SAN CARLOS STREET ORDOT
The Ordot Landfill is located near the Village of Ordot and Chalan Pago on the Island of Guam. The Ordot Landfill was established in a ravine which slopes steeply to the Lonfit River. The site has been a dumping ground since the 1940s, serving as Guam’s primary landfill for industrial and municipal waste. The site is currently operated by the Government of Guam through the Guam Dept. of Public Works. Current operations at the facility use almost the entire waste disposal area, with only approximately four to seven acres of the oldest portion of the landfill not in use. The 1988 ROD stated that the area covered by the landfill is 47-acres, however using both the topographic map and aerial photograph from 1994, the total acreage is calculated to be approximately 23 acres. One inactive area forms the steeply sloping toe of the landfill. The depth of disposed waste at the time of the ROD was approximately 100 feet. During more recent site visits, it was observed that there were 16 lifts of waste at the site, each measuring approximately 8-10 feet in depth. The toe of the landfill is approximately 1,000 feet from the Lonfit River and leachate streams emanate from points along the contact of the landfill toe and the clay soils comprising the banks of the Lonfit River. The site is located in a basin between two ridges in a volcanic upland region near the center of Guam at an elevation of 200 feet above mean sea level. Surface water consolidates near the northeastern boundary of the site and flows into and beneath the landfill. Runoff primarily exits south of the site into the Lonfit River, which merges with the Sigua River to form Pago River, which then drains into Pago Bay. The site is underlain with a few feet of very fine-grained volcanic sediments with a high clay content. Typically, these deposits range in color from gray to light orange in fresh exposures and gray-green to dark red in weathered exposures. The parent bedrock underlying these surficial deposits comprise tuffaceous shales and sandstones. These rock formations can range in thickness from several feet to tens of feet thick, particularly in the tuffaceous shales. Weathering is prominent to depths ranging from 10 to over 30 feet below ground surface. Both weathered and unweathered rocks appear to have extremely low permeability due to their fine-grained matrix. A major northwest-southeast trending fault is located north of the site. This fault is believed to divide the northern limestone plateau from the southern volcanic province where the site is located. Drinking water from the volcanic region is obtained from surface water upgradient of the site and groundwater from the northern limestone aquifer (the Northern Guam Water lens). Groundwater in the limestone aquifer north of the site is encountered between 120 and 330 feet bgs. No interconnection between the aquifer located in the volcanic formation beneath the site and the Northern Guam Water lens has been documented. The Governor of Guam designated Ordot Landfill as Guam’s highest priority site for Superfund cleanup. It was placed on the National Priorities List for action under Superfund on September 8, 1983.
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