HomeMy WebLinkAboutLWRP Sound Shore Erosion Reach 3-Local Waterfront 1995David S. Corwin
639 Main Street
Greenport, NY 11944
March 1, 1995
The Honorable Ruth Oliva
Town of Southold
Main Road
Southold, NY
Subject: Waterfront Revitalization Erosion Study
Dear Ruth:
Enclosed please find a brief narrative, photographs and maps relating to the
Waferfront Revitalization Erosion Study, reach 3. Also enclosed is a time
sheet for January and February, 1995.
If you have any questions or ifI can be of further assistance in the
Waterfront Revitalization Study please contact me.
/~~ry truly/~ours, David S. Corwin
Southold Town Local Waterfront Revitalization Study
Long Island Sound Shore Erosion
Reach 3
February 1995
Submitted By:
David S. Corwin, P.E.
Reach 3
Table of Contents
Text ..................................................................... 1-4
Photographs ....................................................... 5-28
Map East Section ................................................ 29
Map West Section ................................................ 30
Reach 3
GEOMORPHOLOGY
Reach 3 is typical of Southold Town's north shore with bluffs as high as 60
feet to areas with no bluff at all such as Southold Town Beach and Inlet Point. The
bluffs between Horton's Point and Southold Town Beach are notable because of
their high clay content as compared to the typical loamy sand found in most bluffs
along Southold Town's north shore. The width of the beach ranges from 0 feet to
40 feet. Boulders are present on the majority of beaches alternating with areas that
consist of beaches with almost no boulders.
METHOD
The entire beach along Reach 3 was walked to locate areas of actual beach
erosion and notable shore protection strnctures. Visible inspection was augmented
by the first hand knowledge of the author, with a history of many years of
observation of the Long Island Sound shoreline and the descriptions of other
observers.
The shore line was inspected for areas of severe erosion. The December 24,
1994, storm was one of the worst storms in recent memory in terms of its erosion
effects. Areas that received minor erosion as a result of the December storm were
not included in the inventory of erosion. Erosion was classified as minor when it
resulted in inconsiderable erosion to the base of bluffs, insignificant lowering of the
beach grade or other events that would only be excepted in a storm with an
occurrence rate of about 20 years, which the December 1994 storm was judged to
be in terms of erosion.
Reach 3 was subdivided into 9 stretches that generally represent uniform
conditions throughout an area of beach, with stretch 1 at Horton's Point and then
continuing east.
OBSERVATIONS
Areas of moderate erosion are noted on the accompanying tax map in
orange. Areas of severe erosion are noted in yellow. Areas of hardened shoreline
(bulkhead, retaining walls and groins) are noted in blue. Areas where roads may be
threatened with erosion in the near future are noted in red. A series of photographs
was taken of notable structures and conditions along Reach 3. All photograph
locations and measurements are approximate.
The first 4,400 feet (stretch 1) east of Horton's point consists of high bluff
with a relatively broad beach strewn with boulders. This area is notable for a lack
of shore protection structures. The bluff in this area has experienced slides in many
locations. The erosion can best be categorized as moderate and was apparently the
result of the December 1994 storm. The lack of shore protection structures and the
Reach 3
apparent stability of beach access structures seem to indicate that this beach stretch
is relatively stabile.
An abrupt transition occurs approximately half way between Horton's Point
and Southold Town Beach. The high bluff continues but the broad beach and
boulders are no longer present. The beach is characterized by shore protection
structures as indicated in photographs 6 through 22. These photographs illustrate
the severe erosion that has occurred in this stretch. Stretch 2 includes Southold
Town Beach. Southold Town Beach is notable because it has no boulders and no
bluff. This public beach has experienced accelerating erosion as the storm patterns
have intensified over the past several years. The erosion of Southold Town Beach
appears to be aggravated by the two large groins just to the west of the beach area.
Stretch 3 is the area just east of Southold Town beach. It is a short stretch
of beach that is strewn with boulders. Stretch 3 is notable for its shore protection
structures and its stability. Stretch 3 contains two large groins at its east end.
Stretch 4 is a short stretch with no boulders and a low bluff. This area is
subject to severe erosion. The erosion is apparently aggravated by the groins at the
east end of stretch 3. These two groins are identified as number 2 and 3,
Hashamomuck Beach, page 36 of Thore Omholt's 1974 study. The construction of
these groins is dated in Omholt's study as 1955 and 1956. However, they were
reconstructed in the late 1960's. Three historical observers date the reconstruction
of these groins as the starting point for the severe erosion experienced in stretch 4.
