WQ0002708_Modification_20221121

Initial Review
Reviewer Thornburg, Nathaniel D
Is this submittal an application? (Excluding additional information.)*
Yes No
Permit Number (IR) * WQ0002708
Applicant/Permittee City of Raleigh
Applicant/Permittee Address PO Box 590 Raleigh, NC 27602
Is the owner in BIMS? Yes NO Is the facility in BIMS? Yes No
Owner Type Municipal
Facility Name Wrenn Road WWTF
County Wake
Fee Category Fee Amount $0
Is this a complete application?*
Yes No
Signature Authority
Signature Authority Title
Signature Authority Email
Document Type (if non -application)
Email Notifications
Does this need review by the hydrogeologist? * Yes NO
Regional Office
CO Reviewer
Admin Reviewer
Complete App Date 11/21/2022
Below list any additional email address that need notification about a new project.
... ... ..
Email Address
Comments to be added to email notfication
Comments for Admin
Comments for RO

Comments for Reviewer
Comments for Applicant

Submittal Form
Project Contact Information
Please provide information on the person to be contacted by NDB Staff regarding electronic submittal, confirmation of receipt, and other correspondence.
............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Name* Marla Dalton
Email Address*
[e-mail]
Project Information
Application/Document Type*
New (Fee Required)
Modification - Major (Fee Required)
Renewal with Major Modification (Fee
Required)
Annual Report
Additional Information
Other
Phone Number*
9197967843
Modification - Minor
Renewal
GW-59, NDMR, NDMLR, NDAR-1,
N DAR-2
Residual Annual Report
Change of Ownership
We no longer accept these monitoring reports through this portal. Please click on the link below and it will take you to the correct form.
hftps://edocs.deq.nc.gov/Forms/NonDischarge_Monitoring_Report
Perm it Type:*
Wastewater Irrigation
High -Rate Infiltration
Other Wastewater
Reclaimed Water
Closed -Loop Recycle
Residuals
Single -Family Residence Wastewater
Other
Irrigation
Permit Number: *
WQ0002708
Has Current Existing permit number
Applicant/Permittee*
City of Raleigh
Applicant/Permittee Address*
PO Box 590 Raleigh, NC 27602
Facility Name*
Wrenn Road WWTF
Please provide comments/notes on your current submittal below.
Raleigh Water would like to request a minor modification of the Wrenn Road Facility Surface
Irrigation Permit WQ0002708. A study was previously performed to determine background
Manganese (Mn) in the groundwater wells at this facility. The value identified as the
background value for Mn exceeded the current permit limit of 0.05 mg/L. In a letter from Scott
Vinson (RRO, NCDEQ) received in June of 2022 it was agreed that 0.057 mg/L Mn should be
the limit in Attachment A of Permit WQ0002708. Please modify Attachment A to reflect 0.057
mg/L Mn.
At this time, paper copies are no longer required. If you have any questions about what is required, please contact Nathaniel Thornburg
at [e-mail].
Please attach all information required or requested for this submittal to be reviewed here.
(Application Form, Engineering Plans, Specifications, Calculations, Etc.)
15-WQ0002708 City of Raleigh Wrenn Road Groundwater
64.97MB
Monitoring Results Memorandum 9.13.2021_package.pdf
Upload only 1 PDF document (less than 250 MB). Multiple documents must be combined into one PDF file unless file is larger
than upload limit.
* By checking this box, I acknowledge that I understand the application will not be
accepted for pre -review until the fee (if required) has been received by the Non -
Discharge Branch. Application fees must be submitted by check or money order and
made payable to the North Carolina Department of Environmental Quality (NCDEQ).
I also confirm that the uploaded document is a single PDF with all parts of the
application in correct order (as specified by the application).
Mail payment to:
NCDEQ — Division of Water Resources
Attn: Non -Discharge Branch
1617 Mail Service Center

Raleigh, NC 27699-1617
Signature
0 owl
Submission Date 11/21/2022

From:
Dalton, Marla
To:
Thornbura. Nathaniel
Cc:
Joseph. Lisa
Subject:
[External] Minor Modification Wrenn Road WQ0002708
Date:
Monday, November 21, 2022 11:02:00 AM
CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as an
attachment to Report Spam.
Nathaniel -
Raleigh Water would like to request a minor modification of the Wrenn Road Facility Surface
Irrigation Permit WQ0002708. A study was previously performed to determine background
Manganese (Mn) in the groundwater wells at this facility. The value identified as the background
value for Mn exceeded the current permit limit of 0.05 mg/L. In a letter from Scott Vinson (RRO,
NCDEQ) received in June of 2022 it was agreed that 0.057 mg/L Mn should be the limit in
Attachment A of Permit WQ0002708. Please modify Attachment A to reflect 0.057 mg/L Mn.
Please let me know if you have any questions.
Thank you,
Marla Dalton
Non -Discharge Superintendent
Resource Recovery Division
Raleigh Water
(0) 919.996.3672
(M) 919.796.7843

Groundwater
Monitoring Results
Memorandum
Wrenn Road Facility
City of Raleigh
Garner, NC
September 13, 2021

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ii

Table of Contents
Introduction ............................................................................................................................. 1
Sampling Plan Review............................................................................................................. 2
Monitoring Well Installation................................................................................................... 2
Sample Collection and Methods ........................................................................................... 4
Results.................................................................................................................................... 5
Results Summary................................................................................................................. 5
Arsenic Results ................................................................................................................ 5
Iron Results ...................................................................................................................... 6
Manganese Results.......................................................................................................... 7
Conclusions ............................................................................................................................ 8

List of Tables
Table 1. Background Monitoring Well Summary ....................................................................... 2
Table 2. Background Monitoring Well Results for Arsenic (November 2019 – March 2021) ....... 5
Table 3. Background Monitoring Well Results for Iron (November 2019 – March 2021) ............. 6
Table 4. Background Monitoring Well Results for Manganese (November 2019 – March 2021) . 7

List of Figures
Figure 1. Background and Compliance Monitoring Wells .......................................................... 3
Figure 2. Iron Results .............................................................................................................. 6
Figure 3. Manganese Results .................................................................................................. 7

Appendices
Appendix 1 – Sampling and Data Analysis for Background Concentrations of As, Fe, and Mn in
Groundwater (2021)
Appendix 2 – Ground Water Monitoring Plan (2019)
Appendix 3 – Wrenn Road Monitoring Well Installation Report (2019)
Appendix 4 – Complete Groundwater Monitorin g Results

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1

Introduction
The Wrenn Road Facility is located in Garner, NC, and currently receives water treatment
process residuals from the Dempsey E. Benton (DE Benton) Water Treatment Plant (WTP).
Liquid residuals are received through a 16 -inch influent force main and spray -applied to the
site’s 14 irrigation zones, which are spread among over 600 acres of fields and woodlands.
Historically, the facility disposed of treated wastewater from the Garne r wastewater treatment
plant (WWTP). The facility has been operated by Raleigh Water since the merger of Garner’s
water and wastewater utilities with the City of Raleigh (City) in 2001, and stopped receiving
waste from the sewer system in 2008 when wastewater flow was permanently redirected to the
Neuse River Resource Recovery Facility (NRRRF).
A comprehensive hydrogeologic and geochemical evaluation was performed in 2010 to evaluate
the site as part of the permit modification applicati on1, 2. This study included the installation of
over 20 temporary piezometers and three monitoring wells, in addition to groundwater flow,
groundwater transport, and geochemical modeling. The two main purposes of the study were to:
1. Evaluate conditions before the DE Benton WTP residuals application , and
2. Identify recommended loading rates to the spray fields that would meet water quality
levels established in the modified permit.
The spray irrigation system and accompanying permit (WQ0002708) were modified to accept
DE Benton WTP residuals in 2012. As part of this permit, North Carolina Department of
Environmental Quality (NC DEQ) included the condition that the City prepare a monitoring plan
to assess if background concentrations of arsenic, iron, and manganese were above the levels
established in 15A NCAC 02L (referred to as “2L Standards”), which are as follows:
• Arsenic: 10 micrograms per liter (µg/L)
• Iron: 300 µg/L
• Manganese: 50 µg/L
Another goal of this sampling effort was to recommend site -specific background concent rations
for these constituents that are either the existing 2L Standards or higher concentrations if data
from the background samples is statistically greater than the standard. Data from the 2010
study was not used to establish background values because t he wells were not permanent , and
their sampling may not have met the currently recommended sampling methodology for metals.
This memorandum provides an overview of the results obtained from the groundwater
monitoring wells. A complete analysis of the resu lts of the monitoring efforts , including a
statistical analysis, is provided in Appendix 1, Sampling and Data Analysis for Background
Concentrations of As, Fe, and Mn in Groundwater (Eagle Resources, P.A., 2021). This
memorandum also briefly summarizes monitoring well installation and the sampling plan.

1 Soil and Environmental Consultants, 2009, Site Analysis for Wrenn Road Wastewater Treatment Plant Spray Irrigation System, Garner, Wake County, North Carolina.
2 Eagle Resources, P.A. May 10, 2010, Groundwater Mounding Analysis and Groundwater Quality Ass essment Wrenn Road Wastewater Treatment Plant Spray Irrigation
System, Garner, Wake County, North Carolina.

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2

Sampling Plan Review
Future groundwater monitoring cannot be performed using the piezometers installed during the
2010 study since these piezometers were only designed to be temporary and have since be en
abandoned. The three monitoring wells are not adequate in number or location to use for the
establishment of background concentrations. Therefore, a groundwater sampling plan was
developed and four new background monitoring well locations were identified with approval from
NC DEQ between February of 2017 and February of 2019. The complete sampling p lan is
provided in Appendix 2, Ground Water Monitoring Plan (2019).
This sampling plan included information related to the following:
• Installation and development of four (4) background monitoring wells at the Wrenn Road
Facility,
• Establishment of samplin g duration and sample collection protocols,
• Measurement of water quality parameters (iron, manganese, and arsenic ) bi-monthly,
• Determination of whether the 2010 sampling data are from the same population as
2019/2020 data, and its use in defining background statistics for groundwater
monitoring,
• Establishment of well maintenance protocols to ensure future resampling of wells can
occur, if necessary.
Monitoring Well Installation
Four (4) background monitoring wells were ins talled in August of 2019 . Background monitoring
well information is summarized in Table 1, including geographic coordinates, installation dates,
and depths. Figure 1 was developed by Eagle Resources, P.A. and presents a map of
background and monitoring well locations. Well locations were selected using model analyses
performed by Eagle Resources, P.A. and based on access requirements due to the
development of the adjacent residential subdivision. Wells were drilled and completed with
depths that extended at least into the Partially Weathered Rock (PWR) that lies beneath the soil
and saprolite. Additional information related to well installation can be found in the Wrenn Road
Background Monitoring Well Installation Report (2019), which is provided in Appendix 3.
Table 1. Background Monitoring Well Summary
Well
Name Easting Northing Installation
Date
Depth from Land
Surface (ft)
Screened
Intervals (ft)
PMW-1 2126151.11 691215.39 8/13/2019 43 33 to 43
PMW-2 2124505.08 691694.17 8/14/2019 20 10 to 20
PMW-3 2121970.60 688486.31 8/26/2019 16 6 to 16
PMW-4 2125522.18 687848.49 8/13/2019 74 64 to 74

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Figure 1. Background and Compliance Monitoring Wells

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Sample Collection and Methods
The Ground Water Monitoring Plan (2019) provided in Appendix 2 describes the sample
collection and methods followed during this project in detail. Groundwater samples were
collected from each monitoring well on the same day during each sampling event. Before
collecting groundwater samples, monitoring wells we re purged at a low flow until turbidity
reaches < 10 NTU or did not vary by more than 10%, and until pH and water temperature
measurements were stable. One duplicate sample was collected from one of the background
monitoring wells during each sampling event to evaluate consistency in field sampling meth ods
and laboratory analytical methods .
The first background monitoring well samples were collected in November of 2019 and
monitoring well sampling continued every other month for six months (January of 2020 and
March of 2020). Groundwater samples were measured by Raleigh Water staff in the field for pH,
conductivity, turbidity, and temperature . Laboratory parameters for samples collected through
November of 2020 were measured in the Raleigh Water laboratory for iron, manganese, and
arsenic. Iron, manganese, and arsenic samples collected in March of 2021 were analyzed by an
external laboratory.
The 2019 and 2020 sampling results were compared to results from 2010 sampling events to
evaluate any water quality changes that may have occurred . If these sampling results were
deemed statistically similar to the 2010 results, the 2019/2020 results could be combined with
2010 results to serve as the background iron, manganese, and arsenic concentrations. If the
results from the two sets of samples were statistically different, then only the 2019/2020 results
would be used.
The sampling dates for bi-monthly sampling were as follows:
• November 21, 2019
• January 17, 2020
• March 12, 2020
After the completion of bi-monthly monitoring well sampling, b ackground well monitoring
continued using the same schedule used by Raleigh Water for existing compliance well
monitoring. Sampling has occurred in April, August, and November of 2020 and in March of
2021 to evaluate data trends in iron, manganese, and arsenic.
The dates for these sampling events are as follows:
• April 14, 2020
• August 20, 2020
• November 4, 2020
• March 10, 2021

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Results
T he purpose of this section is to provide an overview of arsenic, iron, and manganese results.
The complete analysis of arsenic, iron, and manganese results is documented in Appendix 1,
Sampling and Data Analysis for Background Concentrat ions of As, Fe, and Mn in Groundwater
(2021), provided by Eagle Resources, P.A., and includes a statistical analysis to determine if
data are similar to those obtained in 2010.
During each sampling event, a log sheet was used to record sampling information (sample
collector(s), date/time, and weather condition(s)), field data (depth to water, total well depth,
volume of water purged before collecting the sample, turbidity, pH, temperature, and
conductivity), and laboratory data (iron, manganese, and arsenic). Complete groundwater
monitoring results are provided in Appendix 4.
Results Summary
Table 2, Table 3, and Table 4 present arsenic, iron and manganese results, respectively, from
six sampling events occurring from Novembe r of 2019 to March of 2021. Many parameters were
below detection limits.
Arsenic Results
Arsenic was below detection limit s in each of the groundwater monitoring well samples collected
from November of 2019 through March of 2021 , as shown in Table 2. In samples collected from
November of 2019 through November of 2020, the detection limit was 10 µg/L, which is also the
2L Standard. The arsenic detection limit was 5 µg/L for sample collected in March of 2021 due
to the use of an external laboratory. Since data were below detection , a statistical analysis was
not performed using arsenic data, and a time trend could not be developed .
Table 2. Background Monitoring Well Results for Arsenic (November 2019 – March 2021)
Well
Arsenic (µg/L) – Detection Limit: 10 µg/L (November of 2019 through
November of 2020) or 5 µg/L (March of 2021) – 2L Standard: 10 µg/L
Nov
2019
Jan
2020
Mar
2020
April
2020
Aug
2020
Nov
2020
March
2021
PMW-1 < 10 < 10 < 10 < 10 < 10 < 10 < 5
PMW-2 < 10 < 10 < 10 < 10 < 10 < 10 < 5
PMW-3 < 10 < 10 < 10 < 10 < 10 < 10 < 5
PMW-4 < 10 < 10 < 10 < 10 < 10 < 10 < 5

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Iron Results
Table 3 and Figure 2 present iron results from November of 2019 to March of 2021. Iron levels
were often below the detection limits. Samples collected from November of 2019 to November
of 2020 were analyzed using a method detection limit of 60 µg/L, whereas the sample collected
in March of 2021 was analyzed using a method detectio n limit of 50 µg/L. Iron was detected in
one sample collected from PMW-1, with a value of 97 µg/L (March of 2021). Iron was detected
in two samples collected from PMW-2, with value s of 72 µg/L (November of 2020) and 199 µg/L
(March of 2021). Iron levels only exceed ed the 2L Standard of 300 µg/L in two samples, both
collected from PMW-3 (August of 2020 and March of 2021). There is a statistically significant
increase in iron in PMW-3, and there is a statistically significant decrease in iron in PMW -4,
which is described in detail in Sampling and Data Analysis for Background Concentrations of
As, Fe, and Mn in Groundwater (Appendix 1).
Table 3. Background Monitoring Well Results for Iron (November 2019 – March 2021)
Well
Iron (µg/L) – Detection Limit: 60 µg/L (November of 2019 through November of
2020) or 50 µg/L (March of 2021) – 2L Standard: 300 µg/L
Nov
2019
Jan
2020
Mar
2020
April
2020
Aug
2020
Nov
2020
March
2021
PMW-1 < 60 < 60 < 60 < 60 < 60 < 60 97
PMW-2 < 60 < 60 < 60 < 60 < 60 72 199
PMW-3 199 < 60 141 < 60 482 73 601
PMW-4 172 68 < 60 < 60 69 < 60 < 50

Figure 2. Iron Results
0
100
200
300
400
500
600
700
No
v
-
1
9
De
c
-
1
9
Fe
b
-
2
0
Ma
r
-
2
0
Ma
y
-
2
0
Ju
l
-
2
0
Au
g
-
2
0
Oc
t
-
2
0
De
c
-
2
0
Ja
n
-
2
1
Ma
r
-
2
1
Ir
o
n

(
µ
g
/
L
)
Date
PMW-1 PMW-2 PMW-3 PMW-4 2L Standard

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Manganese Results
Table 4 and Figure 3 present manganese results from November of 2019 to March of 2021.
Manganese levels were below detection in many samples collected from PMW-2 and PMW-3.
Samples collected from November of 2019 to November of 2020 were analyzed using with a
method detection limit of 50 µg/L, whereas the sample collected in March of 2021 was analyzed
using a method detection limit of 10 µg/L. Manganese exceeded the 2L Standard of 50 µg/L in
each sample collected from PMW-1, one sample collected from PMW-3 (March of 2021), and a
majority of samples collected from PMW-4. There is no statistically significant increase in
manganese in monitoring wells, which is described in detail in Sampling and Data Analysis for
Background Concentrations of As, Fe, and Mn in Groundwater (Appendix 1).
Table 4. Background Monitoring Well Results for Manganese (November 2019 – March 2021)
Well
Manganese (µg/L) – Detection Limit: 50 µg/L (November of 2019 through
November of 2020) or 10 µg/L (March of 2021) – 2L Standard: 50 µg/L
Nov
2019
Jan
2020
Mar
2020
April
2020
Aug
2020
Nov
2020
March
2021
PMW-1 90 74 64 70 88 59 71
PMW-2 < 50 < 50 < 50 < 50 < 50 < 50 16
PMW-3 < 50 < 50 < 50 < 50 < 50 < 50 176
PMW-4 134 < 50 88 96 123 88 71

Figure 3. Manganese Results
0
20
40
60
80
100
120
140
160
180
200
No
v
-
1
9
De
c
-
1
9
Fe
b
-
2
0
Ma
r
-
2
0
Ma
y
-
2
0
Ju
l
-
2
0
Au
g
-
2
0
Oc
t
-
2
0
De
c
-
2
0
Ja
n
-
2
1
Ma
r
-
2
1
Ma
n
g
a
n
e
s
e

(
µ
g
/
L
)
Date
PMW-1 PMW-2 PMW-3 PMW-4 2L Standard

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Iron and manganese results were used to develop p robability curves and conduct an Analysis of
Variance Analysis (ANOVA). These exercises were conducted by Eagle Resources, P.A. to
determine if iron or manganese measured from November of 2019 through March of 2021 were
statistically similar to the results obtained in 2010. Based on this analysis, the data from the
2010 stud y is not statistically from the same population as the data from the compliance and
new background wells and should not be used in assessing site -specific background standards .
Conclusions
Arsenic levels remained below the detection limit s of 10 µg/L (thr ough November of 2020) and 5
µg/L (March of 2021) throughout the monitoring efforts conducted as part of this study.
Therefore, there is no statistical reasoning for setting a site -specific standard for arsenic greater
than the 2L Standard of 10 µg/L.
Data from the 2010 iron and manganese study and results reported as part of the November of
2019 to March of 2020 sampling are not statistically from the same population. Therefore, the
2010 data should not be used to assess site -specific background standards for iron and
manganese.
Iron levels were below detection in a majority of samples and exceeded the 2L Standard in two
samples (PMW-3, August of 2020 and March of 2021). Since the distributions for iron samples
are less than the 2L Standard of 300 µg/L, the 2L Standard should be used for compliance
purposes based on the data obtained to date. However, iron levels have changed over time in
some of the compliance and backgro und wells since the start of compliance sampling in
November of 2019. Therefore, it is recommended to continue assessing iron levels on an
annual basis to determine if the iron standard for the site should be increased to a value greater
than the 2L Standard in the future.
Manganese levels were below detection in many samples, but above the detection limit and 2L
Standard in each of the samples collected from PMW-1 and PMW-4 and one sample collected
from PMW-3 (March of 2021). Additionally, the average mang anese concentration was 66 µg/L,
which is greater than the 2L standard of 50 µg/L; therefore, it is recommended that the site -
specific background concentration for manganese be set at 6 6 µg/L.

1

Sampling and Data Analysis for Background Concentrations of
As, Fe, and Mn in Groundwater
Wrenn Road Wastewater Treatment Facility, Garner, NC

Prepared for:

HDR Engineering, Inc. of the Carolinas
and
City of Raleigh Public Utilities Department

March 18, 2021
Updated July 27, 2021

Eric G. Lappala, P.E.

