In-situ Treatment

As part of its pledge to be “more than a contractor,” EMS strives to provide innovative approaches to projects and technical assistance to customers in meeting cleanup goals by the most economical means and methods possible. EMS has developed expertise with several in-situ remediation technologies with an emphasis on safety, cost reduction, performance and ease of use.

In-situ treatment of contaminated soil and/or groundwater can be achieved by various means and methods. Though injection is a viable and effective process on many sites, the soil treatment method preferred by EMS involves in-situ mixing with excavation equipment and specialty mixing attachments. Because the contamination is treated within the area of contamination (“in-situ”) prior to generation of a waste, this method is especially beneficial when addressing contamination levels in excess of hazardous waste standards.

When comparing in-situ mixing/treatment of soil to more traditional “hog and haul” methods of hazardous waste remediation, in-situ treatment achieves three key objectives at the same time.

  1. In-situ mixing/treatment significantly reduces overall project costs.
  2. In-situ mixing/treatment is fast-acting.
  3. In-situ mixing/treatment prevents the generation of hazardous waste.

Depending on cleanup standards and site parameters, treated soil either can remain on site or can be removed for disposal as non-hazardous waste. In either case, the three objectives noted above are achieved on each and every site where in-situ mixing/treatment is utilized.

EMS utilizes various in-situ remediation technologies when addressing soil and/or groundwater contamination, including the following:

In-situ chemical oxidation (ISCO)

In-situ chemical oxidation (ISCO) involves the rapid, in-situ chemical oxidation of a broad range of contaminants, including both chlorinated solvents and petroleum hydrocarbons. ISCO is a process that involves the mixing or injection of reactive chemical oxidants into soil and/or groundwater for the primary purpose of rapid contaminant destruction (often within days to weeks). This process is most often deployed at sites with relatively high contaminant concentrations in a source area and in down-gradient plumes. ISCO delivers rapid and effective contaminant mass reduction using a solid alkaline oxidant that is activated to a very high performance level through the action of a unique catalytic complex. Once in the subsurface, the combined product produces an effective oxidation reaction comparable to that of Fenton’s Reagent without a violent exothermic reaction.

Metals stabilization/fixation

Metals stabilization/fixation is achieved by mixing proprietary treatment chemistries with soil contaminated with various heavy metals for especially rapid fixation of the contaminants (within hours). For most heavy metals, regulating the pH of the environment is key to controlling leachability. For example, lead leaches on a bell curve, at both high and low pH. So in order to minimize leaching, the treatment additive should not drive up the pH too quickly or too high. EMS uses products that never bring the pH to a dangerous level. We are able to increase treatment efficiency by controlling pH accordingly. In addition, phosphates and other additive chemicals bind to the metals in question, forming compounds that have extremely low solubility and making the treatment essentially permanent (unlike lime).

Enhanced aerobic biodegradation

Enhanced or accelerated, in-situ aerobic biodegradation addresses a wide-range of petroleum hydrocarbons or any aerobically degradable substance. Enhanced aerobic biodegradation is the practice of adding oxygen (an electron acceptor) to soil and/or groundwater to increase the number and vitality of indigenous microorganisms able to perform biodegradation. Treatment products are typically injected into groundwater or applied into open excavations where upon hydration they provide a controlled-release source of oxygen for periods of up to 12 months on a single application.

Enhanced reductive dechlorination

Enhanced anaerobic biodegradation addresses a wide-range of contaminants, including chlorinated contaminants, pesticides, nitroaromatics (explosives and dyes) and inorganics (nitrates and perchlorates). Enhanced anaerobic biodegradation is the practice of adding hydrogen (an electron donor) to soil and/or groundwater to increase the number and vitality of indigenous microorganisms able to perform the naturally occurring process of reductive dechlorination.