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SWMU B-29

TO0019 Work Plan Addendum, December 2003

Site Description and History

SWMU B-29 is a former quarry area, approximately 3.5 acres in size, which was used for disposal of miscellaneous solid wastes, munitions, and construction debris.  In 1993, a decayed drum of nickel penetrate was observed at the site.  The drum was subsequently removed.  The eastern portion of the site was backfilled with soil at an unknown date.  Waste visible on the ground surface includes sand and shot piles, metal pipes, construction rubble, wood slats, and wood boxes.  Waste is also visible within an embankment along the east side of the site.  The boundaries for SWMU B-29 are shown in Figure B29-2.

Summary of Previous Investigation Results

Geophysical Survey

An EM geophysical survey was conducted in 1996 at SWMU B-29.  Three anomalies, which are potentially related to waste management activities, were found along the embankment at SWMU B-29.  Locations of these anomalies are shown in Figure B29-2.

Soil Borings

Six borings were advanced at SWMU B-29 in 2000.  Surface soils and subsurface bedrock samples were retained from the borings and analyzed for metals, VOCs, and SVOCs.  It is noted that bis(2-ethylhexyl)phthalate was detected in many of the samples collected at SWMU B-29. However, because it was also detected in the equipment blank, further analysis for this compound is not warranted.

Boring SB01 was advanced adjacent to the embankment, in one of the three geophysical anomalies.  The concentrations of several metals and SVOCs (benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, chrysene, fluoranthene, and pyrene) exceeded RRS1 closure standards in the soil sample, whereas, at depth, only lead and nickel slightly exceeded bedrock RRS1 standards in one sample each.  The SB01 soil sample was the only sample that had reported SVOCs in excess of RRS1 standards.

SB02 was advanced just west of a rubble pile in the central portion of the site. The concentrations of copper and lead in the surface sample, and copper and zinc in a bedrock sample, were greater than RRS1 closure concentrations.

Lead and copper were measured above RRS1 standards in the soil from SB03, located near a pile of sand and shot in the eastern portion of the site.  Zinc was measured slightly above RRS1 closure concentrations in the shallow bedrock sample.

The fourth boring, located near the embankment and situated within one of the three geophysical anomalies, had metals concentration in the bedrock samples only that were above RRS1 closure concentrations.  These exceedances included arsenic, chromium, lead, nickel, and zinc, respectively.

The backfilled area in the eastern portion of the site, near the embankment and within the boundaries of the third geophysical anomaly, was investigated with SB05.  None of the potential COCs were observed to be above RRS1 closure standards in SB05; however waste (metal fragments, asphalt) was encountered in the boring.

SB06 was also advanced near a pile of sand and shot, but in the northern portion of the site.  Lead was noted above RRS1 standards in the soil sample retained from the surface.

Closure Plan and Sampling Recommendations

Closure of SWMU B-29 under RRS1 requires removal of waste visible on the ground surface and in the embankment at the site and delineation and subsequent remediation or removal of contaminated soil at the site.  The waste, including sand and shot piles, metal pipes, wood slats and boxes, and construction rubble, must be removed from CSSA for off-post disposal to pursue RRS1 closure with respect to the soil unit at SWMU B-29.  Contaminated soil identified at B29-SB01, SB02, SB03, SB05, and SB06 must also be removed.  Groundwater and competent bedrock will be addressed as part of the groundwater operable unit.  The soil excavation will extend to the depth that waste or waste residue is encountered or to bedrock, whichever comes first.

Excavated material will be characterized with TPH and TCLP metals (Texas Eleven) analyses prior to disposal.  The estimated volume of waste material and waste residue present at SWMU B-29 is approximately 2,000 CY.  Based on waste at most other SWMUs at CSSA, it is likely that this waste, with the exception of the sand and shot piles, is non-hazardous.  The sand and shot piles will be containerized separately, and sampled separately for waste characterization.  This material may require PIMS stabilization prior to disposal.

Confirmation samples should be collected following removal/remediation to verify that no contamination remains.  Analysis should include arsenic (SW–7060A); chromium, copper, nickel, and zinc (SW-6010B), lead (SW-7421), and SVOCs (SW‑8270C), based on results of the historic sample analyses.  Samples will be collected at a frequency of one per 100 linear ft of sidewall, with a minimum of one sample per sidewall.  If the bottom of the excavation is bedrock, bottom samples will be collected at a frequency of one per 20,000 ft2 of bottom surface area, with a minimum of two samples per excavation area.  If the bottom of the excavation is soil, bottom samples will be collected at a frequency of one per 100 ft (100-ft grids).

Summary Of Planned Work

  1. Excavate waste and waste residue in embankment and other areas of the site, with the exception of the shot piles.  If practical, separate metal debris for recycling.  Contaminated soils in the vicinity of B29-SB01, SB02-SB03, SB05, and SB06 must also be excavated.

  2. Excavate and immediately containerize shot piles and surrounding soil.

  3. Collect samples of excavated soils for waste characterization purposes.  One composite sample consisting of five aliquots will be collected per 1,000 CY of soil.  Analyze samples for TPH and TCLP antimony, arsenic, barium, beryllium, cadmium, chromium, lead, mercury, nickel, selenium, and silver.

  4. Collect samples of the excavation sidewalls and bottom.  Samples will be analyzed for SVOCs, arsenic, chromium, copper, lead, nickel, and zinc; these parameters exceeded RRS1 criteria in the samples collected at the site in 2000. 

  5. Continue excavation until RRS1 soil criteria or competent bedrock, whichever comes first, is reached.

  6. Re-grade the site with clean fill and reseed.

  7. Validate data and prepare Closure Report for SWMU B-29.