Eagle Resources, P.A
215 West Moore Street
Southport, NC 28461
919-345-1013
www.eagleresources.com

i

Table of Contents
Introduction ....................................................................................................................................... 1
Installation of new Background Monitoring Wells .............................................................................. 1
Sampling of Background and Compliance Wells ................................................................................. 3
Data Analysis ..................................................................................................................................... 4
Probability Plots ........................................................................................................................................... 4
Analysis of Variance ..................................................................................................................................... 9
Pooling of new samples and the 2010 samples ........................................................................................... 12
Time Trends ................................................................................................................................................ 13
Conclusions ...................................................................................................................................... 17
Attachment 1 Approved Background Sampling Program .................................................................. 18
Attachment 2 Sampling Reports from CORPUD ................................................................................ 19

Figures

Figure 1.-- Location of compliance and background wells and wells and piezometers sampled for the
2010 report. .................................................................................................................................................. 2
Figure 2.-- Cumulative probability plots for the log-transformed concentrations of Fe for background
samples and 2010 report unfiltered samples. .............................................................................................. 5
Figure 3.-- Cumulative probability plots for concentrations of Fe for background samples and 2010
report filtered samples. ................................................................................................................................ 6
Figure 4.-- Cumulative probability plots for concentrations of Fe in compliance wells and new
background wells. ........................................................................................................................................ 7
Figure 5.-- Cumulative probability plots for concentrations of Mn for background samples and 2010
report filtered samples. ................................................................................................................................ 7
Figure 6.-- Cumulative probability plots for concentrations of Mn for background samples and 2010
report filtered samples. ................................................................................................................................ 8
Figure 7.-- Cumulative probability plots for concentrations of Mn from compliance and new background
wells. ............................................................................................................................................................ 9
Figure 8.-- Time trend in Fe and Mn in compliance well MW-B3. .......................................................... 13
Figure 9.-- Time trend in Fe and Mn in compliance well MW-B9. .......................................................... 14
Figure 10.-- Time trend in Fe and Mn in new background well PMW-3. ................................................ 15
Figure 11.-- Time trend in Fe and Mn in new background well PMW-4. ................................................ 16

ii
Tables
Table 1.-- Results of laboratory analyses for As, Fe, and Mn from the background and compliance wells
sampled in 2019 and 2020. .......................................................................................................................... 3
Table 2.-- Results of laboratory analyses for As, Fe, and Mn from wells and piezometers reported in the
2010 report. .................................................................................................................................................. 4
Table 3.-- One-way ANOVA comparing the 2020 background values for Fe to the values for unfiltered
samples from 2010. ..................................................................................................................................... 9
Table 4.-- One-way ANOVA comparing the 2020 background values for Fe to the values for filtered
samples from 2010. ................................................................................................................................... 10
Table 5.-- One-way ANOVA comparing the 2020 background values for Fe from the compliance wells
and the new background wells. ................................................................................................................. 10
Table 6.-- One-way ANOVA comparing the 2020 background values for Mn to the values for unfiltered
samples from 2010. ................................................................................................................................... 11
Table 7.-- One-way ANOVA comparing the 2020 background values for Mn from the compliance wells
and the new background wells. ................................................................................................................. 11
Table 8.-- One-way ANOVA comparing the values for Mn from the compliance wells vs. the new
background wells. ...................................................................................................................................... 12
Table 9.-- Regression analysis for the significance of the slope of the regression line for Fe in MW-B3.
................................................................................................................................................................... 13
Table 10.-- Regression analysis for the significance of the slope of the regression line for Fe in MW-B9.
................................................................................................................................................................... 14
Table 11.-- Regression analysis for the significance of the slope of the regression line for Fe in PMW-3.
................................................................................................................................................................... 15
Table 12.-- Regression analysis for the significance of the slope of the regression line for Fe in PMW-4.
................................................................................................................................................................... 16
Table 13.-- Regression analysis for the significance of the slope of the regression line for Mn in PMW-4.
................................................................................................................................................................... 16

1

Introduction
This report documents the methodology recommended in the approved monitoring plan1, and changes to
that methodology and the reasons for same to determine the statistically valid background concentrations
of Fe and Mn at the Wrenn Road Site. This update includes the results from samples collected on
03/10/2021 which concludes the approved sampling period.

The methodology is summarized as follows:

• Install new monitoring wells to assess concentrations of As, Fe and Mn that are hydraulically up
gradient or cross gradient from any field area to which treated effluent has been or may be applied.
• Sample the new wells and the three existing compliance wells (MW-B3, MW-B8m and MW-B9)
bi-monthly for one year using the purging and turbidity testing protocol specified in the approved
plan to reduce or eliminate high-turbidity samples (background samples).
• Compare the laboratory-determined concentrations of the three constituents in background
samples with the ones from samples collected from monitoring wells and temporary piezometers
as reported in the 2010 site investigation report2 to answer the following questions:

1. Are concentrations of the three constituents from the background samples statistically same as
those in Table 8 of the 2010 report (unfiltered samples)?
2. Are the filtered sample concentrations of the three constituents in Table 9 of the 2010 report
statistically the same as those from the background samples?
3. Are concentrations of the three constituents from the background samples from the new wells
from the same population as those from the three compliance wells?

• Based upon the answers to these questions, recommend a site-specific background concentration
for all three constituents that is either the existing NC 2L groundwater standard or a higher
concentration if data from the background samples is statistically greater than the standard.

Installation of new Background Monitoring Wells
The monitoring plan called for the installation and development of five (5) new background monitoring
wells. Owing to the availability of suitable background locations only four background wells (PMW-1,
PMW-2, PMW-3 and PMW-4) were approved by NC DEQ and installed as shown in Figure 1. The
installation details, turbidity testing during development and hydraulic conductivity testing of these wells
was documented in our 2019 letter report3 which is included as Attachment 1 to this report.

Figure 1 also shows the location of wells and piezometers from which samples were analyzed for As,
Fe, and Mn as documented in the 2010 site investigation report. Where two piezometers are shown at
the same location they were completed at different depths. Note that MW-3 will be removed as the result
of the construction of the I-540 corridor.

1 Eagle Resources, P.A.: Final_Groundwater_Baseline_Quality_Monitoring_Rev_020317
2 Eagle Resources, P.A.: Groundwater Mounding Analysis and Groundwater Quality Assessment, Wrenn Road Wastewater
Treatment Plant Spray Irrigation System, Garner, Wake County, North Carolina 10, 2010
3 Eagle Resources, P.A.: Documentation of Background Monitoring Well Installation and Testing, Letter Report to HDR
dated 11/08/19

2

Figure 1.-- Location of compliance and background wells and wells and piezometers sampled for the 2010 report.

3

Sampling of Background and Compliance Wells
The monitoring plan recommended that the background and compliance wells (MW-B3, MW-B8 and
MW-B9) be sampled bi-monthly for one year following the installation and development of the new
wells. The sampling was to follow the recommended procedure for low flow purging and field analysis
for pH, conductivity, turbidity and temperature. Samples taken were to be analyzed in the City of Raleigh
Public Utilities Department (CORPUD) laboratory for As, Fe and Mn. One duplicate sample was to be
taken from a randomly selected background well each sampling round.

CORPUD staff obtained the samples from the background and compliance wells using the protocol
recommended in the monitoring plan and submitted the samples to the CORPUD laboratory. The results
of these analyses are summarized in Table 1 and the sampling reports are included as Attachment 2 to
this report. Note that duplicate analyses are only available for the last three sampling rounds (8/20/20,
11/4/20 and 3/10/21).

Table 2 shows the values for As, Fe, and Mn from Tables 8 and 9 of the 2010 report.

Table 1.-- Results of laboratory analyses for As, Fe, and Mn from the background and compliance wells sampled in 2019 and 2020.

MW-B3 MW-B8 MW-B9 PMW-1 PMW-2 PMW-3 PMW-4 PMW-1 Dup
ug/l ug/l ug/l ug/l ug/l ug/l ug/l ug/l
11/5/19 <10 <10 <10 <10 <10 <10 <10 ns
1/17/20 <10 ns ns <10 <10 <10 <10 ns
3/12/20 <10 <10 <10 <10 <10 <10 <10 ns
4/14/20 <10 0 0 0 ns ns <10 ns
7/8/20 <10 <10 <10 ns ns ns ns ns
8/20/20 <10 ns na <10 <10 <10 <10 <10
11/4/20 <10 <10 <10 <10 <10 <10 <10 <10
3/10/21 < 5 ns ns < 5 < 5 < 5 < 5 < 5
11/5/19 180 76 82 <60 <60 199 172 ns
1/17/20 98 ns ns <60 <60 <60 68 ns
3/12/20 <60 <60 89 <60 <60 141 <60 ns
4/14/20 65 ns ns <60 <60 <60 <60 ns
7/8/20 234 <60 166 ns ns ns ns ns
8/20/20 118 ns ns <60 <60 482 69 <60
11/4/20 301 <60 135 <60 72 73 <60 <60
3/10/21 108 ns ns 97 ns ns ns 132
11/5/19 <50 <50 <50 90 <50 <50 134 ns
1/17/20 <50 ns ns 74 <50 <50 <50 ns
3/12/20 <50 <50 <50 64 <50 <50 88 ns
4/14/20 <50 ns ns 70 <50 <50 96 ns
7/8/20 <50 <50 <50 ns ns ns ns ns
8/20/20 <50 ns ns 88 <50 <50 123 90
11/4/20 <50 <50 <50 59 <50 <50 88 61
3/10/21 < 10 ns ns 71 16 176 71 71
Notes: ns = no sample collected.
Constituent Date
As
Fe
Mn

4

Table 2.-- Results of laboratory analyses for As, Fe, and Mn from wells and piezometers reported in the 2010 report.
Data Analysis
Because all the values for As were below the method detection limit of 10 µg/l for all samples, no statistical
analysis was performed for this constituent. To perform the analyses on Fe and Mn using all values from
the background samples that were less than the laboratory reported detection limits (10 µg/l for Mn and
60 µg/l for Fe) value of one (1) µg/l less that the limits was assigned (49 µg/l for Mn and 59 µg/l for Fe).

To answer the three questions posed previously, the concentrations of As, Fe, and Mn were compared by:
• Examination of plots of their log probability distributions; and
• Using One-Way Analysis of Variance (ANOVA)
Both statistical measures were computed using Microsoft Excel™.

Probability Plots
The cumulative probability distributions of the log-transformed (ln or log base e) for Fe and Mn for the
background samples (compliance wells plus background wells), for the 2010 unfiltered samples and for
the 2010 filtered samples were computed and plotted for visual comparison.

Figure 2 shows the probability curves for Fe in the background samples and for the 2010 unfiltered
samples. This comparison shows that the Fe samples from the 2010 report are not from the same
Filtered Filtered Filtered
Round 1 Round 2 Round 2 Round 1 Round 2 Round 2 Round 1 Round 2 Round 2
ug/l ug/l ug/l ug/l ug/l ug/l ug/l ug/l ug/l
MW-1 42 8 < 50 11742 4157 16 1067 220 26
MW-2 8 ns ns 6369 ns ns 628 ns ns
MW-3 8 < 50 < 50 42 2497 39 371 ns 101
PZ-1 68 10 < 50 3834 799 130 ns 1812 1676
PZ-2 61 11 < 50 11694 2324 12 ns 443 91
PZ-3 9 ns ns 3024 ns ns ns ns ns
PZ-4 24 < 50 < 50 26276 921 78 4432 339 331
PZ-5 82 < 50 < 50 30202 153 8 4114 52 43
PZ-6 24 < 50 < 50 69147 28581 22710 561 1628 1968
PZ-7 111 6 < 50 23603 1709 77 2163 144 47
PZ-8 61 < 50 < 50 31936 272 17 3160 21 19
PZ-9 24 ns ns 6921 ns ns 3460 ns ns
PZ-10 16 < 50 < 50 6958 578 22 3238 106 85
PZ-11 < 50 ns ns 1406 ns ns 428 ns ns
PZ-12 31 < 50 < 50 10303 512 38 842 38 32
PZ-14 ns ns ns 1523 ns ns 553 ns ns
PZ-15 ns ns ns 684 ns ns 20 ns ns
PZ-16 6 ns ns 2388 ns ns 250 ns ns
PZ-17 16 ns ns 2294 ns ns ns ns ns
PZ-18 42 < 50 < 50 6160 606 103 334 37 51
PZ-19 6 ns ns 3140 ns ns 220 ns ns
ns = no sample collectred
Unfiltered
Mn
Well
Unfiltered
As
Unfiltered
Fe

5
population as the background samples. Fe concentrations for both sets of samples are approximately log-
normally distributed based on the apparent fit of the curves to the data points.

Figure 2.-- Cumulative probability plots for the log-transformed concentrations of Fe for background samples and 2010 report unfiltered
samples.
Figure 3 shows the probability curves for Fe in the background samples and for the 2010 filtered samples.
This comparison shows that the filtered Fe samples from the 2010 report are closer to the same population
as the background samples but still probably not equal. Fe concentrations for both sets of samples are
approximately log-normally distributed based on the apparent fit of the curves to the data points.

6

Figure 3.-- Cumulative probability plots for concentrations of Fe for background samples and 2010 report filtered samples.

Figure 4 shows the probability curves for Fe in the background samples from the new background wells
and from the compliance wells. This comparison shows that Fe from the compliance wells and from the
new wells are from the same population and therefore can be pooled. Because the distributions for the
pooled samples for Fe are less than the 2L standard, the 2L standard of 300 µg/l should be used for
compliance purposes to establish the site-specific background value of Fe concentrations for both sets of
samples are approximately log-normally distributed based on the apparent fit of the curves to the data
points.

7

Figure 4.-- Cumulative probability plots for concentrations of Fe in compliance wells and new background wells.
Figure 5 shows the probability curves for Mn in the background samples and for the 2010 unfiltered
samples. This comparison shows that the Mn samples from the 2010 report are not from the same
population as the background samples. Mn concentrations for both sets of samples are approximately
log-normally distributed based on the apparent fit of the curves to the data points.

Figure 5.-- Cumulative probability plots for concentrations of Mn for background samples and 2010 report filtered samples.

8
Figure 6 shows the probability curves for Mn in the background samples and for the 2010 filtered
samples. This comparison shows that the filtered Mn samples from the 2010 report are closer to the same
population as the background samples but still probably not equal. Mn concentrations for both sets of
samples are approximately log-normally distributed based on the apparent fit of the curves to the data
points.

Figure 6.-- Cumulative probability plots for concentrations of Mn for background samples and 2010 report filtered samples.
Figure 7 shows the probability curves for Mn in the background samples from the new background wells
and from the compliance wells. This comparison shows that Mn from the compliance wells and from the
new wells are approximately from the same population but the compliance well data is skewed by all
being at the detection limit of 50 µg/l. Mn concentrations for both sets of samples are approximately
log-normally distributed based on the apparent fit of the curves to the data points.

The mean of the distributions for Mn when all data from the background and compliance wells are
considered is less than the 2L standard because of the large number of values less than the detection
concentration of 50 µg/l. Therefore, if the data from all of these wells is considered, the 2l standard of
50 µg/l should be used for compliance purposes.

However, if only PMW-1 and PMW-4 are used to establish the site -specific background concentration of
Mn, there is statistical support for increasing it. The mean Mn value for all samples from these two wells
is 86 µg/l and the standard deviation is 22 µg/l. If only these two wells are used, it is recommended that
the site-specific background concentration be set at 80 µg/l.

The large number of non-detect concentrations of Mn in the compliance wells is likely the result of dilution
by historical irrigation applied to their up-gradient fields. The non-detect values of Mn in PMW-2 and
PMW-3, which are located cross-gradient from all sprayfields, is likely the result of dilution from surface
runoff and flow in the stream located between them and the sprayfields.

9

Figure 7.-- Cumulative probability plots for concentrations of Mn from compliance and new background wells.

Analysis of Variance
One-way Analysis of Variance (ANOVA) on the log-transformed values to further assess whether the new
background results from the compliance and background wells are from the same population as the 2010
samples. The analyses were conducted using the Data Analysis Package for Microsoft Excel™.

Table 3 shows the ANOVA for Fe between the background samples and the unfiltered 2010 samples.
Because the F-statistic value of 8.85 is greater than the Fcrit value of 3.96, the samples are not from the
same population, consistent with the probability plot analysis.

Table 3.-- One-way ANOVA comparing the 2020 background values for Fe to the values for unfiltered samples from 2010.
Groups Count Sum Average Variance
ln Fe Background Samples 46 237.64 5.17 29.83
ln Fe 2010 Unfiltered Samples 38 322.25 8.48 20.95
Source of Variation SS df MS F P-value F crit
Between Groups 228.5736 1 228.57 8.85 0.00 3.96
Within Groups 2117.4 82 25.82
Total 2345.973 83
Fe Background + Compliance Wells vs 2010 Unfiltered Samples
Anova: Single Factor Alpha = 0.01
ANOVA

10
Table 4 shows the ANOVA for Fe between the background samples and the filtered 2010 samples.
Because the F-statistic value of 0.14 is less than the Fcrit value of 4.00, the samples are from the same
population, consistent with the probability plot analysis and may be pooled.

Table 4.-- One-way ANOVA comparing the 2020 background values for Fe to the values for filtered samples from 2010.
Table 5 shows the ANOVA for Fe between the samples from the new background wells and the
compliance wells for the 2019-2020 background sampling period. Because the F-statistic value of 2.11is
less than the Fcrit value of 4.11, the samples are from the same population, consistent with the probability
plot analysis and may be pooled.

Table 5.-- One-way ANOVA comparing the 2020 background values for Fe from the compliance wells and the new background wells.
Table 6 shows the ANOVA for Mn between the background samples and the unfiltered 2010 samples.
Because the F-statistic value of 2.36 is slightly less than the Fcrit value of 3.97, the samples are from the
same population, consistent with the probability plot analysis.

Groups Count Sum Average Variance
ln Fe Background Samples 46 237.64 5.17 29.83
ln Fe 2010 Filtered Samples 17 79.05 4.65 9.27
Source of Variation SS df MS F P-value F crit
Between Groups 3.30 1 3.30 0.14 0.71 4.00
Within Groups 1490.62 61 24.44
Total 1493.93 62
Anova: Single Factor Alpha = 0.01
Fe Background + Compliance Wells vs 2010 Filtered Samples
ANOVA
Groups Count Sum Average Variance
ln Fe Compliance Wells 12 54.93 4.58 0.34
ln Fe Background Wells 26 111.98 4.31 0.26
Source of Variation SS df MS F P-value F crit
Between Groups 0.60 1 0.60 2.11 0.16 4.11
Within Groups 10.27 36 0.29
Total 10.87 37
Fe Background Wells vs Compliance Wells
Anova: Single Factor Alpha = 0.01
ANOVA

11

Table 6.-- One-way ANOVA comparing the 2020 background values for Mn to the values for unfiltered samples from 2010.
Table 7 shows the ANOVA for Mn between the background samples and the filtered 2010 samples.
Because the F-statistic value of 1.93 is less than the Fcrit value of 4.05, the samples are from the same
population, consistent with the probability plot analysis and may be pooled. The differences between the
two populations are the result of assigning a value of 49 µg/l. to samples that were reported to be below
the detection limit of 50 µg/l.

Table 7.-- One-way ANOVA comparing the 2020 background values for Mn from the compliance wells and the new background wells.
Table 8 shows the ANOVA for Mn between the samples from the new background wells and the
compliance wells for the 2019-2020 background sampling period. Because the F-statistic value of 5.95
is close to the Fcrit value of 4.09, the samples probably are from the same population, consistent with the
probability plot analysis and may be pooled. The differences between the two populations are the result
of assigning a value of 49 µg/l to samples that were reported to be below the detection limit of 50 µg/l.
Groups Count Sum Average Variance
ln Mn Background 46 220.72 4.80 30.17
ln Mn 2010 Unfiltered 33 216.32 6.56 18.07
Source of Variation SS df MS F P-value F crit
Between Groups 59.32 1 59.32 2.36 0.13 3.97
Within Groups 1936.00 77 25.14
Total 1995.32 78
Mn Background + Compliance Wells vs 2010 Unfiltered Samples
Anova: Single Factor Alpha = 0.01
ANOVA
Groups Count Sum Average Variance
ln Mn Background 33 216.32 6.56 18.07
ln Mn 2010 Filtered 16 79.48 4.97 5.66
Source of Variation SS df MS F P-value F crit
Between Groups 27.1682947 1 27.17 1.93 0.17 4.05
Within Groups 663.187462 47 14.11
Total 690.355756 48
Anova: Single Factor Alpha = 0.01
ANOVA
Mn Background + Compliance Wells vs 2010 Filtered Samples

12

Table 8.-- One-way ANOVA comparing the values for Mn from the compliance wells vs. the new background wells.

Pooling of new samples and the 2010 samples
The monitoring plan recommended that if samples from the background sampling were statistically from
the same population as those from the 2010 study that they should be pooled to determine if they should
be used to set site-specific background concentrations for Fe and Mn.

Because the statistical analyses in the foregoing show that the 2011 unfiltered sample results for both Fe
and Mn are not from the same population as those from the background monitoring program samples to
date the 2011 unfiltered samples should not be used in an assessment of a site-specific background
standard for either Fe or Mn.

The filtered samples from 2011 for both Fe and Mn appear to approximately from the same population
as the background monitoring program samples. This is likely because purging and sampling protocol
used for the background program accomplished the same reduction in turbidity and suspended fine
particulate matter as filtration did for the 2010 samples. Because filtration of samples is not included in
the accepted sampling and analysis protocol by NC DEQ, it is recommended that the 2010 filtered
sample data not be used in assessing site-specific background standards for either constituent.
Groups Count Sum Average Variance
ln Mn Compliance Wells 11 42.81 3.89 0.00
ln Mn Background Wells 30 123.77 4.13 0.10
Source of Variation SS df MS F P-value F crit
Between Groups 0.44 1 0.44 5.95 0.02 4.09
Within Groups 2.89 39 0.07
Total 3.33 40
Mn Background vs Compliance Wells
Anova: Single Factor Alpha = 0.01
ANOVA

13
Time Trends
The monitoring plan recommended sampling the new background wells for one year on the same
schedule used for the compliance wells (March, July, and November) to evaluate any time trends
in As, Fe, Mn to consider in compliance assessments. The values plotted and analyzed below are
not log-transformed as the conclusions reached regarding the significance of the slope of the
trend lines is not affected by the transformation. Plots are only included for those wells in
which the number of sample results greater than the detection limits for either Fe or Mn provided
for a meaningful analysis.

Figure 8 and Table 9 show that there is no statistically significant increase in Fe in MW-B3
because the F -statistic value of 0.42 shown in Table 9 is less than the Significance F value of
0.54.

Figure 8.-- Time trend in Fe and Mn in compliance well MW-B3.

