WI0800038_Other Correspondence_20031028

North Carolina Department of Health and Human Services
Division of Public Health • Epidemiology Section
1912 Mail Service Center • Raleigh, North Carolina 27699-1912
Tel [phone] • Fax [phone]
Michael F. Easley, Governor
October 28, 2003
MEMORANDUM
TO: Evan Kane
Groundwater Section
FROM: Luanne K. Williams, Pharm.D., Toxicologist
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Carmen Hooker Odot,Secreta ,
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Medical Evaluation and Risk Assessment Unit
Occupational and Environmental Epidemiology Branch
North Carolina Department of Health and Human Services
SUBJECT: Use of Hydrogen and Helium for Bioremediatioin of Chlorinated Solvent
Contaminated Groundwater at the Maintenance Complex for Amphibious
Vehicles at Camp Lejeune Marine Corps Base in Camp Lejeune, North
Carolina.
I am writing in response to a request for a health risk evaluation regarding the use
of hydrogen and helium for bioremediatioin of chlorinated solvent contaminated
groundwater at the maintenance complex for amphibious vehicles at Camp Lejeune
Marine Corps Base in Camp Lejeune, North Carolina. Based upon my review of the
information submitted, I offer the following health risk evaluation:
WORKER PRECAUTIONS DURING APPLICATION
1. Some effects reported to be associated with the chemicals present in the product
following short-term exposure are as follows:
• Skin contact with helium or hydrogen can cause severe burns and frostbite to
the skin (Hazardous Substance Fact Sheet by Micromedex TOMEs Plus
System CD-ROM Database, Volume 58, 2003).
• Significant inhalation exposure to helium or hydrogen can cause suffocation
from lack of oxygen. Symptoms include dizziness, weakness, nausea,
vomiting, loss of coordination and judgment, increased breathing rate, and
loss of consciousnes and death (Hazardous Substance Fact Sheet by
Micromedex TOMEs Plus System CD-ROM Database, Volume 58, 2003).
2. Hydrogen is a highly flammable liquid or gas and a dangerous fire and explosion
hazard. Hydrogen must be stored to avoid contact with heat, flames, sparks,
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() Location: 2728 Capital Boulevard • Parker Lincoln Building • Raleigh, N.C. 27604 An Equal Opportunity Employer

oxidizing agents (e.g., perchlorates, peroxides, permanganates, chlorates, nitrates,
and bromine), explosives, liquid nitrogen, ozone, palladium, catalysts, lithium,
strontium, barium, and calcium since violent explosions may occur (Hazardous
Substances Data Bank by Micromedex TOMEs Plus System CD-ROM Database,
Volume 58, 2003).
3. In order to reduce the risk of injury, certain precautions should be followed when
applying the product:
(a) If the product is released into the environment in a way that should result
in a suspension of fine solid or liquid particles (e.g., grinding, blending,
vigorous shaking or mixing, or opening of a container where the internal
pressure may be different from ambient pressure), then proper respiratory
protection should be worn. The application process should be reviewed
by an industrial hygienist to ensure that the most appropriate
respiratory equipment is worn if needed.
(b) Persons working with this product should wear goggles or a face shield,
gloves, and protective clothing. In order to prevent contamination of the
worker's home and other work areas, the gloves and protective clothing
should only be worn in the application area and should never be taken
home.
(c) Eating, drinking, smoking, handling contact lenses, and applying
cosmetics should not be permitted in the application area during or
immediately following application.
(d) Workers should wash their hands after applying the product.
4. Safety controls should be in place to ensure that the check valve and the pressure
delivery systems are working properly.
5. The Material Safety Data Sheets should be followed to prevent adverse reactions
and injuries.
OTHER PRECAUTIONS
1. Access to the area of application should be limited to the workers applying the
product. In order to minimize exposure to unprotected individuals, measures
should be taken to prevent access to the area of application.
