Goderich considering shoreline hardening project

With the risk of erosion impacting properties and natural habitats, a feasibility study was conducted by BM Ross for a shoreline hardening project.

Bluff erosion is a natural process and is essential for the maintenance of sand baches.

The nearshore waters of Lake Huron provide ecological services to aquatic and terrestrial life.

Recent analysis shows the average annual recession rate of the bluff in the subject area is 0.69 metres per year.

Stephen Jackson of BM Ross discussed results of the feasibility study at the February 3 meeting.

“Council had tasked us with looking at the feasibility of hardening the remaining portion of the Goderich shoreline that isn’t hardened,” explained Jackson.

The study area is south of Rotary Cove and south of the former dog run pathway.

A proposed shoreline protection project could involve the installation of an armour stone revetment at the toe of the slope.

The conceptual design for the armour at that site is like the armour currently at the shoreline.

Over the years, to mitigate damage from rising lake levels and destructive waves during certain seasons, groyne installations along the shoreline were introduced as part of bluff stabilization and beach nourishment projects since the 1980s.

More recently, rock groynes and armour stone revetments were installed along the shoreline between the Goderich harbour and the project study area.

Additionally, a portion of the study area’s bluff was graded by the Coast subdivision’s developer.

If approval for armouring goes forward, a comprehensive coastal study will be required to ensure the structure will not negatively impact the slope, adjacent properties or the shoreline processes.

BM Ross stated in the report that the installation of an armour stone revetment would prevent natural erosion in this location and impact the sediment contribution downdrift. To compensate the lost of input of sediment, beach nourishment would be needed on an annual basis.

Monitoring will be required as well, to ensure that fish utilize the surrounding habitats.

The recent feasibility study was made in consultation with the Department of Fisheries and Oceans Canada (DFO), Maitland Valley Conservation Authority (MVCA), Ministry of Natural Resources (MNR), Saugeen Ojibway Nation (SON), and Chippewas of Kettle and Stony Point First Nation.

In the DFO response, they stated they can likely approve shoreline hardening provided there is adequate compensation for lost fish habitat.

MVCA was not supportive of armour stone revetment, unless a comprehensive coastal study was completed that demonstrates there no negative impacts to adjacent properties or shoreline processes.

MVCA was supportive of a feeder beach, rather than revetment.

A feeder bluff is an eroding coastal bluff that delivers sand and gravel to a beach over time. Feeder bluffs contribute to the amount of sediment on the beach below. Most bluffs erode to some extent and are likely to provide sediment to the coastal environment.

A feeder beach is an artificially widened beach that serves to nourish downdrift beaches. A feeder beach is created by depositing dredged material near the toe of the slope.

“A feeder beach is taking materials, such as dredge materials that are designated to disposal sites, taking that natural sediment that would otherwise be disposed of and placed at the toe of the slope,” explained Jackson.

“The amount of material at the toe of bluff is going to highly depend on lake levels, and variability and the timing between high and low lake levels.”

When talking to the ministry, MNR highlighted that before they can permit anything there has to be adequate Indigenous consultation.

MNR had many examples of shoreline hardening projects across Ontario but were more supportive of natural solutions such as the feeder beach suggested by MVCA.

When speaking with SON they are opposed to any shoreline armouring and are supportive of a feeder beach as well.

SON highlighted that any work in that area would require archeology on the bluff and in the shallow water, and fish sampling would need to be completed before, during and after the project.

Chippewas of Kettle and Stony Point First Nation didn’t have any initial feedback, other than wishing to remain consulted as process continued.

According to Jackson, BM Ross completed technical work that included a natural habitat assessment and sampling dredge material to see its suitability for the feeder beach option suggested by MVCA.

According to Jackson the habitat assessment found limited quality fish habitat present at the study area.

“It’s somewhat of an advantage to do any work there. The higher quality fish that would be there would mean a higher quality compensation that would need to be made,” explained Jackson.

Results from the dredged material exposed grainsize suitable for a feeder beach, as well as suitable chemical composition.

“It is the most ideal grain size to use for a feeder beach,” added Jackson.

“It would meet all the tests required by provincial regulations to be used as a feeder beach.”

With the option of a feeder beach, there would be no shoreline protection, but this option would involve depositing a combination of sand, gravel, and cobble at the north extent of the area to enrich the nearshore environment.

Conceptually, material could be sourced from Goderich harbour and marina dredges, as this material is currently deposited offshore or hauled and disposed of inland.

According to MVCA, the feeder beach would be a novel approach to addressing shoreline erosion.

A feeder beach has potential to restore and enhance habitat int eh nearshore environment by increasing shoreline complexity.

According to the report, coarser material could result in the development of spawning beds, reefs and areas of refuge. Sand and smaller course material could result in development of spawning grounds, shelter and food sources for fish and contribute to improved water quality and nutrient cycling.

Furthermore, the deposited material would buffer the shoreline from wave action, which may result in growth of aquatic vegetation in the nearshore environment, increasing productivity of the ecosystem.

In the report from BM Ross to Goderich Council, three options were presented.

One – Do nothing. No trigger was identified that obligates Goderich to complete work at the toe of the bluff.

“Through our investigation we didn’t trigger anything that obligated Goderich to complete the work at the toe of the bluff,” Jackson explained.

“That was expected that area would erode.”

Two – Initiate Municipal Class Environmental Assessment (Schedule C) to further pursue shoreline hardening.

Three – Defer further decisions until MVCA’s sediment by-pass modeling is complete.

In addition to the options, cost involved must be factored before a decision is made. Further studies would be needed for options two and three, including an archeological study at the cost of $40-50,000, and a fish sampling study for one nearshore season at the cost of $5-7,000.

“Regardless of whether you’re looking at armouring or a sediment by-pass, if you’re looking at doing something the next studies on the table would be archeology as well as the fish sampling,” explained Jackson.

Based on consultations, approval could be obtained for armouring the shoreline if impacts to fish habitat are appropriately mitigated, and it is proven the work will not impact downdrift erosion.

Additionally, modelling will be undertaken to determine if a feeder beach using sediment and other sources has the potential to reduce erosion rates and enhance nearshore habitat.

According to Chief Administrative Officer (CAO) Janice Hallahan, after speaking with MVCA, it could take two to four years before technical work has been completed on further studies.

Council deferred a decision on a shoreline hardening project until the sediment by-pass modelling is completed by MVCA.