REMEDIATION
OF TOXIC VAPORS RESULTING FROM PRODUCT SEEPS
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DEWATERING
THE WATER TABLE AND VACUUM EXTRACTION
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By
the earthDr!
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It
is necessary to incorporate both pumping of the ground water and soil vapor
extraction to remedy vapors resulting
from seeps of separate phase product (use the back button on your browser
or click on the Table of Contents to relocate yourself back to this page
should you choose to review the earlier page). Don't assume that the objective
of pumping of ground water for this situation is the same as for remedying
vapors from seeps of dissolved product
The figure to the left depicts a simplified version of both dewatering of the water table and soil vapor extraction. A recovery well is used to dewater the water table in this figure. A blower is used to pull a vacuum and any toxic vapor clouds from the soil atmosphere. It operates similar to an exhaust fan. A vacuum is applied to the unsaturated zone to reduce soil atmospheric pressure below atmospheric pressure. When this is achieved, air will flow from the basement into the soils surrounding the basement. Air flow is reversed from that depicted on the previous webpage illustrating venting of the soil atmosphere into a structure. It is this reversal of air flow that will prevent vapor clouds from entering a basement or crawl space. Air flow is now from the basement into the soil atmosphere. It doesn't make sense to place an exhaust fan in a basement window and exhaust the basement air to the outside atmosphere, because this action would decrease the basement atmospheric pressure; thereby, further increasing the difference between soil atmospheric pressure and the basement atmospheric pressure driving more contaminated air from the soil atmosphere into the basement. |
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EMAIL:
earthDr@earthDRx.org |
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