DEQ-CFW_00061086

DUPONT FAYETTEVILLE WORKS
EXISTING OUTFALL 002 EFFLUENT CHANNEL
VISUAL ASSESSMENT PROTOCOL
REVISON: 1
Final Revision made by
Kyle A. Smith
DuPont Construction Engineer
DuPont Fayetteville Works
22828 NC HWY 87W
Fayetteville, NC 28306
Office 910-678-1593
January 7, 2011
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EXECUTIVE SUMMARY
The intent of the Existing Outfall 002 Effluent Channel Visual Assessment Protocol is to
communicate the DuPont data collection initiative to the North Carolina Department of
Environment and Natural Resources (NCDENR) in a good -faith effort to ensure our
corporate compliance with existing environmental regulations.
DuPont is engaged in a multi -million dollar initiative to redirect site effluent flow via
underground high -density polyethylene (HDPE) pipe and reinforced concrete pipe (RCP)
to eliminate the threat of accelerated erosion resulting in sedimentation build-up in the
Cape Fear River, while simultaneously redirecting approximately 250 acres of storm
water flow from the existing effluent channel. Upon completion of this outfalls relocation
project, DuPont seeks to ascertain stabilization trends in the abandoned effluent channel
using the enclosed survey protocol.
The proposed survey plan is a derivative of the USDA Stream Visual Assessment
Protocol. It offers the following benefits:
• Has precedence of utilization by such organizations as Rutgers University and
the Omni Corporation in assessing stream and stream -like conditions in the state
of New Jersey.
• Establishes numeric values by which data -trends can be derived.
• Uses a number of stabilization elements by which to assess the reclamation
process, including: Hydrologic Alteration, Bank Stability, Vegetation, Water
Appearance, and Channel Condition.
• The assessment will be used with standardized reach lengths of 660 ft, based
upon the average active channel width from our initial survey.
• GPS will be utilized to control survey location variables.
• The survey will be re -conducted annually to establish a trend over time.
Upon acceptance of this proposal, DuPont will share the future survey results with
NCDENR and, in consultation with this state entity, establish that environmental
compliance has been met and sustained under state and federal law.
Outfall Assessment Protocol —Rev 1.doc
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BACKGROUND
The DuPont Fayetteville Works plant site is located south of the City of Fayetteville off
NC Highway 87 and is comprised of approximately 2,500 acres of land along the Cape
Fear River. The plant site is located in both Cumberland and Bladen counties in North
Carolina. Approximately 400 acres of the site is situated in Cumberland County and the
remaining 2,100 acres are in Bladen County. Currently only about 300 acres (12%) of
this large tract of land has been developed for industrial use with the bulk of the property
remains as undeveloped wooded and open grassed fields.
The plant extracts water from the Cape Fear River for use as both process water and
non -contact process cooling. Treated process wastewater and non -contact cooling
water are conveyed along with stormwater run-off to a wood -lined ditch outfall structure
at the south end of the developed site designated as Outfall #002 in the NPDES Permit
NC0003573. Currently, the flow from the permitted outfall discharges to an effluent
channel that extends through a wooded section of the property, approximately 6,000 feet
to the Cape Fear River. The flow enters the river downstream of Lock and Dam #3. The
erosive conditions in the effluent channel have caused sediment to be deposited in the
Cape Fear River. A project was established to address this situation and the current
flow will be redirected to a new effluent discharge system that eliminates the risk of both
future soil erosion and sedimentation collection at the point of discharge into the Cape
Fear River.
APPROACH
Due to the erosive nature of the flow the condition of the existing effluent channel has
been deteriorating for some years, DuPont is initiating a data collection effort. Once the
flow has been removed from this effluent channel, DuPont's intent is to observe the rate
at which the natural vegetative process, storm water runoff, and other naturally erosive
elements stabilize the soils and smoothes the angle of soil repose. DuPont will monitor
the progress of the reclamation via the attached condition assessment procedure. The
basis for this procedure is a document prepared by the United States Department of
Agriculture (USDA) titled Stream Visual Assessment Protocol. Although the existing
effluent channel is not technically defined as a stream, this protocol can be used as a
basis for the assessment in a modified format. Modifications include: removal of those
assessment elements that are not applicable to this effluent channel and the addition of
"vegetation" as an assessment element. This protocol provides scores, based upon the
assessment elements that will be used as a comparative basis to evaluate whether the
channel condition is improving or degrading. Precedence for modifying this protocol
already exists, as evidenced by a derivative of the USDA model that was developed by
Rutgers University and Omni Environmental Corporation.
