The City of Madison Engineering Department announced publicly on Tuesday Feb. 26, 2013, that it will hold a public information meeting next Thursday March 7 at 6:30 pm in Predolin Hall, Room 114 of Edgewood College. The purpose of the meeting is to “describe their proposed trial application to the pond at Glenway and Monroe, with the goal of removing phosphorous from the water.” See official announcement below that went out to neighborhood association list serves and was posted on the web page of Alder Sue Ellingson.
ALUM APPLICATION TRIAL
Thurs 3/7 – 6: 30 pm
Predolin Hall Room 114, Edgewood College
City Engineering will describe their proposed trial application of alum to the pond at Glenway and Monroe, with the goal of removing phosphorus from the water.
Details of what City Engineers are proposing are sketchy. We do know that the trial application would be made to Marion Dunn Pond in the University of Wisconsin-Madison Arboretum at Glenway and Monroe Street. Sources familiar with the thinking of City Engineering and their consultants Montgomery and Associates tell me that alum would be added to the inflow of Marion Dunn Pond (Monroe Street side of pond), and that monitoring samples of water would be taken at the outflow (marsh and lake side of the pond). Beyond that not much is known, as myself and others in the Lake Wingra Watershed environmental community, and neighborhood associations have not yet seen the written proposal, as of Thursday afternoon February 28, 2013.
A search yesterday (Feb. 27, 2013) of the City of Madison Engineering Division web page using the terms “alum application trial” and variations, did not turn up anything. An inquiry to Alder Ellingson has so far resulted in a referral to Greg Fries, of the City’s Engineering Division for more information. At the time this is written I have not heard back from Mr. Fries.
If you’re like me you are probably wondering: What is alum? Why would it be applied to a water body? What problem (s) is its use intended to address? And what are the expected results?
First, according to Wikipedia: Alum (pron.: /ˈæləm/) is both a specific chemical compound and a class of chemical compounds. The specific compound is the hydrated potassium aluminium sulfate (potassium alum) with the formula KAl(SO4)2·12H2O. More widely, alums are double sulphate salts, with the formula AM(SO4)2·12H2O, where A is a monovalent cation such as potassium or ammonium and M is a trivalent metal ion such as aluminium or chromium(III).
Alum is used for a variety of purposes including industrial, cosmetic, culinary, and as a flame retardant, and, according to Wikipedia, since at least Roman times as a water purifier. Water purification is apparently the intended use this time to force phosphorous to drop out of the water and settle on the bottom of the pond where is will be out of circulation, until the pond is dredged. In this way, alum is used as a chemical flocculant where the chemical bonds with suspended particles–soil, sand, and sediment, all of which have phosphorous attached to them–allowing them to flocculate or stick together. The by-product is called “floc”.
The specific alum additive to be used is potassium aluminum sulfate and the chemical interactions in the pond will, according to a local lake expert who has studied Lake Wingra extensively, result in an increase in sulfate (SO4). His concern is what will happen to the “floc” and what will be its impact (s) on the biota if alum is used widely and over the long-term.
This is one legitimate concern and there are many more, large and small. We will list a few of the questions that should be asked of City engineering staff next Thursday.
We’ll get to the questions, but first, a cautionary note: do not be seduced by the temptation to tinker with this engineering proposal. The tinkering approach is a siren’s song and a distraction. This is because it’s not possible for the City of Madison to engineer its way out of the morass of storm water problems that were created by its past engineering “fixes” and “solutions”. These engineering fixes failed because they addressed symptoms and not the underlying cause. The alum application trial is a good case in point because it too is directed at a symptom, not the fundamental problem. The fundamental problems that should be addressed and remedied are how the City inadequately prevents or reduces storm water runoff, and how it inappropriately manages the current high amount of storm water into Lake Wingra.
To storm water engineers and limnologists, phosphorous is a problem in lakes because they see it as a cause of eutrophication or over-supply of nutrients that promote weed growth. True, weed growth does result from phosphorous overloads, but phosphorous is a symptom of a more fundamental set of problems with how we use the urban landscape. And, if we back up a bit more we see that storm water itself is not a cause but rather a symptom of this same abuse of the urban landscape.
Aldo Leopold talked about urban landscape problems resulting from the engineering approach years ago in a little essay called “Engineering and Conservation” (1938, pages 249-154 in “The River of the Mother of God and Other Essays by Aldo Leopold, edited by Susan L. Flader and J. Baird Callicott.” Leopold said, in part:
“I mention last what to me seems the least discussed but most regrettable instance of short-sighted engineering–the wholesale straightening of small rivers and creeks. This is done to hasten the runoff of local flood waters, and of course aggravates the piling up of flood peaks in major streams. It is, on its face, a process of pushing trouble downstream, of seeking benefit for the locality at the expense of the community. In justice the stream-straightener should indemnify the public for damage; in practice I fear the public may at times subsidize him with relief labor.” Leopold goes on to say, “The interplay of engineering and ecological evils is an insidious thing.”
Just take a look at Marion Dunn Pond (below) to see for yourself that trouble has indeed been pushed downstream. We blogged about this in 2012 under the entry “What’s Going In Scummy Pond?”
This is the only storm water pond in the Lake Wingra Watershed with a chronic and persistent scum layer, indicating that something unique to the small sub-watershed that drains into the pond could be responsible for the algae growth.
Like all good engineering proposals the alum treatment proposal should be carefully considered and evaluated both on its own merits, and as a component of a larger package of upstream remedies that deal with the ultimate causes of phosphorous loads. These causes include the application of street sand in winter, soil erosion from commercial and residential construction projects, erosion from the City’s own storm water runoff channels on public property, an insufficient number of rain gardens, and missed opportunities around the watershed to infiltrate storm water, among others.
Here are a few questions that City Engineering staff should be asked on Thursday. The list is partial and a result of my curiosity and that of others I have spoken with and heard from:
What water body, or bodies, are the ultimate, intended target(s) of the alum application program?
If it isn’t the Marion Dunn Pond and Lake Wingra, why do the trial there?
Why is a local demonstration site even needed in the first place if it’s not the ultimate intended installation site?
How about a trial at a less environmentally sensitive location, say the West Towne retention ponds?
How sustainable is the use of alum as a method for treating storm water, say compared to other methods?
Is the proposed alum application a one-time use or intended to be applied for longer periods?
Have the upstream contributors to the algae growth and phosphorous loads in Marion Dunn pond been identified? In what ways are these problems being addressed upstream?
What community level concerns have been identified and how does this project address them? Short term or long-term?
What is the ultimate purpose of the trial: the effectiveness of removing phosphorous? or is it the method of alum application that is being tested?
Is the trial intended to lead to more widespread applications in Madison?
What outflow data will be collected?
Will the public get the data in real-time?
How will unintended negative impacts to Lake Wingra and beyond be identified unless the entire biota/ecosystem is sampled?
In addition to phosphorous removal, what impact will alum have on total nitrogen (and other forms of nitrogen), heavy metals? and fecal coliform bacteria?
Are there contaminants in the alum and if so what are they? How will their possible impacts be avoided, minimized, or mitigated, in that order?
What are there unintended negative impacts (side effects) of alum applications? How will these unintended negative impacts be avoided, minimized, or mitigated, in that order?
How will Lake Wingra benefit (or not) from the alum application? How will the benefits/detriments be measured and tested?
Coverage of this topic will continue and be updated if, and when, the City Engineering Division presents us with a copy of its proposal. We will also report on the March 7 public information meeting.