Final Report
Pilot Region-Based Optimization
Program for Fund-Lead Sites
in EPA Region 3
Site Optimization Tracker:
Standard Chlorine of Delaware
Superfund Site
New Castle County, Pennsylvania
EPA Region III
£\ '-.
3J
Q
o
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Solid Waste and EPA 542-R-06-006g
Emergency Response December 2006
(5102P) www.epa.gov
Pilot Region-Based Optimization Program
for Fund-Lead Sites in EPA Region 3
Site Optimization Tracker:
Standard Chlorine of Delaware Superfund Site
New Castle County, Pennsylvania
EPA Region III
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Site Optimization Tracker:
Standard Chlorine of Delaware Superfund Site
New Castle County, Delaware
EPA Region III
December 30, 2005
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SECTION 1:
CURRENT SITE INFORMATION FORM
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Date:
12/30/2005
Filled Out By: GeoTrans, Inc.
A. Site Location, Contact Information, and Site Status
1. Site name 2. Site Location (city and State) 3. EPA Region
Standard Chlorine of Delaware New Castle County, DE 3
4a. EPA RPM 5a. State Contact
Mr. Hilary Thornton Ms. Lynn Krueger
4b. EPA RPM Phone Number 5b. State Contact Phone Number
215-814-3323 302-395-2632
4c. EPA RPM Email Address 5c. State Contact Email Address
Thornton.hilary@epa.gov lynn.krueger@state.de.us
5. Is the ground water remedy an interim remedy or a final remedy? Interim^) Final I I
6. Is the site EPA lead or State-lead with Fund money? EPA |/\l State I I
B. General Site Information
1 a. Date of Original ROD for Ground Water Remedy
3/09/1995
2a. Date of Projected O&F
1995 ROD O&F date planned for 9/07
3 . What is the primary goal of the designed P&T
system (select one)?
|y\| Contaminant plume containment
1 1 Aquifer restoration
1 1 Containment and restoration
1 1 Well-head treatment
lb. Dates of Other Ground Water Decision Documents (e.g., ESD, ROD Amendment)
Final GW ROD Planned for 9/2007
2b. Date for Projected Transfer to State
1995 ROD O&F date planned for 9/07
4. Check those classes of contaminants that are
contaminants of concern at the site.
K| VOCs (e.g., TCE, benzene, etc.)
Kl SVOCs (e.g., PAHs, PCP, etc.)
1 1 metals (e.g., arsenic, chromium, etc.)
1 1 other
5. Has NAPL or evidence of NAPL been observed at the site? Yes 1X1 No I I
,„,,.,,.,, . „ 60 gpm with capacity for
6. What is the designed total pumping rate ! -„
78 gpm
7. How many extraction wells
(or trenches) are there based on 6
design?
9. How many samples are proposed to
be collected from monitoring wells or . »
piezometers each year? (e.g., 40 if 10 ~
wells are sampled quarterly)
1 1 . What above-ground treatment processes are prop
IXI Air stripping
IXI Carbon adsorption (liquid phase only)
1 I Filtration
IXI Off-gas treatment
1 I Ion exchange
8. How many monitoring wells are ^ „
proposed to be regularly sampled? ~
10. How many process monitoring samples
(e.g., extraction wells, influent, effluent, etc.)
are proposed to be collected and analyzed ~100
each year? (e.g., 24 if influent and effluent
are sampled monthly)
>osed (check all that apply)?
IXI Metals precipitation
1 1 Biological treatment
O UV/Oxidation
| | Reverse osmosis
O Other
12. What is the anticipated percentage of system downtime per year? 10% |XI 10-20%O >20% I I
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C. Site Costs
1. Projected Annual O&M costs
O&M Category
Labor: project management, reporting,
technical support
Labor: system operation
Labor: ground water sampling
Utilities: electricity
Utilities: other
Consumables (GAC, chemicals, etc.)
Discharge or disposal costs
Analytical costs
Other (parts, routine maintenance, etc.)
O&M Total
Projected Annual Costs for
System Start-up (e.g., year 1)
Unknown
$93,600
Unknown
$29,000
Unknown
$320,000
Unknown
$24,000
$87,800
>$554,400
Projected Annual Costs for
Steady-State Operation
(e.g., after year 1)
Unknown
$93,600
Unknown
$29,000
Unknown
$160,000
Unknown
$24,000
$87,800
>$394,400
The O&M total should be equal to the total O&M costs for the specified fiscal years, including oversight from
USAGE or another contractor. For costs that do not fit in one of the above cost categories, include them in the
"Other" category. If it is not possible to break out the costs into the above categories, use the categories as best
as possible and provide notes in the following box.
2. Non-routine or other costs
Unknown
Unknown
Additional costs beyond routine O&M for the specified fiscal years should be included in the above spaces. Such
costs might be associated with additional investigations, non-routine maintenance, additional extraction wells, or
other operable units. The total costs billed to the site for the specified fiscal years should be equal to the O&M
total plus the costs entered in item 2.
3. Estimated costs for system design
and/or construction
$5.7 million
Notes on costs:
The design and construction costs are for the barrier wall and the P&T system. The P&T
system is scheduled to come online in FY06.
The O&M "start-up" costs provided above refer to the first three years of O&M when pumping
will occur at 60 gpm to lower the water table within the area enclosed by the barrier wall.
The "steady-state" O&M costs provided above refer to the years after the first three years when
pumping will occur at 30 gpm to maintain a lower water table within the area enclosed by the
barrier wall.
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D. Five-Year Review
1. Date of the Most Recent Five-Year Review N/A
2. Protectiveness Statement from the Most Recent Five-Year Review
I | Protective I I Not Protective
Protective in the short-term Determination of Protectiveness Deferred
3. Please summarize the primary recommendations in the space below
The first five-year review is planned for 5/15/2009.
E. Other Information
If there is other information about the site that should be provided please indicate that information in the space
below. Please consider enforcement activity, community perception, technical problems to be addressed, and/or
areas where a third-party perspective may be valuable.
Another aspect of the site that will require remediation is the wetlands. The cost for
addressing the wetlands is not included in the above costs for the barrier wall and P&T system.
Site team estimates for the wetlands remediation exceed $10 million.
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SECTION 2:
FOLLOW-UP HISTORY AND SUMMARIES
Note: Follow-up summaries are provided in reverse chronological order and include updated
and/or new recommendations.