The assessment procedure is outlined on the following pages. In summary, the effluent
channel will be assessed immediately before and after the flow has been redirected,
then assessed again one-year after the flow has been redirected. The assessments will
be conducted in late spring, per the protocol schedule below, and by the same DuPont
personnel. Once the one-year assessment is completed, the results will be evaluated by
DuPont, in consultation with the NCDENR, and recommendations shall be prepared as
to whether or not continued monitoring is warranted, based upon stabilization trends.
Outfall Assessment Protocol —Rev 1.doc
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PROTOCOL SCHEDULE
Current condition
• Perform a walking survey in late spring before flow has been redirected.
• Establish reach (defined below) sections
o Identify on sketches
o Locate with handheld GPS
• Take photographs at same locations as initial walking survey dated 11/23/2010
o Take additional photos between beginning and end of each reach
o Identify locations by using handheld GPS
• Estimate depth of current flow and record/mark — with/on photos
• Compare photos at same locations
Redirected flow
• Perform a condition assessment in late spring after flow has been rerouted.
o Use the modified version titled "Visual Assessment Protocol' (below)
based on the United States Department of Agriculture — USDA as a basis.
■ Establishes a numerical value (score) of the environmental
conditions
• Take photographs at same location as Current Condition walking survey
o Identify locations by using handheld GPS
o Take additional photographs to record condition of bottom of channel.
• Estimate depth of current flow, if any, and record/mark — with/on photos
• Compare photos at same locations
Redirected flow plus 1-year
• Perform a condition assessment in late spring.
o Use the modified version titled "Visual Assessment Protocol' (below)
based on the United States Department of Agriculture — USDA as a basis.
• Take photographs at same location as pre -project walking survey
o Identify locations by using handheld GPS
o Include photographs of bottom of channel at same location as redirected
flow photographs
• Estimate depth of current flow, if any, and record/mark — with/on photos
• Note any changes
o Vegetation growth
o Vegetation deterioration — trees uprooted
o Additional erosion/undercutting
o Bank collapses/failures
• Compare redirected flow and redirected flow plus 1-year numerical values and
photos and determine the stabilization trend.
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SAFETY
All assessment work shall be done in accordance with Federal, State, and local
regulations, including DuPont Safety Standards. Discuss the assessment procedure
and intent with the Fayetteville site Safety Coordinator before commencing any
assessment work.
VISUAL ASSESSMENT PROTOCAL
This assessment protocol provides a basic level of channel health evaluation. This
protocol provides an assessment based primarily on physical conditions within the
assessment area. It may not detect some resource problems caused by factors located
beyond the area being assessed.
The DuPont survey team will assess one or more representative reaches. A reach is a
length of stream. For this protocol, the length of the assessment reach is 12 times the
active channel width. For the sake of clarity and consistency in defining the active
channel width, we have averaged the width of 22 points along the effluent channel from
our preliminary survey data to reach an approximate average of 55 ft. Using this average
as a consistent active channel quantity yields a reach length of 660 ft. The reach should
be representative of the stream through that area. If conditions change dramatically
along the stream, the survey team will identify additional assessment reaches and
conduct separate assessments for each.
Using this protocol
The assessment is recorded on a two -page worksheet. A completed worksheet is
shown in at the end of this document. The visual assessment protocol worksheet
consists of two principal sections: reach identification, and assessment. The
identification section records basic information about the reach, such as name, location,
and land uses. Space is provided for a diagram of the reach, which may be useful to
locate the reach or illustrate problem areas. On this diagram draw all tributaries,
drainage ditches, and irrigation ditches; note springs and ponds that drain to the
channel; include road crossings and note whether they are fords, culverts, or bridges;
note the direction of flow; and draw in any large woody debris, pools, and riffles.
