PB95-963132
EPA/ESD/R10-94/104
March 1995
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Bangor Naval Submarine Base,
Site F, Bangor, WA
7/18/1994
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EXPLANATION OF SIGNIFICANT DIFFERENCES (ESD)
FOR THE INTERIM REMEDIAL ACTION
SITEF
SUBASE, BANGOR
BANGOR, WASHINGTON
Introduction
Site F at the Naval Submarine Base, Bangor (SUBASE, Bangor) is located
in the south-central portion of the SUBASE. SUBASE, Bangor is located
on Hood Canal in Kitsap County, Washington, approximately 10 miles
north of Bremerton. The lead agency for this National Priorities List
(NPL) site is the U.S. Navy. The U.S. Environmental Protection Agency
(EPA) and the Washington State Department of Ecology (Ecology) have
provided support and oversight on the preliminary studies, site
investigations, remedial alternative selection, and design and construction
of the Interim Remedial Action (IRA) at Site F.
This ESD is prepared in accordance with Section 117(c) of the
Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) and Section 300.435(c)(2)(i) of the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP). It addresses the change
from ultraviolet/oxidation (UV/Ox) technology to granular activated carbon
(GAC) technology for treatment of groundwater extracted under the Site F
IRA. A reevaluation of these alternative technologies concluded that GAC
treatment of the extracted groundwater is equally implementable, equally
effective, and substantially less expensive than UV/Ox treatment.
Public notice of this ESD will be published in a major local newspaper.
The ESD will be available for review in the information repositories
located at the following Kitsap regional libraries:
Central Kitsap Library (206) 377-7601
1301 Sylvan Way
Bremerton, Washington 98310
Bangor Branch (206) 779-9724
Naval Submarine Base, Bangor
Silverdale, Washington 98315-5000
The ESD will also become part of the Administrative Record File in
accordance with NCP 300.825(a)(2). The Administrative Record for Site
F is available between the hours of 0800 and 1600 at:
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Engineering Field Activity, Northwest
Naval Facilities Engineering Command
1040 Hostmark Street
Poulsbo, WA 98370
(206) 396-5984
Summary of Site History, Contamination Problems, and Selected IRA
The Bangor Naval complex served as a munitions handling, storage, and
processing site from the early 1940s until 1971. Site F, which consists of
a former unlined lagoon and overflow ditch, was used between
approximately 1960 and 1971 for the disposal of wastewater produced
during the demilitarization of ordnance items in an adjacent Segregation
Facility. Demil activities conducted in the Segregation Facility included
initial separation of solid ordnance from the projectile casings, followed by
steam cleaning of the casings. Condensate and ordnance residual from this
process were collected in a holding tank. Holding tank effluent was treated
in skimming and settling chambers to remove solids prior to discharge to
the lagoon.
The wastewater discharged to the unlined lagoon contained relatively high
residual concentrations of trinitrotoluene (TNT) and hexahydro-1,3,5-
trinitro-l,3,5-triazine (RDX), and lower concentrations of other ordnance
compounds. Much of the wastewater apparently infiltrated through the
bottom of the lagoon. During periods of heavy discharge, however,
wastewater overflowed the lagoon into a narrow depression (ditch) to the
south. Periodically, the lagoon was allowed to drain, and waste materials
at the surface of the lagoon were "burned off" in place or transported off
site for burning and disposal.
No records were kept on the quantity of wastewater disposed of to the
lagoon. In 1972-73, the lagoon was taken out of service, and process
wastewater was subsequently collected in drums and delivered to the
SUBASE, Bangor liquid-waste incinerator. The rate of wastewater
delivery to the incinerator was estimated at 240 gallons per day.
In 1980, demil operations were terminated and the former lagoon area was
filled in and covered with asphalt. The Segregation Buildings were
subsequently decontaminated and converted to storage.
In 1978, evaluation of SUBASE, Bangor waste disposal sites (including
Site F) began under the Navy Assessment and Control of Installation
Pollutants (NACIP) program. Work at Site F continued in 1981 as part of
an Initial Assessment Study (IAS) and in 1986 as part of a Characterization
Study, both under the NACIP program. With the enactment of the
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Superfund Amendments and Reauthorization Act (SARA) in 1986, the
Navy suspended further NACIP program activities and phaSed into the
EP A Remedial Investigation/Feasibility Study (RIlFS) program. In August
1990, SUBASE, Bangor (including Site F) was officially listed on the
National Priorities List (NPL) of Hazardous Waste Sites. The RIIFS
investigation fQr the final remedial action at Site F is ~urrently ongoing.