2. Because of the toxicity associated with the chemicals listed in this product,
measures should be taken to prevent contamination to groundwater or surface
water beyond the injection or remediation area.
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3. In order to minimize risk to the residents that may live near the application area,
measures should be taken to limit access to the area of application to workers
applying the product. In addition, measures should be taken to prevent the
product from being dispersed in the air or released on the ground outside the
application area.
Please do not hesitate to call me if you have any questions at [phone].
LW:pw
cc: Randy McElveen, NC Groundwater Section
Mr. Rick Raines, IR Program Director
Camp Lejeune, Commanding General PCS-EMD
Building 58, PSC Box 20004, Marine Corps Base
Camp Lejeune, NC 28542-004
Mr. Richard E. Bonelli
Michael Baker Jr., Inc., Airside Business Park,
100 Airside Drive
Moon Township, PA 15108
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INFORMATION NEEDED TO DO RISK ASSESSMENTS FOR
PRODUCTS APPLIED TO GROUNDWATER OR SOIL
CONTAINING NO MICROORGANISMS
SEND TWO COPIES TO:
UIC PROGRAM
GROUNDWATER SECTION
NORTH CAROLINA DENR-DWQ
1636 MAIL SERVICE CENTER
RALEIGH, NC 27699-1636
TELEPHONE [phone]
Note: Please provide direct responses to each of the following items, rather than "see
attachment", etc.
Required General Information
1. Department of Environment and Natural Resources Groundwater Section contact person
and phone number.
Response:
Mr. Randy McElveen
919-733-2801
2. Current or future use of site with site contact person, address, and phone number.
Response:
Current/future site use: Maintenance complex for amphibious vehicles, Camp Lejeune
Contact Person: Mr. Rick Raines, IR Program Director, Camp Lejeune, Commanding
General PCS-EMD, Building 58, PSC Box 20004, Marine Corps Base, Camp Lejeune, NC
28542-0004, [phone]
3. Contractor applying product, contact person, address, and phone number.
Response:
Contractor: Michael Baker Jr., Inc.
Contact Person: Mr. Richard E. Bonelli, Airside Business Park, 100 Airside Drive, Moon
Township, PA 15108, [phone]
4. Distance and likelihood of impact to public or private wells used for drinking, industrial
processes, cooling, agriculture, etc. Is area served by public water supply? Verification
must be provided by the appropriate Regional Offices of the Groundwater Section and
Public Water Supply Section.
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Response:
Distance to nearest Base water supply well: 2 active wells are roughly 1 mile from the site
Likelihood of impact: None, given the distance to the wells.
5. General description of the contaminants if present in the soil and/or groundwater at the
site.
Response:
Groundwater is impacted by various chlorinated compounds, including TCE, 1,2-cis-DCE,
1,2-trans-DCE, and vinyl chloride.
6. Name, approximate distance, and likelihood of impact to the nearest body of surface
water to the site.
Response:
Name: Courthouse Bay (part of the New River)
Distance: 500 feet
Likelihood of impact: None, due to the low groundwater velocity in the area to the bay.
7. Approximate distance to nearest residence(s) and workplace.
Distance: Site is within an active industrial compound on a military installation.
Required Product/Process-Specific Information
1. Product manufacturer name, address, phone number, and contact person.
Response:
Product names: Hydrogen (to be sparged as a substrate); helium (to be injected as a tracer)
Manufactures/supplier: National Welders Supply Company, Jacksonville, NC 910-353-
9291
2. Identity of specific ingredients (including CAS#) and concentrations of ingredients
contained in the product and purpose of each.
Response:
Ingredients:
Hydrogen: CAS #1333-74-0, 80% per volume, sparge gas
Helium: CAS # 7440-59-7, 20% per volume, tracer gas
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3. Approximate concentration of each ingredient following release into groundwater or soil.