The assessment section is used to record the scores for up to 5 assessment elements.
Not all assessment elements will be applicable or useful given this was an effluent
channel that will no longer host water discharge beyond natural sheet flow from
precipitation. The DuPont survey team will not score elements that are not applicable to
the reclamation process. Per the Visual Assessment Protocol, the survey team will
score an element by comparing their observations to the descriptions provided. The
overall assessment score is determined by adding the values for each element and
dividing by the number of elements assessed. For example, if your scores add up to 32
and you used 5 assessment elements you would have an overall assessment value of
6.4, which is classified as fair. This value provides a numerical assessment of the
environmental condition of the stream reach. This value can be used as a general
statement about the "state of the environment" of the stream or (Over time, the
accumulated data will enable the survey team to establish a reclamation trend that will
provide a general time -frame for a naturally occurring restoration. This estimated
duration will serve as a foundation for future intervention considerations.)
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Reach Description
Active channel width can be difficult to determine. However, active channel width helps
to characterize the stream. For this protocol the survey team will not need to measure
active channel width accurately — a visual estimate of the average width is adequate.
Active channel width is the stream width at the bankfull discharge. Bankfull discharge is
the flow rate that forms and controls the shape and size of the active channel. It is
approximately the flow rate at which the channel begins to move onto its flood plain if the
stream has an active flood plain. The bankfull discharge is expected to occur every 1.5
years on average. Figure 1 illustrates the relationship between baseflow, bankfull flow,
and the flood plain.
Active channel width is best determined by locating the first flat depositional surface
occurring above the bed of the stream (i.e., an active flood plain). The lowest elevation
at which the bankfull surface could occur is at the top of the point bars or other sediment
deposits in the channel bed. Other indicators of the bankfull surface include a break in
slope on the bank, vegetation change, substrate, and debris.
Figure 1 Baseflow, bankfull, and flood plain locations (Rosgen 1996)
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Channel Condition
Each assessment element is rated with a value of 1 to 10. Rate only those elements
appropriate to the channel. Using the Visual Assessment Protocol worksheet, record the
score that best fits the observations you make based on the narrative descriptions
provided. Unless otherwise directed, assign the lowest score that applies. For example,
if a reach has aspects of several narrative descriptions, assign a score based on the
lowest scoring description that contains indicators present within the reach. The length
of the assessment reach should be 12 times the active channel width or as otherwise
determined to best describe the existing conditions.
Pre -Flow Diversion Condition
Natural Channel; no
Evidence of past
Altered channel;
Channel is actively
structures, dikes.
channel alteration,
<50% of the reach
downcutting or
No evidence of
but with significant
with riprap and/
widening. >50% of
down -cutting of
recovery of channel
or channelization.
the reach with riprap
excessive lateral
and banks. Any
Excess aggradation;
or channelization.
cutting
dikes or levies are
braided channel.
Dikes or levees
set back to provide
Dikes or levees
prevent access to
access to an
restrict flood plain
the flood plain.
adequate flood
width.
lain.
10
7
3
1
Post -Flow Diversion Condition
Channel has not
Channel has been
Channel has been
Channel has been
changed since flow
altered since flow
altered since flow
altered since flow
removal. No further
removal, but with
removal. No
removal with
down -cutting or
significant recovery
recovery of
continuation of
lateral cutting.
of channels and
channels and
erosive actions.
banks.
banks.
