Florida Geological Survey


mg/L, and a TKN value of 2.3 mg/L (again, probably low because the analysis was conducted soon after well development). After injection started in April 1989, chloride values rose from about 900 mg/L to over 1,800 mg/L in 1991. TDS values increased from 1,600 mg/L to about 3,200 mg/L. TKN values were very erratic.

 Port Malabar

 The Port Malabar injection well has a total depth of 3,009 feet BLS in the Oldsmar Formation. The confining zone, defined by CH2M Hill (1987) as an "intra-aquifer low permeability zone," extends from 1,300 to 2,050 feet BLS. The injection zone extends from 2,050 feet to 2,300 BLS (Appendix A6). The dual zone monitor well at the site has an upper monitor zone from 400 to 472 feet BLS in the lower Ocala Limestone and upper Avon Park Formation, and a lower monitor zone from 1,534 to 1,630 feet BLS in the lower Avon Park Formation.

 The confining zone from 1,300 to 1,470 feet BLS is predominantly wackestone, with a few interbedded packstone layers (Appendix A6). Porosity ranges from 10 percent to 25 percent and permeability generally appears to be high. In this interval, the rocks are moderately indurated. From 1,470 to 1,640 feet BLS the rocks are interbedded dolostones, mudstones and wackestones. Porosity in the mudstones and dolostones ranges from 5 to 15 percent. The dolostones are well indurated and have low permeability, and the mudstones are poorly to moderatley indurated and have low permeability. The wackestones are moderately indurated, generally have high permeability, and porosity ranges from 15 to 20 percent. From 1,640 to 1,880 feet BLS dolostone is the dominant rock, and there are several zones where chert is thinly interbedded. Porosity in this interval is five percent to 15 percent, permeability is low, and induration is good. From 1,880 to 2,050 feet BLS the rocks are interbedded dolostones, wackestones, and packstones. In the dolostones porosity ranges


from five percent to 15 percent, permeability is low, and induration is good. The wackestones and packstones have porosities ranging from 15 percent to 20 percent, generally high permeability, and are moderately indurated.

 The only background water-quality information available for the lower monitor zone is a chloride concentration of approximately 10,890 mg/L (CH2M Hill, 1987). The 10,000 mg/L TDS boundary occurs at approximately 1,450 feet BLS.

 Injection at this site started in August 1987. In general, the plots for TDS, chloride, and TKN are irregular, and it is difficult to see any trends. Chloride values drop from a high of over 13,000 mg/L in late 1987, stabilizing around 10,000 mg/L from late 1988 to early 1990. The values increase after early 1990. TDS data are available only from 1989 to the present. The values peak in late 1989 around 25,000 mg/L, and drop off to about 19,000 mg/L in mid-1991. The shallow monitor zone water-quality data do not show any significant trends. In this area available data cannot be used to determine conclusively if vertical migration of injection water has occurred.

 West Melbourne

 The West Melbourne injection well has a total depth of 2,409 feet BLS in the Oldsmar Formation. The confining interval, as defined by CH2M Hill (1986), extends from 1,600 to 1,980 feet BLS in the lower Avon Park Formation. The injection zone extends from 1,980 to 2,409 feet BLS with the main injection interval extending from 2,000 to 2,200 feet BLS in the Oldsmar Formation (Appendix A7). The monitor zones are a part of the injection well annulus, with an upper zone from 1,234 to 1,306 feet BLS, and a lower zone from 1,410 to 1,450 feet BLS, both in the middle Avon Park Formation.

 From 1,600 to 1,840 feet BLS the confining zone as defined by CH2M Hill is dolostone with porosity ranging from five percent to 30 percent,