I recently saw a
story about a natural swimming pool in Minneapolis. Having grown up on the Outer Banks of NC, I rarely swam in a pool, but almost daily in the summer took a dip in the ocean or the sound. Living far from the coast now, my kids and I spend plenty of time in swimming pools (all year – they are competitive swimmers), and sometimes the sweet smell of chlorine gets a little overwhelming. The pool in Minneapolis was once a freshwater swimming hole, but pollution eventually led to the use of a chemically treated pool. After that pool closed in 2010, park planners and residents put a focus on eco-friendly design and innovation, including development of a natural swimming pool.
Here’s how it works:
- Gravity carries water from the pool’s overflow gutters to an underground filtration tank that catches small particles of debris. Water drains from the tank into the regeneration basin.
- In the regeneration basin, ultraviolet sun rays, zooplankton, and biofilm covering the basin’s gravel bed all help reduce bacteria.
- Thousands of aquatic vegetation planted into the gravel bed feed on excess nutrients to help limit algae growth and keep water clear.
- A network of drain tile disperses water throughout the basin, and two pumps send clean water back into the pool.
- Pool staff cleans the biological filters daily, and during off-hours three small robotic vacuums remove algae from the pool’s liner
All 500,000 gallons of pool water complete a cycle from the pool to the regeneration basin and back to the pool every 12 hours. Daily care keeps plants healthy and prevents debris from accumulating, and when fresh water is added to offset plant uptake and evaporation, it first passes through a phosphate filter to minimize algae growth. I would love to visit a pool like this one day! - Beth Sciaudone, DTC Civil Water Resources & Environmental Instructor
Mechanical Engineers - Change Is Coming!
You Should Take the PE Exam Now.