10
7
3
1
Active downcutting and excessive lateral cutting are serious impairments to stream
function. Both conditions are indicative of an unstable stream channel. Signs of
channelization or straightening of the stream may include an unnaturally straight section
of the stream, high banks, dikes or berms, lack of flow diversity (e.g., few point bars and
deep pools), and uniform -sized bed materials (e.g., all cobbles where there should be
mixes of gravel and cobble). In newly channelized reaches, vegetation may be missing
or appear very different (different species, not as well developed) from the bank
vegetation of areas that were not channelized. Older channelized reaches may also
have little or no vegetation or have grasses instead of woody vegetation. Drop structures
(such as check dams), irrigation diversions, culverts, bridge abutments, and riprap also
indicate changes to the stream channel. Indicators of downcutting in the stream channel
include nickpoints associated with headcuts in the stream bottom and exposure of
cultural features, such as pipelines that were initially buried under the stream. Exposed
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footings in bridges and culvert outlets that are higher than the water surface during low
flows are other examples. A lack of sediment depositional features, such as regularly
spaced point bars, is normally an indicator of incision. A low vertical scarp at the toe of
the streambank may indicate downcutting, especially if the scarp occurs on the inside of
a meander. Another visual indicator of current or past downcutting is high streambanks
with woody vegetation growing well below the top of the bank (as a channel incises the
bankfull flow line moves downward within the former bankfull channel). Excessive bank
erosion is indicated by raw banks in areas of the stream where they are not normally
found, such as straight sections between meanders or on the inside of curves.
Hvdrologic Alteration
Flow is not evident.
Groundwater flow is
Groundwater flow is
Groundwater flow is
Channel is not
evident. Channel is
evident. Limited
evident. Moderate
incised any further
not incised any
channel incision.
channel incision..
than immediately
further than
after removal of
immediately after
flow.
removal of flow.
10
7
3
1
Bankfull flows, as well as flooding, are important to maintaining channel shape and
function (e.g., sediment transport) and maintaining the physical habitat for plants. The
channel and floodplain exist in dynamic equilibrium, having evolved in the present
climatic regime and geomorphic setting. The relationship of water and sediment is the
basis for the dynamic equilibrium that maintains the form and function of the channel.
The energy of the flow (water velocity and depth) should be in balance with the bedload
(volume and particle size of the sediment). Any change in the flow regime alters this
balance.
Evidence of flooding includes high water marks (such as water lines), sediment deposits,
or stream debris. Look for these on the banks, on the bankside trees or rocks, or on
other structures (such as road pilings or culverts). Excess sediment deposits and wide,
shallow channels could indicate a loss of sediment transport capacity. The loss of
transport capacity can result in a stream with three or more channels (braiding).
Vegetation
Significant
Moderate
Slight vegetation
No vegetation
vegetation growth
vegetation growth
growth since
growth since
since removal of
since removal of
removal of flow
removal of flow
flow defined as
flow defined as 35%
defined as 5% -
defined as less than
greater than 70%
- 70% vegetation
35% vegetation
5% of vegetation
vegetation
stabilizing soils.
stabilizing soils.
stabilizing soils.
stabilizing soils.
10
8
5
1
This element is the width of the natural vegetation zone from the edge of the active
channel out onto the flood plain. For this element, the word natural means plant
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communities with (1) all appropriate structural components and (2) species native to the
site or introduced species that function similar to native species
The 70% numeric benchmark is derived from an established practice used to evaluate
soil stabilization for storm water permits used in construction activity that involves land
disturbing activities.
Bank Stability
Banks are stable;
Moderately stable;
Moderately
Unstable; banks
banks are low (at
banks are low (at
unstable; banks
may be low, but
elevation of active
elevation of active
may be low, but
typically are high;
flood plain); 33% or
flood plain); less
typically are high
some straight
more of eroding
than 33% of eroding
(flooding occurs 1
reaches and inside
surface area of
surface area of
year out of 5 or less
edges of bends are
banks in outside
banks in outside
frequently); outside
actively eroding as
bends is protected
bends is protected
bends are actively
well as outside
by roots that extend
by roots that extend
eroding
bends (overhanging
to the base -flow
to the baseflow
(overhanging
vegetation at top of
elevation.
elevation.
vegetation at top of
bare bank,
bank, some mature
numerous mature
trees falling into
trees falling into
steam annually,
stream annually,
some slope failures
numerous slope
apparent).
failures apparent).
