Dear PoPville – What Happens to the Dirt Excavated from Huge Construction Sites?

Dear PoPville,

Where does all of the excavated dirt from these gigantic parking lots underneath the new downtown DC buidlings go (ie City Center, Mariott Marquis, O St. Market, etc.)? – Even the smaller sites have what is otherwise a significant amount of excavated dirt. Is it contaminated? Is it recycled for other projects, of perhaps just dumped in a landfill.

12 Comment

  • I was just wondering the same thing this weekend about all the debris from the WalMart site on Georgia.

  • It is used (most often sold) as fill dirt for other construction projects.

  • Before ground is broken the site has to go through Phase I/Phase II site assessment during which environmental concerns are addressed. If it is found to be contaminated the extent of the contamination is mapped and an environmental consultant is typically on hand during the excavation to screen the excavated soils. Contaminated soil is taken to a facility which typically incinerates the contaminated material. Any uncontaminated material can be used as fill later on in the project or disposed of at a facility for reuse elsewhere.

    • Or just disposed of in a landfill, I guess. I worked on the environmental side of things for a few years, didn’t really concern myself with the uncontaminated material.

      • Even if uncontaminated, different soil types have different uses. If the soil has low organic content and is determined to be compactable, it would most likely be hauled off to another project and used as structural fill. In cases where the organic content is higher, it is often used in green spaces such as surface mine reclamation (many sand a gravel mines close by are turned into parks this way) or for fill in non-structural areas of other new projects. As you stated, contaminated soils are very closely monitored and must be properly disposed of.

  • I think the bottom line is that dirt is a lot more valuable than you might think so the chances of someone just ‘throwing it away’ are pretty low. Which I think is a good thing.

  • If the dirt is uncontaminated, suitable for fill and there is demand it is hauled and dumped at that site. Otherwise there are dirt dumps in PG county, Frederick County, etc. where a ravine or other low spot is just being filled up. Much of the dirt excavated in DC is wet and completely unsuitably for reuse and goes to the dump. If it’s contaminated it’s hauled to various sites (Richmond, Ohio, etc.) where it’s “cleaned” usually with petroleum contaminants this is by burning the dirt until the petroleum is burned off then it’s mixed with clean dirt and dumped in a landfill. If it’s not wet and not contaminated, then ideally demand is found. Dirt is bought and sold among the excavators in town frequently if they don’t have their own project to take it to. This is usually beneficial because the round trip time for each load is cut down significantly if it can be hauled to a construction site in town instead of to the dump in PG County, Frederick County etc. which means more dirt can be excavated per day.

  • Or, they can always dig another hole and put the dirt in the new hole.

  • One place it goes is down a narrow, quiet street in Shaw marked “No Thru Trucks Over 1¼ Tons Capacity.”

    Anyone know how to get better signage or enforcement from DDOT or the MPD?

  • It ends up in the Chesapeake Bay

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