David Bausmith, Author

1. W
hen commercial properties in prime locations are left vacant due
to environmental impacts to the soil and groundwater caused by
past industrial practices, there is significant incentive to return
these Brownfield sites to usefulness. One such site is located in Port Newark,
N.J., which is one of the largest shipping ports in the New York/New Jersey
area. The site was previously operated as a wood treating facility from 1940
until operations ceased in 1991, and remained vacant until remediation
commenced under the jurisdiction of the New Jersey Department of
Environmental Protection (NJDEP).
Cement-based solidification/stabilization was used to address arsenic-
and creosote-impacted soils at the site. Prior investigations at the site found
free phase creosote in deep soils (0-12 feet), and arsenic-impacted surface
soils (0-2 feet). Remediation of the site involved the in-situ
solidification/stabilization of “deep” creosote-impacted soils, ex-situ solidi-
fication/stabilization of arsenic-impacted soils, and use of the treated soils as
sub-grade materials for construction of an asphalt surface cover system
designed for use as a container storage facility.
Approximately 25,000 cubic yards of material was treated in-situ using an
excavator-mounted mixing tool, and approximately 27,000 cubic yards of
material was excavated, treated through a pug mill, and re-used at the site as
soil-cement base for the asphaltic concrete pavement.
The use of soil-cement as an asphalt base course material reduced con-
struction costs by obviating the need to import additional fill. As a result of
the treatment, creosote and arsenic in the soil were successfully immobilized
and contained at the site and the Port Authority of New York and New Jersey
returned the property to productive use.
Background
The site consists of approximately eight acres of property, located between
the Elizabeth and Port Newark shipping channels, in Port Newark. The site
is owned by the City of Newark and is leased to the Port Authority of N.Y.
and New Jersey (Port Authority). The site was formerly operated as a wood-
treating facility (under various lessors) from 1940 until operations were
ceased in May 1991. Since razing of the former wood treating facilities in
1991, the property remained vacant.
The wood treating process utilized preservatives including creosote and
chromated copper arsenate (CCA). The creosote and CCA were stored on-
site in above-ground storage tanks, and pumped via underground pipelines
to above-ground treatment cylinders. Wood poles were moved into the
treatment cylinders via rail cars, and subsequently treated under pressure
with preservative chemicals. Following treatment, the cylinders were de-
pressurized and opened (at which point excess preservative was drained
from the cylinder and collected in sumps located beneath the door of the
cylinder), and the rail cars were wheeled out of the cylinder to an unpaved
drip track area, where excess preservative dripped from the poles to the
track. The treated poles were removed from the rail cars and transferred to
outdoor lumber storage areas. As a result of these historical wood-treating
operations, soil and groundwater at the site was impacted with constituents
Cementing
DNAPLsBy David S. Bausmith

2. Cementing
DNAPLs
related to the wood-treating chemicals.
Numerous on-site environmental
investigations were performed between
1984 and 1998, which identified contami-
nants related to the former wood-treating
operations in both surface and subsurface
soils on-site. Arsenic was generally present
in the top two feet of soil across the entire
site. Creosote, in the form of Dense Non-
Aqueous Phase Liquid (DNAPL), was
present over approximately two acres of
the site at depths up to approximately 12
feet beneath ground surface. The arsenic
and DNAPL represented a potential
source material for on-going groundwater
impacts. The NJDEP required these
“sources” be removed, if practicable, or
treated. A total of approximately 50,000
cubic yards (cy) of arsenic and/or
DNAPL-impacted material existed in
shallow and deep soil at the site.
Remedial action/redevelopment
requirements
A Remedial Action Work Plan (RAWP)
for the site was approved by the NJDEP
in July, 1999, which outlined the
Remedial Action Objectives (RAOs) for
the site and methods for achieving those
objectives. The RAO included: 1) reduc-
ing the potential for direct contact expo-
sure to constituents in surface soils; 2)
restricting future on-site groundwater
use, and mitigating potential migration
of constituents to potential off-site
receptors and deeper groundwater; and,
3) reducing the potential mobility of
DNAPLs and minimizing future dissolu-
tion of DNAPL constituents and arsenic
to the groundwater. During development
of the RAWP, numerous remedial alter-
natives were considered which would sat-
isfy these RAOs (i.e., potential source
material removal, slurry wall contain-
ment, pumping and treatment of
groundwater, etc.). However, many alter-
natives were either not practicable or
extremely costly. Additionally, because
the Port Authority ultimately desired to
return the site to productive use as a
marine cargo storage facility, the remedi-
al actions selected for the site had to be
consistent with the proposed end use.
Improvements to the site’s infrastruc-
ture were also required to render the
property functional as a marine cargo
storage facility. Specifically, the site
required construction of new storm
water drainage, electrical supply, and
potable water supply systems, as well as
an asphaltic concrete pavement cover.
Although required for redevelopment,
the asphaltic concrete pavement would
also satisfy the remedial requirement to
prevent direct contact exposure to con-
stituents in the surface soil. In order for
the storm water drainage system to func-
tion properly, the entire surface of the
site had to be raised by approximately
two feet above existing grades. The final
site surface also had to be constructed in
accordance with strict grade tolerances
and strength requirements stipulated by
the Port Authority. For example, the final
surface could not exhibit grade transi-
tions exceeding 0.5 percent over a dis-
tance of 20 feet to minimize the potential
for stacked cargo containers to tip. The
final surface also had to withstand 100
repetitious H-20 rated loadings per day,
which represented the anticipated traffic
conditions for the site.
Cement-based
solidification/stabilization
In order to achieve the RAOs for the site
and simultaneously provide a site that met
the Port Authority’s requirements for stor-
age of marine cargo, cement-based solidi-
fication/stabilization (S/S) was selected as
the primary remedial action. The NJDEP
approved this approach, based on the
results of treatability studies which showed
that contaminants in the soil would be
effectively immobilized after being blend-
ed with eight percent Type I Portland
cement by wet weight of soil.As part of the
remedial design phase, minimum strength
requirements were established for the shal-
low and deep stabilized soils. Deep stabi-
lized soils were required to provide a min-
imum 28-day unconfined compressive
strength (UCS) of 25 pounds per square
inch (psi), and shallow stabilized soils were
required to provide a minimum seven-day
UCS of 250 psi.
Cement-based S/S of target site soils
was accomplished using a combination of
in-situ and ex-situ technologies.
Treatment of deeper soils impacted with
DNAPL was completed in-situ to elimi-
nate need to remove, handle and treat
materials above-grade. In addition, in-situ
treatment minimized the release of
volatile constituents during treatment
that could otherwise require costly
vapor/odor control equipment if DNAPL-
impacted soils were removed and treated
above-grade.
Shallow soils were treated ex-situ in a
pug mill. Soils treated in the pug mill not
only provided a material that could be
graded to achieve final design topography
for the site, but also provided a high-
strength base for the asphaltic concrete
pavement which would withstand the
anticipated traffic loads for the site.
In-situ S/S of the deeper soils was
accomplished using proprietary equip-
ment provided by the Lang Tool
Company, consisting of a hydraulically-
powered mixing head mounted on an
excavator. A mobile on-site slurry plant
was used to prepare cement-water slurry,
which was pumped directly to the in-situ
mixer via flexible hoses. Flow metering
equipment was used to control the quan-
tity of cement blended with the soil, and
to ensure that a minimum of eight percent
cement by wet weight of soil was added.
Approximately 25,000 cy of deep soil
were treated in-situ for the project, at an
average rate of 450 cy per day. The average
volumetric increase of the deep soils fol-
lowing treatment and curing was 23 per-
cent. This bulking effect reduced the
quantity of imported fill required to
achieve final design grades by approxi-
mately 5,800 cy. Laboratory testing of
samples of the treated deep soil indicated
that the cured material consistently
achieved the minimum 28-day uncon-
fined compressive strength requirement of
25 psi. Adequate strength was generally
achieved within seven-days, with the
seven-day UCS averaging 95 psi.
Confirmatory test pits completed in the
treated deep soils verified that S/S activi-
ties homogeneously mixed the soil and
cement, and effectively immobilized
DNAPL in the deeper soils.
Ex-situ S/S of shallow soils was accom-
plished by systematically stripping the top
two feet of soil from the site, screening the
soil to remove debris larger than three