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FOLLOW-UP HISTORY
Date of Original Optimization Evaluation
February 10, 2005 (Evaluation meeting)
August 5, 2005 (Final Report)
Meeting Date
July 13, 2005
October 19, 2005
Report Date
Item
August 5, 2005 Follow-Up #1 (conducted as part of pilot project)
December 30, 2005 Follow-Up #2 (conducted as part of pilot project)
Follow-Up #3
Follow-Up #4
Follow-Up #5
Follow-Up #6
Follow-Up #7
Follow-Up #8
"x" in box indicates the item has been completed
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SUMMARY OF FOLLOW-UP #2
Site or System Name
Date of This Follow-Up Summary
Date of Follow-Up Meeting or Call
(Indicate if Meeting or Call)
Standard Chlorine of Delaware Superfund Site
December 30, 2005
October 19, 2005 - Meeting
ROET MEMBERS CONDUCTING THE FOLLOW-UP EVALUATION:
Name
Norm Kulujian
Kathy Davies
Kathy Yager
Paul Leonard
Peter Rich
Rob Greenwald
Doug Sutton
Steve Chang
Affiliation
U.S. EPA Region 3
U.S. EPA Region 3
U.S. EPA Region 3
U.S. EPA Region 3
GeoTrans, Inc.
GeoTrans, Inc.
GeoTrans, Inc.
U.S. EPAOSRTI
Phone
215-814-3130
215-814-3315
617-918-8362
215-814-3350
410-990-4607
732-409-0344
732-409-0344
703-603-9017
Email
kuJuiiaruiQjTn@cpa.gOY
davies .kathv@epa. gov
illgeiliMUlMliSMllLIJ^
leonard.pauli3jepa.Kov
ElMl@SISl21Jl>iJlLSM
rgrccnwald@gcotransinc.com
dsuttoji@.ggojjgnsinc.com
chang.stcvcn@cpa.gov
SITE TEAM MEMBERS (INCLUDING CONTRACTORS) INTERVIEWED
Name
Hilary Thornton
Affiliation
U.S. EPA Region 3 (RPM)
Phone
215-814-3323
Email
|hornton.hilaj\@c|)a._goy
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IMPLEMENTATION STATUS OF ALL RECOMMENDATIONS UNDER CONSIDERATION BUT NOT
PREVIOUSLY IMPLEMENTED
Recommendation
Recommendation
Reason
E-2.1 Further Investigate the Presence of Contamination in the Potomac Aquifer
Protectiveness
Implementation
Status
Alternative in progress
Comments: The site team has commissioned the USGS to conduct a study of aquifer properties and aquifer
usage in the area. The study is titled "Delaware City Potomac Aquifer Study" and will include surveying water
usage in the area, installing of additional monitoring wells, tracking water levels to see if the site is influenced
by pumping from production wells, and perhaps redoing a pump test that had been previously conducted. An
interagency agreement with the USGS is in place. The workplan and QAPP were completed during summer
2005, and water level instrumentation was also installed in Summer 2005. Water level measurements will
begin in Fall 2005, and this phase of the study should be complete in Spring 2006. The budget is $150,000.
New monitoring wells in the Potomac are not scoped as part of the study, but are expected to be a follow-up
item to the study. The State would like to better understand shallow ground water flow before installing new
Potomac monitoring wells to reduce the potential for creating preferential pathways between the Columbia and
Potomac aquifers. Additional monitoring wells in the Potomac will likely be installed as a follow-up to the
USGS study in Summer 2006.
Recommendation
Recommendation
Reason
E-2.2 Compare Anticipated Full-Scale Costs of Chemical Oxidation for
Downgradient Plume with the Costs of Additional Extraction in the Same Area
Cost Reduction
Implementation
Status
Implemented
Comments: The site team reports that analyses have been done, and the final design includes discussion
regarding additional extraction wells in the downgradient area that would be tied to the treatment plant. The
final design also discusses the potential for a second wall if DNAPL is found downgradient of the currently
planned wall.
Recommendation
E-2.3 Reevaluate Costs of Capping Northern Area of Site to Limit Infiltration and
Reduce Extraction Rate
Recommendation
Reason
Cost Reduction
Implementation
Status
Alternative implemented
Comments: The final design does not include a cap. Further discussion of the cap has been postponed until the
remedy is up and running and the site team has a better understanding of the site hydrogeology under pumping
conditions.
Recommendation
Recommendation
Reason
E-2.4 Consider the Potential for On-Site Regeneration of Vapor Phase GAC
Cost Reduction
Implementation
Status
Implemented
Comments: The site team has reviewed the potential application of on-site regeneration of vapor phase GAC
and has concluded that the payback period is approximately 5 to 6 years. Given this payback period, the site
team is moving forward with the more traditional off-site regeneration of GAC, which has lower capital costs.
Room has been left in the treatment plant design to incorporate on-site regeneration at a later date if operating
conditions suggest it would be more cost-effective.
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Recommendation
Recommendation
Reason
Fl-1 Consider Constructing P&T System Before Constructing Barrier Wall
Cost Reduction & Technical
Improvement
Implementation
Status
Implemented
Comments: The site team has considered this recommendation and is planning to move forward with parallel
construction of the P&T system and barrier wall. The site team is planning to complete the barrier wall in one
mobilization rather than the previously considered two mobilizations. This approach of parallel tracks for the
P&T system and the barrier wall addresses the concerns identified by the ROET in its original recommendation.
Recommendation
Recommendation
Reason
Fl-2 Avoid Substantial Investment for DNAPL Recovery
Cost Reduction
Implementation
Status
Implemented
Comments: The site team has considered this recommendation and is moving forward in a manner consistent
with the ROET recommendation. Additional efforts will not be focused on looking for and recovering DNAPL.
However, the extraction wells will be completed to the clay layer to intercept DNAPL if it is present, and the
treatment system will include an oil/water separator to address DNAPL if is present in the extracted water.
Key for recommendation numbers:
• E denotes a recommendation from the original optimization evaluation
• Fl, F2, etc. denote recommendations from the first, second, etc. follow-up meeting
* The number corresponds to the number of the recommendation as stated in the optimization
evaluation or follow-up summary where the recommendation was provided
RECOMMENDATIONS PREVIOUSLY IMPLEMENTED OR THAT WILL NOT BE IMPLEMENTED
None.
OTHER CHANGES, UPDATES, OR SIGNIFICANT FINDINGS SINCE LAST FOLLOW-UP
• The final design for the barrier wall and P&T system was completed in Summer 2005
and approved in September 2005. The site team is currently in the contracting phase and
is planning to mobilize in Spring/Summer 2006 for construction.
