Conditions

Billions of liters of liquid waste, some containing radionuclides and hazardous chemicals, have been released to the ground on the Hanford Site since the 1940s. Some of these contaminants were trapped above the water table and some reached groundwater. The Groundwater Performance Assessment Project monitors groundwater on the Hanford Site for DOE to track the spread of these contaminants. Groundwater is being remediated at sites that have been identified as requiring immediate action. The results of monitoring for each fiscal year are summarized in the annual groundwater monitoring report.

Because contaminants were disposed to the ground or were contained in leaking tanks, groundwater is a major pathway through which contaminants move across the Hanford Site. The most widespread contaminants are tritium, iodine-129, and nitrate.

Groundwater Flow

Researchers take hundreds of measurements of water-level elevations each year beneath the Hanford Site. Water-level data and water-level maps are used to support the calibration of groundwater flow models and to interpret groundwater sampling results.

Groundwater in the unconfined aquifer flows from regions where the water-table elevation is high (recharge areas) west of the Hanford Site to regions where it is low (discharge area) near the Columbia River. Steep gradients occur in the west, east, and north regions of the Hanford Site, while shallow gradients occur within and west of the 100-B/C Area , southeast of the 100-F Area, and in the central portion of the Hanford Site. This is largely due to differences in hydraulic conductivity and aquifer thickness. Information about groundwater flow and water-table elevations are contained in the annual groundwater monitoring report.

Groundwater Contamination

The major sources of groundwater contamination on the Hanford Site are former liquid waste facilities in the 100, 200, and 300 Areas. The vast majority of radioactive waste at the Hanford Site was created during the production of nuclear materials. Tritium, nitrate, and iodine-129 are the most widespread contaminants in groundwater on the Hanford Site. DOE has developed a plan to accelerate cleanup of Hanford's groundwater, which will return it to its beneficial use where practicable or will at least prevent further degradation. Under the accelerated plan DOE will (a) remediate high-risk waste sites, (b) shrink the contaminated area, (c) reduce recharge, (d) remediate groundwater, and (e) monitor groundwater.

Detailed information about the current status of groundwater contamination is contained in the annual groundwater monitoring report.