Table 9.-- Regression analysis for the significance of the slope of the regression line for Fe in MW-B3.

0
50
100
150
200
250
300
350
0 100 200 300 400 500
[F
e
]

&

[
M
n
]
,

u
g
/
l
Days since 11/01/2019
Fe and Mn in MW-B3
Fe MW-B3
Mn MW-B3
Linear (Fe MW-B3)
Linear (Mn MW-B3)
0.257
0.066 df SS MS F Significance F
-0.090 Regression 1.00 3406.05 3406.05 0.42 0.54
89.608 Residual 6.00 48177.82 8029.64
8 Total 7.00 51583.88
Coefficients Standard Error t Stat P-value Lower 95%Upper 95%Lower 95.0%Upper 95.0%
Intercept 114.84 56.59 2.03 0.09 -23.62 253.30 -23.62 253.30
X Variable 1 0.14 0.21 0.65 0.54 -0.38 0.65 -0.38 0.65
Adjusted R Square
Standard Error
Observations
Regression Statistics
ANOVAMultiple R
R Square

14
Figure 9 and Table 10 show that there is a statistically significant increase in Fe in MW-B9
because the F -statistic value of 2.85 shown in Table 10 is greater than the Significance F value
of 0.23.

Figure 9.-- Time trend in Fe and Mn in compliance well MW-B9.

Table 10.-- Regression analysis for the significance of the slope of the regression line for Fe in MW-B9.

Figure 10 and Table 11 show that there is a statistically significant increase in Fe in new
background well PMW-3 because the F -statistic value of 3.31 shown in Table 11 is less than
the Significance F value of 0.13.

0.767
0.588 df SS MS F Significance F
0.381 Regression 1.00 2778.98 2778.98 2.85 0.23
31.233 Residual 2.00 1951.02 975.51
4 Total 3.00 4730.00
Coefficients Standard Error t Stat P-value Lower 95%Upper 95%Lower 95.0%Upper 95.0%
Intercept 81.32 26.76 3.04 0.09 -33.82 196.46 -33.82 196.46
Days 0.19 0.12 1.69 0.23 -0.30 0.69 -0.30 0.69
Multiple R
R Square
Adjusted R Square
Standard Error
Observations
ANOVA
Fe in Compliance Well MW-B9
Regression Statistics
0
20
40
60
80
100
120
140
160
180
0 50 100 150 200 250 300 350 400
[F
e
]

&

[
M
n
]
,

u
g
/
l
Days since 11/01/2019
Fe and Mn in MW-B9
Fe MW-B9
Mn MW-B9
Linear (Fe MW-B9)
Linear (Mn MW-B9)

15

Figure 10.-- Time trend in Fe and Mn in new background well PMW-3.
.
Table 11.-- Regression analysis for the significance of the slope of the regression line for Fe in PMW-3.

Figure 11 and Table 12 show that there is a statistically significant decrease in Fe in new
background well PMW-4 because the F -statistic value of 3.14 shown in Table 12 is greater than
the Significance F value of 0.13. Although samples from PMW-4 showed values of Mn greater
than the detection limit, there is no significant time trend in these values because the F -statistic
value of 0.27 shown in Table 13 is less than the Significance F value of 0.62.

0.6312
0.3985 df SS MS F Significance F
0.2782 Regression 1 116812.66 116812.66 3.31 0.13
187.80 Residual 5 176343.05 35268.61
7 Total 6 293155.71
Coefficients Standard Error t Stat P-value Lower 95%Upper 95%Lower 95.0%Upper 95.0%
Intercept 54.42 120.03 0.45 0.67 -254.12 362.96 -254.12 362.96
X Variable 1 0.80 0.44 1.82 0.13 -0.33 1.94 -0.33 1.94
Regression Statistics
ANOVAMultiple R
R Square
Observations
Adjusted R Square
Standard Error

16

Figure 11.-- Time trend in Fe and Mn in new background well PMW-4.

Table 12.-- Regression analysis for the significance of the slope of the regression line for Fe in PMW-4.

Table 13.-- Regression analysis for the significance of the slope of the regression line for Mn in PMW-4.

0
20
40
60
80
100
120
140
160
180
200
0 100 200 300 400 500
[F
e
]

&

[
M
n
]
,

u
g
/
l
Days since 11/01/2019
Fe and Mn in PMW-4
Fe PMW-4
Mn PMW-4
Linear (Fe PMW-4)
Linear (Mn PMW-4)
0.6213
0.3860 df SS MS F Significance F
0.2632 Regression 1 4216.53 4216.53 3.14 0.14
36.6256 Residual 5 6707.19 1341.44
7 Total 6 10923.71
Coefficients Standard Error t Stat P-value Lower 95%Upper 95%Lower 95.0%Upper 95.0%
Intercept 109.90 23.41 4.69 0.01 49.72 170.07 49.72 170.07
X Variable 1 -0.15 0.09 -1.77 0.14 -0.37 0.07 -0.37 0.07
R Square
Regression Statistics
ANOVAMultiple R
Adjusted R Square
Standard Error
Observations
0.2278
0.0519 df SS MS F Significance F
-0.1377 Regression 1 262.65 262.65 0.27 0.62
30.9735 Residual 5 4796.78 959.36
7 Total 6 5059.43
Coefficients Standard Error t Stat P-value Lower 95%Upper 95%Lower 95.0%Upper 95.0%
Intercept 101.07 19.80 5.11 0.00 50.18 151.95 50.18 151.95
X Variable 1 -0.04 0.07 -0.52 0.62 -0.23 0.15 -0.23 0.15
Standard Error
Observations
Regression Statistics
ANOVAMultiple R
R Square
Adjusted R Square

17

Conclusions

The data from the 2010 study for Fe and Mn in groundwater samples is not statistically from the
same population as that from the data from the compliance and new background wells and
should not be used in assessing site-specific background standards.

The data from the background sampling program to date show that the mean and standard
deviation of the concentrations for Fe are lower than the 2L groundwater standard of 300 µg/l
respectively. Consequently, the 2L standards should continue to be used as the values for
compliance monitoring for Fe.

Because there appears to be statistically significant changes over time since the start of the
compliance sampling in November of 2019 in Fe concentrations in some of the compliance and
background wells, it is recommended that these trends be assessed on an annual basis to
determine if there is a basis for increasing the Fe standard for the site to a value greater than the
2L standard.

Concentrations of As in the compliance and background wells have all been less than the 2L
standard of 10 µg/l and therefore, that value should continue to be used as the value for
compliance monitoring.

This update, which includes samples taken on 3/10/2021, shows that the average Mn
concentration 66 µg/l is greater than the 2L standard of 50 µg/l. Therefore, it is recommended
that the site-specific background concentration for Mn be set at 66 µg/l.

The large number of non-detect concentrations of Mn in the compliance wells is likely the result
of dilution by historical irrigation applied to their up-gradient fields. The non-detect values of Mn
in PMW-2 and PMW-3 which are located cross-gradient from all sprayfields is likely the result of
dilution from surface runoff to and surface flow in the stream located between them and the
sprayfields.

18
Attachment 1 Approved Background Sampling Program

The following steps are recommended to implement the determination of background
concentrations of Fe and Mn at the Wrenn Road Site:

1. Install and develop the five (5) new background monitoring wells as recommended
herein;

2. Sample the background and compliance wells bi-monthly for six (6) months following
the installation and development of the new wells. The sampling should follow the
recommended low-flow purging, and field analysis for pH, Conductivity, Turbidity, and
Temperature. Samples taken should be analyzed in the CORPUD laboratory for As, Fe
and Mn This will provide a background sample size of 15 (5 wells x 3 samples) for each
constituent. One duplicate should be taken from a randomly selected background well
each sampling round;

3. Prepare probability plots of the 15 sample results for each constituent using the log
transform of the raw values; and visually compare to the plots for the 2010 samples;

4. Conduct One-way Analysis of Variance (ANOVA) on the log-transformed values to
assess whether the new background results are from the same population as the 2010
samples;

5. If the ANOVA shows that the new and 2010 samples are from the same population, pool
both to define the background statistics to use in compliance monitoring; or

6. If the ANOVA shows that the new and 2010 samples are not from the same population,
use only the new samples to define the background statistics to use in compliance
monitoring; and

Sample the new background wells for one year on the same schedule used for the compliance
wells (March, July, and November) to evaluate any time trends in As, Fe, Mn to consider in
compliance assessments. Log transformation should be applied to all these data.

19
Attachment 2 Sampling Reports from CORPUD
City of Raleigh
Wrenn Road Groundwater Monitoring Plan
Permit No. WQ0002708
Notes:
Before collecting samples, low flow well purging should continue until turbidity < 10 NTU or vary no more than 10%
Before collecting samples, pH and water temperature should be stable
One duplicate should be collected from one of the background wells for each sampling round
Try to use the same equipment during sampling, and note when alternate equipment is used to help account for a difference in results
Month November 2019 Background
Statistics MW-B3 PMW-1 PMW-2 PMW-3 PMW-4
D. Godfrey R. Tart D. Godfrey R. Tart D. Godfrey
11/5/19 11/21/19 11/21/19 11/21/19 11/21/19
8:05 11:18 8:40 12:23 12:10
Depth to water 21.65'24'8'6'21.9'
Total well depth 30'43'20'16'74'
Volume of water purged before
sampling (gal)4.25 gal 9.31 gal 6 gal 4.57 gal 25.5 gal
Turbidity (NTU)0.87 0.48 1.86 1.58 5.08
pH, units 5.23 5.75 5.3 6.03 5.97
Temperature, oC 16.6 16.6 16.8 16.9 17.6
Conductivity (umhos/cm)45.9 98.9 69.6 129.8 126.2
Iron (µg/L)180 <60 <60 199 172
Manganese (µg/L)<50 90 <50 <50 134
Arsenic (µg/L)<10 <10 <10 <10 <10
Clear/Cool/Sunny
Lab Data
Field Data
Sampled By
Date
Time
Daily Weather Condition
Location: MW-3
Collection Date Parameter Results Units of Measure Daily Max
Limits
05-Nov-19 Arsenic <10 ug/L 10
05-Nov-19 Conductivity 45.9 umhos/cm
05-Nov-19 Iron 180 ug/L 300
05-Nov-19 Manganese <50 ug/L 50
05-Nov-19 pH 5.23 su 6.5 - 8.5
05-Nov-19 Temperature 16.6 C
05-Nov-19 Turbidity 0.87 NTU
05-Nov-19 Arsenic <10 ug/L 10
05-Nov-19 Chloride <10 mg/L 250
05-Nov-19 Conductivity 45.9 umhos/cm
05-Nov-19 DO 2.39 mg/L
05-Nov-19 Fecal MPN 0 MPN/100 ml
05-Nov-19 Nitrate 0.8 mg/L 10
05-Nov-19 pH 5.23 su 6.5 - 8.5
05-Nov-19 Sulfate <10 ppm 250
05-Nov-19 Total Dissolved Solids @ 180 degrees
C 86 mg/L 500
05-Nov-19 Temperature 16.6 C
05-Nov-19 TOC <1.0 mg/L
Location: MW-8
Collection Date Parameter Results Units of Measure Daily Max
Limits
05-Nov-19 Arsenic <10 ug/L 10
05-Nov-19 Chloride 23.07 mg/L 250
05-Nov-19 Conductivity 94.9 umhos/cm
05-Nov-19 DO 2.86 mg/L
05-Nov-19 Fecal MPN 0 MPN/100 ml
05-Nov-19 Iron 76 ug/L 300
05-Nov-19 Manganese <50 ug/L 50
05-Nov-19 Nitrate 0.37 mg/L 10
05-Nov-19 pH 5.07 su 6.5 - 8.5
05-Nov-19 Sulfate <10 ppm 250
05-Nov-19 Total Dissolved Solids @ 180 degrees
C 142 mg/L 500
05-Nov-19 Temperature 15.5 C
05-Nov-19 TOC <1.0 mg/L
05-Nov-19 Turbidity 0.77 NTU
Location: MW-9
Collection Date Parameter Results Units of Measure Daily Max
Limits
05-Nov-19 Arsenic <10 ug/L 10
05-Nov-19 Chloride 27.66 mg/L 250
05-Nov-19 Conductivity 144.6 umhos/cm
05-Nov-19 DO 1.71 mg/L
05-Nov-19 Fecal MPN 0 MPN/100 ml
05-Nov-19 Iron 82 ug/L 300
05-Nov-19 Manganese <50 ug/L 50
05-Nov-19 Nitrate 1.29 mg/L 10
05-Nov-19 pH 5.05 su 6.5 - 8.5
05-Nov-19 Sulfate 10.36 ppm 250
05-Nov-19 Total Dissolved Solids @ 180 degrees
C 172 mg/L 500
05-Nov-19 Temperature 17.4 C
05-Nov-19 TOC <1.0 mg/L
05-Nov-19 Turbidity 1.52 NTU
Year: 2019
CITY OF RALEIGH
EM JOHNSON WATER PLANT LABORATORY
Wrenn Road Spray Irrigation Facility
Permit No. WQ0002708
Wells Monitoring Data Results
Month: November
City of Raleigh
Wrenn Road Groundwater Monitoring Plan
Permit No. WQ0002708
Notes:
Before collecting samples, low flow well purging should continue until turbidity < 10 NTU or vary no more than 10%
Before collecting samples, pH and water temperature should be stable
One duplicate should be collected from one of the background wells for each sampling round
Try to use the same equipment during sampling, and note when alternate equipment is used to help account for a difference in results
Month January 2020 Background
Statistics MW-B3 PMW-1 PMW-2 PMW-3 PMW-4
D. Godfrey R. Tart R. Tart R. Tart D. Godfrey
1/17/20 1/17/20 1/17/20 1/17/20 1/17/20
1002 1005 1049 818 1040
Depth to water 19.1 23.8 7.4 5.6 20.5
Total well depth 30'43'20'16'74'
Volume of water purged before
sampling (gal)4.75 gals 9.4 gals 6.1 gals 6.5 gals 27 gals
Turbidity (NTU)1.3 0.98 0.48 1.06 2.04
pH, units 4.86 5.87 6.02 6.68 6.07
Temperature, oC 16.2 14 15.1 12.8 15.3
Conductivity (umhos/cm)43 91.6 67.2 110.1 121.2
Iron (µg/L)98 <60 <60 <60 68
Manganese (µg/L)<50 74 <50 <50 <50
Arsenic (µg/L)<10 <10 <10 <10 <10
Field Data
Lab Data
Partly Sunny, Cool
Sampled By
Date
Time
Daily Weather Condition
City of Raleigh
Wrenn Road Groundwater Monitoring Plan
Permit No. WQ0002708
Notes:
Before collecting samples, low flow well purging should continue until turbidity < 10 NTU or vary no more than 10%
Before collecting samples, pH and water temperature should be stable
One duplicate should be collected from one of the background wells for each sampling round
Try to use the same equipment during sampling, and note when alternate equipment is used to help account for a difference in results
Month March 2020 Background
Statistics MW-B3 PMW-1 PMW-2 PMW-3 PMW-4
D. Godfrey D. Godfrey R. Tart R. Tart D. Godfrey
3/12/20 3/12/20 3/12/20 3/12/20 3/12/20
1040 1206 750 1230 959
Depth to water 19.1 20.85 7.5 5.3 16.2
Total well depth 30'43'20'16'74'
Volume of water purged before
sampling (gal)5.5 gals 11 gals 7 gals 5.25 gals 28.5 gals
Turbidity (NTU)0.78 1.31 0.53 3.49 1.76
pH, units 4.85 5.31 5.93 7.03 6.16
Temperature, oC 16.6 18.2 14.6 14.3 16.8
Conductivity (umhos/cm)41.4 90.9 71.8 62.2 115.4
Iron (µg/L)<60 <60 <60 141 <60
Manganese (µg/L)<50 64 <50 <50 88
Arsenic (µg/L)<10 <10 <10 <10 <10
Field Data
Lab Data
Cloudy, Cool
Sampled By
Date
Time
Daily Weather Condition
Location: MW-3
Collection Date Parameter Results Units of Measure Daily Max
12-Mar-20 Arsenic <10 ug/L 10
12-Mar-20 Chloride <10 mg/L 250
12-Mar-20 Conductivity 41.4 umhos/cm
12-Mar-20 DO 3.11 mg/L
12-Mar-20 Fecal MPN 0 MPN/100 ml
12-Mar-20 Iron <60 ug/L 300
12-Mar-20 Manganese <50 ug/L 50
12-Mar-20 Nitrate 0.68 mg/L 10
12-Mar-20 pH 4.85 pH 6.5 - 8.5
12-Mar-20 Sulfate <10 ppm 250
12-Mar-20 Total Dissolved Solids @ 180 degrees C 39 mg/L 500
12-Mar-20 Temperature 16.6 C
12-Mar-20 TOC <0.5 mg/L
12-Mar-20 Turbidity 0.78 NTU
Location: MW-8
Collection Date Parameter Results Units of Measure Daily Max
12-Mar-20 Arsenic <10 ug/L 10
12-Mar-20 Chloride 17.8 mg/L 250
12-Mar-20 Conductivity 77 umhos/cm
12-Mar-20 DO 5.20 mg/L
12-Mar-20 Fecal MPN 0 MPN/100 ml
12-Mar-20 Iron <60 ug/L 300
12-Mar-20 Manganese <50 ug/L 50
12-Mar-20 Nitrate 0.44 mg/L 10
12-Mar-20 pH 6.33 pH 6.5 - 8.5
12-Mar-20 Sulfate <10 ppm 250
12-Mar-20 Total Dissolved Solids @ 180 degrees C 62 mg/L 500
12-Mar-20 Temperature 15.5 C
12-Mar-20 TOC <0.5 mg/L
12-Mar-20 Turbidity 0.56 NTU
Location: MW-9
Collection Date Parameter Results Units of Measure Daily Max
12-Mar-20 Arsenic <10 ug/L 10
12-Mar-20 Chloride 11.41 mg/L 250
12-Mar-20 Conductivity 76.9 umhos/cm
12-Mar-20 DO 3.14 mg/L
12-Mar-20 Fecal MPN 0 MPN/100 ml
12-Mar-20 Iron 89 ug/L 300
12-Mar-20 Manganese <50 ug/L 50
12-Mar-20 Nitrate 0.54 mg/L 10
12-Mar-20 pH 7.02 pH 6.5 - 8.5
12-Mar-20 Sulfate <10 ppm 250
12-Mar-20 Total Dissolved Solids @ 180 degrees C 54 mg/L 500
12-Mar-20 Temperature 16.0 C
12-Mar-20 TOC 0.7404 mg/L
12-Mar-20 Turbidity 3.87 NTU
Month: March
Year: 2020
CITY OF RALEIGH
EM JOHNSON WATER PLANT LABORATORY
Wrenn Road Spray Irrigation Facility
Permit No. WQ0002708
Wells Monitoring Data Results
City of Raleigh
Wrenn Road Groundwater Monitoring Plan
Permit No. WQ0002708
Notes:
Before collecting samples, low flow well purging should continue until turbidity < 10 NTU or vary no more than 10%
Before collecting samples, pH and water temperature should be stable
One duplicate should be collected from one of the background wells for each sampling round
Try to use the same equipment during sampling, and note when alternate equipment is used to help account for a difference in results
Month April 2020 Compliance
Monitoring MW-B3 PMW-1 PMW-2 PMW-3 PMW-4
D. Godfrey R. Tart R. Tart R. Tart D. Godfrey
4/14/20 4/14/20 4/14/20 4/14/20 4/14/20
1107 1015 830 1145 1028
Depth to water 19'20.9'7.7'5.7'16.4'
Total well depth 30'43'20'16'74'
Volume of water purged before
sampling (gal)5.5 Gallons 10.8 Gallons 6.5 Gallons 5.0 Gallons 28.25 Gallons
Turbidity (NTU)0.44 0.39 0.23 0.46 1.61
pH 4.82 7.15 7.32 6.27 6.05
Temperature 17.2 17.6 14.8 15.5 17
Conductivity (umhos/cm)39.8 92.2 68.8 116.4 110.8
Iron (µg/L)65 <60 <60 <60 <60
Manganese (µg/L)<50 70 <50 <50 96
Arsenic (µg/L)<10 <10 <10 <10 <10
Sunny, Clear 60s
Field Data
Lab Data
Sampled By
Date
Time
Daily Weather Condition
Location: MW-3
Collection Date Parameter Units of Measure Results
7/8/2020 pH su 5.19
7/8/2020 Fecal Coliform col/100 ml 0
7/8/2020 Total Dissolved Solids @ 180°C mg/l 38
7/8/2020 Total Organic Carbon mg/l <0.5
7/8/2020 Chloride mg/l 5.17
7/8/2020 Nitrate Nitrogen mg/l 0.44
7/8/2020 Sulfate mg/l <5
7/8/2020 Iron ug/l 234
7/8/2020 Manganese ug/l <50
7/8/2020 Arsenic ug/l <10
7/8/2020 Total Phosphorus mg/l <0.05
7/8/2020 Acrylamide ug/l <0.50
Location: MW-8
Collection Date Parameter Units of Measure Results
7/8/2020 pH su 5.35
7/8/2020 Fecal Coliform col/100 ml 0
7/8/2020 Total Dissolved Solids @ 180°C mg/l 55
7/8/2020 Total Organic Carbon mg/l <0.5
7/8/2020 Chloride mg/l 17.9
7/8/2020 Nitrate Nitrogen mg/l 0.02
7/8/2020 Sulfate mg/l <5
7/8/2020 Iron ug/l <60
7/8/2020 Manganese ug/l <50
7/8/2020 Arsenic ug/l <10
7/8/2020 Total Phosphorus mg/l <0.05
7/8/2020 Acrylamide ug/l <0.50
Location: MW-9
Collection Date Parameter Units of Measure Results
7/8/2020 pH su 5.32
7/8/2020 Fecal Coliform col/100 ml 0
7/8/2020 Total Dissolved Solids @ 180°C mg/l 71
7/8/2020 Total Organic Carbon mg/l 1.01
7/8/2020 Chloride mg/l 20.9
7/8/2020 Nitrate Nitrogen mg/l 1.47
7/8/2020 Sulfate mg/l 6.99
7/8/2020 Iron ug/l 166
7/8/2020 Manganese ug/l <50
7/8/2020 Arsenic ug/l <10
7/8/2020 Total Phosphorus mg/l <0.05
7/8/2020 Acrylamide ug/l <0.50
500
CITY OF RALEIGH
EM JOHNSON WATER PLANT LABORATORY
Wrenn Road Spray Irrigation Facility
Permit No. WQ0002708
Wells Monitoring Data Results
Month: July
Year: 2020
Daily Max
6.5 - 8.5
6.5 - 8.5
250
10
250
300
50
10
0.008
Daily Max
500
250
10
250
300
50
10
0.008
Daily Max
6.5 - 8.5
500
50
0.008
250
10
250
300
10
City of Raleigh
Wrenn Road Groundwater Monitoring Plan
Permit No. WQ0002708
Notes:
Before collecting samples, low flow well purging should continue until turbidity < 10 NTU or vary no more than 10%
Before collecting samples, pH and water temperature should be stable
One duplicate should be collected from one of the background wells for each sampling round
Try to use the same equipment during sampling, and note when alternate equipment is used to help account for a difference in results
Month August 2020 Compliance
Monitoring MW-B3 PMW-1 PMW-1 Dup PMW-2 PMW-3 PMW-4
Roy Tart Roy Tart Roy Tart Roy Tart Roy Tart Roy Tart
8/20/20 8/20/20 8/20/20 8/20/20 8/20/20 8/20/20
14:35 13:25 13:25 12:01 15:15 12:45
Depth to water 20.3 22.8 22.8 9.8 6 19
Total well depth 30 43 43 20 30 74
Volume of water purged before
sampling (gal)4.7 9.8 9.8 5.1 5 26
Turbidity (NTU)0.9 0.68 0.68 1.46 1.69 1.5
pH 5.8 5.93 5.93 6.01 6.63 6.81
Temperature 18.5 19.1 19.1 20.7 19.8 19
Conductivity (umhos/cm)111 94.5 96.7 73.3 43.5 124.5
Iron (µg/L)118 <60 <60 <60 482 69
Manganese (µg/L)<50 88 90 <50 <50 123
Arsenic (µg/L)<10 <10 <10 <10 <10 <10
Cloudy 80oF
Field Data
Sampled By
Date
Time
Daily Weather Condition
City of Raleigh
Wrenn Road Groundwater Monitoring Plan
Permit No. WQ0002708
Notes:
Before collecting samples, low flow well purging should continue until turbidity < 10 NTU or vary no more than 10%
Before collecting samples, pH and water temperature should be stable
One duplicate should be collected from one of the background wells for each sampling round
Try to use the same equipment during sampling, and note when alternate equipment is used to help account for a difference in results
Month November 2020 Compliance
Monitoring MW-B3 PMW-1 PMW-1 Dup PMW-2 PMW-3 PMW-4
D. Godfrey D. Godfrey D. Godfrey D. Godfrey D. Godfrey D. Godfrey/E.
Batchelor
11/4/20 11/4/20 11/4/20 11/4/20 11/4/20 11/4/20
9:43 8:25 8:25 9:08 10:44 12:00
Clear 48 oC Clear 40 oC Clear 40 oC Clear 40 oC Clear 55 oC Clear 62 oC
Depth to water 19.95 22.3 22.3 7.8 5.7 18.9
Total well depth 30'43'43'20'16'74'
Volume of water purged before
sampling (gal)5 10.25 10.25 6 5.25 27
Turbidity (NTU)0.73 1.12 1.12 1.86 0.44 0.72
pH 4.79 5.32 5.32 5.08 5.65 5.87
Temperature 17.8 17 17 18.5 18.1 18.2
Conductivity (umhos/cm)41.4 82 82.4 73.6 101.5 129.8
Iron (µg/L)301 <60 <60 72 73 <60
Manganese (µg/L)<50 59 61 <50 <50 88
Arsenic (µg/L)<10 <10 <10 <10 <10 <10
Sampled By
Date
Time
Daily Weather Condition
Field Data
Location: MW-3
Collection Date Parameter Results Units of Measure Daily Max
04-Nov-20 Arsenic <10 ug/L 10
04-Nov-20 Conductivity 41.4 umhos/cm
04-Nov-20 Iron 334 ug/L 300
04-Nov-20 Manganese <50 ug/L 50
04-Nov-20 pH 4.79 su 6.5 - 8.5
04-Nov-20 Temperature 17.8 C
04-Nov-20 Turbidity 0.73 NTU
05-Nov-20 Arsenic <10 ug/L 10
05-Nov-20 Chloride 6.073 mg/L 250
05-Nov-20 Conductivity 40.3 umhos/cm
05-Nov-20 DO 2.06 mg/L
05-Nov-20 Fecal MPN 0 MPN/100 ml
05-Nov-20 Iron 301 ug/L 300
05-Nov-20 Manganese <50 ug/L 50
05-Nov-20 Nitrate 0.35 mg/L 10
05-Nov-20 pH 4.52 su 6.5 - 8.5
05-Nov-20 Sulfate <5 ppm 250
05-Nov-20 Total Dissolved Solids @ 180 degrees 41 mg/L 500
05-Nov-20 Temperature 17.2 C
05-Nov-20 TOC <1.0 mg/L
05-Nov-20 Total Phosphorus <0.04 mg/L
05-Nov-20 Turbidity 0.76 NTU
Location: MW-8Collection Date Parameter Results Units of Measure Daily Max
05-Nov-20 Arsenic <10 ug/L 10
05-Nov-20 Chloride 21.932 mg/L 250
05-Nov-20 Conductivity 91.4 umhos/cm
05-Nov-20 DO 3.78 mg/L
05-Nov-20 Fecal MPN 0 MPN/100 ml
05-Nov-20 Iron <60 ug/L 300
05-Nov-20 Manganese <50 ug/L 50
05-Nov-20 Nitrate <0.04 mg/L 10
05-Nov-20 pH 4.69 su 6.5 - 8.5
05-Nov-20 Sulfate <5 ppm 250
05-Nov-20 Total Dissolved Solids @ 180 degrees 73 mg/L 500
05-Nov-20 Temperature 16.2 C
05-Nov-20 TOC <1.0 mg/L
05-Nov-20 Total Phosphorus <0.04 mg/L
05-Nov-20 Turbidity 0.88 NTU
Location: MW-9Collection Date Parameter Results Units of Measure Daily Max
05-Nov-20 Arsenic <10 ug/L 10
05-Nov-20 Chloride 22.576 mg/L 250
05-Nov-20 Conductivity 122.0 umhos/cm
05-Nov-20 DO 1.41 mg/L
05-Nov-20 Fecal MPN 0 MPN/100 ml
05-Nov-20 Iron 135 ug/L 300
05-Nov-20 Manganese <50 ug/L 50
05-Nov-20 Nitrate 1.04 mg/L 10
05-Nov-20 pH 4.64 su 6.5 - 8.5
05-Nov-20 Sulfate 8.892 ppm 250
05-Nov-20 Total Dissolved Solids @ 180 degrees 81 mg/L 500
05-Nov-20 Temperature 17.3 C
05-Nov-20 TOC <1.0 mg/L
05-Nov-20 Total Phosphorus <0.04 mg/L
05-Nov-20 Turbidity 5.97 NTU
Year: 2020
CITY OF RALEIGH
EM JOHNSON WATER PLANT LABORATORY
Wrenn Road Spray Irrigation Facility
Permit No. WQ0002708
Wells Monitoring Data Results
Month: November
City of Raleigh
Wrenn Road Groundwater Monitoring Plan
Permit No. WQ0002708
Notes:
Before collecting samples, low flow well purging should continue until turbidity < 10 NTU or vary no more than 10%
Before collecting samples, pH and water temperature should be stable
One duplicate should be collected from one of the background wells for each sampling round
Try to use the same equipment during sampling, and note when alternate equipment is used to help account for a difference in results
Month March 2021 Compliance
Monitoring MW-B3 PMW-1 PMW-1 Dup PMW-2 PMW-3 PMW-4
D. Godfrey D. Godfrey D. Godfrey D. Godfrey D. Godfrey D. Godfrey
3/10/21 3/10/21 3/10/21 3/10/21 3/10/21 3/10/21
7:50 8:50 8:50 9:22 11:16 13:00
Sunny 39 oC Sunny 43oC Sunny 43 oC Sunny 50 oC Sunny 65 oC Sunny 67oC
Depth to water 16.8'18.3 18.3 6.9 5.9 14.1
Total well depth 30'43'43'20'16'74'
Volume of water purged before
sampling (gal)6.5 12.25 12.25 6.5 5 30
Turbidity (NTU)0.72 3.52 3.52 1.52 2.83 0.72
pH 5.3 5.62 5.62 5.75 6.48 5.85
Temperature 15.8 16.5 16.5 15.5 14.2 19.8
Conductivity (umhos/cm)38.35 84.53 83.03 79.36 85.17 123.9
Iron (µg/L)108 97 132 199 601 <50
Manganese (µg/L)<10 71 71 16 176 71
Arsenic (µg/L)<5 <5 <5 <5 <5 <5
* Trace Metal Analysis by Environment 1
Sampled By
Date
Time
Daily Weather Condition
Field Data

