Gypstack Closure Phase I OGS-S Compartment

In March 2021, over 200 million gallons of polluted water flowed into Port Manatee and Tampa Bay after a leak in the Piney Point Phosphate Processing Facility’s containment wall liner. This facility processed phosphate rock, leaving behind materials like calcium sulfate, gypsum, uranium, and radium, along with wastewater.
 
The polluted water was stored in a lined reservoir pond. When the leak occurred, the untreated wastewater was pumped into Tampa Bay to reduce pressure on the leak. This wastewater, though not radioactive, contributed to ongoing toxic algal blooms and fish kills due to elevated levels of nitrogen and phosphorus.
 
By January 2022, Piney Point still held 397 million gallons of wastewater, raising concerns among officials about how rainfall would affect water levels at the site. Ultimately, by March 2022, the state approved a plan to close the facility, aiming to complete the plan by late 2024.

Forgen responded quickly once the state enacted a plan to close the Piney Point Gypstack Complex. We began work in July 2022 in partnership with our client, Donica Receivership Services. This industrial site remediation project started with implementing surface water controls to allow construction to occur in a dry environment and prevent pollution of nearby watercourses.

To address access limitations for placing concrete for the open weir on the west dike, we utilized Gunite, a trade term for sprayed concrete. Gunite, distributed by a hose at high velocity, enabled us to reach awkward surfaces such as tunnels, bridges, swimming pools, and train stations. Unlike traditional concrete, which is poured onsite, sprayed concrete is dry and attaches quickly to the host surface.

We also sewed and placed high-strength geotextile fabric over soft marine dredged sediments, ensuring stability and support for the subsequent layers. We installed a 6-18″ collection drain system to manage water flow effectively. Additionally, we managed the onsite material stockpile operations, ensuring efficient use and placement of materials throughout the construction process.

The final capping and cover included the woven geotextile over the dredged material, a sand tailings layer over the geotextile, the collection drain in the sand layer, a gas vent system on top of the sand, and the HDPE liner with a compacted soils cover over the entire compartment. We also installed a stormwater drainage system and completed the project by grassing the entire area.

Given Piney Point’s proximity to sensitive marine resources, we heightened the importance of environmental safeguards and water resource protections at the site. Our work has ensured that future rainwater will not need treatment after coming into contact with the phosphogypsum sediments in the pond. We completed the terminal closure of Piney Point safely and without downtime in September 2023, showcasing our expertise in heavy civil construction and industrial site remediation.