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  • EPA’s Superfund program protects citizens from the dangers posed by abandoned

  • or uncontrolled hazardous waste sites. In the past, getting these

  • sites cleaned up often required a significant outlay of energy and non-sustainable resources.

  • The traditional approach for contaminated soil has been to excavate

  • the material and haul it away. Unfortunately, this operation has a domino effect,

  • by disturbing uncontaminated areas, including the clean fill needed to backfill the excavation.

  • Now EPA has introduced a Green Remediation initiative for these sites

  • that considers the environmental effects of the remedial strategy early in the process,

  • and incorporates options to maximize the net environmental benefit of the cleanup.

  • From the selection and design of the remediation technology, to the management of

  • on site activities, to the use of energy conservation and alternative sources of clean energy,

  • Green Remediation helps save natural resources and taxpayers dollars.

  • (Car Driving)

  • Outside the small Virginia town of Crozet, EPA is doing just that,

  • by using phytoremediation to remove arsenic contamination from a residential property.

  • Phytoremediation uses specially selected plants to remove or reduce the risk of

  • contaminants in the soil, water, sediments, and air.

  • The 2 acre site, a former orchard, is contaminated with arsenic

  • which is a by-product of pesticide application on fruit trees.

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  • Myles Bartos: Prior to 1972 there was legal application of pesticides, lead arsenates,

  • DDT, DDE and DDD. EPA banned them in 1972. However, there’s a lot of

  • orchards that still had their product on the soils. And since then, a lot of these orchards

  • have been sold off and developed into residential properties.

  • Arsenic doesn’t break down like DDT, DDE and DDD does, so that is a little more

  • pervasive in sticking around. It’s not very mobile so it actually stays

  • in place where it is. And that’s actually helping us because we don’t have to go chasing

  • it to deep depths. Essentially the top roughly zero to six inches are contaminated.

  • The contaminated areas of the hillside are used by adults, children

  • and pets on a daily basis. Because Arsenic is a known carcinogen, mutagen,

  • and is detrimental to the immune system, the soil needed to be cleaned up.

  • Phytoremediation was chosen because if conditions are favorable,

  • the technology can be effective, while having minimal impact on existing topography and the ecosystem.

  • Phytoremediation is also considered an In-Situ, or in place remediation approach, which

  • means the contaminated media isn’t transported off site. And since plant cultivation

  • and harvesting are relatively inexpensive processes, phytoremediation has significant

  • cost saving advantages compared to traditional clean up methods.

  • Scott Fredericks: Superfund has been around 25 years. Weve learned a lot about,

  • if you dig and haul, it’s a very energy-intensive operation. You have huge

  • equipment that takes a lot of money to operate.

  • Instead of bringing in a lot of heavy equipment, being very disruptive knocking down

  • all these trees, hauling off all this dirt and putting it someplace else,

  • and then trying to find some clean soil to bring back in here, theyre trying to do an

  • In-Situ extraction using these ferns.

  • The ferns being planted were developed at the University of Florida and licensed to

  • Edenspace, a leader in the use of plants for environmental protection and renewable fuels

  • Michael Blaylock: Weve done a lot of work looking at different plants and their ability to

  • accumulate arsenic. And we found that really only ferns in this particular

  • genus - Pteris ferns - accumulate arsenic. And they take up arsenic to a very high concentration.

  • They tolerate high arsenic concentrations in their leaves and they do a remarkable

  • job of extracting it from the soil.

  • In fact, the hyper-accumulating 'Victory' variety of Pteris vittata (terrace vit-tah-ta)

  • sold by Edenspace, under the label Edenfern, holds concentrations greater than

  • 200 times more than other plants tested for Arsenic phytoremediation,

  • and is adaptable to conditions in a variety of climates.

  • USEPAs relationship with the property owner also helped in choosing phytoremediation.

  • Jim Dugan: I feel a real close connection to the property. And I wanted to be at the

  • property sort of like if you have a patient in the hospital. You want to be there with that person.