Ground Water
Monitoring Plan
Wrenn Road Facility Wastewater Irrigation
System

Garner, NC
February 26, 2019

hdrinc.com
555 Fayetteville Street Suites 900 & 210, Raleigh, NC 27601-3034
[phone]

February 26, 2019

Mr. Rick Bolich
NC Department of Environmental Quality
Division of Water Resources
Water Quality Regional Operations Section
Raleigh Regional Office
3800 Barrett Drive
Raleigh, NC 27609

Re: Ground Water Monitoring Plan
Permit No. WQ0002708
City of Raleigh Wrenn Road Facility Wastewater Irrigation System
Wake County, North Carolina
Dear Mr. Bolich,
On behalf of the City of Raleigh Public Utilities Department, we are resubmitting the Ground Water
Monitoring Plan requested in the approval for Permit Number WQ0002708 to support background
concentrations of manganese, iron and arsenic above the 15A NCAC 02L standards. The sampling
plan has been prepared with consideration to the guidance material suggested in the Permit
Approval letter: Aquifer Protection Section Policy for metals Determinations Required by Title 15A,
NCAC, Subchapter 2L (May, 2013) and Evaluating Metal in Groundwater at DWQ Permitted
Facilities: A Technical Assistance Document for DWQ Staff (NC DENR, July, 2012). Also, the
following US EPA groundwater monitoring guidance document was utilized: Statistical Analysis of
Groundwater Monitoring Data at RCRA Facilities-Unified Guidance: EPA 530/R-09-007.
Additionally, recommendations offered by DEQ during discussions with the City and HDR were
incorporated into the sampling plan.
In summary, the revised sampling plan will:
1. Install and develop four (4) background monitoring wells at the Wrenn Road Facility;
2. These wells will be sampled for iron, manganese, and arsenic bi-monthly for the first six (6)
months to develop background statistics for compliance monitoring;
3. Determine if 2010 sampling data is from the same population and for use in defining
background statistics for ground water monitoring;
4. Sample the new background wells for one (1) year on the same schedule used for
compliance monitoring to evaluate any time trends to consider in compliance assessments;
5. The new ground water monitoring wells will be m aintained such that resampling can be
accomplished in the future if necessary.
hdrinc.com
555 Fayetteville Street Suites 900 & 210, Raleigh, NC 27601-3034
[phone]

This package contains the following:
Attachment A – The ground water monitoring plan submitted to DEQ on February 28, 2017
Attachment B – Responses to comments provided to DEQ on October 7, 2017
Attachment C – The resubmittal to DEQ by the City/HDR on December 14, 2018, providing
revised background monitoring well locations
Attachment D – Meeting minutes from a meeting held with the City, HDR, Eagle Resources,
and DEQ on January 31, 2019
Attachment E – W ater well locations for the subdivision located adjacent to the Wrenn
Road Facility
Attachment F – Ground water well levels
Attachment G – A contour map of the proposed monitoring well locations
The groundwater permit WQ0002708 expires June 30, 2020. The I-540 project will impact the
Wrenn Road Facility and the compliance boundary. The exact timing of the I-540 project is
unknown at this time. The City will keep DEQ informed as to the progress of this project.
We have submitted a full package in order to hopefully help the review process. Should you have
any questions, please do not hesitate to call me at 919-232-6657. We look forward to hearing from
the NC Department of Environmental Quality.
Sincerely,
HDR Engineering Inc. of the Carolinas

Chris Brown, PE
Project Manager

Enclosures
cc: Chris Phelps, City of Raleigh
Dennis Lassiter, City of Raleigh
Whit Wheeler, City of Raleigh
Eric Lappala, Eagle Resources
Samantha Black, HDR
Manish Bhandari, HDR

A
Ground Water Monitoring
Plan – Submitted February
28, 2017

01
hdrinc.com
February 28, 2017
Mr. Troy Dotty
Non -Discharge Permitting Unit
Water Quality Permitting Section
Division of Water Resources
512 N. Salisbury Street
Raleigh, NC 27604
Re: Ground Water Monitoring Plan
Permit No. WQ0002708
City of Raleigh Wrenn Road Facility Wastewater Irrigation System
Wake County, North Carolina
Dear Mr. Dotty,
On behalf of the City of Raleigh Public Utilities Department, we are providing the Ground Water
Monitoring Plan requested in the approval for Permit Number WQ0002708 to support background
concentrations of Manganese, Iron and Arsenic above the 15A NCAC 02L standards. The
sampling plan has been prepared with consideration to the guidance material suggested in the
Permit Approval letter: Aquifer Protection Section Policy for metals Determinations Required by
Title 15A, NCAC, Subchapter 2L (May, 2013) and Evaluating Metal in Groundwater at DWQ
Permitted Facilities: A Technical Assistance Document for DWQ Staff (NC DENR, July, 2012).
Also, the following US EPA groundwater monitoring guidance document was utilized: Statistical
Analysis of Groundwater Monitoring Data at RCRA Facilities -Unified Guidance: EPA 530/R-09-007.
Based on these sources and other groundwater modeling tools a ground water monitoring plan has
been developed. This detailed groundwater monitoring pian is attached, 'Proposed Monitoring Plan
to Establish Background Concentration of Iron and Manganese at the Wrenn Road Spray Fields,
Wake County NC" (Plan) by Eric Lappala, P.E., P.H., Eagle Resources.
In summary the sampling plan will:
1. Install and develop five (5) new monitoring wells at the Wrenn Road Facility;
2. These wells will be sampled for Iron, Manganese and Arsenic, bi-monthly for the first six (6)
months to develop the background statistics for compliance monitoring;
3. Determine if 2010 sampling data is from the same population and for use in defining
background statistics for ground water monitoring;
4. Sample the new background wells for one (1) year on the same schedule used for
compliance monitoring, to evaluate any time trends to consider in compliance assessments.
5. The new ground water monitoring wells shall be maintained such that resampling can be
accomplished if necessary.
3733 National Drive Suite 207, Raleigh NC 27612
T 919.232.6600 F 919.785.1187

Should you have any questions, please do not hesitate to call me at [phone].
Sincerely,
HDR Engineering Inc. of the Carolinas
�°---
Randy Plummer, PE
Project Manager
RTP
Enclosures
cc: Chris Phelps
Dennis Lassiter
3733 National Drive Suite 207, Raleigh NC 27612
T 919.232.6600 F 919.785.1187

1

Proposed Monitoring Plan to Establish Background
Concentration of Iron and Manganese at the
Wrenn Road Sprayfields, Wake County, NC

North Carolina Non-Discharge Permit WQ0002708

Prepared for
City of Raleigh Pubic Utilities Department and
HDR Engineering of the Carolinas

April 1, 2016
(Revised February 1, 2017)

Eric G. Lappala, P.E., P.H.

Eagle Resources, P.A.
P.O. Box 11189
Southport, NC
www.eagleresources.com

i

Contents
Introduction ................................................................................................................................................. 1
Purpose ........................................................................................................................................................ 1
Model Analyses to select sites for background monitoring ........................................................................ 2
Sampling Design ......................................................................................................................................... 8
1. Identical and Independent Distributions of background and forward samples ..................... 8
2. Temporal Stationarity of Samples ............................................................................................. 10
3. Spatial Stationarity of Samples ................................................................................................. 10
4. Statistical Outliers ....................................................................................................................... 12
5. Use of Parametric Methods ........................................................................................................ 12
6. Minimum Number of Background Samples ............................................................................ 12
a) Additional Background Wells ................................................................................................ 13
b) Sampling to Establish Background ....................................................................................... 14
c) Initial Sampling Methodology Assessment ........................................................................... 14
Recommended Background Determination Methodology ....................................................................... 15
Conclusions ............................................................................................................................................... 16

Figures
Figure 1.-- Measured and modeled water level elevations in B-3, B-8, and B-9 ....................................... 3
Figure 2.-- Modeled concentrations of the modeled constituent in model layer 1 as of 12/31/15. ............ 5
Figure 3.-- Modeled concentrations of the modeled constituent in model layer 2 as of 12/31/15. ............ 6
Figure 4.-- Modeled concentrations of the modeled constituent in model layer 3 as of 12/31/15. ............ 7
Figure 5.-- Probability Plots for (Fe / 2L standard) and (Mn / 2L standard) for the 2010 study samples..
............................................................................................................................................................. 9
Figure 6.-- Probability plots of log-transformed values of (Fe 2L Standard) and (Mn / 2L Standard) for
the 2010 study samples. .................................................................................................................... 10
Figure 7.-- Log-transformed multiple of Fe (left panel) and Mn (right panel) multiples of the 2L
Standards for samples from the 2010 study. ..................................................................................... 11
Figure 8.-- Dissolved Fe and Mn plotted against each other showing little correlation between them. ... 12

Tables
Table 1.—Dissolved Fe and Mn from the 2010 study, their multiples of the 2L standards and the log
transform of the multiples of the 2L standards. .................................................................................. 9
Table 2.-- Coordinates of Proposed Background Monitoring Wells. ....................................................... 13
Table 3.-- Results of purging of compliance wells on February 5, 2016 and laboratory analyses for
dissolved Fe and Mn in samples taken at the end of purging.. ......................................................... 15

1
Introduction
NC DEQ has granted Permit WQ0002708 to the City of Raleigh (City) for the continued operation and
irrigation at the Wrenn Road Facility in southeastern Wake County. This permit is a renewal for the
permit of the same number that was in effect originally to permit the same facilities for the disposal of
wastewater effluent from the treatment facilities. The Wrenn road Facility stopped receiving domestic
wastewater in 2008. The spray irrigation facilities were modified to allow treatment of residuals from
the DE Benton Water Treatment Plant (DEBWTP). WQ0002708 was amended in 2012 for the spray
irrigation modifications and to change the influent waste source to residuals from the DEBWTP. The
spray irrigation permit was renewed in 2015. The sprayfields have been used since 1989 to dispose of
treated wastewater from the Garner wastewater treatment plant (Garner WWTP). The Town of Garner
operated the WR Sprayfields until the merger of the Garner water and sewer utility systems with the
City of Raleigh in July 2000. The City of Raleigh Public Utilities Department (CORPUD) has operated
the Garner wastewater plant and the WR Sprayfields since that date.

A comprehensive Hydrogeologic and Geochemical evaluation of the site was completed by Soil and
Environmental Consultants (S&EC) and Eagle Resources for the site in 2010 and approved by DEQ as
part of the application for the currently issued permit1,2,. These studies comprised the installation of
over 20 temporary piezometers, three monitoring wells, and groundwater flow, groundwater transport,
and geochemical modeling to assess both conditions prior to the application of residuals from the WTP
and to recommend loading rates to the sprayfields to assure that the likely depth to the watertable would
be compliant with the conditions of the permit.

Purpose
The permit was issued by DEQ with the condition that the City prepare a monitoring plan to assess the
background concentrations of arsenic, iron and/or manganese above the 15A NCAC .02L groundwater
standards (2L Standards). The 2010 reports documented concentrations of these constituents in samples
collected from piezometers and monitoring wells that exceeded the 2L Standards. The permit condition
also requested that CORPUD consider DWQ Staff guidance documents3,4 in preparing the plan.

These guidance documents include the statistical evaluation of data used to establish background
concentrations to account for spatial variations across complex sites. Because the piezometers from the
2010 studies have been abandoned, they and are no longer available to use for re-development and
sampling to provide this data. The three monitoring wells that have been used for compliance reporting
since the original permit was issued for the site (MW-B3, MW-B8, and MW-B-9) also are not adequate
in number or location to use for the establishment of background concentrations. These wells are not
located in areas where the 2010 study showed concentrations of the regulated metals to be above the 2L
Standards. Additionally, only three rounds of samples have been taken that have included analyses for
the metals of concern since the permit was issued and application of residuals was started in 2014.

The objective of this report is to present a plan for using data and analyses from the 2010 study
documents combined with data from additional monitoring locations to respond to the permit condition
to assess the background concentrations of iron and manganese at the facility.

1 Soil and Environmental Consultants, 2009, Site Analysis for Wrenn Road Wastewater Treatment Plant Spray Irrigation
system, Garner., Wale County, North Carolina
2 Eagle Resources, P.A., May 10, 2010, Groundwater Mounding Analysis and Groundwater Quality Assessment Wrenn Road
Wastewater Treatment Plan Spray Irrigation System Garner, Wake County, North Carolina
3 NC Division of Water Quality, July 2012: Evaluating Metals in Groundwater at DWQ Permitted Facilities: a Technical
Assistance Document for DWQ Staff.
4 NC Division of Water Quality, May 13, 2013: Aquifer Protection Section Policy for Metals Determinations Required by Title
15A North Carolina Administrative Code, Subchapter 2L.

