The Herbert Hoover Dike serves an important role for the entire South Florida region, aiding in flood control, water conservation, and preventing saltwater intrusion into the freshwater lakes. Without the dike, the entire eco-system would be affected and the region would suffer major devastation with even the smallest storm.
The need for a dike was recognized over 100 years ago, but the original structures of sand and muck failed. While ingenious for its time, the weak structure was completely ruined only 15 years later by a hurricane that took thousands of lives. It was later re-built in the 1930’s but still did not meet standards to truly address flood prevention. It wasn’t until the 1960’s that the new dike system you see today was constructed and given the name, the Herbert Hoover Dike.
The 143-mile earthen dam surrounds Lake Okeechobee and prevents flooding throughout the South Florida area, including the eco-important Everglades. Improvements have been made, levees have been added, but years of erosion and aging have damaged the over 50 year old structure. With the Dike’s stability at risk, the US Army Corps of Engineers (USACE) continues to invest in research to determine the best options for repair.
Under Atlantic’s prime contract with the USACE Jacksonville District, we are honored to assist in improving and re-building this essential barrier for the South Florida region. Atlantic was tasked to complete a complex survey project, involving a 25 mile area around the dike because we can complete a wide variety of survey requirements. The USACE Jacksonville District required three types of survey to be performed – boundary, topographic, and bathymetric surveys.
Topographic Survey
The topographic survey was collected at 100’ intervals, coincident with the stationing provided along the existing dikes. Collection points were required to be perpendicular to the provided HHD alignment at a rate of 10Hz with a maximum of 12.5’ spacing between sorted points. Using 3 NGS control monuments, Atlantic established temporary benchmarks throughout the project site consisting of #5 rebar capped and stamped for identification. Vertical and horizontal coordinates were established using first order GPS static observations. The temporary benchmarks and NGS control monuments were used as check-in points to maintain accuracy during the project, as the GPS satellites change constellations throughout the day. After creating the topographic profile using a combination of VRS and RTK, Atlantic then collected cross sections of the dike itself. Some areas of the project site were not suitable for running conventional profiles so in order to maintain a continuous Digital Terrain Model (DTM), our team of surveyors collected individual topographic points within these areas.
Boundary Survey
A boundary survey was required to recover/establish the right-of-way of the Herbert Hoover Dike. Atlantic completed deed research using a combination of online sources and actual property records at the Glades County Courthouse. The property legal descriptions were necessary to define the rights-of-way. Atlantic performed property corner reconnaissance on over 100 individual properties that shared a boundary with this section of the dike. Atlantic then created a MicroStation Inroads compatible DRM file of the canal and an ASCll file of all points collected and DTM points. From the data collected, Atlantic also created a comprehensive DGN file of the recovered boundary line to indicate, encroachments, recovered monumentation, adjacent parcel numbers and set monumentation.
Bathymetric Survey
As an extension to the topographic survey, Atlantic also performed a bathymetric survey on this same area to establish sub-surface profiles of the adjacent dikes. Our team used multi-beam sonar to collect cross sections across the existing canals beginning at the dike side edge of water to the landside edge of water. Each cross section was designed to be perpendicular to the provided HHD alignment profile at every 100’ station interval. High and low frequencies were used to record top of the silt level and the harder canal floor beneath the silt level.
Final Products
After completing the Task Order, Atlantic processed all of the topographic data and established the individual cross sections required for both the topographic and bathymetric surveys. The final processed survey data were compiled and delivered in comprehensive DTM and DGN files. As with any survey project, the last deliverable was a comprehensive Survey Report which detailed our methodologies for collection and processing as well as the final coordinate values for all surveys.