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In 1970 each person in south Dade County generated about one ton of solid waste and about 40,000 gallons of liquid waste. Disposal of these wastes is both complex and costly.

The liquid waste--45 million gallons of sewage per day--is disposed of primarily through drainfields and ocean outfalls. About 32 percent of the population of Dade County is served by more than 172,000 individual septic tanks. Most of these are in the south Dade area. As a result, much of the shallow ground water underlying the urbanized area has been contaminated, especially by nitrates. Recent studies, however, have found no evidence of contamination by pathogenic viruses.

More than half of the sewage from Dade County is disposed of through ocean outfalls. This image is from the National Aeronautics and Space Administration [larger image]

More than half of the sewage from Dade County is disposed of through three ocean outfalls. An additional 13 per cent is discharged into lakes and canals or into seepage pits. Of the 29 sewage treatment plants serving the south Dade area, only one--the Key Biscayne plant-- discharges to the ocean. Two plants discharge effluent directly to the so-called "boulder zone" of the deep Floridan aquifer. Currently, about 3 mgd of treated sewage from the Coral Gables plant and about 1.5 mgd from the Kendall Lakes plant are being injected. There is much controversy over the efficacy of ocean outfalls, the use of septic tanks, and the need for tertiary treatment. Deep well injection is a controversial method of waste disposal and is being carefully monitored.

There are more than 172,000 septic tanks in Dade County. Most of these are in the south Dade area. [larger image]

Some sewage effluent is disposed of by deep-well injection. 17/ [larger image]

In 1970, about 30 percent of the 400,000 tons of solid wastes generated in the south Dade area was incinerated; the rest was disposed of in dumps and landfills, mostly outside of the area. There are 18 dumps and landfills in Dade County; of these, 8 are in the area. Proper operation of sanitary landfills is inhibited by the thin soil and high water table. Therefore most landfills are basically open dumps which burn periodically and are eventually covered with a veneer soil. They are sources of pollution to the Biscayne aquifer as the heavy rainfall leaches contaminants from the wastes and transports them through the permeable limestone to the water table.

Solid wastes are disposed of in both open dumps and sanitary landfills. [larger image]		Proper operation of sanitary landfills is inhibited by thin soil and high water table. [larger image]		Twenty-nine sewage treatment plants serve the south Dade area. [larger image]

At the present time, Dade County does not have any formal recycling projects. One pilot project, however, in Coconut Grove is aimed at reducing the volume of solid waste by composting. Citizens' efforts, mostly under auspices of local conservation groups, have been limited and sporadic.

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