7/16/1991 - Laserfiche WebLink

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r SOL 6 1391 1 BOOK C) PAVE * A copy of the survey drawing is on file in the Board of County Commissioners Office. On the date of the survey, tides were approximately 0.5' above previous survey dates. • on three dates when surveys were conducted, the tide range was approximately 0.61. The County's contract required that a 5.0' elevation (NGVD 1929 datum) channel be constructed -with a 0.5' tolerance allowed. The channel was to have a 30' - 40' bottom width and 2:1 -side slopes. The channel as currently existing has a low water depth of approximately 3.2' at top of silt and 5.0' at hard bottom and a high water, depth of 4.0' at top of silt and 5.8' at hard bottom. Prior to dredging, the water depth was 0.2' to 0.9'. As currently dredged, the channel is navigable. There appears to be a layer of silt approximately 1.8' deep between elevation 3.5' and 5.01. The silt is a soft consistency that will not support the weight of an average person. It is possible that pre -dredging surveys did not adequately define the entire silt layer and that much of the silt is in suspension near the bottom of the canal. It is probable that agitation from the suction dredge placed this fine silt material in suspension during the dredging operation and after dredging, it began to settle. During the dredging, the contractor had difficulty getting the dredge into the project area and he dredged portions of the channel west of Station 11 to reach site #2'at the mouth- of the canal. ALTERNATIVES AND ANALYSIS The County Attorney and Public Works staff has reviewed the contract language and we are of the opinion that the County staff did accept the project as complete in November, 1990. The one-year warranty provision in the contract specifically pertains to "mechanical and physical defects, breakage, and other damages and failure, under normal operation". This warranty clause pertains to'mechanical'equipment or structures, and is a standard condition in all Public Work project contracts. The Attorney's Office and Public Works staff do not interpret -this paragraph as a one-year guarantee that a dredged area remain at a certain depth for a one-year period. Staff did inspect the work in October and November, 1990, and certified that work was complete at that time. Permit Status Both the U.S. Army Corps of Engineers Permit and Florida D.E.R. Permits are active permits and if additional dredging is desired, new permits at this time are not required. RECOMMENDATIONS Staff is of the opinion that the canal and that portion of the Indian River within the project limits has been dredged sufficiently to allow navigation of small craft that can navigate beneath the Indian River Boulevard Bridge. Prior to dredging, the.Te was almost no water depth at the mouth of the canal (0.01 to -0.2' elevation). If additional dredging is requested, no additional permits are required. Staff would suggest that the installation of 6 or 8 daybeacons (estimated cost $4,800 - $6,400) to mark the existing channel would be a preferable option. 22 M