Sarasota County’s 10th Street Bafflebox works to prevent stormwater and sediment pollution from reaching the Sarasota Bay
By Brianna Fries
When the rainy season hits, it is great to know that your city or county has invested in their stormwater infrastructure. This means residents of the area can rest easy knowing they are at a reduced risk of flooding, road damage, and other harmful effects of stormwater.
It is even better to know that your county has gone the extra mile to ensure that their stormwater infrastructure includes a filter that protects the surrounding lakes, rivers, and other bodies of water.
This is exactly what Sarasota County in Southwestern Florida decided to do.
Funded by the Sarasota County Government, Southwest Florida Water Management District, and the City of Sarasota, the completion of the 10th Street Bafflebox is the first part of a three-chamber filtration system project.
With a project team that was committed to improving the quality of stormwater run-off being discharged into the Sarasota Bay, it is no surprise that this project was completed quickly – despite an initial failed procurement progress due to conditions at the construction site. Thankfully, once the challenges at the construction site were resolved, the team was able to complete the project quickly and successfully.
The construction for the 10th Street Bafflebox began in April of 2018 and was completed by November of the same year.
The 10th Street Bafflebox was created to treat runoff from a 467-acre watershed. The project team estimated that the resource would reduce sediment loads to Sarasota Bay by 72,000 pounds per year.
“This type of system is a unique and creative alternative to provide improved water quality in the Sarasota Bay estuary by removing trash, suspended solids and oils from stormwater runoff within this urban watershed,” explained Sarasota County Public Works Director, Spencer Anderson.
The overall goal for the project is to reduce the amount of sedimentation that has been entering the Sarasota Bay, thereby improving water quality at a major outfall. The use of a bafflebox to accomplish this is a universally accepted preventative measure. Rather that attempting to clean pollution after it has been discharged into the environment, the box allows the county to prevent and capture pollutants ahead of time.
“Massive algal blooms in Lake Okeechobee and persistent red tide in the Gulf of Mexico along the west coast of Florida have increased environmental awareness and concern in our community,” detailed Sarasota County Environmental Specialist Rene A. Janneman. “The county is confronted with the difficult task of addressing those concerns. This second generation Bafflebox is an innovative way to cope with multiple pollution streams and meet regulatory requirements. This type of device along with encouraging personal responsibility for environmental issues is an excellent step in protecting our natural resources.”
When the planning and design process was in full swing, those involved in this project had to be sure they identified and anticipated any possible challenges the Bafflebox could create or encounter. By approaching the project in this manner, they were able to design a box that considered buoyancy challenges, where the best location would be, what effect the restricted water flow may have, construction considerations such as modeling and elevation levels, and more.
As anyone can tell, a large amount of thought went into this project, resulting in an effective and efficient way to reduce pollution. The box was designed to be affixed to a sheet piling to prevent positive buoyancy, which could have otherwise put it at risk of pushing out of the ground when the water table rose. Additionally, the team was able to determine that placing the Bafflebox upstream of the boat basin to prevent infiltration of seawater and marine bio-fouling. They also followed this up by installing grates that would capture any floatable trash further downstream.
As an added bonus, the 10th Street Bafflebox is constructed to operate passively, using the upstream and downstream energy of the water system for flow control and energy.
The size and capacity of the box is unique, as is the location since it factors in changing tide tables and boat basin inflow. The box filters out a variety of items, including oils, sediment, trash, and larger items, which are captured in the boom.
Stated the City of Sarasota Project Manager Bill Nicholas, “An effective stormwater system that promotes environmental health is a benefit not just to our local residents, but the entire region. That’s why it made so much sense to partner with Sarasota County and the Southwest Florida Water Management District on this project. It also allowed us to maximize our collective resources and efforts to design, build and maintain the baffle box going forward.”
This 10th Street Bafflebox is one of many that have been installed in the surrounding area over the past 20 years. Combining this with the use of street sweeping and water goats (underwater nets used to capture trash), Sarasota County is showing a continuous effort to address and minimize water pollution.
The county seems eager to continue the good work too. They plan to install an additional 14 water goats throughout the county to improve the preventative measures that they are taking to protect their local bodies of water. They expect the entire project to cost a total of $230,000, including installation, maintenance, and outreach during the three-year-long replacement process.
The project requires a specific attention to maintenance. It will operate most successfully with routine inspections and updates. The lack of routine maintenance could cause pollutants to clog the drainage system, resulting in flooding upstream. Conversely, regular maintenance and consistently schedules inspections will ensure that the Bafflebox will be in working service for many decades, defending the shoreline and the water from harmful pollutants.
The Bafflebox is already having a tangible effect on the pollutants entering the bay. The staff has already identified a process for measuring the quantity of the sentiment collected through this project. The design was also created with maintenance in mind; each area was closely examined and considered in terms of ease of access for cleaning and maintenance. By putting thought into each aspect of design and upkeep, paired with the results already being seen, other projects with similar goals and designs are likely to follow suit.
While maintaining this project may require consistent upkeep, it is a vital protection that the bay has gained against various pollutants. When water supply is such a valuable resource, this project becomes more than a filtration system; it is an investment into the community’s health and wellbeing.
“This project is sure to have a positive effect on the health of Sarasota Bay and marine life,” added the City of Sarasota Sustainability Manager, Stevie Freeman-Montes. “It will greatly reduce the amount of nitrogen entering the bay, which we know can be a contributing factor in the red tide algal blooms that have plagued our community. It’s one great example of what local governments are doing to help our environment and preserve our quality of life.”
Brianna Fries is the Editor for American Infrastructure Magazine. She can be reached at firstname.lastname@example.org