HomeMy WebLinkAboutXenon report 9-11-2013
Evaluation of the potential environmental impacts to
ground water quality which could result from the
future operation of a retail gas station
at the southwestern corner of
1 46th Street and River Road
City of Carmel, Indiana
September 11, 2013
Prepared for:
Mr. John Duffy
Director of Utilities
City of Carmel
One Civic Square
Carmel, Indiana 46032
Prepared by:
Xenon Geosciences, Inc.
95 N Tennessee Street
P.O. Box 681
Danville, Indiana, 46122
Evaluation of the potential environmental impacts to ground water quality Page ii of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
Contents
1 Purpose.............................................................................................................................................. 1
2 Introduction ....................................................................................................................................... 1
3 Evaluation Criteria .............................................................................................................................. 2
4 Applicable Laws and Regulations ........................................................................................................ 2
4.1 UST system installation ..........................................................................................................................2
4.2 UST operator training .............................................................................................................................3
4.3 Release detection ...................................................................................................................................3
4.4 Reporting ................................................................................................................................................5
4.5 Spills........................................................................................................................................................6
4.5.1 Surface spills related to the operation of a UST system ................................................................6
4.5.2 Spills unrelated to the UST system ................................................................................................6
4.6 Storm water permitting..........................................................................................................................6
4.6.1 Storm water permit for construction activity ................................................................................7
4.6.2 Storm water permit for industrial activity .....................................................................................7
4.6.3 Storm water permit for MS4s (Rule 13) ........................................................................................7
4.7 Community Right-To Know Act ..............................................................................................................7
5 Site Conditions ................................................................................................................................... 8
5.1 Geologic setting ......................................................................................................................................8
5.2 Aquifer characteristics ...........................................................................................................................8
5.2.1 Variations in ground water elevation ............................................................................................9
5.2.2 Variations in ground water flow ....................................................................................................9
5.3 Well use ............................................................................................................................................... 10
5.4 Surface water setting .......................................................................................................................... 11
6 Gas Station Operations ..................................................................................................................... 11
6.1 Release detection from UST systems .................................................................................................. 11
6.1.1 Use of observation wells for release detection .......................................................................... 12
6.2 Containment of releases and spills ..................................................................................................... 12
6.2.1 Subsurface release containment ................................................................................................ 12
6.2.2 Hydraulic containment (pumping) .............................................................................................. 14
6.2.1 Surface spill containment ........................................................................................................... 15
6.3 Treatment systems .............................................................................................................................. 15
6.3.1 Ground water treatment ............................................................................................................ 17
6.3.2 Surface water treatment ............................................................................................................ 17
6.3.3 Compatibility of storm water BMPs with petroleum fuels ......................................................... 19
6.4 Ethanol and other regulation-driven additives ................................................................................... 19
6.4.1 Known incompatibility with UST system components ............................................................... 19
6.4.2 Future oxygenates ...................................................................................................................... 21
6.5 UST system maintenance .................................................................................................................... 21
6.6 UST system upgrades .......................................................................................................................... 21
6.7 Maintenance of observation wells and similar structures .................................................................. 22
6.8 Operator training ................................................................................................................................ 22
6.9 Ground Water Protection Plan (GWPP) .............................................................................................. 23
6.9.1 Storm water pollution prevention .............................................................................................. 23
6.9.2 Spill prevention and response .................................................................................................... 23
6.9.3 Site maintenance and operations ............................................................................................... 24
7 Release Scenarios ............................................................................................................................. 25
Evaluation of the potential environmental impacts to ground water quality Page iii of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
7.1.1 Sudden, large-volume releases ................................................................................................... 25
8 Environmental Impacts ..................................................................................................................... 27
8.1 Aquifer vulnerability ............................................................................................................................ 27
8.1.1 Presence of contamination sources ........................................................................................... 28
8.1.2 Hydrogeological conditions ........................................................................................................ 28
8.1.3 Contaminants released to ground water and surface water...................................................... 29
8.2 Human & environmental exposure ..................................................................................................... 30
9 Discussion of Findings ....................................................................................................................... 31
9.1 The aquifer is vulnerable to contamination ........................................................................................ 31
9.1.1 Limitations of storm water regulations ...................................................................................... 34
9.1.2 Limitations of spill reporting, containment and response ......................................................... 34
9.2 Protections must be built in from the start ........................................................................................ 34
9.3 Future use of fuel additives may result in releases ............................................................................. 35
9.4 Do not assume contaminant plumes will extend only 200 feet ......................................................... 35
9.5 Expect cleanup of the aquifer to be slow and difficult ....................................................................... 35
10 Recommendations ........................................................................................................................... 35
11 References ....................................................................................................................................... 39
INDEX OF TABLES
Table 4-1: Summary of release detection methods that can be applied for underground storage tanks located
within wellhead protection areas (329 IAC Rule 9) ................................................................................... 4
Table 4-2: Summary of corrective actions to releases of petroleum from UST systems (329 IAC Rule 4) .................... 5
Table 5-1: Vertical geological profile at the Legacy site as determined from available site data. ................................. 8
Table 5-2: Summary of published characteristics of the White River and Tributaries Outwash Aquifer System. ......... 9
Table 5-3: Summary of time-of-travel boundaries which encompass the subject property. ...................................... 10
Table 6-1: Summary of selected subsurface containment options .............................................................................. 16
Table 7-1: Release scenario matrix .............................................................................................................................. 26
INDEX OF FIGURES
Figure 1: Conceptual drawing of an underground vault. ............................................................................................. 13
Figure 2: Number of entries in IDEM LUST report that occurred in wellhead protection areas ................................. 26
Figure 3: Summary of plume lengths from various studies. ........................................................................................ 33
Evaluation of the potential environmental impacts to ground water quality Page 1 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
1 PURPOSE
This objective of this report is to evaluate the potential environmental impacts to ground water quality which could
result from the future operation of a retail gas station at the southwestern corner of 146th Street and River Road
(herein referenced as the "subject property.") Although it was prepared at the time of a development proposal for a
service station by Ricker Oil Company, this report is not intended to address specific elements which have been
submitted on Ricker's behalf. Instead, this report should apply to any proposal for the operation of a retail gasoline
station, and by extension, other development that would involve the handling of petroleum or similar products that
could contaminate the ground water resources beneath the subject property. This purpose of this report is to be a
technical reference for the City of Carmel Utilities and for those parties interested in developing at this location. It is
to serve as a guide to the issues that must be addressed by a developer before the City of Carmel Utilities will
consider the development proposal to be adequate and complete.
2 INTRODUCTION
This report evaluates aspects of the possible operation of a future service station at the subject property that could
affect the underlying ground water resources or its users. The subject property overlies prolific and vulnerable
ground water resources that are in use as potable water supplies. We believe that the value of this aquifer will
increase with time as adequate ground water resources become scarcer. Today, residential drinking water wells are
located immediately north of the subject property and several municipal wells are operated nearby. Indeed, the
subject property lies within the one-year travel time boundary of wells operated by Citizen's Energy Group.
The USGS considers the vulnerability of ground water resources to be dependent on three environmental factors: (1)
the presence of contaminant sources, (2) the combination of physical and chemical processes in the subsurface
which affect contaminant concentrations in an aquifer; and (3) the ease with which water and contaminants can
travel to and through an aquifer [Eberts et al., 2013].
Factor (1) is the only one of the three that does not exist at the subject property today. While the construction of a
gas station does not create a contaminant source per se, the delivery, storage and dispensing of petroleum fuels
present significant risks. Low-volume but frequent spills of petroleum to the ground surface are certain during the
daily operations. A smaller but more significant risk lies with the development of leaks from the underground
storage tank (UST) system. Perhaps the lowest probability but most significant in scale is the catastrophic release of
thousands of gallons of fuel, either above-ground or below-ground.
The last two of the three environmental factors are already established. Factor (2) refers to characteristics of the
aquifer system such as the distribution of permeable versus impermeable sediments or the presence of indigenous
microorganisms that can digest petroleum compounds and thereby diminish the contaminant concentrations. Factor
(3) refers to the ability of chemicals that are spilled onto the ground surface or into the shallow subsurface to reach
the ground water within the aquifer. This factor would include the presence or absence of an impermeable clay layer
that would act as a barrier to the infiltration of spilled contaminants to the aquifer.
Therefore, the absence of a gas station (or any other facility that stores and handles products that could
contaminate ground water) is the most protective measure available
If it is assumed that a gas station will be constructed on the subject property, then the risks involved with the three
factors identified by the USGS can only be mitigated by degrees. It is not possible to both have an operating gas
station and have a risk equivalent to the absence of a gas station. Instead, the risks would be addressed by engineered
structures and operational practices. Under this scenario, it will be of paramount importance that all engineered and
operational aspects which are deemed necessary to achieve an acceptable level of risk are maintained over the
.
Evaluation of the potential environmental impacts to ground water quality Page 2 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
lifespan of the facility operations
In evaluating the potential impacts of a gas station, this report considers design elements that have been presented to
the City of Carmel; applicable laws and regulations; site conditions such as the hydrogeologic setting and usage of
ground water resources; and potential sources and release scenarios of contamination. We present our conclusions
and recommendations.
3 EVALUATION CRITERIA
These primary components that are evaluated in this report consist of the following items:
1. The three factors that have been identified as contributing to aquifer vulnerability;
2. Applicable laws and regulations governing the installation and operation of the UST system, employee
training, responses to releases from the UST system, and surface spill response (Section 4 );
3. Site conditions, including the physical and chemical nature of the aquifer beneath the subject property and
the use of the ground water it contains for potable water supplies (Section 5 );
4. The proposed operations at a gas station, including routine operations, UST systems, the potentials for
routine and catastrophic spills to the ground surface, the collection, conveyance, and treatment of storm
water, emergency response procedures and operator training (Section 4.2 ); and
5. Potential environmental impacts resulting from releases to the surface and subsurface (Section 6).
In performing this evaluation, Xenon has reviewed design documents prepared on the behalf of Turkey Hill Minit
Markets [DZE, 2010; Stoppelwerth, 2010a; WCC, 2010; Weihe, 2010], a report and design documents prepared on
behalf of Ricker Oil Company [Creek Run, 2013; Weihe, 2013], remonstrance documents prepared by Citizens
Energy Group [CEG, 2013], and various other technical sources as presented throughout this report.
4 APPLICABLE LAWS AND REGULATIONS
The installation and operation of underground storage tank systems are regulated by the U.S. EPA1
Note that this report distinguishes between releases of petroleum products which unintentionally escape directly to
the subsurface as a result of leaks or damage a UST system, and spills of materials onto the ground surface, surface
water or objects. For example, spills would relate to gasoline splashed onto the ground by customers or fuel truck
operators.
and delegated to
the state of Indiana. Indiana established its UST program by statute (IC-13-11) and developed regulations for UST
systems under Indiana Administrative Code (329 IAC 9).
4.1 UST SYSTEM INSTALLATION
The Indiana Department of Environmental Management (IDEM) is responsible for assuring that all regulated
underground storage tanks meet the U.S. EPA's and Indiana's requirements for release detection, spill and overflow
prevention, and corrosion protection; and to insure that tanks not meeting those requirements are properly closed or
upgraded. The rules also require that a Department of Fire and Building Safety certified contractor or worker must
be present on-site at all times during the installation, testing, upgrading, closures, removals, or change-in-service of
UST system.
The installation of new UST systems within one-year time-of-travel (TOT) boundaries of a wellhead protection
1 40 CFR 280
Evaluation of the potential environmental impacts to ground water quality Page 3 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
area 2
4.2 UST OPERATOR TRAINING
is regulated under 329 IAC 9-2-1.1. This rule includes provisions for the construction of tanks and piping, the
construction of observation wells, notification requirements, and certification requirements for UST system
installation, testing, upgrades, closures, removals and changes-in-service. Specifically, the regulations require UST
systems within a one-year TOT to utilize double-wall tanks and piping with interstitial monitoring, or to install an
impermeable secondary barrier with wells that are instrumented for release detection.
All of Indiana’s gas stations must designate their employees as Class A, Class B, or Class C operators for various
responsibilities of UST system operations. Class A, Class B, and Class C operators must be certified in various
aspects of system maintenance and operations.
Either a Class A, Class B, or Class C operator must be present on-site during the operation of a UST system facility.
Class C operators may be trained by the Class A or B for the facility or their designee.
Class A operators are persons with primary responsibility for the overall operation of one or more UST systems.
Their responsibilities include managing resources and personnel, such as establishing work assignments, to achieve
and maintain compliance with this article and state and federal laws related to USTs. Class A operators are required
to ensure that personnel properly operate and maintain the UST system, maintain appropriate records, receive
training to operate and maintain the UST system and keep records, respond to emergencies or alarms related to
releases, leaks, or spills from UST systems at the facility and make financial responsibility documents available to
the department as required.
Class B operators have daily on-site responsibility and direct control over the operation, maintenance, and record
keeping for one or more UST systems. Class B operators are responsible for monitoring and ensuring that release or
leak detection equipment and methods, record keeping, and reporting requirements are met, that all relevant
equipment complies with performance standards, that appropriate personnel are trained to properly respond to
emergencies or alarms caused by releases, leaks, or spills from the UST system.
Class C status is for facility employees, like cashiers, who assist Class A and Class B operators in monitoring for
problems and responding to emergencies. Class C operator is an employee or contractor of the UST system facility
who has on-site responsibility to initially respond to alarms or other indications of emergencies caused by spills,
leaks, or releases from UST systems. Class C operators are provided with written instructions that include
procedures for overfill protection during delivery of regulated substances, operation of emergency shut-off systems,
appropriate responses to all alarms, reporting of leaks, spills, and releases, the name and contact information of
persons to contact if a leak, spill, or release occurs, and all site-specific emergency procedures.
4.3 RELEASE DETECTION
Applicable regulations 3
Table 4-1
specify the methods that an owner can use to meet requirements for the detection of
subsurface releases from the UST system. The release detection criteria for tanks are summarized in .
