20190752 Ver 6_401 Monitoring Plan Addendum - 2022-09-08_20220908

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Project Name: Chemours — Fayetteville Works — Barrier Wall Project
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Attached please find the revised and updated "Monitoring Plan" in response to your request in review of the
401 permit modification for the Chemours Fayetteville Works Barrier Wall Project.
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Geosyntec °
consultants
Geosyntec Consultants of NC. P.C.
NC License No.: C-3500 and C-295
Date:
To:
From:
Subject:
Memorandum
September 8, 2022
The Chemours Company, FC, LLC
Geosyntec Consultants of NC, P.C.
Wetland Monitoring Plan: Addendum
Chemours Fayetteville Works Project
Bladen/Cumberland County, North Carolina
DWR # 20190752v6; USACE Aid # SAW-2019-00296
2501 Blue Ridge Road, Suite 430
Raleigh, NC 27607
PH 919.870.0576
FAX [phone]
www.geosyntec.com
INTRODUCTION
This Wetland Monitoring Plan Addendum ("Addendum") has been prepared by Geosyntec
Consultants of NC, P.C. (Geosyntec) for The Chemours Company FC, LLC (Chemours). On
August 13, 2021 the Wetland Monitoring Plan ("Monitoring Plan") was submitted to the North
Carolina Department of Environmental Quality (NCDEQ) along with a Section 404 permit
modification request (SAW-2019-00296) through the United States Corps of Engineers (USACE).
This addendum to the previously submitted plan is based on comments by the North Carolina
Department of Environmental Quality (NCDEQ) via email on August 25, 2022.
This document first presents a summary of the stream and wetland monitoring scope described in
both the Monitoring Plan and this Addendum, and then presents the Addendum monitoring scope
additions based on comments and recommendations received from NCDEQ.
SUMMARY OF MONITORING SCOPE
The table on the following page summarizes the monitoring scopes to be implemented based on
both the Monitoring Plan and this Addendum.
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Wetland Monitoring Plan: Addendum
September 8, 2022
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Table 1 Summary of Monitoring Scope
Geosyntec °
consultants
Geosyntec Gmsulla nle of NC, P.C.
NC F.ioense Nu.: G35tl9 and C-2.95
Scope / Item
Described in
Document
Duration and Frequency
Location
Performance
Standards
Groundwater
Gauges
USACE
Datapoints
NCWAM Forms
DWR Stream
Form
Wetland
Delineation
Reports
Monitoring Plan
and Addendum
Addendum
Monitoring Plan
and Addendum
Addendum
Addendum
Annual, 5 years
Continuous, 5 years
Annual, 5 years
Annual, 5 years
Semi-annual (early and late
growing season), 5 years
Monitoring Plan
Pre -construction: 2020
Post Construction: 2027
Addendum
Annual, 5 years
Wetland Study Area
Wetlands 2, 3, 4, and 6
Wetland and Upland
(Figure 1)
Central Area of Each
Wetland
Stream reaches above and
below barrier wall
Wetland Study Area
N/A
Notes:
USACE: United States Army Corps of Engineers
DWR: North Carolina Department of Environmental Quality, Division of Water Resources
NCWAM: North Carolina Wetland Assessment Method
MONITORING PLAN ADDENDUM
This section presents first comments received from NCDEQ on August 25, 2022 in italicized text
followed by responses in plain text. Responses are provided for comments numbered 5.a.i through
5.d.i in the DEQ comment letter. These responses describe additions and modifications to the
monitoring scope and serve as an addendum supplement to the existing Monitoring Plan. Wetlands
referenced in this addendum are described in Section 3.1.1. of the Waters of the US Findings
Report and detailed in Figure 1(a-c).
5a.i "Please sped the `additional information' that will be gathered as part of the baseline
characterization. Specifically what data will be collected and how will it be collected? In
Section 3.1.1. of the Waters of the US Findings Report seven distinct wetland areas were identified
based on initial observations. Please expand the baseline assessment for the seven wetland areas
to include characterization of landscape, soils, vegetation, and hydrology. The Division
recommends NC Wetland Assessment Methodology (NCWAM) forms completed for each of the
seven wetland areas identified to document baseline conditions of these wetland systems. Ideally,
a licensed soil scientist should conduct the soils assessments."
Geosyntec will collect NCWAM forms within the center of each of the seven wetlands during
2022 data collection field effort, prior to barrier wall construction. Additionally, NCWAM forms
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NC F.ioense Nu.: G35tl9 and C-2.95
will be completed at the same locations for each subsequent year of the monitoring period.
NCWAM forms will be completed by an experienced biologist who has completed Wetland
Delineation training for USACE methodology, including soil identification and characterization.
Additionally, a licensed soil scientist will conduct the soils assessments during the baseline
characterization effort planned for September 2022.
