Environmental assessment section on physical resources, 2001

NYC 9/11 Public Portal Document

During WTC repair or restoration activities, the construction contractor would need to make provisions for excavation shoring or stabilization necessary to prevent collapse or slumping of excavation walls during construction. To avoid potential impacts to unique geological resources, relevant NYC plans would need to be consulted. Potential risks associated with geohazards can normally be reduced to acceptable levels via proper design developed by the > ssponsible party or applicant. Appropriate geotechnical studies and engineering design would be used by the responsible party to design earthquake resistant facilities to mitigate liquefaction and other seismic hazards to acceptable levels, especially in the Battery Park City area.

The construction, repair or renovation of the damaged subway system would result in extensive excavation activities. The soil characteristics and local geology would influence the tunnel construction methods and excavation stabilization methods. These effects would be considered during project planning and any limitations would be overcome during the design phase. Soil borings and geotechnical testing for parameters of Soil strength and cohesion measurements would be collected and this information will be incorporated into subway design. Earthquake frequency and strength data would be incorporated into subway design in accordance with building codes. No significant impact to soils or geology would be expected as a result of repair, construction or operation of the damaged subway system.

3.1.2 CLIMATE AND AIR QUALITY

The climate of New York City is defined as coastal maritime with hot summers and cold stormy winters. The annual mean temperature is 54.6 degrees Fahrenheit (°F). The lowest recorded daily minimum temperature was -3° F and this occurred in January 1994. The highest recorded daily maximum temperature, 107° F, which ocQurred in July 1966. Weather conditions are variable in the fall and winter with a series of ^torms producing strong winds; weather conditions are more stable in the summer. The lowest monthly average temperature, 32.3° F, occurs in January. The highest monthly ave.age temperature is 75.4° F and this temperature occurs in July and August. The annual average precipitation is 42.7 inches, and the annual average snowfall is 25.4 inches. As shown below, prevailing winds in the fall and winter months tend to be out of the northwest, although strong northeasterly winds are not uncommon. Northeasterly storms last two to three days and may produce severe conditions with high winds, cold rain or snow with flooding possible along the coast. Prevailing winds in the summer are southerly and occur 9 percent of the time (Figure 3-3). In November and December, wind dispersion mechanisms are at the lowest level and atmospheric conditions are stagnant. The area experiences considerab’f -ainfall throughout the year with a slight decrease in total precipitation during the winter months of the year. Mean monthly precipitation ranges from 3 to 4.5 inches.

3-6

NYC-WTC_000141700