groundwater rule workshop dec drinking water program september 22-23, 2009
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Slide 1
Groundwater Rule Workshop DEC Drinking Water ProgramSeptember 22-23, 2009
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Treatment Technique Requirements
Vanessa Wike, PE
Statewide Engineering Coordinator
DEC Drinking Water Program
vanessa.wike@alaska.gov
Topics
GWR Treatment Goal
When ? What?
Treatment Method Highlights (Virus Treatment)
Removal
Conventional/Direct Filtration/Slow Sand/Diatomaceous Earth
Alternative Filtration
Bag/Cartridge
Membrane
Inactivation
Ultraviolet Radiation (UV)
Ozone
Chloramines
Chlorine
Summary
2
Topics
GWR Treatment Goal
When ? What?
Treatment Method Highlights (Virus Treatment)
Removal
Conventional/Direct Filtration/Slow Sand/Diatomaceous Earth
Alternative Filtration
Bag/Cartridge
Membrane
Inactivation
Ultraviolet Radiation (UV)
Ozone
Chloramines
Chlorine
Summary
3
GWR Treatment Objective
4-Log Virus Treatment by Removal and/or Inactivation (4 Log = 99.99%)
PWS approved* for 4-log treatment is not required to conduct source water monitoring
* Must be formally awarded treatment credit through engineering plan approval.
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When is Treatment Required?
Risk Targeted Approach: The source is determined to be vulnerable or at a higher risk to contamination based on poor well construction or proximity to sources of fecal contamination; or
Triggered Approach: The water system has a history of fecal contamination.
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When is Treatment Required?
Risk Targeted Approach: The source is determined to be vulnerable or at a higher risk to contamination based on poor well construction or proximity to sources of fecal contamination; or
Triggered Approach: The water system has a history of fecal contamination.
Based on current sampling results, we are estimating that less than 5% of existing PWS using a groundwater source will be require treatment based on the triggered approach.
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What are Treatment Options?
Same treatment options , DEC review criteria and review process as is currently used.
Proposed treatment will be assessed with respect to effectiveness at 4 log virus removal.
Treatment Credit (new and existing PWSs)
Formally issued through DW engineering plan review.
Operational Certificate will specify treatment credit.
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Treatment Method Overview
Guidance & References
Treatment Credit Awarded
Major Selection Considerations/Plan Review Requirements
General Operation and Maintenance Considerations
Performance and Compliance Monitoring
Advantages and Disadvantages
Potential Applications for Large and Small Systems
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Treatment OptionsRemoval
Conventional/Direct Filtration/Slow Sand/Diatomaceous Earth
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Treatment Options Removal Conventional/Direct Filtration/Slow Sand/Diatomaceous Earth
Guidance / Reference(s)
SWTR Guidance Manual. EPA. March 1991
Treatment Credit
Monitoring/Reporting Requirements
Recommended Standards for Water Works
(aka 10 States Standards)
General Design Criteria
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Treatment Credit Virus (SWTR Guidance)
Conventional:2.0 Log
Direct:1.0 Log
Slow Sand:2.0 Log
Diatomaceous Earth:1.0 Log
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Treatment Options Removal Conventional/Direct Filtration/Slow Sand/Diatomaceous Earth
System Design Requirements
Conventional: Coagulation Sedimentation Flocculation Filtration Steps
Direct: Coagulation - Flocculation Filtration Steps
Slow Sand: Schmutzdecke, smaller grain size, no backwash, removal of surface media
Diatomaceous Earth: Pre-coat or Diatomite Media, no backwash, removal of surface media
Important Note for Filtration Classification - Media Type and Grading must meet 10 States Standards.
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Treatment Options Removal Conventional/Direct Filtration/Slow Sand/Diatomaceous Earth
Operation & Maintenance
Identical to Filtration under SWTR
High Operator Oversight
Water Demand
Raw Water Quality
Filter Backwash Cycles
Chemical Dosing
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Treatment Options Removal Conventional/Direct Filtration/Slow Sand/Diatomaceous Earth
Performance and Compliance
Same as SWTR Guidance
Filtration Performance
Turbidity Monitoring
Compliance Reporting
Note: Credit for virus removal is based on specified filter performance in SWTR Guidance.
