2006-285 - Laserfiche WebLink

Home Browse Search

requests by Indian River County to use this additional artificial reef as mitigation for additional impacts to hardbottom communities, provided that it has not already received mitigation credit for other impacts. Therefore, this additional, LRLC reef will be monitored in conjunction with the mitigation reef to evaluate its performance as replacement habitat for impacted benthic communities and fish populations. Monitoring Schedule A total of three annual monitoring events will be conducted (through Year 3 in 2008) during the summer months (May 1 through September 30). The first annual monitoring event of the mitigation artificial reef (Year 1 ) will be conducted during August/September 2006, approximately one year after completion of artificial reef construction. Mitigation Reef Maintenance During each annual monitoring event, DGPS positioning of the perimeter of the reef will be verified and recorded, and measurements of vertical relief will be performed at a minimum of sixteen perimeter points by measuring the distance from the top of the reef to the base of the reef (sand). A shore-parallel digital video transect shall be performed along the length of the artificial reef for documentation of reef structure, sand spaces, and compliance with boulder specifications . Annual inspections will continue for the life of the beach fill project to verify that the required acreage and vertical relief has been maintained. If the inspection reveals that the acreage or typical relief of the reef has been significantly reduced by subsidence, scour or sand accretion, additional materials will be added as necessary to restore the reef to the as-built design. Permanent Cross-Shore Transects: Video and Still Photographic Documentation Six, 20-meter long cross-shore transects shall be located on the mitigation artificial reef. Three transects shall be located on the high-relief artificial reef structure and three shall be located on the low-relief structure (one on the low-relief module constructed as mitigation, and two on the additional low-relief reef immediately south of the mitigation reef). During the baseline monitoring to be performed during the summer 2006 (Year I monitoring), the transects shall be permanently established using pins to mark each 0 point, 10 meter point, and 20 meter point. The 0 point shall be located on the top (i.e. crest) of the boulder along the nearshore reef edge on the horizontal surface. The pins shall extend a minimum of 20 cm above the hardbottom surface. DGPS positioning will be obtained for each 0 mark, 10 meter mark, and 20 meter mark for each transect. The 20-meter transects shall be sampled using digital video in progressive scan mode. The diver shall swim at a speed of approximately 20 meters/6 minutes (-3 . 5 meters/minute) with a constant camera distance of 25 cm above bottom during the portions of the transect to be quantitatively analyzed. The video transects shall be 2