Response:
Hydrogen: 0.5 mg/L (estimated)
Helium: 1 mg/L (estimated)
INFORMATION NEEDED TO DO RISK ASSESSMENTS FOR
PRODUCTS APPLIED TO GROUNDWATER OR SOIL
CONTAINING NO MICROORGANISMS
Page 2
Approximate distance and direction of travel for product in groundwater, the groundwater
concentration of each ingredient at this distance, and distance from this point to the
nearest drinking water source (that is currently used for drinking purposes). These should
be reasonably accurate estimates based on the best available information and calculations
(modeling, if necessary) regarding aquifer characteristics and flowpaths at the site; where
uncertainty exists in critical aquifer parameters (e.g. effective porosity), conservative
assumptions should be made in estimating these values so that worst -case predictions of
travel distances are made.
Response:
Based on the design prepared, the zone of influence will triangular, and extend up from the
injection well (depth of 70 feet below ground surface) a distance of approximately 40 feet
and extend outward 40 feet in each direction perpendicular to the injection. This equates
to a zone of influence of approximately 1,600 square feet.
5. Approximate groundwater concentration of each ingredient after pumping or recovery (if
applicable).
Response:
Not applicable
6. If the product is expected to discharge to a nearby surface water, approximate
concentrations of product in the water.
Response:
Not applicable. The product is not expected to discharge to any nearby waterways.
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7. Documentation from authoritative technical references of specific degradation products
expected.
Response:
No degradation products are anticipated with the products.
8. Documentation from authoritative technical references of expected migratory potential of
specific ingredients and degradation products in soil and groundwater.
Response:
The products are not anticipated to migrate or generate any degradation products that
would impact soil or groundwater.
9. Complete description of the use of the product at the site.
Response: (taken from the design specifications)
Hydrogen is now widely recognized as a key electron donor required for the biologically -mediated
dechlorination of chlorinated compounds. Hydrogen acts as an electron donor, and halogenated
compounds such as chlorinated solvents act as electron acceptors that are reduced in the reductive
dechlorination process. To enhance beneficial anaerobic processes for the purpose of
bioremediation, numerous research groups have focused on methods to increase the supply of
electron donor to the dechlorinating bacteria. Most researchers and technology developers have
focused on adding an indirect electron donor (such as lactate, molasses, mulch, edible oil, or other
carbon source) that is fermented by one type of bacteria to produce hydrogen for the
dechlorinators. Direct hydrogen addition simply eliminates the rate -limiting step (i.e.,
fermentation), by providing naturally -occurring dechlorinating bacteria with substantive quantities
of hydrogen, the key growth substrate (Hughes et al., 1997; Newell et al. 1998; Newell et al., 2000,
Newell et al., 2001).
Direct delivery methods that have been proposed include circulation of groundwater containing
dissolved hydrogen, placement of chemical agents that release dissolved hydrogen, electrolysis of
water with subsurface electrodes, use of colloidal gas aphrons (foams), and low -volume pulsed
biosparging (Hughes et al., 1997). Because of its simplicity and low-cost, AFCEE funded an 18-
month long field trial of low -volume pulsed biosparging of hydrogen gas in the subsurface. With
this approach, small volumes of hydrogen gas from cylinders were sparged directly into the
contaminated zone in short intervals. In this case the sparge interval was approximately one 20
minute pulse once a week for most of the test. Small volumes are used to ensure that breakthrough
to the surface will not present safety problems. The hydrogen is pulsed to allow effective dissolution
of the trapped gas, thereby transferring the residual hydrogen gas to the aqueous phase.
Results from an eighteen -month low -volume pulsed hydrogen biosparging pilot test at Cape
Canaveral Air Station Florida showed extensive biological dechlorination in a 30 x 30 ft (9.1 m x 9.1
m) zone located 15 to 20 ft (4.6 to 6 m) below the water table in a sandy aquifer. The test zone was
in or very near a DNAPL source zone, as chlorinated ethene concentrations were very high (-300
mg/L). Hydrogen gas was pulsed into three sparge points at regular intervals (weekly for most of
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the test) to form residual hydrogen gas bubbles, which then dissolved to deliver electron donor
directly to the test zone.
