by Luke Hall, professional geologist
Clean dirt. To a person with a three-year-old son, the term sounds like a cruel joke. In reality, it is an issue that can cause serious problems for developments.
Picture this scenario: you have purchased a residential property with the intention of redevelopment. For whatever reason, perhaps raising the grade of the surrounding area to prevent flooding or removal and backfill of previous foundations and structures, you hire a contractor to bring in soil from off-site. You have done your due diligence and you are comfortable in the knowledge that the property you purchased does not have a history of environmental issues. But your contractor is trying to up their profit margin so they, unbeknownst to you, have decided to bring in soil from a former industrial area that is $20 cheaper per ton. This soil just so happens to be contaminated with extremely high levels of pesticides. Now your property, which previously had no environmental issues, is a potential health risk to the future residents at the property and you are the responsible party.
This scenario is unlikely because most contractors understand that they are just as liable as the property owner and the owners of the original property that produced the contaminated soil. Additionally, most contractors have a source for soil that they either own or have historically used that is generally accepted as clean. Yet, as unlikely as this scenario is, it isn’t unheard of and the existence of state and federal environmental regulations concerning what is and what is not clean soil proves it.
The Tennessee Department of Environment and Conservation recently began recognizing the New Jersey Department of Environmental Protection regulations on the certification of clean soil. Based on the New Jersey regulations, a sampling protocol must be established to prove that a source for soil used as backfill is not creating additional environmental issues. These regulations stipulate a sampling protocol that is controlled by the amount of soil you plan to import to a property. For a property where 2,500 tons of soil is needed, 16 samples are required to prove the soil is clean. The soil must be sampled for volatiles, semi-volatiles, RCRA metals, PCBs, pesticides, herbicides and total petroleum hydrocarbons. For the 16 samples of the previously listed constituents, you are looking at roughly the cost of a very nice used Toyota Corolla in laboratory fees.
Luckily, the regulations also stipulate that the sampling frequency can be reduced if an environmental assessment has been performed at the site. An environmental assessment for a source of clean soil can be as simple as an extensive record review to prove that the source and its surrounding areas have never been used for any purpose with the potential to contaminate the soil. If the source can be proven to be at little to no risk of past contamination, then sampling frequency can be reduced dramatically and with minimal cost. While proving that the soil you are using is clean can be a hassle and alter your construction schedules, it is the prudent thing to do. It is the only way to be 100 percent sure that the soil you are using for your project will not cause environmental issues where none previously existed.