Folder_0047

NYC 9/11 Public Portal Document

MEMORANDUM

To: Michael Anton

From: Geoff Ryan

Date: November 1, 2000

Re: Delaware Aqueduct Information

Tim Minton interviewed Comm. Miele on Tuesday morning about the leaks in the Delaware Aqueduct. With the encouragement of Robert F. Kennedy Jr., he is trying to blow the story out of all proportion, make it seem like disaster is imminent, and contend that we have been negligent or worse in hiding the story from the public.

Water loss from the aqueduct has been evident since the aqueduct went into service in the in 1950s. There are two leaks the Aqueduct; both west of the Hudson River, one in Roseton, the other at Wawarsing. Consultant's analyses show that between 1995 through 1999 leakage has ranged between 14 mgd and 34 mgd, with isolated incidents as low as 13mgd and as high as 38 mgd. Leakage quantity is directly related to the amount of flow in the Aqueduct, i.e., when flow is near or above 900 mgd the leakage tends to be in the upper 20s and lower 30s; when flow is in the 600-700 mgd range, the leakage is in the lower 20s and upper teens. Leakage rates have been relatively consistent. • The leak represents approximately 3.2% of flow in the Delaware Aqueduct; 1.6 % of the average consumption from the whole Water Supply System (1.3 billion gallons a day). At 30 mgd, it is the equivalent of 30 fire hydrants being wide open for the day. Estimated total leakage (including Delaware Aqueduct) from the aqueducts and tunnels outside of the City amounts to approximately 56/0. By comparison, the Los Angeles System may lose as much as 25% of its supply. • The leakage rate for the 6,181 miles of distribution pipes within the city, and separate from the aqueduct leaks, is approximately 5%. • In a survey of cities around the: country during the.late 1990s, the average leakage rate was approximately 20%. • Structural Risk Analysis indicates no evidence that tunnel is in imminent danger of failure. • Starting 11/28, DEP will repair a gate valve at Shaft 6 on the Aqueduct. This involves a team of technicians working in water 700 feet'below the surface. That repair will allow DEP to de-water the aqueduct. De-watering will enable us to inspect the aqueduct with a remotely operated submersible vehicle, currently under construction at Woods Hole Oceanographic Institute, in 2001. At the same time, other investigations and tests will continue. • DEP has contracted with consultants for an evaluation of options to maximize other existing sources during any shutdown for repairs. Possibilities include: up to 100 mgd from wells in the Jamaica System; increased flow from Croton System from 240 mgd to 290 mgd (after filtration plant is on-line); pumping up to 225 mgd from Croton Falls & Cross River reservoirs; tapping into Brooklyn-Queens aquifer. • DEP has also contracted for preparation of specifications for materials, equipment and a repair contract in the unlikely event of a tunnel failure. Feasibility studies are also underway for constructing a third crossing of the Hudson River.

NYC-WTC 000137704