MTBE REGULATIONS

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MTBE REGULATIONS

• Colorado Department of Labor and Employment
• Division of Oil and Public Safety

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Overview

• Oxygenate Usage
• MTBE Groundwater, Surface Water, and Receptor
  Impacts
• MTBE Aesthetic/Health Based Threats
• MTBE National Standards
• Colorado MTBE Phase Out
• OPS MTBE Regulations/MTBE Regulation
  Applicability

3
Bobby Sonnier

• Physical and Chemical Properties of MTBE
• Other Fuel Oxygenates and Breakdown Products of
  MTBE
• MTBE Exposure Pathway
• MTBE Points of Exposure (POEs)
• MTBE Point of Compliance (POC)

4
Mike Kwiecinski

• MTBE Laboratory Analytical
• Initial MTBE Analysis
• MTBE Receptor Survey
• Initial Reporting

5
Greg JohnsonDawn Anderson

• Prioritizing MTBE Investigations
• Priority Classification I
• Priority Classification II
• Priority Classification III

6
Jennifer SteffesJohn Gould

• MTBE Site Assessment
• Detailed Assessment Priority Classification I
  sites
• Standard Assessment Priority Classification II
  sites
• Limited Assessment Priority Classification III
  sites
• MTBE Remediation
• MTBE Pathway Elimination

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Overview
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Oxygenate Usage to Improve Vehicle Efficiency

• Late 1970s and 1980s
• Lead phase-out requirements
• Oxygenates Used
• MTBE
• Ethanol
• Methanol
• ETBE
• TAME
• DIPE
• TBA

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Required Oxygenate Usage to Reduce Air Emissions
and Smog

• 1987 Colorado Air Quality Commission adopted
  first regulations for Colorado Front Range
• 1990 Clean Air Act Amendments for U.S. regions
  where ozone or carbon monoxide exceeded air
  quality standards
• 1992 National Winter Oxygenated Fuel Program for
  40 U.S. metropolitan areas
• 1995 National Year-Round Reformulated Gasoline
  Program for 28 U.S. metropolitan areas

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Oxygenated Fuel Requirements

• 2.7 oxygen by weight in gasoline
• 15 by volume MTBE
• 7.3 by volume ethanol

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MTBE in Surface Water and Groundwater

• Large Scale Use
• High Concentrations
• High Solubility
• High Mobility
• Persistent

12
MTBE Prevalence in Colorado Groundwater

• 2003 - OPS RSIP collected split samples from
  sites that had been reimbursed from PSTF
  gt100,000
• 214 monitoring wells sampled
• 135 detectable concentrations of MTBE (63)
• 103 detections of MTBE gt 20 micrograms per liter
  (µg/L) (48)

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Impacts to Receptors

• Numerous impacts to water supplies throughout the
  U.S. including Lake Tahoe
• Lawsuits and cleanups costing millions of dollars
• Impacted private wells in Colorado

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EPA MTBE Drinking Water Advisory

• 20 to 40 µg/L of MTBE
• Will probably not cause unpleasant taste or odor
  for most people

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Petroleum Equipment Institute Tulsa Letter (July
27, 2005)

• The Environmental Protection Agency (EPA) has
  developed a draft risk assessment that concludes
  methyl tertiary butyl ether (MTBE) is a "likely"
  human carcinogen. The study pinpoints kidney and
  lymph node tumors as the result of MTBE exposure.
• The draft findings are currently undergoing
  review by EPA's waste, water, toxics, and air
  offices, which must file comments by August 15.

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MTBE National Standards

• gt 40 states have developed Drinking
  Water/Groundwater Standards, Action Levels and
  Guidelines
• Aesthetic criteria based on EPA advisory
• Health Based criteria based on toxicological or
  carcinogenic risk

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MTBE Phase Out

• On March 1, 2000 the Colorado legislature ordered
  the phase-out of MTBE as a fuel component or
  additive by April 30, 2002
• This legislation declared that it is the intent
  of the general assemblyto halt further
  contamination and pollution of this states
  groundwater supplies by MTBE

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OPS MTBE Regulations

• Effective May 30, 2005
• Based on EPA taste and odor criteria
• Ground water ingestion pathway only
• Risk-based screening level (RBSL) 20 µg/L

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MTBE Regulation Applicability

