Buried Pipe Wrap and 3 Percent Chrysotile Soil at a Former Auto Shop
During excavation for a new medical office building in Aurora, a contractor uncovers buried pipe wrap fragments and discolored soil at 4 to 6 feet below grade, on the footprint of a former auto repair shop. The environmental consultant collects four soil samples; three report 2 to 4 percent chrysotile by weight, and one reports 0.5 percent. About 250 cubic yards of soil have been stockpiled uncovered at the back of the site, and the contractor plans to haul it to a nearby construction and demolition (C&D) landfill tomorrow. The owner wants to know whether the soil is regulated asbestos waste, whether the C&D landfill can take it, and what has to be done before the trucks arrive.
1. Is the excavated soil regulated, and how should the sampling results be interpreted?
Read the worked answer
The soil is regulated asbestos-contaminated soil. Three of four samples contain 2 to 4 percent chrysotile by weight, well above the 1 percent threshold generally used to identify asbestos-containing material, and the soil also contains visible pipe wrap fragments. The single 0.5 percent result does not make the stockpile clean; it shows that the material is heterogeneous, which is typical of fill and demolition debris. The conservative and correct interpretation is that the entire 250 cubic yards must be managed as asbestos-contaminated unless further systematic sampling of the stockpile demonstrates otherwise. The consultant should document the sampling pattern, depth, and lab methods. The stockpile must be wetted and covered immediately to prevent visible emissions and dust migration, and runoff must be controlled. The owner should also notify CDPHE under the soil provisions of Regulation No. 8, Part B. Waiting until the trucks arrive to decide is not acceptable.
2. Can the material go to the nearby C&D landfill, and what handling and disposal requirements apply?
Read the worked answer
No, not without confirming that the landfill is permitted to accept asbestos waste. Most C&D landfills are not authorized for asbestos disposal. The soil and pipe wrap must go to a landfill approved to accept asbestos-containing waste, with prior approval from the landfill operator. The loads must be wetted and covered during transport, and the material must be in leak-tight containers or otherwise handled so that no visible emissions escape. The generator must keep shipment records identifying the origin, quantity, and destination, and the landfill must cover the material with at least six inches of compacted non-asbestos waste by the end of the operating day, or use an approved alternative. The contractor should not blend the high-concentration soil with the 0.5 percent sample or with clean fill to get below 1 percent; dilution is not a treatment method and does not change the character of the waste. If any material is to remain on site, that requires a CDPHE-approved plan, not an informal decision in the field.
3. What worker-protection and site-control measures should be in place while the stockpile is being loaded?
Read the worked answer
The work is both a solid-waste issue and an occupational exposure issue. Workers loading the stockpile should use wet methods, avoid dropping or dumping material from height, and wear appropriate respiratory protection and protective clothing under OSHA's asbestos standard. A decontamination area, hygiene facilities, and proper training are needed, and air monitoring should be conducted to verify that dust controls are working at the perimeter. The stockpile should remain covered when not being loaded, and vehicle tires should be cleaned or washed before leaving the site to prevent tracking contaminated soil onto public roads. The contractor should also consider that the 0.5 percent sample does not allow treating part of the pile as clean; segregation would require a defensible sampling plan and CDPHE concurrence. The judgment call is to treat the entire stockpile as contaminated until the regulator agrees otherwise, rather than to manage to the lowest sample result.