A two-year project aimed at measuring the effectiveness of the McIntosh Park enhanced stormwater treatment wetland (ESTW) is about to begin. The ESTW is a cooperatively funded project completed by Southwest Florida Water Management District, Plant City and Hillsborough County.
Vanasse Hangen Brustlin, Inc. has been contracted to monitor the water quality and flow rates at the McIntosh Park ESTW, which removes sediment and pollutants from a 6,000-acre watershed that drains into the Hillsborough River and ultimately to Tampa Bay.
The McIntosh Park ESTW is expected to be more effective than traditional wetland treatment systems at reducing nutrients like phosphorus, nitrogen and other pollutants because it uses a three treatment component consisting of a large sediment sump, a 45-acre herbaceous wetland and a chemical treatment system using aluminum sulfate (alum). A sediment sump is a pond that allows particles sink to the bottom and water to flow through.
Alum is a chemical agent that promotes the formation of solid particles, or floc. Nutrients and pollutants in the stormwater runoff attach to the floc and settle in the pond. The alum floc will be collected periodically, allowed to dry out, and then tilled into the created wetlands to improve their phosphorus removal efficiency.
Phosphorus stimulates algal growth. Therefore, limiting the amount of phosphorus entering the Hillsborough River system helps control algae, a primary water quality issue in the watershed.
Monitoring stations throughout the ESTW will monitor water quality and the rate water flows through the system. Water quality will be monitored between each treatment component to gauge the effectiveness of each component and how the system works as a whole. The goal of this evaluation project is to quantify the performance of each treatment component to determine the best design for future systems.
Twelve baseline water quality and flow measurements will be collected along with 24 samples collected during storm events throughout a two-year period. Other data, including rainfall, will also be collected at the site.
This project is expected to begin at the beginning of November and is expected to cost $257,610. The District’s Hillsborough River Basin Board and the Surface Water Improvement and Management program are each contributing $28,852 of the total cost. The remaining funds are provided by a grant from the Environmental Protection Agency.