Indian River Summary & Conclusions

• ATM reported that approximately 589,350 cy compatible sand was excavated and placed in the project area. But only about 405,400 cy (351,800 cy above MHW and 53,600 cy between MHW and DOC) was measured immediate post-construction (6/03) (ATM, 2005).
  
  Rather than calculating volume change to DOC at -16 feet, the BSRC calculated the filled volume to the landward edge of the hard bottom field. The results were 540,000 cy for the immediate post-construction and 422,204 cy for the 12-months post-construction.
  
  
• Both ATM and the BSRC showed that the volume changes above MHW were approximately 352,000 cy for the immediate post-construction and about 283,000 cy for the 12-months post-construction. The beach fill remaining between MHW and landward edge of hard bottom field was estimated as about 188,000 cy for the immediate post-construction and about 139,200 cy for the 12-months post-construction. As a result, the beach fill spread in the rock fill and/or either sides of the project area would be about 49,350 cy immediate post-construction and 167,150 cy 12-months post-construction.
  
  
• One month after the 12-month post-construction survey, the project area was first hit by Hurricane Frances on September 5 and then by Hurricane Jeanne on September 26. As a result, the fill sand remaining after the two storms was about 230,400 cy or 39 % of the original fill volume to the landward edge of the hard bottom field.
  
  In addition to the fill sand loss mentioned above, two third of the project area suffered dune erosion landward of the pre-construction locations due to the two storms in September 2004. An estimate of approximately 67,000 cy was eroded from the pre-construction profiles.
  
  
• Comparable surveys in the offshore hard bottom area do not provide a reliable volume change estimate as is the case for an offshore sand bottom. It was clear that the offshore survey data in the rock area for this project actually represented the elevations of rock instead of the filled sand. As a result, the filled sand which was spread around the rocks was difficult to be measured accurately during the surveys. As a result, the volume change between the MHW and the DOC which included the hard bottom area in the report was very questionable.
  
  
• For the July 2006 survey, the near-shore area was not surveyed, only the onshore and offshore data was collected.  Shoreline change and volume change above MHW were calculated for this survey, however, total volume change could not be computed.