NEW OR UPDATED RECOMMENDATIONS FROM THIS FOLLOW-UP
1. If DNAPL is found downgradient of the planned barrier wall, the ROET encourages the
site team to fully consider the limitations of a second, smaller barrier wall if there is no
competent aquitard in the area for the wall to be keyed into. The site team might
consider initially extracting and treating ground water in this downgradient area and
monitoring potential DNAPL migration before considering a barrier wall, trench, or other
more active DNAPL remedy.
2. The site team should revisit discussions with the Regional toxicologists and ecologists
about wetlands remediation. The proposed remedy using in-situ chemical oxidation
would be costly and would likely sterilize/destroy the wetlands, eliminating the primary
reason for remediating them. Technical Assistance Item #3 in Appendix A offers
considerations regarding potentially more cost-effective options for wetlands
remediation.
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SUMMARY OF FOLLOW-UP #1
Site or System Name
Date of This Follow-Up Summary
Date of Follow-Up Meeting or Call
(Indicate if Meeting or Call)
Standard Chlorine of Delaware Superfund Site
August 5, 2005
July 13, 2005 -Meeting
ROET MEMBERS CONDUCTING THE FOLLOW-UP EVALUATION:
Name
Norm Kulujian
Peter Schaul
Kathy Davies
Peter Rich
Rob Greenwald
Doug Sutton
Kathy Yager (by phone)
Affiliation
U.S. EPA Region 3
U.S. EPA Region 3
U.S. EPA Region 3
GeoTrans, Inc.
GeoTrans, Inc.
GeoTrans, Inc.
U.S. EPAOSRTI
Phone
215-814-3130
215-814-3183
215-814-3315
410-990-4607
732-409-0344
732-409-0344
617-918-8362
Email
kuluiian.nomi@cpa.sov
schaul.peter@epa. gov
prich@geotraiisinc.coni
llEOTwak|@Lg^^
dsutton.@gcotransinc.com
yagcjjcathyj^cj3jinjail.cpa.ggv
SITE TEAM MEMBERS (INCLUDING CONTRACTORS) INTERVIEWED
Name
Hilary Thornton
Bernice Pasquini
Affiliation
U.S. EPA Region 3 (RPM)
U.S. EPA Region 3 (Hydro)
Phone
215-814-3323
215-814-3326
Email
thojTUgjiJiilaiy@cj3g.gov
pasquini.bcmicc@cpa.gov
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IMPLEMENTATION STATUS OF PREVIOUSLY IDENTIFIED RECOMMENDATIONS
Recommendation
Recommendation
Reason
2.1 Further Investigate the Presence of Contamination in the Potomac Aquifer
Protectiveness
Implementation
Status
Alternative in progress
Comments: The site team has commissioned the USGS to conduct a study of aquifer properties and aquifer usage
in the area. The study is titled "Delaware City Potomac Aquifer Study" and will include surveying water usage in
the area, installing of additional monitoring wells, tracking water levels to see if the site is influenced by pumping
from production wells, and perhaps redoing a pump test that had been previously conducted. The study should be
conducted within one year. The budget is approximately $150,000. This scope is larger than that suggested by
the evaluation team, but the evaluation team agrees that the collection of the additional information would be
useful for the site design. The site team will provide the evaluation report to the USGS so that it can consider the
recommendations for well placement provided in the optimization evaluation report.
Recommendation
2.2 Compare Anticipated Full-Scale Costs of Chemical Oxidation for Downgradient
Plume with the Costs of Additional Extraction in the Same Area
Recommendation
Reason
Cost Reduction
Implementation
Status
Delayed
Comments: The site team will consider how to address the downgradient contamination as part of the final
remedy, and this consideration will depend, in part, on how the concentrations downgradient of the barrier wall
enclosure respond to the containment effort. The site team recognizes that chemical oxidation may be costly
relative to other remedial approaches for this downgradient location.
Recommendation
Recommendation
Reason
2.3 Reevaluate Costs of Capping Northern Area of Site to Limit Infiltration and
Reduce Extraction Rate
Cost Reduction
Implementation
Status
Delayed
Comments: The site team will consider whether or not to cap the northern area as part of the final remedy, and
this consideration will depend, in part, on how well the barrier wall and P&T system are able to cost-effectively
provide containment.
Recommendation
Recommendation
Reason
2.4 Consider the Potential for On-Site Regeneration of Vapor Phase GAC
Cost Reduction
Implementation
Status
Substantial progress
Comments: The site team is considering this recommendation as part of the 95% design, which is expected by
the end of July 2005.
OTHER CHANGES, UPDATES, OR SIGNIFICANT FINDINGS SINCE LAST FOLLOW-UP
The USGS will be conducting a study of the Potomac aquifer in the vicinity of the site (as
discussed in the update to Recommendation 2.1.
Finalization of the barrier wall and P&T system design is expected by the end of FY05,
and contracting for construction of both the P&T system and barrier wall should begin in
Fall 2005 (i.e., the beginning of FY06). Construction is anticipated to begin in Spring
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2006 and to take approximately 12 months.
$4.2 million in funding for construction of the barrier wall and P&T system has been
allocated to the project. Additional funding (up to $5.7 million total) may be required.
NEW OR UPDATED RECOMMENDATIONS FROM THIS FOLLOW-UP
1. The site team has been planning to install the barrier wall prior to installing the P&T
system. The evaluation team suggests that the site team consider construction of the P&T
system prior to construction of the barrier wall. Technical Assitance Item #1 in
Appendix A provides some ideas related to sequencing for the site team to consider.
2. DNAPL has been recovered at the site previously. The evaluation team suggests
avoiding substantial investment in a DNAPL recovery system given the high mass
removal that this anticipated from the P&T system, the limited amount of DNAPL that
would likely be recovered, the containment that will be offered by the barrier wall and
P&T system, and the long time horizon for P&T system operation. The evaluation team
provides additional information on this suggestion in Technical Assitance Item #2 in
Appendix A.
NEW OR UPDATED RECOMMENDATIONS FROM Tins FOLLOWUP - OTHER
• None.
