0
5
10
15
20
25
30
S-1
S-2
S-3
0.5
3.5
6.0
15
16
3
9-11-10
35-27-50/5
50/5.5
21
100+
100+
512.0
511.5
508.5
505.6
ML
SWR
Topsoil (6")
Tan, moist, very stiff, sandy SILT
Tan, dry, hard, Soft Weathered Rock
same
BORING TERMINATED AT 6.4 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-7
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):4.8
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:512
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME 550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-7SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
0.0
3.5
6.0
8.5
16
14
16
3
7-9-11
16-22-43
17-33-44
27-50/3
20
65
77
100+
511.0
502.5
501.7
ML
SWR
Tan, moist, very stiff, sandy SILT
same, hard
same
Tan, dry, hard, Soft Weathered Rock
BORING TERMINATED AT 9.3 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-8
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):6.8
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:511
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME 550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-8SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
M.C.=12.8%
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
0.3
3.5
6.0
8.5
16
9
5
13
3-4-3
19-50/5
20-33-29
7-30-50/5
7
100+
62
100+
509.0
508.7
505.5
503.0
500.5
499.1
ML
SWR
ML
SWR
Topsoil (3")
Red, moist, medium stiff, sandy SILT
Red, dry, hard, Soft Weathered Rock
Brown, moist, hard, sandy SILT
Brown, dry, hard, Soft Weathered Rock
BORING TERMINATED AT 9.9 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-9
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-17-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):6.8
DATE STARTED:6-17-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-17-20 GROUND SURFACE ELEVATION:509
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:D-50T
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-9SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
S-5
0.3
3.5
6.0
8.5
13.5
18
16
18
17
4
6-9-11
16-27-26
12-21-29
18-22-30
50/6
20
53
50
52
100+
512.0
511.7
498.5
498.0
ML
SWR
Topsoil (3")
Brown, moist, very stiff, sandy SILT
same, hard
same
same
Brown, dry, hard, Soft Weathered Rock
BORING TERMINATED AT 14.0 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-10
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-17-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):12.1
DATE STARTED:6-17-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-17-20 GROUND SURFACE ELEVATION:512
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:D-50T
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-10SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
0.3
3.5
6.0
8.5
16
16
18
13
8-11-23
16-23-36
32-31-39
18-34-50/4
34
59
70
100+
512.0
511.7
503.5
502.2
ML
SWR
Topsoil (3")
Brown, moist, hard, sandy SILT
same
same
Brown, dry, hard, Soft Weathered Rock
BORING TERMINATED AT 9.8 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-11
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-17-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):6.8
DATE STARTED:6-17-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-17-20 GROUND SURFACE ELEVATION:512
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:D-50T
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-11SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
M.C.=17.2%
0
5
10
15
20
25
30
S-1
S-2
S-3
0.6
3.5
6.0
10
10
6
4-4-5
4-6-9
45-50/3
9
15
100+
512.0
511.4
506.0
505.3
ML
SWR
Topsoil (7")
Brown, moist, stiff, sandy SILT
same
Brown, dry, hard, Soft Weathered Rock
BORING TERMINATED AT 6.7 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-12
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):5.6
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:512
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-12SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
M.C.=25.3%
0
5
10
15
20
25
30
S-1
S-2
S-3
0.5
3.5
6.0
16
14
8
11-14-28
13-45-50/3
50/4
42
100+
100+
510.0
509.5
506.5
503.2
ML
SWR
Topsoil (5")
Brown, moist, hard, sandy SILT
Brown, dry, hard, Soft Weathered Rock
same
BORING TERMINATED AT 6.8 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-13
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):4.8
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:510
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-13SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
0
5
10
15
20
25
30
S-1
S-2
S-3
S-4
0.5
3.5
6.0
8.5
18
15
17
12
7-11-19
18-34-50/6
28-45
14-20-50/4
30
100+
45
100+
506.0
505.5
502.5
500.0
497.5
496.2
ML
SWR
ML
SWR
Topsoil (5")
Brown, moist, very stiff, sandy SILT
Brown, dry, hard, Soft Weathered Rock
Brown, moist, hard, sandy SILT
Brown, dry, hard, Soft Weathered Rock
BORING TERMINATED AT 9.8 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-14
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):7.8
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:506
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-14SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
0
5
10
15
20
25
30
S-1
S-2
S-3
0.3
3.5
6.0
4
16
10
2-3-4
15-42-50/6
34-50/5
7
100+
100+
506.0
505.7
502.5
499.0
ML
SWR
Topsoil (4")
Brown, moist, medium stiff, sandy SILT
Brown, dry, hard, Soft Weathered Rock
same
BORING TERMINATED AT 7.0 FEET UPON AUGER
REFUSAL
LOG OF BORING NO. B-15
PROJECT:City of Monroe WWTP WATER LEVEL (ft):DRY
DATE:6-18-20PROJECT NO.: 35200850
PROJECT LOCATION: Industrial Drive, Monroe, N.C.CAVED (ft):4.6
DATE STARTED:6-18-20 WATER ENCOUNTERED DURING DRILLING (ft)DRY
DATE COMPLETED:6-18-20 GROUND SURFACE ELEVATION:506
DRILLING CONTRACTOR:HPC DATUM:AMSL
DRILLER:Zack Kiker EQUIPMENT:CME550X
DRILLING METHOD:Hollow Stem Auger LOGGED BY:A.B.