• All sites that are active when regulations
  promulgated
• All future release discoveries
• Sites where water supply wells and/or surface
  water features are determined to be impacted by
  MTBE that have previously received No Further
  Action

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Physical and Chemical Properties of MTBE
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Critical Physical and Chemical Properties
Influencing the Behavior of MTBE

• Solubility
• Adsorption
• Retardation
• Vapor Pressure
• Henrys Law Constant

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Solubility

• Solubility is the measure of a compounds ability
  to dissolve in water
• MTBE solubility in water is 50,000 mg/L
• Roughly 30 times more soluble than benzene
• Concentrations of MTBE can be much higher than
  benzene in groundwater

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Adsorption

• Defined as the tendency of dissolved compounds in
  groundwater to partition onto soil particles
• Degree of adsorption is directly proportional to
  the chemical-specific carbon partition
  co-efficient (Koc)
• Usually expressed as the log of Koc. The range of
  log Koc values are significantly lower for MTBE
  than for benzene, indicating MTBEs relatively
  low tendency to adsorb
• MTBE will not readily adhere to soil

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Retardation

• Retardation rate (R) Rate of movement (water)
  Rate of movement (contaminant)
• MTBE retardation rate (R) is close to 1.0,
  whereas the R for benzene is about 1.8
• MTBE will move at a rate similar to groundwater,
  resulting in a higher transport rate and longer
  plumes than for BTEX

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Vapor Pressure

• Measures the ability of a chemical to migrate
  from free product into the vapor phase
• The vapor pressure of MTBE is approximately three
  times greater than the vapor pressure of benzene
• MTBE has a relatively stronger tendency than
  benzene to volatilize from free product

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Henrys Law Constant

• Describes the partitioning of a compound from the
  dissolved phase to the vapor phase
• Henrys Law constants for BTEX constituents range
  from 0.22 to 0.35
• MTBEs relatively low Henrys Law constant
  (0.055) means relatively little MTBE will enter
  the vapor phase from the dissolved phase
• Remedial technologies involving contaminant
  transfer from dissolved to vapor phase (air
  sparging or stripping) will require higher air to
  water ratios for MTBE removal than for BTEX
  removal

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Comparison of Key Physical and Chemical
CharacteristicsBenzene and MTBE
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Other Fuel Oxygenates and Breakdown Products of
MTBE

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Alcohol

• Tertiary butyl alcohol (TBA)
• By-product of MTBE production
• By-product of MTBE degradation
• OPS encourages analysis, particularly if
  remediation strategies are being evaluated

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Ethers

• Oxygenates added to gasoline
• Ethyl tertiary-butyl ether (ETBE)
• Tertiary-amyl methyl ether (TAME)
• Diisopropyl ether (DIPE)
• OPS encourages analysis, particularly if
  remediation strategies are being evaluated

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MTBE Exposure Pathway
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Applicable MTBE Exposure Pathway

• Groundwater ingestion is the only exposure
  pathway considered to be a concern for MTBE

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Not Applicable MTBE Exposure Pathways

• Soil Leachate to Groundwater and Soil Vapor to
  Indoor Air
• MTBE does not readily sorb to soil particles
• Groundwater to Indoor Air
• Low Henrys Law coefficient, will not readily
  partition from the dissolved phase to the vapor
  phase
• Surficial Contact
• Aesthetic criteria

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MTBE Points of Exposure (POEs)
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POE Definition

• POE is the location at which a person or
  sensitive environment may be exposed to a
  chemical of concern (COC)
• Currently existing or planned to be developed
  within 5 years

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Applicable MTBE POEs

• Water supply wells used for human consumption
• Surface water features used for human consumption

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Not Applicable MTBE POEs

• Property boundary
• Surficial soils
• Utilities
• Structures
• Sensitive Environments
• Groundwater wells and surface water features that
  are not used for human consumption

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Surface Water Features With Water Withdrawn for
Human Consumption

• MTBE gt 20 ppb in groundwater adjacent to feature,
  feature must be sampled
• Pathway elimination if four quarters of
  monitoring indicate no potential for RBSL
  exceedences upgradient of the takeout location of
  the water used for human consumption

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MTBE RBSL Exceeded in Groundwater Adjacent to
Surface Water POE
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MTBE Point of Compliance (POC)
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Definition of POC

