Looking at a built-up thermal site with heaters, wells, manifold piping, process gear, and the advanced monitoring systems which can be accessed from anywhere in the world, it can be tempting to wonder how this all came about… Hundreds of engineering details, program logic controlling automatic operation of valves, heating systems, and treatment equipment. Yet, the systems run overnight and on weekends, with nobody there to baby-sit them. Most of the features of a modern In Situ Thermal Remediation (ISTR) site have evolved over a period of less than 25 years. I will try to explain the evolution here.
Chemicals become mobile and vaporize when heated – this has been knows for centuries, and formed the basis for distilling alcohol (a trick homo sapiens seemed programmed to learn shortly after learning to control fire), and more recently when cracking and distilling oil into gasoline, diesel and other useful hydrocarbons. So it is no surprise that some of the core know-how comes from the oil industry.
When the price of oil dropped in the 1980’s, so did the cost of smart engineers and geologists. This coincided with the US Superfund program being developed, asking for clean-up of major government sites, which also marked the beginning of regulations requiring clean-up of industrial sites owned by private parties. As a result, hundreds of well-trained staff with oil field experience started migrating towards environmental challenges, and a decent pay.
The Dutch had made early attempt to heat soil and clean it – but when several universities and national laboratories in the US started developing their brands of ISTR and documenting it, things sped up. Most noteworthy were:
- Kent Udell, a young and eager professor at UC Berkeley, who explained the logic of chemical behavior and through the work of many students, worked out most of the challenges of making the chemicals move and be captured, while not making the problems worse.
- Lawrence Livermore National Laboratory (LLNL). Here, Robin Newmark, Roger Aines, and a large group of researchers studied chemical behavior, and conducted the first well documented deep ISTR project at LLNL’s gas pad in Livermore, California, publishing a four-volume state-of-the-art report on how to do it in 1995. Both Steam Enhanced Extraction (SEE) and Electrical Resistance Heating (ERH) were refined and used together in what was named Dynamic Underground Stripping (DUS).
- Pacific Northwest National Laboratory (PNNL/Battelle). Six- and three-phase heating technologies were developed and demonstrated.
Many other researchers and firms contributed, and early demonstrations were conducted at Sandia National Lab and Savannah River Site, among others.
The process equipment came mostly from oil-field providers, since engineers had been processing hot liquids and vapors for decades, both in oil fields where steam drive and soaking was used, and at refineries. Some corrosion challenges related to chlorinated solvents had to be overcome, and heat exchangers and related equipment were upgraded for acidic conditions.
In the late 1990’s, things started speeding up. Southern California Edison, assisted by LLNL and Kent Udell, as well as Hank Sowers (SteamTech), implemented a large-scale SEE remedy at their Pole Yard site in Visalia, CA. The site eventually met all remedial goals and was de-listed from the National Priorities List (NPL), after removal of close to two million lbs. of creosote from the subsurface. The major developers behind the project are shown below:
Several commercial ISTR vendors appeared: SteamTech Environmental Services (implementing SEE), Current Environmental Solutions (later separated into CES and TRS; implementing ERH), McMillan-McGee (implementing Electro-Thermal Dynamic Stripping Process™ (ET-DSP™), a form of ERH) and TerraTherm (initially a Shell subsidiary for In Situ Thermal Desorption (ISTD) development, now a privately held firm implementing ISTR). Since the turn of the century, the commercial companies have all improved their ability to design, predict, and implement ISTR, and the volume of work has increased steadily.
A number of oil companies have employed thermally enhanced oil recovery using steam and other technologies extensively since the 1960s. Shell’s work in oil shale was noteworthy in that higher temperatures were needed to produce oil from the tarry bitumen. Led by George Stegemeier and Harold Vinegar, Shell developed thermal conduction heating as a remediation technology during the 1990s and named it In Situ Thermal Desorption (ISTD). After donation of the ISTD patents to the University of Texas, the current TerraTherm, Inc. was formed in 2000.