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UPDATED COST SUMMARY TABLE
Recommendation
Reason
Implementation
Status
Estimated
Capital Costs
($)
Actual Capital
Costs
($)
Estimated
Change in Annual
Costs
($/yr)
Actual Change
in Annual Costs
($/yr)
Original Optimization Evaluation Recommendations
2. 1 Further Investigate the Presence of
Contamination in the Potomac Aquifer
2.2 Compare Anticipated Full-Scale
Costs of Chemical Oxidation for
Downgradient Plume with the Costs of
Additional Extraction I the Same Area
2.3 Reevaluate Costs of Capping
Northern Area of Site to Limit Infiltration
and Reduce Extraction Rate
2.4 Consider the Potential for On-Site
Regeneration of Vapor Phase GAC
Protectiveness
Protectiveness
Protectiveness
Protectiveness
Alternative in
Progress
Implemented
Alternative
Implemented
Implemented
$75,000
$0
$0
$0
$150,000
$0
$0
$0
$0
$0
$0
New or Updated Recommendations from Follow-up #1, July 13, 2005
1. Consider constructing P&T system
before constructing barrier wall
2. Avoid substantial investment for
DNAPL recovery
Cost Reduction
&
Technical
Improvement
Cost Reduction
Implemented
Implemented
$0
$0
$0
$0
New or Updated Recommendations from Follow-up #2, October 19, 2005
1. Consider limitations of a
downgradient, smaller barrier wall if
there is no competent aquitard in the area
2. Considerations for wetlands
remediation
Cost Reduction
Protectiveness
Cost Reduction
$0
$0
Costs in parentheses imply cost reductions.
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APPENDIX: A
ARCHIVE OF TECHNICAL ASSISTANCE PROVIDED BY THE ROET
Note: Technical assistance items are provided in reverse chronological order.
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Technical Assistance Item #4
Presented December 30, 2005
Considerations for contracting construction of the barrier wall
Due to the relatively small number of contractors able to provide the construction services for
the barrier wall and a desire to complete construction in one mobilization during the upcoming
construction season, the ROET has the following ideas to consider for the associated contracting.
One potential option for structuring the request for proposal is to ask contractors to bid on
completing 25%, 50%, 75%, or 100% of the wall and providing unit rates under each of those
scenarios for completing additional portions of the wall. For the 100% option, the request for
proposal could ask for costs associated with committing either one or two rigs to the job. The
site team should attempt to obtain at least three competitive bids. The three bids can then be
compared and one or more bids could be accepted. The costs for using one contractor with one
rig, one contractor with two rigs, and multiple contractors can then be compared. The site team
can then weigh the additional costs of some items against the benefits of potentially completing
the job faster (because more than one rig is being used) and/or the benefits of redundancy in
having multiple rigs in case there are problems with one rig. The bidders should not be
constrained to bidding on the whole job. There should be flexibility, allowing them to bid on all
scenarios or just some of the scenarios. By providing this flexibility and the number of options,
smaller firms might bid on a fraction of the wall that might not have been able to bid on the
whole job.
Although this makes for a more complex request for proposal, it provides the site team with
more options. In addition, although managing multiple contractors is more complicated than
managing a single contractor, the added security of using more than one contractor may
outweigh the complications of managing multiple contractors.
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Technical Assistance Item #3
Presented December 30, 2005
Considerations for alternative wetland remediation
The site team has indicated that consideration of in-situ chemical oxidation and other aggressive
remedies for the impacted wetlands at an approximate cost of well over $10 million. The site
team has also indicated, however, that Regional toxicologists are concerned that chemical
oxidation or these other remedies will damage the wetlands.
After considering the possibility of excavation or chemical oxidation, which would definitively
destroy the wetlands, the toxicologists and ecologists may prefer to leave the contamination in
place. This approach would be based on a conclusion that having the current wetlands impacted
by contamination is of more value destroying the wetlands as a result of the remediation.
If the above approach is unacceptable from a risk perspective, the site team could consider a
containment approach. Rather than undertake aggressive remediation of the wetlands, it would
likely be cost-effective to isolate the contaminated wetlands and cover them with an appropriate
cap. Although this option would destroy the wetlands, so would any other option that would
effectively address the contamination. To mitigate the effect of the lost wetlands from this or
any other remedial approach, the site team might be able to replace them with newly constructed
wetlands in another location.
It is recommended that the site team consider several remedial options and then discuss the
potential for either taking no aggressive action with the wetlands or potentially containing the
contamination and reconstructing the wetlands in a new location.
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Technical Assistance Item #2
Presented August 5, 2005
Considerations for DNAPL Recovery at the Standard Chlorine of Delaware Superfund Site
The optimization evaluation team understands DNAPL has been recovered as free product from
multiple site wells but that the recovery was fairly limited (approximately 10 gallons over
several recovery events). The following are considerations for future DNAPL recovery at the
site given the current understanding of site conditions and the anticipated performance of the
planned P&^arrier wall remedy.
• As documented in Section 2.4 of the optimization evaluation for this site, the planned
P&T system may remove as much as 20,000 pounds of volatile organic compounds per
year during the first three years and perhaps 10,000 pounds per year during subsequent
years. These mass removal rates translate to approximately 2,200 gallons per year and
1,100 gallons per year of DNAPL recovery during those two time periods, respectively,
assuming a specific density equal to that of chlorobenzene (approximately 1.11). The
recovery of 10 gallons over several events is small (approximately 1%) by comparison.
• The planned remedy is anticipated to provide containment in both the horizontal and
vertical directions, and aquifer restoration is not anticipated to occur in a reasonable time
frame. As such, DNAPL recovery efforts, if they are to occur should be cost-effective
relative to other mass removal occurring at the site. Given that past recovery efforts have
been limited, regular DNAPL recovery events should probably not be scheduled. Rather,
DNAPL should likely be collected only when it is observed during routine well gauging
events.
• The cost per gallon of contamination removed by the P&T system will be approximately
$250 to $500 per gallon assuming an annual O&M cost of $500,000 per year. This range
of values ($250 to $500 per gallon of contaminants) can serve as a reasonable standard
for determining whether or not additional DNAPL removal efforts are cost effective.
• During the next several monitoring events (e.g., four quarterly events) the site team can
observe the presence of DNAPL and estimate the recoverable volume by multiplying the
DNAPL thickness by the borehole area. If the site team observes a combined recoverable
volume of more than 10 gallons from site wells, the site team could purchase a dedicated
total fluids pump to use for future DNAPL recovery. To be cost-effective, the DNAPL
recovery events should only occur during the routine monitoring events if sufficient
volume (e.g., 10 gallons) of recoverable product is present.
• Due to the containment and mass removal achieved by the P&T system, the optimization
evaluation team discourages the installation of additional wells or the design and
construction of an automated DNAPL recovery system at this point.
