Deep Well Injection A Possible Solution for ... - Ohiowater.org

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Deep Well Injection A Possible Solution for ... - Ohiowater.org

Deep Well Injection:

A Possible Solution for

Membrane Reject Waste

Presented by:

Christopher Everett, CPG

Scott Dailey, CPG


Introduction

• Water treatment membranes are HOT

• However, membrane waste disposal is a

regulatory concern

– Future TDS discharge regulations likely to be

more restrictive

– Only guidelines exist at this time, making future

planning a challenge


Introduction

• Is there an alternative for membrane waste

disposal?


Advantages of Membrane Treatment

• Ability to remove micro-constituents and

future contaminants of concern

• Relatively consistent performance

• Modular design with small footprint, easily

expanded

• Elimination of lime handling and lime

softening residuals


Disadvantages of Membrane Treatment

• Relatively high capital cost

• Requires consistent pretreatment to minimize

scaling/fouling

• Susceptible to damage by oxidants

• May require additional post-treatment

(degasification, pH adjustment, and/or

blending)

• Disposal of reject water (typically 20% of

feed water flow)


Current Methods of

Reject Waste Disposal in Ohio

• Dilution and discharge to receiving streams

– Direct

– Through wastewater treatment facility


Reject Waste Disposal Limitations

• Primary limiting factor is the TDS surface

water limits

– 1,500 mg/l outside mixing zone

– 3,000 mg/l toxicity limit at point of discharge


Alternative Disposal Method?

Deep Well Injection

– Discussion based on a current project regarding

feasibility of Class I (non-hazardous) Injection Well


Deep Well Injection

What is an injection well?

Well into which fluids are

being injected

What is an USDW?

– Underground source of

drinking water – goal is to protect!

What is a confining zone?

– Geological formation or group

of formations capable of limiting

fluid movement above an injection zone


Injection Well Classifications

• Class I – used to inject hazardous and non-hazardous

wastes into deep, isolated rock formations

• Class II – used to inject fluids associated with oil and

natural gas production

• Class III – used to inject fluid to dissolve and extract

minerals (solution mining)

• Class IV – classification no longer used; EPA banned

in 1984

• Class V – used to inject non-hazardous fluids

underground, into or above USDWs

• Class VI – used to inject CO 2 into subsurface rock

formations for storage (geologic sequestration)


Bedrock Geologic Map of Ohio


Geology – General Stratigraphic Section


Permitting

• Strict permitting is in place to ensure

protection of USDWs by isolation of injected

waste fluids

• Permits required for each Class I well by Ohio

EPA cover the following issues:

Well siting requirements

Well construction requirements

Injection operations and maintenance

requirements


Seismic Reflection Survey

• Seismic reflection surveys required to determine

presence or absence of geologic features that

may affect injection well operations such as

faults, fractures, stratigraphic changes, or

structural features.


Seismic Reflection Survey Results


Next Steps

• Area of Review (AOR) analysis

– Analysis of the surrounding area to identify

artificial penetrations (existing well, abandoned

wells, etc.) that might allow fluid to move out of

the injection zone.

• Complete geologic evaluation and suitability

– Includes geologic evaluation, seismic reflection

survey results, AOR analysis


Next Steps (cont.)

• Complete and submit Class I Permit to Drill

(non-hazardous)

– Provides details concerning well construction

• Install an Injection Well

– Includes testing


Is Deep Well Injection for Me?

• Only a possible solution – won’t apply to

every situation

• Viability closely tied to geologic suitability

• May be a suitable backup system in

some situations

• Financial considerations


Questions?

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