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Treatment Options Removal Conventional/Direct Filtration/Slow Sand/Diatomaceous Earth
Advantages and Disadvantages
More disadvantages than advantages
Unlikely New Treatment Option:
High capitol cost
High O&M
Low treatment credit
Additional treatment required to meet 4 Log
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Treatment Options Removal Conventional/Direct Filtration/Slow Sand/Diatomaceous Earth
Potential Applications
Larger Systems
Existing filtration may be able to receive credit with:
Approval from Department
Modification likely required to add filtration steps (coagulant)
Media may need to be changed (10 States Standards)
Turbidity Monitoring would need to be added
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Treatment Options Removal Conventional/Direct Filtration/Slow Sand/Diatomaceous Earth
Treatment OptionsRemoval
Bag and Cartridge Filtration
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Bags & Cartridge Filtration
Does not include membrane-type cartridges
Not appropriate treatment for virus removal
Particle Filtration ability too course for virus removal
Finest particulate filtration is ~1 um
Virus size is ~0.1 um or less
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Treatment Options RemovalAlternative Filtration - Bag and Cartridge Filtration
Treatment OptionsRemoval
Membrane Filtration
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Guidance / Reference(s)
Membrane Filtration Guidance Manual. EPA. November 2005
Design
Treatment Credit
Challenge Testing
Monitoring/Reporting Requirements
GWR Corrective Action Guidance Manual (Draft). EPA. June 2008
Overview
Treatment Credit
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Treatment Options Removal Alternative Filtration - Membranes
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Membrane Filtration Types:
Microfiltration (MF)
Ultrafiltration (UF)
Nanofiltration (NF)
Reverse Osmosis (RO)
Type defined by range of removal and operating pressure.
Treatment Options Removal Alternative Filtration - Membranes
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Treatment Credit Virus (GWR Corrective Action Guidance)
Micro Filtration (MF):Not Appropriate
Ultra Filtration (UF):Challenge Test Dependent
Nano Filtration (NF):4.0 + Log *
Reverse Osmosis (RO):4.0 + Log *
*Treatment credits awarded based on challenge test results at State discretion. 3rd Party challenge test results will be required.
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Treatment Options Removal Alternative Filtration - Membranes
Coagulation may increase effectiveness of MF and UF
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Treatment Selection/Design Considerations
Validation / Challenge Testing
Raw water quality dependant
Added complexity to treatment system if pre-treatment is required Operator Certification Level
May increase corrosiveness of water Lead/Copper issues possible
Performance and compliance monitoring
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Treatment Options Removal Alternative Filtration - Membranes
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Product Validation - Challenge Testing
One time, product specific test completed for manufacturer by 3rd Party Lab
Verifies the maximum contaminant removal capability - basis for treatment credit
DW Program requires challenge test results of a device, using an approved protocol, before issuing credit
*Important* Most challenge tests do not use a surrogate representative of virus contaminants.
There are currently no validated membranes on the market eligible for 4-log removal credit of viruses (at this time).
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Treatment Options Removal Alternative Filtration - Membranes
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Operation & Maintenance
Generally follows EPA Membrane Filtration Guidance
Product-specific Operator Training
Membrane performance monitoring may be more stringent than compliance performance limits.
Direct Integrity Testing used to validate proper membrane function
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Treatment Options Removal Alternative Filtration - Membranes
Performance and Compliance
Monitoring Requirements (EPA Membrane Guidance)
Turbidity Monitoring Standard Alternate Filtration
Compliance Reporting
Direct Integrity Testing and Reporting
Indirect Integrity Testing (continuous turbidity)
Inactivation credit dependant on challenge test results
Challenge test review is extremely detailed and time consuming.
