NYSDEC letter re: Con-Edison release report at 7 WTC substation,

NYC 9/11 Public Portal Document

Fa.-.: No'/ 3 1539 15; 15 p. eg P.6 NOV 21 '01 06'02FN R & D

The groundwater monitoring wells will be constructed in accordance with Addendum n, Groundwater Monitoring Well Installation Guideiines, and the American Society of Testing Materials (ASTM) Standard Practice D-5092, Standai'd Practice for Design and Inslallaiion of Groundwater Monitoring Wells in Aquifers.

A 6-inch diameter PVC monitoring well win be installed at each successfully completed boring. However, unforeseen subsurface conditions may necessitate the installation of 4* inch diameter monitoring wells. Each well will be furnished with 13 feet of 0.01-slotted screen, with 10 feet below the water table and five feet above the water table. Clean filter sand will be placed around and above the screened interval. A bentonite seal will be placed above the sand pack interval, and the borehole annulus will grouted to grade with a bentonite/cement slurry, Each well will be fumiKhed. with a flush-mount bolt-down road box and a locking well cap. Each well will be developed by pumping and surging following installation. Con Edison expects that the wells will be developed using a vacuum truck to be provided by the EPA. Con Edison requests that NYDEC coordinate the EPA involvement for the monitoring well development.

Groundwater samples will be collected from each monitoring wcU where free product is observed, Soil samples will not be submitted for analysis if free product is identified in the groundwater. If no free product is observed in the groundwater, only soil samples will be collected and they will bo collected from above the water table or at the depth with most visual contamination. The table below illustrates each scenario with the necessary protocol for sampling.

___________ Scenario _____ ____ _____ Sample Submittfll Protocol Evidence of soil contamination. Free Only groundwater sample submitted for product io groundwater______ ______ analysis ______ _ Evidence of soil contamination. No free Only soil sample submined for analysis product in goundwater_________ No evidence of soil contamination. Free Only groundwater sample submitted for product in groundwater_____ analysis No evidence of soil contamination. No free Only soil sample submitted for analysis product in groundwater

Samples will be submitted to Con Edison’s Chem-Lab for both fingerprint analysis (Oil ID) and PCB content. Con Edison expects that wells and/or manholes observed to contain free product will be pumped out by the EPA at an appropriate frequency to facilitate product recovery and that dates, quantitias, and location of product recovered be documented and information provided to Con Edison. Con Edison requests that NYDEC coordinate the EPA Involvement with the pumping of free product.

INVESTIGATION DERIVED WASTES

Investigation derived wastes such as soil cuttings, decontanunation water, disposable poreonal protective equipment (PPE), etc, will be placed into a 55-gallon drum provided

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