New Approach to Detention Pond Evaporation Saves Money

CHANGE

To increase the rate of evaporation, the Junction Maintenance Station (4468) uses its brine pump and inexpensive lawn sprinklers to spray the water from its pond onto the sun-heated pavement surfaces that drain back into the pond. 

This practice expands the water’s surface area 3 to 4 times, accelerating evaporation and making it possible to lower the water level in the pond quickly. For example, in July 2025, they evaporated an average of 689 gallons of water per hour over five and a half days (see the linked spreadsheet).

RESULT

Using this process, the crew can empty their detention basin within 4-6 days for its annual cleaning, and they avoid paying water disposal fees throughout the year. In 2025, they avoided hauling away over 25,000 gallons of water, saving them over $27,000.

An added benefit is that the evaporated water leaves behind salt that can be swept up and returned to their salt pile for use next winter.

This solution is cost-effective because they were able to use the brine pump and hoses they already owned. Sprinklers and fittings were inexpensive, and the system does not take long to set up when needed.

Next Steps: The crew will swap out metal fittings for plastic fittings that will not corrode in the salty water.

The crew noticed that some of the largest evaporation rates occur when the pump runs for a short time, so they are considering running the system in a “pulsed” manner. They would wet down the pavement area, shut off the pump, let it dry, and repeat. This approach would make it unnecessary to run the pump for hours at a time, while also taking advantage of the thermal effects of hot pavement in direct sunlight. With care, this method could be used in areas where the pavement does not run directly back into the pond. Crews would need to make sure they wet down the pavement and stop before creating runoff. In such a case, cleanup would be necessary before the next storm event.