SLIDE 1
CMA Position - Al
Current standard based on EPA document
well over 20 yrs old
New science and analyses are available:
Colorado Mining Association Standard Framework Meeting ALUMINUM - - PowerPoint PPT Presentation
Colorado Mining Association Standard Framework Meeting ALUMINUM - - PowerPoint PPT Presentation
Colorado Mining Association Standard Framework Meeting ALUMINUM AND IRON CMA Position - Al Current standard based on EPA document well over 20 yrs old New science and analyses are available: hardness based standards State and Federal
SLIDE 2
SLIDE 3
State and Federal Criteria - Al
National Recommended Water Quality Criteria
Non-Priority Pollutant:
Acute (pH 6.5 – 9.0) – 750 µg/L (total recoverable) Chronic – 87 µg/L (total recoverable)
Water-Effect Ratio may be appropriate.
Colorado Regulation 5 CCR 1002-31
Table III Metal Parameters:
Acute – 750 µg/L (total recoverable) Chronic – 87 µg/L (total recoverable)
Where pH ≥ 7, hardness ≥ 50 ppm in receiving water after
mixing, Al will be regulated based on acute criterion.
SLIDE 4
CGS Open-File Report 00-16 Naturally Degraded Surface Waters in CO
Chronic Guideline Acute Guideline
- Total recoverable Al consistently above Chronic Guideline
- Several high total recoverable Al have low Dissolved Al
SLIDE 5
State and Federal Criteria - Al
Arid West Water Quality Research Project
Evaluation of EPA Recalculation Procedure:
Included review of five EPA water quality criteria
including Aluminum
Al criteria updates includes hardness-
based relationship, similar to other metals
Provides stronger standard for
measurement of potential aluminum toxicity
SLIDE 6
Updated Aluminum Acute and Chronic Values
AWWQRP (2006) with further review in June
2009
New acute and chronic data reported Development of hardness-based equations More relevant to Al toxicity than current, single-
value, std
Mean Hardness (mg/L as CaCO3) Aluminum Equations 25 50 75 100 150 200 250 Updated Criteria Total Aluminum (μg/L) Acute= e(1.3695 [ln
(hardness)]+1.8308)
512 1,324 2,307 3,42 1 5,961 8,839 11,999 Chronic= e(1.3695 [ln
(hardness)]+0.9161)
205 530 924 1,37 2,388 3,541 4,807
SLIDE 7
CMA Position - Fe
Chronic Aquatic Life Iron Standard 1.0 mg/L
total recoverable iron.
Level difficult at times to meet during normal
flows.
Level much more difficult during times of
measurable suspended sediment.
Total recoverable does not accurately reflect
amount available to aquatic life, so dissolved should be used.
SLIDE 8
State and Federal Criteria - Fe
National Recommended Water Quality Criteria
Non-Priority Pollutant:
Acute – None Chronic – 1,000 µg/L (total recoverable) Colorado Regulation 5 CCR 1002-31
Table III Metal Parameters:
Acute – None Chronic – 1,000 µg/L (total recoverable)
SLIDE 9
CGS Open-File Report 00-16 Naturally Degraded Surface Waters in CO
Chronic Guideline
- Total recoverable Fe consistently above Chronic Guideline
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Iron –Water Quality Standard Other States
Illinois - General Use Water Quality Standard
– Dissolved Fe = 1.0 mg/L
Wyoming – Aquatic Life Chronic Value
- Dissolved Fe = 1.0 mg/L
Consideration to be given to dissolved rather
than total recoverable
SLIDE 11
Iron – Other Issues
Current criterion based primarily on field
- bservation – lack of guidance for deriving values
based primarily on field observations
Studies for acute/chronic toxicity insufficient to
derive iron criterion
A single criterion based on standard EPA
Guideline derivation will not adequately describe bioavailability, toxicity and ecological effects of iron on aquatic organisms due to solubility characteristics of ferrous (soluble) and ferric (generally insoluble) iron.
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Colorado Mining Association Water Quality Issues
Standards Framework Work Group Presentation August 19, 2009
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Low Flow: Issues
Definition of drought conditions Incorporation of drought conditions into low flow / critical flow calculations Flow monitoring and estimation techniques Critical flow application during high receiving water flows (i.e., wet weather conditions)
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Low Flow: Recommendations
Consider removal of drought years, or use of other protocols and data collection to assist in low flow / critical flow determination when a period of record is less than 10 years Recommend using 30E2 (chronic) and 1E2 (acute) rather than 30E3 and 1E3 for setting water quality based effluent limits Allow permittee to request use of monthly low flow values for all permit constituents Allow alternate dilution flow allowances for non-continuous discharges that occur in response to storm events (“real- time” permitting)
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Reasonable Potential: Issues
Statistical projection of the maximum projected effluent concentration Accommodation of statistical outliers Handling small effluent databases
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