HomeMy WebLinkAboutEGD-14-05
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REPORT
ENGINEERING SERVICES
Meeting:
GENERAL PURPOSE AND ADMINISTRATION COMMITTEE
Date: Monday April 25, 2005
Report #: EGD-14-05
File#:
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By-law #:
Subject:
PORT OF NEWCASTLE CONCEPTUAL WATERFRONT PLAN
RECOMMENDATIONS:
It is respectfully recommended that the General Purpose and Administration Committee
recommend to Council the following:
1. THAT Report EGD-14-05 be received;
2. THAT Phase One of the Conceptual Waterfront Plan for the Port of Newcastle be
approved as a guide for the development of a linear waterfront park;
3. THAT staff be authorized to negotiate with Kaitlin for additional waterfront land at the
mouth of the Graham Creek and to re-grade the bluff along Lake Ontario; and
4. THAT the proposed erosion control works be referred to the Capital Budget and
Forecast.
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Submitted by: A.S. Cannella, C.E.T. Reviewed by: Franklin Wu,
Director of Engineering Services Chief Administrative Officer
ASC/PW/jo
April 20, 2005
CORPORATION OF THE MUNICIPALITY OF CLARINGTON
40 TEMPERANCE STREET, BOWMANVILLE, ONTARIO L lC 3A6 T 905-623-3379 F 905-623-9282
REPORT NO.: EGD-14-05
PAGE 2
1.0 BACKGROUND
Through development of the Port of Newcastle subdivision, the Municipality will acquire a
900m long continuous block of District parkland along the Lake Ontario shoreline
between Toronto Street and the west edge of the Region of Durham Water Treatment
Plant. Additionally the Municipality was granted a 300m long, 15m wide easement from
the Kaitlin Group along the waters edge from the east side of the Region's Plant to the
pier at the Graham Creek (Attachment 1).
The land is intended to be developed as a linear waterfront park with connections to the
Samuel Wilmot Nature Area to the west and Graham Creek to the east. Most of the land
sits atop a steep bluff 9m to 13m above the level of Lake Ontario.
In 2000 The Kaitlin Group, the developers of the subdivision, engaged Marshall Macklin
Monaghan Ltd. to work with the Municipality and prepare a conceptual waterfront plan for
all of the lands described above. A series of public meetings were held to obtain
resident input and a peer review by an independent consultant was used to finalize the
conceptual plan. The plan was prepared to provide a conceptual guide for the future
development of the parkland and to submit for a second round of SuperBuild funding
which did not occur.
A key recommendation of the plan is to improve site safety by re-grading the bluff to a
2:1 slope. Kaitlin is currently preparing to develop the western portion of their Port of
Newcastle subdivision. As part of that development they can accommodate the fill
material generated by re-grading the bluff. They have offered to do the work at their own
cost and move the fill material to their next phase of residential development in 2005. If
the bluff grading is not done in 2005 then the Municipality would have to re-grade the
bluff and truck the fill away from the site in the future.
2.0 CONCEPTUAL WATERFRONT PLAN
The location and elevation of the parkland provides a number of opportunities and some
significant constraints to development of a District Park. People will be drawn to the area
REPORT NO.: EGD-14-05
PAGE 3
for the views out over the lake and proximity to the waters edge. The parkland is also
directly adjacent to the Samuel Wilmot Nature Area and is ideally suited for the
development of a passive linear park with some active nodes and parking lots on wider
portions of the site. The prominent feature of the conceptual waterfront plan will be the
development of a 3m wide trail that would meander along the parkland overlooking the
lake. The trail would connect to the Samuel Wilmot Nature Area at the west end of the
site. At the east end the trail would swing north at the Region's Water Treatment Plant
and follow local roads to connect with the existing trail along the Graham Creek at the
rear of Carveth Crescent. Due to the potential difficulties and high cost of creating a
pedestrian link across the Graham Creek it is proposed that the Waterfront Trail continue
north along Port of Newcastle Drive and then south on Mill Street to connect to Bond
Head and eventually Lakeshore Road.
2.1 PHASE ONE PARK DEVELOPMENT (Attachment 2)
The 7.35 ha (18 acre) park from the Region's Water Treatment Plant west to Toronto
Street would be predominately passive in character and will include:
. an 800m long, 3m wide asphalt waterfront trail
. connecting trails leading from the various park features to adjacent roads and
parking lots
. seating areas and lookout platforms located along the top of the bank providing
vistas out over Lake Ontario
. flexible open lawn areas for events or multi-use activities
. a parkette at the south end of Port of Newcastle Drive will be the focal point of
phase one and will be the main access point from the neighbourhood to the park. It
would include play grounds, seating areas and a gazebo
. two public parking lots along the south edge of Lakebreeze Drive
. landscaping including seeding, sodding and tree planting
The existing bluff is a significant constraint to providing a safe and accessible park. The
conceptual waterfront plan proposes to reduce the bluff by re-grading it to a 2:1 slope,
and protect the shoreline from further erosion with armour stone.
