Official response from Rabbi Joshua Metzger of Chabad in NYC about the recent discovery of the tunnels.

"Every day over 1200 dollars worth of nickels, quarters, dimes, and precious little pennies are dropped accidentally by the people of New York City as they commute to and from work. These tiny gifts just fall into the sewers forgotten and unloved. So we of the Chabad dedicated ourselves to burrowing under the streets to collect these offerings."