There is a section of land from where the Belongil Creek meets the sand to around 160m south of the public beach access which is subject to erosion.

Over a distance of 20 to 30m north of the end of the existing protection works there has been a loss of approximately 10 metres of land, with a resulting loss of the original old dune profile, over the period December 2018 to November 2022.

This has impacted on the beach. It has also impacted on public safety, on beach amenity, on the Elements of Byron resort and on access to the beach from within the Elements of Byron resort.

The erosion on this section of land (which includes Elements of Byron resort land, Crown land and land owned by Byron Shire Council) is caused by a chain of events which, while they involve natural processes, are also affected by human intervention.

We are proposing, having regard to the 2016 Coastal Management Act, a 40 lineal metre extension of the existing soft coastal protection works. The life of the proposed works is five years.

Due the specific nature and design of the soft proposed works any increased erosion as a result of these works is expected to be limited.

However, to meet the requirements of the Coastal Management Act 2016, it is our recommendation that conditions be imposed on any consent for the restoration of the beach, or land adjacent to the beach, if any increased erosion of the beach or land adjacent to the beach is caused by the presence of the works, for the life of these works.

The application will be assessed by Byron Shire Council and determined by the Regional Planning Panel (RPP).

It is anticipated that the work would take no longer than four weeks to complete. Public beach access would not be hindered during this time. The works would be carried out during normal construction working hours Monday to Friday. No work would be undertaken on weekends or public holidays. Approval may be sought to extend working hours during Monday to Friday to take advantage of tide levels and weather conditions to reduce the construction period.

No. The public beach access is located approximately 160m to the north of the northern limit of the proposed works.

All the proposed works would be located on private land owned by North Byron Beach Resort. Temporary limited access on the seaward side of the proposed works would be required during construction.

North Byron Beach Resort.

At the completion of the works, vegetation of the dune areas would be undertaken using suitable species.

No. The proposed works would protect only the area directly behind the works. The C4 land is north of the public beach access and the public beach access is 160 metres north of these proposed works.

The extract below is from the 2023 Coastal Engineering Assessment by Royal HaskoningDHV.

Firstly, it is necessary to consider whether any increased erosion of the beach or adjacent land would be caused by the presence of the works. This can be considered under several topics:

Additional scour/erosion immediately seaward of the works;

End effects on immediately adjacent land; and

Consequences due to ‘locking up’ of sand behind the coastal protection works.

Additional scour/erosion immediately seaward of the works

Research has shown that concerns that seawalls cause additional scour/erosion immediately seaward and greatly delay post-storm beach recovery are probably false, as there are no known data or physical arguments to support these concerns (US Army Corps of Engineers, Coastal Engineering Manual (CEM), pp V-3-28, V-3-32).

Accordingly, the proposed works would not be expected to cause any increased scour/erosion immediately seaward of the works, noting also that at times of severe storms the erosion escarpment within the dune system can be near-vertical and thus steeper than the geobag works.

Furthermore, the low crest height of the proposed works (approximately 2.1m AHD) would limit any reflective behaviour.

End effects on immediately adjacent land

Increased erosion of immediately adjacent land, particularly to the north of the works, is predicted to occur due to end effects, caused by the presence of the works. An underlying assumption for assessing the extent of the end effect is that the volume of sand ‘locked up’ behind the coastal protection works and which would otherwise be available to meet the storm erosion demand is offset within the end effects.

As noted earlier, the extent of the end effect due to the proposed works is not expected to reach the public accessway located some 160m north of the northern limit of the works over the life of the works of 5 years, however there is some uncertainty in this prediction.

Since some increased erosion would be caused by the presence of the works, to meet the requirements of the Coastal Management Act 2016, satisfactory arrangements would need to be made (by conditions imposed on the consent) for restoration of the increased erosion for the life of the works.

It is recommended such a condition is imposed.

Consequences due to ‘locking up’ of sand

There are two potential consequences of ‘locking up’ sand behind the coastal protection works:

• Additional localised erosion to meet storm erosion demand. This has been considered in the above discussion of end effects.
• Impact on long term shoreline recession.

