HomeMy WebLinkAboutSE48_2824 Epsilon Response to Berman Independant Reviewer 2019 Annual review Comments 21_DEC_2020
PRINCIPALS
Theodore A Barten, PE
Margaret B Briggs
Dale T Raczynski, PE
Cindy Schlessinger
Lester B Smith, Jr
Robert D O’Neal, CCM, INCE
Michael D Howard, PWS
Douglas J Kelleher
AJ Jablonowski, PE
Stephen H Slocomb, PE
David E Hewett, LEED AP
Dwight R Dunk, LPD
David C Klinch, PWS, PMP
Maria B Hartnett
Richard M Lampeter, INCE
Geoff Starsiak, LEED AP BD+C
Marc Bergeron, PWS, CWS
ASSOCIATES
Alyssa Jacobs, PWS
Holly Carlson Johnston
Brian Lever
3 Mill & Main Place, Suite 250
Maynard, MA 01754
www.epsilonassociates.com
978 897 7100
FAX 978 897 0099
Projects:\21597\2013 Emergency Project\Monitoring and Work Reports\2019 Annual Report
December 21, 2020
Mr. Jeff Carlson
Natural Resources Director
2 Bathing Beach Road
Nantucket, MA 02554
Subject: DEP File No. SE48-2824 | Annual Report Review Comments
Dear Mr. Carlson:
On Tuesday December 15, 2020 I received the memorandum written by Mr. Greg Berman
dated December 8, 2020 presenting his review on the 2019 Annual Review. Thank you for
sending that along. Upon review of his comments, I offer the following responses to his
review. The major topics that he identified are paraphrased or copied verbatim and
presented in italics followed by responses is in normal typeface.
Executive Summary / Key Conclusion
Mr. Berman’s memo presents a comprehensive review of the 2019 Annual Review,
commenting on the major elements of: sand delivery, bluff monitoring, and underwater
video monitoring. Many of the comments he makes are on technical details and those are
addressed herein. His major comments are on the topic sand delivery to the template,
with the implication that the reported shortfall in sand delivered to the template is
depriving the fronting and adjacent beaches of sand. As we describe below it is not. 2019
sand deliveries were halted because of the perceived poor sand quality (which was
resolved after two rounds of testing and over 5 months of review) plus delays related to
COVID-19. However, because a large volume of sand is stored in the template, the
delivery deficit only effects the volume of sand on the template, not the sand available to
the littoral system. During the preceding six years approximately 13.8 cy/lf/yr of sand was
contributed off the template to the littoral system, and that volume exceeds the site-
specific historical annual average of 12.0 cy/lf/yr of sediment from the unprotected bluff.
Had the additional sand been delivered in 2019, the template would have been taller, but
there would not have been any difference in the amount of sand washed onto the beach
and into the littoral system. The materials in the 2019 Annual Review, quarterly reporting
by the Woods Hole Group, and summaries presented herein show that sand off the
Mr. Jeff Carlson 2 Nantucket Conservation Commission December 21, 2020
templates has contributed an adequate volume of sand to protect adjacent beaches. See
the attached plots of MLW position and Table 1 below.
Following are our responses to Mr. Berman’s review comments.
Section 4.1 Sand Delivery:
1. Table 1 shows a 16,459 cy of sediment deficiency from the required volume through
12/31/2019.
That is not in dispute. However, the implication being drawn by project opponents that
the volume of sand needed to protect the environment is not being provided is not true.
Nor is the deficiency new information to the Nantucket Conservation Commission
(“Commission”), the 2018 Annual Report showed a 12,682 cubic yard (“cy”) deficit
through April 30, 2018. The Siasconset Beach Preservation Fund (“SBPF”) made a good
faith effort going in to the 2019 sand year to make up for that deficit and provide the
annual 20,834 cy of sand. As you can see in Line 4 (2019 report Table 1) 23,335 cy of sand
was delivered in the 2019 sand year. The Polpis Harbor sand, approximately 10,000 cy,
was purchased and was planned to be delivered to the template in 2019. This delivery
however was prevented by the Commission while it evaluated the sand quality issue it
had raised. As you know, ultimately it was determined after five months of hearings and
studies that there was no contamination. Had it been allowed to be delivered in
December 2019, that sand delivery would have brought the total delivered through the
end of 2019 to approximately 33,335 cy – this would have approximated the known
volume needed to provide the annual volume and make up for the deficit (12,682 +
20,834 = 33,516 cy).