2 The subject property is not within a one-year TOT for existing City of Carmel wells. It is within the one-year TOT for wells operated
by Citizens Energy Group located outside of Carmel. See Section 5.3 .for details. 3 329 IAC 9-7-4
Evaluation of the potential environmental impacts to ground water quality Page 4 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
Table 4-1: Summary of release detection methods that can be applied for underground storage tanks
located within wellhead protection areas (329 IAC Rule 9)
Method Detection requirements Comments
Product inventory control Detect a release of at least 1.0% of flow-
through plus 130 gallons/month.
A 125 gallon/month release could go
unreported.
Manual tank gauging Varies by tank capacity, cannot be applied
for tanks exceeding 2,000-gallon capacity.
Not expected to apply to subject property.
Tank tightness testing Detect a 0.1 gallon/hour leak. A 70 gallon/month release could go
undetected.
Automatic tank gauging Detect a 0.2 gallon/hour leak. A 140 gallon/month release could go
undetected.
Soil gas sampling No quantitative requirements established. No estimate of the release volume that could
go undetected.
Interstitial monitoring No quantitative requirements established. No estimate of the release volume that could
go undetected.
Any other method, or
combination of methods one
of the following is completed:
Detect 0.2 gallon/hour leak
A 70 gallon/month release could go
undetected.
Probability of detection of 0.95 and a
probability of false alarm of 0.05.
No estimate of the release volume that could
go undetected.
The method is third party certified. No estimate of the release volume that could
go undetected.
Piping detection
Automatic line leak detectors that alert the
operator to the presence of a leak by
restricting or shutting off the flow of
regulated substances through piping or by
triggering an audible or visual alarm.
3 gallons/hour at 10 pounds/inch2 of
line pressure within one hour.
A 2,000-gallon/month release could
go undetected.
Periodic line tightness testing. Detect a 0.1 gallon/hour leak rate at 1.5
times the operating pressure.
A 70 gallon/month release could go
undetected.
Applicable tank methods if the methods are
designed to detect a release from any
portion of the underground piping that
routinely contains regulated substance
a. Test or monitor for vapors in the
soil gas;
b. Detectable by monitoring devices
located in the UST excavation
zone;
c. Testing or monitoring for liquids
on the ground water;
d. Interstitial monitoring between the
UST system and a secondary
barrier; or
e. Any third-party certified method
capable of detecting a 0.2
gallon/hour leak or a 50- gallon
release within a month, and with a
probability of detection of 0.95
and a probability of false alarm of
0.05.
No estimate of the release volume
that could go undetected.
Evaluation of the potential environmental impacts to ground water quality Page 5 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
4.4 REPORTING
Releases from UST systems are regulated under 319 IAC 9-4. This regulation establishes a specific course of action
in response to confirmed releases from UST systems which are intended to identify and mitigate immediately
hazardous conditions, to characterize the nature and extent of contamination, identify potential human and
environmental exposures to the contaminants, and identify corrective actions to mitigate those exposures. Though
the process is thorough, it can take significant time to complete, as summarized in Table 4-2.
Table 4-2: Summary of corrective actions to releases of petroleum from UST systems (329 IAC
Rule 4)
Elapsed time Event
0 hours Release occurs
24 hours Notification to IDEM
7 days Investigate and confirm release. This can include tightness testing of the UST system.
If subsurface sampling of soils and ground water indicates that no contaminants are
present, then no additional action is required.
If contaminants are detected...
24 hours
20 days
Stop the release, drawdown fuel from the system to minimize release, mitigate
hazards. Monitor sewers, buried utilities, houses with basements or crawl spaces.
Subsurface sampling of soils and ground water in areas where contamination is most
likely to exist.
Report to IDEM
60-67 days Initial Site Characterization - this includes research on site conditions,
characterization of the contaminant release and hydrogeologic conditions,
identification of possible exposures and other details. Soil and ground water samples
are analyzed buy a laboratory. Report due to IDEM within 60 days.
If free product(1) is detected...
45-52 days Initiate free product removal to the maximum extent practical as determined by IDEM
based on free product removal technology and site conditions.
If information is incomplete, wells have been affected, free product
requires recovery, evidence that contaminated soils are in contact
with ground water, or as IDEM requests...
Unspecified Further Site Characterization - this includes additional research on site conditions,
characterization of the contaminant release and hydrogeologic conditions,
identification of possible exposures and other details. Soil and ground water samples
are analyzed buy a laboratory. Report due to IDEM within 60 days.
As IDEM directs...
Unspecified Corrective Action Plan - A corrective action plan contains a plan for the remediation
of released contaminants to levels that are appropriate for the contaminant released
and their potential exposures to people and the environment.
1. Free product is liquid gasoline, diesel fuel or other petroleum products that are not dissolved in the ground water.
Evaluation of the potential environmental impacts to ground water quality Page 6 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
4.5 SPILLS
If the subject property is utilized as a retail gasoline service station, it is unlikely to be required to complete a Spill
Prevention, Control, and Countermeasure (SPCC) Plan under 40 CFR 112. The underground storage tanks are
exempt from the rule as long as the total storage capacity is less than 42,000 gallons. Above-ground bulk storage
containers or oil-filled operational equipment that has a capacity of less than 55 gallons are also exempt. However,
an SPCC plan would be required if automotive repair services are provided at the facility and above-ground
petroleum storage exceeds 1,320 gallons.
There are separate regulations regarding spills from UST systems (i.e., spills by a tanker truck operator) and spills to
the ground surface during construction or other operational activities.
4.5.1 Surface spills related to the operation of a UST system
Surface spills and overflows from UST systems are regulated under 329 IAC 9-4. Any contaminated media resulting
from a spill must be contained and immediately removed. The Rule requires sets a 25-gallon spill threshold before
the spill must be reported to IDEM. (The loss of petroleum due to below-ground leaks from the UST system are
regulated separately as described in Section 4.3).
4.5.2 Spills unrelated to the UST system
Spill reporting, containment and response rules4 determine the requirements to report, contain, and respond to spills
of hazardous substances, extremely hazardous substances, petroleum, and objectionable substances 5 that are of a
quantity, type, duration and in a location as to damage the waters of the state 6
The spill rules identify particular Special Areas on the basis of their unique geology which increases their
susceptibility to contamination from spills. [Although the rule has a listing of specific areas that does not include
areas in the vicinity of the City of Carmel, the hydrogeological conditions at the subject property are vulnerable to
spills as discussed in Section
.
8.1 .]
The rule7
a. spills of hazardous substances or extremely hazardous substances when the amount spilled exceeds one
hundred (100) pounds or the reportable quantity, whichever is less;
addresses the requirements to report spills of petroleum and hazardous materials and sets threshold
quantities above which the spill reporting requirements apply. For areas within wellhead protection areas, the
reportable quantities are as follows:
b. spills of petroleum when the amount spilled exceeds fifty-five (55) gallons; or
c. spills of objectionable substances (defined as a quantity and a type; and present for a duration and in a
location; so as to damage waters of the state. This definition excludes hazardous substances, extremely
hazardous substances, petroleum, and mixtures thereof.
4.6 STORM WATER PERMITTING
The Indiana Department of Environmental Management has regulatory authority for the implementation of the
National Pollutant Discharge Elimination System (NPDES) permits as mandated by the Clean Water Act and
4 327 IAC 2-6 5 Objectionable substances means substances that are (a) of a quantity and a type; and (b) present for a duration and in a location; so as
to damage waters of the state. This definition excludes hazardous substances, extremely hazardous substances, petroleum, and
mixtures thereof. 6 Waters of the state means "... water, surface and underground, natural and artificial, public and private." [IC 13-11-2-265] 7 327 IAC 2-6.1.5
Evaluation of the potential environmental impacts to ground water quality Page 7 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
administrated by U.S. EPA. There are three categories of storm water permits that would apply to the construction
and operation of a commercial facility: construction permits (Rule 5), industrial permits (Rule 6), and permits for
municipal separate storm sewer system conveyances (MS4s) (Rule 13).
4.6.1 Storm water permit for construction activity
Rule 5 of 327 IAC 15 requires that the facility obtain a storm water permit for construction activities that will disturb
over 1 acre of land. This permit requires the development of a Storm Water Pollution Prevention Plan (SWPPP)
which includes the following (among many other components):
a. "A description of potential pollutant sources associated with the construction activities, that may reasonably
be expected to add a significant amount of pollutants to storm water discharges." Xenon notes that the
"expected to add a significant amount of pollutants to storm water" criterion does not provide protection
from potential pollutants for spills that infiltrate the ground surface and potentially impact ground water.
b. Material handling and storage requirements.
c. Locations where storm water may be discharged directly into ground water. A note must be added if none
exists.
d. A drainage plan showing locations of points where storm water will leave the project site.
e. Location, size and dimensions of features including permanent retention basin.
4.6.2 Storm water permit for industrial activity
Rule 6 of 327 IAC 15 applies to the operation of industrial facilities (as opposed to municipal sewer systems).
However, the rule 8
4.6.3 Storm water permit for MS4s (Rule 13)
explicitly states that "... automotive service stations, convenience stores, and marinas, are not
required to comply with this rule." Therefore, the operation of a service station would not be regulated under the
NPDES permit rules following the termination of the construction storm water permit.
Rule 13 of 327 IAC 15 establishes requirements for discharges from MS4 conveyances so that public health, existing
water uses, and aquatic biota are protected. This rule requires the City of Carmel to develop a Storm Water Quality
Management Plan that addresses discharges of post-construction storm water run-off from new development areas
that disturb one or more acres of land, or disturbances of less than one acre of land that are part of a larger common
plan of development. Specific items that uniquely apply to the development of a gas station within a wellhead
protection area include:
1. "Infiltration practices will not be allowed in wellhead protection areas, and
2. "New retail gasoline outlets... shall be required... to design and install appropriate practices to reduce lead,
copper, zinc, and polyaromatic hydrocarbons in storm water run-off."
4.7 COMMUNITY RIGHT-TO KNOW ACT
A retail gas station facility is not likely to be required to report under EPCRA 9
8 327 IAC 15-6-2
as determined by the total amount of
underground storage of various petroleum products. The threshold level is 75,000 gallons for gasoline (combined
volume of all grades) and 100,000 gallons for diesel fuel. These criteria apply if the tanks are stored entirely
9 Emergency Planning and Community Right-to-Know Act Hazardous Chemical Storage Reporting Requirements, 40 CFR 370.
Evaluation of the potential environmental impacts to ground water quality Page 8 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
underground and are in compliance with applicable UST regulations at all times during a preceding calendar year.
5 SITE CONDITIONS
Hydrological conditions are a primary evaluation criterion because a release of petroleum to ground water has the
potential to impair tremendous volumes of the drinking water resource that presently supplies residential and
municipal water well owners. To put this into perspective, IDEM suggests that "A spill of only three gallons of
gasoline can spoil drinking water for a small town" [IDEM, 2013a].
5.1 GEOLOGIC SETTING
The surficial geology in the vicinity of Hamilton County, Indiana consists of an extensive till plain with glacial
outwash deposits within the White River valley. The outwash consists of permeable sand and gravel sequences that
are laterally bounded and locally covered by relatively impermeable till plain deposits. Gilles (1976) reported that
the outwash deposits within the Carmel area are approximately 2 miles wide and range from 20 to 120 feet thick.
These glacial deposits are underlain by bedrock.
The outwash generally consists of sediments deposited by meltwater during the retreat of Wisconsinan-age glaciers.
The meltwater contained more sediment than it could carry, and deposited the sediment load as vertically- and
laterally-accreted sequences of well-sorted and coarse-grained sand and gravel [IDNR, 2002]. Only a few clay or silt
lenses have been identified within the outwash deposits, and none has significant horizontal or vertical extent [Gilles,
1976]. The White River floodplain is developed on the surface of the outwash deposits, subjecting the deposits to
modern reworking through erosion and deposition. The unconsolidated outwash materials are underlain by Middle
Devonian limestone and dolomite which has been reported to be reported as being reasonably solid and of low
permeability [Gilles, 1976].
Xenon reviewed boring logs for the subject property that were prepared by others [SEC, 2005; A&W, 2007] as well
as records from the Indiana Department of Natural Resources (IDNR) online water well record database [IDNR,
2013]. These records indicate that the vertical geological profile beneath the site can be summarized in Table 5-1.
Table 5-1: Vertical geological profile at the Legacy site as determined from available site data.
Depth range (feet) Material Source(s)
0.7 - 4.0 Clayey silt to clay SEC, 2005 & A&W, 2007(1)
IDNR, 2013(2) 1.5 - 16.0 Silty sand or clayey sand
4.0 - 120 Mixtures of sand and gravel;
2-ft clay unit at 49 - 51 ft. depth in
one record.
(1) data reported from water well logs at the subject property
(2) data reported from water well logs on the Legacy property only: Numbers 414494 and 414498
5.2 AQUIFER CHARACTERISTICS
The region near the subject property overlies the White River and Tributaries Outwash Aquifer System. This is a
prolific aquifer system with substantial water supply capability, but is highly susceptible to surface contamination in
locations where the outwash materials are at or near the surface and have little or no overlaying clay deposits [Basch,
2013]. Unconfined water table conditions generally prevail in the aquifer system.
Evaluation of the potential environmental impacts to ground water quality Page 9 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
Various studies of the White River and Tributaries Outwash Aquifer System have been performed due to its ability
to yield ample ground water. Wells completed in the aquifer typically yield 10 to 50 gallons/minute whereas high-
capacity wells yield 75 to 2,100 gallons/minute [Scott, 2010]. Table 5-2 summarizes the aquifer properties from a
variety of sources.
Table 5-2: Summary of published characteristics of the White River and Tributaries Outwash
Aquifer System.
