Strategic Water Reclamation: CCUA Journey to 100% Reclaimed Water Utilization

As a leading reclaimed water service provider in Florida, Clay County Utility Authority (CCUA) serves a region experiencing rapid growth, with population expected to double in 25 years. CCUA operates 5 interconnected reclaimed water facilities (RWFs), providing 70% reclaimed water to the region (Fig 1), allowing CCUA to meet total maximum daily loads (TMDL) nutrient load objectives, provide an alternate water source for irrigation, and reduce Floridan aquifer reliance. From inception, the reclaimed water system has organically grown in response to rapidly expanding reuse demands. CCUA plans to continue expanding to meet future reclaimed water demands. Through its expansion, CCUA aims to achieve complete reuse across the county by 2031; however, CCUA's service area faces an imbalance: there is an excess of reclaimed water in the northern service area and a growing deficit in the southern section. Objectives To address this imbalance, CCUA commissioned a study to identify optimized operating protocols and capital improvements to transition the system from approximately 70% to 100% reuse. The study involved (1) forensic analysis of the reclaimed water distribution system flow and level data to identify operational issues and (2) hydraulic modeling to recommend operational and capital improvements. Status The study is complete and proposed a suite of $12.3 million in capital projects and supervisory control and data acquisition (SCADA) improvements that are being scheduled for design and construction in the next capital budget cycles. Methodology The study involved 4 tasks to identify subtle inefficiencies and inform model updates and recommendations. *Data Collection: A total of 3 years of flow, level, valve positions, and pump information were retrieved in as low as 2-minute intervals from the VT-SCADA historian to capture daily operations at a high resolution. Field inspections and operator interviews were conducted to understand operations under wet weather and seasonal conditions. *Data Analysis: Data analytics, mass balance, and statistics determined how system components typically operated: flow patterns, tank filling, and pump/valve operations. Initial results showed that wet weather had little impact on demand, but there were seasonal variations, with summer being the worst case. *Modeling: These data were used to update an Innovyze InfoWater Pro hydraulic model to simulate the existing system, proposed projects, and emerging demands. Given the database, SQL, python, and Power Query were used to develop summary tables and graphs. *SCADA Inspections: Metering, control automation, and data collection capability within the SCADA system were documented. Observations showed that some RWFs lacked output controllers to pace pumps and operate valves. Findings The study's findings underscore the need for enhanced automation coordination among the RWFs, more complete utilization of storage capacities, and isolation of transmission and distribution systems to optimize the distribution network. Key operational inefficiencies stemmed from RWFs operating independently without centralized control. This independent operation led to competitive behavior among facilities, resulting in inefficient water operation. For instance, Figure 2 illustrates frequent cycling of distribution pumps during non-peak times, far exceeding manufacturer recommendations. This not only risks water hammer and excessive wear on equipment but also results in erratic system pressures. Modeling also showed that water could not be transferred long distances without impacting pressure in local distribution systems. A focus area of analysis was periodic occurrence of discharge of treated reuse water into surface water concurrent with groundwater augmentation at the same facilities. These instances again showed an opportunity to automate the coordination of controls and fully utilize storage during peak irrigation demands. Again, Figure 3 presents river discharges for a major RWF predominantly occurring from late evening to early morning, tapering off to zero by hour 9. Concurrently, the facility experiences peak flow starting at hour 8., leading to a noticeable drop in tank levels by hour 7. Augmentation wells are activated by hour 9 to slow down this depletion. However, as the RWF's output reaches its peak and distribution demands decrease, tank levels recover, suggesting that if the tanks were allowed to deplete further without immediately resorting to well water, they could be replenished by the wastewater treatment facility (WWTF) supply, thereby avoiding surface water discharges. The recommended projects are to separate transmission pipelines from distribution networks, install additional dedicated pumping systems, construct new storage tanks, adjust augmentation well setpoints, and develop a universal SCADA controller for efficient water transfers. Significance The resulting investments will allow the system to effectively wheel water from areas of lower demand in the north to areas of continuously increasing demand in the southern part of the service territory, fully utilizing this resource. The insights gained offer a valuable model for other utilities with multiple gridded reclaimed production facilities, demonstrating how detailed analysis can improve operational protocols and optimize the system to more fully utilize the resource for minimum investment.