In the example provided, hazard quotients for exposed wildlife and humans are calculated by the model for three scenarios: historical case of mercury-contaminated sediments, required clean-up levels to protect the most sensitive species, and background conditions.
But until the risk is known — how many parts per million or per billion in water, or land or air have been shown to harm human health — regulators can do relatively little in the way of requiring clean-ups.
PDCs also leave a deposit, which may require clean-up if site rehabilitation is undertaken.
The reports vary in seriousness and not all require clean-up action from the EPA.
As a result, there are numerous sites in the world that require clean-up of soils and sludge.
The underpinning component of the model is a scalable clean-up response framework, which identifies and progressively includes more urban surfaces (e.g., roofs, and roads) requiring clean-up with increasing tephra thickness.
Methods such as liquid liquid extraction (LLE) or solid-phase extraction (SPE) have been used for isoflavone extraction and purification, because biological samples require clean up [ 27, 28].
Amigos Bravos won a settlement in May 2011 against the U.S. EPA and Los Alamos over discharge permits that will require clean up of a number of sites, increase monitoring, and install pollution control measures (van Buren 2011).
For the first time, New Yorkers were required to clean up after their dogs.
Remember how awful the streets were before owners were required to clean up after their pets?
Mining companies are not required to clean up after themselves, or pay royalties the way oil, gas and coal producers do.
