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Innovative Safety Controls for Fenton’s Remediation: A
Case History
R.
Thomas Numbers, P.E., Vice President, MECX,
LLC, 9189 Red Branch Road, Columbia, MD 21045 Tel:
410-772-3303, Fax: 410-772-3304, Email: thomas.numbers@mecx.net
Richard T. Cartwright, P.E., CHMM, Vice President, MECX,
LLC, 8096 Clarherst Drive, East Amherst, NY 14051, Tel:
713-412-9697, Fax: 713-585-7049, Email: richard.cartwright@mecx.net
An
innovative and safer chemical application control system
was recently utilized during the injection of CleanOX®
reagents at a former chemical manufacturing facility. Basis
of the CleanOX® Process is the well-known
Fenton’s Reaction wherein hydrogen peroxide reacts with
ferrous ions to produce hydroxyl free radicals and
superoxides in an acidified aqueous medium containing the
contaminants. Resultant reagents are extremely powerful
oxidizers that progressively react with organic
contaminants through a series of oxidation reactions.
During the process, the organic constituents are converted
to progressively less complex and shorter chemical chains,
ultimately yielding carbon dioxide and water.
Fenton’s
reagents are applied directly into the area of concern
through injection wells. The reagents then treat
contaminated groundwater and saturated soil in-situ,
producing no waste streams that require permitting,
treatment, or disposal. Principal advantage of the CleanOX®
Process over other in-situ treatments is the very rapid and complete destruction of
organic contamination in groundwater and saturated soil.
The CleanOX® Process is primarily directed
toward remediation of dissolved-phase contamination and
has also been applied to address free-phase product.
The
innovative chemical application control system optimized
the injection rate of CleanOX®
reagents. This reduced the total volume of potentially
hazardous materials injected into the subsurface
environment. Although over 200 applications, in over 26
states, of the CleanOX® reagents have been
successfully completed without a recordable OSHA incident,
there is a definite need to constantly improve the safety
of this innovative remediation technology. Based upon the
case history hereby cited, a quantum jump in hazardous
materials safety was achieved. Thus, the authors recommend
that when applying Exothermic Fenton’s Reactions for the
clean-up of soil and groundwater that suitable chemical
application controls be utilized.
Lessons
Learned From The Application of In-Situ Oxidation
Technologies: Practical Evaluation of Seven Projects
michael
Doherty, P.E., Woodard & Curran, Inc., 35 New England
Business Center, Andover, MA 01810 Tel: 978-557-8150, Fax:
978-557-7948
Christopher Miller, P.G, Woodard & Curran, Inc., 980
Washington Street, Ste 325, Dedham, MA 02026 Tel:
781-251-0200, Fax: 781-251-0847
The
authors have utilized potassium permanganate (KMnO3)
and other oxidants at a wide range of contaminated
properties while implementing in-situ chemical oxidation
remediation technology.
The purpose of the applications was to destroy
various contaminants including chlorinated solvents,
petroleum hydrocarbons, and ammonia.
This
presentation will summarize the lessons learned, problems
encountered and overall cost and technical effectiveness
of utilizing in-situ oxidants via various
addition methods and project conditions.
The speakers will discuss the practical lessons
learned from applications of these technologies from
different applications of oxidation chemicals to address
saturated zone contamination.
Methods
of applying in-situ chemical oxidation chemicals to
subsurface soils and groundwater have included “soil
mixing” approaches to address soil contamination,
“inject and leave” approaches for cost effective, low
impact polishing of groundwater, and an aggressive
“inject and control” approach to enhance the operation
of an existing groundwater treatment system.
The pros and cons of each type of application will
be presented.
The
target applications areas have included residential
neighborhoods, within and underneath airport hangars,
underneath warehouses and professional buildings, in
support of excavation and disposal activities and in
conjunction with groundwater pump and treat activities.
Specific lessons learned in applying this
technology will be discussed.
Total
project costs to utilize in-situ oxidation have been less
than $100,000
in six of the seven sites discussed.
The cost components (pre-application studies,
infrastructure, chemical, application, monitoring, etc.)
are evaluated and presented on a cost per application and
cost per site basis.
The cost effectiveness of utilizing these
technologies to address saturated zone contamination at
small to medium sized sites will be presented and compared
to other remediation technologies and approaches.
In-situ
chemical oxidation is an effective remedial technique that
may be used in a range of applications.
However, our experience also shows a range of
success in achieving remedial goals.
