CPE Letter to Coats re DMF Comments

Brad Rosov
Project Manager/Senior Marine Biologist
Coastal Protection Engineering of North Carolina, Inc.

4038 Masonboro Loop Road
Wilmington, North Carolina
Tel: [phone]
[e-mail]

August 17, 2021

Heather Coats
Division of Coastal Management
North Carolina Department of Environmental Quality
127 Cardinal Drive Ext.
Wilmington, NC 28405-3845

Subject:

Dear Ms. Coats,

On August 5, 2021, I received your email containing comments from the NC Division of Marine
Fisheries (DMF) regarding the Town of Kitty Hawk's CAMA Major Permit application for their
proposed beach nourishment project which is planned to go to construction during 2022. The comments
were drafted by James Harrison, DMF Fisheries Resource Specialist on July 16, 2021. In your email
you stated that the comments not only apply to the Town of Kitty Hawk's application, but also the
Towns of Duck and Southern Shores. DMF's comments include a recommendation for the
implementation of six monitoring protocols to be used to determine the effects of the proposed dredge
and fill beach activity on important nearshore fish and benthic species and habitats. I have formulated
responses to this recommendation and have addressed each of the six monitoring protocols individually
below. These responses are intended to provide you with some clarifications, additional context, and
information.

Requested Monitoring Protocol #1: Pre- and post-placement surveys of benthic species (biodiversity
and abundance) in order to determine the impact of dredging and placement on benthic species.

Over the past several decades, researchers have studied the impacts of beach nourishment projects on
benthic communities at dredge sites (aka borrow areas) and at fill placement sites through extensive
monitoring efforts. In doing so, these studies, which have taken place throughout the United States
including North Carolina, have generated a wealth of monitoring data resulting in a very good
understanding of the magnitude of impacts and anticipated recovery rates to benthic invertebrates
following beach nourishment events. As such, the applicants feel that additional monitoring efforts are
unwarranted. The information presented below is a summary of relevant findings derived from a number
of pre- and post-construction benthic monitoring efforts associated with beach nourishment projects from
throughout the United States.

First, it is widely recognized that dredge and fill operations associated with beach nourishment projects
cause the mortality of infaunal organisms found within the wet beach and benthic environments (Saloman,
1974; Oliver et al., 1977; NRC, 1995; USACE, 2001). Dredging activity involves the removal of
sediment, including the benthic infauna residing within the substrate. The placement of fill material upon
the beach and the intertidal area has the potential to smother and kill the existing infauna community
within the swash zone and nearshore benthic habitats. The resultant temporary loss of these lower trophic
level organisms has cascading effects on a wide range of species that prey upon them. These include
commercially and recreationally important fish as well as threatened and endangered species such as the
piping plover and red knot. As such, state and federal regulatory agencies had often required multi-year
pre- and post-construction infaunal monitoring program as a condition of a project’s permit in order to
document the effect these actions have on these important biological resources. The results of these
studies, dating back several decades, suggest a range of recovery rates that are determined largely by the
seasonality of construction and the kinds of construction practices used.

A recent study by Wooldridge et al. (2016) offered a useful summary of key peer-reviewed literature on
the subject. As cited in Wooldridge et al., recovery rates for benthic invertebrates at beach placement
sites were documented to be within one year or less for amphipods (Jones et al. 2008; Leewis et al. 2012;
Schlacher et al. 2012), mole crabs (Emerita spp.) (Hayden and Dolan 1974; Leewis et al. 2012; Peterson
et al. 2014), bean clams (Donax spp.) (Leewis et al. 2012) and polychaetes, most notably the spionid
polychaetes Scolelepis squamata (Leewis et al. 2012; Manning et al. 2014). Other studies cited in the
Wooldridge paper reported complete recovery within one year for these and other infaunal taxa such as
isopods and other bivalves (Burlas et al. 2001; Peterson et al., 2006, Jones et al. 2008; CZR Incorporated
and CSE, Inc., 2013; CZR Incorporated and CSE, Inc., 2014).

