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July 11, 2002
Via E-mail
Mr. Kirk Coulter
Texas Natural Resource Conservation Commission
Industrial and Hazardous Waste Section
P.O. Box 13087 (MC148)
Austin, TX 78711-3087
Subject: Management of Drilling Materials Generated During
RFI Activities at Camp Stanley Storage Activity, Texas,
SWR # 69026, EPA ID # TX2210020139
Dear
Mr. Coulter,
This
letter is a response to regulatory meeting held on March 5, 2002 regarding Camp
Stanley Storage Activity’s (CSSA) – Texas Pollutant Discharge Elimination
System (TPDES) Permit. The meeting was
held between representatives from the TNRCC, U.S. EPA, CSSA, and Parsons. Discussions regarding the management of Investigative-Derived
Waste (IDW) anticipated from upcoming drilling projects led to a request from
TNRCC to propose a management methodology for review and approval. This letter
presents options for IDW handling that Parsons believes is protective of the
human health and the environment and meets our criteria for management of the expected
IDW. CSSA anticipates a timely review
to prevent further delays in its’ investigation activities.
For
further discussions, Parsons defines the term “contaminated media” to include
all media above health-base standards (i.e., above State of Texas Risk
Reduction Program (TRRP) Tier 1 Protective Concentration Levels (PCLs) and Safe
Drinking Water Act (SDWA) maximum contaminant levels (MCLs). As such, discharge of non-contaminated media
that are below federal and State health-based standards back to the ground
surface requires no further treatment or permitting efforts. In a letter penned by L’Oreal Stepney of the
TNRCC Wastewater Permitting Section on March 5, 2002, “the TNRCC Wastewater Permitting Section concurs with your position
that groundwater determined to be uncontaminated prior to treatment does not
require authorization under the TPDES program provided the groundwater quality
will not cause pollution of any of the water in the state as stated by Section
26.121 of the Texas Water Code.” The
following paragraphs provide details regarding the proposed handling
methodologies of the IDW media.
CSSA
is located in Boerne, Texas and is currently under an EPA 3008(h) Consent Order
to perform investigative and corrective action activities under RCRA with
respect to contamination resulting from past operational practices. In addition to RFIs and other ongoing
environmental investigations, CSSA has been undertaking a large-scale
groundwater investigation and monitoring program to define the vertical and lateral
extent of solvent plumes impacting the Middle Trinity aquifer that serves
municipal and domestic consumers in the vicinity of the installation. Recent data suggest that the plume has moved
beyond the boundaries of the installation, and has impacted off-post drinking
water wells. The need for hydrologic
characterization and plume delineation as soon as possible is the greatest
priority to CSSA.
To
this end, CSSA has been aggressively implementing a groundwater monitoring
program to address these issues in compliance with the EPA 3008(h) Consent
Order. We have recently completed Phase
I of this investigation, which included the installation of 15 new groundwater
monitoring wells. The Phase I wells
took nearly a year to fully implement, and encountered many challenges
including the handling of copious quantities of drilling material generated
during their installation.
For
Phase II, CSSA proposes to implement an approach for investigation-derived
media management that is protective of human health and the environment. This letter presents a discussion of the
proposed management of these potentially contaminated media.
Drilling methodology
The
following is intended to give the reader a sense of the scale at which volumes
of groundwater and soil cuttings are produced.
This section will provide process knowledge of how CSSA installs and
manages drill cuttings and produced groundwater (media).
Up
to 25 monitoring wells are scheduled to be installed in the Middle Trinity
aquifer underlying CSSA. The three
hydrologic units of interest are the Lower Glen Rose (LGR) Limestone, the Bexar
Shale (BS), and the Cow Creek (CC) Limestone.
The actual drilling depth will be a function of each well location and
land surface elevation. In general,
wells ranging between 120 to 580 feet below ground surface are to be installed
during the Phase II drilling operation.
The end product will be approximately 25 wells with a nominal four inch
diameter casing and maximum screen length of 25 feet. Depending on the hydrologic zone of interest, different well
designs will be implemented to ensure the integrity of each monitoring
point. Table 1 shows the total
estimated depth for each of the Phase II wells to be installed.
Drilling
to depths up to 500 feet produces significant amounts of drill cuttings (soil
and limestone) as well as groundwater.