Erosion in this stretch has reached a critical stage. Two dwellings were condemned
by the Southold Town building department after the December 1994 storm when
the foundations of the structures were damaged. This area has several shore
protection structures and more are in the process of being built. County Road 48 is
in peril from erosion in this stretch. This stretch has lost at least 50 feet of beach in
the past 30 years. Two rock groins have been built in this area, one in 1969 and
one in 1984. These groins have not been effective in holding beach material.
Stretch 5 is an area very similar to stretch 3 with boulders, shore protection
structures and a stable beach.
Stretch 6 is similar to stretch 4. The erosion along stretch 6, from the
account of one long term property owner, is not as severe as the erosion along
stretch 4. County Road 48 is in peril from erosion in this stretch.
Stretch 7 includes the area from the Sound View restaurant to about 2,000
feet east of Inlet Point. This stretch is notable for its lack of bulkheading and its
boulder strewn beach. One location just east of the Sound Shore motel is
interesting since a large pile of boulders acts as a natural groin. The Suffolk
County Department of Public Works is responsible for two precast concrete groins,
constructed in 1958, at the west end of this stretch to protect County Road 48. This
stretch is relatively stable. The beach in the area of the Sound View restaurant has
not changed in 25 years. The grade of the beach in front of the Sound Shore motel
eroded in the December 1994 storm. The beach along this stretch is stable. The
bluff area east of the motel and condominiums is notable for the lack of serious
erosion during the December 1994 storm. The east end of this stretch has a short
2
Reach 3
section of beach with no boulders in the vicinity of Iniet Pond. This section of
beach is notable as the only section of beach that has no boulders and is stable.
Stretch 8 is the area 2,000 feet east of Inlet Point to 1,000 feet west of the
Island's End golf coarse. This are can best be characterized as stable to moderate
erosion.
Stretch 9 includes the area from the golf coarse to Rocky Point. This stretch
is a stable beach.
CONCLUSIONS
The erosion experienced at various locations along Reach 3 is a function of
the quantity of natural boulders present, beach orientation in relation to tree north,
man made groins, natural groins, bulkheads and offshore topography. Some man
made groins have functioned satisfactory in holding the beach and done little
damage to adjacent beaches. The larger man made groins have resulted in stable
beaches to the west and severe erosion to the east.
The most important elements in determining erosion appears to be the
quantity of boulders on the beach, followed by the presence of large man made
groins. Most groin construction has taken place in boulder rich areas where the
material for construction is readily available. Where groins have been constructed
from imported rocks, they have not proven satisfactory due to the small size of the
rocks and the shifting nature of the beach itselfi This predisposes beaches free of
boulders to be susceptible to erosion.
The present policy of the New York State Department of Environmental
Conservation to allow groins only to the high water line, if at all, makes beach
stabilization difficult. Bulkheads are not a solution to the erosion problem and are
effective only in areas of stable beach.
Roads are in peril from erosion in three locations: the town road at Sound
View Avenue; County Road 48, 2000 feet east of Southold Town Beach and 200
feet west of the Sound View restaurant.
RECOMMENDATIONS
In an ideal world no construction would be allowed near the shoreline; it
would be preserved fo~ public access. This does not appear to be a policy that can
be pursued at this point in time.
The construction of bulkheads should be allowed to protect property that is
in jeopardy from erosion, however bulkheads alone are not effective. Properly
engineered groins should be allowed to help stabilize beaches. Existing groins
should be studied to determine which combinations of materials, lengths, heights,
permeability and location are effective. Groins should be allowed to extend past
the high water line in locations that have experienced severe erosion in an effort to
stabilize and rebuild beaches. Property owners who have constructed large groins
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Reach 3
should be encouraged to dismantle a portion of these groins. One mechanism for
dismantling of large groins may be through the power of the town trustees to
require permits for construction on or near the beach. When property owners
request related beach work such as cesspool construction and bulkheading, groin
downsizing could be required.
The construction of low profile timber groins should be encouraged. Low
profile timber groins have been effective on the bay and low profile steel groins
were effective on the ocean in rebuilding beaches after the hurricane of 1938.