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Technical Assistance Item #1
Presented August 5, 2005
Considerations for Sequencing Barrier Wall andP&TSystem Construction
The optimization evaluation team understands that the site team is currently planning on
constructing the barrier wall (with the exception of one small downgradient portion) before
constructing the P&T system. The small portion would be left open to prevent water from
infiltration from pooling within the barrier wall enclosure and would be constructed in a separate
mobilization after the P&T system begins operating. The optimization team believes there are
several reasons to change the sequencing so that the P&T system is constructed prior to the
barrier wall.
• Neither aspect of the remedy will provide full containment on its own. If the barrier wall
is constructed first, contaminated water will still be able to discharge through the planned
opening until it is closed after the P&T system comes on line. Similarly, if the P&T
system is constructed first, it will provide partial containment, but the extraction rate will
not be sufficient to provide full containment, especially in the vertical direction, until the
barrier wall is constructed. Therefore, temporary incomplete capture should not be a
determining factor in which item should be constructed first.
• A P&T system will typically undergo three to six months of start-up to ensure that the
extraction and treatment systems are performing as designed and to correct potential
problems that were not anticipated during design. If the P&T system is installed prior to
the barrier wall, then the start-up period of three to six months can occur while the site
team is constructing the barrier wall. However, if the barrier wall is constructed first
(with the exception of the small downgradient portion), then a partially completed barrier
wall will need to remain in place while the P&T system is constructed and for several
more months while the P&T system is tested. Therefore, with a proper start-up period for
the P&T system, the overall remedy should be completed sooner if construction begins
with the P&T system. If the P&T system is not properly tested during a start-up period
and the barrier wall enclosure is finalized, failures in the P&T system will result in water
pooling up inside the barrier wall enclosure.
• The P&T system will yield valuable information about the site hydrogeology. For
example, the actual yield of the extraction system might be lower than the design yield.
By constructing the P&T system and monitoring it during the start-up period, the site
team can determine at an earlier date if additional extraction wells will be needed.
Constructing the majority of the barrier wall and then the P&T system and then finalizing
the barrier wall would require two mobilizations of the barrier wall crew. This would
likely be more costly, and there might be delays if the crew is not immediately available
for either of these mobilizations.
• By constructing the P&T system first and beginning its operation, the site team will be
able to better control water levels within the barrier wall enclosure as the barrier wall is
constructed. If there is substantial precipitation and infiltration, barrier wall construction
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could be disrupted if water levels rise to an unacceptable level, particularly at the
downgradient end of planned barrier wall enclosure.
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APPENDIX: B
BASELINE SITE INFORMATION SHEET AND
OPTIMIZATION EVALUATION REPORT
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Streamlined
Optimization Evaluation Report
Standard Chlorine of Delaware Superfund Site
New Castle County, Delaware
EPA Region III
August 5, 2005
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SECTION 1:
BASELINE SITE INFORMATION FORM
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Date: 8/5/05
Filled Out By: Douglas Sutton (GeoTrans)
A. Site Location, Contact Information, and Site Status
1. Site name 2. Site Location (city and State) 3. EPA Region
Standard Chlorine of Delaware New Castle County, DE 3
4a. EPA RPM 5a. State Contact
Mr. Hilary Thornton Ms. Lynn Krueger
4b. EPA RPM Phone Number 5b. State Contact Phone Number
215-814-3323 302-395-2632
4c. EPA RPM Email Address 5c. State Contact Email Address
Thornton.hilary@epa.gov lynn.krueger@state.de.us
5. Is the ground water remedy an interim remedy or a final remedy? Interim^] Final I I
6. Is the site EPA lead or State-lead with Fund money? EPA |/\l State I I
B. General Site Information
1 a. Date of Original ROD for Ground Water Remedy
3/09/1995
2a. Date of Projected O&F
1995 ROD O&F date planned for 9/07
3 . What is the primary goal of the designed P&T
system (select one)?
|y\| Contaminant plume containment
1 1 Aquifer restoration
1 1 Containment and restoration
1 1 Well-head treatment
lb. Dates of Other Ground Water Decision Documents (e.g., ESD, ROD Amendment)
Final GW ROD Planned for 9/2007
2b. Date for Projected Transfer to State
1995 ROD O&F date planned for 9/07
4. Check those classes of contaminants that are
contaminants of concern at the site.
K| VOCs (e.g., TCE, benzene, etc.)
Kl SVOCs (e.g., PAHs, PCP, etc.)
1 1 metals (e.g., arsenic, chromium, etc.)
1 1 other
5. Has NAPL or evidence of NAPL been observed at the site? Yes 1X1 No I I
,„,,.,,.,, . „ 60 gpm with capacity for
6. What is the designed total pumping rate ! -„
78 gpm
7. How many extraction wells
(or trenches) are there based on 6
design?
9. How many samples are proposed to
be collected from monitoring wells or . »
piezometers each year? (e.g., 40 if 10 ~
wells are sampled quarterly)
1 1 . What above-ground treatment processes are prop
IXI Air stripping
IXI Carbon adsorption (liquid phase only)
1 I Filtration
IXI Off-gas treatment
1 I Ion exchange
8. How many monitoring wells are ^ „
proposed to be regularly sampled? ~
10. How many process monitoring samples
(e.g., extraction wells, influent, effluent, etc.)
are proposed to be collected and analyzed ~100
each year? (e.g., 24 if influent and effluent
are sampled monthly)
>osed (check all that apply)?
IXI Metals precipitation
1 1 Biological treatment
O UV/Oxidation
| | Reverse osmosis
O Other
12. What is the anticipated percentage of system downtime per year? 10% |XI 10-20%O >20% I I
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C. Site Costs
1. Projected Annual O&M costs
O&M Category
Labor: project management, reporting,
technical support
Labor: system operation
Labor: ground water sampling
Utilities: electricity
Utilities: other
Consumables (GAC, chemicals, etc.)
Discharge or disposal costs
Analytical costs
Other (parts, routine maintenance, etc.)
O&M Total
Projected Annual Costs for
System Start-up (e.g., year 1)
Unknown
$93,600
Unknown
$29,000
Unknown
$320,000
Unknown
$24,000
$87,800
>$554,400
Projected Annual Costs for
Steady-State Operation
(e.g., after year 1)
Unknown
$93,600
Unknown
$29,000
Unknown
$160,000
Unknown
$24,000
$87,800
>$394,400
The O&M total should be equal to the total O&M costs for the specified fiscal years, including oversight from
USAGE or another contractor. For costs that do not fit in one of the above cost categories, include them in the
"Other" category. If it is not possible to break out the costs into the above categories, use the categories as best
as possible and provide notes in the following box.
