ANDREWS (CBSDFW.COM/AP) — The Dallas-based company operating a low-level radioactive waste dump has disposed of the first material at the West Texas site on the New Mexico state line.

Waste Control Specialists spokesman Chuck McDonald said Friday a small amount of medical waste from Texas was placed inside the disposal pit earlier in the day.

McDonald says the waste is inside a 55-gallon metal drum that was placed in a 10-foot-tall concrete cylinder. The disposal pit is 600 feet deep, with 7-foot-thick steel and concrete flooring and walls.

On Wednesday, state regulators gave approval to begin disposing of waste.

Environmental groups are concerned over geology at the site and the potential to contaminate underground water sources they say are too close.

The company is a subsidiary of Valhi, a huge conglomerate owned by Dallas billionaire Harold Simmons.

The site is near Andrews, about 320 miles west of Fort Worth and 35 miles north of Odessa.

Copyright 2012 CBS Local.  The Associated Press contributed to this report.