2

Based upon the DEQ guidance documents, determination of the quality and quantity of background data
needed should consider the following:
“
1. Physical complexity of the site
a. Does site geology vary horizontally across the site
b. Are off-site wastes likely to migrate to and contaminate background or compliance
boundary wells
c. Have Hydrogeologic anomalies been identified?
d. Have wastes been disposed across particularly large or undocumented areas
e. Spatial extent and complexity of the waste disposal practices
2. Are background concentrations expected to be similar to 2L standards and/or similar to on-site
concentrations at the compliance boundary
3. Will site be used as a precedent for similar sites in the state
4. Will statistical proof be required to justify a non-compliance determination

At a minimum, collected data should measure maximum concentrations of permitted waste constituents
that exist at the compliance boundary and at ambient background locations, along with any spatial or
temporal trends. Moreover, sample numbers and locations should align with statistical data needs....

Therefore, background data should be collected from a hydraulically up gradient location (outside the
influence of site wastes) in immediate proximity to the site and within the same groundwater horizon
(depth/zone) as samples collected from compliance boundary wells. ….”

Model Analyses to select sites for background monitoring
The 2010 studies and analyses provide the documentation of the items listed above that define the
physical complexity of the site. The calibrated groundwater flow and transport model constructed for
those studies was based on site-specific data from borings, piezometers (19) monitoring wells (3), water
levels, tests for hydraulic conductivity, chemical and geochemical analyses of water samples. The
model was constructed using three layers: The Saprolite at the site was modeled as two layers each 17.7
feet thick which are referred to as the Upper Saprolite and Lower Saprolite respectively. The third layer
comprised Partially Weathered Rock (PWR) and was 15 feet thick.

Transient analyses using the model have been used to help identify those areas that are not likely to
have been impacted by migration of constituents in water applied to the Wrenn Road fields during 2014
and 2015. The initial water levels used for the transient analyses with the model were the steady state
values from the calibrated 2010 model which used a natural recharge rate of using a recharge rate of 15
inches per year. Monthly recharge for 2014 and 2015 used for model input was determined as follows:

Recharge on non-sprayfield areas = Precipitation – Evapotranspiration (ET); and (1)

Recharge on spray areas = Precipitation + Applied Effluent – ET. (2)

Precipitation for each month was taken from the grid centered on the site out of the 4km x 4km gridded
values from the National Precipitation Dataset from the PRISM website5. The PRISM datasets are

5 http://www.prism.oregonstate.edu/

3
computed using measurements from a wide range of monitoring networks that cover the conterminous
United States to which sophisticated quality control measures and a variety of modeling techniques are
applied and are available as daily, monthly and yearly time scales for the period from 1895 to the
present.

ET was taken from the global monthly ET 0.05 degree grid corresponding to the site from the MODIS
project6. This project is part of NASA/EOS project to estimate global terrestrial evapotranspiration from
earth land surface by using satellite remote sensing data. The MOD16 ET datasets are estimated using
Mu et al.’s improved ET algorithm (2011) over previous Mu et al.’s paper (2007a). The ET algorithm is
based on the Penman-Monteith equation (Monteith, 1965). Surface resistance is an effective resistance
to evaporation from land surface and transpiration from the plant canopy.

Applied effluent to each field for each month was computed using the volume applied as reported on the
Discharge Monitoring Reports (DMRs) provided by CORPUD and tables provided by HDR of the
percentage of spray heads applying to each soil type within each field that are included as Attachment 1
to this report. Attachment 2 provides a summary tabulation of the monthly effluent applied to each soil
type within each field. The unit rate applied effluent in equation (2) was determined by dividing the
volume applied by the area occupied by each soil within each field.

Modeled water level elevations in B-3, B-8, and B-9 for the period 2014 through 2015 are shown on
Figure 1 along with measured water level elevations for 2007 through 2015 Although water levels
fluctuate, they tend to fluctuate in unison over the site and model analyses show that the pattern of
groundwater flow that are determined by recharge and discharge areas does not change significantly.
.

Figure 1.-- Measured and modeled water level elevations in B-3, B-8, and B-9

6 http://www.ntsg.umt.edu/project/mod16
150
180.25
210.5
240.75
271
301.25
331.5
361.75
6/1/06 5/22/07 5/11/08 5/1/09 4/22/10 4/12/11 4/1/12 3/22/13 3/13/14 3/3/15
Wa
t
e
r

L
e
v
e
l

E
l
e
v
a
t
t
i
o
n
,

N
A
V
D
8
8

F
e
e
t
B-3
B-8
B-9
B-3 Modeled Sy = 0.25
B-8 Modeled Sy = 0.25
B-9 Modeled Sy = .25

4
Transient transport analyses for 2014 through 2015 were conducted to assess potential migration of
COCs in effluent from DEB WTP and to locate areas where it is not likely to have impacted
groundwater and hence where background monitoring sites should be located. The source term used for
these analyses was an arbitrary constituent at a concentration of 10 arbitrary units applied to the areas
that received effluent during 2014 and 2015. Figures 2 through 4 show the modeled concentrations of
the arbitrary constituent as of December 31, 2015 for each of the modeled layers.
500
6
Eagle Resources, P.A.
P.O. Box 11189
Southport, NC 28461
919-345-1013
[e-mail]
10
j -
4
EXPLANATION
Layer 1
[C] Monitoring Wells
0
Compliance Well
�1
Monitoring Well
2
F—I 3
Proposed Background Well
F—I 4
0 2010 Mn X 2L Std (Purple)
5
0 2010 Fe X 2L Std (Orange)
Areas Irrigated in 2014 and 2015
CORPUD_Property_Boundary
$
Base: USGS 2010
9
10
0 500 1000 1500 2000 Ft
Project N0.
J
Design data and recommendations included herein are provided as a
matter of information and should not be used for final design. Rely only on
City of
24041.1
hard copy bearing consultants original seal and signature
Raleigh
Approved: EGL
Modeled concentrations in Upper Saprolite of an
Public
arbitrary solute on 12/31/2015 applied in irrigation
Utilties
water at concentration of 10 arbitrary units for 2014
Department
Date: 02/21 /16
and 2015.
FIGURE
2
4

.A
l
1500 2000 Ft
T
n
LIr"Ppow I
EXPLANATION
Layer 1 [C] Monitoring Wells
0 Compliance Well
�1
2 Monitoring Well
3 Proposed Background Well
F—I 4 0 2010 Mn X 2L Std (Purple)
L:::] 5 0 2010 Fe X 2L Std (Orange)
F—I 6 Areas Irrigated in 2014 and 2015
E:1 7 CORPUD_Property_Boundary
8 Base: USGS 2010
9
10
elees
Project No.
City of 24042.1
Raleigh Approved: EGL
Public
data and recommendations included herein are provided as a
matter
matter of information and should not be used for final design. Rely only on
hard copy bearing consultants original seal and signature
DRAFT
FIGURE
3
Modeled concentrations in Lower Saprolite of an
arbitrary solute on 12/31/2015 applied in irrigation
Eagle Resources, P.A.
P.O. Box 11189
Southport, NC 28461
Utilties
water at concentration of 10 arbitrary units for 2014
919-345-1013
Department Date: 02/21 /16
and 2015.
[e-mail]
5

O
�5
' AIL to x
500 0 500 1000 1500 2000 Ft
EXPLANATION
PWR [C]
Monitoring Wells
0
Compliance Well
1
Monitoring Well
0 2
3
Proposed Background Well
0 4
0 2010 Mn X 2L Std (Purple)
0 5
0 2010 Fe X 2L Std (Orange)
6%/
Areas Irrigated in 2014 and 2015
7
0 CORPUD_Property—Boundary
8
Base: USGS 2010
9
10
.q
City Of
Project No.
24041.1
data and recommendations included herein are provided as a
matter
matter of information and should not be used for final design. Rely only on
hard copy bearing consultants original seal and signature
FIGURE
b_
-4f 1 �5
Raleigh
Approved: EGL
Modeled concentrations in Lower Saprolite of an
Eagle Resources, P.A.
P.O. Box 11189
Public
arbitrary solute on 12/31/2015 applied in irrigation
DRAFT
4
Southport, NC 28461
Utilties
water at concentration of 10 arbitrary units for 2014
919-345-1013
Department
Date: 02/21 /16
and 2015.
[e-mail]
6

8
Sampling Design
DEQ has determined that the data from the 2010 report should not be used to establish background
values because the wells were not permanent and because their sampling may not have met the currently
recommended sampling methodology for metals. However, because the sample size is relatively large
(n = 21) from that study and to provide a guide to the approximate variability in concentrations of iron
and manganese over the site as an aid to establishing a background monitoring program to meet these
requirements, we have included that data its summary statistics in Table 1 as well as their as multiples
of the 2L standards. Their multiples of the 2L Standards are also shown on Figures 2 through 4 to
illustrate their spatial variability.

The USEPA guidance document7 on groundwater monitoring for compliance purposes which is
referenced in the DEQ guidance document provides the following six requirements for establishing
prediction limits for comparing background and future compliance samples:

1. Background and future sample measurements need to be identically and independently distributed;
2. Sample data do not exhibit temporal non-stationarity in the form of trends, autocorrelation, or other
seasonal or cyclic variation;
3. For inter-well tests (e.g., up-gradient-to-downgradient comparisons), sample data do not exhibit non-
stationary distributions in the form of significant natural spatial variability;
4. Background data do not include statistical outliers;
5. For parametric prediction limits, background data are normal or can be normalized using a
transformation; and
6. A minimum of 8 background measurements is available; more for non-parametric limits or when
accounting for multiple, simultaneous prediction limit tests.

1. Identical and Independent Distributions of background and forward samples
To assess the likely distributions of these data, probability plots for the multiples of the 2L standards are
shown in Figure 5. Examination of these plots and the value of the skew coefficients in Table 1 show
that the raw data is not normally distributed. However, the the log transform of the multiples of the 2L
standards closely approximate normal distributions as shown by the fit to the straight normal probability
line in Figure 6. Therefore, to meet the requirements 1 and 5 above, all background and forward
compliance samples should be log-transformed. Note that for both Mn and Fe a value of the log
transformed value of 0.0 for the multiple of the standard is equivalent to the 2L Standard (Value /
Standard = 1.0).

7 U.S. Environmental Protection Agency, March, 2009: Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities-
Unified Guidance: EPA 530/R-09-007, chapter 18, pp 18-4.

9

Figure 5.-- Probability Plots for (Fe / 2L standard) and (Mn / 2L standard) for the 2010 study samples..

Table 1.—Dissolved Fe and Mn from the 2010 study, their multiples of the 2L standards and the log transform of the multiples of the 2L
standards.

R² = 0.68701
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
0 50 100 150 200 250
Z-Sc
o
r
e
Fe / 2L Standard
R² = 0.7386
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
0 20 40 60 80 100
Z
-
Sc
o
r
e
Mn / 2L Standard
2010
Study
Well No.
Fe,
mg/l
Mn,
mg/l
Fe x
Std
Log Fe
x Std
Mn x
Std
Log Mn
x Std
MW-1 11.74 1.06 39.13 1.593 21.2 1.326
MW-2 6.37 0.63 21.23 1.327 12.6 1.100
MW-3 12.33 0.04 41.1 1.614 0.8 -0.097
PZ-1 3.83 4.43 12.77 1.106 88.6 1.947
PZ-2 11.69 4.11 38.97 1.591 82.2 1.915
PZ-3 3.02 0.56 10.07 1.003 11.2 1.049
PZ-4 26.28 2.16 87.6 1.943 43.2 1.635
PZ-5 30.2 3.16 100.67 2.003 63.2 1.801
PZ-6 69.14 3.46 230.47 2.363 69.2 1.840
PZ-7 23.6 0.43 78.67 1.896 8.6 0.934
PZ-8 31.94 0 106.47 2.027 0 n/a
PZ-9 6.92 0.84 23.07 1.363 16.8 1.225
PZ-10 6.96 0.55 23.2 1.365 11 1.041
PZ-11 1.41 0.02 4.7 0.672 0.4 -0.398
PZ-12 10.3 0.25 34.33 1.536 5 0.699
PZ-14 1.52 0.33 5.07 0.705 6.6 0.820
PZ-15 0.68 0.22 2.27 0.356 4.4 0.643
PZ-16 2.39 0.26 7.97 0.901 5.2 0.716
PZ-17 2.29 0.09 7.63 0.883 1.8 0.255
PZ-18 6.16 0.08 20.53 1.312 1.6 0.204
PZ-19 3.14 0.57 10.47 1.020 11.4 1.057
Mean 12.95 1.11 43.16 1.361 22.14 0.986
Median 6.92 0.55 23.07 1.363 11.00 1.045
Variance 260 2 2887 0.268 821 0.439
Std Dev 16.12 1.43 53.73 0.517 28.65 0.662
Skew 2.40 1.45 2.40 0.012 1.45 -0.340

10

Figure 6.-- Probability plots of log-transformed values of (Fe 2L Standard) and (Mn / 2L Standard) for the 2010 study samples.
Conformance with requirement 1 for compliance samples will have to be assessed by periodically determining
their log transformed values and plotting their distribution compared to the background distribution.

2. Temporal Stationarity of Samples
Conformance with Requirements 1 and 2 above will require the periodic assessment of time trends in
both background and compliance samples to assess whether such trends are consistent with each being
similarly distributed. The evaluation of the background and compliance samples should be evaluated for
temporal trends using regression and/or analysis of variance. These analyses will not be possible until a
sufficient number of compliance (and background) samples are available.

3. Spatial Stationarity of Samples
Examination of the spatial patterns of the log transformed values from the 2010 for Fe shows that
concentrations of Fe were elevated in the northwest portion of the property and Mn concentrations were
elevated in the northern portion of the property as shown in Figure 7. These patterns are likely the
result of increased weathering and leaching of the soils and saprolite from the uplands at the north end of
the property to the lowlands at the southern part of the property. These patterns are not apparently
correlated with either the presence or absence of application fields or with the modeled concentrations of
the arbitrary constituent shown in Figures 4 through 4.
R² = 0.98704
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
0.000 0.500 1.000 1.500 2.000 2.500
Z
S
c
o
r
e
Log (Fe / 2L Standard)
R² = 0.97568
-2
-1.5
-1
-0.5
0
0.5
1
1.5
-0.500 0.000 0.500 1.000 1.500 2.000 2.500
Z
-
Sc
o
r
e
Log(Mn / 2L Standard)

11

Figure 7.-- Log-transformed multiple of Fe (left panel) and Mn (right panel) multiples of the 2L Standards for samples from the 2010 study.
A similar spatial variability assessment should be made using new background data and compliance data
once a samples have been collected for at least one year on the current compliance schedule.

To further assess the spatial distribution of Fe and Mn, the log-transformed values of their respective
multiples of the 2L standards are plotted against each other for the 2010 study samples in Figure 8.
While there is a general trend in this relationship, the correlation coefficient between them is very low,
indicating a very weak relationship.

12

Figure 8.-- Dissolved Fe and Mn plotted against each other showing little correlation between them.
4. Statistical Outliers
The EPA guidance document lists two screening tools (Probability and Box Plots) and two formal
outlier tests (Dixon’s and Rosner’s) to identify statistical outliers8. The probability plots shown in
Figure 6 for the samples from the 2010 study show that there are no apparent outliers for the log-
transformed data for either Fe or Mn. Because samples from multiple time periods are not available for
the 2010 study samples, Box Plots to compare the values are not appropriate. However after a sufficient
number of additional background and compliance samples are available they may be useful in
identifying any outliers. Because there do not appear to be any statistical outliers for either the log-
transformed Fe or Mn data shown in Figure 6, it does not seem appropriate to apply either parameter.

5. Use of Parametric Methods
Using parametric methods to assess compliance with background requires that the background and
compliance data are both drawn from normal distributions or that the data can be transformed to normal
distributions. As shown in Figure 6 both Fe and Mn are log normally distributed and therefore at least
the data from the 2010 study meet this requirement.

6. Minimum Number of Background Samples
The EPA guidance document states that at least 8 samples should be available to establish background
for the use of prediction intervals for compliance assessment9. As few as three background observations
can be used to compute compliance but would result in a very large upper prediction limit for
background and would limit the statistical power of the test.

8 USEPA Unified Guidance document, Chapter 12.
9 USEPA Unified Guidance Document, p. 18-4.
R² = 0.1431
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
0 1 2 3 4 5
Lo
g
(
M
n

/

2
L

S
t
a
n
d
a
r
d
)
Log(Fe / 2L Standard)

13

Although DEQ has determined as previously stated that the sample analyses from the 2010 study cannot
be used by themselves to establish background, it is our professional opinion that that dataset as well as
samples from the 1990 study can and should be use in conjunction with additional samples to achieve
this objective. As demonstrated in the previous five sections the 2010 dataset is a) larger than the
minimum of 8 required; b) shows that parametric tests for compliance can be used if the data is log-
transformed; c) shows that the spatial variability in Fe and Mn is the result of natural variability and not
the result of past applications to fields; and d) apparently does not contain statistically significant
outliers. The recommended monitoring plan utilizes this information from the 2010 samples in
conjunction with additional background samples to be obtained from new permanent background
monitoring wells.

With the exception of compliance well MW-B3, none of the existing wells on site meet the necessary
criteria to establish background. MW-B1 is the only well up-gradient of the fields. The remaining
compliance wells (MW-B-8 and MW-B9 and the three other permanent wells remaining on site (MW-1,
MW-2, and MW-3) are down gradient of the fields and therefore do not meet the DEQ criteria for
background wells going forward. However, data from the 2010 study for MW-1, MW-2, and MW-3 can
and should be use as part of the overall dataset used to establish background. The modeling analysis
shown in the previous section showed that there is the potential for Fe and Mn to have migrated in some
concentrations to these wells as the result of applications in 2014 and 2015 and therefore these and
future data from these wells should be excluded from the background analysis.

Because Fe and Mn were not required compliance parameters prior to the issuance of the current permit,
there is no data from the three compliance wells prior to 2015 for these parameters that could be used to
establish background.

a) Additional Background Wells
This plan recommends the installation and sampling of new wells at five (5) sites and sampled twice at 6
month intervals be used to establish background concentrations for iron and manganese. These sites
were selected based upon the transient model analyses discussed above the are shown on Figures 2
through 4 and were chosen to meet the criteria listed in the DEQ and EPA guidance. The coordinates of
these sites are shown in Table 2 below.

Table 2.-- Coordinates of Proposed Background Monitoring Wells.
Type 1 monitoring wells should be constructed at these sites that are screened from the depth of the
seasonal high water permanent watertable to the top of PWR. Based upon the 2009 S&EC
hydrogeologic report for the site the new wells will be approximately 25 feet deep and have ten (10) feet
of well screen. The preferred well construction method should be sonic or air rotary drilling to
eliminate blinding off of the formation by drilling muds with hydraulic rotary or smearing of the
formation by hollow stem auger methods.
Well No Easting Northing
P-MW-1 2126155 691193
P-MW-2 2124156 688177
P-MW-3 2123614 686726
P-MW-4 2125044 688180
P-MW-5 2126427 689422

14

The wells are to be constructed using new threaded 2-inch diameter PVC casing and wire-wound screen
with a number 10 (0.01 inch) opening. The wells are to be completed with a graded sand pack installed
in the annulus between the well screen and borehole wall from the bottom of the boring to two feet
above the top of the screened interval. A bentonite seal at least 1 foot thick is to be placed on top of the
sand pack and a concrete seal placed above it to the land surface. The wells are to be completed with
above-ground, lockable, protective metal well casings.

The new background wells should be developed using industry standard procedures as documented in
the DEQ guidance document. Pumping, surging, and bailing should be used in an effort to develop the
sand pack used so as to minimize the potential for fine sediment to enter the wells during the sampling
events. Development should continue until the produced water is visibly clear and preferably has a
turbidity of 10 NTU or less or the turbidity levels are stable (three consecutive turbidity measurements
do not vary by more than 10%).

b) Sampling to Establish Background
The newly constructed background wells and the three compliance wells should be sampled on a bi-
monthly basis for the first six months following their installation to develop an adequate sample
population for background assessment. Thereafter, these wells should be sampled on the same schedule
used for the existing three compliance wells (March, July, and November) for one year to assess any
longer term time trends. Low flow purging and sampling of all wells should be used to conform with the
DEQ guidance document10. Low flow well purging should continue until turbidity levels are less than
10 NTU or vary no more than 10% and field measured pH and water temperature are similarly stable.

c) Initial Sampling Methodology Assessment
An initial evaluation of low-flow purging and sampling was conducted of the three existing compliance
wells (MW-B-3, MW-B-8, and MW-B9) on February 5, 2016 by CORPUD staff using procedures
recommended by Eagle Resources to assess the ability to implement the procedures for obtaining valid
metal samples recommended by DEQ. Low flow well purging was conducted for approximately 30
minutes with pH, temperature and turbidity measurements made at approximately 7 minute intervals.
The wells were purged with the dedicated bladder pumps installed in each well controlled with a
GeoControl Pro system which filled the bladder for 20 seconds and discharged for 10 seconds, resulting
in a flow rate of 0.375 gallons per minute. The field measurements for this purging event are shown in
Table 3.

Water samples were taken at the end of the purging in pre-acidified sample containers supplied by the CORPUD
laboratory and the results of these analyses are shown in Table 3. It is apparent that the DEQ requirements for
low flow purging and sampling can be implemented for the compliance wells. While the turbidity in well MW-
B9 was slightly greater than 10 NTU, subsequent measurements were stable within 10% of the initial value.

10 NC Division of Water Quality, May 13, 2013: Aquifer Protection Section Policy for Metals Determinations Required by Title
15A North Carolina Administrative Code, Subchapter 2L.

