PLAN FOR VEGETATION REMOVAL AND RESTORATION IN ZONE B ON
WEST POINT ISLAND, MOBILE COUNTY, ALABAMA FOR THE
DEEPWATER HORIZON OIL SPILL RESPONSE
Prepared by
Barry A. Vittor & Associates, Inc.
8060 Cottage Hill Road, Mobile, Alabama 36695
FIGURE 1: BEACH ZONES
ZONE D
ZONE C
10ft Buffer Zone
Edge of dune or
associated vegetation
10ft line from the edge of dune or associated
vegetation
ZONE B
ZONE A
Not to Scale
Wrack line
Figure 2: VEGETATION TYPE A:
Small individual sprigs of vegetation not connected to other existing vegetation.
Figure 3: VEGETATION TYPE B:
Small clumps of vegetation scattered sporadically without evidence of sand accumulation
or dune elevation.
Figure 4: VEGETATION TYPE C:
Large clumps of vegetation scattered sporadically without evidence of sand accumulation
or dune elevation.
Figure 5: VEGETATION TYPE D:
Elevated mounds of vegetation in the process of dune formation and possessing
accumulated sand sporadically scattered.
INTRODUCTION AND GENERAL PROCEDURES
The presence of vegetation in Zone B should not ultimately drive the decision-making
process (i.e. whether to clean a specific location or not) but be complementary to it.
Efforts can be designed to minimize the impacts to the native vegetation and mitigate for
any negative impacts or take.
When possible, it is recommended that vegetated areas be generally avoided (additional
specifics are given below). If it is determined that a sparsely vegetated area requires
cleaning the least invasive option available should be utilized to help reduce impacts to
vegetation. Normally, the preferred choice would utilize manual techniques such as the
use of hand rakes. Appropriate methods for hand cleaning in vegetated areas (zone C and
D) have been included in this plan and are provided and discussed under the section on
Manual Cleaning
This plan allows for the take of vegetation within the beach areas on West Point Island
identified for power screening (Zone B; Figure 1) if the significant vegetation is restored
back to its original composition and species diversity. Small isolated individuals (Type A;
Figure 2) occurring within the beach zone are not considered a significant component of
the island’s vegetation. If Type A vegetation is present within Zone B, these plants can be
removed prior to cleaning and immediately replanted in the adjacent dune buffer area
approximately 18” apart (usually peformed by the NRAs). During the mapping of
vegetation within Zone B on January 19 and 20, 2011, all individuals of Type A
vegetation encountered were relocated outside of the beach zone. No individuals of Type
A plants are expected to be currently present within Zone B (having been relocated), but
workers are encouraged to be observant for any overlooked plants and aware of the
presence of vegetation in general. If additional Type A plants are encountered, they can
simply be removed by hand and relocated into the dune buffer.
Larger individuals (Types B and C; Figures 3 and 4) within Zone B can be removed and
replanted following power screening operations. Specifics on the methodology for
handling Type B and C vegetation is provided below. Spatially isolated patches of
vegetation in the process of dune formation and accumulating sand (Type D vegetation;
Figure 5) occasionally occur within Zone B. These larger clumps are typically not
associated with the primary dune vegetation and are often located some distance away
from the significantly elevated interior dunes in sand flats or over wash areas. Due to
their spatial position as isolated patches they can be easily avoided. These will be
delineated and marked with a 5-ft buffer and avoided. If roots become exposed when oil
cleaning operations commence, the buffer will be moved to a distance 5 feet from the end
of exposed root.
Specific recommendations on the best approaches to cleaning in and around vegetation
within the identified areas on Pelican Island are discussed below. The use of site specific
information and the professional judgment of the Project Botanist are considered an
important part of this approach and will benefit the process greatly.
