Technical Technical Cost Design Life Amenity Key Risks Environment/ Further work Effectiveness Effectiveness in Effects on Required (Design, the longer term Intertidal Reef construct, (Design, analysis Communities in (changing maintain) monitoring) PPH MNP climate) Shorter Large Timber is Timber is less Increased Increased Smaller Detailed design compartments improvement cheaper than durable and not number of number of beach structure. Piling of timber improves beach through rock. a strong as rock. smaller groyne structures. into beach. Small groynes holding capacity, Compartment 3; Improved structures on to moderate Smaller Timber Site Survey though timer Little to no alignment will the beach will change to region structures. Less structures create structure unable effect in reduce repeat alter sediment material. vertical drop-off to extend as far Compartments 1 wave impact connectivity. transport. between Works largely on offshore and 2 structure. compartments shore. Notable increase Climbing, trip Timber/Polymer Approximately in Compartment hazards. – 3. Little change $3500/m of structure elsewhere. Average beach width increase - groynes Compartment 1: 0 m Compartment 2: 0 m Compartment 3: Up to +10 m additional Timber structure should be Add designed on an – orientation that aligns with average wave direction Option RANKING BELOW BELOW ABOVE MODERATE MODERATE MODERATE MODERATE MODERATE AVERAGE AVERAGE AVERAGE
Technical Effectiveness Technical Effectiveness in the longer term (changing climate) Cost (Design, construct, maintain) Design Life Amenity Key Risks Environment/ Effects on Intertidal Reef Communities in PPH MNP Further work Required (Design, analysis monitoring) Option – Add additional groynes – Timber/Polymer Shorter compartments improves beach holding capacity, though timer structure unable to extend as far offshore Notable increase in Compartment 3. Little change elsewhere. Average beach width increase - Large improvement through Compartment 3; Little to no effect in Compartments 1 and 2 Timber is cheaper than rock. Smaller structures. Less material. Works largely on shore. Approximately $3500/m of structure Timber is less durable and not a strong as rock. Improved alignment will reduce repeat wave impact structure. Increased number of smaller groyne structures on the beach will alter connectivity. Increased number of beach structures. Timber structures create vertical drop-off between compartments Climbing, trip hazards. Smaller structure. Piling into beach. Small to moderate change to region sediment transport. Detailed design of timber groynes Site Survey Compartment 1: 0 m Compartment 2: 0 m Compartment 3: Up to +10 m Timber structure should be designed on an orientation that aligns with average wave direction RANKING MODERATE MODERATE BELOW AVERAGE BELOW AVERAGE MODERATE MODERATE MODERATE ABOVE AVERAGE
Point_Lonsdale_Groyne_investigation_-_FINAL_REPORT.docx