A team from Burns & McDonnell is testing a new delivery technique for a proven oxidation technology that could reduce the cost, extend the duration and boost the overall effectiveness of groundwater remediation efforts.
Manufacturing voltage regulators, assembling ignition systems and otherwise helping motor vehicles get off to a good start takes more than coiled wire, electronic components and attention to detail.
It also requires industrial-strength chemicals to keep the factory and its products clean. And because such cleansing operations can leave dirty problems behind — typically solvents, usually underground — site owners sometimes rely on injected oxidants for their time-consuming and often expensive contaminant cleanups.
A team from Burns & McDonnell is testing a new delivery technique for a proven oxidation technology that could reduce the cost, extend the duration and boost the overall effectiveness of groundwater remediation efforts. The approach could significantly reduce treatment time and cost at numerous manufacturing and maintenance facilities, former dry cleaners and military installations.
"You have a lot of sites that really require attention, but funding is scarce, especially in this day and age," says Walter McClendon, an associate geologist in the Environmental Group at Burns & McDonnell. "This type of technology would be an effective, economical alternative for many of our clients."
This innovative process breaks new ground with a simple-yet-effective combination of components: an oxidant commonly used for groundwater treatment, and a more common wax material. Together, they are producing promising results now being confirmed during a yearlong pilot project in Independence, Kan.
At the site of a former automotive parts manufacturing facility, Burns & McDonnell is overseeing the innovative use of potassium permanganate. The permanganate (chemical formula KMnO4) is an oxidant that typically is injected into groundwater to transform toxic solvents and other components into less-harmful products.
For this pilot project in Independence, Burns & McDonnell is giving permanganate a longer life while reducing delivery costs. Technology developed by Carus Chemical Co. and Specialty Earth Sciences allows a granular form of the oxidant to be suspended inside columns of paraffin wax; the columns, each 3 feet long and 2 inches in diameter, are then installed below ground using direct-push hydraulic equipment.
Suspending the granules provides time-release capabilities expected to stretch the oxidant's effectiveness to as long as three years, an improvement when compared with injections that otherwise break down solvents for six months to a year.
"Aqueous permanganate solutions really give you a steady reduction in your contaminant, but they dissipate quickly and are expensive to inject because of the large volumes of oxidant that must be mixed and pumped," McClendon says. "We were looking for something that would give us the same bite but over a longer period of time, and at a greatly reduced cost."
Burns & McDonnell found the solution in the colorless wax solids, which take on a deep purple tint when saturated with potassium permanganate. "They're like candles," McClendon says.
At the site of the former automotive parts manufacturing facility, 48 of the candles were installed to as deep as 11 feet underground, creating an active oxidant treatment barrier. Below the surface the candles interact with trichloroethene, a solvent, that has leeched into the groundwater, a legacy of contamination from cleansing of regulators, ignitions and related equipment for more than three decades following the factory's opening in the 1960s.
The candles' cost-effectiveness and convenience appear to be major benefits, too. Using injection technology at the former manufacturing facility site would have cost at least $80,000. Crews also would have needed larger equipment, such as a stationary drilling rig that would, depending on the type, have taken up as much space as a tractor-trailer truck. Using candles reduces such needs. Direct-push equipment is both small enough to fit in the bed of a pickup and portable enough to be taken into buildings. The pilot project's expenses are down to $20,000 — well below the cost and disruption that would have been brought on by yet another alternative, excavation and disposal.
"We wanted a cost-effective remedial alternative," McClendon says. "We wanted to do it in situ because a lot of times, the site is a former business that's in a highly populated and congested area. In downtowns, in small towns, you can't just go in there and inject the plume or dig and haul it away. You would be injecting or digging up half a street."
Data from the pilot project is being compiled for review later this year, and there will be plenty to look at: Groundwater contamination from trichloroethene has hit 150,000 micrograms per liter in some areas at the site, well above the maximum contaminant level of 5 micrograms per liter as set by the Environmental Protection Agency.
State regulators will receive the final report, and McClendon is confident that the study's conclusions could help future clients break up stubborn solvents saturating groundwater beneath dozens, hundreds, even thousands of sites.
"We're searching for a low-cost alternative," McClendon says, "and if this works this would be the perfect solution for addressing contaminant source areas and spot treatments."
For more information, contact Walter McClendon, 816-822-4357.