2001-031 - Laserfiche WebLink

Home Browse Search

L7 F—I ® Scope of Work Page 6 Diver -towed video transects (four shore -perpendicular transects per Sector, and one parallel transect per Sector at the equilibrium toe of fill to document toe of fill adjustment) will be proposed. Likely intervals for the video series are at six months prior to construction and at six and eighteen months after project construction. A twelve-month post -construction event may additionally be proposed with the understanding that such an event might be difficult to accomplish with winter sea states and water column visibility. Physical Monitoring Plans for each sector will be prepared and subjected to the same review and comment procedures as those indicated above. Each individual Plan will propose beach profile interval spacing and time series surveys for each of the beach fill segments and adjacent shorelines and the sedimentation monitoring site(s) locations along transects adjacent to each beach nourishment area. Analysis of profile data, utilizing average end -area techniques, will enable ATM to document beach fill performance by determining sand volume changes over time. Task 1.A.10 Determine Revised Composite Grain Size Characteristics in North and South Borrow Areas Owing to modifications to the north and central borrow areas associated with optimal sand quality and fiber optic cable obstructions, respectively, the bounded areas will require modified geometric configurations which will influence the composite mean grain size. Alternative cut configurations will be established for the north borrow area pending analysis of ten additional vibracores that were acquired in late October 2000. Due to the uncertainty of material suitability and usable sand quantities in the north borrow area, it is recommended that the south borrow area be reconfigured to allow for adequate (dredge pass) line lengths to optimize material excavation. This latter effort will assume that insufficient material volumes exist in the north borrow area, thereby requiring cuts from the south borrow area to be utilized to construct the Sectors 1 and 2 initial beach restoration project. Two magnetic anomaly clusters in the south borrow area will require a radial buffer, plus side -slope sloughing allowances, thereby dictating a reconfiguration of the cut boundaries and, hence, the composite grain size characteristics. The procedure for the work will be to refine the plan view (horizontal) boundary of proposed cut, and to compute a revised composite mean grain size (and material statistics) data sheet for each respective borrow area/sub-area as appropriate. This will be accomplished by computation of horizontal and vertical areas of influence of individual cores on the overall sites. The Terramodel software package will be utilized to expedite this effort. Mechanical composite sand samples will be extracted from the archived cores in the central, south and (if deemed acceptable) north borrow areas. This center channel sample extraction will be performed on only a sampling of those cores that serve to 'represent' the horizontal and vertical cut boundaries established in the further development of each of the three borrow areas. Each of the extracted samples will be subjected to grain size distribution, percent silt/clay content, and percent calcium carbonate content analyses. For budgeting purposes, it is assumed that a total of six samples will be extracted from the north borrow area, seven samples will be extracted from the central borrow area, and twelve samples from the south borrow area, for a total of twenty-five mechanical composites. The 'representative' sample locations (from O IWNOOWS\7EMPVRC setas 12 7 Add4-IW S-- 01-1600 da11r12A1