What should we do about contaminated sediments in the by day66380


									What should we do about
contaminated sediments in the
Kalamazoo River?

             Duane Hampton
        Western Michigan University
        Kalamazoo, Michigan, USA

              WMU Geotextile
These guys did significant research:
 Cassidy, Kohler, Hudak, & Beck

               WMU Geotextile
 Michigan Dept. of Environmental
  Quality & US EPA for funding us
 Chuck Ide for initial inspiration
 Kevin Kahmark, Brian Bird for the
 Other Geosciences grad students
 Julie Ryan, Stephanie Swart for
  enumerating the biota in sediments
               WMU Geotextile
Contaminated sediments
—a common problem
 Heavy metals (Hg, Pb), PCBs, and other
  contaminants commonly “stick” to fine
  sediments and organic matter in them
 These contaminants are found in rivers,
  wetlands, lakes, harbors, and oceans
 The contaminants resist biodegradation
 They are picked up by benthos and
  passed on to fish & fish eaters (us!)
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    PCBs in the Kalamazoo River
   Most came from de-inking NCR paper
    which was recycled by Allied Paper & by
    Georgia Pacific & other paper mills. The
    PCBs got into Portage Creek & the
    Kalamazoo River. Contamination
    extends from Morrow lake to Lake
    Allegan & to Lake Michigan in 80-mi long
    Superfund area of concern.
                   WMU Geotextile
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Why clean up the Kalamazoo River?
 High PCB levels in fish, mink, & eagles
 Fish are consumed by subsistence fishers
  (migrant workers, Hmong, & poor people)
 PCBs are likely human carcinogens with
  suspected reproductive damages, & impair
  neurological development, etc.
 Kalamazoo River is #4 source of PCBs to
  Lake Michigan. Treaty with Canada says
  we’ll clean up our great lakes some day.
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Fish advisory near Plainwell Dam

                     Let’s see a close-
                      ----------

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            This fish advisory
            was really helpful!
            This sign no longer
            exists. I don’t know
            who removed it.
            Former governor
            Engler didn’t want
            anybody to know
            about the fish
            advisories, and got in
            a battle with EPA.
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Who should eat Kalamazoo River fish?

   Not pregnant or nursing women
   Not children
   Not women who could become
   Men can have an occasional fish, but
    certain species are off limits
   You probably shouldn’t eat any!

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How are people hurt by PCBs in the river?

  100% of the damage comes from
   eating contaminated fish.
  0% comes from drinking PCB-
   contaminated water, because PCBs
   hardly dissolve in water.
  0% comes from swimming, boating
   or wading in the river.

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    Size of the cleanup required
 Nobody really knows because many
  more samples must be analyzed
 5 to 10+ million cubic yards of PCB-
  contaminated sediments, mostly in
  Lake Allegan, Morrow pond & behind
 $50 million to > $2 billion, depending
  on remedial method(s) selected
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    Options for remediating
    contaminated sediments
 Dredging is the usual choice & often is the best
  option for nastiest sediments, but has high costs
  as well as environmental & legal liabilities
 We can bury contaminated sediments using
  impermeable HDPE landfill cover anchored with
  rocks. This cuts off groundwater base flow and
  ends biodegradation of organics.
 We need more & better remediation options!

                      WMU Geotextile
    Why dredging isn’t always good

 It removes only 90—95% of PCBs
 Dredging mobilizes some contaminated
  sediments, increasing exposure risks
 Do sediments and fish have less PCBs after
  we dredge? Wasn’t that the goal?
 Where should we put the dredge spoils?
  Yucca mountain is already taken.

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    What to do with dredge spoils?
 Incineration was most common option, but
  incineration of PCBs creates dioxins
 Turn them to glass or cement. Then where
  does that go?
 PCB-contaminated waste can be sent to
  TSCA landfill$--only 1 in Michigan $$$
 Can we put the dredge spoils in your back
  yard? Only if you’re poor and you can’t
  afford a good lawyer.
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Remediation by capping in place
 Manages  contaminants by
  sequestering them in place, isolating
  them from the food chain
 Capping can be done using ~2 feet of
  sand dumped on top of sediments
 Thinner & thicker caps are used also

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Challenges with sediment capping
 How to place cap while not stirring
  up and mobilizing contaminants?
 How to hold cap against erosion?
 Is there enough depth to allow ~2 ft
  cap in a stream, harbor or lake?
 Will the cap cause biodegradation of
  contaminants to slow down or stop?

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In March 2007, the first step in cleaning up
    the Kalamazoo River was revealed:
 Sediments behind Plainwell Dam will be dug
  out for 1.5 mi upstream and trucked to
  landfill in Kalamazoo. Cost = $21 million.
  This will remove 1.3% of the PCBs.
 $15 million will go toward studying the river
  to better locate other PCB hot spots
 Downstream river reaches will be cleaned
  up later following more negotiations.

