A septic system includes a septic tank and a drain field.
The tank is designed to provide a place where large solids can settle and
be decomposed by microorganisms (scum layer). The drain field removes fine
solids and accompanying bacteria (sludge layer). Effluent from a septic tank
contains solids, phosphorus, nitrogen, chloride, bacteria, viruses and organic
chemicals. For this reason, it is illegal to discharge a septic tank directly
into a tile line or other surface water. Non-complying septic systems within
SMC Watershed are either tied directly into tile lines, therefore bypassing
the treatment phase all together, or leaky, by which poor construction allows
untreated wastewater to seep directly into groundwater. Through the improvement
plan described above, it is estimated that 13% of the phosphorus load in the
watershed could be reduced.
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The
Nicollet County Environmental Services Department (ESD) has estimated that within
SMC Watershed, 61% of the private septic systems are not in compliance with
public health regulations. Of the 157 households in the SMC Watershed, 96 are
considered to be "imminent threats to human health," by the SMC Watershed
Project report.
The cost to remediate these failing septic systems would total approximately
$720,000 (an average of $7,500 per home). While this seems like a large sum
of money for homeowners to voluntarily put forth, complying septic systems are
required for any future resale of a home. $550,000 in State Revolving Funds
has been allocated to help establish low interest loans as an incentive to homeowners
to upgrade in the next 1-2 years. Through this program, over 70% of the imminent
threat will be reduced.