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that would be needed to clean up the plume. A Natural Attenuation
<br /> carbon treatment system for air vapors can be
<br /> housed in a small building designed to look like a
<br /> .s Description of the Technology
<br /> garden shed. Monitoring wells are used to check the
<br /> effectiveness of the cleanup system. Natural attenuation refers to the strategy of allow�-
<br /> ing natural processes to reduce contaminant con-
<br /> use at other Locations centrations to acceptable levels. Natural attenuation
<br /> RWT is a recently p
<br /> tl developed groundwater treatment involves physical, chemical and biological processes
<br /> has been used at over 200 sites in which act to reduce the mass, toxicity, and mobility
<br /> technology. It
<br /> of subsurface contamination These processes are
<br /> Europe and over 80 sites in the U.S.
<br /> always occurring and in many cases may reduce risk
<br /> .s
<br /> At the MMR, RWT is being pilot-tested at three to human health and the environment to acceptable
<br /> t =s locations, including the Chemical Spill 10 (CS-10) levels.
<br /> and Ashumet Valley plumes. The purpose of the
<br /> pilot tests at the MMR is to determine the effective- There are several different physical, chemical, and
<br /> technology at capturing and removing biological processes that comprise natural attenua-
<br /> tion.Hess of the to gy p g g
<br /> in Cape God's geologic environment and to These include:
<br /> :�.. VOCs p g g
<br /> compare the effectiveness of RWT with the more . biodegradation breakdown of contami-
<br /> conventional ETR. Preliminary results of the recir- nants by microorganisms in the environment,
<br /> r r _ culating well pilot tests indicate that measuredoften forming non-harmful byproducts like
<br /> D cleaning efficiency is consistent with the pilot test carbon dioxide and water
<br /> -: design and mass removal of contaminants is being .
<br /> ■ chemical stabilization areduction �n con-
<br /> achieved. The pilot test systems currently are being
<br /> e taminant mobility caused by chemical
<br /> evaluted to assess the hydraulic performance of the
<br /> µ processes
<br /> systems for consideration as a component of full-
<br /> scale cleanu alternatives. ■ dispersion the process of mixing that
<br /> occurs when fluid flows through a porous
<br /> e vapor medium
<br /> Injection Blower Treatment
<br /> Unit
<br /> Vacuum ■ sorption attachment of compounds to geo-
<br /> h Blower
<br /> logic materials by physical or chemical
<br /> d •
<br /> M attract i on
<br /> : -.:.::.e`:ll
<br /> .mow:=�`=zA;1;:x•'.:.,. 1''"•"'.^z ,s' w:ate':r::r.' .:,<`s'::
<br /> vault "s _.::�^-•":�c: 2ry;a:s;::»�:..:•::a. =;z✓. . . •
<br /> - =={ • volatilrzatron transfer of a chemical from
<br /> ":::�' ':".:.yY'
<br /> :..- mow.:.:....,........: .. .,7 a,�'..........-:.'�-,::7iJh^�^rit:"�r
<br /> It` 17•.:.::..,f.5, ... KyS .:sFI,-.Y..',.'...fC".55:.:::::`'i
<br /> liquid to vapor; ration
<br /> s.
<br /> ��: q poi evaporation
<br /> t: :a�;wry>£ �.: ::-_.x _.: ,: . .•:_�'��.;... .-
<br /> ... •��� ..:;�^� =:�ra:Y•- :-:;meq;,,-:�...:.w;_,:••'.w .�- .�'_..,....,., �•;..
<br /> Y_ 5"ws e s.yacs} zY's =,a? z '. � ��.s:„�sr µx3?^max
<br /> ��'s''��:�r,�x;.y..:�;;:�,r.r,,a.���:s�-�;.s`��^..;^s.,;,:nom;:n"^^"'sizi::':z::H-Tw;:.;,^-s
<br /> ''y a s �' s ^fir sY s•-
<br /> - :�:�rs � µ- Natural attenuation, by definition, occurs naturally.
<br /> µ,.5..µ�-cr.., .az.•�'-;"• ■
<br /> E':J.x.w:7 :5,^'�.�.._..-. ,;:`x"-:G Y.^.-.:•• .t- �s�. '•..:`r:�..C..w^.fiy:
<br /> n". �_: attenuation^, However, use of naturala specific
<br /> 9
<br /> s c cer
<br /> W_Ss•;%L y}c:s;;•�;:+.:. r.•:r:>aa:x; • 7�
<br /> not do no approach. It
<br /> treatment thing
<br /> `wAR
<br /> :.- ,�:-: .�• method �s
<br /> '�:-� ��.• x - •rte.: �::��:;=._
<br /> involves modeling and evaluating contaminant
<br /> Lt _. R s«�n reduction rates to determine whether it is a feasible
<br /> Upper �
<br />}
<br /> Packer 116 .�. method for plume treatment. The evaluation of
<br /> ` whether or not the treatment method is feasible must
<br /> j also consider existing and future potential risk to
<br /> RechWafion human health and the environment.
<br /> x` Bubble
<br /> Furthermore, to use natural attenuation as a cleanup
<br /> strategy, sampling must be conducted throughout
<br /> 40� VOG Contaminated the process to confirm that degradation is proceed-
<br /> Groundwater
<br /> ing at rates consistent with meeting treatment and
<br /> plume cleanup objectives. Sampling and analysis
<br /> will determine whether natural attenuation actually
<br /> is reducing the mass, toxicity, and mobility of the
<br /> contamination.
<br /> S
<br /> r
<br /> 3 - •
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