In a robust assessment of past studies within the primary and grey literature, Wilber et al. (2009) reviewed
a large body of monitoring studies, also analyzed previously by Peterson and Bishop (2005). In those
studies focusing on the intertidal macrofauna at fill sites, the reported macroinvertebrate recovery rates
ranged from less than one month (Gorzelany and Nelson 1983), less than one year (Parr et al. 1978; Jutte
et al 2002a and b), and to up to 2 years (Rakocinski et al. 1996). Factors contributing to the recovery rates,
as cited in these studies, included the seasonality of construction and the similarity of sediments used as
fill material to the native beach sediments. Projects incorporating well-matched sediments (with respect
to grain size, sorting, carbonate content, and percent fines) and construction periods that avoided the spring
recruitment pulse were associated with faster recovery rates. By contrast, springtime construction and a
poor sediment match (too coarse, shelly, or fine) led to longer recovery times.

Burlas et al. (2001) reached similar conclusions after a comprehensive study of impacts to intertidal and
nearshore benthos following a large beach nourishment project in New Jersey. Following initial declines
in biomass, abundance and taxa richness, the authors reported compete recovery of the intertidal
assemblages occurred between 2 to 6.5 months following the placement of beach fill. The authors also
concluded recovery was quickest when filling was completed by October, before the seasonal decline of
infaunal abundance occurred. When filling continued into the winter when the seasonal decline was
underway, the recovery times were longer; the authors postulated that timing of filling prevented
recolonization before the seasonal decline. It should also be noted that biological populations are
inherently variable and exhibit large natural abundance and diversity fluctuations at a site under same-
season comparisons. This natural variability poses a challenge to distinguish between natural and
nourishment-induced impacts without a high-frequency and high-density sampling program, which is time
consuming and expensive for quantitative analysis (Burlas et al., 2001).

The Nags Head beach nourishment project, completed in 2011, included benthic monitoring within the
fill placement area as well as the offshore borrow area. Project construction spanned the months of May

through October, during the peak period of benthic productivity. The 2013 Year 1 post-construction
report concluded that benthic populations in the nourished beach as well as the offshore borrow area
were not significantly different from control stations and demonstrated viable populations of organisms
as of the one-year sample event (CZR Incorporated and CSE, Inc., 2013). The Year 2 post-construction
monitoring report confirmed the results of the Year 1 report (CZR Incorporated and CSE, Inc., 2014).
Both reports concluded benthic populations along the beach as well as the offshore borrow area were
generally no different from control stations and demonstrated viable populations of organisms during the
post-construction sampling events (CZR Incorporated and CSE, Inc., 2014). Further, organisms living
in these "high energy" beaches may be better adapted to large-scale changes in the profile associated
with storms (e.g., CZR Incorporated and CSE, Inc., 2014).

In contrast to the above discussions, a number of recent studies have also reported substantially longer
recovery periods, or that no recovery of the infauna was observed through the duration of the monitoring
study (Colosio et al. 2007; Manning et al. 2014; Peterson et al. 2014; Wooldridge et al. 2016). However,
consideration of the construction practices implemented in the associated beach nourishment projects may
help explain the varied results, as well as provide valuable insight for best management practices of beach
nourishment projects. In a study conducted in Italy where three beaches were nourished at the same time
with varying levels of sediment compatibility, it was observed that the two beaches receiving poorly
matching sediments remained nearly free of macrofaunal organisms one year following nourishment. On
the beach that received sediment similar to the native beach, the macrofaunal assemblage did not differ
significantly from the non-nourished nearby beach following construction (Colosio et. al, 2007).

