Basin F

Basin F was constructed by the United States Army in 1956 at the Rocky Mountain Arsenal, to provide for the disposal of contaminated liquid wastes from the chemical manufacturing operations of the Army and its lessee Shell Chemical Company.

As originally constructed, Basin F was equipped with a catalytically-blown asphalt liner (approximately 3/8-inch thick) covered with a convert|12|in|mm|sing=on protective soil blanket. Basin F had a maximum capacity of 243 million gallons and covered approximately 93 acres. Throughout the operation of Basin F, the saline concentration increased as water evaporated. The liquid formerly stored in Basin F is very salty water that contains some metals, hydrazine, wastewater, and toxic organics, which are only about 1 percent of the liquid.

Interim response

The Basin F Interim Response Action began in March 1988 and involved the transfer by tank truck of 4 million gallons of Basin F liquid to three 1.3-million-gallon holding tanks and approximately 6.5 million gallons to a double-lined holding pond.

The Interim Response Action at Basin F was not without some major obstacles that caused delays and challenged the Army's engineers. In May 1988, near the start of the project, a heavy rainfall classified as a 25-year/24-hour event occurred which increased the volume of Basin F liquid. In June 1988, a tornado touched down near the tanks and ponds. The need to inspect and repair structures and equipment affected by the twister caused a minor schedule delay.

The increased volume of liquid in Basin F caused by the heavy rainfall in May 1988 required additional storage capacity. Two double-lined holding ponds were constructed: a 5.5-million-gallon pond (Pond B) and an 6.5-million-gallon pond (Pond A). The convert|488000|cuyd|m3 of basin overburden, liner, and subsoils were excavated and placed in a waste pile located within the basin area.

Remediation of Basin F

The basin floor was capped with convert|12|in|mm of compact clay and convert|6|in|mm of topsoil and revegetated with native grass. This portion of the Basin F Interim Response Action was completed in August 1989.

Once the liquid was drained from Basin F, the drying of the soils, sediments, and liner began. This project caused an odor resulting in discomfort to members of the surrounding community. Because of the Army's concern for the comfort of the local community during the soil drying, air purifiers were distributed to affected homes in the community to help alleviate the odors. When the odor problem began, the Army asked several health agencies to study the problem to determine if there were any long-term or acute health affects. Toxicologists from Colorado State Health Department, United States Agency for Toxic Substance and Disease Registry, United States Environmental Protection Agency, Shell Oil Company, Tri-County Health, the Army's Surgeon General's Office, and Foster-Wheeler (formerly Ebasco, the contractor for the project) identified the compounds and determined that there were no acute health effects. The odors ended with the completion of the excavation in December 1988.

The total cost of the project was about $45 million. The decision on the final disposal of the liquid was reached in March 1990.

ee also

*Rocky Mountain Arsenal

External links

* [http://www.pmrma.army.mil/cleanup/facts/basin-f.html Basin F Interim Response Action]
* [http://www.pmrma.army.mil/involve/basinFframe.html Basin F Waste Pile]