Significant concentration reductions were observed, both on a percentage basis and on an absolute
basis. Removals in wells close to the sparge point were more than 90%, and in downgradient wells
there was an approximately 50% reduction in contaminant concentration. More mass reduction
was also observed in the test zone than the two controls, although interpretation is difficult as some
of this removal may have been due to: 1) unintended hydrogen transport into the groundwater near
the control wells; and 2) natural changes in the plume.
DESIGN PARAMETERS
Based on previous hydrogen biosparging projects, the conceptual design of a hydrogen biosparging
system includes the determination of the following five key parameters: i) sparge volume, ii)
injection pressure, iii) gas flow rate, iv) sparge time, and v) sparge frequency. Additionally, a
method of measuring gas distribution and consumption (i.e. tracer gas injection) in the subsurface
should be selected and monitoring frequency determined.
Sparge Volume
Sparge volume refers to the volume of gas injected through the well and into the subsurface during
each sparging event. A conceptual model of the sparge volume resulting from hydrogen injection
into a horizontal well is illustrated in Figure 1.
Figure 1. Sparge Volume Conceptual Model
The sparge volume (V) is calculated via the following equation:
V(ft)=ZIxLxnxSg
where, ZI = zone of gas influence (ft)
L = length of screen (ft)
n = porosity (unitless)
Sg = gas saturation (unitless)
For the Camp Lejeune site, the length of screen, L, is 400 ft. and the porosity, n, is estimated as 0.3.
The other parameters, ZI and Sg, must be estimated based on experience and literature reports.
In previous vertical well injection systems, a zone of influence of approximately 10-15 ft in the
horizontal direction has typically been achieved (Newell et al. 2001). In a system similar to that
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proposed at Camp Lejeune, a horizontal well achieved methane delivery up to 100 ft. from the well
(USDOE 1995). As a conservative estimate, it is assumed that the zone of influence at Camp
Lejeune will be triangular (as depicted above in Figure 1), and extend up from the injection well a
distance of approximately 40 feet and extend outward 40 feet in each direction perpendicular to the
injection well. This equates to a zone of influence of approximately 1600 ft2.
The gas saturation is defined as the ratio of gas remaining in the system to total gas added. Gas
saturations achieved in the field are site -specific and variable depending on factors such as
subsurface heterogeneities, distance from sparge point, and formation of preferential flowpaths.
Previous studies have shown that hydrogen gas saturations are typically <0.5-2% up to 24 hours
following the sparge (GSI 2003). It is conservatively assumed that a gas saturation range of 0.5% to
1 % will be achieved at Camp Lejeune.
Since all parameters are known or have been estimated, the sparge volume for the Camp Lejeune
pilot test can be calculated. The result is a sparge volume in the range of approximately 1000
standard cubic feet (scf) to 2000 scf.
For this application, the volume of the well is significant and therefore should also be considered in
calculating the sparge volume. The proposed well has an open length of 900 feet and a 4-inch
diameter. This equates to a well volume of approximately 78.5 cubic feet. Adjusting the sparge
volume for the volume of the well, the new hydrogen volume required is about 1100 scf to 2100 scf.
Finally, the sparge volume must be corrected for the effect of hydrostatic pressure. Assuming a
water column of approximately 70 feet above the well, the hydrostatic pressure is about 2.1 atm.
The gas volume under this pressure is calculated using the following form of the Ideal Gas law:
PIVI = P2V2
where, PI = hydrostatic pressure (2.1 atm)
VI = volume of hydrogen required at 2.1 atm (1100 to 2100 scf)
P2 = atmospheric pressure (1 atm)
V2 = volume of hydrogen at 1 atm to achieve required volume at 2.1 atm
This relationship implies a given volume of gas at atmospheric pressure will be 2.1 times its volume
under hydrostatic pressure of 2.1 atm. Therefore, the resulting sparge volume required to achieve
delivery of 1100 scf to 2100 scf under the given hydrostatic pressure is calculated to range from
approximately 2300 scf to 4400 scf. Readily available cylinder packs contain approximately 2600
scf of hydrogen gas; therefore, the recommended sparge volume for the Camp Lejeune site is 2600
scf.