5a. ii "The initial wetland determination sample points focus on wetland/upland edges which is
appropriate for a delineation effort. However, the Division believes that plan should focus on
systemwide functional monitoring of the resources. Therefore, please add additional data
collection points in the central areas of wetlands W2, W3, and W6."
In an effort to better characterize the wetland form and function as a whole, and not just along the
delineated boundaries, Geosyntec established nine additional data points during a 2021
preliminary baseline assessment within the central areas of the wetlands. Data points appended
with a "U" (upgradient of the original datapoint) or "D" (downgradient of the original data
point) are additional datapoints sampled in 2021 to supplement the original data points (Table
2). The locations of the original and additional data points are provided in Figure 1 of the
addendum. These additional data points already established by Geosyntec are consistent with
NCDEQs' request for additional data points.
Table 2 Wetlands and Associated Datapoints
Wetland
Type
Data Points
Additional Data Points
Wetland 1 (WI)
Wetland 2 (W2)
Wetland 3 (W3)
Wetland 4 (W4)
Wetland 6 (W6)
Wetland 6 (W6)
Wetland 7 (W7)
PFO
PFO
PFO
PFO
PEM
PFO
PFO
1, 2
3, 4
5, 6
7, 8
9, 10
11, 12
14
1U
3U
5U, 5U2, 5U3
N/A
N/A
9U, 11D
13D, 13, 13U
5a. iii "At least 4 representative baseline groundwater gauges should be installed before
construction to document pre -construction data such as the existing hydroperiod and be used in
postconstruction monitoring."
At the request of NCDEQ five transects with representative baseline groundwater gauges will be
installed within wetlands 2, 3, 4, and 6. Five pairs of upland/wetland gauges will be installed in
the wetlands and adjacent upland areas along a transect perpendicular to the wetland boundary
(Figure 2); and remain in place throughout the course of the monitoring period. The gauges will
be installed to a minimum depth of 15 inches below surface using USACE technical specifications
outlined in the June 2005 Technical Standard for Water -Table Monitoring of Potential Wetland
Sites, ERDC TN-WRAP-05-2. The gauges are anticipated to be installed during mid -
September 2022 prior to barrier wall installation to establish baseline conditions.
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NC F.ioense Nu.: G35tl9 and C-2.95
5a.iv "For any stream segments left as `non -impacted' on the western side of the proposed wall,
please propose a baseline assessment. The Division recommends conducting DWR Stream Forms
assessments pursuant to the North Carolina Methodology for Identification of Intermittent and
Perennial Streams and their Origins, Version 4.11 for all stream proposed to be `nonimpacted. "'
Geosyntec will conduct baseline assessment west of the barrier wall for the four non -impacted
areas of the streams above the barrier wall using the DWR stream form identified by NCDEQ.
These forms will be completed by an experienced biologist or one who has completed the NC
Surface Water Identification Training Certificate program. Geosyntec will resurvey the streams
west (non -impacted) and east (impacted) of the barrier wall semi-annually to occur in the early
growing season and the late growing season. An emphasis of the detailed documentation of
monitored streams' biology (macrobenthics and other biological indicators) will be incorporated
into the development of the forms.
5b. i "Given the permanent drawdown expected from the proposed barrier wall and the connection
between several of the wetlands' primary hydrology to the hillside/upstream seeps, the Division is
concerned that visual observation monitoring is not sufficient to demonstrate a 'no impact'
determination. Therefore, the Division recommends direct hydrologic measurement using multiple
groundwater gauges over a multiyear monitoring period. Groundwater gauges should be installed
per US Army Corps of Engineers (USACE) technical specifications guidance."
As described in response to comment 5a.iii., multiple groundwater gauges will be installed prior
to the construction activities to provide baseline data. These data will be monitored continuously
during the five year monitoring period. These data will offer further understanding of the influence
of the remedy construction on recorded groundwater levels within the wetland study area. This
will also allow specific measurement of hydrological changes of the ground water table in the
wetlands.
5b.ii "The monitoring plan's performance standards need to be more specific and measurable.
For example, groundwater gauges should meet a minimum 5% hydroperiod during the growing
season each year under normal rainfall conditions. Please update the plan to include
specific/measurable performance standards. The growing season start/end dates (and source of
this information) should be specified in the monitoring plan. In addition, the distance from the site
to the rainfall data sources should be provided if there is no on -site rain gauge."
To assess groundwater levels within the wetlands groundwater gauges will be monitored
throughout the requested 5-year monitoring period post -construction. Each gauge will log
groundwater elevation throughout the length of the study.