2. Non-routine or other costs
Unknown
Unknown
Additional costs beyond routine O&M for the specified fiscal years should be included in the above spaces. Such
costs might be associated with additional investigations, non-routine maintenance, additional extraction wells, or
other operable units. The total costs billed to the site for the specified fiscal years should be equal to the O&M
total plus the costs entered in item 2.
3. Estimated costs for system design
and/or construction
$5.7 million
Notes on costs:
The design and construction costs are for the barrier wall and the P&T system. The P&T
system is scheduled to come online in FY06.
The O&M "start-up" costs provided above refer to the first three years of O&M when pumping
will occur at 60 gpm to lower the water table within the area enclosed by the barrier wall.
The "steady-state" O&M costs provided above refer to the years after the first three years when
pumping will occur at 30 gpm to maintain a lower water table within the area enclosed by the
barrier wall.
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D. Five-Year Review
1. Date of the Most Recent Five-Year Review N/A
2. Protectiveness Statement from the Most Recent Five-Year Review
I | Protective I I Not Protective
Protective in the short-term Determination of Protectiveness Deferred
3. Please summarize the primary recommendations in the space below
The first five-year review is planned for 5/15/2009.
E. Other Information
If there is other information about the site that should be provided please indicate that information in the space
below. Please consider enforcement activity, community perception, technical problems to be addressed, and/or
areas where a third-party perspective may be valuable.
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SECTION 2:
STREAMLINED OPTIMIZATION EVALUATION
FINDINGS AND RECOMMENDATIONS
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Standard Chlorine of Delaware Superfund Site
Date of Evaluation Meeting: February 10, 2005 Date of Final Report: Augusts, 2005
ROET MEMBERS CONDUCTING THE STREAMLINED OPTIMIZATION EVALUATION:
Name
Peter Ludzia
Peter Schaul
Kathy Davies
Norm Kulujian
Peter Rich
Doug Sutton
Chuck Sands
Jean Balent (by phone)
Affiliation
U.S. EPA Region 3 (Section
Chief)
U.S. EPA Region 3 (Branch Chief)
U.S. EPA Region 3
U.S. EPA Region 3
GeoTrans, Inc.
GeoTrans, Inc.
U.S. EPAOSRTI
U.S. EPAOSRTI
Phone
215-814-3190
215-814-3183
215-814-3315
215-814-3130
410-990-4607
732-409-0344
703-603-8857
202-564-1709
Email
1 ud/ia.pctcrfficpa. go v
schaul.peter@epa.gov
Davics.kallw.fficpa.gov
KuJujjaiLnojTrifficpagQY
prich@geotransinc.com
dsuttonffigeotransinc.com
Sands.chaTlcs@,epa..80v
Bajcntj_can@CBa._goy
SITE TEAM MEMBERS (INCLUDING CONTRACTORS) INTERVIEWED
Name
Hilary Thornton
Bernice Pasquini
Lynn Krueger (by phone)
Bob Asreen (by phone)
Chris Wolfe
Gary Snyder
Affiliation
U.S. EPA Region 3 (RPM)
U.S. EPA Region 3 (Hydro)
Delaware DNREC
Delaware DNREC
Black and Veatch
Black and Veatch
Phone
215-814-3323
215-814-3326
302-395-2632
Email
thornton.hilarvfficpa.gov
pasquini.bernicei@epa.gov
Lvnn.kruegerffistate.de. us
1.0 SIGNIFICANT FINDINGS BEYOND THOSE REPORTED ON SITE INFORMATION FORM
• The Standard Chlorine of Delaware (SCD) facility began operation in 1965 and
generated chlorinated benzene compounds by combining chlorine and benzene from
neighboring facilities. The original owner went bankrupt in 1998. The facility
1
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continued to operate through 2002 when the second owner went bankrupt. A pump and
treat (P&T) system was operated by the owners from September 1986 through
December 2001. Although the system removed over 1,000 pounds of contaminants per
month during operation between 1998 and 2001 (based on a quarterly monitoring
report submitted by the facility in January 2002), system operation was discontinued
because it was ineffective at containing the contaminant plume.
• The site team is currently at the 60% design stage for the interim ground water remedy,
which includes the following elements:
o Institutional controls in the form of deed restrictions to limit the use of
contaminated ground water
o Installation of a fully encircling slurry wall (barrier wall)
o Extraction and treatment of ground water in the shallow aquifer within the
slurry wall to maintain hydraulic control of the contamination
o The use of chemical oxidation or additional pumping to address contamination
that would remain outside of the barrier wall
o Associated performance monitoring
Although the 1995 ROD and the 2004 ROD Amendment discuss a remedy for
remaining contamination in above-ground storage tanks and for contaminated soils and
sediments, this optimization evaluation focuses on the interim ground water remedy
and potential considerations for the final ground water remedy. The primary reason for
this focus on ground water is because the site team has prepared the 60% design for the
ground water remedy and is specifically requesting feedback on this aspect of the site
remedy.
• The barrier wall as designed would be approximately 5,500 feet long, 2 to 4 feet thick,
approximately 70 feet deep, and in most locations will be keyed into a clay layer. The
anticipated permeability will be 10"7 cm/sec, and the anticipated effective life will be at
least 30 years. Because of constructability issues, the barrier wall, as designed, does
not extend to the shore of Red Lion Creek. Rather, the downgradient portion of the
wall will be approximately 700 feet upgradient of the creek, leaving approximately 6 to
7 acres of contaminated soil and ground water between the downgradient portion of the
barrier wall and the creek. The estimated cost for the installation of the barrier wall is
approximately $3.5 million to $4 million, which is 60% to 70% of the interim ground
water remedy capital costs.
• A pilot test of in-situ chemical oxidation is being considered for the ground water
contamination outside of the barrier wall (based on results of planned in-situ chemical
oxidation study for wetland soils). Based on this pilot test, the site team will determine
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if in-situ chemical oxidation is a cost-effective means of addressing this contamination.
If it is not, the site team will likely install additional extraction wells to extract and
treat this contamination. As noted in the previous bullet, the area to be treated would
be approximately 6 to 7 acres.
• The site team provides two primary reasons for including a fully-encircling barrier wall
in the ground water remedy:
o By encircling the majority of the contamination, the amount of pumping that is
required is reduced from approximately 210 gpm (with a downgradient-only
barrier wall) to 60 gpm to maintain hydraulic capture. The reduced pumping
should reduce the future operating costs for the P&T system.
o By encircling the contamination and pumping within the area enclosed by the
wall, the water level within the wall could be reduced such that an upward
gradient between the shallow (Columbia) aquifer and deeper (Potomac) aquifer
is established. This upward gradient should limit or eliminate further
downward contaminant migration to the Potomac Aquifer, which is used for
drinking water.