SAMPLING METHOD:Standard Penetration Testing CHECKED BY:J.P.W.
NOTES:GROUND SURFACE ELEVATIONS ARE APPROXIMATE BASED ON TOPOGRAPHIC SURVEY
LOG OF BORING NO. B-15SAMPLENUMBERSAMPLEDEPTH (ft.)SAMPLERECOVERY (in.)SAMPLEBLOWS/6 inchesN (blows/ft.)ELEVATION (ft.)DEPTH (ft.)USCSGRAPHICSYMBOLDESCRIPTION REMARKS
Sheet 1 of 1
Sheet 1 of 1
APPENDIX C
LABORAOTRY RESULTS
ASTM Specifications performed may include: D421, D422, D2216, D2217, and D4318.Tested By: SC Checked By:
MOISTURE DENSITY RELATIONSHIP TEST REPORT
Dry density, pcf89
94
99
104
109
114
Water content, %
7 12 17 22 27 32 37
20.5%, 104.7 pcf
ZAV for
Sp.G. =
2.68
Test specification:ASTM D 698-91 Procedure B Standard
S-1 ML 15.5 2.68 45 13 1 60
(ML) Red Orange SANDY SILT.
35200850 City of Monroe
7/9/20
Elev/Classification Nat.Sp.G. LL PI
% > % <
Depth USCS AASHTO Moist.3/8 in. No.200
TEST RESULTS MATERIAL DESCRIPTION
Project No.Client:Remarks:
Project:
Date:
Location: B-10 Sample Number: 1
Figure
Maximum dry density = 104.7 pcf
Optimum moisture = 20.5 %
Monroe WWTP
Hazen and Sawyer • 9101 Southern Pine Blvd, Suite 250 • Charlotte, NC 28273 • 704.357.3150
Technical Memorandum 32138-012July 2, 2020
To: Russell Colbath, Director of Water Resources
From: Jarrod Karl, Senior Principal Scientist
Jim Struve, Vice President
Re: Natural Resources Technical Memorandum
Monroe WWTP Flow Equalization Basin
Monroe, Union County, North Carolina
The purpose of this technical memorandum is to document potential Waters of the United States, Waters of
the State and federally-protected threatened or endangered species at the location of the proposed Flow
Equalization (EQ) Basin adjacent to the Monroe Wastewater Treatment Plant (WWTP). The location of the
proposed basin is immediately adjacent to the WWTP site, separated by a small perennial stream (Joes
Branch). Hazen Staff (Jim Struve and Jarrod Karl) met with Kyle Ketchum on June 25, 2020 to review the
proposed project area in the field prior to walking the site and conducting field investigation of potential
waters, habitats and species. The following sections summarize the methods and results for the desktop and
field investigations.
Preliminary Desktop Assessment
Methods
Hazen performed a preliminary desktop assessment to collect background information related to wetlands,
waters and protected species prior to conducting the on-site field investigation. To determine the potential
presence of streams, wetlands and open waters in the proposed project area, Hazen consulted the United
States Geological Survey National Map (TNM)1, the United States Fish and Wildlife Service National
Wetlands Inventory (NWI) Wetlands Mapper2 and United States Department of Agriculture - Natural
Resources Conservation Service Web Soil Survey (WSS)3 maps pertaining to the proposed project area. To
determine the potential presence of protected species or critical habitat in the proposed project area, Hazen
consulted the United States Fish and Wildlife Service (USFWS) Endangered and Threatened Species and
Species of Concern by County for North Carolina4 online database for Union County and Natural Heritage
Element Occurrence (NHEO) Geographic Information System (GIS) shapefiles5. To determine the presence
of historic or cultural resources, Hazen consulted the North Carolina State Historic Preservation Office’s
HPOWEB 2.0 web application6.
