ASARCO Corrective Action and Compliance
Status of Asarco’s Compliance with 2005 Corrective Action Directive
ASARCO identified that Category I material should be consolidated into repository cells and asphalt pavement should be applied over Category II material. Category I materials are residual by-products typically associated with specific current and past facility operations. Category I materials include remediation waste and material that could impact human health and the environment. Category II materials are large volumes of residual by-products with lower COC concentrations than Category I materials. However, Category II materials could become a potential contaminant source if they are not properly managed.
ASARCO excavated 197,000 cubic yards of Category I material from nine identified source areas. The material was consolidated and placed in three on-site repository cells. Figures 3 & 4 show typical cross sections of a repository cell drawing. The repository cell floor is comprised of a layer of a geosynthetic clay liner (GCL), High Density Polyethylene (HDPE) geomembrane and a geocomposite drainage layer. The combination of the GCL and HDPE liner will create a nearly impermeable barrier surrounding the buried material. The GCL and HDPE liners prevent the material and liquid generated from the waste (if any) from leaching out of the cell. The HDPE liner has chemical and physical characteristics that are not adversely affected by the placement of waste.
After the waste material is placed into the repository cell, a cell cover is constructed. The proposed cover is comprised of asphalt, with soil, GCL, flexible polyethylene material, and a geocomposite drainage layer underneath the asphalt. The GCL and a flexible polyethylene material will create a nearly impermeable barrier to prevent surface water from coming in contact with the buried material. A geocomposite drainage layer is then placed on top of the polyethylene layer to ensure that any water seeping through the asphalt will drain away from the repository cell. This procedure is commonly used in landfill construction. At this time, cell covers have been installed on cells 1 and 2. ASARCO applied an emulsion cover layer on repository cell 3 in 2009 as an interim measure for erosion and dust control.
ASARCO paved a total of 22 acres of Category II material with asphalt to minimize surface water infiltration and provide dust suppression.
ASARCO has conducted a pilot study to determine an appropriate remedy for preventing contaminated groundwater from impacting the Rio Grande.
Reports and Data
- Construction Report Part 1 and Part 2 and Addendum 1 to the Construction Report
- Groundwater and surface water data
TCEQs Proposed Plan for Closure of the Site
Completion of the unfinished tasks specified in the TCEQ Corrective Action Directive (dated May 20, 2005) include the installation of groundwater remediation treatment systems to provide hydraulic control to prevent the migration of contaminated groundwater to the Rio Grande, long-term operation and maintenance of the systems, covering 16 acres of Category II material with asphalt pavement, and construction of the fourth repository cell for Category I material. Additional tasks are necessary since the facility will no longer be operating. These tasks include the demolition of many structures, covering an additional 60 acres of slag with asphalt pavement, installation of a fence to enclose the facility, and placement of the slag fine and dust (minus 50) piles into a repository cell.
The TCEQ estimates that it will cost $52,005,186 to address contamination at the site and reach closure.