chloride and ammonia water quality standards update

Chloride and AmmoniaWater Quality Standards Update

AMI Environmental ConferenceKansas City, MissouriMarch 10, 2011

Gregory L. Sindt, P.E.515‐233‐6100gregsi@bolton‐menk.com

Application of Standards

Standards apply to concentrations in the streamLow stream flows used as basis– 7Q10 or lowest flow in seven consecutive days in ten years (0.2% probability)

Treatment plant maximum design flow typically used as basisVery conservative approach

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Acute Ch

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Sulfate, mg/L

Acute Chloride Standard300 mg/L Hardness

1988 Guideline

EPA Jan 2009

EPA w/ Data Added

Standards Development

STATES develop water quality standards as administrative rules– Technical advisory committee approach in some states

– Public comment on draft rules

US EPA Regional Offices review and approve state standards


EPA develops National Guideline Criteria for many toxics (304(a) Criteria Document)– Peer reviewed– Public comment– GUIDELINES for reference by states

States are NOT required to adopt the National Criteria as state standards


STATES develop standards that are adequate for protection of water uses in the state– Adopt or modify EPA Guideline Criteria

Less stringent than EPA National Criteria if sensitive species included in EPA Criteria are not present in StateMore stringent than EPA National Criteria if sensitive species of significant economic or recreational benefit are present in State


States must review standards every three years– Revise standards to incorporate new toxicity data and EPA criteria

– Formal rule making process for standards revisions


Dischargers can develop “site specific” standards for its receiving stream– Develop less stringent standard by deleting data for sensitive species that would not be present in stream (species deletion procedure)

Ammonia Standards

December 2009 Draft EPA Update Document– Modification of 304(a) National Ammonia Criteria– Includes new data on freshwater mussels

Mussels extremely sensitive to ammonia

– Proposed two sets of criteriaMussels present criteriaMussels absent criteria

Ammonia Standards

Mussel present criteria very stringent– Mussels present chronic criteria only 15% of mussels absent criteria (pH 8, 25 deg. C)

– Mussel present criteria seven times more stringent than mussels absent criteria

Example at pH 8 and 25 degrees C1.8 mg/L chronic criteria mussels absent0.26 mg/L chronic criteria mussels present

– Five times more stringent than current criteria

Ammonia Standards

Public comments received in March 2011– Challenged mussel toxicity test methods for mussels

– Questioned lack of clear dose/response relationship

Ammonia Standards

EPA proposed revisions to draft document– New toxicity data on sensitive snails

Similar ammonia sensitivity as musselsSnails can live almost anywhere

– May replace the “mussels present” and “mussels absent” criteria with only one set of criteria

Criteria could be similar to draft “mussels present” for ALL STREAMS.

– Criteria will be five times more stringent than current

Ammonia Standards

Example comparison (ph 8, 25 degrees C)– 1.8 mg/L current chronic criteria– 0.26 mg/L proposed criteria

EPA schedule– February 2011 snail toxicity study peer review– Spring 2011 publish final criteria document

(Probably) single sets of acute and chronic criteria similar to “mussels present” draft criteria

Ammonia Standards

Impact of new criteria– Ammonia discharge limits on low flow streams could be very stringent (less than 0.5 mg/L)

– Consideration of mussels in criteria development will carry over to criteria for other water quality parameters

Concerns about mussel toxicity testing methods

Chloride Regulatory History

Inconsistent regulation of salts– Monitoring parameters

Total Dissolved Solids (TDS)Conductivity or increase in conductivitySpecific constituents

• Chloride• Sulfate• Expanding list

–Often ignored state standards

Chloride Standards Development

1988 EPA National Guideline Criteria– 860 mg/L acute– 230 mg/L chronic

States adopt standards– Specific standards for each state– Many states adopted the EPA guidelines

Chloride Standards Development2009 Iowa Adopts New Chloride Standards– Replaces TDS standard with chloride and sulfate– Chronic chloride standard significantly less stringent than EPA 304(a) National Guideline

– Standards less stringent for higher hardness– Standards slightly more stringent for higher sulfate– Default values (200 mg/L hardness, 63 mg/L SO4

2‐)389 mg/L chronic (230 mg/L EPA National Criteria)629 mg/L acute (860 mg/L EPA National Criteria)


May 2010 ‐ US EPA approved Iowa standards Chloride and sulfate standards approvedTDS deletion not yet approvedFish and Wildlife Service (FWS) may object to deleting TDS standard


