Data and Core Recovery and Documentation APTIM (Boca Raton, FL) has previously acquired geophysical and geotechnical data for the GSA relating to this project. The physical cores currently reside with APTIM and the Contractor is responsible for moving these, if applicable, to retain their vertical and horizontal integrity. The GSA may facilitate the transfer of the geophysical data and vibracore. All pre- and post-processed seismic, bathymetry, side-scan, and magnetometer data and physical vibracore will be obtained by GSA and the Contractor. The GSA will also facilitate specifications regarding geophysical and vibracore acquisition in support of metadata development. The geophysical and vibracore data requires Federal Geographic Data Committee (FGDC)- compliant metadata. If applicable, vibracores should be retrieved from APTIM by the Contractor. All vibracore sections are to be split; one half for logging and analyses and one half to be stabilized to maintain sediment’s vertical and horizontal character for shipping and preservation. Vibracore sections for archiving will be wrapped and labeled with core identifier and depth markers, and the Contractor is responsible for their transport to the GSA facility at 420 Hackberry Lane, Tuscaloosa, Alabama 35401. Geographic Information System Data All acquired data should be attached to geographic information system (GIS) point, polyline, and polygon vector thematic layers, as well as geophysical raster data (e.g., side-scan, magnetometer). These layers should reflect data acquisition, post-processed data, and interpretations. Geophysical GIS data should include tracklines, shot points, paleochannels, magnetic anomalies, vibracore, and plane view delineations of sand meeting or close to meeting the criteria previously mentioned. Unsuitable side-scan sonar and magnetometer processed data should be mosaicked. FGDC-compliant documentation is required. Magnetometer Survey In support of the cultural resource assessment, magnetic anomalies should be identified and tabulated with specifications such as position, amplitude, duration, and signature. Post acquisition magnetometer tracklines should be provided with attributes to anomaly points all cross-walked with attributes tying magnetometer tracklines to anomaly nomenclature suitable for a GIS geodatabase format. Tabulated/GIS attributes should include magnetic anomaly ID, characteristics, gamma intensity, duration (feet), coordinates, assessment of significance, recommended anomaly buffer, and relevance to side-scan contact. The magnetometer tracklines and anomaly contacts should be provided and adequately attributed in GIS.
