There was a uniform rental company on the south shore of Long Island- its gone now. They would provide uniforms for businesses all over the island. They would deliver the clean uniforms and they would pick up the dirty uniforms , clean them and deliver again.

They had two ways to clean the clothes- laundering with soap and water and dry cleaning. I used to think- what the heck is "dry" cleaning? Is it dry? Well, after visiting over 350 dry cleaners, I am very qualified to explain it--you may know how a regular washing machine works- water and soap, wash the clothes, etc etc..  Well, a dry cleaning machine works the same except instead of water, they use a liquid chemical called perc, or perchloroethylene, or tetrachloroethylene- it's a "wet" process- they just call it dry because they don't use water!

Also, the latest dry cleaning machines have the washer and the dryer in one machine (the old dry cleaning machines had separate washers and dryers- just like regular machines).

But I digress. So this place was in business since the 1950's- cleaning lots of uniforms. They had storage tanks for the Perc. The tanks had leaks, they had spills when the perc was delivered. They had perc in their cesspools. They had a lot of contamination of the soil and the groundwater which was only about 10 feet below grade.

Perc is a hazardous chemical that causes cancer- this site was listed as a New York State Inactive Hazardous Waste Disposal Site (the last time I checked, 18% of the state superfund sites on Long Island were dry cleaners)

The following pictures show how they cleaned up the soil by installing a soil venting system. A soil venting system is like a giant vacuum cleaner with 10 suction hoses. The suction hoses are buried in the ground and they suck the perc vapors out of the soil.

After the perc vapors are sucked out of the ground, they are pushed through carbon filters. The perc vapors stick to the carbon granules in the filters. After a while, the carbon can't absorb (or "adsorb") any more perc and it has to be replaced with clean carbon. The dirty or "exhausted" carbon can be disposed of as hazardous waste or it can be sent to a carbon recycling facility where the perc is steamed out of the carbon, and then the carbon can be reused and the waste perc is disposed of.

The pictures also show how they installed monitoring wells so the groundwater could be tested for perc. There is also a map showing how far the perc moved in the groundwater.

Collecting a groundwater sample.
 
 

Soil samples from the monitoring well drilling.

On site, they also installed "sparging" points in the groundwater. Sparging is like when you put a drinking straw in your chocolate milk and you blow bubbles. Compressed air is forced into the groundwater and the bubbles make the perc in the groundwater evaporate and leave the groundwater and move up into the soil, where the vapors are sucked up by the soil venting system!

Off site, the groundwater was pumped up and put through an air stipping tower. An air stripper mixes the water with lots of air and causes the perc to evaporate. ( I don't have a photo of the air stripper at this site but I have photos of other air stippers on this web site-see the more photos section).