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existing vested flow levels , however, the current backlog of developments and new applications appear to be increasing at a greater rate then the data that was previously available . In order to adjust to those changes and to verify or revise the vision for service in the South and West Service Areas , a preliminary calibration of the County's flow projections and recommended improvements at the WWTFs was conducted by PBSU with input from County staff. The conclusion of this "calibration " is that the West Regional WWTF may reach its design capacity within the next two to three years , assuming diversion of flow from the South Service Area , increasing vested flows and continued growth in the West Service Area (See Figures 1 to 3) . PBSU and IRC staff have identified approximately 2 , 300 and 820 new equivalent residential units ( ERU ) in the West and South Service Areas , respectively , which may come online during the next two years . An estimate of completed subdivisions , individual occupied lots and developed parcels , according to IRC Metropolitan Planning Organization ( MPO) , have already been deducted from this count which results in new flows of approximately 0 . 78 MGD AADF combined for the South and the West Service Areas . The flows generated from the newly identified ERUs are approximately 0 . 57 and 0 . 21 MGD AADF for the West and South , respectively. When combined with an assumed backlog of vested flows of 0 . 20 and 0 . 40 MGD AADF for the West and South Regional WWTFs , respectively , actual flows , and the transfer of 0 . 75 MGD AADF from the South to the West Regional WWTF the potential flows at the West and South Regional WWTFs may be 2 . 52 and 1 . 36 MGD AADF , respectively. The 3 . 88 MGD AADF of potential flow plus vested flow that has been identified between the two facilities is below the combined permitted amount of 4 . 0 MGD AADF , however, the timing and amount of flow diverted from the South Service Area to the West Regional WWTF will be critical in remaining under existing permitted capacities . Since the South and West Service Areas will essentially operate as a combined service area and the treatment capacity of the South Regional WWTF is limited , it is important to consider the impact of any future improvements , developer or IRC driven , on both facilities and the ability to transfer flow to the West Regional WWTF . Future potential flows and percent plant utilization based on our proposed expansion to 6 . 0 MGD AADF is shown in the following table with flow projection methodology provided in the footnotes . Since the flow projections are based on a shorter term methodology, it will be extremely important to monitor the pace of growth and track vested flow versus actual flows seen in IRC 's facilities . The current pace of growth and vested flows based on the new short term data , results in approximately 3 . 0 MGD AADF increase over two to five years which is an extremely high rate of growth based on historical data . If this projected rate of growth were to continue , an expansion to 6 . 0 MGD AADF may not last ten years . This is , however, a conservative approach faced with the development the County is currently experiencing and making the assumption that the growth should begin to return to more moderate pace when the supply of new homes has increased P2 IRC WWTF Expansion May 2005