Injection Pressure
The pressure at which hydrogen is injected into the subsurface must be maintained above that
needed to induce gas flow into the subsurface (Pmin), and below the pressure resulting in fracturing
of the formation (l max)• These values are a function of the well depth and permeability of the
formation (Leeson et al. 2002).
Pmin is calculated as the sum of the hydrostatic pressure, the gas entry pressure for the well annulus
packing material, and the gas entry pressure for the formation. The gas entry pressure for the
packing material and the formation are typically less than 0.4 psig (for sands and silts), and are
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negligible compared to the hydrostatic pressure (Leeson et al. 2002). Therefore, the Pmin calculation
reduces to the following formula:
Pmin (psig) = 0.43 H
where, H = depth below water table of screen (ft), and the factor, 0.43, represents the hydrostatic
pressure in psig of 1 foot of water. From this equation, the minimum pressure required to induce
hydrogen flow, given the proposed well depth of 75 feet and groundwater occurrence of 5 feet (H =
70 feet), is calculated as 30.1 psig.
Injection pressure should remain below the overburden pressure, or Pmax, to avoid fracturing the
formation around the well. Overburden pressure is defined as the sum of the pressure of the soil
column and the pressure of the water column (USACE 1997). The pressure of the water column
was calculated above as Pmin. The pressure of the soil column, Psni,, is calculated via the following
equation (Sowers and Sowers 1970):
Psai1= Pb D
where, pb is the soil bulk density and D is the depth below ground surface of the screen. If a soil
bulk density of 105 lb/ft3 is assumed (NFESC 2001), then Pmax in units of psig can be calculated by
dividing the soil bulk density by 144 in2/ft2 to obtain a factor (0.73) for psig per foot of soil column.
Therefore, the formula for Pmax reduces as follows (USACE 1997; Battelle 1998):
Pmax = Psoil + Pwater
where, Pwater = Pmin, and substitute equation above for Psoil,
Pmax = Pb D + Pmin
then, substitute conversion factors discussed above to calculate Pmax in psig,
Pmax (psig) = 0.73 D + 0.43 H
The horizontal well is to be installed to a depth of approximately 75 ft below ground surface
resulting in a Pawl of 55 psig and a Pmax of approximately 85 psig (55 psig + 30.1 psig). The USACE
In -Situ Air Sparging Engineering and Design manual (1997) recommends the actual Pmax should be
between 60 and 80 percent of the calculated Pmax (i.e. safety factor of 20 to 40 percent). For the
Camp Lejeune sparging system, a safety factor of 30 percent is recommended, resulting in an actual
Pmax of 60 psig. Given the current knowledge of the Camp Lejeune site and the preliminary well
design (HWEC 2003), the estimated injection pressure for the hydrogen sparge system should be in
the approximate range of 31 psig to 60 psig.
Gas Flow Rate
Proper gas flow rate is important to ensure that gas distribution is maximized without generating
pressures that may lead to fracturing of the formation. There are few references of flow rates
specific to horizontal wells; however, typical ranges for flow rates used in vertical wells typically
range from <5 scfm to 40 scfm with typical screen intervals of 2 to 10 feet in length (USACE 1997,
NFESC 2001).
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In a successful demonstration of air sparging through a horizontal well, USDOE (1995) reported a
gas flow rate of 200 scfm air through a horizontal well installed at a total depth of 175 feet below
ground surface and 55 feet below the water table. The screen length for this well was 310 feet,
corresponding to 0.65 scfm per foot of horizontal well. This well achieved gas delivery up to 100
feet from the well based on electrical resistance tomography measurements. The flow rate used in
the USDOE study is consistent with a typical flow rate of 1 scfm per foot of horizontal well reported
by a horizontal well driller with air sparging experience (Wilson 2003).
