Aug 16
2009

I have recently had the opportunity to extend my modeling capabilities by learning SWMM5.  The training that I went through was a web-based course offered by Computational Hydraulics International (CHI), who offers their own SWMM software toolset that goes by the name of PCSWMM.  The training included the following SWMM capabilities and uses:

-Hydrologic routing using RADAR, rain gages, or synthetic events.

-Steady state and dynamic  hydraulic modeling of piped and open channel networks.

-Event-based and continuous modeling.

-Detention pond design.

-Land use – based water quality modeling and evaluation of best management practices (BMPs).

-Sanitary sewer dry weather flow (DWF) and rainfall derived inflow and infiltration (RDII).

-Sensitivity, calibration, and error analysis.

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Jul 2
2009

And now for some local news.  The main source of drinking water in Raleigh, Falls Lake, has had some problems with nutrient levels and algal blooms.  The Neuse River, on which Falls Lake is located, already has a set of rules to regulate nutrient levels in stormwater runoff.  However, due to the sensitivity of the problems at Falls Lake, a combination of state and local officials in Wake County are pushing a plan for a speedier cleanup of the lake through the State Legislature.  This has great potential to affect Durham County, however, as much of the pollution appears to originate there.  The likely result would be an accelerated and expanded plan of retrofits to existing development to treat stormwater runoff.  It is also a potential double whammy for Durham too, as Jordan Lake, to its south, is currently undergoing development of a similar plan.  The difference for Durham, however, is that it uses Jordan Lake as a drinking water source.

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Jun 26
2009

Reuters Media The Supreme Court recently upheld a permit issued under the Bush administration by the Army Corps of Engineers to allow a mining company to dump tailings from an Alaskan gold mining operation into Lower Slate Lake, which is located in the Tongass National Forest.  The Clean Water Act is supposed to prevent such discharges into natural waters, which is essentially what the appeals court had said in its previous ruling that the Supreme Court has now overturned.  Instead, the mining company, Coeur d’Alene Mines Corp, argued that the lake was the most practical and environmentally sound method of disposal.  Though this is likely to kill all aquatic life in the lake, it was argued that the lake could always be restocked with fish and restored once mining operations had ceased.  This claim seems suspicious to me, however, as gold mining operations have usually been associated with arsenic and I would suspect that such high levels would persist for some indefinitely long period of time.  Nonetheless, the 6-member court majority had said that deference must be paid to the “reasonable” decision made by the Corps of Engineers.  Unfortunately, what I read into this description is that one can get away with whatever the regulator can be convinced into allowing, however that might be accomplished.

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Apr 22
2009

FrontlineI happened upon this gem last night.  It is an episode of the PBS news magazine Frontline.  It is a summary of what problems face our waters today.  Primary examples of current threats include nutrients, endocrine disruptors, and PCBs.

Nutrients largely enter our waters from wastewater discharge and stormwater runoff contaminated with fertilizer and agricultural byproducts.  However, combustion byproducts found in automobile emissions also contain nutrients and find their way into open water in significant amounts.  These nutrients cause an explosion of microbial growth, which can reduce dissolved oxygen and kill everything that depends on it in the water, such as fish.  In fact, the problem has gotten so bad that oceanic dead zones have spread across the world.  One of the most famous occurs in the Gulf of Mexico around the Mississippi River delta.  It is in order to stop these occurrences that stormwater best management practices (BMPs) are required as part of most urban development, but agriculture is still largely unregulated.

Endocrine disruptors are chemicals that mimic hormones in the body.  They are used for this reason in drugs to treat certain conditions.  It also happens to be that certain industrial products happen to have this property.  A good example is bisphenol a (BPA), which is found in various plastics.  It happens to be used in many drink containers and, for this reason, public pressure has forced many baby bottle makers to go BPA-free.  The fear in this case is that boys will be femenized, possibly to the point of having fertility problems.  When endocrine disruptors make it into the wild, it has been known to make organisms that are genetically of one sex to develop as the other.  As far as I know, there is no current regulation of endocrine disruptors in our water (drinking, waste, or natural).

Polychlorinated biphenyls (PCBs) are an example of a kind of toxic  and possibly carcinogenic chemical that is also very persistent as they do not readily degrade.  PCBs are usually associated with old electrical facilities.  Because they are so persistent, PCBs can accumulate over time in animals from both what they eat and their surroundings.  Exposure can get worse from generation to generation as the PCBs can be passed from mother to baby.  The effect is that an entire population could potentially be killed by PCBs.  I have actually had the occasion to work on the design of road crossings of a stream contaminated by PCBs.  It was necessary to span the stream so as not to disturb it and potentially release any PCBs that might be contained in the soils and sediment.  The site has been designated a superfund site, though no cleanup has yet occurred.

If you watch the following video, it will take you through the history and the process by which Chesapeake Bay, Puget Sound, and other waters have been contaminated.  It will also document the effects this has had on the ecosystem and some of the efforts that have been made to mitigate them.  One obvious take-home message is: be careful where you fish.  Another one might be to be careful what you drink.

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