The elevated concentrations of chrysotile asbestos found at the repository indicate that the potential for inhalation exposures exists.  Because of the lack of vegetation and other surface water drainage issues associated with the dry retention basin, wind and surface water and mechanical erosion could eventually expose and damage the protective polyvinyl chloride (PVC) liner, which could expose the underlying asbestos-contaminated material and soil.  At the parking area, sections of the asphalt are settling and allowing surface water and sediment to accumulate.  The conditions of both areas of the repository increase the potential for the asbestos-contaminated soil to be released.

Exposure to airborne friable asbestos may result in potential health risks because persons breathing the air may breathe in asbestos fibers. Continued exposure can increase the amount of fibers that remain in the lungs. Fibers embedded in lung tissue over time may cause serious lung diseases, including asbestosis, lung cancer, or mesothelioma.

Refer to Polreps #1,  #2 and #3 for initial site inspection results that led to the removal actions before 2014.

Following the notification of these issues by the FBC to EPA, EPA's Superfund Technical Assessment and Response Team (START) contractor investigated the site in March 2014 and collected samples of the dry retention basin topsoil for soils testing. In August 2014, EPA returned to the site with its Emergency and Rapid Response Services (ERRS) and START contractors and met with representatives of the FBC to further assess these issues. Based on these March and August 2014 site inspections, EPA identified the following problems:
 

·        The settled areas of the asphalt allowed water and sediment to puddle near the engineered retaining wall;

·        Surface water did not drain properly from the asphalt parking lot through the dry retention basin and into the dry well;

·        Following hydroseeding in October 2012, a grass cover had never been established, and the dry retention basin was only sparsely vegetated;

·        The steep slopes at the northeastern of the retaining wall did not provide convenient access to the lower sections of the wall for maintenance and repair activities.

       .      The steep slopes along the asphalt at the southwest of the retaining wall were not graded,
             and represented a liability issue since people or vehicles could drive off the edge or get hurt. In addition, soil was eroding along the steep edge and out from under the asphalt, and, if not addressed could expose asbestos-contaminated soil.

ERRS and START contractors and EPA OSC mobilized to the site on Monday April 20, 2015.  START drove the EPA Region 10 communications rig to be used as the site's command post.  Equipment was also delivered on Monday to the site and set to promptly start the planned repairs (described below) on the repository on Tuesday morning.   

·        Repair the settled areas of the asphalt to allow for proper surface water drainage and to prevent surface water from ponding on the asphalt near the engineered retaining wall;

·        Establish vegetation in the dry retention basin by adding additional top soil and adding a new seed mix optimized for local climate conditions;

·        Reconstruct the surface details of the corrugated metal pipe around the dry well to allow for better drainage of surface water in the dry retention basin;

·        Add a gravel apron at the eastern edge of the dry retention basin to allow for better drainage of surface water from the asphalt parking area;

·        Construct ramps at the northeastern and southwestern edges of the retaining wall to allow for better access to the lower sections of the wall for inspections and maintenance.

See POLREP #6 for activities conducted April 20 through April 23, 2015.  This POLREP covers the operational period from April 24,2015 through April 28, 2015.

1.      Excavation of the asphalt repair was completed (depth of 3 feet bgs), and the final two trucks/pups were loaded with the waste material (asphalt and contaminated soil) from the eastern extent of the excavation, and excavated material was transported to the landfill.

2.      ERRS performed sweeping of the parking lot after the final haul truck removed the last of the contaminated soil.

3.      ERRS subcontractor arrived on site to perform in-situ compaction testing of the first lift in the western half of the asphalt repair area. Initial tests indicated low compaction and ideal moisture content. ERRS applied water and recompacted the first lift to maximum achievable compaction (95% to 98%), prior to placement of the second lift. ERRS performed blending of the subbase material stockpiles to evenly distribute fines and gravel particles throughout the stockpile.  ERRS completed two lifts by the end of the day, and compacted all day long.

4.      Final delivery trucks import the last gravel fill material, for a total of 13 loads.

5.      ERRS continued to excavate for the gravel apron trench.

6.      START performed dust monitoring with the DataRAMs, and the results were all less than the site action limit. START collected three air samples from the work zone, including two perimeter and one personal, which will be submitted to an off-site laboratory for PCM testing. 

Saturday, April 25

1.      ERRS completed two lifts over the course of the day, compacting each lift for a minimum of 4 hours.

2.      ERRS used sweeper to clean parking lot.

3.      START performed dust monitoring with the DataRAMs, and the results were all less than the site action limit. No  air sampling was conducted as no all contaminated material was either removed from the site or under an aggregate cap and contained, and no further air samples are to be collected.

4.      ERRS used sweeper equipment to clean the parking lot.

5.      ERRS continued to work on gravel apron. Geotextile placed along the base at the bottom of the washed rock apron. Washed drain rock was placed in the trench and along the length of the interface of the asphalt and dry retention basin.

6.      Evidence of cars hitting the top of the retaining wall was observed, and parking space stoppers will be installed. 

Monday, April 27

1.      ERRS subcontractor arrived on site to perform in-situ compaction testing of the two lifts placed on April 25. Test results indicated that compaction rate was achieved (98%), with only a few areas not at design compaction. ERRS applied water and recompacted to achieve design compaction levels or higher. ERRS completed the final two lifts by the end of the day, and compacted all day long.  The compaction contractor tested the final lift and confirmed that final design compaction was achieved throughout the repair (98% to 100% compaction).

2.      START performed dust monitoring with the DataRAMs, and the results were all less than the site action limit. No air sampling was conducted.

3.      ERRS used sweeper equipment to clean the parking lot.

4.      ERRS continued to work on the gravel apron.

5.      Construction started on the lower access ramp. One small (<6-inch diameter) tree was removed that was in the path of the ramp.

Tuesday, April 28

1.      ERRS surveyed the asphalt repair area and added aggregate to bring to final grade and prepare for asphalt.

2.      START performed dust monitoring with the DataRAMs, and the results were all less than the site action limit. No air sampling was conducted.

3.      ERRS continued to work on the lower access ramp.
4. Nez Perce Groundwater Project Manager conducted a site visit with EPA.