The Camp Lejeune well has a proposed screen length of 400 feet. Using the normalized flow rate
referenced above (0.65 scfm per ft horizontal well), a gas flow rate of approximately 260 scfm air is
proposed for the Camp Lejeune hydrogen sparge system.
Since hydrogen is less dense than air, the equivalent hydrogen flow rate for 260 scfm of air must be
calculated. The relationship between gas flow rates and densities for two different gases is
expressed by the following equation (Felder and Rousseau 1986; Enardo 2003):
QH2
Q air
v pair _ y MWair
V PH2 V MWH,
where, Q = volumetric flow rate for respective gas
p = density of respective gas (air = 1.29 g/L; H2 = 0.09)
MW = molecular weight of respective gas (air = 29 g/mol; H2 = 2 g/mol)
From this relationship, the volumetric flow rate of hydrogen is 3.8 times greater than the equivalent
air flow rate. Therefore, a gas flow rate of 260 scfm air is equivalent to 1000 scfm hydrogen.
Sparge Time
The time required to deliver the desired volume of hydrogen with the flow rate proposed above is
simply calculated as the volume divided by the flow rate. Using the values proposed above (2600 scf
volume H2 / 1000 scfm flow rate), this corresponds to a sparge interval of approximately 2.6
minutes.
Sparge Frequency
Previous experience has shown that a sparge frequency of once per week is adequate initially (GSI
2003). However, as biomass throughout the system increases, hydrogen consumption also increases
and the frequency of sparging may need to be increased to compensate.
A determination of whether sparge frequency should be increased to twice per week will be made
based on data from a tracer gas study. The tracer gas study will be performed 6 months into the
pilot -test, and daily hydrogen and helium measurements following tracer gas injection will be used
to evaluate hydrogen consumption and lifetime.
TRACER GAS
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Helium is used as a tracer gas to determine the distribution and consumption of hydrogen gas.
Helium will be introduced into the hydrogen stream twice during the project at a final
concentration of 0.1%. The initial tracer gas study will be conducted after two weeks of operation
and the second study will be conducted after 6 months of operation.
For the tracer gas injection, one cylinder (of twelve) will contain a custom H2/He mixture at a He
concentration of 1.2% (remainder hydrogen). The remaining eleven cylinders will contain the
standard high purity hydrogen (99.995%). The gases will enter a manifold, where they will mix,
and the gas will enter the well at a H2/He concentration of 99.9%/0.1%. A sample port in the
delivery piping will allow the exact H2/He concentrations to be measured via a Summa® canister.
Immediately following tracer gas injection, the groundwater in all nearby wells is to be sampled for
hydrogen and helium via the bubble strip sampling method to determine hydrogen distribution.
The bubble strip sampler, manufactured by Microseeps, has a glass cell with an air bubble through
which groundwater flows until equilibrium is attained and hydrogen and He have partitioned to the
air bubble. A sample from the air bubble is then withdrawn and placed in an air -tight serum vial,
containing an internal standard, for analysis via a gas chromatograph equipped with an electron
capture detector by Consolidated Sciences (Houston, TX). Typical detection limits for hydrogen
and He are 1 ppm and 10-20 ppb, respectively.
Groundwater samples from approximately three wells in the vicinity of the injection well are
collected daily (for 4 to 5 days) following the tracer gas injection for hydrogen and He analysis to
determine hydrogen consumption rates.
Key Conceptual Design Parameters
Sparge Volume = 2300 to 4400 scf (estimate 2600)
Injection Pressure = 31 to 60 psig
Gas Flow Rate = 1000 scfm H2
Sparge Time = 2.6 minutes
Sparge Frequency = 1 per week
Tracer Gas = He (0.1%) injection at 2 weeks and 6 months
REFERENCES
Battelle, 1998. "Air Sparging for Site Remediation" Presentation, p. 58 of 97,
http://enviro.nfesc.navy.mil/erb/erb_a/restoration/technologies/remed/phys_chem/pres_air-
sparge.pdf
Enardo, 2003. Company website, "Vapor Flow to Equivalent Air Flow Conversion Equations",
http://www.enardo.com/Conversions.asp
Felder, R.M. and Rousseau, R.W., 1986. Elementary Principles of Chemical Processes, 2nd Edition,
John Wiley & Sons, Inc., New York.