Parameter Value Units Source(s)
Saturated thickness 10 - 110 feet Gilles, 1976
Hydraulic conductivity 200 - 267
219
ft/day
ft/day
Geraghty & Miller, 198910
Arihood, 1982
10
Transmissivity 1,000 - 24,000
1,690 - 20,130
23,000 - 32,000
ft2/day
ft2/day
Gilles, 1976
IDNR, 2002
Ortman Drilling, 199310
Storage coefficient 0.11
0.1 - 0.2
0.04 - 0.28
ft/ft
ft/ft
ft/ft
Gilles, 1976
Geraghty & Miller, 198910
Ortman Drilling, 199310
Effective porosity 0.35 - - JHE, 2012
5.2.1 Variations in ground water elevation
The subject property can be expected to experience significant fluctuations in the ground water potentiometric 11
Because the aquifer system has been a reliable and prolific resource for potable water, it has seen increasing
development in recent decades and corresponding declines in ground water reserves. The USGS has operated
observation wells HA-5 and HA-7 (which replaced HA-5), located approximately 1400 feet west of the subject
property. Water levels in HA-5 ranged from approximately 9 to 11 feet below the ground surface from 1987 to 1975
[Gilles, 1976] while levels in HA-7 ranged from approximately 18 to 25.7 feet below the ground surface during 2012
and 2013 [USGS, 2013].
surface due to variations due to two causes. The first is the operation of water production wells, either municipal or
residential. Natural variability in ground water recharge is a second cause of fluctuations of the potentiometric
surface. This can be expected to vary seasonally with the caveat that climatic patterns appear to be trending toward
less frequent but more intense rainfall events [Taylor et al., 2012].
5.2.2 Variations in ground water flow
Gilles [1976] evaluated the ground-water flow in 1974 and concluded that there is a general movement of ground
water out of the till plain, into the aquifer system which ultimately recharged the White River at the stream-aquifer
interface, and that the White River was a gaining stream. However, Gilles' work pre-dated the installation of several
10 in JHE, 2011 11 The potentiometric surface is the height or elevation to which ground water will rise in a well pipe. In an unconfined aquifer, it is
effectively equal to the depth of ground water surface or water table.
Evaluation of the potential environmental impacts to ground water quality Page 10 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
large-capacity municipal supply wells. Well head protection areas (WHPAs) determined by Citizens Energy Group
extend beneath the subject property and to the White River [CEG, 2013]; similar patterns have been observed in
WHPAs for other significant water withdrawal facilities in the area. Xenon believes that this suggests that significant
changes to the ground-water flow regime have occurred and it is likely that ground water beneath the subject
property will flow to the north and northwest towards high-capacity wells instead of toward the White River. This
flow direction could again change with the possible future production from two wells casings 12
5.3 WELL USE
that have been
installed in the Legacy Development.
Currently, there are 11 registered Significant Water Withdrawal Facilities (greater than 100,000 gallons-per-day
capacity) that are completed in this aquifer within a two mile radius of the subject property. These registered
facilities include 24 high capacity wells with a combined withdrawal capability of 23,275 gallons/minute, or
approximately 33.5 million gallons/day. During 2012, nearly 4.3 billion gallons of water were reportedly withdrawn
from the outwash aquifer by these 24 high capacity wells. Fifteen of these wells are owned by Citizens Energy, the
City of Carmel and the Town of Westfield and provide water for public supply. [Basch, 2013]
The subject property is not located within the 1-year or 5-year time -of-travel (TOT) boundaries13
for the City of
Carmel [JHE, 2011] but is within the 1-year travel time boundary for three potable water supply wells that are
operated by Citizens Energy Group (CEG) and located outside of the City of Carmel [CEG, 2013]. The subject
property is reported to be within the 3,000-foot buffer zones that have been established for three water supply wells
Table 5-3: Summary of time-of-travel boundaries which encompass the subject property.
1-year TOT 5-year TOT Source(s)
City of Carmel No(1) No(1) [JHE, 2011]
Citizens Energy Group Yes Yes [CEG, 2013] , [AMEI, 2013]
Residential homes Yes(2) Yes(2) This report(2)
Winding Way Mobile
Home Park
Yes(3) Yes(3) [CEG, 2013]
City of Noblesville Yes Yes [CEG, 2013], [Creek Run, 2013]
Indiana American Water
Company
No Yes [CEG, 2013]
City of Westfield No "is close to" [Cook, 2013]
(1) This assumes that the two wells owned by the City of Carmel which are located on the Legacy property are not
operated. If the wells are operated, the subject property appears very near to both the 1-year and 2-year travel-time
boundaries [JHE, 2011].
(2) See discussion in Section 5.2.2 of this report.
(3) The subject property is within a 3,000-foot radius protection area.
12 IDNR well reference numbers 414494 and 414498.
13 Travel time boundaries, or time-of-travel boundaries, delimit areas within which ground water will be pumped from a well or
wellfield within a specified period of time. For example, all water within a 1-year boundary will be pumped from a well or wellfield
within a one-year period. Travel time boundaries for large-scale pumping (large operators) are commonly determined from numeric
modeling of an aquifer though other methods also exist. While technically the travel time boundaries are three-dimensional in nature,
they are commonly depicted in map view (not in depth).
Evaluation of the potential environmental impacts to ground water quality Page 11 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
for the Graylan Plan and Hamilton Estates trailer parks [AMEI, 2013]. The City of Carmel installed two wells at the
Legacy property that are not presently in operation. If the wells are put into operation, analytical modeling indicates
that the subject property will be very near to, but outside of the 1-year TOT boundary [JHE, 2011] for the wells.
The IndianaMap website [IDNR, 2013] indicates that numerous residential water supply wells are near the subject
property. Four residential wells are within 1,000 feet, and a total of eight are within 2,500 feet of the property. The
nearest residential wells to the subject property are located along the north side of 146th Street. There is no
requirement for residential well owners to delineate travel-time boundaries, so there is no directly-available
information to address whether the wells themselves would pump sufficiently to draw ground water from the subject
property. However, maps of wellhead protection areas for Citizens Energy Group [CEG, 2013] and other public
community public water supply systems suggest that ground water beneath the subject property will flow to the
north and northwest under the influence of these large-capacity supply wells. Consequently, it is likely that ground
water beneath the subject property will likely flow toward the residential wells on the north side of 146th Street.
5.4 SURFACE WATER SETTING
The subject property is located within Region IV of the East Basin the Legacy development, which is being
developed under a storm water master plan. The East Basin incorporates the White River floodplain into the
detention design and conveys storm water eastward towards the White River [Stoppelwerth, 2010b]. The master plan
includes the construction of large-scale BMPs 14
6 GAS STATION OPERATIONS
including wetland areas with a treatment liner [WCC, 2010]. While
portions of the Legacy Development are completed or are presently being developed, the areas immediately
adjoining the subject property are undeveloped and their future use is unknown. In addition, there is presently no
BMP constructed to receive runoff from the subject property. Consequently, the exact routing of storm water
discharges from the subject property is undetermined, though it will most likely be routed to a bioretention pond or
retention basin and then to the Legacy BMP before discharging from the Legacy development.
The operation of a UST system at the subject property introduces a significant risk of contamination of the
underlying ground water resources. The U.S. Environmental Protection Agency (EPA) recognizes that repeated
small releases of petroleum fuels can cause "big environmental problems" [U.S. EPA, 2012].
The release detection criteria for tanks in wellhead protection areas are capable of allowing 70 gallons per month to
leak from a UST system without detection (see Table 4-1). Based on spill rates and volumes estimated for vapor
recovery nozzles [Morgester et al., 1992] and assumed average purchases and volume 15
6.1 RELEASE DETECTION FROM UST SYSTEMS
, approximately 6 gallons of
fuel can be expected to be spilled to the ground surface every month.
Applicable regulations 16
Table 4-1
specify the means that an owner can employ to meet requirements for the detection of
subsurface releases from the UST system. They include the implementation of interstitial monitoring of multi-walled
tanks and piping components, and the use of observation wells installed in areas where secondary containment is
achieved with a constructed liner. Unfortunately, release detection systems that comply with state regulations for
tanks in wellhead protection areas are still capable of allowing 70 gallons per month to leak from a UST system
without detection (see ). In 2008 at the intersection of Main and Guilford in Carmel, a gasket failed on an
14 Best Management Practice - this is a practice or engineered device that is intended to control water pollution and can take the form of
filters, barriers, sorbents, treatment systems, vegetated areas, ponds, basins etc. 15 Xenon assumed an average transaction of 10 gallons/customer and a sales volume of 100,000 gallons/month of product. 16 329 IAC 9-7-4
Evaluation of the potential environmental impacts to ground water quality Page 12 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
underground storage tank and resulted in a release of 8,000 gallons of gasoline before its discovery [CEG, 2013].
6.1.1 Use of observation wells for release detection
New UST systems within a wellhead protection area can employ a single-wall UST if an impermeable barrier is
installed and an observation wells are installed at the lowest point of the UST excavation and down-gradient of the
UST system. The installation of an observation wells down-gradient of the tank basin as a release detection method
is problematic because they will detect only those spills that have already entered the subsurface soils and have
reached ground water.
The use of observation wells within the UST excavation will be limited by the permeable nature of the site soils. The
UST dimensions will require an excavation to a depth that will extend into the sand units that overlie the aquifer
deposits. Therefore, it is possible that small releases from a UST system would soak into the sand without reaching
the observation well screen.
Observation wells at the subject property must be designed with the knowledge that the local hydraulic gradients are
heavily influenced by pumping (see Sections 5.2.1 and 5.2.2
6.2 CONTAINMENT OF RELEASES AND SPILLS
Containment of a spill or release before it can enter the environment has the greatest potential to protect the ground
water resource and the health and welfare of those that rely on it for potable water.
The USGS considers the vulnerability of ground water resources to be dependent on three environmental factors: (1)
the presence of contaminant sources, (2) the combination of physical and chemical processes in the subsurface
which affect contaminant concentrations in an aquifer; and (3) the ease with which water and contaminants can
travel to and through an aquifer [Eberts et al., 2013]. At present, the subject property does not pose a risk to the
aquifer because factor (1) does not exist. If a gasoline station begins operation at the subject property, then all three
risk factors will be in present, and the ground water resources will be vulnerable to contamination. If a gasoline
station is to be constructed and operated, then engineered containment will be the most effective means of mitigating
these risks by addressing factor (3)17
6.2.1 Subsurface release containment
.
Containment of subsurface releases is the most critical element in protecting the ground water resources. UST
system components can provide secondary or tertiary containment (such as double-wall piping or triple-wall tanks),
and regulations will require that these safeguards be installed for a system installed at the subject property (see
Section 4.1). Underground tanks themselves have become a less frequent source of subsurface releases than piping,
spill buckets, and other components [Schnapf, 2012]. In the case of a suspected release, the environmental
investigations that are required by regulation are intrusive by nature and must be performed in the vicinity of the
UST system, posing a potential risk of accidental damage to underground components. While the future use of
oxygenates is certain, the chemical nature of the oxygenates and their compatibility with fuel storage and delivery
systems is not certain (see Section 6.4 ) and it is possible the future leaks will be associated with their use.
6.2.1.1 Subsurface vault
By far, the highest level of protection of the ground water resources would be achieved by placing the UST system
in an underground vault (see Table 4-2). The vault would likely consist of a concrete structure that is lined with a
17 At present, there is not a method which is both technologically and economically feasible for addressing factor (2) over the lifespan of
the gasoline station.
Evaluation of the potential environmental impacts to ground water quality Page 13 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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Danville, Indiana 46122-0681 XenonGeosci.com
petroleum-resistant material, such as that manufactured by Liquid Boot or similar product (see Figure 1 for
conceptual sketch) and would be required to be constructed in accordance with the Indiana Fire Code 18
, which
requires specific protections to be included in its design, such as protection from soil and hydrostatic loads, seismic
(earthquake forces), uplift by ground water or flooding, loads imposed from above, and to be protective in the event
of an explosion.
Structural vault walls lined with water
tight, petroleum-resistant inner liner
such as . Sufficient capacity
to contain 110% of tank release.
Liquid Boot
Observation well with water
level indicator
Hydrocarbon and
oxygen sensors
Tank
fill
Man
way
dispensers
piping
Figure 1: Conceptual drawing of an underground vault.
The vault would allow spills and releases from the UST, piping, spill buckets or dispenser components to
be contained, readily detectable, and easily remediated
1. Spills or releases due to leaks in the UST system (tanks, piping, spill buckets) would be contained before
release to the environment.
. Beneficial aspects of a vault are as follows:
2. A vault would allow the visual inspection of the tanks and piping throughout the lifespan of the gas station.
This would allow early detection of leaks that might arise from failures of UST system components, leaks
attributable to oxygenate incompatibilities, faulty workmanship, etc.
3. The recovery of released product would be greatly simplified in contrast to any other containment option.
The released product could be recovered by a vacuum truck immediately upon arrival (whereas spills to
granular backfill or soil will slowly drain and need to be recovered over time.) Complete recovery could be
confirmed visually as well as quantitatively.
4. Unlike other monitoring scenarios that can be applied, release monitoring of a vault provides a failsafe
18 675 IAC 22
Evaluation of the potential environmental impacts to ground water quality Page 14 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
condition. The failure of release detection instruments that are installed in a UST, fill bucket, dispenser
sump, or well can allow the continued and undetected release of petroleum into the environment. The
discovery and correction a failed detection instrument could be too late to prevent contamination of the
ground water beneath the site. In comparison, the failure of detection instruments that are installed in a vault
may allow product to be released from the UST system, but the product does not impair the aquifer; it is
contained within the vault.
5. A vault system will serve as a barrier to hydrostatic pressures that would otherwise impact the UST system.
A properly designed and installed vault system will be in contact with the stresses associated with the
shallow ground water at the site and prevent potential damage to the tank system from buoyancy forces.
6. The integrity of the containment (the vault) can be inspected over time. Long-term degradation of the
protective layers can be visually assessed and the liner integrity can be upgraded as needed without
interruption of site operations.
7. A vault is the least likely containment system to be accidentally breached by environmental drilling or other
unanticipated activities. Underground storage tanks, piping and synthetic liners can all be breached during
intrusive activities 19
6.2.1.2 Impermeable liners
.
An engineered, impermeable liner could also be placed beneath the UST system. The greatest protection would be
gained from a contiguous synthetic liner that underlies the tanks, piping and dispensers. A contiguous liner would
allow spills and releases from the UST, piping, spill buckets or dispenser components to be contained, readily
detectable, and remediated without contamination of the surrounding soils. Disadvantages of a synthetic liner
include the inability to inspect the UST system, the inability to assess the degradation of the liner integrity over time,
the difficulty in repairing or modifying the liner if needed, and its susceptibility to damage by intrusive operations
such as drilling or excavation activities.