MAPPING OF VEGETATION WITHIN ZONE B
Field visits to West Point Island were conducted by the Project Botanist on January 19,
20, and 23, 2011 to map areas of spatially isolated vegetation (Types B, C and D) within
Zone B. As described above, any Type A vegetation encountered within the area to be
power screened was carefully removed and immediately replanted outside of Zone B
within the buffer and primary dune areas. Care was taken to extract the entire plant with
miminal disturbance to the root material. When replanting Type A vegetation, an effort
was made to consider each species’ biology and specific habitat requirements (e.g.
elevation, substrate type, soil moisture, etc.) in deciding the appropriate location to place
relocated individuals. Type A vegetation was found to be extremely sparse and widely
distributed. Usually only single individuals were encountered within an area and these
were easily relocated outside of the beach area (Zone B). In areas containing multiple
individuals of Type A vegetation, the relocated plants were spaced randomly within the
buffer zone/primary dunes with a minimal spacing of 18 inches between individuals.
The ten-foot wide buffer zone (Zone C) delineating the boundary between the beach
(Zone B) and the primary dune system (Zone D) was established in the field by members
of the NRA with the assistance of the SCAT Liaison prior to the Global Information
Systems (GIS) mapping of vegetation. This task involved identifying the outer edge of
the primary dune vegetation (i.e. Zone D) and then measuring outward (towards the Gulf)
ten feet using a pre-measured rope representing the width of the buffer zone. The outer
boundary of the ten-foot wide buffer zone was physically marked with stakes.
The outer (seaward) limits of the ten-foot wide buffer zone were mapped using a Trimble
Pro-XR Global Position System (GPS) with sub-meter accuracy on January 19 and 20,
2011. This task typically involved follwing the established edge of the buffer (marked
with stakes) with the GPS set to collect line feature data generally using a one-second
collection interval (a five-second interval used in some areas). The faster collection
frequency allowed for a better mapping of the buffer which in some areas bent and angled
sharply to follow the irregular-shaped boundary of the primary dune vegetation. The
majority of the buffer zone was mapped by driving a utility terrain vehicle (UTV)
equipped with the Trimble GPS along its boundary. In areas where equipment and
workers precluded a close approach with an UTV due to safety reasons, this boundary
was walked by the Project Botanist carrying the GPS. The edge of the rack line along the
Gulf side of West Point Island was similarly mapped using a GPS by driving a UTV
along its boundary. A 1.2-mile linear section of beach located on the north side of West
Point Island near “Center Cut” was additionally identified for power screen cleaning.
This stretch includes segment lengths ALMO1-36 west to ALMO1-39. The boundary
for the targeted mechanical cleaning effort on this northern section (Mississippi Sound
side) of beach was also mapped with GPS.
MANUAL CLEANING IN ZONE C (10-FT BUFFER) AND ZONE D (PRIMARY
DUNES)
Impacts to vegetation are expected to be minimal for those areas where only manual
cleaning efforts will be performed. This non-invasive work will be conducted by trained
personnel using metal landscape rakes or plastic sifting rakes with mesh screens to
remove small tar balls within vegetated zones. Manual cleaning methods are used for
surface cleaning only. Surface cleaning is defined by the use of manual tools that go no
deeper than 2 inches from the surface. Having a qualified botanist familiar with beach
dune vegetation of the northern Gulf Coast present during clean-up efforts is suggested
but not required. This individual could assist in monitoring the manual cleaning around
sensitive vegetation and could be available in the field to guide workers on the best
approach to handling vegetation. NRA’s will be onsite to supervise at all times.
Generally, raking around widely spaced individual clumps of vegetation will be
permitted. Beach morning-glory (Ipomoea imperati: Figure 6) is one of the dominant
plant species within the vegetated work areas on West Point Island. Clean-up workers
should be trained to recognize this species vegetatively in the field as it can be easily
handled without difficulty (see below: Figure 7). Other species (e.g. sea oats, bitter panic
grass, gulf croton, gulf bluestem, sea purslane etc.) can be carefully raked if encountered.
The stolons of beach morning-glory growing along the surface of the sand can be
carefully lifted up and laid back out of the way. This technique is illustrated in Figure 7.