• The proposed P&T system consists of the following components:
o 6 extraction wells (6 inches in diameter) installed to depth of approximately 70
feet below ground surface (bgs) and constructed of 316 stainless steel. The
extraction system will be designed to extract up to 78 gpm (the estimated 60
gpm that is needed for maintaining an upward gradient between the Columbia
and Potomac Aquifers plus a 30% design contingency).
o 5,000-gallon influent holding tank to blend extracted water and allow recovered
DNAPL (if any) to settle out of the process water
o Filtration system consisting of two 25-micron bag filters in parallel followed by
two 10-micron bags in parallel
o A low-profile air stripper with four trays
o Two 5,000-pound vapor phase granular activated carbon (GAC) units to treat
the air stripper offgas
o A secondary filtration system consisting of two 10-micron bag filters in parallel
o Two 2,500-pound liquid phase GAC units to serve as a polishing step for the air
stripper
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o pH adjustment through the addition of sodium hydroxide and oxidation through
potassium permanganate addition
o Metals removal with a green sand filter
o Potential use of ion exchange to remove copper and zinc if required to meet
discharge standard
o Discharge of treated water to Red Lion Creek or a conveyance that discharges
to Red Lion Creek
The following table provides the reported influent design criteria for select compounds
based on the most recent Remedial Investigation ground water sampling along with
potentially applicable discharge standards.
Compound
Benzene
Chlorobenzene
Dichlorobenzene isomers
Trichlorobenzene isomers
Tetrachlorobenzene isomers
Nitrobenzene
Aluminum
Calcium
Iron
Manganese
Copper
Zinc
Average Influent
Concentration
(ug/L)
9,890
29,598
31,349
4,726
290
374
11,078.8
27,574.8
21,951.7
10,040.4
Maximum Influent
Concentration (ug/L)
70,000
110,000
85,200
21,519
1,170
1,300
71,400
70,900
60,100
25,100
Potential Average
Discharge Limit*
(ug/L)
57
142
142**
196**
N/A
2,237
N/A
N/A
2,000
N/A
I 2***
95
* These standards are based on the NPDES permit previously maintained by the facility in 1998 assuming a
discharge rate of approximately 460 gpm. The actual standards for the proposed P&T system may differ.
** Listed standards are for 1,4-Dichlorobenzene and 1,2,4-Trichlorobenzene
*** An interim average copper standard of 300 ug/L applied for the first 37 months of operation. The provided
standard-was the "final" standard.
Data from the previously operated P&T system at the site provides an indication of the
contaminant concentrations under pumping conditions. In general, the influent
concentrations decreased by a factor of two to three at each of the previous recovery
wells over a two-year period; however, those extraction wells were located
downgradient from where treated water was reinfiltrated to the subsurface. A
comparison of the design average influent concentration with the contaminant
concentrations from monitoring wells and previous recovery wells that are located near
the proposed recovery well locations indicates that the design average influent
concentration is a reasonable approximation of the expected influent.
The site is underlain by the Columbia Aquifer, which consist of medium to coarse
grained sand with varying amounts of gravel. The aquifer is 70 to 100 feet thick and
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has interspersed lenses of clay or clayey silt. Ground water in the Columbia Aquifer
flows north toward Red Lion Creek. The average hydraulic gradient is 0.005 feet per
foot, and the hydraulic conductivity is estimated to range from 5 to 134 feet per day or
higher.
• The Columbia Aquifer is underlain in some areas by the Merchantville Formation,
which consists of generally silty clay and likely serves as a confining layer. In other
portions, the Columbia Aquifer is underlain by the clays and silts of the Upper Potomac
Aquifer. Recent monitoring in the Potomac Aquifer indicates the presence of site-
related contamination, which suggests that the silts and clays do not isolate the water-
bearing portions of the Potomac Aquifer from the contamination in the Columbia
Aquifer. The Potomac Aquifer flows to the southeast and is used for drinking water.
The site team is aware of residential wells approximately 0.75 miles to one mile north
and west of the site (upgradient in the Potomac Aquifer) and public wells
approximately three miles southeast of the site (downgradient in the Potomac Aquifer).
Other supply wells for nearby industries are also completed in the deeper portion of
the Potomac Aquifer and are located one to two miles south of the SCD facility.
• Site contaminants generally include benzene, chlorobenzene, dichlorobenzenes, and
trichlorobenzenes. The total concentration of all contaminants of concern is as high as
345,000 ug/L at MW-20 and exceeds 50,000 ug/L in at least 15 other monitoring wells.
The concentrations are indicative of DNAPL, and DNAPL has been observed as free
product in several site wells, including RW-2, RW-5, TW-5, TW-28, TW-30, and MW-
28. A few gallons have been pumped from some of these wells intermittently, but EPA
has not located a large continuous "pool" of recoverable DNAPL. The proposed barrier
wall encircles most of the area with elevated concentrations; however, some of the
highest concentrations on site have been detected in monitoring wells between the
proposed barrier wall and Red Lion Creek. At least nine of the site monitoring wells
with high levels of contamination (including MW-20, which has in excess of 300,000
ug/L of site-related contaminants) would be located downgradient of the proposed wall
enclosure. In addition, site-related contamination has been detected in the Potomac
Aquifer (e.g., 35 ug/L of benzene and 29 ug/L of chlorobenzene at PW-01).
2.0 CONSIDERATIONS FOR THE GROUND WATER REMEDY AND DESIGN
Because this site is in the design phase and does not have an operating remedy, this
evaluation is focused on providing suggestions for the site team to consider during design
and remedy implementation. The suggestions are geared toward designing and
implementing a protective and cost effective remedy, but because many of the suggestions
are provided for both protectiveness and cost-effectiveness reasons, the suggestions have
not been divided into the traditional four optimization evaluation categories of improving
effectiveness, reducing cost, improving technical operations, and gaining site closure.
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2.1 FURTHER INVESTIGATE THE PRESENCE OF CONTAMINATION IN THE POTOMAC
AQUIFER
A downward gradient is present between the Columbia and Potomac Aquifers at
monitoring well clusters MW-15/PW-1 and C-31/PW-2. In addition, site-related
contamination has been identified at PW-1. The site team is planning to investigate the
impacts in the Potomac Aquifer. This investigation should occur before plans for the
ground water remedy design are finalized. The optimization evaluation team provides
the following for the site team to consider when planning the investigation.