2011 EPA plans to revise the National Criteria– Include the Iowa data in recalculating criteria– Anticipate national criteria will be similar to Iowa– Plan to publish draft criteria Spring 2011

Issues Regarding Iowa Standards

EPA has not approved deleting TDS standard– Fish and Wildlife Service may object

Antidegradation arguments– Revising the standards may be viewed as an increase in the discharge of pollutants

Issues Regarding Iowa Standards

Antibacksliding argument– New standards may be viewed as a relaxation of environmental standards

Protection of fingernail clam– Fingernail clam is most sensitive species in data base

– Some may consider standard not protective of fingernail clam

Emerging Choride/TDS Issues

EPA Benchmark for conductivity in Appalachian Streams – August 2010– Appalachia mining area concerns– Very stringent

300 uS/cm (equivalent to about 200 mg/L TDS)

Emerging Chloride/TDS Issues

Impact on fresh water mussels– Canadian draft chloride standards

Impact on glochidia life stage mussels128 mg/L chronic “benchmark”536 mg/L acute “benchmark”Included mussel glochidia data (EPA did not)

– Widespread interest in decline of mussel population in U.S.

– Carryover of mussel toxicity concepts from the EPA ammonia criteria revisions

Other StatesStates considering Iowa Standards– Kansas– Missouri– Kentucky– Indiana

Pennsylvania 2010 revisions– 500 mg/L TDS monthly mean standard END OF PIPE for new and increased discharges

– Chloride standards may be reviewed soon

Other StatesUS EPA advising other states to consider Iowa standardsAMI and other groups could encourage other states to adopt Iowa standards

Other States

States must conduct triennial review of water quality standards– Identify new pollutants of concern– Revised existing standards based on new information

Possible resistance to revising standards– Antibacksliding

Other States

Replace TDS or conductivity standards with specific parameters ‐ chloride and sulfate

Iowa Chloride Standards

Standards Details and Implementation Information


Chloride standards as function of hardness and sulfate concentrations–Acute: (287.8) (hardness)0.205797 (sulfate)‐0.07452

–Chronic: (177.87) (hardness)0.205797 (sulfate)‐0.07452


Default values if no site specific data– 200 mg/L Hardness (10th percentile)– 63 mg/L Sulfate

– 389 mg/L chronic Chloride standard– 629 mg/L acute Chloride standard

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Acute Ch

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Acute Chloride Standard65 mg/L Sulfate

1988 Guideline

Iowa Standard

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EPA Jan 2009

EPA w/ Data Added

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Acute Ch

lorid

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Iowa Standard

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Acute Ch

lorid

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EPA Jan 2009

EPA w/ Data Added

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Chronic Ch

lorid

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dard, m

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Hardness, mg/L as CaCO3

Chronic Chloride Standard65 mg/L Sulfate

1988 Guideline

Iowa Standard

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Acute Ch

lorid

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1988 Guideline

EPA Jan 2009

EPA w/ Data Added

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Chronic Chloride Stan

dard, m

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Sulfate, mg/L

Chronic Chloride Standard300 mg/L Hardness

1988 Guideline

Iowa Standard

IDNR Compliance Approach 1

Gather data for site specific standards derivation– Stream background chloride, hardness, sulfate– Discharge effluent hardness and sulfate– 100 data points required

Once per week for two yearsTwice per week for one year


Source Reduction Efforts (Voluntary)– Optimize home water softeners– Remove home water softeners– Replace home softeners with exchange tanks– Soften water only on selected use points– Remove/replace central ion exchange softeners– BMPs in industries to prevent salt discharge


Mandatory Source ReductionEvaluate options for chloride removal at wastewater treatment plantsCompliance Schedules in NPDES permits– Extended schedules in lieu of variances

Variances from Water Quality Standards– Affordability– Wide spread social and economic impact

Compliance Alternatives

No economical method for chloride removalSource reductionFlow augmentation (allowed for meeting discharge limits that are based on water quality standards)Effluent diffuser (eliminates mixing zone limitations)


Variances from standards– No economic alternatives– Temporary (must be working toward compliance with the standards)


Site specific standards– Evaluation of receiving stream– Delete species not expected to be in the stream from the calculation of standards

– Permanent modification (as compared with variance approach)

Questions and Discussion

Gregory L. Sindt, P.E.Bolton & Menk, Inc.gregsi@bolton‐menk.com515‐233‐6100

chloride and ammonia water quality standards update

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