• Monitoring wells located
• Downgradient of the source area
• Beyond the limits of the defined extent of
  contamination
• Between the defined extent of contamination and
  any POEs

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POC for MTBE Plumes

• The POC should be located no closer than a
  one-year travel distance to the POE, if possible
• POC wells must be spaced such that contaminant
  migration will be detected across the leading
  edge of the plume, and POEs are protected

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Impacted POCs

• If POC concentrations exceed RBSLs
• Remediation must be performed to bring them into
  compliance or
• A new POC well must be installed downgradient
  (upon concurrence with OPS)

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Point of Compliance when POEs are Impacted

• POEs can not be considered POCs
• Following POE remediation, POCs must be installed
  beyond the limits of the MTBE contamination and
  upgradient of the POE

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Modeling and POCs

• Modeling should be used to estimate the placement
  and number of POC wells
• Modeling can not be used in lieu of the placement
  of POC wells

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POC Locations

• Sites may have two locations where compliance is
  required
• A location upgradient of the property boundary
  (BTEX compliance)
• A location upgradient of a water supply well or
  surface water feature used for human consumption
  (MTBE compliance)

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Compliance Requirement LocationsBenzene and MTBE
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MTBE Laboratory Analytical
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Method 8021GC/PID

• Method 8021 GC/PID may be used in conjunction
  with Method 8260 GC/MS verification at key
  locations
• Source monitoring well (at sites where no MTBE is
  detected)
• POC wells (in situations where POC wells have not
  yet been installed, the verification sampling
  will be performed on samples from the most
  downgradient monitoring well)
• Monitoring well with highest concentration
• All impacted or potentially impacted POEs

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Method 8260 GC/MS

• Method 8260 GC/MS may be used in lieu of Method
  8021
• Costs are comparable if reporting is limited to
  BTEX and MTBE

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Why 8260 GC/MS Verification

• Method 8021 GC/PID may be susceptible to both
  false positives and false negatives
• 8260 GC/MS is more reliable in accurately
  quantifying MTBE than 8021 GC/PID

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Laboratory Analytical Methods for Alcohols and
Ethers

• Method 8260 GC/MS must be used if analyzing for
  TBA, TAME, ETBE and DIPE

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Initial MTBE Analysis

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Analytical Requirements

• MTBE analysis is required for all water samples
  collected at petroleum storage tank sites on or
  after May 30, 2005
• At sites with active events, sampling and
  analysis of MTBE must be performed within 3
  months of May 30, 2005

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MTBE Receptor Survey
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Receptor (POE) Data Collection

• All current and planned surface water features
  located downgradient and within 2,500 feet of the
  source
• All current and planned water supply wells
  located downgradient and with a radius of
  influence within 2,500 feet of the source

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Supply Well Detail Data Collection

• Pumping rate
• Well construction details, including
• Depth
• Diameter
• Screened interval
• Calculated radius of influence

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Screening Out Receptors

• All water supply wells and surface water features
  located downgradient of the source and lt 2,500
  feet must be identified and reported by November
  30, 2005
• OPS concurrence must be obtained in order to
  eliminate potential receptors

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Receptor Survey Resources

• Colorado Department of Natural Resources
• Local Planning and Zoning offices
• Local Water Boards
• Etc.

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Colorado Department of Natural Resources,
Division of Water Resources www.water.state.co.us
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State Engineer www.water.state.co.us/pubs/welldat
a.asp
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Local Zoningwww.co.jefferson.co.us/ext/dpt/public
_works/planning/general-info/how_to_reach/how-to-r
each-us.htm
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Initial Reporting
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MTBE Initial Reporting

• At existing sites MTBE concentrations and results
  of the receptor survey will be incorporated into
  the Quarterly Monitoring Report and submitted by
  November 30, 2005
• At new release sites MTBE concentrations and
  results of the receptor survey will be
  incorporated into the Site Characterization
  Report due within 90 days of the reported release

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Time Frame Summary
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MTBE Initial Reporting Requirements

• MTBE analytical
• Receptor information with recommendations
• Initial evaluation of whether the groundwater
  ingestion pathway is complete
• Initial determination of the appropriate Priority
  Classification

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1) Initial Reporting Requirements For MTBE
Analytical

