Test Pile Program at Naval Base Kitsap

Test Pile Program at Naval Base Kitsap - Bangor

Colson, Nick / Lindquist, Doug / Stockwell, Joseph

This paper presents the case history of a test pile program at Naval Base Kitsap - Bangor. The information gathered in the study included: compression and tension data from pile-soil interaction; acoustic monitoring data during pile driving and effectiveness of noise mitigation measures; evaluation of marine mammal and bird monitoring methodology; and, evaluation of marine pile-driving equipment capabilities. Carried out in water up to 100 feet (30.5m) deep and in an environment of frequent wind and waves, the program was intended to: (1) verify the ability to install large diameter steel pipe piles using a vibratory hammer to the desired tip elevations with glacially consolidated soil; (2) gather compression and tension capacities within the soil-bearing layers; and (3) help define the environmental requirements for pile-driving work performed at the site. Over a three-month period, the program installed 29 opened-ended steel pipe piles that ranged from 117-197 feet (35.7-60.0 m) in length and 2-4 feet (0.6-1.2 m) in diameter. Bearing capacities were recorded for each pile, and two full-scale tension load tests were conducted in general accordance with ASTM D3689 (ASTM 2007). Subsurface conditions at the test pile site consisted of a thin layer of sediment and beach deposits over very dense granular soils. The piles were installed using a variety of pile tip conditions (driving shoes, end hardening, and unaltered) in an attempt to determine benefits or drawbacks of each during installation. Pile Driving Analyzer (PDA) and the Case Pile Wave Analysis Program (CAPWAP) were performed on 23 of the 29 piles to measure their capacity. The paper also discusses the constraints placed on the program by the significant permitting requirements that protect marine wildlife and habitat at the site, and how requirements were accommodated in the program. Environmental regulations mandated marine mammal and wildlife monitoring and a reduced number of impact hammer blows per day and cumulatively during the project.