Dallas — Treating Florida’s source water is complicated. High water demand, a sensitive environment, complex water chemistry and multiple water sources all contribute to a complex water treatment environment. As demands increase, utilities are being challenged to seek out alternative water supply sources, treatment, storage and/or conservation. For Lee County Utilities in southwest Florida, the utility’s overarching goal was to find a cost-effective solution that would provide long term sustainability while increasing capacity.
Lee County Utilities’ new Green Meadows Water Treatment Plant (WTP), which celebrated its official opening on October 29, is the first-of-its-kind plant in southwest Florida, combining new with existing technology to treat water from three different aquifers using the latest, large scale treatment technologies. Jacobs served as the prime engineer on the project, beginning with early evaluations more than a decade ago.
The new 14 million-gallons-per-day (mgd) facility replaces an aging lime softening plant, previously in operation for more than 35 years and at the end of its useful life.
The Green Meadows WTP includes a reverse osmosis (RO) system (for desalinating brackish well water), paired with an innovative ion exchange (IX) system (cation and anion exchange used to remove iron, hardness and organics from surficial aquifer fresh water), fresh water blending using a third aquifer source, degasification, disinfection and finished water chemical addition. This blend of proven, innovative technologies combined under a single system provides a dynamic, cost effective treatment plant that increases the county’s water supply treatment flexibility and reliability while reducing operational costs and treatment costs by as much as 60 percent.
The $75.4 million project – serving up to an estimated 30,000 area homes and businesses since August 2018 (and with capacity to serve up to 60,000) – includes a process building, office/operations building, standby generator, shared chemical systems, raw water sand strainers, a backwash waste pumping station, eight Upper Floridan Aquifer wells, modifications to 27 existing wells, seven electrical buildings, a 2,873-foot-deep injection well to dispose of treatment concentrate, eight miles of production well piping and five miles of service road to the production wells.
“The plant is located adjacent to environmentally sensitive areas, so it was critical to minimize disturbances to sensitive species of the nearby Imperial Marsh, as well as the deal with the logistics of seasonally flooded roads,” Jacobs Project Manager Bill Beddow reflected on additional civil engineering and site challenges beyond the water treatment regime. “The entire main plant site had to be built up two feet to be above the local high flood water level, and 67 culverts had to be installed along the road to maintain the natural wetlands sheet flow.”
Construction of a paved 5-mile-long, single lane road through the marsh required installing sixty-seven 36-inch diameter culverts, with 24 culverts alone between wells 4 and 5, and 12 culverts between well sites 11 and 12 (at Imperial Marsh), to help maintain sheet flow, while also allowing utility staff to inspect and maintain distant production wells, he added.
Jacobs’ proprietary tools
The team used Jacobs’ proprietary Source water quality and treatment modeling tool to quickly identify impacts of blending on treatment and optimize options for further proof pilot testing. They used Jacobs’ CPES tool to develop costs for various treatment variations and capacities to define best value options. Jacobs’ Bridge design tool allowed the project team to quickly and cost effectively complete the design, while Jacobs’ Preview tool helped provide 3D representations early in the design process to help solidify design decisions early. The Jacobs’ Replica tool provided the opportunity for dynamic simulations to optimize energy efficiency and confirm wellfield and plant hydraulics.
Despite numerous obstacles, including multiple wildfires, category 3 Hurricane Irma and the wettest January on record, the team persevered to deliver this state-of-the-art treatment plant under budget and on schedule, with approximately $1.5 million in cost savings for to Lee County. On Monday October 29, 2018, Lee County Utilities had their official ribbon-cutting ceremony and facility tours.
“This new water treatment plant uses modern technology and reduces the use of energy and chemicals, driving new efficiencies in water treatment while maintaining the same high-quality water to residents,” said Cecil Pendergrass, Lee County Board chairman and District 2 representative. “It also increases service capacity to more Lee County residents and businesses both now and in the future.”
The Environmental Business Journal awarded the Green Meadows WTP with a Technology Merit Award for Water Supply. Selected for developing a first-of-its-kind sustainable water supply combining new and existing large-scale treatment technologies to process water from three different aquifers, the plant increases the county’s water supply flexibility and reliability while reducing operational costs by as much as 60 percent. The water supply, in addition to the 30,000 homes and businesses, serves the Southwest Florida International Airport and Florida Gulf Coast University.
The project is also shortlisted for a Global Water Award for Water Project of the Year, which will be presented in London on April 9, 2019.