148 organic pumps in the New Orleans area being worked, with an average of 26 permanent pumps operating, pumping 9,125 cubic feet per second (258 m³/s) and 39 portable pumps were operating, pumping 723 cubic feet per second (20 m³/s). In addition, nine of 26 existing pumps in Plaquemines Parish reported operating at 1,360 cubic feet per second (39 m³/s). The equivalent to an Olympic-sized swimming pool was being drained every two seconds. Final critical breach closed The fourth and final critical breach in the Orleans and East Orleans areas was closed. A roadway had been built, at the rate of 500 feet (150 m) a day, from the 17th Street Canal work area to reach the London Avenue Canal breach. From the London Avenue west side breach, the road was built to the second breach area at Mirabeau Road. As at the 17th Street Canal, at the London Avenue Canal the flow from Lake Pontchartrain into the canal had been cut off. Corps contractors drove 150 feet (50 m) of steel piling across the canal to seal it. Texas Army National Guard Chinook and Blackhawk helicopter crews had placed an average of 600 7,000-pound sandbags each day into the breaches. Depending on the helicopters lift capability, Corps riggers averaged one to three hookups every two minutes during daylight hours. Sandbagging operations ran 24 hours for ten days and, with the breaches complete, were halted September 10. Several crane barges were also used to place sandbags and gravel, and other barges were used to haul equipment, pumps, generators and people to sites. By Sunday, September 11, 2005, the number of operating pumps had been raised to 74 of 174, with the high capacity Pumping Station 6 expected to be returned to service within days. Officials lowered the estimated maximum amount of time required to unwater New Orleans to 40 days, or late October, 2005. By September 12, 2005, water had overtopped the temporary breach closure at the London Avenue Canal because of operations at Pump Station 3. This caused the canal to rise faster than the temporary pumps at the end of the canal could drain. Operations at Pump Station 3 were immediately stopped and a few sheet piles were removed to allow the canal water level to equalize. September 13 For nearly a week, Plaquemines Parish floodwaters were receding naturally through three breaches and a deliberate notch. The unwatering