When one looks at the 2019 Table 1 one sees the sand deficit through 2018 is reported
as 18,960 cy not 12,862 cy. When preparing the 2019 report, after the period was closed,
we found a 6,278 cy spreadsheet error in the prior year report. That error was corrected
in the current report and we correctly reported the revised cumulative deficit of 16,459
cy of sand. The result is that had the Polpis Sand been allowed to be delivered in
December 2019 there would be an approximately 6,300 cy deficit versus the 16,459 as
reported.
2. The report also indicates on Line 14 of Table 1 that if the applicant were only required
to fill the template to 22 CY/LF then there would currently be a surplus instead of a
deficiency. However, this type of adaptive management has not been approved, …
SBPF proposed an adaptive sand management program in the 2016 Annual Report after
a detailed discussion with MassDEP, with Jeff Carlson in attendance. The idea of changing
to an adaptive management program was not rejected by Mr. Berman, see his comment
memo dated April 17, 2017. SBPF did not request an Amended OOC to modify the sand
mitigation protocol, but is considering that option going forward. The fact remains, that
following an adaptive management approach there was surplus of sand on the template
on 12/31/2019.
Mr. Jeff Carlson 3 Nantucket Conservation Commission December 21, 2020
Furthermore, if the project had been conditioned to provide the volume of sand
calculated in accordance with the accepted formula that the Commission and MassDEP
requires for any other coastal protection project on Nantucket or in Massachusetts, the
annual sand volume required would be 12.0 cy/lf/yr (not 22 cy/lf/yr) correlating to 11,364
cy/yr. On that basis, the six-year total required would be 68,184 cy (for the 947-foot-long
array). Total sand delivered to the template was 100,090 cy versus the 68,184 cy which
yields a 52,640 cy (or 177%) surplus.
3. … the surplus in the template combined with a deficit in nourishment volume may
indicate that the template may not be providing sediment to the beach system during
non-storm periods.
There has been no deficit in the sand nourishment volume contributed to the beach from
the template. The pre-geotube annual sand contribution rate off the bluff was 12.0
cy/lf/yr (length x height X retreat rate). Line 10 in Table 1 (2019 report) shows the actual
average annual sand contribution rate for the six-year reporting period was 13.8 cy/lf/yr
– somewhat higher than the pre-geotube annual average contribution rate calculated
from historic data. Therefore, there has been no shortage of sand contributed to the
littoral system during the post-geotube period. Furthermore, exposed geotubes are re-
covered after erosion events in compliance with the OOC. That means there is always
sand readily available on the face of the template to be eroded off and contributed to the
littoral system during the next storm. If there were no deficit and the 16,459 cy in question
had been delivered, there would be more sand on the template and the template would
be taller. There would be no difference in the amount of sand that washed onto the beach
feeding the littoral system.
4. Sand Years are actually time periods that range from as little as 3 months to as much
as 22 months …
We are moving the standardize the reporting year to calendar year. Sand Year 2020 is the
period 1/1/2020 to 12/31/2020.
5. It should be noted that the 20,735 deficient volume (which is less than 1% different
than one year’s requirement) calculated above does not take into account the 4,275
cy of sand in Line 10 of Table 1 which while “not initially placed as mitigation sand,
performed the same function and has been counted as such since is sloughed off the
bluff face and was pushed off the template” (email from Dwight Dunk with Epsilon).
If the +4,275 cy is added to the -20,735 cy then volume of -16,459 cy matches what is
reported in Line 13 of Table 1.
The +4,275 has been presented in each annual review since the 2,138 was carried forward
in 2015 and 2016. Neither the Commission nor the independent reviewer have
questioned this accounting before.
Mr. Jeff Carlson 4 Nantucket Conservation Commission December 21, 2020
6. The Sand Report stops at 12/31/2019 and it is currently almost 12 months after that
date. While it not known when Sand Year 2020 will end, if it were to end on
12/31/2020 the sand deficit would likely increase.
See response to comment #4 above.
7. According to the applicants there is 10,000 cy of compatible sand from Polpis Harbor
that will be placed during Sand Year 2020. This is less than half of the required amount
and will further increase the sand deficit. … If only the 10,000 cy from Polpis are added
then starting in 2021 the site will be 27,294 cy short of the required amount (-31,569
cy plus the +4,275 cy from Line 13 of Table 1). This will continue the trend of increasing
deficits over the last five years.