A clay layer can be constructed to provide an impermeable liner beneath the UST system. At their best, a clay liner
will provide equivalent protections as a synthetic liner but will also share their disadvantages listed above. A
significant, additional disadvantage is the lower certainty of execution of constructing an effective clay liner.
6.2.1.3 Multi-wall tanks, piping, spill buckets and dispenser sumps
The use of multi-wall tanks, piping, spill buckets and dispenser sumps is an option that is allowed by Indiana
regulations and their use is significantly superior to the use of single-wall components. This is the option that has
been proposed by both Turkey Hill and Ricker's. These systems are designed to completely contain releases from
tanks, piping, etc. by providing a tank-within-a-tank or pipe-within-a-pipe designs. This technology can provide
effective protection against manufacturing defects of the inner, fuel-containing components, but may not protect
against damage to UST system components that occur after their installation. Their complexity renders them more
vulnerable to workmanship issues during installation and maintenance operations. Components of the containment
system, such as dispenser sump seals, could be degraded as a result of material incompatibilities that may arise with
the mandated use of fuel oxygenates in the future (see Section 6.4 ).
6.2.2 Hydraulic containment (pumping)
One option is to install one or more recovery wells that are designed to establish hydraulic capture in the event of a
19 Xenon is aware of tanks being punctured by environmental drilling and excavating and piping systems being damaged by grade
stakes.
Evaluation of the potential environmental impacts to ground water quality Page 15 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
release. This would effectively require the installation of a pumping well capable of establishing a capture zone 20
5.2
as
needed to prevent the down-gradient flow of released petroleum. In addition to the well used to establish hydraulic
control, one or more shallow wells would be required to recover the product. Difficulties with this method is the
need to design the wells for future use when the ground water elevation and gradient may be different than it is today
(see Section ) and the volume of water that is pumped may need treatment before it can be discharged to a
surface pond or basin or to the sanitary sewer.
In the case that a subsurface leak has continued for an extended period prior to discovery, it is not certain that the
recovery well(s) will be able to achieve sufficient capture of the contaminant plume. If ground water flows toward
the north to northwest as is presumed (see Section 5.2.2 ), released product that has reached ground water could
migrate beneath 146th Street before the release is detected (i.e., before pumping is initiated). If the plume extends
beyond the cone-of-influence of the recovery well, there is a low likelihood that an additional well(s) would be
installed within the travel lanes of 146th Street. Consequently, any additional wells would likely be located along the
north side of the street, in the front yards of the residential properties, some of which use ground water as their
potable supply.
6.2.1 Surface spill containment
Design drawings submitted to the City of Carmel by both Turkey Hill and Ricker's have proposed that storm water
flow from the subject property would discharge to a storm water basin [WCC, 2010] or to a lined detention pond
located off-site [Creek Run, 2013], respectively. Neither submittal clarified whether the planned basins were to be
owned and maintained by the proposed owner of the gas station.
A bioretention pond or containment basin would need adequate freeboard to contain 110% the volume of the largest
volume that would be spilled to the ground surface. This would be the volume of a fuel tanker truck, which can be as
large as 9,500 gallons or more.
Valves would be required both upstream and downstream of the containment basin. The upstream valve would be
closed in the event of a large release in an attempt to contain the spill within the storm sewer structures and piping as
much as is possible. This would prevent a shock to the bioretention pond and/or the contamination of the retention
basin, and may be necessary if adequate freeboard is not available in the containment basin. A downstream valve
would also be closed in response to a large release to prevent the product from leaving the basin and entering
unprotected ditches and the Legacy BMP.
Because oil/grit separators rely on the tendency of petroleum to float on water, they are not able to remove
petroleum that has been emulsified by treatment with dispersants. It is essential that the station operators do not rely
on the use of dispersants for incidental petroleum spills if an oil/grit separator is utilized to remove petroleum from
storm water runoff.
Positive limiting barriers, which are groove cut into the concrete around the perimeter of the dispenser area, must be
maintained so that their ability to contain spills is not impaired. Seals at pavement joints will require routine
inspection for deterioration and maintenance as needed to prevent incidental gasoline spills from penetrating the
joints.
6.3 TREATMENT SYSTEMS
Once a release has occurred, it will be necessary to treat the impaired ground water or surface water to levels that are
protective of human health and the environment.
20 A capture zone is an area within which ground water will be pumped from a well. It differs from a cone of depression because water
can flow into and out of a cone of depression without capture.
Evaluation of the potential environmental impacts to ground water quality Page 16 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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Danville, Indiana 46122-0681 XenonGeosci.com
Table 6-1: Summary of selected subsurface containment options
Benefit Vault Contiguous
synthetic liner
Multi-wall tanks and
piping, spill buckets,
dispenser sumps(1)
Single-wall tank
with clay liner and
observation wells
Containment of spills or
releases before product
reaches the
environment:
Yes Yes Maybe No
Product collects in vault
until removal.
Product collects in lined
basin until removal.
Assumes contiguous
liner beneath complete
UST system.
System must be free
from defect and perform
as designed over its
lifetime.
Releases may move off-
site.
Product has already
reached ground water.
Likely to move off-site.
Visual inspection of
tanks and piping
throughout lifespan of
the gas station:
Yes No No No
Interior of vault would
be accessible for visual
inspections.
Liner buried and
backfilled with granular
material.
Inspection of only the
interior of spill buckets
and dispenser sumps.
Inspection of only the
interior of spill buckets
and dispenser sumps.
Recovery of spilled
product:
Immediate and complete
recovery.
Product could be
recovered over time.
Successful recovery is
questionable.
Least likely scenario for
recovery.
Recovery can be
confirmed visually as
well as quantitatively.
Recovery can be
quantitatively verified.
Long-term process. Long-term process.
Contamination of
aquifer as a
consequence of release
detection instruments
failure:
No No Maybe Yes
Undetected product
release does not impair
the aquifer.
Undetected product
release does not impair
the aquifer.
Possibility of a
continued and
undetected release to the
environment.
Possibility of a
continued and
undetected release to the
environment.
Integrity of
containment liner over
the lifetime of the gas
station:
Greatest protection Moderate Vulnerable Vulnerable
Containment integrity
can be inspected,
upgraded, repaired.
Liner material can be
updated if future fuel
additives raise
compatibility issues.
Dewatering may be
required to prevent
buoyancy issues and
hydraulic pressures at
vault seams.
The integrity of the liner
can be assessed or
modified only by
excavation.
Loss of integrity may be
discovered only by
release discovery.
Dewatering may be
required to prevent
buoyancy issues and
hydraulic pressures at
liner seams.
Vulnerable to damage
and workmanship flaws
during routine
maintenance
Vulnerable to
compatibility issues with
future fuel additives.
Loss of integrity may be
discovered only by
release discovery.
Vulnerable to damage
and workmanship flaws
during routine
maintenance
Vulnerable to
compatibility issues with
future fuel additives.
Loss of integrity may be
discovered only by
release discovery.
Protection against
accidental damage to
containment barriers:
Greatest protection Low protection Low protection Low protection
High level of protection
if vault is constructed of
concrete.
Liner can be easily
penetrated by heavy
equipment and may not
be noticed.
UST system components
can be penetrated by
heavy equipment.
UST system components
can be penetrated by
heavy equipment.
(1) This is the option proposed by Turkey Hill and Ricker's
Evaluation of the potential environmental impacts to ground water quality Page 17 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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Danville, Indiana 46122-0681 XenonGeosci.com
6.3.1 Ground water treatment
Contaminated ground water is treated either in-situ (in-place) or ex-situ (after pumping to the ground surface).
Examples of in-situ methods include the injection of nutrients to encourage the metabolism of the petroleum by
indigenous or introduced microbes, or the addition of chemicals needed to oxidize the petroleum constituents or
promote their volatilization. With ex-situ systems, ground water is treated at the ground surface by methods such as
carbon filtration, enhanced volatilization, or in bioreactors. Ex-situ treatment schemes require the installation of
hydraulic control and recovery wells. Although surfactants are sometimes utilized to mobilize contaminants from the
aquifer to facilitate their recovery by pumping, care must be taken to assure that the surfactant treatment does not
mobilize contaminants that will not be captured because they may ultimately reach the locations of nearby
residential supply wells. Significant hydrogeological evaluation must be performed before the contamination can be
effectively treated by either in-situ or ex-situ methods. The contaminant plume to migrate even farther during the
time needed to complete the evaluation and have it reviewed and approved by IDEM.
6.3.2 Surface water treatment
As required by their NPDES general permit, the City of Carmel will require a gas station at the subject property to
implement one or more BMPs to effect a reduction of pollutants of concern from its runoff (see Section 4.6.3).
Likely solutions include the installation of oil/grit separators, filters, and devices installed in storm structures, such
as snouts and/or bio-skirts. However, each of these BMPs are limited in their ability to remove pollutants from storm
water runoff during flows that exceed design conditions and are not designed to contain a catastrophic spill from a
delivery tanker truck or other large-volume spills.
6.3.2.1 Snouts and Bio-skirts
A snout is a fixture mounted inside a storm structure. It is a hood that covers the outlet pipe in a manner that allows
water to discharge only through a downward-facing port. This prevents floatable materials from leaving the outlet
pipe once the water level is greater than the hood's inlet port.
The bio-skirt devices are designed to remove petroleum hydrocarbons from storm water and can be expected to be
compatible with volatile organic compounds. Product information by its manufacturer [BMP, 2013] states that the
media used to construct the Bio-Skirt has been shown to significantly reduce hydrocarbons including motor oil,
diesel fuel, PAHs and emulsified oils. The ability to reduce volatile components such as BTEX 21
6.3.2.2 Oil/grit separators
compounds was
not addressed in the product information.
Oil/grit separators have limited capability to contain spilled petroleum due to low average detention times, and have
the added risk that settled material may be re-suspended or released during later storms [U.S. EPA, 1999]. The
manufacture of the Stormceptor units state that their performance standards assume low petroleum concentrations,
volumes and low flow rates, and higher concentrations and/or flows will decrease the separator's performance [ISC,
2011]. The manufacturer of Aqua-Shield units claim the Aqua-Swirl® AS-4 reduced the concentration of total
petroleum hydrocarbons (TPH) (as waste oil) in the influent and effluent grab sample at flow rates of 300
gallons/minute [Aquashield, 2011]22
Because the separators rely on the tendency of petroleum to float on water, they are not able to remove petroleum
that has been emulsified by treatment with dispersants. It is essential that the station operators do not rely on the use
of dispersants for incidental petroleum spills.
.
21 benzene, toluene, ethylbenzene and m-, o- and p-xylenes 22 the manufacturer's test consisted of 600 gallons of water and 5 gallons of waste oil at a flow rate of 21.1 gpm/ft2.
Evaluation of the potential environmental impacts to ground water quality Page 18 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
6.3.2.3 Filters
Storm water filters can be utilized to remove petroleum and metals from storm water. Some oil/grit separators, such
as the Aqua-Filter unit proposed by Ricker's [Creek Run, 2013] can remove high levels of suspended solids, thereby
reducing the amount of PAHs and heavy metals that are adsorbed to the solids. Informational literature provided by
the manufacturer of the unit suggests that a TPH (as diesel fuel and motor oil) removal efficiency of 92.1% can be
achieved. The Aqua-filter units can be manufactured in HDPE or coated steel, so it will be essential that material
compatibility can be documented. Treatment filters require routine inspection and eventual replacement. The spent
filters will require disposal in accordance with applicable local and state regulations.
6.3.2.4 Bioretention and treatment pond
A bioretention and treatment pond or basin could be a seasonally effective means of treating any volatile petroleum
constituents that pass through up-stream units such as snouts, bio-skirts or separators. Evaporation will be a
significant treatment mechanism for small spills of volatile hydrocarbons (BTEX) that reach the pond. PAHs and
metals will have a strong tendency to sorb to organic material and small particles 23
Both the Turkey Hill submittal included a design for a storm water basin [WCC, 2010], and the Ricker's proposal
included one drawing that appeared to be the same basin [Creek Run, 2013]. The Turkey Hill design drawings show
the elevation of the floor of the basin (746 ft.) to be at a lower elevation than the bottom of the silty soils reported in
the soil boring logs at the subject property [A&W, 2007]. This suggests that the basin would be excavated into the
underlying sand deposits that overlie the aquifer. A gas station will generate storm water runoff with increased
pollutant levels and runoff flowing into the basin would provide a means for pollutants to infiltrate the sand and
percolate to the ground water. A lined retention basin or subsurface vault will therefore be necessary to provide
adequate protection of the aquifer.
within the pond. Petroleum may
be reduced through biodegradation and both petroleum and metals may be reduced by plant uptake. The biologic
removal mechanisms are less certain than the others and will be not be effective in months when plants are dormant
[Kadlec, 2009] or if the pond is dry.
It is essential that the owner/operator of the service station also be the owner/operator of any retention basin that is
relied upon to contain petroleum releases from the facility. Paired ownership is essential because the retention basin
will be relied upon for protection not only from day-to-day releases and containment of sediment, but also for
protection from the less likely but potentially catastrophic release of large volumes of petroleum resulting from a
tanker accident, fill-hose failure, or similar incidents.
6.3.2.5 Disposal of accumulated sediments
Accumulated sediment will need to be removed from the oil/grit separators and treatment ponds or basins, if used.
Separator units are inspected and pumped by a vacuum service as needed to assure their proper functionality. Clean-
outs typically occur on a 6-month to one-year basis but the actual schedule will be determined by the rate of
sediment accumulation and the recommendations of the BMP manufacturer.
If a dry retention basin is used, sediment may need to be removed from the inlet area of the retention basin to assure
proper discharge from the inlet pipe. Maintenance intervals can be expected to be on the order of 6 months or as it
accumulates. Sediment will also need to be removed from the retention basin as needed to assure its continued
design capacity. This removal is commonly recommended at periods on the order of every 5 to 10 years or when
sediment accumulation reaches a thickness of 0.5 - 1.0 feet, though the actual maintenance period will need to be
determined by the engineer of the retention basin.
23 including clay minerals, aluminum, iron and manganese oxides and hydroxides, humic materials and biofilms [Miller, 2007].