Recommend submitting challenge test report to DEC prior to unit selection.
Plan for extended plan review period due to multiple reviews and approval
Draft membrane monitoring and operator reporting forms have been developed. May be modified for system specific conditions.
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Treatment Options Removal Alternative Filtration - Membranes
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Treatment Options Removal Alternative Filtration - Membranes
Advantages
High effluent water quality
Compact installation
Relatively simple operation
Disadvantages
High installation cost
Performance and compliance monitoring
Operator certification level
Lead/Copper Issues
Potential Applications
Large Systems Requires healthy financial capacity or ample funding source due to high capitol cost.
Small Systems Unlikely option due to lack of product availability that meets challenge test protocol.
Operator expertise required. Specialized training beyond standard Operator Certification may be required.
** Point of Use / Point of Entry type membrane units are not approved for use for microbial treatment.
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Treatment Options Removal Alternative Filtration - Membranes
Treatment OptionsInactivation
Ultra-Violet Radiation
UV
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Guidance / Reference(s)
UV Disinfection Guidance Manual (UVDGM). EPA. November 2006
Design
Treatment Credit
Challenge Testing
Monitoring/Reporting Requirements
Note: This is the most comprehensive guidance for regulating UV treatment units available today.
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Treatment Options InactivationUltra-Violet Light (UV)
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Treatment Credit Virus
Inactivation credit dependant on challenge test results
Challenge test review is extremely detailed and time consuming.
Recommend submitting challenge test report to DEC prior to unit selection.
Plan for extended plan review period due to multiple reviews and approval.
** There are no UV units that have been approved in Alaska for inactivation credit of viruses.
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Treatment Options InactivationUltra-Violet Light (UV)
Treatment Selection/Design Considerations
Validation / Challenge Testing
Establishes design criteria and treatment credit
Raw water quality dependant 1 year of transmissivity data recommended
Added complexity to treatment system if pre-treatment is required Operator Certification Level
Design around UV unit must emulate validated conditions
Performance and compliance monitoring
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Treatment Options InactivationUltra-Violet Light (UV)
Operation & Maintenance
Follows UV Disinfection Guidance
High level of product-specific Operator Training
Added complexity to treatment system if pre-treatment is required
May reduce free chlorine concentration
Units must have specific monitoring capability
Relatively simple operation and maintenance
Maintenance is critical
High power consumption and quality requirements
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Treatment Options InactivationUltra-Violet Light (UV)
Performance and Compliance
Performance measures to follow EPA UV Guidance
Monitoring Requirements
Very unique to other treatment types - measurements of light intensity.
Compliance Reporting Monthly Operator Reports
** Draft UV monitoring and operator reporting forms have been developed for certain types of UV units.
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Treatment Options InactivationUltra-Violet Light (UV)
Treatment Options Inactivation Ultra-Violet Radiation (UV)
Advantages
High Crypto & Giardia Inactivation
No known DBP formation
Compact installation
Relatively simple operation
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Disadvantages
High dose for virus inactivation
Disinfection effectiveness difficult to monitor
UV lamps contain mercury
Power cost
Stable power source required
Potential Applications
Large Systems Unlikely due to capitol cost and high power requirements to meet virus inactivation in comparison to other options.
Small Systems Unlikely option (at this time) due to lack of product availability that meets challenge test protocol.
Operator expertise required. Specialized training beyond standard Operator Certification may be required.
Operator dedication required for routine maintenance for successful operation.
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Treatment Options InactivationUltra-Violet Light (UV)
Treatment OptionsInactivation
Ozone Disinfection
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Guidance / Reference(s)
SWTR Guidance Manual. EPA. March 1991
Treatment Credit
CT Table
Alternative Disinfectants and Oxidants Guidance Manual. EPA. April 1999
General Design Criteria
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Treatment Options InactivationOzone
Treatment Credit Virus
CT dependant on following:
Water temperature (Celsius)
Ozone residual concentration (mg/L)
0.5 Log to 4.0 log credit possible
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Treatment Options InactivationOzone
Treatment Options Inactivation Ozone Disinfection
Treatment Selection/Design Considerations
Seasonal water quality data to establish ozone demand, including: Fe, Mn, TOC.
