|
TO BUSINESS AND ENVIRONMENTAL EDITORS: |
Project to Marshal Microbes Against Pollution |
|
PHOENIX, ARIZONA, Jun. 27 -/E-Wire/-- A technologically advanced project to encourage bacteria to literally eat the soil and groundwater clean at a contaminated site in California has been launched by AMEC's Earth & Environmental operations.
|
Under the two-year project, microbial "food" such as molasses, whey and vegetable oil, as well as fertilizer and calcium peroxide, will be used to stimulate microbial degradation of pollutants at a former laundry and dry cleaning plant. Pollutants include hydrocarbons such as diesel fuel, Stoddard solvent and motor oil in one area of the site and chlorinated solvents such as perchloroethylene (PCE) and trichloroethylene (TCE) in another area.
|
"It is ironic that some of the same substances that were washed from clothes by the laundry now will be used to remove an environmental stain," says AMEC Project Manager Richard Sturm. "By using such every-day substances, we are able to perform environmental clean-ups effectively and at a fraction of the cost of our competitors."
|
The plant operated from the early 1900s until 1981 in Salinas. The site, on Gabilan Street, has become a concern to the community because Salinas relies on groundwater for its drinking water and the contaminants pose a future risk to the drinking-water aquifer. An investigation by AMEC found that contaminants have reached groundwater-bearing zones beneath the site, but thus far not deeper zones, including the aquifer from which the city obtains drinking water. Mission Linen Supply, which purchased the plant in 1966, reacted as a responsible community member and agreed to an immediate cleanup.
|
As a first step, approximately 3,000 cubic yards of hydrocarbon-contaminated soil have been excavated and decontaminated off-site. This was accomplished with a process called "low-temperature thermal desorption" in which hydrocarbons vaporize when soil is heated.
|
Now, hydrocarbon contamination below the groundwater table is being addressed with a biostimulant-delivery system developed by AMEC. This involves the injection of calcium peroxide and fertilizer into the saturated zone beneath the excavation. Microbes can flourish only when electron donors and electron acceptors are abundant. Calcium peroxide is an oxygen-releasing electron acceptor that speeds the biodegradation of hydrocarbon fuels, which are electron-rich donors. Fertilizer adds nitrogen and phosphorous, which are necessary for cell growth.
|
Chlorinated solvents PCE and TCE will be tackled next by applying either molasses or whey to the soil and by injecting molasses or vegetable oil into groundwater. These materials serve as microbial "food" because they are electron donors, while PCE and TCE, as oxidized organic contaminants, are electron acceptors. Under this technique, microbes -- fueled with a constant supply of electrons from the molasses, for example -- will use up any oxygen or other electron acceptors that may be present as long as contact with the atmosphere is prevented. The microbes then will go after the oxidized contaminants as electron acceptors. Once the oxidized contaminants receive electrons, they will be chemically changed and rendered less toxic and often harmless.
|
AMEC operates 90 Earth & Environmental offices in North America. These offices offer a wide variety of services covering environmental consulting, geotechnical engineering, materials testing, and water-resources planning.
|
AMEC is a global leader in the provision of services and engineering solutions to the world's infrastructure, manufacturing and process industries. The company has annual revenues in excess of $6 billion and operates from offices in more than 40 countries. www.amec.com.
|
Mission Linen Supply is a major commercial laundering company with facilities in California, Oregon, Nevada, Arizona and Texas. Mission employs approximately 100 people in Salinas at plants on Kern and Market streets.
|
Richard Sturm and Dr. Michael Piotrowski developed the remediation plan. On-site remedial activities are being managed by Rick Singer (Colorado Springs), with assistance from Ryan Van Pelt (San Rafael).
|