Other studies also demonstrate reduced recovery times that were likely driven by use of unnatural or
incompatible sediments for nourishment. A study by Manning et al. (2014) examined physical and
biological impacts resulting from two dredge spoil disposal events occurring in consecutive years (1999
and 2000) using sediments obtained from maintenance dredging of a navigation channel. The 1999
disposal event continued from April to June and therefore coincided with the spring recruitment period
for macroinvertebrates; by contrast the 2000 disposal event was completed prior to the benthic invertebrate
recruitment period. Results demonstrated that sites receiving the disposal material exhibited finer grain
size and an increase in sorting as compared to control sites. Invertebrate abundance subsequently remained
depressed for all taxa throughout the warm season except the polychaete Scolelepis squamata, which
responded positively to the finer sediments. Importantly, the disposal event occurring before the
recruitment period of benthos resulted in fewer negative impacts to abundance than the disposal project
conducted after the recruitment season. Although recovery occurred within one year after the 1999
disposal event, abundances were again depressed with the implementation of the second disposal event in
2000, highlighting the critical importance of adequate recovery periods incorporated into nourishment
cycles, as well as the potential adverse impacts associated with using nourishment material that is finer
than the native beach.

A study by Peterson et al., 2014 reported multi-year (> 3 years) impacts following two beach nourishment
projects that utilized “unnaturally coarse, shelly material”. Use of this material resulted in significant
increases in the proportion of gravel to total sediment weight of nourished beaches following nourishment
that persisted throughout the study and slowed the convergence of sediment properties between nourished
and non-nourished beaches. The percent by weight of gravel did not match sediments at control locations
until just over 3.5 years after nourishment occurred. Sampling revealed longer recovery rates for some
invertebrate taxa than has been reported for previous studies. Bean clams (Donax spp.) abundances
remained depressed by 70 to 90% for three to four warm seasons following nourishment when compared
to non-nourished control locations. Likewise, haustoriid amphipods exhibited significantly depressed
abundances throughout duration of the study (over 3.5 years) with no indication of trending toward
recovery. Mole crabs (E. talpoida) showed small, ephemeral responses to nourishment; abundances were

depressed in two years following nourishment, but not always statistically significant. Polychaetes
abundances were variable, and no indication of an effect of nourishment on abundances. Total biomass
of all macroinvertebrate taxa was depressed, but not significantly so, and recovered in one to two years.
This study also looked at indirect impacts to the predators of invertebrates, namely ghost crabs and
foraging shorebirds. The authors reported the effect on ghost crabs determined via burrow density counts,
was initially negative and most pronounced on the beach flat where sand was placed. However,
considerable recovery occurred by the following warm season, and the effect was no longer evident within
two warm seasons. The number of foraging shorebirds was substantially reduced, but recovered two to
three years after nourishment. The negative impacts on benthic infauna recovery associated with using
unnaturally course sediments for nourishment has also been suggested in other studies (Peterson et al.
2006; Manning et al. 2013)

Wooldridge et al.'s 2016 study reported that some infaunal taxa did not recover at the end of the 15-month
monitoring period despite using sediment that was deemed compatible with the native beach. The study
involved comprehensive sampling of invertebrates on eight beaches along the southern California coast.
Contrary to other studies, Emerita sp. and Donax sp. recovered within 1 year, while other invertebrate
taxa studied (amphipods and polychaetes) remained reduced in terms of density and abundance after 15
months of monitoring. Nourishment occurred in the fall; therefore it is possible that placement of fill
material depressed the population too late in the season and did not allow for recolonization prior to the
seasonal population decline, as has been suggested in other studies (Burlas et al. 2001).

As presented above, a wealth of data that has been generated over recent decades resulting in a
comprehensive understanding of the impacts to benthic resources in response to beach nourishment
projects. Some of the information presented above even includes the results from a recent benthic
monitoring study from a similar project (use of beach compatible sand with placement during the summer
months) from a nearby location (Nags Head). As such, the applicants feel that additional monitoring
efforts as requested by DMF are not necessary as the effects of the proposed activity is widely known.
Furthermore, Burlas et al. (2001) concluded that the natural variability of the benthic community poses a
challenge to distinguish between natural and nourishment-induced impacts without a high-frequency and
high-density sampling program, which is time consuming and expensive for quantitative analysis. In
conclusion, DMF's request for a single pre-construction monitoring event paired with two post-
construction monitoring events would most likely result in statistically insignificant results.

