Hudson River Park

"The best landscaping the city has seen in a long, long time," is how one jury member described Hudson River Park.

The $46 million project that will bring 550 acres of park space along 5 mi. of Manhattan's West Side stretching from Battery Park City to Riverside Park.

The first phase of the project, referred to as Segment 4, was recently completed. It runs from Barrow Street to Horatio Street in Greenwich Village and includes Piers 45, 46 and 51. Pier 45 features a large sunning lawn and shade structures, Pier 46 features a synthetic turf play field and Pier 51 features a playground with spray showers and a giant chips prow jutting over the edge of the pier deck. The upland park provides a unique linear experience of an esplanade constructed of distinctive granite and bluestone pavement. Beside the esplanade, sunning lawns are backdropped with lush plantings and sprinkled with display gardens, a granite fountain, dog run, two restrooms, food concessions and vertical architectural elements at primary entrance areas.

The park will encompass existing maritime uses and encourage new nautical activities such as water taxis and trans-Hudson ferries. Interpretive exhibits throughout the park will help educate visitors about the importance of various maritime activities.

One challenge for the project team involved design of a concrete pier deck that was constructed underneath the landscaped park. It had to be designed to accommodate the various loads of the landscaping, such as trees. The deck also had to be designed to include drainage so that water would not pool beneath the landscaping.

Installing 2-in. PVC drains with floating ball valves allowed rainwater to drain without water from the river infiltrating the deck.

Construction of the pier support piles presented another challenge. After conducting parametric studies to determine whether to use steel pipe or precast concrete piles, concrete piles were selected because of their long-term durability, which results in low maintenance costs.

Geotechnical borings showed there was rock 90 ft. below mean high water, requiring piles up to 135 ft. long, the longest precast concrete piles used in New York Harbor. The piles were designed to be lifted off barges at the site with a three-point pick and driven in a single piece without splicing.

The project team also designed a steel stinger with a hardened steel point that was cast into the pile during fabrication to ensure that the pile "bit" into the rock during driving.

The team had to take special measures due to the historic nature of the wharves, bulkheads and piers, which were constructed between 1874 and 1899 by the city's Department of Docks. At the time, the work was the first and largest of its kind.

The bulkheads vary, but generally consist of timber platforms supporting fill that is retained by granite block walls. The construction techniques were devised by the Department of Docks' first engineer-in-chief, Gen. George Brinton McClellan, a Civil War officer and engineer who was also a New Jersey governor.

In recognition of their historic significance, rehabilitation of the bulkhead wall required use, whenever possible, of granite salvaged from sections of the wall found to be in poor condition. Where repairs with salvaged granite were not possible, repairs were to be made with cast-in-place concrete.

The project team also had to meet fish habitat preservation requirements under the Endangered Species Act and the Magnuson-Stevens Fishery Management and Conservation Act. Under these provisions, deteriorated timber piles were removed by the cutting of the piles at the mudline or by pulling the piles out of the riverbed in a manner that would not result in substantial sediment resuspension.

To further minimize disruption, the number of piles added or removed was limited to 10 percent of the original number of piles.