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pfprf Vf+l4ff Page 4 These findings will be presented to the County prior to proceeding with side scan sonar field invesiigaiions of the identified borrow areas. Task 1.7 Obtain Vibracores in Tareet Areas The number of cores will be optimized based on distance from shore, planform 40 geometry of the candidate site(s), water depth, anticipated core lengths necessary for logging, sampling and archival, and apparent material composition. It is assumed that vibracores will bu collected during 7 field days and that 48 to 52 vibracores will be 0 recovered. It is estimated that, for the purposes of this study, a reconnaissance -tenet spacing will initially be utilized in the areas of potential sand deposition. Should the field acquisition of vibracores reveal consistently high quality (and in -field estimates of quantity) material in one or more of the candidate sites, efforts will be intensified in those areas to reduce the grid coverage area and, in effect, produce a ptans-and- sperificalions-Invel riistributlon of vibracorRs. Constnrction plans and specifications - level vibracores should be acquired on an approximately 1,000 ft grid completely covering the area of anticipated sand excavation. A conservative estimate of five to eight 20 -foot vibracores per field day is assumed over the course of the single mobilization effort. The vibracoring effort entails positioning a Coast Guard certified coring vessel over a previously determined (or Engineer -directed) coordinate set offshore. Once in position, the coring system utilizes a pneumatic impacting piston mounted on the torp of a core barrel constructed of steel or aluminum pipe and fittest with an internal plastic liner to contain the sediment core sample The core barrel is mounted on a stable platform and serves additionally as a guide to the vi"or and care barrel The conrtg system is deployed to the ocean bottom and relneved utilrzrng a deck -mounted hydraulic crane. D(3PS positioning of the core sample retrieved is recorded along with record of the barrel penetration into the seabed The procedure is then repeated followng removal of the plastic liner from the barrel and visual inspection of the material contained within the liner 'Task 1 8 Nrform l Wp i'a mig atilt Arra.�YSi of _F1t u r Core LIM) acquisition, the vibracores will be split, visually inspected, and kXpged in detail in accordance with USACE standards Results of the kMing will be reported on USACE Engineering Form 1836 and will additionally be recorded on GTLoe geotechivical logging software. This geotechnical logging software rs part of ATM'% library of in-house software Textural classification during core loNing will be prepared in accordance with the Unrf`ed Soils Classification System, described In ASTM Standard D-2487 Color photographs of the sectioned core will be taken at 11 -foot intervals Samplers taken at 2 -foot intervals (closer if warranted by changes in hlhology) and composite samples will be analyzed for grain size, percent mud and gravel. Grain size analysis will adhere to As I M standard 17-422 for mechanical particle size analysis of the soils. Should the samples warrant, carbonate and organic content procedures can be employed as well Analyses will be conducted by mechanical sieving utilizing a set of nested screens dividing sediments at 'J� phi intervals from -4 to +3.a ,phi, with the +3.75 phi (#200 mesh screen). Laboratory quality assurance procedures dictate that a replicate of approximately 5% of all samples taken for grain size analyses is undertaken. Grain size distribution of samples processed in accordance with the above procedures will be analyzed using the method of moments and graphic methods as described by Folk (1974). Tabular summaries of each sample will be generated and will report sieve size, phi size, mesh opening size in millimeters, weight of sediment retained in grams, cumulative percent retained, and cumulative percent passing. Sample statistics (e,g., mean, standard deviation, skewness and kurtosis) will also be displayed in the summary tables. A frequency plot of grain size distribution will be provided for each sample in accordance with USACE Form 2087. Upon completing the above described materials tests and analyses, the cores will be packaged in suitable containers and transferred to the County for permanent storage at a designated location within the County. W lUmr61rc sop designWged wsliraLSCOPE OF VVORKOA2090elh