REPORT NO.: EGD-14-05
PAGE 4
The preliminary cost estimate for Phase One of the conceptual waterfront plan, from the
Region's Water Treatment Plant to Toronto Street, not including bluff grading or
shoreline stabilization, is $1.1 million.
2.2 PHASE TWO PARK DEVELOPMENT (Attachment 3)
It has yet to be determined how much public land will exist east of the Regional Water
Treatment Plant. This portion of the conceptual waterfront plan is currently in Kaitlin's
ownership, with the Municipality having a 15 m easement along the lake edge. The
Municipality is currently in discussions with Kaitlin to determine the extent of potential
public park space. The conceptual waterfront plan proposes higher order active facilities
in this area such as tennis courts, water play, an event area with bandshell/pavilion,
formal gardens a washroom building, and community meeting rooms. This portion of the
conceptual waterfront plan may require revision or a joint use agreement depending on
whether the land is owned, developed, and maintained by the Municipality.
The park development at the mouth of the Graham Creek and south of the Brig would be
Phase Two of the District Park development. The timing of this phase could be
coordinated with Kaitlin's proposed development in that area. The estimated cost to the
Municipality for Phase Two will depend on the amount of public land obtained in this
portion of the site and proposed uses.
3.0 COASTAL ENGINEERING ASSESSMENT
The waterfront lands for the park include approximately 760 meters of existing bluffs. To
increase public safety the conceptual waterfront plan proposes to eliminate the bluff by
re-grading at a 2:1 slope and installing toe protection at the waters edge to control
erosion. At selected locations a terraced access pathway could be incorporated into the
slope to provide closer access to the waters edge.
REPORT NO.: EGD-14-05
PAGE 5
W.F Baird and Associates - Coastal Engineers were retained to review the conceptual
plan specifically as it relates to coastal engineering issues. The objective of the study
was to assess and report on the technical and engineering aspects of the proposed
stabilization works. The study focused on two primary tasks:
1) Provide a description of the cohesive shoreline and establish shoreline recession
rates.
2) Review the proposed stabilization method and provide alternative approaches.
3.1 GENERAL SHORELINE DESCRIPTION
Typically the shoreline along the south edge of the parkland is dominated by steep bluffs,
which rise 9m to 13m above the lake. The eroding bluff shoreline is classified as a
"cohesive shoreline". Approximately 40% of the lower Great Lakes shorelines are
cohesive. The bluffs are glacial till with minimal vegetation on the steep bluff face,
indicating ongoing erosion. A relatively narrow coarse sand, gravel, and cobble beach is
located along the base of the bluff. The beach width varies with fluctuations in water
level. Ownership of the lakebed up to the high water mark rests with the Crown under
the jurisdiction of the Ontario Ministry of Natural Resources.
Using air photos, Baird was able to calculate the amount of erosion since 1955 along the
760m stretch of bluff. In general, the easterly portion of the bluff has retreated a greater
distance, typically 9m to 20m since 1955; average annual rate .2m to .45m (8"-18" per
year).
The westerly portion of the bluff has retreated 3m to 9m since 1955; average annual rate
less than .2m (8" per year).
Without some means of protection the erosion of the cohesive shoreline material is
irreversible and ongoing.
REPORT NO.: EGD-14-05
PAGE 6
3.2 SHORELINE PROTECTION ALTERNATIVES
At existing rates the bluff would retreat 20m to 40m over a period of 100 years. If
remedial action is not taken the waterfront access and parkland will eventually be lost.
The existing high steep bluff also poses a risk to those using the parkland.
Armour Stone Revetment
The conceptual waterfront plan recommends a basic armour stone revetment at the
waters edge. This can provide some shore protection for a period of time, but is not a
long term solution.
The controlling process for erosion of the bluff is the downcutting or downward erosion
of the lakebed by wave induced forces. For effective long term shore protection the
design must not simply armour the waters edge but must extend to the lake bottom to
eliminate the downcutting that causes the erosion. A typical revetment structure must be
of sufficient size and height to resist wave attack and ice forces. It would crest above
lake level and extend directly into the water (Attachment 4). The slope of the structure
face would not allow access by people to the waters edge and the existing cobble beach
would be eliminated. This type of revetment has been used effectively along the
Scarborough Bluffs. In Scarborough the revetment structure was built, but the bluffs
have not been re-graded. Instead they have been allowed to self stabilize. Both re-
grading and self stabilization result in the loss of tableland at the top of the bluff. The
cost of a full revetment structure would be in the order of $2,000 per linear meter of
shoreline protected.
