Lake Manatee Dam


Monitoring projects, whether on buildings, bridges, railways, tunnels, or other structures, require robust surveying tools and a system capable of collecting and analyzing data into something actionable.


Striking this balance was the challenge facing surveyors in Manatee County, Florida, who were tasked with monitoring the Lake Manatee Dam––a structure that has spent the last 50 years under constant pressure.


Ironically, with hydrology unique to central Florida, the same conditions that made the dam feasible on Lake Manatee also threatened the integrity of its spillway walls––the primary means of relief following heavy rains and other high water conditions.


To ensure public safety and reliable access to water, county surveyors set out to monitor these spillways to detect significant shifts in position and prevent potential problems far in advance.


We spoke with Manatee County’s Survey Division Manager, Todd Boyle to learn how transitioning to Berntsen’s smart targets, in combination with a simple Excel spreadsheet for analyzing monitoring data, has made it possible to identify potential integrity issues and how these same tools and systems could be used in other monitoring projects around the world.

 

Replacing a rudimentary monitoring system


Until just a few years ago, the monitoring tools and techniques used on Lake Manatee Dam offered very limited data in only two dimensions: top and bottom. 


Using a long plumb line and heavy weight, crews could get a general idea of whether or not a wall was leaning in toward the spillway area, however, just taking these measurements was a challenge which forced crews into potentially dangerous areas on-site.


This, along with potentially dangerous gaps in monitoring movements in a third dimension prompted a search for something more sophisticated.

 

Smart survey targets as a safer, more actionable monitoring solution


In search of a way to get more actionable data while taking crews out of harm’s way, Todd’s team received approval to move forward with Berntsen’s line of Rothbucher Systems smart targets pictured below.

 

RS60

The RS60 Retro Reflective Survey Targets 


These smaller, more robust surveying targets could be attached permanently for consistent monitoring over long periods of time without the need for constant adjustment in the path of the spillway as marked by the arrows in the photo below.

 

Lake Manatee Spillway Walls

Survey targets placed along the Lake Manatee Dam spillway walls.

 

[Related:] 4 Real-World Uses for Smart Angle Survey Targets & Prisms


Using two nearby control points for reference, 30 targets were installed around the dam and used in conjunction with a Leica MS50 total station to provide three-dimensional monitoring data precise enough to track even the slightest changes in position.

 

Instant results with a simple spreadsheet


To get the most out of the data these targets provided, the team developed an Excel spreadsheet that allowed officials to instantly see changes in position relative to prior measurements, simply by dropping new data sets into the file.


 

Spreadsheet

A screenshot of the monitoring spreadsheet.

 

Once a new data set is generated, figures can be imported into the spreadsheet, which then automatically divides by the number of measurements taken and compares that value to the prior positions.


When a large discrepancy is found, it’s automatically assigned a red color code to indicate a potential problem. Smaller shifts are labeled in yellow, and those within a safe tolerance show up in green.

 

Spreadsheet Close Up

 

As Todd describes, having the ability to immediately identify a potential problem in a system simple enough for anyone to use has been the linchpin of his team’s success.


“It’s amazing that I can bring all of that data into a spreadsheet, and in one second, see if there’s a problem or not.” – Todd Boyle, Manatee County Survey Division Manager


After being forced to scrap prior measurement data due to lost control points following emergency construction in 2014, it only took a few subsequent measurements to clearly see no significant problems developing along the site, confirming to county officials that the structure and those in the area were not in danger.

 

A three-part formula for monitoring success


As Todd explained, the keys to an effective monitoring project require three primary components:


1.     Precise, reliable surveying equipment

2.     A system to make findings actionable

3.     A diligent, capable team dedicated to doing great work in the field


All three of these ingredients are needed to be successful. While we focus on providing the right tools for the job, it’s important to realize they’re only as effective as those using them on-site.


“If all three parts are working together, you can’t get wrong numbers that look right. If there is movement happening, you can quickly identify, localize and correct it.” – Todd Boyle, Manatee County Survey Division Manager

 

Adapting the model to other monitoring projects


In a broader mission of promoting safety and security everywhere, Manatee County has offered to make their proprietary monitoring spreadsheet available free to those who might also find benefit in using it to manage monitoring data.


Click here to download the spreadsheet template (.xlsx)


Simply follow the instructions found in the “Notes” tab to adapt the template to your monitoring project.


Together, with the right surveying tools and techniques, we hope to improve monitoring capabilities for all projects around the world.


Visit the Manatee County Survey Division website here to learn more about the Florida Surveyor and Mappers.


Click here to browse Berntsen’s selection of Rothbucher Systems smart targets, prisms and datums, or contact our team by phone or online today to learn more about how smart targets can provide advanced monitoring capabilities even in the most difficult locations.