• The investigation should limit the number of borings through the most
contaminated area of the aquifer. New, deep aquifer monitoring wells should
therefore be installed outside of the known Columbia Aquifer plume.
• Based on areal photographs, the area to the east of the site (the downgradient side in
the Potomac Aquifer) is wooded and accessibility might be limited in places.
• MW-11 and MW-12, which are both Potomac Aquifer wells and located
downgradient of the site (MW-11 to the south and MW-12 to the east), have
undetectable concentrations of site-related contamination. These wells should serve
as the outer bounds of additional Potomac Aquifer investigation. Furthermore, the
gradient between the Columbia and Potomac Aquifers is upward closer to the creek
(e.g., near the OR-6 cluster). The upward gradient in this area and the ground water
flow to the southeast in the Potomac Aquifer makes it unlikely that contamination
will be able to migrate to the Potomac Aquifer and then impact it north of MW-12.
Based on these considerations, the optimization evaluation team would recommend the
installation of the following three new monitoring wells installed in the upper 50 feet of
the Potomac Aquifer:
• Midway (horizontally) between MW-11 and PW-2
• Co-located with MW-17
• Downgradient of PW-1 (i.e., the proposed location of PW-3)
Installation and sampling of these wells could likely be accomplished for
approximately $75,000, including documenting the results and determining the need for
further investigation.
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2.2 COMPARE ANTICIPATED FULL-SCALE COSTS OF CHEMICAL OXIDATION FOR
DOWNGRADIENT PLUME WITH THE COSTS OF ADDITIONAL EXTRACTION IN THE
SAME AREA
The proposed barrier wall would likely enclose much of the site-related contamination;
however, a 6 to 7 acre area of contamination (some of the highest concentrations on
site) would remain outside of the wall, outside of the influence of ground water
extraction, and adjacent to Red Lion Creek. The site team stated that they would
consider the use of in-situ chemical oxidation for this area.
Based on an estimated 25-foot radius of influence, approximately 140 injection points
would be required, and based on the elevated concentrations and the potential for
residual NAPL, multiple injections would be required. Given these parameters, the
optimization evaluation team estimates that the use of in-situ oxidation may require
approximately $2 million to design, test, apply, and evaluate. Furthermore, the
application of in-situ chemical oxidation could not guarantee that concentrations would
be low enough to avoid future ground water extraction and treatment in this area.
Given the uncertainty associated with this remedial approach and the cost, it is
recommended that the site team compare anticipated full-scale chemical oxidation costs
with the cost of pumping in this location. If the site contractor's expected full-scale
costs (which may be different than the $2 million mentioned in this report) are
substantially higher than the costs of additional pumping in this location, then the site
team may decide against piloting or further considering chemical oxidation for this
downgradient area.
2.3 REEVALUATE COSTS OF CAPPING NORTHERN AREA OF SITE TO LIMIT INFILTRATION
AND REDUCE EXTRACTION RATE
The site team is considering potentially capping the northern area of the site to limit
infiltration and reduce the amount of water that would be extracted from within the
barrier wall enclosure. The cost of capping this area should be compared with the
estimated savings from treating the reduced amount of extracted water. Therefore, the
decision to cap the northern portion of the site should likely be delayed until the P&T
system has been operated for a few years and a more accurate estimate of the cost
savings from reduced pumping can be determined. Capping could actually be
counterproductive to eventual cleanup of the site due to the lack of flushing and the
inability of aerobic water to infiltrate through the capped area. The cap provides no
extra protectiveness if hydraulic containment is maintained and the site is secure.
2.4 CONSIDER THE POTENTIAL FOR ON-SITE REGENERATION OF VAPOR PHASE GAC
The O&M costs include an estimated cost of $140,000 per year for the vapor phase
GAC that would be used to treat the air stripper off-gas. This estimate is consistent
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with GAC usage and unit costs estimated by the evaluation team. With an extraction
rate of 60 gpm and a total VOC influent of approximately 75,000 ug/L (based on
reported estimated average influent concentrations), the mass loading to the air stripper
will be approximately 20,000 pounds of VOCs per year. Based on air stripper
modeling for Northeast Environmental Products (NEEP) tray aerators, the offgas
concentration would likely be on the order of 100 ppmv. The estimated GAC usage for
benzene and related compounds at this concentration is approximately 4 pounds of
GAC per pound of contaminant. Therefore, the estimated GAC usage may be as high
as 80,000 pounds per year. At a cost of approximately $1.75 per pound, this would
translate to costs of approximately $140,000 per year for vapor phase GAC.
Although influent concentrations may decrease over time, the decrease is likely to be
quite small due to the presence of NAPL and the limited amount of clean water
entering the area enclosed by the barrier wall. Also, although the site team anticipates
reducing the extraction rate to 30 gpm after a few years of operation, the required
extraction rate may be higher than expected due to minor inconsistencies in the barrier
wall construction or higher than expected water from the underlying Potomac Aquifer.
Any pumping from contaminated areas outside of the barrier wall would also increase
the overall mass loading and therefore the vapor phase GAC usage.
Based on the above information, it appears that the vapor phase GAC costs may be
higher than expected, and it may be more cost-effective to regenerate the vapor phase
GAC on site. The Savage Municipal Well Fund-lead site uses on-site vapor phase
GAC regeneration, and this approach may also work for the Standard Chlorine of
Delaware site. The system would require operation and maintenance of a boiler to
generate steam for the GAC regeneration. The recovered product would be stored and
later disposed of offsite at an appropriate facility.
It is recommended that the site team investigate the cost-benefit of on-site vapor phase
GAC regeneration. Savings would be realized from eliminating an estimated $140,000
in GAC replacements, but costs would be incurred for purchasing the regeneration
system, operating and maintaining the boiler (which may be high if additional labor is
required), and disposing of the recovered contamination. If preliminary cost estimates
done during design do not suggest substantial savings, it may be most appropriate to
proceed with off-site regeneration and re-evaluate GAC usage during actual P&T
operation before investing in an on-site regeneration system.
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Cost Summary Table
Recommendation
2. 1 Further Investigate the Presence of
Contamination in the Potomac Aquifer
2.2 Compare Anticipated Full-Scale Costs
of Chemical Oxidation for Downgradient
Plume with the Costs of Additional
Extraction in the Same Area
2.3 Reevaluate Costs of Capping Northern
Area of Site to Limit Infiltration and
Reduce Extraction Rate
2.4 Consider the Potential for On-Site
Regeneration of Vapor Phase GAC
Estimated Capital Cost
$75,000
$0
$0
$0
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