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(CH2M Hill, 1989). Because of this high salinity, the UFA is currently used little in these areas for water supply. During the recharge phase of ASR system operation, the ambient groundwater would be displaced by the injected fresh water such that a zone, or “bubble”, of fresh water would be created and stored around each ASR well. This bubble of fresh water could be drawn upon later by the same ASR wells and the recovered water used to augment deficient surface water supplies during dry seasons or longer-term drought periods. In essence, ASR would use subsurface space in the UFA as the reservoir for storing water.

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FIGURE 1. Schematic diagram of the recharge and recovery phases of ASR for a typical south Florida system. The relatively symmetric spread of fresh water away from the well shown assumes a fairly homogeneous, isotropic aquifer with negligible regional flow relative to the flow rates induced by pumping during recharge or recovery. The actual configuration of the storage bubble may be considerably more complex. Modified from .

Concerns expressed about large-scale ASR in South Florida

ASR technology has been employed successfully in Florida since 1983 (Pyne, 1995), with individual well clusters having capacities up to about ten million gpd (38,000 m3/day). However, the proposed scale in the CERP of 1.7 billion gpd (6.3 million m3/day) is much larger than past projects. Implementation of ASR at the scale proposed in the CERP has raised a number of concerns among groundwater engineers and scientists in South Florida. Many of these concerns were outlined in a report prepared by the Aquifer Storage and Recovery Issue Team of the South Florida Ecosystem Restoration Working Group (ASR Issue Team, 1999) and presented to the Working Group in January 1999. The concerns addressed by the Issue Team, some of which were also noted in General Accounting Office (2000), were summarized in the following seven questions:

    1. Are the proposed ASR source waters of suitable quality for recharge without extensive pretreatment?

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