The use of low profile timber groins has two advantages. One: beach material
spills over to adjacent beaches when the groin is full, rather then being redirected to
deeper water outside of the littoral drift. Two: the life of timber groins is limited so
that they could be monitored through the permitting process and permission to
rebuild them could be denied where they do not produce the desired result.
Parallel or offshore groins should also be considered. If sized properly for
the local conditions these structures may be effective in stabilizing beaches (see
photo 10). The Town should develop a set of standards for groin construction and
require that plans submitted for permit approval in severe erosion areas be made by
a professional engineer.
4
Reach 3
Typical erosion stretch 1
2. Typical erosion stretch 1
5
Reach 3 February 1995
3. Retaining wall
4. Close to the edge see photos 5 i
Reach 3 February 1995
§. Typical erosion to bluff; stretch 2
Failed bulkhead with 2" sheathing
7
Reach 3 February 1995
7. A structure precariously close to the edge. No bulkhead on either side.
8. Failed timber bulkhead (see photo 11 )
Reach 3 February 1995
Looking east. Beach held by a parallel or offshore groin.
10, Looking northwest. The effectiveness of a parallel or offshore groin
is apparent from these two photos.
Reach 3 February1995
Looking west, hardened shoreline, failed bulkhead
'12. I,ooking east, hardened shoreline. Notice ineffective concrete groin.
l0
Reach 3 February 1995
'13. Massive concrete seawall. Base of wall is being undermined.
'14. Concrete groin visible in photos 12 & 13. This groin is too short to
be effective and too high for access along the shore.
Reach 3
February1995
'16. This bluff was entirely covered with paving stones set in concrete in
the 1970's. The armor stretched from the base of the bluff to the top.
12
Reach 3 February 1995
.17. Littoral drift- a paving stone 250' east of the armored bluff in
15 &16.
'18. 750' east t bluff
'13
Reach 3 February t995
Failed bulkhead, possible public health hazard.
14
Reach 3
February 1995
20 8, 21. Looking east. A large groin effectively holds the beach. This
structure is too long and directs the littoral flow material to deep water
where it is lost to the littoral drift. The bar created by this groin can be
seen at low tide, when the wind is northwest, from Southold Town Beach.
Reach 3 February 1995
22. Failed rock gabions east of the second groin in photo 21.
Reach 3 February 1995
23. Sand placed over bluffin an attempt to stabilize it.
24. Looking west. Notice 2 groins in photo 2l. Sound View Ave. is
visible in left of photo.
Reach 3 February 1995
25. Ineffective west rock groin, stretch 4
26. Ineffective east rock groin, stretch 4
Reach 3
February 1995
27. Erosion damage, stretch 4
Reach 3 February 1995
28. West county groin, Sound View restaurant
29. East county groin. Sound View restaurant
2O
Reach 3 February 1995
30. West groin, Sound Shore motel
3'1. East groin at motel. Notice high timber groin which impedes acceSS
and traps all littoral drift.
21
Reach 3
February 1995
32. Grade drop in December 1994 storm is evidenced by exposed
drainage structure at motel.
33. Exposed drainage structure
22
Reach 3
Febmary1995
34. Grade drop is evidenced by paint line on pool at motel.
35. Natural rock groin, looking west
23
Reach 3 Febmary 1995
36. Natural rock groin, looking east
37. Typical beach} stretch 7
24
Reach 3 February1995
38. Natural groin
39. Typical erosion
25
Reach 3 February 1995
40. 67 Steps (Som~d Road end)
41. Rocks, looking west
26
Reach 3 February 1995
42. Rocks, looking south
43. Rocks, looking east
27
Reach 3 February1995
44. Rocky Point, looking west, low tide
45. Rocky Point, looking east, low tide
28
Reach 3 February 1995
3
I
!
REACH 3: HORTON POINT TO ROCKYPOINT
Pg.1 of 5
I': 727~
Map~West Section
29
Reach 3 February 1995
!
I
hood'
I
Map~East Section
I Average High Boulders Moderate Boulders
2 Narrow High Few Boulders Severe Clay Bluff Road in peril
3 ~ Average Low Moderate Boulders Stable Stable Beach
4 Narrow Low No Boulders Severe Erosion Road in peril
5 Average Low Moderate Boulders Stable Stable Beach
6 Narrow Low Few Boulders Severe Erosion Road in peril
7 Average High Boulders Stable Stable Beach
8 Average High Boulders Moderate Boulders
9 Broad High Moderate Boulders Stable Stable Beach
Table of Reach 3 Characteristics
31