• Table with historical MTBE concentrations
• Map with current MTBE concentrations

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2) Initial Reporting Requirements ForReceptor
Information

• A detailed map with attached table clearly
  identifying all water supply wells (including
  radius of influence) and surface water features
  located within 2,500 ft downgradient of the
  source
• Supply well completion diagrams
• A table listing details of each supply well
• Justification/documentation for the elimination
  of any potential POE located lt 2,500 feet from
  source

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3) Initial Reporting Requirements ForEvaluating
the Groundwater Ingestion Pathway

• MTBE Groundwater Ingestion Pathway is complete
• MTBE Groundwater Ingestion Pathway is not
  complete
• MTBE is not detected during quarterly groundwater
  sampling
• At least four consecutive quarters of MTBE
  laboratory data indicates concentrations are
  stable or declining, the extent of the
  contamination has been defined and it can be
  demonstrated that there are no threats to POEs
• OPS concurrence will be required after report
  review

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4) Initial Reporting Requirements for Determining
the Appropriate Priority Classification

• A Priority Classification, based upon the data
  collected at the time of the report submittal,
  must be selected
• Stay tuned to the next presentation for details
  concerning Priority Classifications..

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Prioritizing MTBE Investigations
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Priority Classifications

• There are 3 Priority Classifications, where
  Classification I has the most severe threats and
  Classification III has the least
• Sites are classified according to the potential
  threats to water supplies
• The initial site priority classification
  determination will consider only the distance to
  the POE

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Priority Classification I

• Impacted POE

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Priority Classification IPOE is Impacted
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Priority Classification I Requirements and Time
Frame
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Priority Classification II

• Existing or planned POE located lt 2,500 feet from
  source, AND
• Potential of impacts is unknown, OR
• Contamination has the potential to impact a POE

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Classification IIPotential of Impacts is
UnknownPlume is not defined
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Classification IIPotential of Impacts is
UnknownPlume is not stable or diminishing
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Priority Classification II

• Existing or planned POE located lt2,500 feet from
  source, AND
• Potential of impacts is unknown, OR
• Contamination has the potential to impact a POE

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Classification IIModeling Indicates MTBE gt 20
ppb will reach POE
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Priority Classification II Requirements and Time
Frame
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Priority Classification III

• Existing or planned POE located lt 2,500 feet from
  source, AND it has been demonstrated (with OPS
  concurrence) that contamination does not have
  potential to impact a POE, OR
• Existing or planned POE located gt 2,500 feet from
  source, AND modeling indicates that the plume
  WOULD migrate beyond 2,500 feet

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Classification IIIModeling indicates that MTBE gt
20 ppb will not reach POE
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Priority Classification III

• Existing or planned POE located lt 2,500 feet from
  source, AND it has been determined (with OPS
  concurrence) that contamination does not have
  potential to impact a POE, OR
• Existing or planned POE located gt 2,500 feet from
  source, AND modeling indicates that the plume
  WOULD migrate beyond 2,500 feet

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Classification IIIModeling indicates that MTBE gt
20ppb will reach 2,500 feet from source
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Priority Classification III Requirements and Time
Frame
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Moving Between Priority Classifications

• Example Classification II to I
• A POE, not initially impacted, becomes impacted
• Example Classification II to III
• The plume, not initially defined, is now defined
  and modeling indicates that the POE will not be
  impacted

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Time Frame Summary
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Time Frame Summary
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MTBE Site Assessment
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MTBE Site Assessment

• The level of effort required to assess MTBE
  contamination is dependant upon the Priority
  Classification determined for the site
• Each Priority Classification has a required
  assessment level

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Level of MTBE Assessment

• Detailed Assessment required at Priority
  Classification I sites
• Standard Assessment required at Priority
  Classification II sites
• Limited Assessment required at Priority
  Classification III sites

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Additional Tasks forMTBE Assessment Priority
Classifications I II

• Generate geologic cross-sections
• Define horizontal and vertical extent of MTBE
  plume
• Measure K and calculate GW velocity (vertical)
• Plot concentration vs. time for individual wells
• Plot concentration vs. distance for wells along
  the centerline of the plume
• Model potential migration to receptors using fate
  and transport modeling

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Additional Tasks for MTBE Assessment Priority
Classification III