This is not disputed. During the first half of 2020 SBPF was prohibited from placing sand
on the template due to the COVID Emergency and the cease and desist issued by the
Commission. SBPF is placing the Polpis Sand now and weather permitting, delivery and
placement is expected to be completed by December 31, 2020.
Comments on Section 4.2 Bluff Monitoring:
8. However this reported high accuracy conflicts with the minor accretion for the area
above the geotubes of “approximately 0.37 feet (11.3 cm), which is about the vertical
accuracy range of the survey methods and likely represents no net change”. A
systematic offset of 4.5 inches (11.3 cm) is much greater than the reported 0.6 inches
(1.5 cm). This has been calculated as approximately 587 cy above the geotubes and
over 1000 cy in unprotected areas. The Sconset Bluff September 2019 Aerial Survey
Report postulates that these volumes “may either: 1) represent a minor amount of
sand accumulating at the toe of the bluff, or 2) represent values that are within the
vertical accuracy range of the drone survey.” The top and toe of the bank are used for
determining volume changes, the calculations utilized an elevation of 12 NAVD88 as
a proxy for the toe of the bank. The use of this proxy may also contribute to volumetric
errors if the break in slope changes between surveys. Examination of the profiles used
would be required to determine if some of this error is due to this reason.
The crux of the bluff monitoring reporting is the data shows accretion on the unprotected
bluff adjacent to and above the geotube array. See Figure 1 titled 2018 to 2019 Sand
Volume Comparison found in Attachment B – Sconset Bluff September 2019 Aerial Survey
Report. The data showed net gain “accretion” beyond just the toe of slope. There is no
sediment source to rebuild (accrete) sediment on the bluff face. Thus, there are two
potential reasons as we state: vertical accuracy of the survey or a slight increase at the
toe of slope from the littoral system. One other source of error on the slope above the
geotubes may the survey equipment is picking up a weak signal from vegetation rather
than the actual ground surface.
In either case the conclusion to be drawn from this data is that the bluff face adjacent to
and above the geotube system was fairly stabile during this monitoring period.
Mr. Jeff Carlson 5 Nantucket Conservation Commission December 21, 2020
9. The last independent review of this report recommended using the reported accuracy
to have a separate color for areas within the accuracy boundaries. For example, +/-
5cm would be gray instead of having just blue (loss) and red (gain), in order to show
areas that have minimal change too small to determine gain or loss. This was not done
in the Sconset Bluff September 2019 Aerial Survey Report.
The cumulative accuracy from the prior year plus the existing year approach the ranges
Mr. Berman proposes. In an academic setting examining the change to that level of detail
may be a goal. However, the purpose of this monitoring program is to determine the
stability or instability of the bluff, the volume of sediment contributed off the unprotected
bluff and the contribution of sand off the template. For this monitoring period we saw a
quiet storm pattern resulting in essentially no loss of sediment off the bluff (slight gains
at the lower elevations – see Figure 1 noted above) and a minimal volume of sand off the
template (Table 2 - Line 10 which shows 0.5 cy/lf/yr contributed off the template during
this monitoring period). These two observations are in alignment, and thus show that the
glacial landform and the template were rather stabile. This suggests that sand
contribution off the template and the unprotected bluff face followed similar trends
during this period.
10. … it is also important to show the accuracy in the volume estimates tables (ex. +/-
2,000 cy, +/- 2 cy/lf/yr). The Sconset Bluff September 2019 Aerial Survey Report
indicates that the estimates are at least +/- 2.1 CY/LF/YR, which is the unlikely
accretion rate determined for the “South Unprotected Area”.
We concur with this approach.
11. At present this uncertainly is a concern for determining appropriate erosion rates in
adjacent areas, as well as an accurately reported surplus of material in the sand
template.
There is some uncertainty relative the unprotected bluff face. However, the trend is more
important, i.e. that the trend of sediment off the unprotected bluff face and the
contribution off the template should both show similar trajectories.
Volume calculations of sand off the template measured during the bluff survey were also
checked against the sand volume deliveries and estimates of sand volumes pushed off the
template. Having more than one data source reduces the uncertainty the reviewer alludes
to for the template.
Comments on Section 4.3 Shoreline Monitoring:
12. The natural changes in this dynamic area continue to overshadow any signal that
might be from the geotube project. No additional shoreline change can be attributed
to the project at this time with the available data provided.
