Stormwater Isn't Clean Water
In my blog entry yesterday I talked about IDDE (not IEDs) as a requirement under the new MS4 General Stormwater Permit. While I've been brushing up on this MS4 permit, I've been writing a fact sheet on wastewater treatment in Minnesota and learned that it's not uncommon for wastewater to mingle with stormwater. (Very) interesting facts about wastewater:

• Domestic wastewater is 99.9% water, but it contains enough harmful material to damage the quality of ground water and surface water.
• Normal domestic wastewater is grey, resembling dirty dishwater
• Metals, organic pollutants, sediment, bacteria and viruses can all be found in wastewater
• It’s estimated that 39 percent of Minnesota’s backyard septic systems are not adequately treating wastewater. An estimated 12 percent (64,000) are classified as ‘imminent threats to public health and safety’

This is all to say that when sewer pipes are illegally (and sometimes mistakenly) connected to storm sewers, raw sewage trickles untreated directly into rivers and lakes. The job of Illicit Discharge, Detection and Elimination is to track down these connections. What's interesting is that testing water at outlets can sometimes 'fingerprint' the source.