The $1.1-billion North River Wastewater Treatment Plant was built on a $232-million, 32-acre concrete platform, 750 ft wide and 18 blocks long. It stands on 2,400 concrete-filled steel caissons, each 42 in. in diameter, which are set into rock as deep as 250 ft below water level. The caissons, fitted with cutting edges, were driven through organic silt and glacial till and then drilled into rock. After a grout seal, they were dewatered and filled with 4,000-psi concrete (ENR 6/21/84 p. 56).

Contractor for the platform was a joint venture led by Perini Corp., Framingham, Mass. A joint venture headed by Tippets-Abbett-McCarthy-Stratton, New York City, designed the platform and the treatment plant. The platform was completed in 1978. The tight site required contractors to use three 300-ton, barge-mounted cranes set up along the platform perimeter to lift the roof's 3,000 concrete slabs and concrete arches for the plant's facade. More than 40,000 cu yd of concrete were needed to complete the project.

Primary treatment began in 1986 and secondary treatment in 1991. An activated-sludge secondary treatment plant that can handle up to 340 mgd is contained within a windowless building covering the entire platform. The normal 170 mgd of effluent is disinfected and released to the Hudson. Dewatered sludge is made into fertilizer.

The 28-acre, $119-million rooftop Riverbank State Park is home to three pools, an amphitheater, athletic center, skating rink, restaurant and sports field. Walls 50 to 65 ft high provide a base for the park, which carries enough soil to support trees, bushes and grass. Fill depth is from 5 in. to 3 ft. In some areas, bottom layers of extruded polystyrene replace soil to reduce the load. Utilities are electrically heated to protect them from feeze-thaw cycles. The park's designer was Richard Dattner Architect and its general contractor was Antonio Marino Construction Corp., both of New York City. The plant was later revamped to mitigate odor problems.

NEWS IN BRIEF 1986-1988

The Chernobyl Reaction
The severe core meltdown and violent explosion of gases on April 26-27, 1986, inside the Chernobyl reactor station in the Soviet Union was triggered by a serious loss-of-coolant to the 1,000-Mw RBMK, a high-power, pressure-tube reactor. ENR reported that a drive for low-cost power may have been the downfall for the Chernobyl plant. Soviet nuclear plants, including the one in Chernobyl, were designed to use the more efficient, though combustible, graphite moderator. They did not use reinforced concrete containment, except on the sophisticated refueling equipment housed above the core, which enabled refueling without shutting down the reactor. "Western engineers generally gave Russian nuclear designers high marks. But the design of the RBMK plants bears the mark of a political influence" (ENR 5/8/86).

Japanese Firms Blacklisted
The House of Representatives voted overwhelmingly to ban Japanese firms from federal public works contracts for fiscal 1988. The chairman of the Government Operations Committee claimed that Japanese firms performed at least $100 million worth of construction in 1987, including work on the Washington D.C. Metro rail system and the U. S. embassy building in Egypt, while U.S. firms were denied market access in Japan. A spokesman for the Japanese embassy in Washington argued Japan's actions stating that the projects required special underground technology that few American firms were good at and were willing to do (ENR 12/10/87, p. 48).

The Louvre's Great Glass Entrance
French President Francois Mitterrand commissioned New York City-based I.M. Pei & Partners to design the new portal to a $175-million underground reception area of the Louvre museum. Pei said that the entrance to the world's most renowned art museum should embody a majestic air, as it would be the centerpiece of the 750-ft-long, 350-ft-wide courtyard that is flanked on three sides with palaces built by Napoleon III. He designed a 71-ft-high, glass-enclosed pyramid to provide minimum intrusion of space. Its transparency would allow viewing of the palaces from inside the reception area while introducing a lot of light. Opponents of the project called it a high-tech monument of Mitterrand that was out of place among the palaces once occupied by French monarchs (ENR 3/10/88, p. 26).