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    A new remediation idea is born
 Faced with a big problem, and lousy
  solutions, Chuck Ide asked us to come up
  with a better remediation method.
 Hampton suggested an anchored
  geotextile biointrusion barrier
 Cassidy suggested speeding up PCB
  biodegradation using ozone or BIOX®
 Chuck Ide said combine those ideas

                  WMU Geotextile
What is a geotextile?
   A permeable fabric made of plastic fibers
    stronger and longer-lasting than cotton
    and other natural fibers.
   Many types & uses. Used in or with soils
    E.G.: silt fence, sock around drain pipe
   The geotextile we choose 1. must not clog
   2. must prevent the migration of benthos
    and sediments through it
   3. must allow water to permeate through it

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An anchored biointrusion barrier?
 The goal is to prevent contaminant entry
  to the food chain, eventually ending risk
 Geotextile layer put on hot spots to stop
  benthos from getting in & getting dosed
 The geotextile is held in place by a layer of
  cobbles, gravel and sand, preventing
  erosion of the nasty sediments below
 Base flow can move thru the geotextile

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    Oxidants speed up PCB removal
 PCBs biodegrade verrry sloowly at best,
  not at all when encapsulated in landfills
 Chemical oxidants like ozone & BIOX®
  “tenderize” PCBs by dechlorinating them
  and stimulating microbes to break down
  the daughter products
 Oxidants under geotextile can speed up
  PCB degradation in trapped sediments

                  WMU Geotextile
    The new remediation concept
 Existing methods fail on so many levels
 This method could: decrease risk to
  human health & the environment,
  eliminate disposal of PCB-contaminated
  sediments, enhance degradation of PCBs
  in situ, and lower costs, facilitating more
  actual cleanup

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    But does it work?
 We don’t know yet. That’s why they call it
  research. Please send more money.
 We have concluded separate tests for:
 1. Efficacy of biointrusion barrier
 2. Retention of contaminated sediments
 3. Effectiveness of chemical oxidants

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Gull Creek research site in Oct

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Field test
 Sampled sediments for benthic density in
  four 3 x 3 meter (10 ft x 10 ft) areas of Gull
  Creek in October 2001
 Two of four sampling sites were covered
  with 3 x 3 m geotextile patches (Am 4512)
 Anchored patches with 1 cm sand layer
 Measured benthic density in 4 & 10/02;
  measured velocity periodically

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Steve Kohler sampling benthos

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Dr. Kohler sampling benthos

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Field test
 Sampled sediments for benthic density in
  four 3 x 3 meter (10 ft x 10 ft) areas of Gull
  Creek in October 2001
 Two of four sampling sites were covered
  with 3 x 3 m geotextile patches (Am 4512)
 Anchored patches with 1 cm sand layer
 Measured benthic density in 4 & 10/02;
  measured velocity periodically

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Anchoring geotextile with sand

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Results from Gull Creek field trials
 Benthic density under test patch reduced
  by 94.5% after 6 months compared to
  control, and by 93.1% (other patch) after
  12 months compared to upstream control.
 Both sand-covered geotextile patches
  were colonized by plants that didn’t
  penetrate the patches, making them hard
  to find. The patches emerged unscathed—
  no rips or holes, looking just like new.
                  WMU Geotextile
Summary of lab & field trials
 The nonwoven geotextile used in lab
  and field trials was 93—95% effective
  in stopping biointrusion in sediments
 This anchored geotextile stayed put
  as the bottom of a new living habitat
 The geotextile passes fluid flow but
  filters fine particles

                WMU Geotextile
Options for geotextile barriers
 Install off boats using divers to
  minimize sediment disturbance
 Use layered geotextiles with custom
  amendment(s) held between layers:
  reactants, adsorbents, &/or nutrients
 Concern about biogenic gas bubbles
  can be addressed using geotextiles
  with coarse strips to release gas

                WMU Geotextile
Goals for this technology

 The project team would like to test
  anchored geotextiles at a larger scale
 We predict that geotextiles will be cheaper
  and more effective for shallow hot spot
  cleanup than dredging or sand capping
 Geotextile caps could be combined with
  chemical oxidants & other amendments to
  contain & destroy nearly all contaminants

                  WMU Geotextile
Future goals

   Write a paper about this work.
   Get funding to do actual remediation,
    perhaps on a braided channel of the
    Kalamazoo or another nearby site
    (can you suggest a good site?)
    Cassidy and I want to write an NSF
    proposal this summer.
               WMU Geotextile

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