groundwater rule workshop dec drinking water program september 22-23, 2009

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

[email protected]

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

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Topics

GWR Treatment Goal

When ? What?

Treatment Method Highlights (Virus Treatment)

Removal


Alternative Filtration

Bag/Cartridge

Membrane

Inactivation

Ultraviolet Radiation (UV)

Ozone

Chloramines

Chlorine

Summary

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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


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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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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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Operation & Maintenance

Identical to Filtration under SWTR

High Operator Oversight

Water Demand

Raw Water Quality

Filter Backwash Cycles

Chemical Dosing

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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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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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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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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


Membrane Filtration

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Membrane Filtration Guidance Manual. EPA. November 2005

Design

Treatment Credit

Challenge Testing


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.


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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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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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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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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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Monitoring Requirements (EPA Membrane Guidance)

Turbidity Monitoring Standard Alternate Filtration


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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Advantages

High effluent water quality

Compact installation

Relatively simple operation

Disadvantages

High installation cost


Operator certification level

Lead/Copper Issues


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 OptionsInactivation

Ultra-Violet Radiation

UV

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UV Disinfection Guidance Manual (UVDGM). EPA. November 2006

Design

Treatment Credit

Challenge Testing


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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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


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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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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 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


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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Ozone Disinfection

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Treatment Credit

CT Table

Alternative Disinfectants and Oxidants Guidance Manual. EPA. April 1999

General Design Criteria

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Treatment Options InactivationOzone


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 Inactivation Ozone Disinfection


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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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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Similar to chlorine residual monitoring

CT verification based on established CT and daily ozone residual monitoring


** Initial ozone monitoring and operator reporting forms have been developed.

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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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Chloramines

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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


Chlorination

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Treatment Credit

CT Table

Monitoring/Reporting


Simultaneous Compliance Guidance Manual for the LT2 and Stage 2 DPB Rule. EPA. March 2007

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Treatment Options InactivationChlorine Disinfection


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 Inactivation Chlorine Disinfection


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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Chlorine residual monitoring

CT verification based on established CT and daily chlorine residual monitoring


** Chlorine monitoring and operator reporting forms have been developed for statewide use.

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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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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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groundwater rule workshop dec drinking water program september 22-23, 2009

Documents

log treatment

proposed treatment

treatment credit new

log virus removal

water system

history of fecal contamination

source water monitoring

risk targeted approach