1 United States Geological Survey, The National Map. https://viewer.nationalmap.gov/basic/.
2 United States Fish and Wildlife Service, Wetlands Mapper. https://www.fws.gov/wetlands/Data/Mapper.html.
3 United States Department of Agriculture, Natural Resources Conservation Service, Web Soil Survey.
https://websoilsurvey.nrcs.usda.gov/.
4 United States Fish and Wildlife Service, Raleigh Field Office. Endangered and Threatened Species and Species of
Concern by County for North Carolina. https://www.fws.gov/raleigh/species/cntylist/union.html.
5 North Carolina Natural Heritage Program, Natural Heritage Element Occurrence Shapefiles. Updated April, 2020.
6 North Carolina Historic Preservation Office, HPOWEB 2.0.
https://nc.maps.arcgis.com/home/item.html?id=d2d04d8d7e03403f889419526e682529.
ATTACHMENT 5
July 2, 2020
Monroe WWTP Flow Equalization Basin Page 2 of 2
Results
Maps reviewed for the presence of potential wetlands and waters indicated the presence of two streams,
Richardson Creek and Joes Branch, that border the proposed project area to the north and east, respectively.
A potential stream channel was identified on the western border of the proposed project area. No hydric soils
or wetlands were indicated. The list of protected species for Union County indicates the potential presence of
one endangered mussel species (Carolina heelsplitter (Lasmigona decorata)) and two endangered plant
species (Michaux’s sumac (Rhus michauxii) and Schweinitz’s sunflower (Helianthus schweinitzii)). Based
on a review of the GIS shapefiles for protected species, there are no records of federally protected species in
the project area. One state-listed significantly rare mussel (eastern creekshell (Villosa delumbis)) may be
present in Richardson Creek. No historic or cultural resources were identified.
On-Site Field Investigation
Methods
Hazen Staff walked upland areas, drainageways, and floodplains within and adjacent to the project area to
determine the presence of wetlands, streams and suitable habitat for protected species. Photographs of the
site were taken to document existing conditions at the time of the investigation.
Results
Two perennial streams (Richardson Creek and Joes Branch) border the proposed project area. No other
streams, open waters or wetlands were identified in or adjacent to the proposed project area. Habitat within
the proposed project area includes forested upland areas with dense tree canopy and floodplain areas that are
frequently flooded. Photographs of the site are located in Appendix A.
Conclusions
The proposed project is expected to result in impacts to one perennial stream (Joes Branch) due to
construction of a force main connecting the proposed EQ basin to the existing WWTP. Impacts to
Richardson Creek are not anticipated. No Michaux’s sumac or Schweinitz’s sunflower plants or suitable
habitats are present in proposed project area. These two species typically occupy disturbed areas or open
woods with an abundance of sunlight. The forested upland areas present in the proposed project area do not
provide the sunlight required to support the two species due to the dense tree canopy. The floodplain areas
do not support the two species due dense tree canopy and frequent flooding. Richardson Creek is not
expected to be impacted by the proposed project, therefore direct impacts to the eastern creekshell should not
occur. Indirect impacts to Richardson Creek resulting from downstream sedimentation during construction
are possible. Therefore, Hazen recommends consultation with the United States Army Corps of Engineers
prior to construction to determine potential requirements.
Qualifications of the Investigator
Jarrod Karl is a Senior Principal Scientist in Hazen’s Charlotte Office. He has a Bachelor of Science in
Environmental Studies from the University of North Carolina at Asheville and has 23 years of experience
conducting natural resources assessments, including stream and wetland delineations and endangered species
evaluations. Prior to joining Hazen in 2015, Mr. Karl spent 13 years working for Charlotte-Mecklenburg
Storm Water Services where he oversaw the City’s Section 401-404 permitting program and stream and
wetland mitigation bank.
July 2, 2020
Monroe WWTP Flow Equalization Basin A-1
Appendix A: Photographs
hazenandsawyer.com
PHOTOGRAPHS
Monroe WWTP Flow Equalization Basin
Monroe, Union County, North Carolina
Photo 1. Typical view of upland forested areas with dense tree canopy.
Photo 2. View of recent clearing to conduct geotechnical explorations.
1
2
hazenandsawyer.com
PHOTOGRAPHS
Monroe WWTP Flow Equalization Basin
Monroe, Union County, North Carolina
Photo 3. Upstream view of Joes Branch, a perennial tributary to Richardson
Creek. Joes Branch and adjacent areas near the confluence with Richardson
Creek are inundated by flooding during large storm events.
Photo 4. View of narrow floodplain area and sanitary sewer right-of-way adjacent
to Richardson Creek. A steep slope is present at the edge of the right-of-way.
The floodplain is shaded by tree canopy and frequently floods.
3
4
1
Attachment 6
Attachment 7