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Innovative
Methods to Identify, Map and Plot Historic Areas of
Environmental Concern for the Purpose of Developing
Accurate Sampling Plans
Neil
Jiorle, Schoor DePalmer, Manalapan, NJ
Alternatives
to NAPL Thickness Measurements for NAPL Characterization
Stephen
S. Boynton, Ambient Engineering, Inc., Concord, MA
Gerry Garibay, El Paso Corporation, Houston, TX
Natural
Attenuation of a Co-contaminated Solvent-Metal Plume
Ronnie
Britto, Ensafe Inc, Memphis, TN
Allison
Harris, Ensafe
Inc, Memphis, TN
William
Hill, Southern Division Naval Facilities Engineering
Command, North Charleston, SC
Downward
Migration of LNAPL at the Hadnot Point Industrial Area,
Marine Corps Base, Camp Lejeune, North Carolina
Lori
Parks Reuther, Naval Facilities Engineering Command,
Norfolk, VA
James A. Dunn, The IT Group, Alpharetta, GA
Natural
Attenuation Rate Clarifications: The Devil's in the
Details
Joseph E. Odencrantz, Tri-S Environmental Consultants,
Costa Mesa, CA
Mark
D. Varljen, SCS ENGINEERS, Bellevue, WA
Richard A. Vogl, R.G., CHG, HydroGeo Consultants, Costa
Mesa, CA
Innovative
Methods to Identify, Map and Plot Historic Areas of
Environmental Concern for the Purpose of Developing
Accurate Sampling Plans
Neil
Jiorle,
Vice President, Schoor DePalma, 200 State Highway Nine,
Manalapan, NJ 07726-0900, Tel: 732-577-9000 extension
1017, Fax: 732-577-8168, Email: njiorle@schoordepalma.com
Various
methods have traditionally been used by environmental
regulators and consultants to identify and locate historic
areas of environmental concern (AOCs).
These methods have included reviews of: historic
aerial photographs, Sanborn and other fire insurance maps,
industrial directories, title and deed records, tax maps,
and facility records among other sources. On site geophysical surveys using equipment such as ground
penetrating radar (GPR) have also been used.
Recent developments in the fields of geographic
information systems (GIS) using digital satellite imagery,
autocad, and global positioning system (GPS) location
mapping using satellite uplinks, when used together and in
combination with the traditional methods, have made it
possible to identify and located historic AOCs with
sub-meter accuracy.
By
combining and applying these methods, sampling plans can
be developed that allow for the accurate investigation of
potential contamination emanating from these AOCs even
though there is currently no physical, surface grade
evidence of their former locations.
In the
project discussed in this paper, historic topographic maps
and site plans were available and were analyzed to
ascertain the exact location of each AOC with respect to
fixed referenced points that were present historically and
that currently exist.
The AOC locations were identified in the field by a
New Jersey licensed land surveyor who, using state of the
art GPS equipment, navigated to, and provided coordinates
for, each AOC location using the fixed reference points.
The AOC coordinates were down loaded into an
Autocad system that plotted coordinates and elevations on
a current topographic site plan.
Accordingly, each sample location proposed in the
Site Investigation Work Plan (SIWP) was identified by
northing, easting, and elevation coordinates.
Alternatives
to NAPL Thickness Measurements for NAPL Characterization
Stephen
S. Boynton,
P.E., Ambient Engineering, Inc., 100 Main Street, Suite
330, Concord, MA 01818, Tel: 978/369-8188, Fax:
978/369-8380
Gerry
Garibay, El Paso Corporation, 1001 Louisiana Street,
Houston, Texas 77002
NAPL
thickness measurements in monitoring wells are often used
to characterize the extent of NAPL releases.
Measured product thickness is frequently used to
estimate the thickness of a “floating” NAPL layer.
The presence of more than ˝-inch of NAPL in a
monitoring well triggers a reporting condition in
Massachusetts. Additionally,
Massachusetts has a minimum cleanup standard (Upper
Concentration Limit) of ˝-inch of NAPL “in the soil
column”. However,
the real meaning and value of NAPL thickness measurements
is unclear.
Long-term
product thickness measurements were available for a
release at a fuel storage terminal near Boston, MA.
Maximum product thickness measurements in one area
of the site exceeded six-inches.