15

Table 3.-- Results of purging of compliance wells on February 5, 2016 and laboratory analyses for dissolved Fe and Mn in samples taken
at the end of purging..
Recommended Background Determination Methodology
The following steps are recommended to implement the determination of background concentrations of
As, Fe, and Mn at the Wrenn Road Site:

1. Install and develop the five (5) new background monitoring wells as recommended herein;

2. Sample the background and compliance wells bi-monthly for six (6) months following the
installation and development of the new wells. The sampling should follow the recommended
low-flow purging, and field analysis for pH, Conductivity, Turbidity, and Temperature. Samples
taken should be analyzed in the CORPUD laboratory for As, Fe and Mn This will provide a
background sample size of 15 (5 wells x 3 samples) for each constituent. One duplicate should
be taken from one of the background wells that is randomly selected for each sampling round;

3. Prepare probability plots of the 15 sample results for each constituent using the log transform of
the raw values; and visually compare to the plots for the 2010 samples;

4. Conduct One-way Analysis of Variance (ANOVA) on the log-transformed values to assess
whether the new background results are from the same population as the 2010 samples;

5. If the ANOVA shows that the new and 2010 samples are from the same population, pool both to
1 8 16 23
0.38 3.00 6.00 8.63
pH 4.81 4.55 4.57 4.59
Temp Deg C 15.20 15.6 15.8 15.80
NTU 0.20 1.30 1.35 0.95
0.111
< .05
43.4
pH 4.80 4.74 4.83 4.79
Temp Deg C 14.80 15.1 15.1 15.10
NTU 2.43 2.00 1.48 1.86
0.109
0.148
189
pH 5.61 5.15 5.06 4.97
Temp Deg C 14.20 13.8 13.9 13.90
NTU 14.90 13.40 13.10 13.30
0.57
< .05
64.2
Dissolved Fe (mg/l)
Dissolved Mn (mg/l)
Conductivity (umhos/cm)
MW-B-9
Elapsed Time, Min
Purge Volume Gal
MW-B-3
MW-B-8
Dissolved Fe (mg/l)
Dissolved Mn (mg/l)
Conductivity (umhos/cm)
Dissolved Fe (mg/l)
Dissolved Mn (mg/l)
Conductivity (umhos/cm)

16
define the background statistics to use in compliance monitoring; or

6. If the ANOVA shows that the new and 2010 samples are not from the same population, use only
the new samples to define the background statistics to use in compliance monitoring; and

7. Sample the new background wells for one year on the same schedule used for the compliance
wells (March, July, and November) to evaluate any time trends in As, Fe, Mn to consider in
compliance assessments. Log transformation should be applied to all these data.

Conclusions
A recommended methodology for establishing the background statistics for the concentrations of
Arsenic (As) Iron (Fe) and Manganese (Mn) in groundwater at the Wrenn Road facility that can be used
in assessing compliance in the three compliance wells monitored at the site under the currently issued
permit WQ0002708. This methodology was prepared in response to a condition of the issuance of the
permit by NC DEQ.

Information on As, Fe, and Mn concentrations is available from the 2010 study at the site that was
collected before application of residual effluent from the Dempsey E. Benton Water Treatment Plant
began in 2014 under the permit. However, the wells used to collect these samples were temporary and
could not be re-sampled and the sample purging and collection methods used for that study were not
necessarily conformant with DEQ guidance for metals evaluation that was published in 2012 and 2013.
Consequently, additional background wells are recommended to be installed to supplement the 2010
data.

Five additional background wells are recommended at sites where modeling analyses conducted as part
of this plan showed that concentrations of mobile constituents contained in effluent applied in 2014 and
2015 were not likely to have reached.

The plan recommends sampling the new wells bi-monthly for six months to provide an adequate sample
size for assessing background concentrations of As, Fe, and Mn. To assess the additional value
provided by also considering the results from the 2010 study, statistical evaluations are recommended to
ascertain if data from the new wells is from the same population as that from the 2010 study. If so, all
the data should be pooled to provide a more robust sample size to establish the distributions and
statistics to use in compliance assessment. If these tests show that the new and 2010 data are not from
the same population only the new data should be used. This assessment concluded that to enable the use
of parametric tests for compliance that the raw As, Fe, and Mn concentrations should be log-
transformed.

To assess any time trends in background values of As, Fe, and Mn it is recommended that the
background wells be sampled for one year on the same schedule used for the compliance wells. The
background wells should be maintained in such as a condition that they can be resampled following this
period if necessary.

B
Responses to DEQ
Comments – Provided
October 7, 2017

Eagle Resources, P.Å.
215 West Moore Street Southport, NC 28461
919-345-1013 www.eagleresources.com

Rick Bolich, L.G.
Assistant Supervisor
N.C. Dept. of Environmental Quality
Division of Water Resources
Water Quality Regional Operations Section
Raleigh Regional Office
3800 Barrett Drive
Raleigh, NC 27609

[e-mail]

October 7, 2017

Subject: Groundwater Monitoring Plan for City of Raleigh Wrenn Road Facility Permit WQ0002708.

Dear Rick;
This letter responds to your email dated May 2, 2017 to Chris Brown of HDR regarding the location of
proposed new monitoring wells to establish ambient concentrations of iron and manganese in
groundwater at the Wrenn Road Facility. Our response to the issues you provided in that email are
attached.

Please contact us if you need any further information on this matter. We are available to meet with you
if necessary to discuss any additional information that you may need to approve the monitoring plan.

Sincerely yours,

Eric G. Lappala, P.E., P.H.

Attachment:
Response to additional information request

2

Comment:
The proposed background wells P-MW-1 and P-MW-5 appear to be in a topographically upgradient areas that
would be good locations for background assessment of groundwater conditions.

P-MW-2, P-MW-3. and P-MW-4 are not in locations suited to be background locations. They may be suitable
monitoring stations for site conditions affected by lagoon and spray field activities, but these locations are not
representative of background concentrations as they appear to be hydraulically downgradient of the waste
application areas. DWR recommends moving these two wells to a location that is unlikely to be impacted by
waste application.

Response:
The groundwater flow and transport modeling performed for this site demonstrate that all wells chosen to establish
background conditions, including P-MW-2, P-MW-3, and P-MW-4, are unlikely to have been impacted by the
application of water treatment residuals, even if they are within the boundaries of the facility. The objective of the
proposed monitoring plan is to establish statistically significant ambient background conditions that include any
contribution from applied wastewater effluent during that period.

The site was used previously by the Town of Garner and operated by the City of Raleigh to dispose of treated
wastewater effluent from 1989 through 2008 under permit WQ0002708 (Permit).
• Sampling and analysis for iron and manganese in groundwater was not required under that permit.
• The Eagle Resources 2010 study used to support the modification of the Permit detected elevated
concentrations of iron and manganese in temporary monitoring wells that were located within and down
gradient of fields that had been used for wastewater effluent from 1989 to 2008.
• Therefore, any concentrations of these constituents that are currently in groundwater are the result of both
their natural occurrence and any concentrations that may have been present in the wastewater effluent applied
under the permit from 1989 through 2008.

The application of water treatment residuals from the Dempsey E. Benton Water Treatment Plant under the amended
permit that was issued in 2012 began in 2014. The three-dimensional groundwater flow and transport model used in
the 2010 report was updated and used to assess the likely extent of migration of iron and manganese may have
occurred as the result of the application of water treatment residuals.

As documented in the 2010 report the migration of both iron and manganese in groundwater is influenced by the
complex geochemical interaction of these constituents with the soils, saprolite and weathered bedrock that underlie
the site. These interactions all act to attenuate the migration of iron and manganese relative to the migration of
groundwater via a variety of sorption processes. However, to provide the likely maximum extent of their migration
from the application of water treatment residuals, the updated model did not include any of these attenuation
processes.

The DEQ guidance document on establishing ambient background also requires that a statistically valid data set be
present that accounts for the spatial variability hydrogeologic conditions as well concentrations of the regulated
constituents that were present prior to the application of water treatment residuals. Because of the size and
complexity of the Wrenn Road site, it therefore is necessary to include monitoring sites that are within the boundaries
of the site and that may be apparently hydraulically down gradient of some application fields but that have not been
impacted by the application of water treatment residuals.

3

All the proposed monitoring wells locations were selected to meet above criteria. Locating additional wells only at
topographically up-gradient locations of all fields will not meet the requirement to account for this spatial variability
and account for presence of iron and manganese interior to the site that were detected in samples taken for the 2010
report that may have included a contribution from the application of wastewater effluent prior to 2008. Therefore,
we believe that it is scientifically appropriate to install monitoring wells at the proposed locations in order to establish
background conditions.

Comment:
Please use caution if you intend to use groundwater quality data from the 2010 Eagle Resources study and report
to establish background metals concentrations as some of the wells in this study had turbidity in excess of the
levels recommended in the NCDEQ July 2012 “Evaluating Metals in Groundwater at DWQ Permitted Facilities:
A Technical Assistance Document for DWQ Staff” as mentioned in previous correspondence. Please also note
filtered samples are not acceptable for use in establishing metals concentrations at permitted facilities in
accordance with the May 13, 2013 policy memo by Jay Zimmerman, “Aquifer Protection Section Policy for Metals
Determinations Required by Title 15A, North Carolina Administrative Code, Subchapter 2L”.

Response:
We intend to use only data that we deem in our professional opinion to be representative of background
conditions.

Comment:
DWR also recommends that any new compliance monitoring wells used to monitor potential impacts from waste
applications be placed at the review or compliance boundary.

Response:
We will consult with DWR on the location of any new compliance wells if they become necessary.

C
Ground Water Monitoring
Plan Resubmittal – Submitted
on December 14, 2018

555 Fayetteville Street, Suite 900, Raleigh, NC 27601
[phone]
hdrinc.com

Transmittal
Date: Friday, December 14, 2018
Project: City of Raleigh Wrenn Road Facility
To: Rick Bolich, L.G., DEQ
From: Chris Brown, PE, HDR
Subject: Groundwater Permit

We are sending you: ☒ Attached ☐ Under separate cover via the following items:
☐ Shop drawings ☐ Prints ☐ Plans
☐ Samples ☐ Specifications ☐ Copy of letter
☐ Change Order ☐ Other:

Copies Date No. Description
1 Dec 13 2018 Letter from Eagle Resources – Relocated Wells

These are transmitted as checked below:
☒ For your approval ☐ Approved as submitted ☐ Resubmit
☒ For your use ☐ Approved as noted ☐ Submit
☒ As requested ☐ Returned for corrections ☐ Return
☒ For review/comment ☐ Other:
☐ For bids due ☐ Prints returned after loan to us

Remarks: Mr. Bolich –

HDR Engineering, Inc. of the Carolinas (HDR) is pleased to provide DEQ with the above item. This is
a follow up to comments received at our Oct 2017 meeting. The team has been working with the
adjacent land owner on acquisition of property.

We would like to meet in Jan 2019 to discuss a path forward.

Please let us know if you have any questions.

Copy to: Dennis Lassiter, Chris Phelps, Whit
Wheeler, Jesse Walker, Tracy McLamb -
City of Raleigh; Eric Lappala, Eagle
Resources; Samantha Black, Manish
Bhandari - HDR

Signed: Chris Brown 919.677.9350
[e-mail]

Eagle Resources, P.Å.
215 West Moore Street Southport, NC 28461
919-345-1013 www.eagleresources.com
Rick Bolich, L.G.
Assistant Supervisor
N.C. Dept. of Environmental Quality
Division of Water Resources
Water Quality Regional Operations Section
Raleigh Regional Office
3800 Barrett Drive
Raleigh, NC 27609

[e-mail]

December 13, 2018

Subject: Groundwater Monitoring Plan for City of Raleigh Wrenn Road Facility Permit WQ0002708

Dear Rick,

This letter transmits the revised locations of the four (4) proposed background monitoring wells for the
subject facility that are shown on the attached map. Wells PMW-2 and PMW-3 will be installed on
property recently acquired by the City of Raleigh. Well PMW-3 is to be accessed for installation from
the adjacent subdivision which has provided permission for same. The location of PMW-1 has not
changed from the original monitoring plan We have moved the location of PMW-4 to the location
shown on the attached map to provide better access for drilling equipment.

We are available at your convenience to meet to discuss the monitoring plan and these locations if it is
necessary.

Sincerely yours,

Eric G. Lappala, P.E., P.H.
Attachments: Proposed monitoring well location map

City of
Raleigh
Public
Utilties
Department
Eagle Resources, P.A.
215 West Moore Street
Southport, NC 28461
919-345-1013
[e-mail]
Project No.
24041.1
1
FIGURE
Approved: EGL
Design data and recommendations included herein are provided as a
matter of information and should not be used for final design. Rely only on
hard copy bearing consultants original seal and signature
Location of proposed background moniitoring wells
Wrenn Road Facilty.
Date: 11/28/18
Proposed Background Monitoring Wells
Property Boundaries (Wake County GIS)
EXPLANATION
Well No.Easting Northing
PMW-1 2126151.11 691215.39
PMW-4 2125522.18 687848.49
PMW-2 2124505.08 691694.17
PMW-3 2121970.6 688486.31

D
Minutes from Resubmittal
Discussion Meeting –
Meeting Held on January 31,
2019

Meeting Minutes
Project: City of Raleigh – Wrenn Road Facility Ground Water Monitoring Plan
Subject: Meeting with City and DEQ
Date: Thursday, January 31, 2019
Location: DEQ Offices, 3800 Barrett Drive
Attendees: Chris Phelps – City of Raleigh
Rick Bolich – DEQ
Brion Byers – DEQ
Eric Lappala – Eagle Resources
Samantha Black – HDR
Manish Bhandari – HDR
Chris Brown – HDR

Goal of the Meeting
The goal of this meeting was to gain verbal approval of the Wrenn Road Facility Ground Water
Monitoring Plan so the City may proceed to the implementation and monitoring phase. An
additional goal was to make DEQ aware of changes that may come to the existing Wrenn Road
Facility following the future expansion of Interstate-540 (I-540).
History of the Wrenn Road Facilties Ground Water Monitoring Plan
A brief history of the Wrenn Road Facility Ground Water Monitoring Plan was provided during
the meeting as follows:
 The current permit (WQ0002708) was issued in 2015, and allowed the continued
operation of the Wrenn Road Facility. Part of this permit was the requirement that the
City monitor ground water wells for manganese, iron, and arsenic.
 In February 2017, a revised monitoring plan was submitted to DEQ.
 In May 2017, comments on the revised plan were received by DEQ.
 In October 2017, the City/HDR provided responses to DEQ comments, and a meeting
was held with the City, DEQ, and HDR to discuss these responses. Changes to some of
the background wells were requested by DEQ during this meeting.
 In 2018, the City obtained a parcel of land adjacent to the Wrenn Road Facility. This
parcel provided options for locating background wells. This parcel will provide easier
access to monitoring well #3.
 In December 2018, revised background well locations were submitted to DEQ for review.
These locations were selected based on fieldwork conducted by Eagle Resources and
the well driller. Two well locations were added to the west of the Wrenn Road Facility.

Revised Well Locations
There are four proposed monitoring wells (PMWs). PMW -4 was relocated to avoid a drilling
access issue, and it is now on the access road. DEQ is interested in the ground water flow
directions for PMW -4, and requested a 5-ft contour map of this site. Additionally, a water table
map and water levels were requested.
Wells will be drilled into partially weathered rock, and are not considered bedrock wells. It is
estimated that the depth of these wells will be less than 50 feet. The nearby subdivision ground
water well might influence PMWs if they are to be drilled into partially weathered rock. It was
suggested that a monitoring device be put in to observe the diurnal influence of the subdivision
well. The partially weathered rock is a relatively high permeability, and there is no significant
change in water level based on a recent study. The screening level of the PMWs will be from
the bottom, across the water table.
Impacts of I-540 to the Wrenn Road Facility
In the future, I-540 will be expanded on a portion of the Wrenn Road Facility. It is expected that
this expansion will result in the abandonment of at least one MW, consumed 15 to 16 acres of
irrigation land, and change the compliance boundary. The I-540 design-build project is in the
early stage of design, and it is anticipated that it will be one year until the design is complete. A
conceptual drawing of where I-540 will be located was provided in the agenda. The City will deal
with the changes caused by the I-540 expansion project when the design is closer to
completion. The PMWs will not be impacted by I-540.
It may be beneficial to submit the ground water monitoring plan once changes from the I-540
project are established since construction will impact the water table. However, the City will
need to submit a permit modification after the new compliance boundary is established.
Alternatively, having a plan in place prior to I-540 construction may be beneficial as well to get
background data collected before construction for comparison purposes.
The City plans to wait to abandon wells impacted by I-540 until they can no longer use
associated the spray irrigation area. Although 15 to 16 acres of land will be lost due to the I-540
expansion, the City currently has excess capacity. However, the permit will still need to be
modified to reflect the new capacity.
Action Items and Next Steps
 HDR/Eagle Resources to provide existing subdivision water well locations, ground water
well levels, well depth, and a contour map to DEQ.
 DEQ will review information and generate a ground water flow map.
 HDR to resubmit the revised Wrenn Road Facility Ground Water Monitoring Plan to DEQ
for review.
These minutes were prepared by Samantha Black with HDR> Please provide comments within
5 days of receipt to [e-mail] or 919-232-6638.

E
Water Well Locations for
Subdivision Adjacent to the
Wrenn Road Facility

1

Appendix E – Water Well Locations for
Subdivision Adjacent to the Wrenn Road Facility
HDR has identified three wells located within the Glen Creek Community:
1. Well 1: One drinking water well is completely developed, and is located on the north side
of the community (Figures 1 and 2).
2. Well 2: A second drinking water well has been drilled, but is not currently in use, and is
located the south side of the community (Figures 3 and 4).
3. Well 3: The third well is an irrigation well, which supplies irrigation water to the
community (Figures 5 and 6).
Table 1 provides a summary of these community wells, and the following figures show
photographs of wells and their locations relative to the closest proposed monitoring wells
(PMWs).
Table 1. Glen Creek Community Wells
Well Use Latitude, Longitude Closest PMW
1 Drinking Water 35.6466, -78.5855 PMW -2
2 Drinking Water 35.6363, -78.5937 PMW -3
3 Irrigation Water 35.6503, -78.5803 PMW -2

Figure 1. Existing Drinking Water Well Located on the North Side of the Glen Creek Community
2

Figure 2. Existing Drinking Water Well Location Relative to PMW-2

Figure 3. Future Drinking Water Well Located on the South Side of the Glen Creek Community

Figure 4. Future Drinking Water Well Location Relative to PMW-3
3

Figure 5. Existing Irrigation Well Located on the North Side of the Glen Creek Community

Figure 6. Irrigation Well Location Relative to PMW-2

F
Ground Water Well Levels

City of Raleigh Ground Water Monitoring Plan
Wrenn Road Facility
Ground Water Well Levels
B-3 MP Elev 346.00 B-8 MP Elev 226.46 B-9 MP Elev 247.94
Date DTW WL EL Date DTW WL EL Date DTW WL EL
3/9/2017 19.70 326.30 42803.00 20.50 205.96 42803.00 11.20 236.74
7/5/2017 20.60 325.40 42921.00 21.10 205.36 42929.00 12.10 235.84
11/7/2017 22.80 323.20 43046.00 23.60 202.86 42937.00 12.30 235.64
3/8/2018 22.00 324.00 43167.00 22.30 204.16 43046.00 12.20 235.74
7/5/2018 22.40 323.60 43286.00 23.00 203.46 43167.00 11.40 236.54
7/12/2018 22.60 323.40 43293.00 23.20 203.26 43286.00 12.60 235.34
11/8/2018 21.50 324.50 43412.00 22.70 203.76 43293.00 12.50 235.44

G
Contour Map of Proposed
Monitoring Well Locations

City of
Raleigh
Public
Utilties
Department
Eagle Resources, P.A.
215 West Moore Street
Southport, NC 28461
919-345-1013
[e-mail]
Project No.
24041.1
1
FIGURE
Approved: EGL
Design data and recommendations included herein are provided as a
matter of information and should not be used for final design. Rely only on
hard copy bearing consultants original seal and signature
Proposed background moniitoring wells, existing
compliance wells, topography, modeled steady state
watertable elevations, and measured water level
elevations in July 2018, Wrenn Road Facilty Date: 02/02/19
Compliance Wells and July 2018 Water Level
Background Wells
Property Boundaries (Wake County GIS)
Land Surface Elevation
Modeled Steady State Watertable 2014
EXPLANATION
Well No.Water Table Elev
MW-B-9 235.34
MW-B-8 203.26
MW-B-3 323.4

This page intentionally left blank

HDR Engineering, Inc. of the Carolinas
555 Fayetteville Street
Suite 900
Raleigh, North Carolina, 27601
919-232-6600

NCBELS Number F-0116
hdrinc.com
© 2019 HDR, Inc., all rights reserved

F)Z
hdrinc.com
November 19, 2019
Mr. Rick Bolich
NC Department of Environmental Quality
Division of Water Resources
Water Quality Regional Operations Section
Raleigh Regional Office
3800 Barrett Drive
Raleigh, NC 27609
Re: Ground Water Monitoring Plan
Permit No. WQ0002708
City of Raleigh Wrenn Road Facility Wastewater Irrigation System
Wake County, North Carolina
Dear Mr. Bolich,
On behalf of the Public Utilities Department I Raleigh Water, we are submitting the attached
Installation and Testing of Background Wells report prepared by Eagle Resources, P.A., under
subcontract to HDR. This report was prepared to satisfy requirements of the Ground Water
Monitoring Plan for the Wrenn Road Facility Wastewater Irrigation System Package, submitted to
NC DEQ DWR in February 2019, and approved in April 2019.
Should you have any questions, please do not hesitate to call us at 919-232-6657.
Sincerely,
HDR Engineering Inc. of the Carolinas
Chris Brown, PE
Project Manager
Enclosures
cc: Chris Phelps, Public Utilities Department I Raleigh Water
Dennis Lassiter, Public Utilities Department I Raleigh Water
Whit Wheeler, Public Utilities Department I Raleigh Water
Eric Lappala, Eagle Resources
Samantha Black, HDR
Manish Bhandari, HDR
555 Fayetteville Street Suites 900 & 210, Raleigh, NC 27601-3034
[phone]

Eagle Resources, P.Å.
215 West Moore Street, Southport, NC 28461
919-345-1013 www.eagleresources.com

Chris Brown, P.E.
HDR
555 Fayetteville Street
Suite 900
Raleigh, NC
27601

11/08/19

Subject: Wrenn Road Background Monitoring Well Installation Report

Dear Chris;
This letter transmits the updated data and information from my observations of the installation and
testing of the four background monitoring wells at the Wrenn Road facility. These wells were installed
as part of the monitoring program to establish background concentrations of Fe, Mn, and As in
groundwater in accordance with the monitoring plan documented in our report dated February 2017 and
approved by the NC Division of Water Resources, Raleigh Regional Office (NCDWR RRO). This
update includes the results of turbidity testing on PMW-3 and PMW-4 that was conducted on 11/06/19
at your request.

