Juanita Village Site

1
Juanita Village Site

• Groundwater contaminated with PCE

2
Background

• Juanita Village Site, north Kirkland, Washington,
  USA.
• Originally it was a shopping centre in the
  1970s, a dry cleaning shop was present in the
  shopping centre.
• Tetrachloroethylene (PCE) was present in the
  groundwater and the assumption was the soil will
  be contaminated too.
• PCE is a common dry cleaning solvent and the dry
  cleaning shop is most likely to be the source of
  contamination.

3
Background

• PCE is hazardous to health if exposed to a high
  concentration.
• Cause harm to the liver and kidney, also a
  carcinogenic.
• Groundwater was tested for PCE and the maximum
  concentration of PCE was found to be 2600 parts
  per billion (ppb).
• The groundwater plume was found to be under the
  former dry cleaning shop and extends out to about
  700 feet.
• However no PCE was detected in the soil.

4
Treatment

• PCE was removed using a technique called Density
  Driven Convection (DDC).
• Compressed air is injected into the contaminated
  groundwater and vaporises the PCE.
• PCE vapours are vacuumed through a carbon filter.
• The contaminants are then removed from the filter
  and recycled off site

5
Alternative solutions

• Pump and Treat
• Most commonly used
• Using well to pull contaminated water from
  underground, for treatment above ground
• Drawbacks
• Shown to be inefficient
• Have little impact on environmental clean-up

6
Alternative solutions

• Bioremediation
• Using of micro-organisms such as bacteria to
  transform PCE into harmless chemicals such as
  carbon dioxide.
• Drawbacks
• Contaminants may transformed to more hazardous
  form
• Groundwater flow induced
• Very high contaminant concentrations may be toxic
  to micro-organisms

7
Alternative solutions

• Phytoremediation
• Uses plants to take in PCE through their roots as
  they absorb water
• Cost-effective
• Drawbacks
• Slow process
• Roots of plant cannot reach deep underground water

8
Conclusion

• Treatment lasted 18 months
• The DDC treatment removed around 300lbs 136kg
  of PCE from the groundwater
• No PCE contaminated soil was ever detected around
  the site
• The site have to be monitor for a further 12
  months after the clean up operation