However, on many occasions no NAPL was detected in
the any of the monitoring wells within the plume; i.e. a
“false negative” condition.
In-situ
oxidation was chosen as the remedial option for the NAPL. A reliable estimate of the quantity of NAPL in the plume was
needed to evaluate the quantity of hydrogen peroxide
needed for the remediation.
NAPL thickness measurements were deemed
insufficient to allow an estimate of the NAPL volume.
Additional characterization was performed to
determine the vertical and horizontal extent of
contamination, and to estimate the mass of NAPL in the
plume.
Continuous
soil sampling was performed through the NAPL “smear
zone”. Field screening was used to select samples for analysis.
All samples in the smear zone were analyzed for
total petroleum hydrocarbons.
A calculation of the total mass per unit area at
each soil boring was performed using the TPH data and
assumed values of porosity and specific gravity of solids.
Total mass within the plume was then calculated by
contouring the mass per unit area data.
Mass per unit area data was converted to an
“equivalent product thickness” for comparison to the
measured product thickness data.
Natural
Attenuation of a Co-contaminated Solvent-Metal Plume
Ronnie
Britto, EnSafe Inc., 5724 Summer Trees Drive, Memphis,
TN 38134, Tel: 901-372-7962, Fax:
901-372-2454,
Allison Harris,
EnSafe Inc., 5724 Summer Trees Drive, Memphis, TN 38134,
Tel: 901-372-7962
, Fax:
901-372-2454
William J. Hill,
Southern Division Naval Facilities Engineering Command,
2155 Eagle Drive
, North
Charleston, SC 29419-9010, Tel: 843-820-7324, Fax: 843-820-7465
A natural
attenuation evaluation was performed for two groundwater
plumes at the Naval Air Station (NAS) in Pensacola,
Florida. The primary constituents of concern (COCs) are
tetrachloroethylene (PCE), trichloroethylene (TCE), and
heavy metals. Groundwater
samples were collected and analyzed for MNA (monitored
natural attenuation parameters) and COCs in December 1998,
May 1999, and December 2000.
Chemical and geochemical data were evaluated to
determine the site’s MNA potential.
Dissolved Oxygen (DO) and redox potential (ORP)
indicated anaerobic conditions within the two plumes.
Wells upgradient of the two plumes had DO greater
than 1.0 mg/L. Methane
and sulfide were measured at concentrations well over
1,000 µg/L in several wells.
Hydrogen concentrations in these wells also
indicated that sulfate-reducing and methanogenic
conditions prevailed in the plumes.
Chemical data collected since 1994 show that parent
compounds such as PCE and TCE have decreased over time.
At some locations, the decrease is greater than
ninety percent. Data
also shows a decrease in groundwater flow direction with
wells in downgradient locations being below the MCL for
these compounds. Daughter
products cis-1,2-DCE and vinyl chloride have been detected
in plume wells but are not accumulating in the direction
of groundwater flow.
Favorable geochemical conditions also appear to be
have positively impacted lead and cadmium concentrations
in groundwater. Concentrations
of these metals have decreased dramatically since sampling
first began in 1994 when they were greater than 300 µg/L.
In the December 2000 sampling event, most area
wells were non-detect for cadmium and lead.
It appears that anaerobic conditions, the presence
of sulfate, and the formation of sulfide are helping to
precipitate these metals as stable sulfides, thereby
immobilizing them in the aquifer.
Based on the overwhelming evidence for the natural
attenuation of chlorinated solvents and metals in the
aquifer, MNA was recommended and has been accepted as the
site remedy.
Downward
Migration of LNAPL
at the Hadnot Point Industrial Area, Marine
Corps Base, Camp Lejeune, North Carolina
Lori
Parks Reuther,
Atlantic Division, Naval Facilities Engineering Command,
Environmental Division, Code EV21LR, Lafayette River Annex
- Building A, 6500 Hampton Blvd., Norfolk, VA 23508, Tel:
757-322-4779, Email:
reutherlp@efdlant.navfac.navy.mil
James A. Dunn, Jr.,
P.E., The IT Group,
address: 11560
Great Oaks Way, Suite 500, Alpharetta, GA, Tel:
770-663-1433, Email:
jdunn@theitgroup.com
More than
a decade of study at the Hadnot Point former Fuel Farm
located on the Marine Corps Base, Camp Lejeune,
Jacksonville, NC had yielded what first appeared to be a
contaminated project site typical of older fuel farms.
