Underground Corrosion after 32 Years: A Study of Fate and Transport

In 1970, the National Bureau of Standards (NBS) initiated a comprehensive long-term corrosion test. The NBS, now known as the National Institute of Standards and Technology (NIST), buried over 1000 specimens-consisting of different stainless steel types, specialty alloys, composite configurations, and multiple material forms and treatment conditions-at six distinctive soil-type sites throughout the United States. Researchers from Department of Energy (DOE) National Laboratories at the Idaho Engineering and Environmental Laboratory and Savannah River recovered and analyzed one set of specimens after 34 years of burial. Objectives were to enhance understanding of subsurface corrosion and near-field contaminant transport. The specimens were buried at a US Coast Guard base near Wildwood, NJ. They were originally buried in dry, sand (poorly-graded sand with an average saturated hydraulic conductivity of 4.7 X 10-3 cm/sec) but upon recovery, were found to rest about 2 feet below the water table. In 1970, the sand was vegetated with beach grasses, now it supports abundant vines, shrubs, and small-to-medium diameter trees. Background soil and water samples were collected for chemical and microbial analysis. Soil pH ranged from 5.71 to 6.64, while water pH ranged between 4.23 and 5.55. Soluble chloride ranged between 16 and 59 mg/L. Additional samples were collected to determine whether corrosion product transport had occurred in the soil or water and how far. Sensitized Type 301 and Type 304 stainless steel plates and U-bend specimens sustained the greatest observable corrosion with adhering corrosion product. This abstract addresses the initial investigations.