Miami-Dade County South District Wastewater Treatment Plant High-Level Disinfection (HLD) Upgrade Chlorine Contact Tank Nos. 5 to 9, Miami, FL
New chlorine contact tanks will provide high-level disinfection of reclaimed wastewater from the County’s new 285 mgd High Level Disinfection (HLD) treatment facility. The disinfected, reclaimed water will be suitable for use as electrical cogeneration cooling water and for irrigation of green space at Zoo Miami (previously known as Miami-Dade Metro Zoo). Due to the fast-track schedule and extraordinary volume of construction performed concurrently on site under other contracts, Poole & Kent’s (P&K) construction contract required extensive planning and coordination with the Owner and other Contractors. During the construction phase, the Owner requested the addition of a $1.2 million coating system to the structure. P&K accommodated this addition to the contract and still completed the project within the original contract time and nearly $500,000 less than the original contract price.
To improve and increase its wastewater handling capacity.
SCOPE OF SERVICES
In 2004, the Miami-Dade County Water and Sewer Department (MDWASD) entered into a Consent Decree with the United States Environmental Protection Agency which mandated that the County’s South District Wastewater Treatment Plant be upgraded to incorporate a 285 million gallon per day (mgd) capacity reclaimed water filtration system. In addition, the Decree mandated that the facility meet Florida Department of Environmental Protection (FDEP) High Level Disinfection (HLD) reclaimed water standards, as well as water quality equivalent to primary drinking water standards. This facility will be the largest in Florida to treat wastewater to these stringent standards, and the treated wastewater will be reclaimed for use as electrical cogeneration cooling water and for irrigation of green space at Zoo Miami. Due to the aggressive completion schedule mandated in the Decree, planning, pilot testing, design, and construction were fast-tracked.
Separate contracts for five of the largest construction components of this HLD treatment program were awarded to Poole & Kent Company of Florida (P&K). These contracts included a new 285 mgd filtration system, a 123 mgd capacity effluent pump station, a septage receiving and solids process building, a new oxygenation train (no. 7), and chlorine contact tanks 5 through 9. The Chlorine Contact Tank No.’s 5 to 9 project is discussed herein.
In January 2009, Poole & Kent Company of Florida (P&K) was awarded the contract for construction of the Chlorine Contact Tank No.’s 5 to 9. Improvements included under the project consist of the following components:
- Five new 38 ft. x 48 ft. cast-in-place chlorine contact basins, each equipped with a 72" x 72" sluice gate, a 60" x 60" actuated sluice gate and a 48" x 48" sluice gate. The installation also included two additional two 48" x 72" slide gates and six 96", 72", and 60" diameter butterfly valves. These structures required approximately 7,000 cubic yards of concrete pours.
- One tank drain lift station
- Approximately 2,035 linear feet of 120", 108", 96", 84", 72", and 60" prestressed concrete cylinder pipe (PCCP) and other extensive yard piping, including one hot-tap connection to an existing 72" PCCP main.
- Extensive yard electrical demolition and new construction
- Each tank has 100% solids epoxy coating to all interior surfaces which was included in the Contract as additional work.
P&K was responsible for scheduling, coordination, procurement, and execution of all aspects of construction of the facilities and process equipment. Due to the high volume of construction work being conducted on the site by other contractors outside of the filter project (14 other construction contracts were under way concurrently), successful completion of the project required extremely close coordination and cooperation with the Owner, Engineer, and other construction contractors. During the construction phase, the Owner requested the addition of a $1.2 million coating system to the structure. Prior to the additional work being added to the original project schedule, Poole & Kent Company of Florida was 11 months ahead of schedule. P&K accommodated this addition to the contract and still completed the project within the original contract time.
The Miami-Dade Water and Sewer Department serves the needs of Miami-Dade County residents, businesses, and visitors by providing high-quality drinking water and wastewater disposal services while preparing for future economic growth through progressive planning; implementing water conservation measures; safeguarding public health and the environment; and enabling continuous process improvements and cost efficiencies.