Mr. Jeff Carlson 6 Nantucket Conservation Commission December 21, 2020
We concur that this shoreline is a dynamic area and changes documented in the Woods
Hole Group (“WHG”) quarterly monitoring does not suggest the existing geotube system
has or is adversely affecting the fronting or adjacent beaches.
To support this statement we attach to this correspondence plots of the MLW position
from 1994 through September 2020 for Profiles 90 to 93, using the data from the most
recent WHG Shoreline Report. Examining the slope of the line of best fit shows the trend
in the MLW position. A negative line shows a downward slope (seaward movement of the
MLW line or erosion) while a positive slope shows an upward slope (landward movement
of her MLW or accretion). The absolute value of the slope indicates the rate of change; a
slope of “0” indicates no change, while the greater absolute value of the slope indicates
a greater the rate of change. A comparison of the slopes for the pre- and post-geotube
periods is presented below in Table 1. All slopes are close to 0 which indicates the relative
rate of change is low – close to zero – while the absolute values show a direction of the
trend.
Table 1. Comparison of MLW Position Trends (1994 – 2020)
Profile No. / Position Pre-Geotube
Slope
Post-Geotube
Slope Relative Change
93 / 1050 ft north -0.0024 +0.0011 Slight accretion
92.5 / 600 ft north -0.0047 -0.0035 Reduced erosion rate
92.2 / 300 ft north - -0.0061 Slight erosion
92.1 / 200 feet north - -0.0058 Slight erosion
92 / 100 feet north -0.0098 -0.0079 Reduced erosion rate
91.9 / north end - -0.0026 Stabile, slight erosion
91.5 -0.108 -0.0082 Increased stability, reduced
erosion rate
91.35 - -0.0004 Stabile, very slight erosion rate
91.2 - +0.0025 Stabile, slight accretion
91 -0.0138 -0.0005 Increased stability, reduced
erosion rate
90.95 / southern end - +0.0072 Stabile, slight accretion
90.9 / 100 feet south - +0.0073 Stabile, slight accretion
90.85 / 200 ft south - +0.0092 Stabile, slight accretion
90.8 / 300 ft south - +0.0123 Stabile accretion
90.6 / 600 feet south -0.012 -0.0008 Stabile, reduced erosion rate
90 / 1,200 ft south -0.0138 -0.0006 Stabile, reduced erosion rate
Grey shading indicates geotube system
Mr. Jeff Carlson 7 Nantucket Conservation Commission December 21, 2020
13. The WHG Report continues to use mean low water (MLW) for the vertical datum for
their shoreline change report, which is consistent across their surveys. However, the
Conservation Commission may want to request the values at each transect from the
edge of the geotube to MHW. This value will likely determine a “walkable” beach, and
by observing this value over time the Conservation Commission can determine if this
width is narrowing.
We do not disagree that monitoring MHW would be helpful. However, Special Condition
No. 27 required the continuation of the “beach monitoring/survey program currently
conducted by the Woods Hole Group” which had always monitored the MLW position.
The Woods Hole Group has added the MHW line to the profile plots in recent surveys.
Comments on Section 4.4 Underwater Video Monitoring:
14. Using video (and interpolating a raster from point data) alone is not the best
methodology to determine quantitative change in bottom type.
The use of photos / video is specified in Special Condition No. 28 which reds in part; “…
Photographs and/or video shall be taken along the transects within the project area and
the area directly adjacent to the project area. The underwater video shall be able to
characterize the bottom sediments, species present and relative abundance including the
calculating of the percent cobble where appropriate.”
15. The underwater sand forms in the area can be several feet high are likely migrating,
which would have more significance on bottom type than any above normal
contribution from the geotube sand contribution. The bottom type appears to exhibit
more seasonal change (06/2018-11/2018) than change over time (ex. 10/2016-
11/2019), as shown by the timeseries of bottom type maps below (modified from the
Video Survey Maps in the 2019 Epsilon Report).
The primary purpose of this monitoring effort is to monitor the extent of cobble / hard
bottom habitat. The concern was excess sand off the template into the littoral system
could cover the cobble / hard bottom. The purpose was not to monitor sand forms. We
agree the results show seasonal changes but do not shows changes in cobble / hard
bottom cover over time.
16. Summary of findings from the previous independent reviews of the Epsilon Reports:
• By holding this section of shoreline in place with geotubes while adjacent portions of
the coastal bank erode naturally, the array will eventually extend seaward further
than adjacent areas.