The growing tip is lifted and followed back to the origin of the tap root. Care should be
taken not to pull the plants up from the taproot. Lay the elongated stolon out of the way
of the area to be raked. If it is possible to lay the stolon outside of the work area that is
preferable, but in some cases this may not be possible. After raking, the stolons can be
replaced to their original position. Deeply buried stolons and seedlings can be gently
raked over the tops of the plants if the rake tines do not dig too deeply as to uproot the
plants.
http://luirig.altervista.org/photos/i/ipomoea_imperati.htm
Figure 6. Close-up view of beach morning-glory (Ipomoea imperati). Note the
somewhat fleshy leaves with cordate (heart-shaped) bases. Some individual leaves
are three-lobed and look fiddle-like. The creeping stolons can be seen on the
surface of the sand.
Figure 7. Illustration showing the recommended method for moving beach morningglory stolons
TAR MATS IN THE BUFFER ZONE
If a tar mat or seam is discovered in the buffer zone while performing manual cleaning as
described above, it can be manually removed to within 5 feet of the sensitive habitat or
associated vegetation, even if it requires digging deeper than 2 inches.
MECHANICAL POWER SCREENING
Vegetation Removal and Replanting Guidelines
An effort was made to identify every individual plant within the beach zone (Zone B)
during the field surveys performed on January 19, 20 and 23, 2011. It is recommended
that all workers be aware of the presence of vegetation and report to the NRAs any
unmarked plants suspected to be missed (not anticipated) or that may have voluntarily
germinated or spread into the areas to be cleaned. The Project Horticulturalist will also
be looking for plants as well. These waif individuals will be treated following the same
protocol laid out in this report.
Type A vegetation (Figure 2) has already been carefully removed and replanted outside
of Zone B into the adjacent buffer zone. The appropriate techniques for handling Type A
vegetation are discussed and addressed above. Figure 8 shows the Project Botanist
replanting an individual of Type A vegetation on West Point Island.
Individual plants and small isolated patches of vegetation spatially separated from the
primary dune system (Types B and C vegetation; Figures 3 and 4) can be safely removed
from beach areas (Zone B) and subsequently replanted in situ following cleaning if there
is not a significant accumulation of sand that forms an elevated mound surrounding the
vegetation (i.e. obvious dune formation has begun).
Figure 8. The Project Botanist replanting Type A Vegetation outside of Zone B.
All vegetation that has started to accumulate sand higher than the beach surface with
clear evidence of dune building/mounding (Type D vegetation; Figure 5) WILL BE
AVOIDED with a clearly marked 5-foot buffer from the edge of the vegetation. No
impacts to Type D vegetation will occur. The 5-ft avoidance buffer surrounding the Type
D vegetation has been physically established and marked in the field and is clearly visible
and recognizable.
All plants to be removed and replanted were mapped in the field using a Trimble Pro-XR
GPS with sub-meter accuracy. In most cases, the GPS positions of single individual
plants were recorded. These isolated plants were marked in the field with orange spray
plant to aid in their relocation (Figure 9). Some individuals were marked with a pink or
orange pin flag instead.
Occasionally, areas possessing a larger density of Type B and C vegetation were
identified. Instead of acquiring a GPS position for every single plant within these areas a
boundary delineating the limits of the vegetation was mapped by walking around the area
with the GPS collecting line feature data set with a 1-second collection frequency. A
total number of plants by species was then documented and recorded within the mapped
polygon. Vegetation within these polygons will be removed and replanted following the
guidelines in this report (see below).
Figure 9. Individuals identified for removal and replanting were marked with orange
spray paint and/or pin flags.
Vegetation that has been identified for removal should be harvested and used as material
for replanting. There may be instances (especially dormancy) where marked plants can
not be refound in the field for removal. In these cases, several options are recommended.
Existing nursery stock consisting of local material previously collected from Dauphin
Island may be used as an alternative for replanting if available. Another alternative is to
utilize plants targeted for removal. Some individuals may be separated into multiple plugs
and grown at a nursery to generate additional material for replanting. These can be used
as a substitution when a specific individual is not located in the field.