GSI, 2003. "Low Volume Pulse Hydrogen Biosparging 2002 Annual Report", Groundwater
Services, Inc., Houston, TX.
Hughes, J., C. J. Newell, and R.T. Fisher, 1997. "Process for In -Situ Biodegradation of Chlorinated
Aliphatic Hydrocarbons By Subsurface Hydrogen Injection," U.S. Patent No. 5602296,
2/14/97.
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HWEC, 2003. "Horizontal Air Sparging Well Perforation Design" (Draft), Horizontal Well and
Environmental Consultants, LLC, Arvada, CO.
Leeson, A., Johnson, P.C., Johnson R.L., Vogel, C.M., Hinchee, R.E., Marley, M., Peargin, T.,
Bruce, C.L., Amerson, I.L., Coonfare, C.T., Gillespie, R.D., and McWhorter, D.B., 2002.
Air Sparging Design Paradigm, Battelle, Columbus, OH.
Newell, C.J., J.S. Hughes, R.T. Fisher, and P.E. Haas, 1998. "Subsurface Hydrogen Addition for
the In -Situ Bioremediation of Chlorinated Solvents," in Designing and Applying Treatment
Technologies, First International Conference on Remediation of Chlorinated and
Recalcitrant Compounds Conference, G. B. Wickramanayake and R. Hinchee, eds., May
21-28,1998, Battelle Press, Columbus, Ohio, pp. 47-52.
Newell, C.J., P.E. Haas, J. B. Hughes, and T.A. Khan, 2000. "Results From Two Direct Hydrogen
Delivery Field Tests For Enhanced Dechlorination," in Bioremediation and
Phytoremediation of Chlorinated and Recalcitrant Compounds, G. B. Wickramanayake, A.
R. Gavaskar, B.C. Alleman, and V.S. Magar, eds., The Second International Conference on
Remediation of Chlorinated and Recalcitrant Compounds Conference, Monterey,
California, May 22-25, 2000, Battelle Press, Columbus, Ohio, pg. 21-38.
Newell, C.J., C.E. Aziz, P.E. Haas, J. B. Hughes, and T.A. Khan, 2001. Two Novel Methods for
Enhancing Source Zone Bioremediation: Direct Hydrogen Addition and Electron Acceptor
Diversion, Anaerobic Degradation of Chlorinated Solvents, pg. 19-26, In: Anaerobic
Degradation of Chlorinated Solvents, V. Magar, D. Fennell, J. Morse, B. Alleman, and A.
Leason, eds., In Situ and On -Site Bioremediation: The Sixth International Symposium,
Battelle Press, Columbus, Ohio.
Sowers, G.B., and Sowers, G.F., 1970. Introductory Soil Mechanics and Foundations, 3rd Edition,
Macmillan Publishing Co., Inc., New York.
NFESC, 2001. Air Sparging Guidance Document, Technical Report TR-2193-ENV, Naval Facilities
Engineering Service Center, Port Hueneme, CA.
USACE, 1997. In -Situ Air Sparging Engineering and Design Manual, EM1110-1-4005, US Army
Corps of Engineers, Hyattsville, MD.
USDOE, 1995. In Situ Bioremediation Using Horizontal Wells, Innovative Technology Summary
Report, US Department of Energy Office of Environmental Management Office of
Technology Development.
Wilson, David, 2003. Personal communication, July, 11, 2003.
The risk assessment will be forwarded to the designated contact person for the site, consultant
applying the product, and Groundwater Section contact person.
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