We strongly disagree with this comment about the efficacy of the project and believe it
should be stricken from the review. This comment is outside the bounds of the
independent reviewer’s role. The purpose of the independent reviewer is to review and
comment on the substance of the Annual Review and not present commentary on the
approved project.
Mr. Jeff Carlson 8 Nantucket Conservation Commission December 21, 2020
• The main uses of compensatory nourishment are to: ensure the beach in the
immediate vicinity of the project does not drop and change the coastal processes of
the immediate area, keep the geotube covered so it does not interact with
waves/currents, and to make up for any reduction in sediment available for downdrift
beaches.
We concur with this assessment of the purpose of the compensatory sand nourishment.
As documented in the Annual Review and reiterated herein, the average annual
contribution rate of sand off the template was 13.8 cy/lf/yr over the past six years. That
exceeds the pre-geotube contribution rate of the unprotected bluff which was 12.0
cy/lf/yr based on site-specific historic data. The comparison of MLW positions from WHG
data shows there is no accelerated loss of beach in front of or down drift from the geotube
system. See Table 1 above and the attached plots of MLW position.
The notion that the geotubes will not interact with waves or currents is preposterous. The
design of the geotube and sand template system is predicated on that interaction. That
interaction is needed so that sand can be washed off the face of the template and
contribute sand to the littoral system. The project management, and the OOC, requires
that exposed geotubes be re-covered after every erosion event; and that occurs after
every storm. Through the proper management of this project, over this six year reporting
period, adequate sand has been contributed to the littoral system, i.e. 13.8 cy/lf/yr > 12.0
cy/lf/yr, and there has been no adverse effect to fronting or adjacent beaches attributable
to this project. See the attached plots of MLW position.
• It appears that most of the offshore area is still >25% cobble/boulder, however point
data interpolation method selection can greatly affect the outcome. Sidescan
(backscatter) sonar images would provide a more complete picture of the bottom.
SBPF is following the monitoring procedure stipulated in the OOC.
• During lower wave energy the geotubes stay covered with sand and have minimal
negative interaction with coastal processes. During even minor storm events portions
of the geotubes are exposed, and are likely reflecting wave energy in a similar way to
a Coastal Engineering Structure (CES) during this period.
We do not disagree. However, the geotubes are designed and installed with a sloped face
to reduce wave reflection, and sloped faces do not reflect waves in the same manner as
a vertical face. Where a CES fronts a beach wave reflection can cause toe scour and
accelerated sand mobilization into the littoral system. The design of this CES is that sand
is designed to wash off the face of the template and be contributed to the littoral system
– that is how this CES is supposed to work. After erosion events exposed tubes, and if
needed toe scour and exposed ends, are re-covered and re-filled with sand off the
template. SBPF re-covers exposed geotubes and backfills toe scour end scour, if any, after
every erosion event so there is adequate sand available to be washed out during the
subsequent erosion event.
Mr. Jeff Carlson 9 Nantucket Conservation Commission December 21, 2020
• Due to the scale of this project (947’ length) there is a high potential for currents to
set up parallel to the smooth exposed geotube during storm conditions, which can
rapidly scour the end of the array.
We do not disagree. As discussed above, the design for this CES is that sand is washed off
the face and potentially at the toe so that sand is contributed to the littoral system – that
is how this CES is supposed to work. After erosion event exposed tubes, and if needed toe
scour and exposed ends, are re-covered and any toe scour and exposed ends are back
filled with sand off the template. SBPF backfills any toe scour after every erosion event.
• Erosion doesn't stop in areas adjacent to a shoreline stabilization project and "holding
the line" can become more and more difficult over time. An analysis on the useable
lifespan of the upland properties and eventual retreat (or abandonment) of the array
might be helpful.
We strongly disagree with this comment about the efficacy of the project and believe it
should be stricken from the review. This comment is outside the bounds of the
independent reviewer’s role. The purpose of the independent reviewer is to review and
comment on the substance of the Annual Review and not present commentary on the
approved project.
17. Despite the several years of deficiency negative impacts cannot be assumed simply
from the incomplete volumes delivered. Erosion at this section of shoreline is
punctuated by large storms, when large volumes are eroded quickly and then followed
by quieter periods of reduced erosion (or even accretion). It is more important that the
full volume is available during storms than strict compliance within a year (although
the sand year range of 3-22 months is already providing some flexibility).