A performance monitoring line of evidence for wetland conditions will be groundwater gauge data
meeting a minimum of 5% hydroperiod (12.15 days) each year during the growing season
indicated by groundwater within 12 inches (") of soil surface to meet the primary hydrology
indicator for high water table. The growing season is 16 March to 14 November (243 days) based
on the Natural Resource Conservation Service (NRCS) Bladen County Soil Survey, for each year
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Wetland Monitoring Plan: Addendum
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under normal rainfall conditions (a review of NRCS WETS table growing season data did not yield
any available data for Bladen or Cumberland Counties). Normal rainfall conditions are determined
to occur when rainfall values for a typical year. Typical year conditions will generally be
determined by: Normal precipitation conditions based on the three 30-day periods preceding the
observation date. For each period, a weighted condition value is assigned by determining whether
the 30-day precipitation total falls within, above, or below the 70th and 30th percentiles for totals
from the same date range over the preceding 30 years. A determination of "normal," "wetter than
normal," or "drier than normal" is made based on the condition value sum. The USACE's
Antecedent Precipitation Tool will be consulted to assess typical year precipitation totals.
Additional reference rainfall data will be assessed from the Fayetteville Area (PWC) monitoring
station, located approximately 15 miles north of the Site. This station is the closest station to the
Site which includes historical average month -to -date and year-to-date data to use as a reference
for "normal" conditions. Rainfall data may also be augmented using data from Chemours' Onsite
meteorological data station which records data on five minute intervals and the United States
Geological Survey (USGS) W.O. Huske Dam precipitation gauge (station 02105500) which
records rainfall data on 15 minute intervals. The Onsite met station is approximately one mile
away from the wetlands and the USGS station is between 100 yards and one mile away from the
wetlands.
5b. iii "In addition to groundwater monitoring, the Division believes that an annual assessment of
vegetation composition and health is important. The proposed monitoring plan does ident0; good
examples of negative wetland plant stressors (lack of growth/vigor, mortality, upland/pioneer
plant competition). However, the monitoring plan proposes use of USACE wetland data forms as
the assessment tool for identification of the vegetation stressors. These forms were developed as a
delineation tool and not a monitoring/functional assessment tool. Therefore, please expand the
proposed data collection to include information such as tree/shrub species, height, DBH, health,
and wetland indicator status to assess changes in wetland community diversity, density and health.
The Division recommends using NCWAM forms. "
While use of the USACE methodology can provide adequate data on vegetative conditions by
detailing species composition, dominance, indicator status, etc.; Geosyntec agrees with NCDEQ
that additional data using NCWAM forms will provide even more detail on vegetative community
species composition and condition/health and will supplement the monitoring plan well.
Geosyntec will utilize NCWAM forms within each of the seven wetlands. Each form will be
completed annually for a five year period at the same location within each wetland.
5c. i "To assess potential secondary impacts to surface waters, the Division believes that semi-
annual assessments of surface hydrology indicators is necessary. Please update the monitoring
plan to include conducting DWR Stream Form assessments pursuant to the North Carolina
Methodology for Identification of Intermittent and Perennial Streams and their Origins, Version
4.11 for all stream segments on a semi-annual basis."
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DWR Stream Form assessments will be conducted for each stream (Figure 1) by an experienced
biologist or one who has completed the Surface Water Identification Training Certification course.
The form will be completed at the same location semi-annually (early growing season and late
growing season) to monitor for potential changes in surface hydrology and the effects on the
biological community.
Sd. i "The Division believes that three years will likely not be a sufficient length of time to visually
assess the extent of stream and wetland function degradation or loss. Therefore, please update the
plan to include five years of monitoring for all elements. After five years, the groundwater data,
surface hydrology indicators and vegetation composition/health should collectively provide
evidence ofwhether the barrier wall is having an impact on adjacent wetlands and surface waters.
This information along with a site re -delineation should allow proper assessment ofwhether state
wetland and surface water resources have been lost or significantly degraded thereby potentially
requiring mitigation."
At the request of NCDEQ, the monitoring period will be extended from three years to five years
post -construction, while also including the additional monitoring protocol adjustments detailed
above. Reports will be submitted annually to NCDEQ by January 31' of the following year.
Encl.
Tables Table 1: Summary of Monitoring Scope
Table 2: Wetlands and Associated Datapoints
Figures Figure la-c: Wetland Monitoring Point Locations
Wetland Monitoring Plan: Addendum DWR # 20190752v6; USACE Aid # SAW-2019-00296
engineers I scientists I innovators

Figures

Legend
▪ 2020 Upland Datapoint
O 2021 Additional Wetland Datapoint
• 2020 Wetland Datapoint
OStream Monitoring Datapoint
Delineated Feature:
i,
111111
Ordinary High Water Mark (OHWM)
Palustrine Emergent (herbaceous) Wetland (PEM)
Palustrine Forested Wetland (PFO)
Wetlands Investigation Area
Exclusion Areas
Groundwater Guage Transect
Notes:
1. The outline of Cape Fear River is a roximate and is based on open data from ArcGIS Online and North Carolina Department of
Environmental Quality Online GIS ajorHydro shapefile).