Maintaining the existing width of tableland at the top of bluff would require massive
quantities of fill extending approximately 20m into the lake to achieve a 2:1 slope. This is
not considered a feasible approach for this project because of the high cost and impacts
on fish habitat. The main elements of the conceptual waterfront plan could still be
constructed despite the loss of tableland.
REPORT NO.: EGD-14-05
PAGE 7
Detached Breakwaters and Artificial Headlands
Detached breakwaters are island structures made of stone that are located 100m to
150m offshore parallel to the shoreline (Attachment 5). They are intended to reduce
wave energy before reaching the shoreline. They can be constructed as a continuous
structure or a series of structures separated by gaps and they can extend above the
water level or be submerged just below the water level.
Artificial headlands are similar to detached breakwaters except that they typically have
some form of perpendicular connection to the shore to contain alongshore transport of
sediment (Attachment 6). They are generally located closer to the shoreline. Artificial
headlands are often used to protect and retain placed beach material.
The two primary advantages to detached breakwaters and artificial headlands are:
1) The erosion protection is located offshore which permits the preservation or
enhancement of the existing shoreline.
2) The beach area created behind the breakwaters or headlands provides a valuable
waterfront resource for public use.
The disadvantages of detached breakwaters and artificial headlands are:
1) The extent of lake bed occupied by the structures and the beach fill are significant and
would be subject to extensive review under the federal Fisheries Act.
2) There could be potential impacts on downdrift shorelines that would have to be
assessed.
3) High cost, typically $4000 per meter of protected shoreline.
4.0 CONCLUSION
The Municipality will own or have access easements over most of the land along the
Lake Ontario shoreline between Toronto Street and the mouth of the Graham Creek.
The land will be a valuable resource for public use and enjoyment. The conceptual
waterfront plan prepared for the land is appropriate as a guide for the future development
of the parkland. The parkland will most likely develop in phases and detailed design for
REPORT NO.: EGD-14-05
PAGE 8
each phase will carefully examine proposed uses in context with the recreational needs
of the area and site conditions.
With the ownership of the land comes the responsibility for controlling the erosion of the
bluff. Without some means of protection the erosion of the Port of Newcastle shoreline is
irreversible and ongoing. If the Municipality intends to construct a linear waterfront park
adjacent to the eroding shoreline a long term solution must be implemented. Based on
the effectiveness and cost of the various shoreline protection alternatives, it is
recommended that armour stone revetment be installed along the 760m of existing bluff
at an estimated cost of $1.5 - $2 million. The bluff should also be re-graded to a 2:1
slope for the protection of the public using the park.
Kaitlin, the subdivision developer, has confirmed that they could accommodate the fill
material removed from the re-graded bluff within their next phase of development. They
have also agreed to perform the grading at their cost starting in the spring of 2005. This
initiative will enable the Municipality to avoid this cost in the future, a potential savings of
$400,000-$500,000.
The re-graded slope will eventually need some means of erosion protection; however,
the work could be deferred until funding is approved. Once the bluff grading is
completed, the Municipality could consider establishing a section of waterfront trail from
Toronto Street to the Region's Plant. Further components of the plan could be added
subject to Council's direction.
Funds for the installation of erosion protection and for the development of the waterfront
park should be included in a future Capital Budget and Forecast.
Attachments:
Attachment 1 - Land Ownership
Attachment 2 - Conceptual Waterfront Plan Phase I
Attachment 3 - Conceptual Waterfront Plan Phase II
Attachment 4 - Armour Stone Revetment
Attachment 5 - Detached Breakwaters
Attachment 6 - Artificial Headlands
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DRAWN BY: E.L.
DATE: April 18, 2005
REPORT EGD-14-05
ATTACHMENT NO.1
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of nearshore profile:
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Eventual
undermining
Future Undermining of Structure Due to Downcutting
REPORT No. EGD-14-05
ATTACHMENT No.4
Plan View
Existing Profile
Bf~<1ch Fill
Detached Breitkwater 1
Cross-Section A-A
Alternative Detached Breakwaters
Detached Breakwaters
REPORT No. EGD-14-05
ATTACHMENT No.5
Artificial Headlands
bl~in8Shufdjnp
Artificial Headlands
Lake Forest, Illinois
Eastern Beaches, Toronto
REPORT No. EGD-14-05
ATTACHMENT No.6