OUR ENGINEERS has analyzed the reports that Denver has to make to the EPA, about pollution it intends to dump into the South Platte River. You will be shocked: (POLREP #10:http://tinyurl.com/jluph29 ) . "The PELs are typically around 300 times higher than the corresponding in-stream standard, which would normally control the discharge concentration. 2. The absolute concentration allowed by the PELs can be staggering.      - Zinc can kill fish at 289 ug/L, but the PEL discharge "limit" is 93,000 ug/L. This is about the zinc concentration of acid mine drainage!      - Sulfate causes diarrhea in humans at 250 mg/L, yet the PEL allows discharge at 100 times that concentration, or at least 10 times the concentration in the Gold King spill." READ MORE THEN EMAIL THE EPA AND SAY "STOP THE PLATTE TO PARK HILL DRAINAGE PROJECT UNTIL YOU HAVE ANSWERED OUR QUESTIONS" : SHAUN MCGRATH:shaun.mcgrath@epa.gov AND DANIA SINNER: dania.zinner@epa.gov In POLREP #10 the team selected Preliminary Effluent Levels (PELs) to control the quality of the discharge into the river of water removed from the aquifer under the Vasquez - I-70 Superfund site to allow construction of the new outfall. The respondent's engineer says that " Respondent (the City and County of Denver) examined the PELs and determined them to be more reasonable than discharge limits in the General Discharge Permit, so elected to apply for an IDP [Individual Discharge Permit]." (emphasis added) So I took a look at the appendices that supported the PELs, and they are pretty horrifying. Here's a comparison table showing the "more reasonable" PELs versus the relevant stream and drinking water standards, which would normally form the discharge limits. SEE BELOW: No apology for the table being a bit dense, but consider a few things: 1. The PELs are typically around 300 times higher than the corresponding in-stream standard, which would normally control the discharge concentration. 2. The absolute concentration allowed by the PELs can be staggering.      - Zinc can kill fish at 289 ug/L, but the PEL discharge "limit" is 93,000 ug/L. This is about the zinc concentration of acid mine drainage!      - Sulfate causes diarrhea in humans at 250 mg/L, yet the PEL allows discharge at 100 times that concentration, or at least 10 times the concentration in the Gold King spill.      - The organics are also huge: the total concentration of this cocktail of (mainly) hazardous chlorinated hydrocarbons is 1,458,000 micrograms per liter, where the typical drinking water standards are in the 5 micrograms per liter range. The good news is that most of these organics are volatile, and degrade in ultraviolet light, but not quickly enough to protect Globeville or Elyria. No surprise there. 3. No question that the PELs are "more reasonable" from the vantage point of an organization - here the City and County of Denver, aka "us" - that is looking to get rid of as much contaminant as possible for minimum cost, by dumping it in the river. Is it "more reasonable" for the river than the other standards? Not so much. Just don't expect fish to live in the water, and don't let the local kids play in it or drink it. 4. The final issue is that the regulations may require consideration of a mixing zone in the river, where downstream conditions and uses (like swimming, fishing, drinking water intake) can be considered. This study was not required to do a mixing zone study, so the City can take "100% credit for the assimilative capacity of the river." That is it can pollute to the limit. And until the mixing has taken place - typically over a mile or more - there are locations in the river where the concentrations are closer to the very damaging PELs than they are to the stream Table Value Standards. And where is that? Right at the outfall park, of course, a magnet for human contact. Please don't let your kids swim in or ingest this stuff.  Why the disparity between "permissible" and "safe" discharge limits? The PELs are computed to be equal to the concentration which, if present in the discharge, would be sufficient to raise the entire river to the regulatory standard (here the "stream" value).  As the flow in the river is much greater than the dewatering flow (by a factor of  350:1 even at low flow), that dilution is the "solution" to a lot of pollution.    But if the discharge contained the PEL concentrations, then no other addition of those chemicals to the river could take place, upstream or downstream for a significant distance. And finally there is an "antidegradation" requirement in the regs. However, if the dilution is greater than 100:1, by regulation it does not have to be considered, so it wasn't. Thus the City can degrade as much as it likes, which turns out to be a lot. This is outrageous for us to be doing to the river, to its ecosystem, and to the people who come into contact with the river. All in the name of saving a few bucks by essentially avoiding treating the groundwater taken out of this Superfund site to allow the mega-outfall to be constructed before flushing it into the river.