Evaluation of the potential environmental impacts to ground water quality Page 19 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
The accumulated sediments may not be able to be disposed of at the ground surface. Because it is likely that the
sediment will contain increased concentrations of heavy metals, PAHs and other pollutants [U.S. EPA, 1999], this
material must be tested prior to disposal. At minimum, an analysis for the Priority Pollutant 24 parameters is
suggested, and any sediment that contains any single pollutant concentration that exceeds the IDEM screening levels
for residential exposures or soil-migration-to ground water [IDEM, 2013c] must not be disposed onto the ground
surface, where it will be in contact with surface or ground water, or within an established well head protection area.
Any sediment that contains pollutant levels in excess of hazardous waste toxicity characteristic thresholds 25 will
need to be disposed in accordance with RCRA 26
6.3.3 Compatibility of storm water BMPs with petroleum fuels
. In every case, the removed sediment must be disposed in
accordance with applicable local and state regulations.
Some components of the storm water system may exhibit poor compatibility with petroleum hydrocarbon
compounds that are found in gasoline (BTEX) and/or biofuels.
Oil/grit separators can be manufactured from a variety of materials and it will be important to ensure material
compatibility with fuels and their additives. Stormceptor® units contain a fiberglass insert located inside the precast
concrete vault and extending into the treatment chamber, providing dual wall protection against volatile
hydrocarbons.
Various sources indicate that HDPE is not compatible with exposure to gasoline constituents and testing has shown
damage to HDPE on exposure to toluene, xylenes and diesel fuel [Maru et al., 2009; CPL, 2013]. However, other
sources indicate that HDPE does not soften or lose strength when exposed to gasoline [ADS, 2013] and in fact,
dispenser sumps and consumer-grade gasoline cans are manufactured from HDPE. Our research indicates this
discrepancy may result from the type of HDPE utilized, their exposure periods and the temperature ranges of the
various tests.
Pipe seals and connections to other components are another area where product compatibility will need
consideration. For example, Kor-N-Seal boots, which are used to obtain a leak-proof coupling between sewer lines
and concrete storm structures are manufactured from EPDM polymer compounds [Snyder, 2013]. Testing has shown
EPDM to be unsuitable for use with "Benzine (Gasoline)" [TPSM, 2012].
Because of the possibility of compatibility issues, it will be critical that the developer provide documentation of
compatibility of all materials with petroleum, automotive fluids and possible fuel additives, such as ethanol.
6.4 ETHANOL AND OTHER REGULATION-DRIVEN ADDITIVES
Under the Renewable Fuel Standards27
6.4.1 Known incompatibility with UST system components
(RFS), the U.S. EPA establishes the volume requirements and associated
percentage standards for cellulosic biofuel (including corn ethanol), biomass-based diesel, advanced biofuel, and
total renewable fuel. The RFS required petroleum refiners to the blend renewable fuel into transportation fuel in
increasing amounts each year, escalating to 36 billion gallons by 2022 [U.S. DOE, 2013]. Although its total use is
significantly less than that of ethanol- blended gasoline, biodiesel is becoming increasingly available across the
United States.
The chemical and physical properties of ethanol and biodiesel can make fuel which contains them more degrading to
24 see Appendix A to 40 CFR 423 25 40 CFR 261.24 26 Resource Conservation and Recovery Act 27 40 CFR Subparts M and K
Evaluation of the potential environmental impacts to ground water quality Page 20 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
certain UST system materials than petroleum alone [IDEM, 2007],[U.S. EPA, 2011]. The corrosive nature of alcohol
blended fuels with regard to metals and polymers alike is well documented. The presence of alcohol enhances the
swelling of polymers; even in relatively dilute alcohol blends, considerable loss of stiffness and strength are well
documented for many polymeric materials. A blend of 15 percent ethanol in gasoline is indicated as the point which
the maximum swelling occurs in polymeric materials [Westbrook, 1999]. The presence of trace components such as
water, chloride ion, sulfur compounds, pH, etc. play a role in metal corrosion by gasohol-containing gasolines.
The U.S. EPA has commented on these issues as follows: "EPA understands that the chemical and physical
properties of ethanol and biodiesel can be more degrading to certain UST system materials than petroleum alone, so
it is important to ensure that all UST system components in contact with the biofuel blend are materially compatible
with that fuel. Industry practice has been for tank owners to demonstrate compatibility by using equipment that is
certified or listed by a nationally recognized, independent testing laboratory, such as Underwriters Laboratories (UL).
However, based on EPA’s understanding of UL listings, many UST system components in use today, with the
exception of certain tanks and piping, have not been tested by UL or any other nationally recognized, independent
testing laboratory for compatibility with ethanol blends greater than 10 percent. In addition, EPA is not aware of any
nationally recognized, independent testing laboratory that has performed testing on UST system components with
biodiesel-blended fuels. Absent certification or listing from a nationally recognized, independent testing laboratory,
or other verification that equipment is compatible with anything beyond conventional fuels, the suitability of these
components for use with ethanol or biodiesel blends comes into question." 28
The rate of permeation of fuel components through structurally sound fiberglass tanks and fiberglass piping into the
ground is expected to be very low, perhaps below detectable limits [Westbrook, 1999]. The Xerxes Corporation, a
manufacturer of fiberglass UST systems, states in their sales literature that "Xerxes confidentially holds to its
longstanding 30-year warranty, which explicitly provides 30 years of internal corrosion coverage 'with or without
water bottoms' "[Xerxes, 2013].
Oak Ridge National Labs reported on tests of metals, elastomeric compounds 29 and sealants used in the manufacture
of UST systems. They tested the materials for compatibility with fuels containing various amounts of ethanol. In
their test of various metal alloys in the absence of free water 30
Underwriters Laboratory performed a study focused on the performance of fuel storage and dispensing components
as opposed to metals, elastomers and sealants. Some equipment had compliant results; shear valves and flow limiters
produced compliant results, a submersible turbine pump performed well, and hoses generally yielded compliant
results. Other equipment demonstrated limited ability to safely accommodate exposure to fuels with higher ethanol
content such as E15. Most non-compliant results involved gaskets and seals, but also polymeric parts. Dispenser
meter/manifold/valve assemblies in particular demonstrated largely noncompliant results. [Boyce and Chapin, 2010]
found very little corrosion of the metal. Elastomeric
compounds were found to be susceptible to damage from exposure to ethanol at relatively low levels. Ethanol was
found to increase the volume swell and produce softening of various elastomeric compounds. Sealants exhibited
varying results depending on the type of sealant and the ethanol content. It was suggested that standard sealants may
not be compatible without additional sealing by Teflon products. Ethanol-resistant sealants prevented leakage
according to the ASTM standard. [ORNL, 2011]
EPA has stated that some tank operators are storing blends of biodiesel and petroleum diesel ranging from 2% to 99%
biodiesel in underground storage tanks, with the vast majority of biodiesel tanks storing biodiesel at concentrations
of 20% or less. EPA recognizes that there is little information regarding the compatibility of UST system equipment
28 Federal Register / Vol. 76, No. 128 / Tuesday, July 5, 2011 / Notices 29 Elastomeric compounds include polyurethane, silicone rubber, fluorocarbons and others. 30 In their laboratory testing, ORNL controlled the fuel blend to assure that water did not separate from the fuel as a separate phase.
Phase separation may occasionally occur in retail settings [ORNL, 2011].
Evaluation of the potential environmental impacts to ground water quality Page 21 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
with biodiesel blends, and that there are known compatibility issues for pure biodiesel (B100)28. The National
Renewable Energy Laboratory has determined that pure biodiesel ‘B100 will degrade, soften, or seep through some
hoses, gaskets, seals, elastomers, glues, and plastics with prolonged exposure , and that nitrile rubber compounds,
polypropylene, polyvinyl, and Tygon® materials are particularly vulnerable to B100 [NREL, 2009].
6.4.2 Future oxygenates
Due to incompatibilities of ethanol with components of mechanical systems, the future use of ethanol as an
oxygenate seems to be anything but certain. For example, a review of news headlines indicate that Chrysler, Nissan,
Toyota, Volkswagen and BMW have stated their warranties do not cover damages related to use of E15, and eight
other automakers have told AAA 31
Our research of the possible use of alternative fuel oxygenates and a discussion with a member of U.S. EPA Region
5
that they may cancel warranty coverage depending on what needs to be repaired.
Porsche specifically approves the use of E15 fuels on models built since 2001, and Ford and General Motors have
approved E15 for flex-fuel vehicles built in 2012 and 2013, respectively.
32
6.5 UST SYSTEM MAINTENANCE
has identified isobutanol as a potential candidate. Unfortunately, there is not a significant body of literature for
isobutanol as there is for ethanol in regards to the compatibility of the additives as fuel storage and dispensing
systems. Two manufacturers of isobutanol tout its virtues. Gevo is a biofuels company that states that isobutanol has
no stress corrosion cracking compatibility or elastomer incompatibility issues [Gevo, 2013]. Butamax, states that
"isobutanol impacts on elastomers are typically intermediate between those of hydrocarbon gasoline and
gasoline/ethanol blends" [Baustian, 2012]; biobutanol can presently to be blended with gasoline at 16% by volume
versus 10% for ethanol.
On-going maintenance and future upgrades to the UST system can introduce risks of releases of petroleum to the
environment resulting from material incompatibilities as well as mechanical failures and human error. There is
growing evidence that many properties with new or upgraded USTs may be impacted by equipment that is
improperly installed or operated [Schnapf, 2012]. All mechanical systems will fail over time, and the regular and
proactive maintenance of the systems at the site will be essential to the prevention of spills and releases over the
service use of the property. The various systems that will be susceptible to failure include the UST system, the
release detection system, containment system, and the storm water treatment system. In addition, adverse weather
conditions can contribute significantly to the degradation of equipment that was engineered to provide protection
from surface and subsurface releases. Proper and proactive maintenance and replacement of system components are
an essential element in the prevention of long-term, low-level releases.
6.6 UST SYSTEM UPGRADES
IDEM has established requirements for the conversion of existing UST systems to be able to handle blends with
higher ethanol content [IDEM, 2007]. IDEM requires to owner to verify that the dedicated fuel path is compatible
with the percent of ethanol to be stored and dispensed. They recommend the owner contact their petroleum
equipment supplier or an Indiana-certified installer to discuss converting to a higher percent ethanol blend and
ensuring that the UST system is appropriately equipped. The owner is required to verify that the following
equipment, components and materials are compatible with the ethanol blend that is intended to be stored and
dispensed:
31 The American Automobile Association 32 Mr. Mark Restaino, July 20, 2013.
Evaluation of the potential environmental impacts to ground water quality Page 22 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
• Fill pipe/drop tube
• Auto shutoff or overfill valve
• Tank (Is the warranty in effect? Is it certified or UL listed for the product stored?)
• Internal lining material used on relined tanks
• Submersible pump and pump impeller
• Gaskets, bushings, couplings
• Line leak detectors
• Leak detection equipment (ATG probes, floats, sump sensors)
• Piping material (UL listed or certified by manufacturer)
• Pipe adhesives/glues
• Flex connectors, grommets
• Spill containment and sumps
The following items which are not regulated by 329 IAC 9:
• Filters
• Dispensers
• Hoses, including breakaway couplings or fittings
• Nozzles
IDEM requires the tank owner to submit a Notification for Underground Storage Tanks (Form 45223) to the
Underground Storage Tank Section indicating the change of product that will be stored in the UST. The form must
be signed by the UST system owner.
6.7 MAINTENANCE OF OBSERVATION WELLS AND SIMILAR STRUCTURES
Observation and monitoring wells are common installations at retail gasoline stations. These installations provide a
means to detect the presence of petroleum vapors in soil or ground water, and to measure the ground water elevation.
In the case of an actual release, IDEM regulations and guidance documents require the installation of ground water
monitoring wells as part of site investigation activities.
The presence of these wells represents a direct conduit from the ground surface to ground water in the underlying
aquifer. In the ideal case, the well covers are securely sealed by the means of a steel lid that is bolted to an annular
ring that is installed in the concrete pavement. Over time, the steel lid and annular ring rust. The presence of rust and
scale diminish the ability of the rubber lid gasket to prevent the flow of surface water into the annular space around
the well casing. Lid bolts can become difficult to tighten, which prevents an effective seal from being achieved. In
some cases, the lid bolts can seize in the ring and may be sheared off, leaving it impossible to effect a seal without
corrective measures. In addition to rust issues, snow removal efforts can cause significant damage or complete
removal of well covers.
The improper maintenance of spill buckets may contribute to significant soil and ground water contamination [U.S.
EPA, 2012]. Spill buckets are often damaged in winter months during snow removal activities [Schnapf, 2012] and
must be repaired and tested.
6.8 OPERATOR TRAINING
Federal and state regulations require that a gas station will have on site at all times one or more employees (operators)
who has received training in response to routine spills, cleaning and containment of contaminated storm water,
emergency spill response and emergency notification procedures (see Section 4.2 ). The attendant/cashier-level
employees receive Class C operator training which must include an understanding of the alarms caused by spills,
leaks, or releases from UST system, and how to take appropriate action in response to emergencies that require
immediate action, including situations posing an immediate danger or threat to the public or to the environment.
Evaluation of the potential environmental impacts to ground water quality Page 23 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
Because the subject property is within a hydrogeologically sensitive area, it is essential that the operators receive
detailed training on site-specific issues in addition to the less specific issues listed above. This specific training
should include the following types of items:
• The nature of the site susceptibility to contamination, including the permeable nature of the aquifer and its
use as a drinking water supply for residential and municipal wells;
• Training on the function and operation of storm water capture, treatment and storage systems, recognition of
conditions that can impair their proper function (i.e., blockage by debris or reduced retention basin
freeboard due to heavy rains), recognition of conditions indicating the potential need for maintenance or
failure of the systems (i.e., sheen on discharge water or physical damage), and recognition of conditions
where the systems are being by-passed (i.e, due to snow storage or blockage of positive limiting barriers).
• Training on site-specific emergency procedures, such as blocking stormwater inlets or the operation of
storm water discharge valves to prevent large spills from leaving engineered storage areas. The employee
should be aware of access requirements for performing emergency procedures and to recognize and prevent
conditions that could prevent access (i.e., obstruction by obstacles or snow storage).
