2007-225 - Laserfiche WebLink

Home Browse Search

Indian River County Sector 3 - Beach Restoration Project Additional Services Scope of Work measurements of sediment thickness will be performed within each quadrat using a ruler to measure to the nearest cm. Continuous layers of sediment less than 1 cm covering the hardbottom surface and benthos shall be recorded. Sediment accumulation measurements shall also be recorded at each rod/eyebolt along the transect and at 1 -meter west of each rod/eyebolt using a ruler to measure to the nearest cm. If a ledge exists at the nearshore hardbottom edge (0-mark) or subsequent exposed hardbottom ridges , sediment accumulation shall be estimated by measuring the distance from the pin on the crest of the ledge to the foot of the ledge (sand) . Task 2c : Nearshore Hardbottom Edge Mapping: In concert with the fieldwork under Task 2a, CSA INTERNATIONAL shall map the nearshore hardbottom edge within the Study Area. The method for mapping shall be dependent upon underwater visibility conditions. The preferred method is by diver swimming the hardbottom edge with a DGPS antenna. Upon completion of the diver-mapped hardbottom edge, a towed-diver system with DGPS -integrated video may be utilized to document the conditions and benthic communities along the nearshore hardbottom edge if water depths and underwater visibility allow safe boat operation and safe diving conditions . If visibility conditions do not allow for a diver-mapped hard bottom interface the County shall coordinate with the Department for approval to utilize alternative methods for mapping the nearshore hard bottom edge, which may include the collection of 20-meter shore- parallel video transects at 150-m (500 ft) intervals with DGPS positioning of the hard bottom edge/video transect locations, ten measurements of vertical relief of the nearshore hard bottom edge along each transect, video documentation of the dominant benthos, and identification and canopy height measurements of the two dominant macroalgal species along each transect (five measurements per species) . Task 2d - Transect Analysis: Following completion of the fieldwork under Tasks 2a through 2c, CSA INTERNATIONAL shall perform analysis of transects as described below: Two, 20-meter long segments of the video transect shall be quantitatively analyzed using PointCount' 99 or a comparable software package based upon the random point count method for estimation of percent cover from digitally frame-grabbed underwater video images . The first 20-meter segment shall correspond to the First 20 meters of hardbottom (commence at the 0 point at the exposed nearshore hardbottom edge and continue to the 20-meter mark). The second 20-meter segment shall cross hardbottom between 40 and 80 meters along each transect. The exact location of the second 20-meter segment shall be determined at the time of transect establishment based upon the benthic landscape and location of hardbottom ridges along the transect, and shall be referenced to the nearest pin along the transect for repeated occupation of the same stretch of transect for video analysis. DGPS positioning will be obtained for the start point of the second 20-meter segment along each transect. Each 20-meter segment shall result in approximately 100 non-overlapping frame-grabbed images . A unique set of 20 random points shall be generated at the time of frame- grabbing and stored with each set of images so that the same points are assessed during Page S of 14 June ] 3, 2007