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) Shortened Large Rock is Rock is long More groyne Increased Large rocks on Detailed design compartments Improvement expensive lasting and structures on number of beach rock flats. of timber improves beach across entire material. structure will the beach will structures. groynes Moderate holding capacity beach front Approximately last with site alter change to region Site Survey $5000/m of specific design. connectivity. Large sediment Improved width structure across entire Improvement If kept on same transport. study area. across entire Works will be alignment as More large Construction beach front with onshore and existing groynes, Average beach groyne efforts within more spread and offshore. experiencing width increase - structures Marine National symmetrical higher wave extending Park. Compartment 1: compartments loads. Advise offshore. Up to +25 m angling structure Works onshore Compartment 2: more in to and offshore Up to +30 m average wave Compartment 3: direction Up to +30 m Advise that structure is designed on an orientation that aligns with average wave direction. RANKING ABOVE ABOVE VERY HIGH HIGH VERY HIGH VERY HIGH VERY HIGH HIGH 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) Shortened compartments improves beach holding capacity Large Improvement across entire beach front Large Improvement across entire beach front with more spread and symmetrical compartments Rock is expensive material. Approximately $5000/m of structure Works will be onshore and offshore. Rock is long lasting and structure will last with site specific design. If kept on same alignment as existing groynes, experiencing higher wave loads. Advise angling structure more in to average wave direction More groyne structures on the beach will alter connectivity. More large groyne structures extending offshore. Increased number of beach structures. Large rocks on rock flats. Moderate change to region sediment transport. Construction efforts within Marine National Park. Works onshore and offshore Detailed design of timber groynes Site Survey Improved width across entire study area. Average beach width increase - Compartment 1: Up to +25 m Compartment 2: Up to +30 m Compartment 3: Up to +30 m Advise that structure is designed on an orientation that aligns with average wave direction. RANKING VERY HIGH HIGH VERY HIGH VERY HIGH VERY HIGH ABOVE AVERAGE ABOVE AVERAGE HIGH
Point_Lonsdale_Groyne_investigation_-_FINAL_REPORT.docx