6.9 GROUND WATER PROTECTION PLAN (GWPP)
The thoughtful preparation and thorough implementation of protective plans will be necessary for the protection of
the aquifer beneath the project area. At a minimum, the Ground Water Protection Plan (GWPP) should incorporate
elements that are commonly contained in other plans, or it can integrate the plans into a single cohesive document.
The GWPP must address storm water protection, spill prevention and control measures, and spill planning and
response. Site maintenance and operations are important factors, as is employee training. This section addresses the
components of the GWPP, even though they may be developed as separate plans.
6.9.1 Storm water pollution prevention
The GWPP must address inspection and maintenance schedules for the storm-water structures management system,
including BMPs, positive limiting barriers, and shut-off valves for the retention pond. The plans should address the
frequency and content of inspections of the saturation of sorbent materials, bio-skirts, and storm-water filters. There
should be a discussion on the monitoring of sediment accumulations in storm-water structures and basins and the
means of characterizing the sediment prior to disposal. The GWPP should address potential obstacles to the proper
functioning and inspection of storm water components, such as plowed snow blocking inlet structures or outlet pipes.
[This information would typically be included in a Storm Water Pollution Prevention Plan but IDEM does not
require a retail gas station to obtain NPDES permits; see Section 4.6.2
6.9.2 Spill prevention and response
The GWPP must address spill prevention and response measures for the facility. It is essential that the plan
recognizes that the facility is within a hydrogeologically-sensitive area.
It must contain an estimate of the maximum quantity of fuel that could be spilled in the event of a delivery truck
failure or other equipment failure. It should present possible spill or release scenarios and an analysis of spill routing,
treatment and containment as needed to prevent contamination of ground water or surface water. The plan should
address instructional signage, labeling and operation of emergency shutoff switches, notification lists for responding
to spill incidents (names and phone numbers of management, fire and police, local and state agencies and spill
response contractors).
Evaluation of the potential environmental impacts to ground water quality Page 24 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
If the site is designed so that runoff from separate areas is segregated, the plan must detail the routing of spills or
runoff to treatment units, vaults, basins, etc. The plan should include descriptions of containment and/or diversionary
structures or equipment needed in the event of a spill, and a demonstration that the needed equipment, personnel,
and other resources would be available to respond to a spill.
The plan should require that small spills in fueling areas are treated with dry methods such as rags or absorbents.
The plan should specify that an adequate supply of absorbent materials be kept readily available and provide
guidance to the employees for the proper disposal of used rags and sorbent material.
6.9.2.1 Dispersant/surfactant use
It is common for gas station operators to respond to incidental gasoline spills with the use of dispersants or
surfactants. These products increase the solubility of petroleum constituents in water, allowing the spills to be treated
and then rinsed away. Dispersants break up petroleum into very small droplets in water. The use of dispersants as a
clean-up agent for fuel spills to the ground surface will be detrimental if an oil/grit separator is employed because
the separators are not designed to remove emulsified petroleum [RMC, 2013]. The dispersive effect is temporary and
the petroleum can later reform and accumulate on the water surface. Vapors can then be regenerated in storm sewer
pipes or structures, in oil/grit separators, or at a ditch or basin. U.S. EPA policy does not allow the use of dispersants
in fresh water.
Surfactants are used to mobilize contaminants in the subsurface by increasing reducing their solubility while
lowering the surface activity of water and capillary actions [Moyer and Kostecki, 2003]. The use of surfactants to
mobilize contaminants is beneficial for their recovery by ground water pumping. However, when used to clean up
surface spills, the increased mobility can result in increased rates of contaminant percolation into the soil and
migration through ground water.
6.9.3 Site maintenance and operations
All mechanical systems will fail over time, and the regular and proactive maintenance of the systems at the site are
essential to the prevention of spills and releases over the service use of the property. The various systems that will be
susceptible to failure include the UST system, the release detection system, containment system, and the storm water
treatment system. In addition, adverse weather conditions can contribute significantly to the degradation of
equipment that was designed to provide protection from surface and subsurface releases. Proper and proactive
maintenance and replacement of system components are an essential element in the prevention of long-term, low-
level releases.
The GWPP should address site maintenance procedures to assure that maintenance activities do not impair the
proper functioning of the UST system, dispensers, storm-water BMPs, spill containment devices, or leak detection
systems. For example, snow plowing or maintenance cannot be permitted to interfere with the proper operation of
the storm water system and cannot impede access to critical spill response areas, such as emergency flow valves for
a retention basin. Waste fluids or used paint must never be emptied into the storm water system.
Maintenance requirements for PLBs and the storm water management system, including BMPs must be outlined.
It is essential that maintenance to the fuel storage and dispensing systems be performed with the utmost care and
diligence. Every repair or maintenance operation on the UST system poses an additional risk of a release due to
workmanship and/or material failure. As future fuels may include increased use of ethanol and/or other additives,
materials such as seals, joint compounds and connectors that are compatible with today's fuels may not be
compatible with fuels in the future.
Evaluation of the potential environmental impacts to ground water quality Page 25 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
7 RELEASE SCENARIOS
A large proportion of releases occurred from steel tanks at the beginning years of UST regulations and the use of
fiberglass tanks has reduced the number of tank releases [IDEM, 2013a]. However, it is clear that releases are not
rare (see Figure 2). Petroleum releases now occur more frequently from piping failures than from the tanks
themselves, and evidence suggests that installation issues and operational failures have become the most significant
source of failures [Schnapf, 2012].
The potential release conditions will fall into one of four categories depending on whether they occur routinely or
under catastrophic conditions, and whether the pollutants are released to the ground surface or to the subsurface. The
most likely release will be spills of gasoline and automobile drippings to the ground surface. These are expected to
be persistent over the life of the facility while relatively small in volume. Less likely put significant risks would arise
from catastrophic releases of thousands of gallons from the UST system or onto the ground surface.
Once released, gasoline or diesel fuel would percolate vertically through the sandy aquifer materials until it
encounters ground water. Because petroleum is less dense than water, it will float above water table. Over time, the
petroleum will dissolve in the ground water and the contaminated ground water would likely flow toward the north
to northwest under the influence of large-capacity public supply wells and would pass residential wells along the
way.
7.1.1 Persistent, low-volume releases
This category includes the release and spillage of small amounts of petroleum over long periods of time. The
occurrence of chronic spills of gasoline during fueling operations by customers is certain, and the possibility of long-
term releases from UST system components cannot be ruled out.
Incidental, low-volume spills of fuel by customers is a frequent occurrence. A study calculated that conventional
fueling nozzles released 0.61 lbs per 1,000 gallons of dispensed product, while vapor recovery nozzles released 0.42
lb spillage/1,000 gallons of dispensed product[Morgester et al., 1992]. However, these are typically very low
volume occurrences that would typically evaporate before running off-site.
Larger spills to the ground surface have the potential to percolate through the near-surface sand units to the aquifer
from leaks in the storm water system, gaps in pavement joints, or in unlined swales or basins. The impacts of these
releases can be mitigated by the thoughtful design of the facility in terms of spill routing and containment and by
implementing effective spill response policies by employees.
7.1.1 Sudden, large-volume releases
Large-volume fuel releases occur from a variety of circumstances. Queries of agency databases listing historical fuel
spill statistics and a review of internet news services listing recent incidents have identified a broad range of
circumstances that result in rapid releases of 10s to 1,000s of gallons of fuel. These incidents include single- and
multi-car accidents, mechanical failures, cars running over delivery truck fuel lines, foiled theft attempts, cars
leaving while the fill hose is still engaged in the tank, and many other assorted accidents.
A retail gasoline station located at the Legacy property is likely to have high traffic volume and to sell large
quantities of petroleum fuels. This activity increases the chance of accidents that have the potential to release large
quantities of fuel to the ground surface. A query 33
33 Query terms were: Type of call = incident reports; Incident Type = mobile; Incident Cause = transport accident; Material Name =
gasoline; and Medium Affected = land.
of the online database from the National Response Center
Evaluation of the potential environmental impacts to ground water quality Page 26 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
Table 7-1: Release scenario matrix
Persistent, low-volume releases Sudden, large-volume releases
Subsurface
releases
• faulty installation, maintenance or upgrade
• component failures due to fuel
incompatibility
• chronic system leaks below sensor detection
limits
• uncontained drippage due to damaged spill
buckets
• environmental or geotechnical boring
through UST or piping
• accidental excavation of UST or piping
• buoyancy stresses on UST system
Surface releases • fill-up overflows, hose drippage
• faulty installation, maintenance or upgrade
• leaks from storm water BMPs
• material incompatibilities in UST system or
storm water BMPs
• tanker truck rupture
• hose/coupling failure due to run-overs or
equipment failure
• operator error
1985 1990 1995 2000 2005 2010
year
0
20
40
60
nu
mb
e
r of en
trie
s
8
3 3
32
54 53
33 33
36
22
28 29
31
29
12 11 10
20
18
26 25
22
26
19
10
19
6 5
Figure 2: Number of entries in IDEM LUST report that occurred in wellhead protection areas
Evaluation of the potential environmental impacts to ground water quality Page 27 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
indicated that there were over 700 spill incidents involving gasoline since 1990; approximately 500 of these directly
involved fuel delivery trucks and/or accidents at retail gasoline stations [National Response Center, 2013].
Catastrophic accidents involving the fuel delivery tanker trucks have the potential of releasing 9,000 gallons or more
to the ground surface of the facility. While the likelihood of a tanker truck release is comparatively small, it is not
insignificant. A study performed in Washington states that "... tanker truck accidents have resulted in multi-thousand
gallon spills with some regularity over the years. These tanker truck spills pose a significant threat to public health
and safety in addition to environmental damage." [Neel et al., 1997]
Current UST regulations require that soil and ground water samples be collected from areas where contamination is
most likely to be present34
8 ENVIRONMENTAL IMPACTS
which is reasonably understood to be in the vicinity of the UST, piping and dispensers.
IDEM recommends that samples be collected from at least 14 borings in each 0.5-acre source area [IDEM, 2013c].
The environmental investigations using heavy equipment presents a risk of accident that is not insignificant.
Spills and releases of petroleum products to the land surface can have serious public health consequences if the
product reaches drinking water supply wells, and potential public safety concerns if large quantities of spilled fuel
are routed to surface containment basins.
Ground water beneath the subject property will reach wells operated by Citizens Energy Group [CEG, 2013] and
others in less than one year (i.e., it is within the one-year time-of-travel boundary of Citizens' wellhead protection
area)35
The potential environmental impacts resulting from the operation of a gas station will be determined by the
conditions of the releases or spills, hydrogeological conditions that determine the rate of flow of product and ground
water, the nature and amount of contaminants that are released to the environment, and the exposures resulting from
human and environmental contact with the contaminated media.
. Because of the relative distance between the CEG wells (1,700 feet or more) and the residential wells (350
feet or more), the ground water could be expected to reach some residential wells in significantly less time.
Consequently, there would be little time to discover, respond, characterize and remediate the affected ground water
before it has the potential to impact drinking water supply wells.
8.1 AQUIFER VULNERABILITY
The USGS considers the vulnerability of ground water resources to be dependent on three environmental factors: (1)
the presence of contaminant sources, (2) the combination of physical and chemical processes in the subsurface
which affect contaminant concentrations in an aquifer; and (3) the ease with which water and contaminants can
travel to and through an aquifer [Eberts et al., 2013].
Factor (1) is the only one of the three that does not exist at the subject property today. The construction and
operation of a gas station will meet the criteria of factor (1) and the aquifer will become vulnerable. IDEM currently
reports 57,697 entries in their registry of registered underground storage tanks [IDEM, 2013d]. In comparison, their
list of leaking USTs includes 16,839 entries [IDEM, 2013b], a ratio of 29%. Approximately 4% (n = 742 entries) of
all LUST entries are for releases within wellhead protection areas (n = 623), ecologically sensitive areas (n = 56) or
geologically sensitive areas (n=63). The same data also indicate that 40% of the entries (n = 250) are still under
"active" status.
34 329 IAC 9-4-3 and 329 IAC 9-5-3.2 35 These calculations are typically performed by numerical modeling.
Evaluation of the potential environmental impacts to ground water quality Page 28 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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Danville, Indiana 46122-0681 XenonGeosci.com
Factor (2) is less well characterized because of the absence of data pertaining to the local physical and chemical
processes within the aquifer system. Regional studies have concluded that the higher ground water recharge rates,
shorter ground water travel times, and widespread anoxic conditions which are present in the northern glaciated
aquifers (Connecticut and Ohio) lead to greater vulnerability of public supply wells to contamination from volatile
organic compounds such as benzene and toluene [Kauffman and Chapelle, 2010].
Factor (3) is well characterized, as it is known that permeable sand deposits occur within five feet of the ground
surface [A&W, 2007] and extend to the depth of ground water within Legacy and surrounding areas [IDNR, 2013].
Because the permeable deposits lie at a shallow depth beneath the ground surface, the aquifer is highly susceptible to
contaminant spills at the ground surface or shallow subsurface [Basch, 2013].
8.1.1 Presence of contamination sources
Underground storage tanks would be large enough [Xerxes, 2013] that the tank excavations would be in intimate
contact with the permeable deposits. The Turkey Hill submittal included plans for a storm water basin [WCC, 2010]
and the Ricker's submittal included a drawing of what seemed to be the same basin. The basin had a base elevation
lower than the top elevation of permeable sands at the subject property. Therefore, releases from the UST system or
pollutants in surface water flowing into the storm water basin will have a permeable pathway to ground water.
Observation wells that are installed for the purpose of release detection and monitoring will be designed to provide
surface access directly to ground water, and damage to observation well covers or seals will allow surface pollutants
to reach ground water.
Small, persistent leaks from a UST system can be undetected for significant periods of time. The cumulative mass of
the petroleum released will be one of the key drivers of the horizontal extent of the resulting contaminant plume.
