Removing Bacteria from Stormwater
Removing Bacteria from Stormwater
(OP)
Is it practical to remove bacteria from stormwater runoff, given the following conditions:
The runoff is from a proposed 7-lot, rural residential development;
The site soils are primarily clay, with a very high groundwater table (i.e., no infiltration);
The runoff drains to a county ditch, which leads directly to salt water.
Stormwater carries a variety of pollutants.
Water quality sampling by the State Dept of Health has identified the immediate area as at risk to shellfish harvesting, due to this bacteria;
The County is responsible for ensuring there is no further degradation of the saltwater.
Typical stormwater treatment techniques (biofilters, wet ponds, even Stormfilters, etc.)do not directly address bacteria removal.
So, short of the developer installing a small wastewater treatment plant, is there any way to effectively treat this runoff?
The runoff is from a proposed 7-lot, rural residential development;
The site soils are primarily clay, with a very high groundwater table (i.e., no infiltration);
The runoff drains to a county ditch, which leads directly to salt water.
Stormwater carries a variety of pollutants.
Water quality sampling by the State Dept of Health has identified the immediate area as at risk to shellfish harvesting, due to this bacteria;
The County is responsible for ensuring there is no further degradation of the saltwater.
Typical stormwater treatment techniques (biofilters, wet ponds, even Stormfilters, etc.)do not directly address bacteria removal.
So, short of the developer installing a small wastewater treatment plant, is there any way to effectively treat this runoff?





RE: Removing Bacteria from Stormwater
RE: Removing Bacteria from Stormwater
And, unfortunately, infiltration is not an option (high groundwater and tight soil).
RE: Removing Bacteria from Stormwater
To answer the initial question, probably not practical.
a) it would be very costly
b) probably be ineffective in reducing the bacteria
c) the site that is generating the bacteria should be responsible for cleaning it up...
RE: Removing Bacteria from Stormwater
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Multiple studies have documented that residential developments can (and usually do) produce significant amounts of fecal coliform and other bacteria. This shuts down shellfish harvesting (and the livelihoods of the shellfishermen) as the shellfish are unsafe to eat from such exposure. Every "little" impact adds to the total. I suggest infiltration to the maximum amount practical (understanding your comments about the site limitations) and maximizing runoff detention exposure to sunlight. You might consider a brackish treatment marsh. There are lots of documents available to guide you on this. I suggest starting with the Center for Watershed Protection (www.cwp.org) and your state's Sea Grant program (www.seagrant.noaa.gov).
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tsgrue: site engineering, stormwater
management, landscape design, ecosystem
rehabilitation, mathematical simulation
http://hhwq.blogspot.com