The Ormond Beach Heritage Condominiums needed a new stormwater treatment system. The problem began when the present system wasn’t able to meet the site’s hydraulic requirements.
”Most of the problem was due to chronic flooding in the belowground parking garage,” said Michael Sims, project engineer for Point Four Engineering, Lake Helen, Florida. “The only way we could stop the flooding was to disable part of the existing system.”
The existing exfiltration trench was capturing and percolating storm water into the ground and into the garage. The condo management association wanted the problem fixed. The facility owner had high standards, and, in search of the best possible remedy, contacted Sims to help develop a storm water management solution.
Sims had not worked with the Vortechs system before, but he had done some research. Sims found a model that was big enough to handle the flows, but just as importantly, small enough to fit in the tight space where the system had to be located. “We had to balance treatment capacity with the available space we had for installing it. It was a very tight site,” he said.
Sims worked with his local Contech engineer and her technical team to specify a hydrodynamic separation (HDS) unit for Ormond Beach Heritage. The stormwater design engineer sent Sims all the treatment efficiencies that he needed for his submittal package. Now the engineering team had a working solution with all the proper documentation to make it stick.
The HDS system selected for this project is a high-performance system that uses a large swirl concentrator and flow controls to maximize treatment and remove finer sediment, particles, oil and debris. The flow controls physically separate and capture sediment and free oils and help prevent the resuspension and release of previously trapped pollutants. The design also allows for easy inspection and unobstructed maintenance access.
The six-acre site’s existing stormwater treatment system, a series of bioretention swales and detention ponds, was left online. However, all discharge now flows through the new treatment system. The added unit will work in combination with present systems to bring storm water treatment up to compliance with the Water Management District. Before discharged into the Halifax River, all flows will now be treated by the Vortechs system.
“We didn’t have much demolition because most of it was disabling the existing exfiltration trench and adding some pipe and catch basins,” said Sims. “Dewatering is expensive, and we were in a high water table area and very close to the Halifax River.” Since it was such a tight installation, a lot of digging occurred very close to the building, and extra caution helped keep the building stable.
The new system is anticipated to meet treatment expectations but will need to go through the upcoming rainy season before project coordinators can determine its true treatment capacity. Currently there is no permit requirement for testing the effluent flows.
The HDS system, in addition to the existing stormwater treatment methods, should now be fully operational and receiving the full impact of runoff from the site.