• Define the horizontal extent of the MTBE plume
• Modeling to predict plume migration to a distance
  of 2,500 feet from the source

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Geologic Cross-Sections

• Cross-section should include all wells and/or
  soil borings along the axis of the plume in the
  direction of GW flow
• Represent the cross-section line on the site map
• Show screen intervals of wells
• Illustrate the water table elevation
• Label the lithologies encountered
• Identify zones of contamination (soil and GW)

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Vertical Plume Migration

• MTBE plumes in recharge areas tend to migrate
  downward (dive) during downgradient migration
• Active supply wells can draw plumes downward and
  affect lateral plume migration

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Definition of Vertical Extent

• Vertical extent of the MTBE plume must be
  defined if
• The POE is a supply well used for human
  consumption
• The plume is in a recharge area
• Other conditions at the site indicate that the
  plume may be diving
• Remediation of MTBE is required

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Vertical Extent Wells

• Determining monitor well screen depths
• Alluvial Environment
• A groundwater flow model should be used to
  determine screen placement in vertical extent
  monitoring wells
• Fractured Bedrock
• Since flow will follow fractures and not be
  predictable, appropriate screen placement may
  involve additional hydraulic and geophysical
  testing

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MTBE Concentration Data Evaluation

• The following graphs are required to assess plume
  migration and stability
• Concentration vs. Time
• Concentration vs. Distance
• The graphs can be produced using the tool
  provided on the OPS web site
• http//oil.cdle.state.co.us/OIL/Technical/MNA/

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Concentration vs. Time

• Requires four consecutive quarters of analytical
  data for the source well or downgradient plume
  well between the source and a POE

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Concentration vs. TimeExample Graph
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Concentration vs. Distance

• Requires analytical data for at least three
  contaminated wells, including source well, along
  the axis of the plume
• Requires site specific information
• Average hydraulic conductivity (K) (feet/day)
• Hydraulic gradient (i) (unitless)
• Soil bulk density (pb) (g/cm3)
• Effective porosity (ne) ()
• Fraction organic carbon (FOC) (unitless)

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Concentration vs. Distance Example Graph
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Modeling

• Fate Transport modeling is required to evaluate
  plume migration and potential impacts to
  receptors
• OPS encourages the use of modeling to determine
  the location and spacing of monitoring wells for
  horizontal and vertical plume definition
• Modeling without an actual POC well may not be
  used to determine the location where compliance
  is achieved
• Modeling may not be substituted for required site
  data

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MTBE Levels of Assessment
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Detailed Assessment

• Required for Priority Classification I Sites
• POE is impacted
• Requires highest level of effort

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Detailed Assessment
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Standard Assessment

• Required for Priority Classification II Sites
• Existing or planned POE located lt 2,500 feet from
  source, AND
• Potential of impacts is unknown, OR
• Contamination has potential to impact a POE

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Standard Assessment
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Limited Assessment

• Required for Priority Classification III Sites
• Existing or planned POE is located lt 2,500 feet
  from source, and it has been demonstrated (with
  OPS concurrence) that contamination does not have
  potential to impact a POE, OR
• Existing or planned POE is located gt 2,500 feet
  from source, and modeling indicates that the
  plume would migrate beyond 2,500 feet

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Limited Assessment
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MTBE Remediation
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Remediation of MTBE

• One or more POEs or POCs have been impacted by
  MTBE contamination exceeding 20 µg/L, or
• There is free product in groundwater or a soil
  source contributing to high concentrations of
  MTBE, or
• The plume is expanding and/or migrating, and
  there is a POE within 2,500 ft of the source, or
• Modeling indicates that a POE or a POC may become
  impacted, or
• Future use of an impacted water source has been
  planned

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Remedial Technologies for MTBE

• Links to remediation resources and website
  addresses are provided on the OPS website
  http//oil.cdle.state.co.us

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MTBE Pathway Elimination
122
Pathway Elimination

• MTBE concentrations are below 20 µg/L
• MTBE concentrations exceed 20 µg/L but the plume
  is defined, POC wells are below 20 µg/L, and
  modeling indicates that the POC well will not
  become impacted above 20 µg/L in the future
• There are no POEs located downgradient within
  2,500 ft of the source and modeling indicates
  that the plume will not migrate beyond 2,500 ft