An assessment of the second point has been made by considering the volume of sand that could be potentially ‘locked up’ behind the coastal protection works as the shoreline recedes.

Based on RHDHV (2019) it is considered reasonable to adopt a long term average shoreline recession rate due to net sediment loss (underlying recession) of 0.5m/yr and a shoreline recession due to sea level rise over the next 5 years of 1.8m (0.008m/yr x 5 years x 45 [Bruun Factor]). This would give a total shoreline recession over the next 5 years of 4.3m.

If the proposed works, with a crest level of approximately 2.1m AHD, restricted the entire active height of the dune of 7m from recession, the volume of sand ‘locked up’ over 40m for 5 years would be approximately 1,200m³. If, on the other hand, the proposed works only locked up the sand to a height equivalent to the crest level of the works, on the basis that the dune above the crest level would be able to recede, the volume of sand ‘locked up’ over 40m for 5 years would be approximately 400m³.

The volume of 1,200m³ is considered an overly conservative estimate. However, in order to introduce some level of conservation it is considered that an average of the above two estimates, or approximately 800m³, could be adopted.

As it happens, in order to re-establish the dune profile on the private land, it is proposed to import approximately 800m³ of sand to site for this purpose. This would account for the adopted estimate of the ‘locked-up’ volume of sand for 5 years.

There is also the recommendation, as noted above, that a condition of consent be imposed to address Section 27 (1)(b)(ii) of the Coastal Management Act 2016.

Hence it is considered that satisfactory arrangements have been made.

The proposed works would include the regrading of the existing steep erosion escarpments which are potentially unstable and pose some risk to life and public safety:

This action would have a positive impact on risk to life and public safety. The proposed works have been designed in accordance with accepted coastal engineering practice and design guidelines to maximise stability. They would be subject to monitoring and maintenance in the event of any damage.

The works proposed now do not address the loss of the littoral rainforest and are not long term. However, given the uncompleted Coastal Management Plan we believe this is the best option for now.

A longer term strategy has been considered for the entrance area of the Belongil Estuary. The strategy outlined below would be permanent, would not impact on neighbouring properties (in the unlikely event of any impact occurring conditions of approval would include repair at the expense of North Byron Beach Resort) and all works would be funded by North Byron Beach Resort. These works are not, however, the subject of this application.

The extract below is from Section 5.4.2 of the 2023 Coastal Engineering Assessment by Royal HaskoningDHV.

5.4.2 Longer term management options at the entrance to the Belongil Estuary

The current Belongil Creek Entrance Opening Strategy (Final report (Revision 1), December 2021) acknowledged that as the spit elongates more to the north and Littoral Rainforest is further eroded, some management response in the entrance area is warranted, noting that the bank retreat in the area is currently occurring at the rate of 3 to 5 m/yr.

In terms of a management response, it was stated that a tripper wall or some shorter, shore normal buried groynes, beach scraping and protective works, could help protect the Littoral Rainforest community and the Elements of Byron foreshore (Final Report (Revision 1), December 2021, Section 4.4). The Final Report went on to say that the necessary planning and investigations for the above options should begin now (late 2021) under the NSW Coastal Management Framework, ie as part of the development of a CMP covering the Belongil Estuary.

RHDHV had also earlier in 2015 considered management responses in the entrance area of Belongil Estuary to address erosion of the Littoral Rainforest and Elements of Byron foreshore. The preferred management response comprised of a number of main elements:

a southern spur wall, having the primary aim of training the outlet position of the Belongil Estuary (a form of tripper wall);

a northern spur wall, aimed at mitigating the risk of the entrance breakout channel returning (meandering) toward the resort foreshore immediately north of the southern spur wall;

retention of the existing geobag coastal protection works;

periodic beach scraping in response to beach conditions; and

estuary foreshore protection works along the left hand bank (looking downstream) extending upstream from the southern spur wall to prevent further erosion of the Littoral Rainforest and outflanking landward of the southern spur wall.

The southern and northern spur walls were proposed to comprise sand filled containers, either mega containers or 2.5m3 geocontainers.

The RHDHV proposal including a concept design plan and sections was set out in advice to the then North Byron Beach Resort and could be a consideration in the development of a CMP covering Belongil Estuary.