It is estimated that as much as 165 cubic feet (6 cubic yards) of
soil drill cuttings have been generated from a single well. In addition, the relatively slow advance of
the drill bit in relation to the pumping action inherent with the air rotary
drilling methodology generates a large volume of extracted groundwater when
drilling below the water table. As much
as 24,000 gallons of groundwater have been produced during the course of drilling
a single well.
expected quantities to be
generated
Because
of the previous experience of the Phase I drilling project, CSSA has estimated
the amount of total solids and liquids that will be generated from the Phase II
drilling as it is currently scoped. We
anticipate approximately 100 cubic yards of solids (drill cuttings) and between
300,000 to 400,000 gallons of drilling water (i.e., potable injection water
plus groundwater) to be generated during the well installation activities. As much as 100,000 additional gallons of
groundwater will be generated during the development phase. As shown on Table 2, approximately 2,300
cubic yards (nearly 115 roll-off containers or 450,000 gallons) of drilling
material (i.e., mud and groundwater) are expected to be generated over the
14-month drilling schedule.
proposed Handling of drilling
materials
As
indicated, CSSA anticipates generating nearly 450,000 gallons of drilling
materials during the Phase II well installation. Adequate storage capacity will be required to effectively handle
the media. The proposed option will use
a settling basin located near CSSA’s outfall 002. Parsons believes the settling basin methodology is deemed to be a
more economical and appropriate method of handling the generated drilling
materials while continuing to be protective of human health and the
environment.
At
this time, Parsons is proposing to utilize a single settling basin located near
the TPDES-permitted 002 outfall in the central portion of the base. The settling basin will be accompanied by a
infiltration basin for the controlled release of uncontaminated water back to
the environment. The proposed site is
located within the inner cantonment area at SWMU B-10.
SWMU
B-10 is located 800 feet south of Well 16 and the CSSA groundwater treatment
unit. (Figure 1). The site has an
area of approximately 17,400 square feet (0.4 acres). SWMU B-10 was reportedly used as an ammunition disposal area. However, subsequent investigation and waste
removal actions found no ammunition or unexploded ordinance. Waste removed from the site consisted of
banding material and ammo cans. Prior
to excavation, the SWMU B-10 site was covered with native grasses. Trees are along the western boundary and a
dirt road is located directly to the east.
Trees identified at the site included mountain juniper and oaks. After waste removal actions the area was
backfilled with dense clay-rich soil which provides the underlying material for
the proposed settling basin.
The
following items address concerns, expressed by the TNRCC in a memorandum and
its’ attachments from the Industrial and Hazardous Waste Section on 5 March
2002, regarding the implementation of the settling basins. Parsons has tried to address these concerns
with regard to the current plan and proposed siting location.
1. Specify if any of the settling basin(s)
will be located within the 100-year flood plain, If within the flood plain, provide flood prevention measures
The
proposed location is not within the 100-year floodplain as given on FEMA flood
hazard maps.
2.
Describe
the construction of the settling basin
CSSA
proposes to utilize a lined settling basin for containment and will have bermed
sides with sufficient freeboard to prevent stormwater run-on and designed to
contain precipitation from storm events.
The settling basin would use the clay-rich soil backfilled with SWMU
B-10 as an underlying layer to a 60 mil High Density Polyethylene (HDPE)
flexible membrane liner. The underlying
layer will contain at least 1 foot of compacted clay-rich soil material along
the sides and bottom of the basin intended to achieve the lowest permeability
practical given the properties of the imported
materials. The 60 mil HDPE liner would
overlay the compacted clay soils. An
access ramp will also be constructed for the offloading of liquid and solid
media. Fencing will surround the
settling basin in order to minimize potential exposure to wildlife and
livestock.
3. Identify how each phase (liquid and
solid) of the IDW will be transported from the point of generation to the
settling basin, GAC unit, wastewater treatment facility, and/or final
disposition location
All generated drilling materials will be taken to the basin
via vacuum truck or other applicable transportation methods. The bulk of the material will be transported
by vacuum truck as the drilling fluids are produced by the drilling
subcontractor.
Multiple transportable 20 to 30-yard roll-off boxes will
also be placed at each well to contain media to allow for proper
characterization. Wells which may
generate “contaminated” media are MW16-CC, MW13-LGR, MW14-LGR, MW1-BS, MW1-CC,
and MW2-CC. During the installation of
these wells IDW will be collected and sampled before placement into the
settling basin. If analytical results
indicate that the IDW is contaminated the material will be transported to the
TPDES Outfall 002 treatment system where the liquid fraction will be treated
and discharged in accordance with permit requirement. If however, the analytical results indicated that the generated
IDW is found not to be contaminated, the material will be transported and
managed with the settling basin.