10
7
3
1
This element is the existence of or the potential for detachment of soil from the upper
and lower stream banks and its movement into the stream. Some bank erosion is normal
in a healthy stream. High and steep banks are more susceptible to erosion or collapse.
All outside bends of streams erode, so even a stable stream may have 50 percent of its
banks bare and eroding. The roots of perennial grasses or woody vegetation typically
extend to the baseflow elevation of water in streams that have bank heights of 6 feet or
less. The root masses help hold the bank soils together and physically protect the bank
from scour during bankfull and flooding events. Vegetation seldom becomes established
below the elevation of the bankfull surface because of the frequency of inundation and
the unstable bottom conditions as the channel moves its bedload. The type of
vegetation is important.
Signs of erosion include unvegetated stretches, exposed tree roots, or scalloped edges
should be noted. Estimate the size or area of the bank affected relative to the total bank
area.
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Water Appearance
Very clear, or clear
Occasionally
Considerable
Very turbid or
but tea -colored;
cloudy, especially
cloudiness most of
muddy appearance
objects visible at
after storm event,
the time; objects
most of the time;
depth 3 to 6 ft (less
but clears rapidly;
visible to depth 0.5
objects visible to
if slightly colored);
objects visible at
to 1.5 ft; slow
depth < 0.5 ft; slow
no oil sheen on
depth 1.5 to 3 ft;
sections may
moving water may
surface; no
may have slightly
appear pea-green;
be bright -green;
noticeable film on
green color; no oil
bottom rocks or
other obvious water
submerged objects
sheen on water
submerged objects
pollutants; floating
or rocks.
surface.
covered with heavy
algal mats, surface
green or olive-green
scum, sheen or
film.
heavy coat of foam
or
on surface.
Moderate odor of
or
ammonia or rotten
Strong odor of
eggs.
chemicals, oil,
sewage, other
pollutants.
10
7
3
1
Clarity of the water is an obvious and easy feature to assess. The deeper an object in
the water can be seen, the lower the amount of turbidity. Use the depth that objects are
visible only if the stream is deep enough to evaluate turbidity using this approach. For
example, if the water is clear, but only 1 foot deep, do not rate it as if an object became
obscured at a depth of 1 foot. This measure should be taken after a stream has had the
opportunity to "settle" following a storm event. A pea-green color indicates nutrient
enrichment beyond what the stream can naturally absorb.
Note: Given that the amount of water present in the effluent channel after the redirection
of the site effluent discharge via sub -surface piping is unknown, the Water Appearance
metric is subject to removal from future assessment consideration. If, upon removal of
the effluent discharge, storm water flow and/or groundwater is insufficient to maintain a
continuous presence within the effluent channel, vegetation will reclaim the majority (or
potentially all) of reaches and render the metric not applicable.
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Visual Assessment Protocol
Owners name Evaluator's name Date
Stream name Waterbody ID number
Reach location
Ecoregion
Applicable reference site
Land use within drainage (%): row crop
confined animal feeding operations
Weather conditions -today
Active channel width
Site Diagram
Drainage area
hayland grazing/pasture fo
_ Cons. Reserve industrial _
Past 2-5 days _
Dominant substrate: boulder gravel
Gradient
rest residential
Other:
sand silt mud
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Reach Assessment Scores
Channel condition 7
Hydrologic alteration ❑
Vegetation ❑
Bank stability ❑
Water appearance ❑
Overall score < 6.0 Poor
(Total divided by number scored) 6.1 — 7.4 Fair
7.5 — 8.9 Good
> 9.0 Excellent
Visual Assessment Score
Recommendations (Applies to Negative Stabilization Trends Only)
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Cumulative Reach Assessment Scores
Channel condition 1-1
Hydrologic alteration ❑
Vegetation F]
Bank stability F1
Water appearance ❑
Overall score < 6.0 Poor
(Total Reach Assessment Scores, for all reaches 6.1 — 7.4 Fair
assessed, divided by the number of reaches
assessed.)
7.5 — 8.9 Good
> 9.0 Excellent
Visual Assessment Score
Recommendations (Applies to Negative Stabilization Trends Only)
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