The replanting/restoration plan will determine the best location for replanting that would
enhance dune development in a polygon versus “corn row” configuration. Plants should
be approximately 18 inches apart with faster rooting plants on the outside of the polygon
and slower growing plants such as Sea oats in the interior.
Monitoring of the transplanted individuals will occur in June –July to document survival
and persistence of the vegetation and a return to pre-project conditions. If any mortality
of individual plants is found (as determined by the Project Botanist), nursery stock will be
used to replant the area up to the initial coverage in the month of July 2011. If nursery
stock (i.e. liners) are used to replant in July an 80% survival rate of nursery stock will be
guaranteed by the Horticulturalist at the end of 3 months (October 2011). If survival is
not successful the Horticulturalist will replant at their own cost.
RESULTS
Forty-three separate polygons of Type D vegetation representing a total of 0.4 acre were
identified within Zone B on West Point Island (see attached Maps 1 -18; Appendix A).
These areas are clearly marked in the field with a 5-foot avoidance buffer and no impacts
to these plants will occur. Species comprising Type D vegetation (i.e. with obvious
mounding of sand) include sea oats (Uniola paniculata), shoreline seapurslane (Sesuvium
portulacastrum), marsh fimbry (Fimbristylis castanea), marsh elder (Iva imbricata), and
bitter panicgrass (Panicum amarum). Figures 10 - 12 show examples of the avoided
Type D vegetation from West Point Island. Additional photographs of Type D vegetation
can be provided if requested.
Figure 10. Example of Type D vegetation found on West Point Island. Shown is
shoreline seapurslane ((Sesuvium portulacastrum).
Figure 11. Additional example of Type D shoreline seapurslane (Sesuvium
portulacastrum) found on West Point Island.
Figure 12. Additional example of Type D vegetation consisting of sea oats
(Uniola paniculata) and marsh elder (Iva imbricata)
One hundred and sixty-six (166) individual plants representing four species were
identified to be removed and replanted following power screening operations (Table 1;
Appendix B; Maps 1 -18). Several of these plants (approximately 14) are located along
the immediate edge of the buffer zone and may possibly be avoided during clean-up
efforts. Examples of the vegetation to be removed and replanted on West Point Island
are illustrated in Figures 13 and 14. Additional photographs of the vegetation targeted
for removal can be provided upon request.
Table 1. Total number of individuals by species to be removed and replanted on
West Point Island.
Species
Fimbristylis castanea
Panicum amarum
Sesuvium portulacastrum
Uniola paniculata
TOTAL
Number Identified for Removal
42
3
18
103
166
Figure 13. Example of Type B vegetation to be removed and replanted. Shown is an
individual of sea oats (Uniola paniculata).
Figure 14. Example of Type B vegetation to be removed and replanted. Shown is
shoreline seapurslane ((Sesuvium portulacastrum)
Appendix B gives the latitude/longitude coordinates and species for the vegetation to be
removed prior to cleaning. This information will be used to place the individuals back
into the same general vicinity after power screening efforts have taken plac.
SUMMARY
This report documents the vegetation occurring within the beach areas (Zone B) targeted
for mechanical cleaning on West Point Island. Forty-three polygons containing Type D
vegetation were identified inside Zone B representing a total of 0.4 acre. These areas will
be avoided with a 5-foot buffer surrounding the vegetation and no impacts to these plants
will occur.
One hundred and sixty-six (166) individual plants of Type B and C vegetation were
identified within Zone B for removal and subsequent replanting following mechanical
cleaning efforts. Monitoring of the transplanted individuals will occur in June –July to
document survival and persistence of the vegetation and a return to pre-project
conditions. If any mortality of individual plants is found (as determined by the Project
Botanist), nursery stock will be used to replant the area up to the initial coverage in the
month of July 2011. An 80% survival rate of nursery stock will be guaranteed by the
Horticulturalist at the end of 3 months (October 2011). If survival is not successful the
Horticulturalist will replant at their own cost.
No significant impacts to dune and beach vegetation are expected in following the
guidelines and recommendations laid out in this report.