Sincerely yours,

Eric G. Lappala, P.E., P.H.

Attachment: Well Installation Report7

Installation and Testing of Background Wells
City of Raleigh Wrenn Road Facility, Garner, NC

Prepared for:

HDR
and
City of Raleigh
Public Utilities Department

September 25, 2019
(Updated 11/08/19)

Eric G, Lappala, P.E., P.H.

EAGLE RESOURCES, P.A.
215 WEST MOORE STREET
SOUTHPORT, NC 28461

i
Table of Contents
Introduction ........................................................................................................................... 1
Well Installation ..................................................................................................................... 1
Turbidity Testing .................................................................................................................... 2
Pump Testing ......................................................................................................................... 4
Sampling Protocol Recommendations .................................................................................... 5
Attachment 1 Photos and Description of Drill Cutting Samples .............................................. 7
PMW-1 ................................................................................................................................... 7
Attachment 2 Well Completion Records ................................................................................. 11
Attachment 3 Pumping Test Analysis Curves .......................................................................... 15

Figures
Figure 1.-- Locations of Installed Background Monitoring Wells. ................................................. 6

Tables
Table 1.-- Well Completion Information. ........................................................................................ 1
Table 2.-- Turbidity measurements in PMW-1. .............................................................................. 2
Table 3.-- Turbidity measurements in PMW-2. .............................................................................. 2
Table 4.-- Turbidity measurements in PMW-4. .............................................................................. 3
Table 5.--Pumping and recovery test analysis results. .................................................................... 5

1

Introduction
This report documents the installation, turbidity testing, water level measurements, and estimated aquifer
hydraulic parameters for four wells installed at the Wrenn Road facility. These wells were installed to be
used as part of the program1 that has been approved by NC DWR to establish background concentrations
of iron (Fe), Manganese (Mn), and Arsenic (As) to use as alternatives to the NC 2L groundwater standards
for these constituents. The locations of these wells are shown on Figure 1 and were determined by GPS
by Eagle Resources.

Well Installation
The wells were all installed by Geologic Exploration of Statesville, NC under the direction and contract
to HDR. The installation dates and completion information provided by driller are shown in Table 1. At
the direction of Eagle Resources, all wells were drilled and completed with depths that extended at least
into the Partially Weathered Rock (PWR) that underlies the soil and saprolite at all locations. All wells
were drilled with a Geoprobe™ track-mounted drill rig that had the capabilities for both down-hole air-
percussion (Air) and hollow-stem auger (HSA) methods.

Table 1.-- Well Completion Information.
Well PMW-4 was installed to the completed depth using Air but HSA was used to complete the well as
the open hole caved at a depth of approximately 22 feet. All other wells were installed using the HSA
method. Completion of all wells was accomplished by installation of screen, casing, sand pack, bentonite,
and grout as the HSA was removed. Grout was installed by pumping with a tremie pipe to assure no
bridging.

All wells were developed by the driller by surging and pumping with a submersible pump until the pump
discharge was visibly clear.

Soil samples were collected by either the driller or Eagle Resources at 5 to 10-foot intervals or significant

1 Eagle Resources, 2017: Proposed Monitoring Plan to Establish Background Concentration of Iron and Manganese at the
Wrenn Road Sprayfields Wake County, NC.
PMW-1 PMW-2 PMW-3 PMW-4
Date Drilled 8/13/19 8/14/09 8/26/19 8/13/19
Drill Method HSA HSA HSA Air/ HSA
Drill Diameter In 10/6 8 8 8
Depth Ft 43 20 16 74
Screen Top Depth Ft 33 10 6 64
Screen Bottom Depth Ft 43 20 16 74
Sand Pack Top Depth Ft 31 8 4 61
Sand Pack Bottom Depth Ft 43 20 16 74
Bentonite Top Depth Ft 29 6 3 58
Bentonite Bottom Dept Ft 31 8 4 61
Grout Top Depth Ft 0 0 0 0
Grout Bottom Depth Ft 29 6 3 58
Static Water Level Depth Driller Ft 22 5 2 22
Stickup Ft 3.0 3.0 3.7 2.9
Depth to Water from TOC (8/26/19)Ft 23.63 7.99 7.60 20.22
Well ID
Units

2
change in the visual appearance of drill cuttings during drilling. The sample descriptions and photos of
the sampled materials are shown in Attachment 1. The logs of materials encountered by the driller and
well construction details are included in the Well Completion Records (Forms GW-3) and are included as
Attachment 2.

Turbidity Testing
Wells PMW-1, PMW-2, and PMW-4 were tested for turbidity during pumping on August 26, 2019 by
Eagle Resources. PMW-3 was not tested because it was bit installed prior to the time turbidity testing
equipment having to be returned. However, turbidity testing in this well was completed on 11/06/19 as
discussed below. Pumping was conducted by Geologic Exploration using a downhole submersible pump.
Turbidity measurements were made on samples collected during pumping with a Hanna HI 98703 Portable
Turbidimeter. For wells PMW-1 and PMW-2, pumping continued until the turbidity readings became
stable or were less than 5 NTU. Well PMW-4 was cycled between pumping and recovery in an attempt
to produce stable and low turbidity readings. Pumping rates were determined by using a bucket of known
volume and a stopwatch.

Turbidity readings and chart for each well are shown in Tables 2, 3, and 4.

Table 2.-- Turbidity measurements in PMW-1.

Table 3.-- Turbidity measurements in PMW-2.

1
10
100
1000
0 10 20 30 40
Tu
r
b
i
d
i
t
y
,

N
T
U
Pumping Time, Minutes
PMW-1
1
10
100
1000
0 10 20 30 40 50
Tu
r
b
i
d
i
t
y
,

N
T
U
Pumping Time, Minutes
PMW-2
Pumping Time Turbidity Pumping Rate
Minutes NTU GPM
5 524 0.94
9 21.4 0.94
13 5.47 0.94
20 2.79 0.94
25 1.38 0.94
30 1.05 0.94
Well
PMW-1
Pumping Time Turbidity Pumping Rate
Minutes NTU GPM
2 210 1.41
6 22.9 1.41
10 7.95 1.41
21 4.86 1.41
25 5.78 1.41
35 5.57 1.41
40 4.64 1.41
PMW-2
Well

3

Table 4.-- Turbidity measurements in PMW-4.
On 11/06/19 PMW-3 and PMW-4 were tested for turbidity using a portable downhole submersible pump
and a portable turbidity meter. Pumping from PMW-3 was continuous at an estimated 1 gpm. Pumping
from PMW-4 was cyclic as the measured depth to water in the well was 22.55 feet below the top of casing
and only 25 feet of discharge line was available and after approximately 10 seconds of pumping the water
in the well was drawn down below the pump intake. Consequently, samples were taken after the well was
allowed to recover for approximately 15 seconds. The turbidity readings for these tests are shown in
Tables 5 and 6.

Table 5.-- Results of turbidity testing on PMW-3 on 11/06/19.

10
100
1000
0 20 40 60 80 100
Tu
r
b
i
d
i
t
y
,

N
T
U
Pumping Time, Minutes
PMW-4
Pumping Time Turbidity Pumping Rate
Minutes NTU GPM
1 46.6 nm
5 22.5 nm
10 8.01 nm
15 5.06 nm
20 6.54 nm
25 1.67 nm
30 3.05 nm
Well
PMW-3
(11/06/19)1
10
100
0 10 20 30 40
Tu
r
b
i
d
i
t
y
,

N
T
U
Pumping Time, Minutes
PMW-3 (11/06/19)
Pumping Time Turbidity Pumping Rate
Minutes NTU GPM
2 610 0.84
5 484 0.84
9 394 0.65
17 368 0.56
24 216 0.56
29 254 0.56
38
50
51 184 0.76
57 174 0.60
65 136 0.53
75 213 0.56
80 442 0.56
83 462 0.56
pump off
pump onPMW-4
Well

4

Table 6.-- Results of turbidity testing on PMW-4 on 11/06/19.
Based upon the turbidity readings in PMW-1, PMW-2, and PMW-3 it appears that purging these wells for
at least 30 minutes of continuous pumping should achieve levels consistent with the sampling and analysis
protocol recommended in the approved monitoring program of 10 NTU or less.

The initial turbidity readings in PMW-4 did not stabilize and were not as low as potentially may be
achieved. Subsequent testing on 11/06/19 showed that pumping from the top of the water column in the
well was approximately stable at 20 NTU. Because the dedicated air-lift pump in this well is set at the
bottom of the well, it is recommended that this well be further developed by air-lift pumping and surging
and additional turbidity measurements made if this low level is not observed while purging before
sampling. .

Pump Testing
Although it was not required as part of the approved monitoring program, water level changes during
pumping and recovery cycles of PMW-1, PMW-2, and PMW-4 were recorded by manual measurements
with an electric water level sounder and with a downhole recording transducer that was read at the surface
(In-Situ LevelTroll™ 400).

These water level changes and the corresponding pumping rates were used to evaluate the transmissivity,
hydraulic conductivity, and storage properties of the formation sections in which the wells were screened.
The water level and pumping data were analyzed using AqteSOLV™. The results are summarized in
Table 5. The analysis curves for both the Theis and Neuman analysis methods for unconfined aquifers
are presented as Attachment 3.
Pumping Cycle Turbidity Pumping Rate
No NTU GPM
2 39.3 nm
3 33 nm
4 31.3 nm
5 25.6 nm
6 18.7 nm
7 25 nm
8 18.9 nm
9 26.9 nm
10 28.7 nm
Well
PMW-4
(11/06/19)
10
100
1 3 5 7 9
Tu
r
b
i
d
i
t
y
,

N
T
U
Pumping Cycle
PMW-4 (11/06/19)

5

Table 7.--Pumping and recovery test analysis results.
Sampling Protocol Recommendations
Sampling protocol should meet the requirements of the approved background sampling program for the
site as documented on page 14 of the approved report (footnote 1). Documentation of sampling should
use the spreadsheet developed by HDR.

Well ID Units PMW-1 PMW-2 PMW-3 PMW-4
formation thickness, b ft 21 15 52
oz 18 18 18
gal 0.140625 0.140625 0.140625
sec 9 6 15
min 0.15 0.1 0.25
gpm 0.94 1.41 0.56
Aquifer type Unconfined Unconfined
Method Theis Theis
Transmissivity, T ft^2/d 32 162 1.5
Hydraulic conductivity, K ft/d 1.5 10.8 0.029
Storage Coefficient, S Dim 8.00E-05 0.0025 0.0056
Vertical to Horizontal K, Kz/Kr)Dim 1 1 1
Neuman Neuman Neuman
Transmissivity, T ft^2/d 7.2 131 1.07
Hydraulic conductivity, K ft/d 0.34 8.73 0.02
Storage Coefficient, S Dim 0.009 0.0035 0.02
Pumping rate(s), Q
No test
City of
Raleigh
Public
Utilties
Department
Eagle Resources, P.A.
215 West Moore Street
Southport, NC 28461
919-345-1013
[e-mail]
Project No.
24041.1
1
FIGURE
Approved: EGL
Design data and recommendations included herein are provided as a
matter of information and should not be used for final design. Rely only on
hard copy bearing consultants original seal and signature
Location of installed background moniitoring wells
and compliance wells. Wrenn Road Facilty.
Date: 09/25/19
Monitoring Wells
Background Monitoring Well
Compliance Monitoring Well
Property Boundaries (Wake County GIS)
EXPLANATION

7
Attachment 1 Photos and Description of Drill Cutting Samples

PMW-1

Depth, Ft Description Color
0 -5 Reddish Brown Sandy Soil 10 YR 3/4
5 - 10
Orange Brown Coarse
sandy saprolite 2.5 YR 6/8
10 - 15
Tan saprolite some PWR
fragments, moist 5 YR 6/4
15 -20
Tan saprolite - sandy clay
very moist 10 YR 7/4
20 - 25
Clayey silt slightly sandy
saprolite - saturated 10 YR 7/4
25 - 35 Sample not saved
35 - 40
Clayey silt slightly sandy
saprolite - saturated 10 YR 7/4
40 - 45
Sample from air lift
Weathered Rock, Mica,
and small quartz
fragments 5 YR 6/4
PMW-1

8
PMW-2

Depth, Ft Description Color
5
Brown to tan silty sand
soil and saprolite 10 YR 7/4
10
Dark brown sandy
saprolite minor rock
fragments, moist 10 YR 2/2
15
Dark brown sandy
saprolite minor rock
fragments, moist 10 YR 2/2
20
Dark Brown to green
brown sandy saprolite
minor mica 10 YR 2/2
PMW-2

9
PMW-3

Depth, Ft Description Color
5
Dark Brown organic sandy
saprolite minor mica 5 YR 2/2
10
Dark brown sandy
saprolite, large rounded
pebbles abundant mica
flakes moist to saturated 5 Y 4/4
15
Dark brown sandy
saprolite minor rock
fragments saturated 10 YR 2/2
PMW-3

10

PMW-4

Depth, Ft Description Color
0 -5
Reddish Brown Sandy Soil,
dry 2.5 YR 2/8
10
Orange Brown Coarse
sandy saprolite, dry 10 YR 4/6
15
Dark tan to orange brown
sandy saprolite dry 5 YR 4/4
20
Tan saprolite - sandy clay
very moist to saturated 10 YR 6/6
25
Tan saprolite - sandy clay
very moist to saturated 10 YR 6/6
30
Tan saprolite - sandy clay
very moist to saturated 10 YR 6/6
35
Clayey silt slightly sandy
saprolite - saturated 10 YR 5/4
40
Weathered to partially
weathered rock drier 5 YR 6/4
45
Weathered to partially
weathered rock very moist 10 YR 4/4
50
Weathered to partially
weathered rock saturated 10 YR 4/4
PMW-4

11
Attachment 2 Well Completion Records

WELL CONSTRUCTION RECORD
This form can be used for single o r multiple w ells
1. Well Contractor Information:
JOHNNY BURR
Well Contractor Name
A- 3098
NC Well Contractor Certification Number
GEOLOGIC EXPLORATION, INC
Company Name
2. Well Construction Permit #:
List all appl icab l e well co nstruction pe rmits (i .e. County , state, Va rianc e, etc.)
3. Well Use (check well use):
Water Supply Well:
D Agricultural □Municipal/Public
□Geothermal (Heating/Cooling Supply) □Residential Water Supply (single)
□Industrial/Commercial □Residential Water Supply (shared)
□Irrigation
Non-Water Supply Well:
GJMonitoring □Reco very
Injection Well:
□Aquifer Recharge D Groundwater R emediati on
□ Aquifer Storage and Recovery □ Salinity Barrier
□Aquifer Test □ Stormwater Drainage
□Experimental Technology □ Subsidence Control
□Geothermal (Closed Loop) □Tracer
D Geothermal (Heating/Cooling Return) □Other (explain under #21 Remark s)
4. Date Well(s) Completed: 08/14/19 Well ID # PMW-1
5a. Well Location:
WRENN ROAD WASTE WATER PLANT
Facility /Owner Name Facility ID # (if applicable)
8828 WRENN ROAD GARNER 27529
Physical Address , City , and Zip
WAKE
County Parcel Identification No. (PIN)
5b. Latitude and Longitude in degrees/minutes/seconds or decimal degrees:
(if well field , one lat/long is sufficient )
35° 38' 20.87" 78° 34' 59.72" ____________ N ______________ W
6. Is (are) the well(s): IZlPermanent or □Temporary
7. Is this a repair to an existing well: □Yes or EJNo
If/hi s is a repair, fi ll out known well construction infor mation and explain the nature of the
repair under #2 1 remar ks sectwn or on the back of this f orm .
8. Number of wells constructed: ___ 1 ________ _
For multiple inject,on or non -water s upp ly wells ONLY with the same construction, y ou can
subm it one form .
I For Internal U se ONLY :
14. WAT E R ZONES
FROM TO DES CRIPTION
ft. ft.
ft. ft.
15. OUTER CA SING (f or multi-c ase d wdls ) O R L INER (if a p plicabl e)
FROM TO I DIAMET E R I THICKNE SS I MATERI A L
ft. ft. in .
16. INNER CASING OR TU B ING (11:eotherm al closed-loop )
FROM TO DIAMETER THIC K NES S MATERIAL
0.0 ft. 33.0 ft. 2.0 in . SCH 40 P V C
ft. ft. In.
17 .SCREE N
FROM TO DIAMETE R SLOT SIZE THI CK NE SS MA T E RI AL
33.0 ft. 43.0 ft. 2.0 in. .010 SCH 40 P VC
ft. ft. in.
18.GROUT
FR OM TO MATE RIA L EMPL AC EME NT METH OD &AM OUNT
0.0 ft. 29.0 ft. PO RllAND B B>JTONITE SLURRY
ft. ft.
ft. ft.
19. SAND /GRAV E L P A CK !If aoollc abl e)
FROM TO MATE RIA L EMPLACE ME NT METHOD
31.0 ft. 43.0 ft. 20-40 FINE SILICA SAND
ft. ft.
2 0 . DRILLI N G LOG !att ach additional shtd s If n ece ssarv )
FR OM TO DE SCRIPTION (color , h a rdn e ss, soi Vrock t yp e, izrain size, etc .)
0.0 ft. 1.0 ft. GRAVEL
1.0 ft. 6 .0 ft. O RANGE SANDY CLAY
6.0 ft. 40.0 ft. BROWN SILTY CLAY
40.0 ft. 43.0 ft. BROWN ROCK
ft. ft.
ft. ft.
ft. ft.
21 .REMARKS
BENTONITE SEAL FROM 29.0 TO 31.0 FEET
22. Certification: ~ ./J /VVf-/
09/05/19
Signature of C ertified W e ll Contractor Dat e
By s ig mng this f orm, I hereby certify that the well(s) was (were) const ructed ,n accordan ce
wi th 15A NCAC 02C .0100 or 15A NCAC 02 C .02 CX! Well Construct w n st a ndards and t hat a
copy of this record has bee n prov i ded to the well owner .
23. Site diagram or additional well details:
You ma y use the back of this pa g e t o pr ov ide additio n al w ell s ite detail s or well
construc t ion det ails. You may al so att ach additional pag es if ne cessary .
SUBMITTAL INSTUCTIONS
9. Total well depth below land surface: ____ 4_3_.0 ________ (ft.) 24a. For All Wells: Submit thi s form within 30 days of completi on of w ell
For multiple wells h ot all dep ths if different (examp le -3@200 'and 2@ 100 1 con s truction to the following:
10. Static water level below top of casing: ___ 2_2_._0 _______ (ft.)
If water lev el is abo ve casing , use "+"
11. Borehole diameter: __ 1_0_._0_/6_._0 __ (in.)
12. Well construction method: __ A_U_G_E_R_f_A_I R _______ _
(i.e. auger , rotary , cable , direct push , etc.)
FOR WATER SUPPLY WELLS ONLY:
13a. Yield (gpm) ________ Method of test: _______ _
Divi sion of Water Quality , Information Processing Unit ,
1617 Mail Service Center , Raleigh , NC 27699-1617
24b. For Injection Well s: In additi on t o s ending the fonn to th e address in 24 a
abo ve, a ls o submit a copy of this fonn within 30 day s of comple t ion of w ell
construction to the followin g :
Division of Water Quality , Underground Injection Control Program ,
1636 Mail Service Center , Raleigh , NC 2 7699-1636
24c. For Wat er Supply & Injection Wells: In addition to sendin g t he form t o
the address( es) above , also submit one cop y of this fonn within 30 d ays of
13b. Disinfection type: Amount: completion of w ell construction to th e county h ea lth department of the c ounty L:.::.:.:.:=.:.:.:.:.:=..::::..:::.:.:.:=======-....:.=:.::::.:.:.=========.J where constructed.
Form GW·l North Carolina Department of Environment and N atural Resourc es -Di vision of W ater Quality R ev ised Jan. 2 0 13
WELL CONSTRUCTION RECORD
This form can be used for single or multiple wells
For Internal Use ONLY:
1. Well Contractor Information:
JOHNNY BURR
Well Contractor Name
A - 3098
NC Well Contractor Certification Number
GEOLOGIC EXPLORATION, INC
Company Name
2. Well Construction Permit #:
List all applicable well construction permits (i.e. County, State, variance, etc)
3. Well Use (check well use):
Water Supply Well:
❑ Agricultural ❑Mun icipal/Public
❑Geothermal (Heating/Cooling Supply) ❑Residential Water Supply (single)
❑IndustriallCommercial ❑Residential Water Supply (shared)
Non -Water Supply Well:
❑ Aquifer Recharge
❑ Groundwater Remedi at ion
❑Aquifer Storage and Recovery
❑ Salinity Barrier
❑ Aquifer Test
❑ Stormwater Drainage
❑Experimental Technology
❑Subsidence Control
❑Geothermal(Closed Loop)
[-]Tracer
❑Geothermal (Heating/Cooling Return)
❑Other (explain under #21 I
4. Date Well(s) Completed: 08/14/19 Well ID# PMW-2
5a. Well Location:
WRENN ROAD WASTE WATER PLANT
Facility/Owner Name Facility 1D# (if applicable)
8828 WRENN ROAD GARNER 27529
Physical Address, City, and Zip
WAKE
County Parcel Identification No. (PIN)
5b. Latitude and Longitude in degreesiminutes/seconds or decimal degrees:
(if well field, one latllong is sufficient)
350 38' 20.87" N 780 34' 59.72" W
6. Is (are) the well(s): ©Permanent or ❑Temporary
7. Is this a repair to an existing well: ❑Yes or ONo
Ifthis is a repair, fill out known well construction information and explain the nature ofthe
repair under #21 remarks section or on the back ofthis form.
S. Number of wells constructed: 1
For multiple injection or non -water supply wells ONLY with the sane eonstmcdon, you can
submit one form.
9. Total well depth below land surface: 20.0 W.)
For multiple wells list all depths ifdi ferent (example- 3@,200'and 2@100)
10. Static water level below top of casing: 5.0 W.)
If water level is above casing, use "+"
11. Borehole diameter: 10.0/6.0 (in.)
AUGER/AIR
14. WATER ZONES
FROM
TO
DESCRIPTION
ft.
ft.
ft.
ft.
15. OUTER CASING for multi -cased wells OR LNER if applicable)
FROM
TO
DIAMETER
THIICKNESS
I. MATERIAL
I`
ft.
I in.
16. INNER CASING OR TUBING eother at closed -loop)
FROM
TO
DIAMETER
THICKNESS
MATERIAL
0 0 ft.
10 0 ft.
2.0 in.
SCH 40
PVC
ft.
ft.
in.
17. SCREEN
FROM
TO
DIAMETER
SLOT SIZE
THICKNESS
MATERIAL
10.0 ft.
20 0 ft•
2 0 in.
.010
SCH 40
PVC
ft.
ft.
in.
18. GROUT
FROM
TO
MATERIAL
EMPLACEMENT METHOD & AMOUNT
0 0 rt.
6 0 rt.
��n�oe�TON�
SLURRY
ft.
ft.
ft.
ft.
19. SAND/GRAVEL PACK if applicable)
FROM
TO
MATERIAL
EMPLACEMENT METHOD
8.0 ft.
20.0 it.
20-40
FINE SILICA SAND
ft.
ft.
20. DRILLING LOG attach additional sheets if necessary)
FROM
TO
DESCRIPTION (color, hardness, suiVruck type, grain size, etc.)
0.0 It.
5.0 ft•
BROWN SANDY CLAY/ROCKS
5.0 rt.
9 0 rt•
BROWN PWR
9.0 rt•
20 0 rt•
BROWN ROCK
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
21. REMARKS
BENTONITE SEAL FROM 6.0 TO 8.0 FEET
22. Certification:
09/05/19
Signature of Certified Well Contractor
By signing this form, I hereby certify that the well(s) was (were) constructed in accordance
with 15A NCAC 02C .0100 or 15A NCAC 02C .02X Well Construction Standards and that a
copy ofthis record has been provided to the well owner.
23. Site diagram or additional well details:
You may use the back of this page to provide additional well site details or well
construction details. You may also attach additional pages if necessary.
SUBMITTAL INSTUCTIONS
24a. For All Wells: Submit this form within 30 days of completion of well
construction to the following:
Division of Water Quality, Information Processing Unit,
1617 Mail Service Center, Raleigh, NC 27699-1617
24b. For Iniection Wells: In addition to sending the form to the address in 24a
above, also submit a copy of this form within 30 days of completion of well
12. Well construction method: construction to the following:
(i.e. auger, rotary, cable, direct push, etc.)
Division of Water Quality, Underground Injection Control Program,
FOR WATER SUPPLY WELLS ONLY: 1636 Mail Service Center, Raleigh, NC 27699-1636
13a. Yield (gpm) Method of test: 24c. For Water Supply & Injection Wells: In addition to sending the form to
the address(es) above, also submit one copy of this form within 30 days of
13b. Disinfection type: Amount: completion of well construction to the county health department of the county
where constructed.
Form GW-1 North Carolina Department of Environment and Natural Resources -Division of Water Quality Revised Jan. 2013

