NYC-WTC_000208633

NYC 9/11 Public Portal Document

March 11, 2002

Ms. Sophia Rabich New York City Department of Environmental Protection B urean of Wastewater Treatment Division of Pollution Prevention & Monitoring 96-05 Horace Harding Expressway, Floor Corona, NY 11368

SUBJECT; WORLD TRADE CENTER AND PATH TUNNEL E RECOVERY NYCDEP FILE CASE NO. C-3192

Dear Ms. Rabich;

I have received some questions in response to the Amendment to Permit #C-3192 from the DDC’s contractor, Moretrench American Corporation and their laboratory, Severn Trent Services. My understanding of the permit leads me to believe that sampling is cunently being done correctly; however I want to be sure you agree.

They have analyzed the samples for chlorodifluormethane since they state that a standard for chlorofluormethane could not be obtained. Additionally, the laboratory is using EPA method 608 to analyze for PCBs. However, the laboratory explains that results for this method are reported in parts per billion (ppb) as opposed to parts per trillion (ppt). The minimum detection level (MDL) for Aroclor is 0.065 ppb. However, 0.065 ppb is equal to 65 ppt, which is the detection limit you have requested.

Please contact me at your earliest convenience if you do not agree that the currently sampling analyses are appropriate. Thank you once again for your assistance with this matter of mutual concern.

Veiy truly yours,

Bernice R. Malione Supervisor, Permits & Govemmentai Approvals Environmental Engineering

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CITY_21MC100_003262809

NYC-WTC_000208633