2. Basemap sources: NC OneMap (2 19). North Carolina Department of Information Technology, Government Data Analytics Center, Center
for Geographic Information and Analysis. Available at https://vvww.nconemap.gov.
250125 0
250 Feet
Wetland Monitoring Point Locations
Wetland Monitoring Report - 2021
Chemours Fayetteville Works
Cumberland/Bladen County, North Carolina
Geosyntec r.
consultants
Geosyntec ConsulLants al NC, P.C.
NC License No.: C-3500 and C-295
Figure
Raleigh
September 2022
1
Projection. NAD 1983 StatePlane South Carolina FIPS 3900 Feet, Units in Foot US

Legend
▪ 2020 Upland Datapoint
O 2021 Additional Wetland Datapoint
• 2020 Wetland Datapoint
OStream Monitoring Datapoint
Delineated Feature:
i,
111111
Ordinary High Water Mark (OHWM)
Palustrine Emergent (herbaceous) Wetland (PEM)
Palustrine Forested Wetland (PFO)
Wetlands Investigation Area
Exclusion Areas
Groundwater Guage Transect
Notes:
1. The outline of Cape Fear River is a roximate and is based on open data from ArcGIS Online and North Carolina Department of
Environmental Quality Online GIS ajorHydro shapefile).
2. Basemap sources: NC OneMap (2 19). North Carolina Department of Information Technology, Government Data Analytics Center, Center
for Geographic Information and Analysis. Available at https://vvww.nconemap.gov.
250
125
0
250 Feet
Wetland Monitoring Point Locations
Wetland Monitoring Report - 2021
Chemours Fayetteville Works
Cumberland/Bladen County, North Carolina
Geosyntec r.
consultants
Geosyntec ConsulLants al NC, P.C.
NC License No.: C-3500 and C-295
Figure
Raleigh
September 2022
la
Projection. NAD 1983 StatePlane South Carolina FIPS 3900 Feet, Units in Foot US

DP9 DP10
%o ❑
AS5-TRI BU; AR�I ES
Legend
❑ 2020 Upland Datapoint
O 2021 Additional Wetland Datapoint
• 2020 Wetland Datapoint
OStream Monitoring Datapoint
Delineated Feature:
i,
111111
Ordinary High Water Mark (OHWM)
Palustrine Emergent (herbaceous) Wetland (PEM)
Palustrine Forested Wetland (PFO)
Wetlands Investigation Area
Exclusion Areas
Groundwater Guage Transect
Notes:
1. The outline of Cape Fear River is a roximate and is based on open data from ArcGIS Online and North Carolina Department of
Environmental Quality Online GIS ajorHydro shapefile).
2. Basemap sources: NC OneMap (2 19). North Carolina Department of Information Technology, Government Data Analytics Center, Center
for Geographic Information and Analysis. Available at https://vvww.nconemap.gov.
250
125
0
250 Feet
Wetland Monitoring Point Locations
Wetland Monitoring Report - 2021
Chemours Fayetteville Works
Cumberland/Bladen County, North Carolina
Geosyntec r.
consultants
Geosyntec ConsulLants al NC, P.C.
NC License No.: C-3500 and C-295
Figure
Raleigh
September 2022
1b
Projection. NAD 1983 StatePlane South Carolina FIPS 3900 Feet, Units in Foot US

Legend
▪ 2020 Upland Datapoint
O 2021 Additional Wetland Datapoint
• 2020 Wetland Datapoint
OStream Monitoring Datapoint
Delineated Feature:
i,
111111
Ordinary High Water Mark (OHWM)
Palustrine Emergent (herbaceous) Wetland (PEM)
Palustrine Forested Wetland (PFO)
Wetlands Investigation Area
Exclusion Areas
Groundwater Guage Transect
Notes:
1. The outline of Cape Fear River is a roximate and is based on open data from ArcGIS Online and North Carolina Department of
Environmental Quality Online GIS ajorHydro shapefile).
2. Basemap sources: NC OneMap (2 19). North Carolina Department of Information Technology, Government Data Analytics Center, Center
for Geographic Information and Analysis. Available at https://vvww.nconemap.gov.
250
125
0
250 Feet
Wetland Monitoring Point Locations
Wetland Monitoring Report - 2021
Chemours Fayetteville Works
Cumberland/Bladen County, North Carolina
Geosyntec r.
consultants
Geosyntec ConsulLants al NC, P.C.
NC License No.: C-3500 and C-295
Figure
Projection. NAD 1983 StatePlane South Carolina FIPS 3900 Feet, Units in Foot US
Raleigh
September 2022
1c