Julington Creek is a 4,200-acre (1,700 hectare) planned community, featuring woodlands, lakes, a library, a recreational facility, and 18 holes of golf. Developed under Florida’s CDD (Community Development District) program, the community is located in south suburban Jacksonville, close to the east bank of the St. John’s River.
Built in the early 1990’s, Julington Creek needed an on-site wastewater treatment plant to treat municipal wastewater, with plans to re-use some of the filtered wastewater for golf course irrigation. The influent BOD averaged 180 milligrams per liter and the suspended solids averaged 160 mg/L. The plant had to be able to handle about 1,600 homes initially, and as many as 6,500 homes over the next 15 years as the community expanded.
Designed by England, Thims and Miller of Jacksonville, and started up in March 1995, the wastewater treatment plant is running well. It is a simple, efficient plant, with all treatment processes in above-ground, concrete structures.
Key to the plant’s success is a Hydro-Clear® pulsed-bed sand filter. The initial 1994 installation included a three-cell Hydro-Clear filter, which was expanded to six cells in 1997. The gravity flow filter uses a 10-inch (0.254 m) bed of fine sand, and the compartmentalized underdrain is designed to allow pulsing of the bed and efficient backwashing. The filter is equipped with a Chem-Clean® cycle to clear the bed of grease and oil. This is accomplished by soaking the bed with an emulsifying detergent, and then backwashing the grease and oil out of the filter bed and restoring the sand to its original condition.
Wastewater enters the plant through bar screens and then passes to a modified sequencing batch reactor, where biological treatment and nitrification take place. Digested sludge is hauled and spread wet on nearby fields. Approximately ten batches of biologically treated wastewater are sent to the Hydro-Clear filter each day. Filtered effluent is chlorinated and stored in a holding tank.
The effluent from the Hydro-Clear filter contains less than one milligram per liter suspended solids and less than one NTU turbidity, which more than meets the permitted levels of 5 mg/L suspended solids and 3 NTU turbidity. Alum is available for phosphorus removal, but so far that process step has not been necessary.
During normal weather, the filtered wastewater irrigates the golf course, and there are plans to use it on median strips and landscaping. In wet weather, the water is dechlorinated and discharged under a permit to the St. John’s River.