We agree that the full volume of sand be available on the template (on the front face for
readily available sand during an erosion event and the top as the on-site stockpile to re-
cover exposed geotubes) rather than strict compliance with the annual amount. To date,
adequate sand has been delivered to the template and used to contribute sand to the
littoral system to protect the fronting and adjacent beaches. The average annual
contribution of sand off the template exceeds the calculated rate of the bluff section now
protected by the geotube system (13.8 cy/lf/yr > 12.0 cy/lf/yr).
18. Exposure of the geotube array for extended periods due to the lack of sand will likely
result in negative effects. Additionally, if there are direct observations of increased
erosion downdrift of the geotube array, then a portion of that erosion may be due to
the reduction in volume provided by the project.
Monitoring to date (six years of data) demonstrates that the template has been managed
in a responsible manner to provide adequate sand to the littoral system to protect the
fronting and adjacent beaches. See Table 1 above and the attached plots of MLW position.
In general, since the geotube system was installed one observes that the erosion rate of
the fronting and adjacent beaches has slowed and at some profiles shows accretions as
Mr. Jeff Carlson 10 Nantucket Conservation Commission December 21, 2020
compared to the pre-geotube period. No observed or documented damage to adjacent
beaches is identified from review of the quarterly shoreline monitoring reports.
This project meets the performance standards established for CES’s which were
established to protect the interests of the Wetlands Protection Act (“WPA”) and the
interests of Nantucket Wetlands Bylaw. The interests presumed significant to Coastal
Bank are storm damage prevention and flood control. The geotube system has positively
affected the ability of the Coastal Bank to protect those interests. Secondly, the
regulations require that CES’s have no adverse effect to downdrift beaches. As stated in
several places herein the data shows no adverse effect to fronting and adjacent beaches
attributable to the geotube system. See Table 1 above and the attached plots of MLW
position.
We appreciate you taking these responses into consideration when reviewing Mr.
Berman’s review. In accordance with the OOC we expect to discuss the 2019 Annual
Review with the Commission at some time in the future.
Contact me at ddunk@epsilonassociates.com or by phone at 781.710.7305 with any
questions regarding this correspondence.
Sincerely,
EPSILON ASSOCIATES, INC.
Dwight R. Dunk, LPD, PWS, BCES
Principal
encl.
cc. J. Posner, SBPF
S. Cohen, Cohen & Cohen Law PC
G. Wood, Rubin and Rudman LLP
BAXTER ROADSANKATY ROADSANKATY
HEAD
ROADISABELLE'S WAYPOL
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ANNES LANE
BAYBERRY LANE
ELDRIDGE LANE
90.890.9
91.2
91.9
92.2
92.1
91.35
90.85
90.95
0
0
700
600
500
400
300
200
100
700
600
500
400
300
200
100
800 feet
800 feet
88
89
90
91
93
94
88.6
89.2
89.8
89.5
90.6
91.5
92.5
93.5
63
69
71
67
65
85
99
97
87
73
83
101
105
109
81
79
93
91
77
117
75
115
113
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107
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Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS,AeroGRID, IGN, and the GIS User Community
G:\Projects\Lighthouse\2019\MXD\14-project_area_REV_20190812.mxd
Figure 14Shoreline Monitoring Survey Transects - Project Area
Expanded Baxter Road and Sconset Bluff Stabilization Project Nantucket, MA
LEGEND
Basemap Imagery: 2013 Col-East/2011 ESRI
Participating Properties
WHG Survey Line
°0 200 400100
Feet1 inch = 400 feet
Scale 1:4,800
y = -0.0024x + 45.734 y = 0.0011x - 99.4
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Oct-95 Dec-99 Jan-04 Feb-08 Apr-12 May-16 Jun-20Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 93 since November 1994
Pre-Geotube Post-Geotube Linear (Pre-Geotube)Linear (Post-Geotube)
Pre-Geotube Slope =-0.0024 Post-Geotube Slope = +0.0011
y = -0.0047x + 143 y = -0.0035x + 96.316
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Oct-95 Dec-99 Jan-04 Feb-08 Apr-12 May-16 Jun-20Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 92.5 since November 1994