  • And I consider this land my responsibility, and I have been able to work with the EPA members.

  • Theyre really friendly and they don’t mind my so-called interference.

  • Getting the job done is relatively simple. Areas of the hillside with elevated levels of

  • arsenic were mapped into 30 by 30 foot plots, then tilled to a depth of approximately four inches.

  • Michael Blaylock: The goal here is to be able to optimize plant growth.

  • Because if we get the plant roots to develop well, and get the plants to grow well,

  • they will take out more arsenic from the soil. So we want to do everything we can to

  • prepare the site and to try to optimize the plant growth.

  • Myles Bartos: We did soil composition testing to see what sort of nutrients we need to apply.

  • In this case we did a very mild nitrogen-based fertilizer, slow-release formula,

  • put a little lime in to neutralize some of the soil. Once we do that, we lay down landscape fabric,

  • and cut holes in it in a one square foot area. And in this particular case youre doing 30 X 30 grids.

  • Michael Blaylock: Then we transplant the ferns in. And from then on out it’s a matter of

  • keeping them wet until the roots get established in the soil. And providing the shade

  • that they need in an environment like this, that’s easy because of the trees.

  • In the few areas where direct sunlight could reach the ferns,

  • 60% shade cloth was placed over the plot to improve plant growth.

  • For irrigation, the plots were divided into two systems. The first system utilizes a

  • spring at the top of the hill close to the residence which gravity feeds into a storage tank,

  • which in turn gravity feeds the fern plots.

  • The other half were going to use a solar panel pump. A low pressure drip tape irrigation

  • was installed to deliver fresh water to the ferns during dry spells. During periods

  • of adequate rainfall, water from the spring will be diverted and recovered into

  • the storage tanks for later use.

  • The ferns will be grown for approximately five months or until night temperatures drop

  • below freezing and plant growth and biomass production ceases.

  • The fern biomass will be harvested, and then sampled for arsenic content.

  • Because arsenic levels in the harvested plants are expected to be below prescribed levels,

  • they can then be disposed of in a municipal landfill.

  • Soil sampling will be conducted at the end of the growing season and compared

  • to pre-planting samples to determine the ferns effectiveness.

  • Michael Blaylock: In some areas the arsenic concentrations are higher and it will take more

  • than one season we anticipate. But for a large part of this site,

  • we think we can do in it one year.

  • Phytoremediation is idea for targeting small areas like the 30 by 30 plots at the Crozet

  • sites. The technology does have limitations though. At some sites contamination may

  • just be too deep for plant roots to reach. But under the right conditions,

  • phytoremediation is a win-win for clean up teams and the public.

  • Michael Blaylock: People generally like the idea of being able to use a plant to take contamination

  • out of the soil, that’s something that has a lot of public appeal and I get a lot

  • of positive feedback for it.

  • Scott Fredericks: And nothing succeeds like success. So this site is important,

  • I think, because it represents what’s it is were seeing more of across the country in other states,

  • especially on the west coastold orchards that are being built upon,

  • people retiring on them or theyre just building homes as part of urban sprawl.

  • With this technology, It’s very low impact and youre not using a lot of energy.

  • What were using here are sustainable, or clean energy forms. Were using solar panels

  • to drive our pumps for the drip irrigation system and were

  • using a minimal amount of energy.

  • Myles Bartos: The goal here is not to be green, but it’s a really good secondary thing.

  • Our goal is to protect public health and the environment.

  • This happens to be an alternative technology that will do that with less waste and a

  • greener atmosphere. So it actually goes along with the EPA initiative

  • of going green and it also achieves our tasks within the removal progra.

  • (music playing)

(music playing)

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クロゼット、バージニア州のファイトレメディエーションプロジェクト (Crozet, VA phytoremediation project)

  • 168 14
    QAM Chen に公開 2021 年 01 月 14 日
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