In-Situ
Chlorinated Solvent Remediation using a Circum-Neutral pH
Modified Fenton’s Process
Prasad
K. Kakarla, P.E., In Situ Oxidative Technologies, Inc., 51
Everett Drive, A-10, West Windsor, NJ 08550, Tel:
609-275-8500, Fax: 609-275-9608, Email:
pkakarla@insituoxidation.com
Richard S. Greenberg, Ph.D., In Situ Oxidative
Technologies, Inc., 51 Everett Drive, A-10, West Windsor,
NJ 08550, Tel: 609-275-8500, Fax: 609-275-9608, Email:
richard.greenberg@ewma.com
A
Fenton-based chemical oxidation process was used to
conduct a remedial treatment program at a former dry
cleaners site in Northern Florida.
The patented process employs a modified Fenton’s
reagent (ISOTECSM Process) that has the
capacity to function under natural subsurface pH
conditions (i.e. pH 5-8) and effectively disperse within
the subsurface. The
chemical amendments allow the formation of hydroxyl
radicals, the key oxidants in Fenton’s reaction, to be
delayed until H2O2 has spread
throughout the plume.
Additionally, the process also produces reducing
superoxide radicals and hydroperoxide anions that promote
increased desorption and degradation of recalcitrant
contaminants. The contaminants treated at the former dry
cleaners site included Tetrachloroethene (PCE),
Trichloroethene (TCE) and cis-1,2-Dichloroethene (cis-DCE)
at concentrations exceeding 1,850 ug/l. To establish whether the ISOTEC process could treat the
site-specific contaminants and to determine the optimum
oxidation conditions based on the contaminants detected, a
preliminary laboratory bench-scale study was conducted.
The results of the study showed the reagent to be
effective in achieving over a 99% destruction of total
volatile organic compounds (VOC’s) in the groundwater
and over a 94% reduction in the soil-slurry samples.
Based
on the positive bench scale results, the field treatment
program ensued, targeting a portion of the plume that
historically showed the highest levels of chlorinated
solvent compounds exceeding the applicable Florida
Department of Environmental Protection (FDEP) groundwater
quality criteria. The majority of the chlorinated solvent
contamination was present below 8 feet bgs to a depth of
up to 16 feet bgs with the highest concentrations located
between 10-12 feet bgs.
A total of forty (40) direct-push points spaced no
more than 25 feet from one another were installed in a
grid fashion to target two separate depth intervals
ranging from 8-12 feet bgs and from 12-16 feet bgs.
The injection activities were performed over two
separate injection events spread approximately six (6)
weeks apart. Results
of the treatment program indicated a 72 percent reduction
in total chlorinated contamination detected in the site
groundwater following the first injection event; the
reduction increased to 90 percent following the second
injection event. A
one-year post remediation FDEP quarterly groundwater
monitoring program is currently ongoing to evaluate site
closure options.
Fuel
Oil Spill Remediation with Nanno to Microbubble
Peroxide-Encapsulated Ozone Pulsed Perfusion
William
B. Kerfoot, K-V Associates, Inc., 766 Falmouth Road, Unit
B, Mashpee, MA 0264Tel:
508-539-3002, Fax: 508-539-3566, Email:
wbkerfoot@kva-equipment.com
Special
laminar Spargepoints® and gas/liquid supply equipment
allow hydroperoxide to coat nanno- to micro-sized gas
bubbles containing air/ozone mixtures.
Bench-scale tests showed the use of thin-layer
microbubbles containing ozone with a coating of
hydroperoxide improves the rate of oxidation of certain
polyaromatic hydrocarbons (PAHs) and branched linear
alkanes commonly found in weathered fuel, when compared to
ozone or hydroperoxides used separately or in combination
without ultra fine bubble formation.
During injection of the gas fraction through the
laminate membrane, the peroxide is siphoned by negative
pressure to form coatings on the ultra-fine bubbles.
The coating creates a high surface area film of
reactive hydroxyl radicals through which aliphatic and
aromatic VOC compounds are drawn by Henry’s Law of
liquid-gas partitioning. The process was then applied to a fuel oil spill.
The site was a seaside motel with a fuel line leak,
combined with a possible old tank bottom release from an
abandoned tank. The
extent of the spill was delineated by soil and water
sampling with push-probes and monitoring wells.
Using on-site ozone generation and peroxide
addition units powered by house current, a wallmount
microsparging system supplied oxidant to three laminar
Spargepoints® and a conventional microporous Spargepoint®.