Pre-Geotube Post-Geotube Linear (Pre-Geotube)Linear (Post-Geotube)
Pre-Geotube Slope =-0.0047 Post-Geotube Slope = -0.0035
y = -0.0061x + 249.84
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Apr-14 Sep-15 Jan-17 May-18 Oct-19 Feb-21Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 92.2 since October 2014
Post-Geotube Linear (Post-Geotube)
Post-Geotube Slope = -0.0061
y = -0.0058x + 245.25
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Apr-14 Sep-15 Jan-17 May-18 Oct-19 Feb-21Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 92.1 since October 2014
Post-Geotube Linear (Post-Geotube)
Post-Geotube Slope = -0.0058
y = -0.0098x + 343.12 y = -0.0079x + 273.66
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Oct-95 Dec-99 Jan-04 Feb-08 Apr-12 May-16 Jun-20Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 92 since November 1994
Pre-Geotube Post-Geotube Linear (Pre-Geotube)Linear (Post-Geotube)
Pre-Geotube Slope =-0.0098 Post-Geotube Slope = -0.0079
y = -0.0026x + 112.95
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Apr-14 Sep-15 Jan-17 May-18 Oct-19 Feb-21Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 91.9 since October 2014
Post-Geotube Linear (Post-Geotube)
Post-Geotube Slope = -0.0026
y = -0.0108x + 367.4 y = -0.0082x + 272.03
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Oct-95 Dec-99 Jan-04 Feb-08 Apr-12 May-16 Jun-20Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 91.5 since November 1994
Pre-Geotube Post-Geotube Linear (Pre-Geotube)Linear (Post-Geotube)
Pre-Geotube Slope =-0.0108 Post-Geotube Slope = -0.0082
y = -0.0004x + 11.494
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Apr-14 Sep-15 Jan-17 May-18 Oct-19 Feb-21Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 91.35 since October 2014
Post-Geotube Linear (Post-Geotube)Linear (Post-Geotube)
Post-Geotube Slope = -0.0004
y = 0.0025x - 111.23
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Apr-14 Sep-15 Jan-17 May-18 Oct-19 Feb-21Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 91.2 since October 2014
Post-Geoprobe Linear (Post-Geoprobe)
Post-Geotube Slope = +0.0025
y = -0.0138x + 450.88 y = -0.00005x - 106.22
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Oct-95 Dec-99 Jan-04 Feb-08 Apr-12 May-16 Jun-20Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 91 since November 1994
Pre-Geotube Post-Geotube Linear (Pre-Geotube)Linear (Post-Geotube)
Pre-Geotube Slope =-0.0138 Post-Geotube Slope = -0.00005
y = 0.0072x - 312.93
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Apr-14 Sep-15 Jan-17 May-18 Oct-19 Feb-21Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 90.95 since October 2014
Post-Geotube Linear (Post-Geotube)
Post-Geotube Slope = +0.0072
y = 0.0073x - 316.49
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Apr-14 Sep-15 Jan-17 May-18 Oct-19 Feb-21Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 90.9 since October 2014
Post-Geotube Linear (Post-Geotube)
Post-Geotube Slope = +0.0073
y = 0.0092x - 399.26
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Apr-14 Sep-15 Jan-17 May-18 Oct-19 Feb-21Shoreline Chnage (ft)Date
Cumulative Shoreline Change (ft) at 90.85 since October 2014
Shoreline Change Linear (Shoreline Change)
Post-Geotube Slope = +0.0092
y = 0.0123x - 533.2
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
30.0
Apr-14 Sep-15 Jan-17 May-18 Oct-19 Feb-21Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 90.8 since October 2014
Post-Geotube Linear (Post-Geotube)
Post-Geotube Slope = +0.0123
y = -0.012x + 366.28 y = 0.0008x - 130.21
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
Oct-95 Dec-99 Jan-04 Feb-08 Apr-12 May-16 Jun-20Shoreline Change (ft)Date
Cumulative Shoreline Change (ft) at 90.6 since November 1994
Pre-Geotube Post-Geotube Linear (Pre-Geotube)Linear (Post-Geotube)
Pre-Geotube Slope =-0.012 Post-Geotube Slope = +0.0008
y = -0.0138x + 416.58 y = -0.0006x - 90.913
-190.0
-170.0
-150.0
-130.0
-110.0
-90.0
-70.0
-50.0
-30.0
-10.0
10.0
Oct-95 Dec-99 Jan-04 Feb-08 Apr-12 May-16 Jun-20Shoreline Chnage (ft)Date
Cumulative Shoreline Change (ft) at 90 since November 1994
Pre-Geotube Post-Geotube Linear (Pre-Geotube)Linear (Post-Geotube)
Pre-Geotube Slope =-0.0138 Post-Geotube Slope = -0.0006