Construction and building in Florida is not easy. Due to the high-water table in the state, rising sea levels, and long-term challenges with water intrusion, every project that involves excavation also requires powerful pumps that can dewater and protect job sites.
Holland Pump Company is up for the challenge. For more than 40 years, the Florida-based company has delivered innovative pumping solutions for customers across the southeastern United States.
Recently, Holland Pump was selected to perform foundation dewatering for Aria Reserve in Miami, Florida. A project by Miami-based developer Melo Group, the condo complex is set on five Biscayne Bay waterfront acres in one of Miami’s most popular neighbourhoods, Edgewater. Upon completion, they will be the tallest residential waterfront dual towers in the United States.
“In designing the dewatering solution, our first priority was to provide stability for the construction,” says Chris Rhule, Holland’s South Florida Pump Consultant. As part of the project, Holland Pump’s team took into consideration some of the unique aspects of the region and the project site.
For example, the solution needed to account for “king tides,” which occur annually and predictably, in September through November in Miami. These tides are higher than normal and typically last about three hours. King tides may cause residents to experience “sunny day flooding” where a street or other areas will temporarily become flooded when it is not raining. Furthermore, the water table at the site is the same as sea level, which poses the possibility of water intrusion to the site.
To keep the site safe and workable in the face of such challenges, the civil engineering team proposed installing sheet piles to a depth of 30 feet from the ground surface. Sheet pile walls support the excavations below-grade to allow parking structures, pile caps, and foundations to be constructed. The team also proposed dewatering the excavation. In this instance, dewatering is the process of controlling groundwater. Water intrusion can threaten ground stability, as well as a stable worksite. Dewatering by wellpoints, submersible pumps, open sumping, and other methods provide a workable excavation for the foundation to be constructed in the ground.
When a pump system fails in Miami, the job site can be under water in a short time, potentially damaging construction equipment and delaying the construction schedule by several days. Holland Pump has a reputation for proposing and executing dewatering systems that keep projects on schedule by keeping pumps running 24/7, often using telemetry in conjunction with pump watch to respond to any indications of potential or actual shutdown of a pump system.
The proposed construction dewatering plan includes the use of 8-inch diameter hydraulically driven submersible (HDS) pumps. The pumps will be installed inside the sheet piling wall in the alcoves, and within sumps approximately four feet below the bottom of the pile caps. Each of these pumps has a pumping capacity of approximately 2,450 gallons per minute. Each pump will discharge the dewatering effluent to a separate 18,000-gallon sedimentation tank to allow any sand or silt to settle before 10-inch & 8-inch diameter suction lift pumps transfer the water to the eight stormwater deep disposal wells located around the site.
Since the anticipated dewatering effluent will most likely have high turbidity, the initial pumping rate is estimated to be 500 gallons per minute per submersible pump until the turbidity of the effluent has been reduced significantly. Thereafter, the maximum pumping rate is anticipated to be increased as appropriate for maintaining the depth of the water table for that shear wall excavation to be dewatered.
Holland Pump can use flocculant logs for additional settling if necessary. Each of the deep disposal wells will be capped and sealed to maximize flow capacity and are estimated to have the capacity to handle a discharge rate of 2,000 gallons per minute or greater.
The team anticipates a pumping rate for the garage shear walls of no more than 500 gallons per minute, but this also depends on maintaining the depth of the water table so that the the team can dewater the shear wall excavation.
Holland Pump will have 12 pumps on site for the South Tower, and the same for the North Tower. Dewatering is predicted to take up to six months for each tower. After the construction dewatering activities are complete, each of the wells will be converted into stormwater disposal wells.
“We’re excited to work on this project,” adds Rhule. “We’ve built a reputation for managing challenging sites and making it possible to construct beautiful buildings in our region.”
Image: Melo Group – Courtesy of Aria Reserve.