The microbubbles were pulsed through the sandy
formation during sequential operation.
Soil and groundwater analyses were conducted on oil
fractions following the Massachusetts EPH procedure,
separating weight fractions of aliphatics and aromatics.
A mass balance analysis was performed to relate the
removal of oil fractions to mass of oxygen delivered.
Bacterial growth was measured across the site at
the end of treatment and sensitivity to ozone determined.
Massachusetts DEP requirements for closure were
reached after 4 months of operation.
Additional sampling showed no indication of
rebound.
Nanno/Microbubble
Ozone Perfusion for Brownfields Remediation
William
B. Kerfoot, K-V Associates, Inc., 766 Falmouth
Road, Unit B, Mashpee, MA
02649, Tel: 508-539-3002,
Fax: 508-539-3566, E-Mail: wbkerfoot@kva-equipment.com
Redevelopment
Remediation often involves converting contaminated former
industrial property to residential standards for soil and
groundwater. The treatment system must be able to be used in heavily
urbanized areas, adapt to ongoing building, and be time
dependent. Encountered
contamination is often a mixture of chlorinated solvent
and petroleum spills.
Financing can be phased to lots renovated in
multi-lot developments.
A former industrial/commercial area in Falmouth,
Massachusetts, contained laundry and dry cleaning
facilities from 1904 to 1963.
Large-scale cleaning operations commenced during
World War II, when property operations were utilized
primarily by the Federal Government for cleaning military
garments. Dry
cleaning solvents, gasoline, and #6 bunker fuel oil were
stored at the property in underground storage tanks (USTs)
over the years. Two separate groundwater and soil contamination plumes of
predominantly tetrachloroethene (PCE) and petroleum
hydrocarbon-based MCP exceedances of aromatic hydrocarbon
chains n-C9 and n-C10 and aliphatic
hydrocarbon chains n-C9 and n-C12
occurred on the property.
The region is subject to commercial/urban GW-2
standards (non-drinking water).
The regions were treated with nanno/microbubble
ozone perfusion. Certain
source areas received ozone with peroxide-coated bubbles
applied through Laminar Spargepoints®.
Razing of the buildings required relocation of the
treatment system to a mobile unit to accommodate on-going
development. The
extent of subsurface concrete and metal structures
encountered during site excavation was exceptional and
required unexpected effort for trenching in of lateral
piping to injection locations.
Soil and groundwater probing was performed to
confirm extent of treatment and to reduce time delays of
groundwater flow for monitoring.
The site remediation was started on January 8,
2002, and was completed in August, 2002, a total of eight
months’ time to achieve a Class A-2 Response Action
Outcome (RAO).
Chemical
Oxidation of Groundwater Plumes
Dale E. Markley, Philip Environmental Services
Corporation (PESC), 210 Sandbank Road, Columbia, IL 62236,
Tel: 618-281-1540, Fax: 618-281-5120, Email: dmarkley@contactpsc.com
PESC has performed site
remediation of gasoline and chlorinated solvent releases
at many sites. For a site that was a former glass manufacturing facility, closed in
the early 1990s, Trichloroethene and Methylene Chloride
were used in the manufacturing process at the facility.
Characterization of the extent of volatile organic
compounds revealed contamination of the shallow aquifer
located in alluvium beneath the site at levels of
approximately 600 ppb Trichloroethene and 560 ppb
Methylene Chloride. The impacted water was encountered at depths ranging from 25
to approximately 40 feet below ground surface. PESC
installed wells to define the groundwater plume extent and
followed an Agency approved work plan to evaluate natural
attenuation. Following
one year of monitoring, accelerated methods of chlorinated
solvent degradation were evaluated and in situ chemical
oxidation (ISCO) was recommended to the Agency. ISCO
consisted of injection of a surfactant to assist in
dispersion of the oxidant followed by injection of a 25
weight percent solution of hydrogen peroxide.
This procedure was performed on 42 probeholes to 40
feet below ground surface. The PESC injection process uses a 10,000-psi high-pressure
lance that cuts it’s way to the desired injection depth. This reduces the cost of mobilization of drilling or
direct-push equipment to reach the desired depth. The
method works well in silt, clay and fine sand soil types.
Confirmation groundwater samples within the treatment area
footprint were collected approximately 4 weeks after
performing ISCO. An
evaluation of results indicated a 70 to 80 percent
reduction in chlorinated organic compounds in groundwater.
Concentrations were reduced to 170 ppb for Trichloroethene
and 80 ppb for Methylene Chloride.
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