Requested Monitoring Protocol #2: Turbidity plume monitoring, to ensure increases in turbidity are
not causing significant impacts on the surrounding environment. Ideally, this would include
monitoring to observe how widespread the turbidity plume occurs during dredging and placement
operations. This should also involve taking water quality samples before, during, and after dredging
and disposal operations. At a minimum, this should be completed once per day, taking measurements
before dredging and placement at the dredging location and disposal site, and at least once during
dredging and once during placement. Specific parameters should include (at a minimum) turbidity (i.e.
secchi depth) and surface and bottom measurements of dissolved oxygen, temperature, and salinity.

Permits issued for the construction of the 2017 nourishment event within the Town's of Duck, Southern
Shores, Kitty Hawk, and Duck oceanfront shoreline did not include conditions requiring water quality
monitoring. Due the constant mixing of water driven by currents, tides, waves, and wind, water
temperature and dissolved oxygen levels in the nearshore environment of the Atlantic Ocean are typically
not impacted by the placement of beach fill material along the beach. As such, the applicant asserts that
daily water quality monitoring efforts for these parameters should not be required.

However, it is common practice during beach nourishment projects for the contractor to maintain sand
dykes on the beach in proximity to the outfall pipe as a means to control the turbidity levels within the
nearshore environment. This practice was successfully employed during the 2017 nourishment project
and the proposed project will include the same mitigation measure. If DMF or DCM raises concerns
regarding turbidity levels during the construction of the proposed project, a turbidity monitoring regime
could be implemented at that time.

Requested Monitoring Protocol #3: Habitat surveys at the disposal locations to ensure the projects are
not causing significant alterations in habitat type (i.e. SAV, wetlands, intertidal). In cases such as the
intertidal area, this would be to show that the placement of material isn't causing a significant shift in
habitat types that are based on water depths (removal of shallow habitat and/or conversion of shallow
habitat to deeper habitat, conversion of intertidal to subtidal, etc.).

As indicated in the applicant's Major CAMA permit application, no SAV or wetlands occur within the
project area and therefore no project-related impacts to those resources will be incurred as a result of the
proposed activity.

The characteristics of the borrow material utilized during a beach nourishment project helps to determine
the slope of the beach berm and the nearshore seafloor. Because the borrow area (Borrow Area A) used
for the 2017 nourishment event will be the same sand source for the proposed beach nourishment project,
the sediment characteristics (sediment grain size, % silt, sorting, etc.) will be very similar. Therefore, it is
expected that the beach will respond in a similar manner resulting in similar slopes along the beach,
intertidal areas, and nearshore subtidal areas. Accordingly, no discernable shifts in habitat types are
anticipated from this project.

Requested Monitoring Protocol #4: Monitoring for dead fish and crabs along placement - any deceased
fish/crabs observed in disposal areas (those in which the cause of death isn't obviously related to
recreational fishing) should be recorded and reported. This should also include monitoring, recording,
and reporting any fish/crabs that are caught and/or killed by dredging equipment. Recordings should
include, at a minimum, date/time/location observed, species, and length (tail length - measured in
centimeters from tip of the mouth to the tail fork; for crabs, measurement should be the width of the
carapace). Pictures are also helpful with this to ensure correct identification and for verification that
mortality is related to dredging.