Some spillage is inevitable from the fueling of the underground tanks by the tanker trucks. Other releases can occur
from the storage system itself (tanks, piping, etc.) as a result of mechanical wear and failures, faulty workmanship
during system installation or maintenance, or to material incompatibilities. Although state regulations require UST
systems that are installed within wellhead protection areas to meet more stringent criteria, compliant systems can
potentially leak 70 gallons/month of product without detection (see Table 4-1). In contrast, a catastrophic release
would be noticed immediately, but could place thousands of gallons of gasoline into the aquifer. A chronic,
undetected release can create an extensive benzene plume that extends off-site and toward drinking water supply
wells. The technical difficulties in recovering product resulting from a catastrophic release to the aquifer will also
result in extensive ground water contamination.
Surface water pollution must be considered as a source of ground water contamination. Petroleum and heavy metal
pollutants will accumulate on the ground surface during the routine operation of a gasoline station from sources such
as routine spills during fueling, automotive fluids leaked by vehicles, and compounds that escape with exhaust or are
deposited with tire wear. These pollutants will be flushed by rainfall into the storm water system and then routed to
discharge. [Petroleum compounds occur at a typical concentration of 3.5 mg/L in storm water runoff [Pazwash, 2011]
and concentrations can be expected to be greater at a service station.] The greatest pollutant loads originate during
the "first flush" which occurs during the first inch of rainfall; loads will also increase with increasing time between
rain events.
8.1.2 Hydrogeological conditions
The sand units beneath the subject property are permeable, so that a subsurface release of petroleum product from
the UST system would migrate vertically until the ground water surface is encountered [Wiedemeier, 1999] at an
approximate depth of 12 to 27 feet [USGS, 2013].
Data collected in a study by Lawrence Livermore National Laboratories suggested that there was little apparent
Evaluation of the potential environmental impacts to ground water quality Page 29 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
relationship between hydrogeologic variables and the reported lengths of petroleum contaminant plumes [Rice et al.,
1995]. The study considered variations in ground water depth, range in fluctuation of the ground water surface, sand
and gravel thickness, free product thickness and ground water flow velocity. These findings have also been observed
in a similar study in Texas [Mace et al., 1997].
8.1.3 Contaminants released to ground water and surface water
The routine operation of gasoline service stations tends to produce greater pollutant concentrations than other urban
runoff. Common pollutant sources include gasoline spills, leaks of engine oil and hydraulic fluids, and dry
deposition of automobile exhaust. These materials accumulate on the ground surface until the time they are flushed
by rainfall into the storm sewer system. While underground storage tank systems are designed to be leak-proof, UST
systems often do leak and it is reasonable to assume that a leaking system at this site presents a real risk.
Petroleum products such as gasoline and diesel fuel are comprised of hundreds of compounds, each with differing
environmental and toxicological characteristics. BTEX compounds are among the lightest and are in greater
concentration in gasoline; while polynuclear aromatic hydrocarbons (PAHs) are heavier and are in greater
concentrations in diesel fuels.
BTEX and PAH constituents may cause health problems after repeated, high-level exposures. Benzene constitutes
0.12 to 3.50% of gasoline by weight [Sullivan, 2001]. The Department of Health and Human Services and the U.S.
EPA have determined that benzene is a known carcinogen. Although the health effects that may result from drinking
liquids containing lower levels of benzene are not known, drinking liquids containing high levels of benzene can
cause sickness, coma and death [ATSDR, 2007].
The Department of Health and Human Services and the International Agency for Research on Cancer have classified
various PAHs as carcinogenic, whereas the U.S. EPA has determined that some PAHs are probable carcinogens
while others are not classifiable as to human carcinogenicity [ATSDR, 1995]. For modeling exposure risks, IDEM
requires 12 PAHs36
Storm water runoff from service stations can contain relatively high concentrations of heavy metals, some of which
are toxic when present at sufficient concentrations. The metals cadmium, chromium, nickel, and lead can be
generated by the normal wear of bearings, bushings, moving engines parts, brake pad wear, tire wear and the
corrosion of galvanized metal components [Mijangos-Montiel et al., 2010].
to be evaluated for their carcinogenic properties [IDEM, 2013c].
The environmental fate of released pollutants will be significantly different for materials released to the subsurface
versus those released to the ground surface.
8.1.3.1 Ground water
The environmental fate petroleum released to the subsurface will be determined by the physical and chemical
properties of the released contaminant and the hydrogeologic media through which it travels.
Because petroleum is lighter than water, it would form a flattened pool atop the ground water surface. Variations in
the elevation of the ground water surface due to pumping and/or fluctuating recharge will move the floating product
up and down, creating a petroleum smear zone. Small droplets of petroleum will be entrained in the pores of the
aquifer material within this smear zone [U.S. EPA, 1989]. As the product and ground water remain in contact at the
boundary of the floating layer and in water-submerged droplets in the smear zone, the petroleum constituents will
begin to dissolve and will result in the contamination of ground water. Once dissolved, the dissolved contaminants
36 these are acenaphthene, acenaphthylene, anthracene, benz[a]anthracene, benzo [j]fluoranthene, benzo[a]pyrene, benzo[b]fluoranthene,
benzo[k]fluoranthene, chrysene, dibenz[a,h]anthracene, dibenzo(a,e)pyrene, dimethylbenz(a)anthracene, indeno[ 1,2,3-c,d]pyrene, 1-
methylnaphthalene, naphthalene, and 4-nitropyrene.
Evaluation of the potential environmental impacts to ground water quality Page 30 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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will flow offsite along with the prevailing ground water flow patterns.
The amount of petroleum that was released and the rates of petroleum degradation by indigenous microorganisms in
the aquifer were identified as the key variables that correlated with the ultimate length, concentration and lifespan of
a petroleum contaminant plume [Mace et al., 1997].
Multiple studies of leaking UST sites have found that the lengths of petroleum plumes will tend to stabilize over
time. Biological processes are often very important in the degradation of petroleum compounds, and can oftentimes
be achieved by indigenous microorganisms under a process known as natural attenuation [Wiedemeier, 1999]. It has
been noted that contaminant concentrations are diminished more rapidly than the plume lengths [Rice et al., 1995]. If
the contaminated soil above the water table is significantly reduced or removed, the plume mass will likely be
reduced through passive bioremediation, even if no active remediation is being performed [Newell and Connor,
1998].
8.1.3.2 Surface water
Because BTEX compounds are volatile, they readily evaporate to the atmosphere. This is especially rapid on
pavement surfaces and in free water surface wetlands. Biodegradation of BTEX compounds may also occur, as can
the removal of the compounds by plant uptake [Kadlec, 2009]. In the absence of water, the BTEX constituents may
partition to organic materials in the bottom of a wetland basin.
PAHs and heavy metals will accumulate at a gas station and become a potential pollutant source. The metals will
preferentially bind to small particles of soil that contain clay or have surface coatings of oxide or hydroxide 37
PAHs and metals are not volatile
, and
organic matter such as plant debris or peat [Miller, 2007]. Storm water will flush these particles from the facility.
The storm water BMPs will remove some of this material from the runoff and the remainder will flow to the
treatment pond or retention basin.
38
8.2 HUMAN & ENVIRONMENTAL EXPOSURE
and no loss to the atmosphere is anticipated in wetland conditions. PAHs are
more resistant to biodegradation than BTEX compounds, though some bacteria that can achieve 100% PAH
degradation. Free PAH compounds and metals reaching a wet or dry basin will partition strongly to organic
substrates and soils and have low solubility in water. PAHs are not taken up by wetland plants to any significant
extent [Kadlec, 2009]. Therefore, PAH compounds and metals will be persistent in the environment and will be
stored primarily in the sediments and organic matter.
A release can only cause human health effects if persons come into contact with the released material. If there is no
exposure, such as from dermal contact, inhalation or ingestion, then there is little chance of adverse health effects.
Spills to the ground surface provide the greatest risks of human exposure through dermal contact, accidental
ingestion, or inhalation of volatile fumes. Surface contact could also occur during the maintenance and cleaning of
the UST system and the storm water BMP. Sediment accumulations within a retention pond or basin will provide an
opportunity for direct human contact and for environmental exposure.
Contact with or ingestion of drinking water from wells is the primary route of human exposure to petroleum
products that have contaminated the aquifer. The subject property is within 1,000 feet of four residential wells
[IDNR, 2013] and is within the 1-year TOT of the wellhead protection area for Citizens Energy Group [CEG, 2013].
The operation of the CEG wells will likely cause ground water beneath the subject property to flow to the north or
northwest, in the direction of the residential wells (see Section 5.2.2).
37 these occur naturally. 38 Elemental mercury is volatile but is not anticipated to occur at a gas station, although other forms of mercury may be present.
Evaluation of the potential environmental impacts to ground water quality Page 31 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
Ricker's has presented data from a study to suggest that contaminant plumes resulting from leaking USTs will extend
only a few hundred feet. The study included a data from four separate studies of releases from leaking tanks, and an
evaluation of the composited statistics [Newell and Connor, 1998]. The suggestion presented by Ricker's was
factually true, that the average plume length 39
1. Plume lengths reported in three of the four separate studies [API, 1989; Rice et al., 1995; GSI, 1997] and in
the composited statistics [Newell and Connor, 1998] have lengths greater than 1,040 feet, which is the
approximate distance to the nearest CEG well and is greater than the distance to four residential supply
wells.
reported in the study was 132 feet and the greatest average plume
length was 213 feet [API, 1989]. Our evaluation of the same data abstracted from the source document has indicated
a few important points of consideration. Refer to Figure 3 when reviewing the following points:
2. All of the plume lengths reported in the four separate studies and in the composited statistics have lengths
greater than 350 feet, which is the approximate distance to the nearest residential supply well.
3. Two of the studies [Rice et al., 1995; Mace et al., 1997] used a value of 10 ppb40
Human exposure to petroleum products may be possible within the constructed retail building at the subject property
via vapor intrusion processes. Because gasoline constituents such as BTEX are volatile, they will form vapors in the
subsurface and will migrate through permeable soils. At the subject property, the shallow aquifer sand will underlie
less-permeable surface soil and site pavements, so that the vapors may concentrate and move along lines of least
resistance. If these vapors intrude the retail building, it is a possibility that persons inside would be exposed to
inhalation of BTEX vapors.
benzene to delineate the
edges of the contaminant plumes. One study [GSI, 1997] used values of 1 to 50 ppb while the remaining
study [API, 1989] did not indicate any criteria for measuring plume lengths. However, the Maximum
Contaminant Level for benzene is 5 ppb; this is the U.S. EPA treatment standard for public drinking water
supplies. Therefore, plume lengths based on a < 10 ppb will be underestimated for the purpose of the
protection of public health.
9 DISCUSSION OF FINDINGS
The presence of a gas station will pose risks related to the delivery, storage and dispensing of petroleum fuels. These
risks range from persistent, low-volume spills up to a catastrophic release of thousands of gallons of fuel, either
above-ground or below-ground. Carmel cannot assume that the existing state regulatory structure will provide
adequate protections.
The greatest protection from contamination is to have no gas station at the subject property; there is no remedy that
approaches this level of safety. If a gas station is to be constructed and operated there, the complete and reliable
containment of spilled product is the most important element in the protection of the ground water resources beneath
the facility. The use of a subsurface vault is by far the most protective and failsafe measure available.
9.1 THE AQUIFER IS VULNERABLE TO CONTAMINATION
Three factors influence the vulnerability of ground water resources to contamination. These are (1) the presence of
contaminant sources, (2) the combination of physical and chemical processes in the subsurface which affect
contaminant concentrations in an aquifer; and (3) the ease with which water and contaminants can travel to and
through an aquifer.
39 The plume length is the distance from the leaking UST(s) to the most distant point of contaminated ground water. 40 ppb = parts per billion = micrograms per liter = ug/L.
Evaluation of the potential environmental impacts to ground water quality Page 32 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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Danville, Indiana 46122-0681 XenonGeosci.com
Factor (1) is the only factor that does not exist at the subject property today; the subject property does not presently
pose a risk to the ground water resources. That would immediately change with the operation of a gas station at the
site; all three factors would be present and the ground water resources would become vulnerable. The delivery,
storage and dispensing of petroleum fuels presents significant risks. While there is certainty that petroleum will be
spilled onto the ground surface, the risk of a release from a UST system is significant: there are 17,000 entries in the
leaking UST database, 623 of which are in wellhead protection areas. Therefore, the absence of a gas station (or any
other facility that stores and handles products that could contaminate ground water) is the most protective measure
available.
Factor (2) refers to characteristics of the aquifer system such as the distribution of permeable versus impermeable
sediments or the presence of indigenous microorganisms that can digest petroleum compounds and thereby diminish
the contaminant concentrations. These variables are largely predetermined but they can be manipulated. Such
manipulation is technically challenging, expensive, uncertain, and takes a long time. Consequently, these measures
are not employed until a release has already occurred and contamination is confirmed. The horse has already left the
barn.
Factor (3) refers to the ability of released product to reach ground water. Sand deposits occur at a depth of five feet
below the ground surface and permeable deposits extend to the depth of the ground water table, so the ability for
contamination exists today. This is the one factor that must be altered to protect the ground water aquifer in the case
that a gas station is constructed. There is a variety of containment barriers that are on the market each with varying
levels of certainty of performance. Because failures of these protections will put the aquifer at risk of contamination,
a system that will perform reliably over the lifespan of the gas station must be selected.
The best possible containment protection would be achieved by the installation of a vault which contains the USTs
and associated piping. A vault is the only containment system that provides opportunity for visual inspection and
allows immediate containment and recovery of released product. A vault will provide failsafe protection in the
instance of failed release detection, and has the additional advantages of being able to be maintained while the
facility is in operation and its protective liner can be altered if need to assure material compatibility with future fuel
additives.
The installation of a UST tank and piping in accordance with the regulatory requirements does not assure that the
system will not release petroleum to the aquifer. While the barriers are effective when properly installed and
maintained, evidence suggests that installation issues and operational failures have become the most significant
source of failures from UST systems.
1. The installation of UST release detection equipment in accordance with the regulatory requirements does
not assure that the released petroleum will be detected. Various detection methods are available, but a
system can release 70 gallons/month or more and still be considered compliant.
