South District Wastewater Treatment Plant HLD Upgrade to 285-MGD Filter System, Contract S-805 Miami, FL

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CLIENT OBJECTIVES

To upgrade its water filtration system capacity, as well as reclaimed water standards.

SCOPE OF SERVICES

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. To this end, P&K’s contract required multiple phases of construction and twelve distinct Substantial Completion (SC) milestones to maintain smooth operation of the existing treatment facility and coordination with related projects being constructed by others. As of this date, P&K has achieved ten of those twelve milestones ahead of schedule, and anticipates completion of the remaining SC milestones, as well as Final Completion of the project, ahead of schedule. During construction of the project, the Owner elected to substantially upgrade the control system for the filters from manual controls to a customized web-based, fully automated control system utilizing allowance funds provided within the contract.

P&K’s contract also required full-scale performance testing of the filter system to meet the specified performance requirement of less than 5 parts per million total suspended solids (ppm TSS) in the filtered effluent. During testing, the system far exceeded this Contract requirement, consistently producing effluent with TSS of less than 1 ppm.

SOLUTIONS

In June 2008, Poole & Kent Company of Florida (P&K) was awarded the contract for construction of the HLD Filter System Upgrade, one of the largest deep bed sand filter systems in the United States, consisting of 30 cells measuring 15.25 feet by 88 feet with six feet of sand filter media and with space for future expansion up to 48 cells.
Improvements included under the project include the following components:

  • Three flocculation trains built within a single cast-in-place concrete tank, each equipped with flash mixing followed by slow mixing to enhance solids removal by the downstream filter system.
  • Thirty deep-bed sand, mono-media wastewater filters, including cast-in-place concrete basins, a filter underdrain system, filter media, washwater troughs, filter gallery piping, and control instrumentation.
  • A filter backwash system consisting of three 275,000-gallon cast-in-place concrete backwash water supply tanks, eight horizontal split case, 200 horsepower (Hp), 8,000 gallons per minute (gpm), constant speed backwash pumps, backwash piping, and associated electrical, instrumentation, and controls.
  • An air-scour system for the filter backwash system consisting of seven 500 Hp, 12,000 cubic feet per minute (cfm) positive displacement air blowers, air piping, filters, silencers, and instrumentation and controls. A backwash waste handling system consisting of three 500,000-gallon cast-in-place concrete waste washwater tanks and eight horizontal split case, 200 Hp, 8,000 gpm washwater pumps equipped with variable frequency drives, wastewater piping, and associated electrical, instrumentation, and controls.
  • An air-scour system for the filter backwash system consisting of seven 500 Hp, 12,000 cubic feet per minute (cfm) positive displacement air blowers, air piping, filters, silencers, and instrumentation and controls. A backwash waste handling system consisting of three 500,000-gallon cast-in-place concrete waste washwater tanks and eight horizontal split case, 200 Hp, 8,000 gpm washwater pumps equipped with variable frequency drives, wastewater piping, and associated electrical, instrumentation, and controls.
  • A 22,200 s.f. North Filter Building to house air blowers and backwash supply and waste pumps for the North Filters, and a 22,200 sf South Filter Building to house the air blowers and backwash pumps for the South Filters, both buildings including architectural, structural, electrical, HVAC, and plumbing systems.
  • A polymer filter aid storage, preparation, and feed system housed in a 4,200 s.f. Polymer Building.
  • All associated sitework, yard piping, electrical, instrumentation, and controls improvements.

In addition, shortly after the Contract was awarded to P&K, MDWASD replaced the project’s electrical engineer. The new electrical engineer modified a substantial portion of the electrical design. The changes not only affected the electrical portion of work, but also the structural, mechanical, and instrumentation work. These changes were made as the respective work was being performed. P&K coordinated these changes between the design team and its electrical subcontractor, as well as it’s others subcontractors, while at the same time maintaining and improving upon the project schedule.

BACKGROUND

In 2004, Miami-Dade 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 (previously known as Miami Metro Zoo). Due to the aggressive completion schedule mandated in the Decree, planning, pilot testing, design, and construction were fast-tracked.

PUBLIC/GOVERNMENT
UTILITY


OPERATING COMPANY:

Poole & Kent Company of Florida

CLIENT:
Miami-Dade Water & Sewer Department

ENGINEER:
Hazen and Sawyer

GENERAL CONTRACTOR:
Poole & Kent Company of Florida

SCHEDULE:
August 2008 to August 2013

COST:
$134,253,000

 

Poole & Kent Company of Florida - Technical Solutions, Relationships, Quality Service, Value Engineering, Experience, Project Schedule & Coordination, Expertise

 

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