Ozone unit output size critical. Unit is sized to highest ozone demand raw water quality.
Stable power source
Pretreatment may be necessary
Possible DBP formation if Bromide is present in raw water.
Contact tank volume size appropriately for system demand
Tank design to address short circuiting (baffle factor)
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Operation & Maintenance
Safety concerns for ozone off-gassing
High Operator Oversight
Venturi or injection port fouling
High wear parts replacement (electrodes)
Redundant system or back-up disinfection system recommended.
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Treatment Options InactivationOzone
Performance and Compliance
Similar to chlorine residual monitoring
CT verification based on established CT and daily ozone residual monitoring
Compliance Reporting
** Initial ozone monitoring and operator reporting forms have been developed.
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Treatment Options InactivationOzone
Potential Applications
May be a viable option for system with:
Year-around high water quality.
Stable power source
Dedicated operator
May not be financially justifiable compared to chlorination unless:
Foot print is limited
Chemical storage and/or access is limited
Chlorine taste is an issue
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Treatment Options InactivationOzone
Treatment OptionsInactivation
Chloramines
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Guidance / Reference(s)
Alternative Disinfectants and Oxidants Guidance Manual. EPA. April 1999
General discussion on virus inactivation
Potential Application
Generally not appropriate if virus inactivation is the sole treatment objective.
Chlorine dose required to meet CT is about an order of magnitude greater than standard chlorination.
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Treatment Options InactivationChloramines
Treatment OptionsInactivation
Chlorination
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Guidance / Reference(s)
SWTR Guidance Manual. EPA. March 1991
Treatment Credit
CT Table
Monitoring/Reporting
Alternative Disinfectants and Oxidants Guidance Manual. EPA. April 1999
Simultaneous Compliance Guidance Manual for the LT2 and Stage 2 DPB Rule. EPA. March 2007
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Treatment Options InactivationChlorine Disinfection
Treatment Credit Virus
CT dependant on following:
Water temperature (Celsius)
pH
Chlorine residual concentration (mg/L)
0.5 Log to 4.0 log credit possible
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Treatment Options InactivationChlorine Disinfection
Treatment Options Inactivation Chlorine Disinfection
Treatment Selection/Design Considerations
Contact tank volume size appropriately for system demand
Tank design to address short circuiting (baffle factor)
Possible DBP formation simultaneous compliance issue (suggest reading the guidance).
Potential safety issues addressed through design for gaseous chlorine/chlorine dioxide
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Performance and Compliance
Chlorine residual monitoring
CT verification based on established CT and daily chlorine residual monitoring
Compliance Reporting
** Chlorine monitoring and operator reporting forms have been developed for statewide use.
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Treatment Options InactivationChlorine Disinfection
Potential Applications
Most likely the most viable option for virus treatment for most systems.
Various types of media for chlorination.
Hypochlorite
Onsite chlorine generation from salt
Chlorine Gas
Chlorine Dioxide
The potential for DBP formation may be a concern.
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Treatment Options InactivationChlorine Disinfection
Summary
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Groundwater Rule Workshop DEC Drinking Water Program - September 22-23, 2009 Treatment Technique Requirements SummaryVanessa Wike, PE
Less than 5% of systems will be affected by this treatment component of this rule (rough estimate).
Proposed treatment will be reviewed in the same manner as is currently used using the treatment objective of 4 log virus removal.
Treatment Credit is formally issued through DEC DW Plan Review.
Operational Certificate will specify treatment credit.
Most systems required to treat are expected to select some form of chlorination.
Engineering Submittal Checklists available online at:
http://www.dec.state.ak.us/eh/dw/dwmain/engineering.html
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