The applicants will agree to making note of any dead fish or crabs observed by the construction observer
who will be on site at the beach fill location on a daily basis throughout the duration of the project. The
observer will record the date/time/location of each dead fish or crab and make note of the species, if
possible, along with length (tail length or carapace width). The protected species observer (PSO) aboard
the hopper dredge will make note of any dead fish or crab along with other fauna during dredging, however
due to physical constraints it may not be feasible to obtain individual specimens to take measurements. It
is unlikely that crabs or fish entrained by the dredge will be identifiable and therefore the applicants do
not feel it is practical to require monitoring for dead fish and crabs aboard the dredge.

Requested Monitoring Protocol #5: If possible, noise monitoring should be included. Ideally, this
would occur at varying distances from the dredge and disposal locations. Monitoring should include
recording noise levels before or after operations (to provide a baseline) and during the dredging and
disposal (to observe the increases that result from the dredging and disposal).

Ambient sound levels within coastal waters can vary seasonally and temporally, and are associated with
shipping and industrial sounds, wind-and-wave induced sound, and biologically produced sound
(Richardson et al. 1995). Reine et al. (2014) characterized ambient sound levels at an offshore borrow
area to be quite high; sound pressure levels (SPLs) averaged 117 dB re 1μPa at the upper listening depths
(3-m water depth) and 114.9 dB re 1μPa at the lower listening depth (9-m water depth). Overall average
ambient SPL at the offshore borrow area was 116.1 re 1μPa.

During dredging activities, noise levels will increase above the ambient levels at the borrow areas and
beach site due to the presence of construction equipment and personnel. Previous studies have already
revealed the typical noise levels that may be incurred during dredge and fill activities similar to what is
being proposed. Marine dredging produces broadband, continuous, low frequency sound that can be
detected over considerable distances and may trigger avoidance reactions in marine mammals (Thomsen
et al., 2009) and other organisms. The sound produced is dependent on many factors including, but not
limited to, substrate type, sediment type being dredged, type of equipment used and skill of the dredge
operator. The variation in noise emitted by equipment type is related to how the machinery makes contact
and extracts material from the sea floor. Clarke et al. (2002) performed a study of underwater noise
produced by various types of dredging equipment, including a hydraulic cutter suction dredge and a
trailing suction hopper dredge. Recordings of a hydraulic cutter performing maintenance dredging in
Mississippi Sound, Mississippi emitted noise as the cutterhead was turned at 1 – 10 rpm within the
substrate. Sounds were continuous and fell within the 70 to 1,000 Hz range while sound pressure levels
peaked between 100 to 110 dB re 1μPa rms. In the case of a hopper dredge, much of the sounds emitted
during the active dredging process are produced by propeller and engine noise, pumps and generators.
Similar to a cutter suction dredge, most of the sound energy produced fell within the 70 to 1,000 Hz range
and was continuous in nature. However, Clarke et al. (2002) reported peak pressure levels recorded by a
listening platform ranged from 120 to 140 dB re 1μPa rms for hopper dredges, which is comparatively
much higher than a cutter suction dredge. A more recent study evaluated sound levels produced by hopper
dredges operating in an offshore environment during sediment excavation, transport of material, and
pump-out of material (Reine et al., 2014). When averaged across all dredging activities, SPLs averaged
142.31 dB at a distance of 50 meters, and grew progressively less to 120.1 dB at 1.95 km. At all distances
from dredging activity, sound levels were highest during sediment removal activities and transition from
transit to pump-out, and were quietest during flushing of pipes at pump-out (132.45 dB). At a distance of
2.5 km, sounds attenuated to ambient levels.

Because the noise generated by beach nourishment projects such as what is being proposed for the four
beach towns in Dare County are already well understood, the applicants assert that noise monitoring is not
warranted.

Thank you for considering these responses to DMF's request to include monitoring activities as a condition
to the towns of Southern Shores, Kitty Hawk, and Kill Devil Hill's anticipated Major CAMA permits.
Please contact me anytime should you have any questions or need anything in addition.

Sincerely,
COASTAL PROTECTION ENGINEERING OF NORTH CAROLINA, INC.

Brad Rosov
Project Manager/Senior Marine Biologist