2. The integrity of a UST system can be degraded over time. Although a UST system may have a high
integrity at the time it is installed, that integrity will be diminished as system components wear or become
damaged. Routine service and maintenance provides additional opportunities for failures due to
mechanical failure, faulty workmanship or human error.
3. A UST system designed for a particular fuel may not be compatible with differing amounts or types of
fuel additives. There is a large body of research that demonstrates that tanks, piping and other
components may be compatible with increased amounts of ethanol, but other components are not.
4. Although a UST system may have a high integrity at the time it is installed, that integrity can be breached
in an instant by human fallibility. Current UST regulations require intrusive sampling from areas where
Evaluation of the potential environmental impacts to ground water quality Page 33 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
Figure 3: Summary of plume lengths from various studies.
Evaluation of the potential environmental impacts to ground water quality Page 34 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
contamination is most likely to be present, and this can reasonably be understood as the vicinity of the
UST, piping and dispensers. IDEM recommends that samples be collected from at least 14 borings in
each 0.5-acre source area, creating a probability of accident that is not insignificant.
5. Regulations allow for a significant lag from the time a release is discovered and the time corrective
actions are implemented. There are no strict deadlines for completing investigative reports and plans that
culminate in the implementation of corrective actions. Throughout this investigation and reporting
process, it must be assumed that the leaked contaminant will continue to move through the subsurface.
9.1.1 Limitations of storm water regulations
The requirements of Rule 5 regarding the identification of potential pollutants during and following the completion
of construction activities are not sufficiently protective of releases to ground surface that could affect ground water.
The phrasing of the rule is that "...the plan... must include... a description of potential pollutant sources... that may
be reasonably be expected to add a significant amount of pollutants to storm water discharges
Rule 6, which applies to the operation of industrial facilities explicitly exempts automotive service stations and
convenience stores from regulation. Therefore, the operation of gas station would not be regulated under the NPDES
beyond the point that the construction permit is terminated.
. (Xenon's emphasis)"
This leaves open the possibility that potential pollutant sources that may be reasonably be expected to soak into the
site soils.
9.1.2 Limitations of spill reporting, containment and response
Spill reporting, containment and response rules establish the requirements to report spills of petroleum and
hazardous materials. The rule sets threshold quantities of these materials above which spill reporting requirements
apply. For areas within wellhead protection areas, the reportable quantities include spills of petroleum only when the
amount spilled exceeds fifty-five (55) gallons.
9.2 PROTECTIONS MUST BE BUILT IN FROM THE START
It is important that all storm water protective structures, including a retention pond if used, must be installed at the
start of construction operations to minimize the impact of accidental releases during construction. Fuel for heavy
equipment must not be staged at the site during construction.
If a bioretention pond or detention basin is relied upon for storm water treatment and/or spill containment, it is
imperative that they are owned and maintained by the owner of the gas station. The owner will need to be control
unrelated discharges to the structures so that they perform as designed and maintain adequate capacity to contain
spills. The owner will require unlimited access for emergency scenarios and routine maintenance operations.
The design of any ground water wells that are to be used for leak detection will need to anticipate fluctuations in the
ground water elevations under varying pumping conditions. This will require analytical or numerical modeling to
evaluate the amount of drawdown that would result from the operation of various wells, including the two wells
owned by the City of Carmel on the Legacy property and adjoining wellfields operated by Citizens Energy Group
and other community public water supply systems.
A Ground Water Protection Plan is needed to assure that all aspects of site operations are performed with the goal of
maintaining the protection of the ground water resources. Site employees must be trained in spill response
procedures and the operation of storm water BMPs, and have the awareness to recognize when protective measures
are damaged or otherwise prevented from proper functioning.
Evaluation of the potential environmental impacts to ground water quality Page 35 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
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9.3 FUTURE USE OF FUEL ADDITIVES MAY RESULT IN RELEASES
Ethanol- compatible equipment is presently available for today's fuel blends. Future federal mandates may change
the amount of ethanol in the fuel or result in additional or different additives with unknown compatibilities with the
equipment in place at the time. Not only must material incompatibilities be addressed at the time of initial
installation of a system, it will be an enduring requirement for future service, maintenance and upgrade activities.
This introduces uncertain risks associated with the accidental or unintended use of incompatible components and
seals which could result in the release of petroleum to the near-surface sand units and the underlying aquifer
materials.
9.4 DO NOT ASSUME CONTAMINANT PLUMES WILL EXTEND ONLY 200 FEET
Data has been presented by others which suggest that contaminated ground water plumes from leaking underground
storage tanks will extend only a few hundred feet. The information presented was a true statement of the findings of
a study performed by others: statistics indicated that the average length of contaminant (benzene) plumes for four
groups of leaking UST sites extended from 90 to 213 feet from the UST; and that when all sites were composited,
the average plume length was 132 feet. However, the rest of the story was not presented. The maximum plume
length of all sites extended far enough to reach the nearest residential wells. Indeed, with the exception of one group,
the maximum plume lengths extended far enough to reach the nearest municipal supply well and four residential
wells.
The plume lengths themselves cannot be directly used to evaluate ground water safety. The present drinking water
standard for benzene is 5 ppb. Two of the four groups of sites used 10 ppb to define the extent of the plume and one
group used a range of 1 to 50 ppb. No benzene criterion was given for the remaining group of sites. Consequently,
the plume lengths are under-represented in terms of contaminant levels that are permissible for consumption.
9.5 EXPECT CLEANUP OF THE AQUIFER TO BE SLOW AND DIFFICULT
In the event that the aquifer does become contaminated, the remediation of the ground water will be slow and
difficult. Although technologies have improved, the removal of contaminants from an aquifer is technically
challenging and requires investigation prior to implementation. IDEM sets a framework for the design and
implementation of corrective measures that can take years to complete (while still maintaining compliance).
The discovery of a release may not be immediate, providing time for the released product to migrate off-site. Ground
water is likely to flow from the subject property toward the north and northwest under the influence of pumping by
other municipalities. A contaminant plume would be expected to flow beneath 146th Street where the installation of
product recovery wells would be difficult.
10 RECOMMENDATIONS
Xenon has evaluated the potential environmental impacts to ground water quality which could result from the future
operation of a retail gas station at the southwestern corner of 146th Street and River Road. Although it was prepared
at the time of a development proposal for a service station by Ricker Oil Company, this evaluation is not intended to
address specific elements which have been submitted on Ricker's behalf. Our recommendations will apply to any
proposal for the operation of any retail gasoline station.
In anticipation that some parties may read only this section, we will reiterate a key statement made elsewhere in this
report: the absence of a gas station is the most protective measure available for the protection of the ground water
resources beneath the subject property. No engineered system will provide the same protections as the absence of
high-risk activities.
Evaluation of the potential environmental impacts to ground water quality Page 36 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
Our recommendations are as follows:
Recommendation 1: All petroleum storage tanks, piping and ancillary, below-grade equipment must be
placed in a constructed vault or similarly protective structure.
A vault will provide a high level protection. Similarly protective structures would need to be lined and
provide for visual inspections, the immediate removal of released product, and allow liner maintenance and
modifications as needed by wear or fuel additive compatibility requirements. Vaults and similar structures
offer failsafe protection against releases that are not detected by monitoring systems. The vault or structure
must contain release detection sensors (vapor and liquid product) and be inspected on a periodic schedule.
The release detection sensors should provide continuous data streams that can be accessed via the internet is
recommended.
Recommendation 2: The paved area beneath the canopy should drain to a vault or similarly protective
structure.
A vault should be constructed to contain runoff from the area beneath the canopy. Similarly protective
structures also provide protection against excessive overflows and spillage and capture the majority of
contaminants associated with the operation of a gas station. All pavements outside the canopied area are to
be graded to drain away from the canopied area.
Recommendation 3: The City of Carmel should not assume that the release detection requirements allowed
by regulation are adequately protective of the ground water resources.
The release detection regulations theoretically allow a release of 70 gallons per month or more to continue
without detection.
Recommendation 4: A release monitoring and detection plan must be developed prior to issuance of permit.
The applicant must provide a release monitoring and detection plan for the UST system and strategic storm
water structures. The plan must discuss the number and types of sensors to be deployed, their locations, and
possible issues of instrument calibration and false positive or false negative issues. The plan must also
outline the sampling frequencies for the various monitoring and detection points.
The applicant must properly design a tank pit or tank vault monitoring system and provide documentation
for their designs. Monitoring wells are commonly used as leak detection devices for monitoring the UST
tank pits, and were proposed for use by both Turkey Hill [DZE, 2010] and Ricker's [Creek Run, 2013]. Both
submittals located the tank pit well at a low position in the tank pit, with the presumption that leaked fluids
will flow down-slope to the well screen. Native soils at the subject property are sufficiently permeable that
spilled fluids may infiltrate the soil before reaching the tank pit monitoring well.
The applicant must properly design ground water monitoring well system and provide documentation for
their designs. They will need to accommodate potentially significant ground water fluctuations that could
occur during times of heavy ground water withdrawal from present-day and/or future well operations, and
during potentially extreme periods of low ground water recharge. A monitoring program for the well system
must be established on a monthly basis. The City of Carmel should have access to all monitoring data and
spill/incident reports as they request. The availability of an on-line vapor monitoring database should be
discussed.
Recommendation 5: Site designs must include a dedicated, properly designed bioretention pond or
containment basin that is owned and maintained by the gas station owner.
Evaluation of the potential environmental impacts to ground water quality Page 37 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
The purpose of the pond/basin is to provide treatment of persistent, low-volume spills from daily site
operations and to be a reservoir in the instance of a catastrophic release to the ground surface. The basin
must be installed at the same time as the other BMP components at the facility.
The pond/basin must have a synthetic liner capable of complete prevention of percolation to the underlying
soils. The liner must be demonstrated to be compatible with present-day fuels and possible high-ethanol
blends and biodiesel products.
Valves must be placed both upstream and downstream of the pond/basin to allow positive flow control in
the event of catastrophic releases. The outlet structure should have a submerged, down-ward curved pipe to
prevent floating product from discharging through the pipe.
Sediment from the subject property will accumulate in the retention basin and may contain contaminant
concentrations that exceed criteria established by IDEM. This sediment must not be disposed on-site unless
tested by a laboratory favorable with favorable results. The retention basin should be designed to allow
access for removal of accumulated sediments. This includes the routine access to remove sediment from the
area around the inlet pipe by a small crew with a shovel and cart, and to allow access by heavy equipment
for removal of accumulated sediments from the floor of the basin.
Recommendation 6: All storm water components must protect against the release of pollutants to the
subsurface.
The applicant must demonstrate a means of preventing the release of storm water to the subsurface,
including prevention of leaks at structure seals and joints, over the lifetime of their operation. The storm
water system must be capable of containing 110% of the largest possible spill during wet or snowy weather.
System maintenance procedures and schedules must be presented.
The applicant must demonstrate how they will retain control over all aspects of the storm water BMPs. This
includes measures to prevent runoff from other properties from degrading the performance or control over
storm water structures, piping and the treatment pond or retention basin.
Recommendation 7: A release response plan must be submitted for review prior to issuance of permit.
The applicant must provide a release response plan that establishes their plan of action in the event of a
release to the subsurface. The plan must consider both a long-term, undetected release of 70 gallons of fuel
per month, as well as a catastrophic release due from the largest proposed UST. An evaluation of the rate of
contaminant migration and travel-times to potential receptors must be performed. The plan must include a
schedule of reporting, notifications, confirmation, and product recovery actions that would occur under this
scenario. A discussion of the limitations, if any, posed by the presence of 146th Street must be given. The
plan must include documentation of calculations, design criteria, and assumptions; submittal of numerical
and/or digital media is appropriate.
Recommendation 8: All materials must be compatible with petroleum fuels, in perpetuity.
The applicant must provide documentation that each and all materials (UST system components, storm
water components, liners, etc.) that are relied upon for protection of the ground water aquifer are compatible
with today's fuel blends and with probable future use of E85 and biodiesel. The applicant must demonstrate
their understanding that material incompatibilities must be addressed at the time of initial installation of a
system, and that it will be an enduring requirement for future service, maintenance and upgrade activities.
Recommendation 9: Decrease the reportable spills quantity.
Evaluation of the potential environmental impacts to ground water quality Page 38 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
The reportable spill quantities allowed by water quality and UST regulations are not adequately protective
of the ground water resources due to the permeable nature of the near-surface sand units which immediately
overlie the aquifer materials. We suggest that the City of Carmel should require the owner/operator of the
facility to notify the City of spills at quantities on the order of 3-gallons for petroleum and 0.5-pounds for
any hazardous or extremely hazardous materials.
Recommendation 10: Contract documents for construction must address site-specific issues of vulnerability
to ground water contamination.
A construction contractor may assume that all pollutant-related requirements are addressed in the SWPPP
Contract documents must explicitly state, whether in the SWPPP or elsewhere, that spills that could impair
storm water or ground water must be carefully managed. Fuel for heavy equipment must not be staged at the
site during construction.
Recommendation 11: Require a review of the Ground Water Protection Plan prior to issuing a construction
permit.
A Ground Water Protection Plan must be submitted for review and approval. The GWPP must demonstrate
an understanding of the hydrogeological conditions that render the ground water vulnerable to
contamination, the possible causes of spills and releases, including those that are persistent or sudden, small-
or large-volume, to the surface or subsurface.
Spill prevention, containment and countermeasures must be addressed; the use of dispersants must be
discussed. The Plan must include maintenance schedules for the BMPs that are specified in the design
drawings. A snow-removal plan must be discussed and snow storage areas shown.
The plan must include an outline of site-specific training to be received by all gas station employees.
The plan should address how the owner will manage the risks associated with the use of UST system or
BMP components (tanks, pipes, liners, seals, etc.) that are no longer compatible with fuel blends as federal
mandates change over time.
Evaluation of the potential environmental impacts to ground water quality Page 39 of 43
which could result from the future operation of a retail gas station
at the southwestern corner of 146th Street and River Road, City of Carmel, Indiana
Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
Danville, Indiana 46122-0681 XenonGeosci.com
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Xenon Geosciences, Inc. Phone 317-745-0002
95 N Tennessee Street, Suite 10 Cell: 317-626-0600
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95 N Tennessee Street, Suite 10 Cell: 317-626-0600
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