WELL CONSTRUCTION RECORD
This form can be used for single or multiple wells
For Internal Use ONLY:
1. Well Contractor Information:
JOHNNY BURR
Well Contractor Name
A - 3098
NC Well Contractor Certification Number
GEOLOGIC EXPLORATION, INC
Company Name
2. Well Construction Permit #:
List all applicable well construction permits (i.e. County, State, variance, etc)
3. Well Use (check well use):
Water Supply Well:
❑ Agricultural ❑Mun icipal/Public
❑Geothermal (Heating/Cooling Supply) ❑Residential Water Supply (single)
❑IndustriallCommercial ❑Residential Water Supply (shared)
Non -Water Supply Well:
❑ Aquifer Recharge
❑ Groundwater Remedi at ion
❑Aquifer Storage and Recovery
❑ Salinity Barrier
❑ Aquifer Test
❑ Stormwater Drainage
❑Experimental Technology
❑Subsidence Control
❑Geothermal(Closed Loop)
[-]Tracer
❑Geothermal (Heating/Cooling Return)
❑Other (explain under #21 I
4. Date Well(s) Completed: 08/27/19 Well ID# PMW-3
5a. Well Location:
WRENN ROAD WASTE WATER PLANT
Facility/Owner Name Facility 1D# (if applicable)
8828 WRENN ROAD GARNER 27529
Physical Address, City, and Zip
WAKE
County Parcel Identification No. (PIN)
5b. Latitude and Longitude in degreesiminutes/seconds or decimal degrees:
(if well field, one latllong is sufficient)
350 38' 20.87" N 780 34' 59.72" W
6. Is (are) the well(s): ©Permanent or ❑Temporary
7. Is this a repair to an existing well: ❑Yes or ONo
Ifthis is a repair, fill out known well construction information and explain the nature ofthe
repair under #21 remarks section or on the back ofthis form.
S. Number of wells constructed: 1
For multiple injection or non -water supply wells ONLY with the sane eonstmcdon, you can
submit one form.
9. Total well depth below land surface: 10'0 W.)
For multiple wells list all depths ifdi ferent (example- 3@,200'and 2@100)
10. Static water level below top of casing: 2.0 W.)
If water level is above casing, use "+"
11. Borehole diameter: 10.0 (in.)
AUGER
14. WATER ZONES
FROM
TO
DESCRIPTION
ft.
ft.
ft.
ft.
15. OUTER CASING for multi -cased wells OR LNER if applicable)
FROM
TO
DIAMETER
THIICKNESS
I. MATERIAL
I`
ft.
I in.
16. INNER CASING OR TUBING eother at closed -loop)
FROM
TO
DIAMETER
THICKNESS
MATERIAL
0 0
ft.
6 0 ft.
2.0 in-
SCH 40
PVC
ft.
ft.
in.
17. SCREEN
FROM
TO
DIAMETER
SLOT SIZE
THICKNESS
MATERIAL
6.0
ft.
16.0 ft•
2.0 in.
.010
SCH 40
PVC
ft.
ft.
in.
18. GROUT
FROM
TO
MATERIAL
EMPLACEMENT METHOD & AMOUNT
0 0
rt.
3 0 rt.
��n�oe�TON�
SLURRY
ft.
ft.
ft.
ft.
19. SAND/GRAVEL PACK if applicable)
FROM
TO
MATERIAL
EMPLACEMENT METHOD
4.0
ft.
16.0 it.
20-40
FINE SILICA SAND
ft.
ft.
20. DRILLING LOG attach additional sheets if necessary)
FROM
TO
DESCRIPTION (color, hardness, suiVruck type, grain size, etc.)
0.0
rt•
10 rt•
BROWNIBLACKTOPSOIL
1.0
rt.
4 0 rt•
BROWNIWHITE SAND
4.0
rt•
16.0 rt•
BROWN ROCK
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
21. REMARKS
BENTONITE SEAL FROM 3.0 TO 4.0 FEET
22. Certification:
09/05/19
Signature of Certified Well Contractor
By signing this form, I hereby certify that the well(s) was (were) constructed in accordance
with 15A NCAC 02C .0100 or 15A NCAC 02C .02X Well Construction Standards and that a
copy ofthis record has been provided to the well owner.
23. Site diagram or additional well details:
You may use the back of this page to provide additional well site details or well
construction details. You may also attach additional pages if necessary.
SUBMITTAL INSTUCTIONS
24a. For All Wells: Submit this form within 30 days of completion of well
construction to the following:
Division of Water Quality, Information Processing Unit,
1617 Mail Service Center, Raleigh, NC 27699-1617
24b. For Iniection Wells: In addition to sending the form to the address in 24a
above, also submit a copy of this form within 30 days of completion of well
12. Well construction method: construction to the following:
(i.e. auger, rotary, cable, direct push, etc.)
Division of Water Quality, Underground Injection Control Program,
FOR WATER SUPPLY WELLS ONLY: 1636 Mail Service Center, Raleigh, NC 27699-1636
13a. Yield (gpm) Method of test: 24c. For Water Supply & Injection Wells: In addition to sending the form to
the address(es) above, also submit one copy of this form within 30 days of
13b. Disinfection type: Amount: completion of well construction to the county health department of the county
where constructed.
Form GW-1 North Carolina Department of Environment and Natural Resources -Division of Water Quality Revised Jan. 2013

WELL CONSTRUCTION RECORD
This form can be used for single or multiple wells
For Internal Use ONLY:
1. Well Contractor Information:
JOHNNY BURR
Well Contractor Name
A - 3098
NC Well Contractor Certification Number
GEOLOGIC EXPLORATION, INC
Company Name
2. Well Construction Permit #:
List all applicable well construction permits (i.e. County, State, variance, etc)
3. Well Use (check well use):
Water Supply Well:
❑ Agricultural ❑Mun icipal/Public
❑Geothermal (Heating/Cooling Supply) ❑Residential Water Supply (single)
❑IndustriallCommercial ❑Residential Water Supply (shared)
Non -Water Supply Well:
❑ Aquifer Recharge
❑ Groundwater Remedi at ion
❑Aquifer Storage and Recovery
❑ Salinity Barrier
❑ Aquifer Test
❑ Stormwater Drainage
❑Experimental Technology
❑Subsidence Control
❑Geothermal(Closed Loop)
[-]Tracer
❑Geothermal (Heating/Cooling Return)
❑Other (explain under #21 I
4. Date Well(s) Completed: 08/14/19 Well ID# PMW-4
5a. Well Location:
WRENN ROAD WASTE WATER PLANT
Facility/Owner Name Facility 1D# (if applicable)
8828 WRENN ROAD GARNER 27529
Physical Address, City, and Zip
WAKE
County Parcel Identification No. (PIN)
5b. Latitude and Longitude in degreesiminutes/seconds or decimal degrees:
(if well field, one latllong is sufficient)
350 38' 20.87" N 780 34' 59.72" W
6. Is (are) the well(s): ©Permanent or ❑Temporary
7. Is this a repair to an existing well: ❑Yes or ONo
Ifthis is a repair, fill out known well construction information and explain the nature ofthe
repair under #21 remarks section or on the back ofthis form.
S. Number of wells constructed: 1
For multiple injection or non -water supply wells ONLY with the sane eonstmcdon, you can
submit one form.
9. Total well depth below land surface: 74.0 W.)
For multiple wells list all depths ifdi ferent (example- 3@,200'and 2@100)
10. Static water level below top of casing: 22.0 W.)
If water level is above casing, use "+"
11. Borehole diameter: 10.0/6.0 (in.)
AUGER/AIR
14. WATER ZONES
FROM
TO
DESCRIPTION
ft.
ft.
ft.
ft.
15. OUTER CASING for multi -cased wells OR LNER if applicable)
FROM
TO
DIAMETER
THIICKNESS
I. MATERIAL
I`
ft.
I in.
16. INNER CASING OR TUBING eother at closed -loop)
FROM
TO
DIAMETER
THICKNESS
MATERIAL
0.0 ft'
64.0 ft•
2.0 in.
SCH 40
PVC
ft.
ft.
in.
17. SCREEN
FROM
TO
DIAMETER
SLOT SIZE
THICKNESS
MATERIAL
64.0 ft.
74 0 ft•
2 0 in.
.010
SCH 40
PVC
ft.
ft.
in.
18. GROUT
FROM
TO
MATERIAL
EMPLACEMENT METHOD & AMOUNT
0 0 rt.
58 0 rt.
��°"oB�To"�
SLURRY
ft.
ft.
ft.
ft.
19. SAND/GRAVEL PACK if applicable)
FROM
TO
MATERIAL
EMPLACEMENT METHOD
61.0 ft.
74.0 it.
20-40
FINE SILICA SAND
ft.
ft.
20. DRILLING LOG attach additional sheets if necessary)
FROM
TO
DESCRIPTION (color, hardness, suiVruck type, grain size, etc.)
0.0 rt•
1 0 rt•
BROWN SAND
1.0 rt.
8 0 rt•
TANIORANGE CLAY
8.0 rt•
62.0 rt•
TANIBROWN SANDY CLAY
62.0 rt•
74.0 rt.
BROWN ROCK
ft.
ft.
ft.
ft.
ft.
ft.
21. REMARKS
BENTONITE SEAL FROM 58.0 TO 61.0 FEET
22. Certification-
09/05/19
Signature of Certified Well Contractor
By signing this form, I hereby certify that the well(s) was (were) constructed in accordance
with 15A NCAC 02C .0100 or 15A NCAC 02C .02X Well Construction Standards and that a
copy ofthis record has been provided to the well owner.
23. Site diagram or additional well details:
You may use the back of this page to provide additional well site details or well
construction details. You may also attach additional pages if necessary.
SUBMITTAL INSTUCTIONS
24a. For All Wells: Submit this form within 30 days of completion of well
construction to the following:
Division of Water Quality, Information Processing Unit,
1617 Mail Service Center, Raleigh, NC 27699-1617
24b. For Iniection Wells: In addition to sending the form to the address in 24a
above, also submit a copy of this form within 30 days of completion of well
12. Well construction method: construction to the following:
(i.e. auger, rotary, cable, direct push, etc.)
Division of Water Quality, Underground Injection Control Program,
FOR WATER SUPPLY WELLS ONLY: 1636 Mail Service Center, Raleigh, NC 27699-1636
13a. Yield (gpm) Method of test: 24c. For Water Supply & Injection Wells: In addition to sending the form to
the address(es) above, also submit one copy of this form within 30 days of
13b. Disinfection type: Amount: completion of well construction to the county health department of the county
where constructed.
Form GW-1 North Carolina Department of Environment and Natural Resources -Division of Water Quality Revised Jan. 2013

15
Attachment 3 Pumping Test Analysis Curves
10. 100. 1000. 1.0E+4
0.1
1.
10.
Time (sec)
Di
s
p
l
a
c
e
m
e
n
t

(
f
t
)
WELL TEST ANALYSIS
Data Set:
Date: 08/27/19 Time: 08:48:48
PROJECT INFORMATION
Company: Eagle Resources
Client: CORPUD
Location: Wrenn road
Test Well: pmw-1
Test Date: 8/25/19
AQUIFER DATA
Saturated Thickness: 21. ft
WELL DATA
Pumping Wells
Well Name X (ft)Y (ft)
PMW-1 0 0
Observation Wells
Well Name X (ft)Y (ft)
PMW-1 0 0
SOLUTION
Aquifer Model: Unconfined Solution Method: Neuman
T = 7.156 ft2/day S = 0.009562
Sy = 0.5 ß = 0.01761
10. 100. 1000. 1.0E+4
0.1
1.
10.
Time (sec)
Di
s
p
l
a
c
e
m
e
n
t

(
f
t
)
WELL TEST ANALYSIS
Data Set:
Date: 08/27/19 Time: 09:21:45
PROJECT INFORMATION
Company: Eagle Resources
Client: CORPUD
Location: Wrenn road
Test Well: pmw-2
Test Date: 8/26/19
AQUIFER DATA
Saturated Thickness: 15. ft
WELL DATA
Pumping Wells
Well Name X (ft)Y (ft)
PMW-2 0 0
Observation Wells
Well Name X (ft)Y (ft)
PMW-2 0 0
SOLUTION
Aquifer Model: Unconfined Solution Method: Neuman
T = 130.9 ft2/day S = 0.003477
Sy = 0.006212 ß = 0.0003113
10. 100. 1000. 1.0E+4
1.
10.
100.
Time (sec)
Di
s
p
l
a
c
e
m
e
n
t

(
f
t
)
WELL TEST ANALYSIS
Data Set:
Date: 08/27/19 Time: 10:03:50
PROJECT INFORMATION
Company: Eagle Resources
Client: CORPUD
Location: Wrenn road
Test Well: pmw-4
Test Date: 8/26/19
AQUIFER DATA
Saturated Thickness: 50. ft
WELL DATA
Pumping Wells
Well Name X (ft)Y (ft)
PMW-4 0 0
Observation Wells
Well Name X (ft)Y (ft)
PMW-4 0 0
SOLUTION
Aquifer Model: Unconfined Solution Method: Neuman
T = 1.071 ft2/day S = 0.01199
Sy = 0.5 ß = 0.0001824

| DRAFT Interim Groundwater Monitoring Results Memorandum
Appendix 4 Complete Groundwater Monitoring Results
555 Fayetteville Street Suite 900 Raleigh , NC 27601 -3034
(919) 232 -6600

Appendix 4 Complete Groundwater Monitoring
Results
R. Tart D. Godfrey R. Tart D. Godfrey
11/21/2019 11/21/2019 11/21/2019 11/21/2019
11:18 AM 8:40 AM 12:23 PM 12:10 PM
Clear/Cool/Sunny
24 8 6 21.9
43 20 16 74
9.31 6 4.57 25.5
0.48 1.86 1.58 5.08
5.75 5.3 6.03 5.97
16.6 16.8 16.9 17.6
98.9 69.6 129.8 126.2
<60 <60 199 172
90 <50 <50 134
<10 <10 <10 <10

| DRAFT Interim Groundwater Monitoring Results Memorandum
Appendix 4 Complete Groundwater Monitoring Results
555 Fayetteville Street Suite 900 Raleigh , NC 27601 -3034
(919) 232 -6600

R. Tart R. Tart R. Tart D. Godfrey
1/17/2020 1/17/2020 1/17/2020 1/17/2020
10:05 AM 10:49 AM 8 :18 AM 10:40 AM
Partly Sunny, Cool
23.8 7.4 5.6 20.5
43 20 16 74
9.4 6.1 6.5 27
0.98 0.48 1.06 2.04
5.87 6.02 6.68 6.07
14 15.1 12.8 15.3
91.6 67.2 110.1 121.2
<60 <60 <60 68
74 <50 <50 <50
<10 <10 <10 <10

| DRAFT Interim Groundwater Monitoring Results Memorandum
Appendix 4 Complete Groundwater Monitoring Results
555 Fayetteville Street Suite 900 Raleigh , NC 27601 -3034
(919) 232 -6600

D. Godfrey R. Tart R. Tart D. Godfrey
3/12/2020 3/12/2020 3/12/2020 3/12/2020
12:06 PM 7 :50 AM 12:30 PM 9:59 AM
Cloudy, Cool
20.85 7.5 5.3 16.2
43 20 16 74
11 7 5.25 28.5
1.31 0.53 3.49 1.76
5.31 5.93 7.03 6.16
18.2 14.6 14.3 16.8
90.9 71.8 62.2 115.4
<60 <60 141 <60
64 <50 <50 88
<10 <10 <10 <10

| DRAFT Interim Groundwater Monitoring Results Memorandum
Appendix 4 Complete Groundwater Monitoring Results
555 Fayetteville Street Suite 900 Raleigh , NC 27601 -3034
(919) 232 -6600

D. Godfrey R. Tart R. Tart R. Tart
4/14/2020 4/14/2020 4/14/2020 4/14/2020
10:15 AM 8 :30 AM 11:45 AM 10:28 AM

20.9 7.7 5.7 16.4
43 20 16 74
10.8 6.5 5.0 28.25
0.39 0.23 0.46 1.61
7.15 7.32 6.27 6.05
17.6 14.8 15.5 17
92.2 68.8 116.4 110.8
<60 <60 <60 <60
70 <50 <50 96
<10 <10 <10 <10

| DRAFT Interim Groundwater Monitoring Results Memorandum
Appendix 4 Complete Groundwater Monitoring Results
555 Fayetteville Street Suite 900 Raleigh , NC 27601 -3034
(919) 232 -6600

R. Tart R. Tart R. Tart R. Tart R. Tart
8/20/2020 8/20/2020 8/20/2020 8/20/2020 8/20/2020
1:25 PM 1:25 PM 12:01 PM 3 :15 PM 12:45 PM

22.8 22.8 9.8 6 19
43 43 20 30 74
9.8 9.8 5.1 5 26
0.68 0.68 1.46 1.69 1.5
5.93 5.93 6.01 6.63 6.81
19.1 19.1 20.7 19.8 19
94.5 96.7 73.3 43.5 124.5
<60 <60 <60 482 69
88 90 <50 <50 123
<10 <10 <10 <10 <10

| DRAFT Interim Groundwater Monitoring Results Memorandum
Appendix 4 Complete Groundwater Monitoring Results
555 Fayetteville Street Suite 900 Raleigh , NC 27601 -3034
(919) 232 -6600

D. Godfrey D. Godfrey D. Godfrey D. Godfrey D. Godfrey/
E. Batchelor
11/4/2020 11/4/2020 11/4/2020 11/4/2020 11/4/2020
8:25 AM 8:25 AM 9:08 AM 10:44 AM 12:00 PM

22.3 22.3 7.8 5.7 18.9
43 43 20 16 74
10.25 10.25 6 5.25 27
1.12 1.12 1.86 0.44 0.72
5.32 5.32 5.08 5.65 5.87
17 17 18.5 18.1 18.2
82 82.4 73.6 101.5 129.8
<60 <60 72 73 <60
59 61 <50 <50 88
<10 <10 <10 <10 <10

| DRAFT Interim Groundwater Monitoring Results Memorandum
Appendix 4 Complete Groundwater Monitoring Results
555 Fayetteville Street Suite 900 Raleigh , NC 27601 -3034
(919) 232 -6600

D. Godfrey D. Godfrey D. Godfrey D. Godfrey D. Godfrey
3/10/2021 3/10/2021 3/10/2021 3/10/2021 3/10/2021
8:50 AM 8:50 AM 9:22 AM 11:16 AM 1:00 PM
Sunny - 6
18.3 18.3 6.9 5.9 14.1
43 43 20 16 74
12.25 12.25 6 .5 5 30
3.5 2 3.5 2 1.52 2.83 0.72
5.6 2 5.6 2 5.75 6.48 5.8 5
16.5 16.5 15 .5 14.2 19.8
8 4.5 8 3.0 7 9.3 85.2 123.9
97 132 199 601 <5 0
71 7 1 16 176 71
<5 <5 <5 <5 <5

555 Fayetteville Street
Suite 900
Raleigh , NC 27601 -3034
(919) 232 -6600
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