3. inches in diameter, crushing the oversized material down to a maximum
dimension of 1.5 inches, mixing the screened soil and re-sized material with
eight percent cement by wet weight of soil and placing and compacting the
stabilized material on-site. The pug mill was equipped with spray bars to add
water (as needed) to the soil and cement during mixing to maintain the
moisture content of the soil-cement at, or slightly above, the material’s opti-
mum moisture content for compaction. The treated shallow soils were spread
in lifts between six and eight inches in thickness, and compacted to a mini-
mum of 95 percent of Modified Proctor maximum dry density.
A total of approximately 27,000 cy of shallow soil were treated during the
project, and treatment rates ranged from 200 to 700 cy per day. The seven-
day UCS of the soil-cement samples tested during construction consistently
exceeded the minimum requirement of 250 psi, and averaged a value of 600
psi. Because the soil-cement served as the base course for the asphaltic con-
crete pavement system, the unexpectedly high UCS of the soil-cement sug-
gests that the loading capacity and/or service-life of the pavement will be
greater than anticipated as part of the design.
Cement-based S/S activities at the site were completed between
December, 2000 and April, 2001. The storm water drainage, water supply
and electrical lighting systems were constructed concurrently with the S/S
activities. Construction of the asphaltic concrete pavement cover was com-
pleted in November, 2001, and the Port Authority returned the site to active
use in March, 2002.
Summary
Cement-based S/S was effectively implemented for the remediation and
redevelopment of a former wood-treating site in Port Newark, N.J.
Approximately 52,000 cy of soil impacted with wood treating chemicals
were treated via in-situ and ex-situ S/S technologies with eight percent Type
I Portland cement by wet weight of soil. The S/S treatment effectively immo-
bilized the soil and the related contaminants on-site, precluding the need to
remove and dispose of soils off-site. The volumetric increase of site soils
resulting from the S/S activities also reduced construction costs by offsetting
imported fill requirements. Further cost savings related to potential import-
ed fill requirements were realized through the effective use of soil-cement as
sub base material for the asphalt pavement. Treatment of the soils via
cement-based S/S also resulted in dramatic improvements in the bearing
strength of the site, which has rendered the property suitable for use as a
marine cargo storage facility.
The post-remediation monitoring requirements include quarterly
groundwater flow monitoring and sampling/analysis. This will continue for
a minimum of eight quarters (started the first quarter of 2002). In its early
stages, the post remediation groundwater monitoring indicates site-related
contaminants are being contained. More significantly, test pits and visual
inspections performed after implementing the stabilization remedy con-
firmed that the source material was immobilized. PE
For more information contact, David S. Bausmith, P.E., Key Environmental
Inc., 456 Route 22 West, Suite D, Whitehouse Station, N.J., 08889.
Approximately 25,000 cy of deep soil were
treated in-situ for the project, at an average
rate of 450 cy per day.

4. Reprinted from Pollution Engineering, Copyright November 2002.