Brownfield redevelopment projects are typically on tight schedules, and one delay can have a domino effect that ultimately costs the site owner and developer millions of dollars. That’s why it’s critical to choose remediation technologies and approaches that quickly and reliably achieve site goals. In situ thermal remediation (ISTR) can be an ideal approach for achieving all the soil and groundwater goals required for redevelopment, on time and on budget.
In this blog post, I’ll outline which thermal technologies are suited for brownfield sites, and explain the reasons why this approach should be your top choice for upcoming redevelopment projects.
What Thermal Technologies Can Be Used for Brownfield Sites?
Because every brownfield site is different, there is no standard thermal heating technology that would be the best choice for redevelopment. Any of the three primary ISTR technologies can be used alone or sometimes in combinations. These technologies are:
- Thermal Conductive Heating (TCH), which relies on heat moving out to efficiently and uniformly radially around heaters by thermal conduction (i.e., transfer of energy from the heater directly to the soil) to heat the subsurface.
- Steam Enhanced Extraction (SEE), which delivers steam to the subsurface through small diameter, easy-to-install, short screen intervals (one to three ft.) to allow maximum horizontal spreading of the steam and thorough heating of the targeted intervals.
- Electrical Resistance Heating (ERH), which safelyapplies a standard 3-phase AC current to custom-engineered finite-length electrodes using state-of-the-art power delivery and control systems (PDS).
These technologies can treat a wide range of contaminants and subsurface conditions, such as:
- VOCs, CVOCs, BTEX, SVOCs, PAHs, PCBs, pesticides, PFAS, TPH, creosote/coal tar, DNAPL, LNAPL
- Clays to sands and gravels
- Fracture bedrock
- Above and below the water table
- Low and high groundwater flux zones
- Below buildings and in and around sensitive utilities (natural gas, electrical, fiber optics, water, and sewer)
It is typical to achieve >99.99% reductions when using thermal remediation, and low soil cleanup goals are possible (e.g., 5 µg/kg), too. The technologies can also be combined (e.g., ERH and SEE) to achieve soil goals at more challenging sites with highly variable geologies and groundwater flow conditions.
What Are the Benefits of Using Thermal Remediation for a Brownfield Project?
ISTR is routinely used for aggressive and safe remediation of high mass/DNAPL source zones, and has a track record of success at brownfield sites across the globe. There are eight major benefits of using thermal technology that make it especially suited for redevelopment projects.
- Quick results: Depending on the contaminants, site conditions and remedial goals, remediation times for thermal projects typically range from six to eight months. When you factor in the design phase, permitting, construction, operation/remediation, and demobilization, the project spans about 10 to 12 months. That is a dramatically shorter timeframe than any other remediation technology capable of providing similar results.
- Proven technology: ISTR has been successfully and safely implemented at more than 600 sites worldwide. Numerous papers have documented its efficacy in treating difficult high mass/DNAPL source zones in complex geologic settings. The EPA, USACE and commercial enterprises rely on thermal remediation as the go-to approach for difficult sites with recalcitrant contaminants.
- Reliable outcomes: ISTR is proven to reliably achieve low to very low soil and groundwater cleanup goals at numerous sites for a wide range of contaminants. Typical goals that have been achieved include maximum contaminant levels (MCLs) for groundwater, vapor intrusion and stringent soil leaching to groundwater soil goals.
This capability creates the most value for property owners and investors, as ISTR can achieve unrestricted use status for properties. This means the property can be redeveloped and reused to maximize the owner/developer’s return on investment—there are no limits regarding residential and/or commercial use other than local zoning laws.
- Safe to implement: Thermal remediation systems, when properly designed and implemented, do not pose unacceptable risks to on-site workers or surrounding residents. Unlike other source zone remediation technologies like excavation, ISTR does not require extensive use of heavy machinery, create large piles of exposed contaminated soil that may generate adverse odors and vapor concentrations, or large numbers of trucks transporting waste through neighborhoods.
- Cost competitive: Compared with other rapid remediation options such as excavation and off-site disposal and in situ soil mixing (ISS), ISTR can be very cost competitive. This is especially true if the contaminants are deep, below the water table or below buildings where there are sensitive utilities requiring abandonment and relocation if excavation or ISS is implemented. Typical unit costs for thermal remediation of sites impacted with CVOCs range between $75 and $150/cy, depending on size, depth, volume, contaminant mass, site complexity/constraints, and remedial targets.
- Little community disruption: Unlike excavation and off-site disposal, ISTR does not require large numbers of vehicles or trucks, open excavations and earth moving machinery. It also does not generate significant community traffic, odors, dust or noise. ISTR has been safely and successfully implemented immediately adjacent to and beneath occupied commercial and residential properties.
- No long-term liability: Unlike excavation and off-site disposal or ISS, where liability remains for the contaminants disposed of in a landfill or left in the ground at the site, thermal remediation effectively removes the contaminants from the site and destroys them once and for all. There is no lingering long-term liability potential.
- Adaptable: Thermal remedies can be readily adapted to meet site and project conditions, such as working in and around utilities and buildings, highly variable geologies and groundwater flux, mixtures of COCs, tight timeframes, power and utility availability limitations, depth of treatment, fractured bedrock, difficult to treat COCs, low remedial goals, and challenging health and safety environments and requirements.
ISTR can cost-effectively and reliably address the challenges of brownfield sites and maximize these projects’ potential reuse and value. If you’re considering thermal remediation technology or simply want to learn more, contact our team of experts today.
John LaChance is the Vice President of Development at TerraTherm. In his 30+ year career in the remediation industry, he has worked on a range of project sites, including chemical manufacturing plants, gas stations, oil refineries, railroads, former MGP sites, solvent recycling facilities, grain and feed storage centers, and landfills. Most of these sites have…