According to the WateReuse Foundation National Water Reuse Database, Florida leads the United States in the production and reuse of reclaimed water, also known as recycled wastewater. In fact, Florida has been irrigating its crops — mostly the citrus that the state is famous for — with reclaimed water for more than 50 years.
Reclaimed water is domestic wastewater that has been treated to remove solids and impurities. Once it has been cleaned, the water can be safely discharged into a local water body, or it can be used in communities for such activities as lawn irrigation. Florida uses about 45 percent of its reclaimed water as a way to save its potable water resources.
On the west side of Florida on a barrier island, Pensacola Beach maintains four large concrete tanks for reclaimed water. All four tanks, operated by the Emerald Coast Utilities Authority (ECUA), sit on the strip of land known as Sabine Point — right at the entrance to Pensacola Beach after crossing the bridge from the north. The fourth tank, built in early 2018, holds 2.5 million gallons (9,463,529.5 L) of reclaimed water, which will be used to irrigate public areas of the beach and will eventually be connected to nearby hotels, condos, and other structures.
The new tank sat unpainted for most of 2018, as at least eight months were necessary for the pre-stressed concrete of the tank to cure. When the ECUA put the painting job out for bid, Ken Brend of Jetco Ltd., who had previously done work for the authority, submitted a bid and won the job. “We have a history with the owner, and they were very happy to award it to us,” said Brend, president of Jetco. “We put a logo on one of their elevated water towers back in 2015. We also did some repair work, some rehabilitation, where they had to have parts of the steel structure repaired or upgraded; however, as it is a public utility, we still had to go through a competitive bidding process for this job.”
Waves of Blue
Jetco is a small company with 15 full-time union craftsmen. Four crew members were mobilized in April 2019, making the long drive to western Florida to paint the approximately 21,000 square feet (1,951.0 m2) exterior of the tank, including the roof. They were given 75 days to complete the project.
The crew began by preparing the surface using three Mi-T-M CW30044SGH 3,500-psi (24.1 MPa) pressure washers rented from Sunbelt Rentals. Three crew members performed the task while one remained on the ground, making sure lines weren’t getting tangled in the manlifts and ensuring that proper safety precautions were taken. All surfaces were pressure washed to remove dirt, efflorescence, and concrete dust. Because the concrete was relatively new, there were no contaminants to deal with in the rinse water. This process took three days. “Basically, you wash from the top down,” explained Brend. “So they washed the roof the first day. Then they washed the walls the final two days. After the walls were done, they started back up on the roof, painting.”
Before they got started with painting, though, the Jetco crew addressed some normal stress-cracking in the existing concrete substrate. With a bit of efflorescence coming through, they wanted to ensure that the owner had a chance to inspect these areas prior to painting and to thoroughly prep them for proper paint adhesion.
The three tanks already on the site had an attractive wave pattern of various blues, with white dolphins “jumping” through the waves. The Jetco crew had to replicate the design of the other tanks but with a different circumference. This meant taking measurements from the other tanks and extrapolating those measurements to the new tank. As Brend commented, “Each tank is a different size. You can’t just do exactly what was on the other tank because the pattern won’t repeat correctly on a different size tank. So you have to do a little bit of mental math and figure it out — make sure you get everything lined up right.” Even the dolphins were painted on — looking a lot like they might be stickers, as they were so well done.
All coatings were manufactured by Tnemec. The primer was Tnemec Series 27WB water-borne epoxy applied at 4.5 to 7 wet mils (114.3–177.8 microns), which dried to 4 to 6 mils (101.6–152.4 microns). The intermediate coat was Tnemec Series 1075 Endurashield II aliphatic acrylic polyurethane applied at 4 to 7 wet mils (101.6–177.8 microns), which dried to 3 to 5 mils (76.2–127.0 microns) dry film thickness. The mural with the dolphins and waves, which comprised the finish coat, was Tnemec Series 700 Hydroflon advanced thermoset solution fluoropolymer, applied at 3 to 5 wet mils (76.2–127.0 microns), curing to 2 to 3 mils (50.8–76.2 microns) dry film thickness. “You have about 16 hours and then you can recoat,” said Brend regarding the cure times for each coat. “So the next day you can overcoat.”
To minimize the environmental impact, brush and roller were used to apply the coatings. Paint application equipment was supplied by Wooster, including 6- to 12-foot (1.8–3.7 m) Sherlock extension poles, Sherlock 9-inch (22.9 cm) roller frames, Pro-Doo/Z 9-inch (22.9 cm) rollers with 3/8-inch and 1/2-inch (10 and 13 mm) nap, and 2 1/2-inch (6 cm) Alpha synthetic blend angle sash brushes.
While the crew was painting, the loose sand surrounding the tank required the use of specialized access equipment to properly reach all surfaces in an efficient manner. Genie S-65 Trax telescoping manlifts supplied by Sunbelt Rentals were obtained for the task.
Safety concerns included fall protection and hazard communication due to possible chemical exposures associated with coatings and thinners. Fall protection equipment, including harnesses, lanyards, rope grabs, and lifelines, was supplied by Gemtor. Other personal protective equipment included hardware store gloves, as well as hard hats in case of any danger of being struck by objects from above. While working on top of the roof, the crew members were tied off at all times to anchor points that were installed when the tank was built. All spent solvents were captured and returned to Jetco’s facility to be recycled. The crew did not have to wear respiratory protection due to working outdoors and not spraying any coatings. “We rolled and brushed everything, and we were outside, so there were no VOCs [volatile organic compounds] or anything hazardous that we had to deal with,” said Brend. “Had we sprayed or something, then yes, but not when you’re rolling and brushing.”
Due to the proximity of the water and ongoing site work associated with the construction of the tank, there were some adverse conditions that the crew had to overcome. Most notably, site grading and installation of rip rap drainage and erosion control work frequently impacted the job. At times, a truck would dump a pile of the large rip rap rocks directly at the base of the tank, causing the Jetco painters to work on the opposite side of the tank until the rocks were moved to the shoreline.
The crew also experienced a few days of rainy weather and wide temperature swings, common to this geographic area of Florida during the spring months. Thankfully, the project was finished well before hurricane season, so there were no concerns about interruptions caused by extreme weather events.
Although the Jetco team had to work around other trades and in a tricky environment, they completed the project in only 24 calendar days — well ahead of schedule. And now, local residents and visitors alike can enjoy the exterior coating on the fourth installment of the city’s reclaimed water tanks.
Editor’s note: Reprinted with permission from WaterCorr News, (Summer 2019).