The disposal of ordnance wastewater at Site F resulted in contamination of
soil and groundwater. Roughly 75 percent of the estimated total mass of
ordnance at Site F is present within unsaturated soils beneath the fonner
wastewater lagoon and overflow ditch. The remaining 25 percent is
present in the Shallow Aquifer, an unconfined aquifer located at a depth of
approximately 50 feet beneath the site. Water quality data indicate that.
RDX has been transported in the Shallow Aquifer up to approximately
3,000 feet downgradient (west-northwest) of the fonner lagoon. Other
ordnance compounds, such as lNT and DNT, have migrated less than
1,500 feet downgradient, and remain well within the extent of elevated
RDX concentrations in the aquifer.
The Record of Decision (ROD) for the Site F IRA was signed in .
September 1991. It addresses the threat posed by the site by providing
. groundwater containment and on-site treatment with penn anent reduction in
the mobility, toxicity, and volume of contamination. The elements of the
Site F IRA as set forth in the ROD. include:
~ Extraction of groundwater from the Shallow Aquifer to contain the
contamination and thereby confine further contaminant movement in the
aquifer; .
~ Treatment of the extracted groundwater using UV lOx technologies to
meet applicable regulations prior to disposal; .
~ Disposal of the treated groundwater on base by recharge or injection
into the Shallow Aquifer; and
~ Monitoring the effectiveness of the groundwater containment and
groundwater treatment processes. .
Description of the SignifICant Differences and the Basis for Those Differences
UV lOx and GAC were evaluated in the ROD for the Site F IRA as.
alternative technologies for treatment of extracted groundwater. It was
determined that both technologies were capable of meeting the threshold
criteria (protective of human health and the environment, and compliance
with ARARs). The estimates prepared at that time al~o showed
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comparable costs for these technologies. UV lOx was selected for the
following reasons:
.. UV/Ox was considered to be more "implementable". due to limited
availability of facilities capable of regenerating or disposing of spent
GAC;
.. UV lOx provides on-site destruction of contaminants; and
.. UV lOx is an innovative technology.
Based on current infonnation, the implementability of GAC is no longer a
problem. The carbon manufacturerlsupplier selected by the Navy's
Remedial Action Contractor (RAC) is now capable and willing to accept
ordnance-laden GAC at their carbon regeneration facility. Their previous
reluctance to handle the spent GAC, which was based on carbon
regenerability considerations, can now be effectively addressed by limiting
ordnance loading on the GAC. Accordingly, GAC is now considered
equally as implementable as UV lOx technology. Since adsorbed ordnance
compounds are thennally destroyed in the regeneration process, this
treatment technology also satisfies the statutory preference for penn anent
treatment to reduce toxicity, mobility, and vglume. .
Table 1 presents current cost estimates for the Site F IRA using UV lOx
versus GAC for groundwater treatment. Treatment by UV lOx is estimated
to cost $800,000 more than treatment by GAC, based on two years of IRA
operation. This is primarily due to the large difference in treatment"
technology capital costs. A treatment plant. using either technology would
require many common items, such as process pumps, holding tanks, filters
for suspended solids removal, and interconnecting piping. The only.
significant "unique" equipment required for GAC treatment are process
vessels to hold the activated carbon itself. "The GAC cost estimate assumes
that a Calgon Model 10 Dual Adsorption Unit is purchased for this purpose
at a cost of approximately $190,000. "
Equipment requirements and costs for UV lOx treatment are based on the
findings of the UV lOx Treatability Study perfonned for Site F. In addition
to the UV/Ox reactor itself, UV/Ox treatment w01Jld require facilities for
. ozone generation, acid and base storagelinjection (for water pH .
adjustment), gas recompressionlrecycling, and destruction of residual ozone
in the offgas. The capital cost of equipment unique to UV lOx treatment is
estimated at $800,000. The equipment cost differential between treatment
technologies is therefore estimated at $610,000. Applying a contingency
factor of 15 percent (to account for unforeseen additional costs) results in
the capital cost differential of $700,000 as shown in rable 1.
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The corresponding cost estimates provided in the Site F IRA ROD are also
shown in Table I for comparison. Estimates of total costs for both
technologies have dropped since the ROD evaluation. This is due to the
much lower costs now estimated for system operation and maintenance
(O&M) in both cases. Lower O&M costs partly result from the lower
ordnance concentrations, that are now anticipated in the extracted
groundwater. This concentration reduction has a greater impact on GAC
O&M costs, since they are more concentration-dependent than are UV lOx
O&M costs.