4. Provide the rationale for using the GAC
unit prior to the waste water treatment facility
The proposed settling basin is to be sited near the outfall
002 GWTP. Groundwater that does not
meet clean water discharge criteria will be pumped directly from the storage
container or the settling basin to the GWTP for treatment by granular activated
carbon prior to discharge to outfall 002 as authorized by CSSA’s TPDES
permit. The GWTP effectively removes
organic contaminants from the waste stream well below the permitted discharge
limits at an operational capacity of 10 to 20 gallons per minute (gpm). With this plan, the WWTP located at outfall
001 will not be utilized in this program.
5. Describe the process to be used for waste
classification
Periodically, sampling of the drilling materials within the
basin will occur in order to identify appropriate management methods for the
contained materials. The liquid fraction,
which has analytical results greater than TRRP Tier 1 PCLs for CSSA’s COCs,
would be routed through the GAC unit at CSSA’s Outfall 002. The solid fraction that has analytical
results above TRRP Tier 1 PCLs for CSSA’s COCs would be managed in an appropriate
off-site landfill. If analysis of the
materials indicates that the COCs are below the health based standards (i.e.,
TRRP Tier 1 PCLs) they would be discharged to the ground surface.
6. Demonstrate current permit discharge
limits will not be exceeded
CSSA is authorized to treat and dispose of wastes by TPDES
permit no. 03849. The permit allows for
the discharge of treated effluent waste water from two outfalls (001 and
002). For this discussion, only outfall
002 is being considered for potential treatment of contaminated media. Permit limits associated with outfall 002
include treatment and release of wastewater at a daily average rate of 30,000
gallons/day and a daily maximum of 60,000 gallons/day. The maximum capacity of the current GWTP is
28,800 gallons per day. Effluent
characteristics specified by the TPDES permit indicates discharge limits for
daily average of PCE and TCE at 36 ppb and a daily maximum at 77 ppb. Parsons believes, based on our previous
experience during the Phase I well installation efforts, that all TPDES permit
requirements will be met. Use of a
settling basin will allow sufficient volume of contaminated media to be held in
the event recovered media are contaminated and require treatment.
7. Describe the waste management practices
for the settling basin, including the length of time for settling purposes and
sludge removal techniques
Periodically, sampling of the drilling materials within the
basin will occur in order to identify appropriate management methods for the
contained materials. Parsons
anticipates sampling of the media held in the basin to occur after the
turbidity of the liquid fraction is less than or equal to 50 nephelometric
turbidity units (NTU), or at most a monthly basis. The NTU standard will be checked on a weekly basis. When the media meets the 50 NTU standard it
will be appropriate for introduction into the GWTP. The solid fraction held within the settling basin will be characterized
and removed, if necessary, upon completion of the Phase II drilling efforts.
8. Closure of settling basin upon completion
If the settling basin has been found to contain
“contaminated media” the settling basin will become apart of TPDES permit no.
03849. The settling basin will be used
for future investigation efforts anticipated for the facility. Upon completion of the RFI activities,
closure samples will be taken from underneath the former settling basin
location and analyzed for COC’s in order for determinations to be made regarding
proper closure criteria as specified in TRRP.
If however, no “contaminated media” was found to have been managed
within the settling basin no closure efforts are required and future use is not
limited to TPDES requirements.
In summary, the proposed use of settling basin will allow
efficient and expedient investigation of groundwater to define the vertical and
lateral extent of solvent plumes impacting the Middle Trinity aquifer that
serves municipal as well as domestic consumers in the vicinity of the
installation. Ultimately, the use of
the basin will allow a more rapid response to impacted waters and citizens of
the State.
Please
call me (512) 719-6087 or Ken Rice (512) 719‑6050 if you have any
questions about the options for IDW management identified for the Phase II
groundwater monitoring well installation efforts.
Sincerely,
Scott
Pearson
Task Manager
Attachments
cc: Brian Murphy, CSSA
Greg Lyssy, CSSA
Henry Karnei, TNRCC-Region 13
Craig Meppen, TNRCC-Region 13
Abigail Power, TNRCC-Region 13
Jorge Salazar, TNRCC-Region 13
David Galindo, TNRCC-Austin
Phyllis Primrose, TNRCC-Austin
Karuna Mirchandani, Parsons
Ken Rice, Parsons
740911 Project File