Standard investigatory procedures such as
installation of approximately one hundred monitoring
wells, numerous direct pushes, gauging and sampling were
implemented to aid in the delineation of existing free
phase and dissolved phase product plumes over a period
spanning twenty five years.
Resultant data was compiled and used to create an
interpreted aerial extent of the plume boundaries that
existed at the site.
It is estimated that as much as 1,100,000 gallons
of gasoline may have been released over a fifty year time
span from 1941 to 1991.
A multi
faceted remediation system which included air sparging,
soil vapor extraction, biosparging, and free product
recovery was designed and installed in 1997 to address the
soil and groundwater contaminated plumes and is currently
in operation today. These
systems constructed at a cost of just over one million
dollars, have been successful in removing in excess of
250,000 gallons of fuel in both free and volatile phase.
However,
the occurrence of anomalous conditions such as free
product presence in a double cased well 153 feet deep,
sample results in at least six well pairs exhibiting
dissolved benzene levels significantly higher in 50 feet
deep double cased wells than their neighboring shallow
wells at a depth of between fourteen and twenty five feet
deep, and recurrence of unweathered free product in a
shallow well after free product absence for ten years,
resulted in the necessity of examining the root cause of
these contaminant deviations at the project site.
Though it
is not normally accepted that an LNAPL could vertically
migrate downward below the saturated zone and subsequently
reside in the deeper subsurface regions, a combination of
multiple hurricanes occurring in a short period of time
and aggressive pumping during drought conditions
contribute to the complex subsurface conditions necessary
for this phenomenon to occur.
This presentation details the subsurface and
environmental circumstances present at the site along with
the advanced geophysical investigations conducted which
explain the mechanisms at work allowing for the vertical
downward migration of an LNAPL at the Hadnot Point
Industrial Area.
Natural
Attenuation Rate Clarifications: The Devil’s in the
Details
Joseph
E. Odencrantz,
Tri-S Environmental, 3151 Airway Avenue, Bldg. H1, Costa
Mesa, CA 92626, Tel: 714-966-8490, Fax: 714-966-5222
Mark
D. Varljen,
SCS Engineers, 2405 140th Avenue, NE, #107,
Bellevue, WA 98005
, Tel:
425-746-4600, Fax: 425-746-6747
Richard
A. Vogl,
R.G., CHG, HydroGeo Consultants, 3151 Airway Avenue, Bldg.
H1, Costa Mesa, CA 92626, Tel: 714-966-5333, Fax:
714-966-5222
The term
"Natural Attenuation" (NA) has been defined as
naturally-occurring processes in soil and groundwater
environments that act without human intervention to reduce
the mass, toxicity, mobility, volume, or concentration of
contaminants in those media. Monitored natural attenuation
(MNA) protocols generally involve the collection of
biogeochemical data from groundwater monitoring wells at
sites. The data are correlated in time and space with the
various chemicals of concern (COC’s) to establish
predominant biodegradation mechanisms. Modelers
using the first-order decay expression typically use the
rate coefficient as a calibration parameter and adjust it
until the transport model results match field data.
With this approach, uncertainties with a number of
parameters (e.g., dispersion, sorption, biodegradation,
etc.) are lumped together in a single calibration
parameter. We examine the problems associated with the
lumped parameter approach using two commonly used models,
BIOSCREEN and Buscheck/Alcantar Analytical Solution
in a variety of practical examples. The natural
attenuation decay rate estimated using the lumped
parameter approach is distinguished from a biodegradation
rate established by isolating processes and examining
biodegradation lines of evidence. The half-life determined
from empirical data using the lumped parameter approach is
often mistakenly interchanged with a biodegradation
half-life when it is an all encompassing half-life based
on the interaction of numerous processes. We isolate the
processes as they are represented in the governing
transport equation and provide a rationale approach at
parameter estimation to avoid the potential pitfalls of
the all-inclusive “attenuation rate”. In
closing, general guidelines on degradation rates and
half-lives are broken into four categories-process
clarification, specifics on enumeration, isolation of
other processes and biodegradation lines of evidence.
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