Another reason why GAC O&M costs have declined is that, as noted
above, spent carbon can now be regenerated for reuse. The UV lOx
Treatability Study, on the other hand, demonstrated that substantial
reductions in UV lOx O&M costs were also justified. The net result based
on these analyses and present technology, however, is that GAC is now
estimated to be significantly less expensive than UV lOx from both a capital
and an O&M cost perspective.
GAC treatment still requires off-site tra.I:1sport of contaminants prior to their
ultimate destruction. However, current estimates indicate that, for a 225
gpm treatment rate, only about two 20,OOO-pound truckloads of spent
carbon per year will require transport to a regeneration facility.
The distinction of UV/Ox as an innovative technology still applies as well.
However, the greater cost-effectiveness of GAC treatment outweighs the
UV lOx advantages of on-site contaminant destruction and innovative
technology.
Based on the data now available, GAC is proposed for use in place of
UV lOx to treat extracted groundwater under the Site F IRA. Regulations
which apply to transporting GAC to and from Site F will be included as
ARARs for the remedial action. Transport of this material will be
conducted in accordance with all applicable local, state, and federal
transportation regulations. Fresh GAC transported onto the site will not be
a hazardous waste and standard shipping regulations will apply. Spent
GAC will be managed as a K045 hazardous waste. (K045 is the hazardous
waste number assigned under the Resource Conservation and Recovery Act
[RCRA] for spent carbon from the treatment of wastewater containing
explosives.) A limit of ten percent by weight explosives loading on the
GAC to be sent off site is set in order to ensure that the GAC will not be a
characteristic RCRA hazardous waste for reactivity. In addition, spent
GAC will be evaluated to determine if it exhibits the toxicity hazardous
waste characteristic (e.g., due to 2,4-DNT content). This evaluation will
include testing if necessary. Spent GAC will be manifested and
transported in accordance with all applicable regulatio,ns.
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In order to ensure that the off-site thennal treatment-does not contribute to
present or future environmental problems, the selection of a 'thermal
treatment facility' will follow the procedures presented in Procedures for
Planning and Implementing Off-Site Response Actions, 58 FR 49200,
September 22, 1993.
Backup Technologies
UV/Ox will be the back-up technology for groundwater treatment, to be
used in the unlikely event that thennal destruction of ordnance compounds
adsorbed onto GAC proves impracticable.
If a specific batch of spent GAC is not accepted for thermal regeneration
(due, for example, to an unacceptably high ordnance loading), it will either
be used as a supplemental fuel in a cement kiln or, as a last resort,
incinerated. '
Affirmation of the Statutory Determinations
Considering the new information that has been developed for the Site F
IRA, the lead agency believes that the remedy as changed is protective of
human health and the environment, complies with federal and state
requirements that were identified in the ROD as applicable or relevant and
appropriate to this remedial action at the time the original ROD was
signed, and is cost-effective.' The revised remedy utilizes permanent
solutions. GAC was considered as an alternative treatment technology
during development and selection of the original remedy. It is now
considered to be equivalent to UV lOx in tenns of effectiveness and
implementability.
Public Participation Activities
Public notice of this ESD will be published in a major local newspaper.
Notice has been issued previously that the contents of the Administrative
Record File are available for public review and comment. The GAC
treatment technology has been discussed and presented to the public at
previous meetings conducted to explain the alternatives and selected
remedy for the Site F IRA. A fact sheet will be issued explaining this'
ESD.
14632S\ESDSITEF.DOC
Attachment:
Table 1 - Site F Interim Remedial Action Cost Estimates
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Table 1 - Site F Interim Remedial Action Cost Estimates
Cost in Thousands of Dollars
Current Estimatesl IRA ROD Estimates2
Groundwater Treatment Technology UV IOx3 GA<:4 UV/Ox GAC
Capital 2,000 1,300 1 ,200 900
Operation & Maintenance (O&M) 300 200 1,300 1,600
(Based on 2 years of operation)
Total Estimated Cost 2,300 1,500 2,500 2,500
Current capital estimates are based on a 300 gpm design flow rate, with 15
percent contingency. Current O&M estimates assume a typical operating
flow rate of 225 gpm.
2
The IRA ROD cost estimates assume a flow rate of 200 gpm (both design
and actual operation) with no contingency.
3
Current UV lOx treatment cost estimates are based on quotes provided by
Solarchem during the UV/Oxidation Treatability Study performed for Site
F.
4
Current GAC treatment cost estimates are based on quotes provided by
Calgon Carbon Corporation.
14632S\ESDSITEF.DOC
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EXPLANATION OF SIGNIFICANT DIFFERENCES
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