As early as the 1970s, Cape Coral, Fla., was looking to expand its water resources. State-controlled fresh water supplies clearly were not sufficient to support the city’s rapid population growth.
Cape Coral embraced reverse osmosis (RO) technology that was fairly new at the time, and decided to drill down to the Floridian Aquifer and desalinate its brackish water. The city was determined to create its own potable water.
The first production wells and RO treatment plant went into operation in 1976. An expansion was implemented in 1985. The city went through a number of changes to its treatment plants over the years, and when it expanded its facilities again in 2004, the Cape Coral was clear about the obstacles it faced with well components, particularly well casing and drop pipes.
MWH Global Inc. was awarded the contract for the design and construction of the recent expansion. Diversified Drilling Inc., headquartered in Tampa, Fla., was chosen to install the new wells. Twenty-two production wells were installed in the North Cape RO water treatment plant, and eight wells were installed in the Southwest RO water treatment plant.
Major issues that confronted the project included corrosion, strength/pressure resistance, heat resistance, installation and cost containment.
Corrosion ConcernsCorrosion caused by the high salt content of water in the aquifer was a major issue. Gordon Kennedy, MWH’s project manager, cited the inert nature of glass fiber as a major reason for selecting Burgess Fiberglass casing for the project. As an inert material, glass fiber is not subject to chemical attack, and does not corrode from contact with brackish water. Further, Burgess had a track record with the city. Burgess casing had been successfully installed in the Cape Coral’s RO treatment plants since the 1970s. As an inert material, fiber also is low-residue forming, protecting the sensitive membrane systems that are an integral part of the RO system.
Strength/Pressure ResistanceKennedy also cites the strength of glass fiber casing as a reason for its selection. The compressive strength of glass fiber casing enables it to be installed in very deep well depths. The strength of glass fiber also withstands the weight of cement poured at installation. It also withstands the start-up torque created by high-horsepower pumps.
Heat ResistanceRalph D’Elia, of Diversified Drilling’s Lehigh Acres, Fla., office, cites the pressure- and heat-resistance of Burgess casing as important criterion for selection. High-pressure capabilities and heat-resistance allow for faster and more cost-effective installation of casing. “It takes fewer shots of cement to install Burgess Fiberglass casing because it resists pressure and heat,” he remarks. D’Elia has supported the city’s treatment plants for eight years. During the first two years, he pulled pumps from the bottom of wells fairly often due to hour-glassing. The installation of Burgess Fiberglass drop pipes and installation of safety devices (flow shut-off, etc.) resolved this issue.
Installation IssuesIn addition to the ability to grout glass fiber casing more quickly, Kennedy and D’Elia also point out other installation advantages. Elevators attach easily under the female bell end of Burgess Fiberglass casing. Joints are aligned, threaded and bonded together quickly – without special skills. Fiberglass is lighter and easier to handle than some other materials. Prep time and installation time can be significantly reduced.
Cost ContainmentAn additional benefit outlined by MWH’s Kennedy is the economic benefit of using glass fiber. Kennedy states, “Fiberglass is cheaper in the long-term when compared to other types of pipe.”
The cost of installation also is another important factor. The installation of metal can be time- and labor-intensive. Welders are highly skilled, and the extra cost of men and drilling rigs is prohibitive when compared to installing lightweight, threaded glass fiber casing. Finally, the long service life of Fiberglass (40 years at the city) contributes to cost containment. Removing and re-installing casing and drop pipe is expensive.
Project CompleteBurgess Fiberglass casing was installed in all 30 of Cape Coral’s new RO production wells. For these wells, 12-inch casing was installed and pressure grouted from the bottom. Glass fiber drop pipe also was installed in the production wells. Casing was connected to stainless steel fittings running to the plant. This portion of the city’s water treatment plant expansion was completed in 2010.