Ammonia Site-Specific CriteriaProjected WQB Effluent Limits

Alex Renew & Lynchburg

Laurissa Cubbage, PE

VWEA - Southwest Virginia Regional Activities Committee

March 23, 2017

1

Agenda

Background on EPA Ammonia WQBEL

Approach to predicting criteria

Alex Renew: Tidal receiving water, effluent dominated

City of Lynchburg: Large receiving water

2

Basis of Projected Criteria

Aquatic Life Ambient Water Quality Criteria for Ammonia –Freshwater – 2013▪ EPA recommendations to states

Regulates pollutant concentrations in surface waters (fresh, brackish, and/or salt waters)

Based solely on data and scientific judgments relative to the pollutant’s potential for effecting the environment and humans

Criteria is not a rule▪ Does not automatically become a state’s WQ standard

▪ States required to adopt criteria in developing their own WQ standards

3

Ambient Water Quality Criteria for

Ammonia in Freshwater

Ammonia as N [NH3] is toxic as opposed to NH4+

High levels of NH3 prevents aquatic life from secreting ammonia ▪ Builds up in internal tissues and blood

▪ Causes long-term reproductive problems and death

Criteria is developed using toxicity studies for most sensitive freshwater species known at the time▪ Rainbow Trout (salmonid fish)

▪ Early Life Stage Lepomis

▪ Mussels (unionid mussels)

Separate acute and chronic criteria are provided

4

Sensitive Species

Freshwater mussels (Unionidae family)▪ All states have at least one freshwater unionid mussel native or present in

some of their waters

▪ Single national acute and chronic criterion applied to all waters rather than different criteria based on the presence or absence of mussels

▪ Unionids representative of sensitive invertebrate genera and fish early life stages

▪ Unionids determine chronic criterion for all temperatures

▪ Unionids determine acute criterion at water temperatures above 15.7° C

Rainbow trout (Salmonidae family)▪ Rainbow trout known as commercially and recreationally important

▪ Representative of most sensitive fish in general

▪ Salmonids determine acute criterion at water temperatures below 15.7° C

5

Freshwater Ammonia CriteriaEPA Regulatory Timeline

1976: First developed criteria to protect aquatic life

1985: First update

1999: Second update based on fingernail clams as well as

▪ Salmonid fish (Acute)

▪ Bluegill sunfish in early life stage (Chronic)

2003: New toxicity studies found other freshwater aquatic species

that are more sensitive to ammonia (unionid mussels)

2009: Draft update was released for peer review based on

▪ Toxicity studies recommending the use of unionid mussels

▪ EPA verified the recommendations using gill-breathing snails

2013: Finalized update to ammonia criteria for application nation-

wide using both the above species6

Freshwater Ammonia CriteriaIn Virginia

Final amendments to WQS published Aug 2016 Virginia

Register▪ EPA Approval expected mid-2017

Ammonia criteria deferred from this Triannual Review

Follow-up RAP & Comment Period. Looking at Sept 2017 SWCB

meeting for adoption

VAMWA: All POTWs should take a look at their plants▪ “The new ammonia criteria are far more stringent because of the addition to the

underlying toxicity data base of freshwater mussel species and other organisms that are

particularly sensitive to ammonia. They are also more highly dependent than the current

criteria on temperature and pH. We have a concern that in future permit cycles, a closer

focus on warm weather diurnal pH cycles, affected by algae growth, could drive the pH-

dependent ammonia limits considerably lower.”

7

Acute Criteria▪ Criterion Maximum Concentration (CMC)

▪ 17 mg/l of Total Ammonia Nitrogen (TAN) @ pH 7 and 20°C

▪ 1-hr average duration

Chronic Criteria ▪ Criterion Chronic Concentration (CCC)

▪ 1.9 mg/l of Total Ammonia Nitrogen (TAN) @ pH 7 and 20°C

▪ 30-day average duration

Highest 4-day average should not exceed 2.5x the chronic criteria

Exceedance once in three years on average is permitted

Understanding the New Criteria

EPA’s 2013 Update

8

Understanding the New Criteria pH and Temperature Dependent

0

10

20

30

40

50

60

70

80

90

100

5 6 7 8 9 10 11 12 13

pH

%NH3 @ 40-degrees C %NH3 @ 30 degrees C

%NH3 @ 20 degrees C %NH3 @ 10-degrees C

Percent of

Ammonia in

Toxic NH3 form

40°C

30°C

10°C

9

Criteria for Allowable Dilution Levels▪ Based on upstream 7-day 10-year drought flows (7Q10)

▪ Can only use 25% of the 7Q10 flows for dilution

▪ For Acute Criteria

▪ Tidal flows introduce more complex mixing scenarios

Hunting Creek is Effluent Dominated▪ Stream flow based on 7Q10 = 1.9 cfs (from VPDES Permit Fact Sheet)

▪ 7Q10 flow allowable for dilution = 0.5 cfs

▪ WRRF Effluent (permit) = 84 cfs (54 MGD)

Understanding the New Criteria Considerations for Dilution

10

Ammonia Criteria & Permit LimitsProcess for Estimating

11

Permit Limits•Monthly

•Weekly

Permit

Guidelines

(TSD)•DEQ STAT

Program

EPA Criteria•CMC

•CCC

Receiving

Stream Data•pH, temp, NH3 from

DEQ database

•Q from USGS

Plant Effluent

Data•Q, pH, temp, NH3

Mixing

Scenario•DEQ MIX

Program

•Plant Q

•Stream Q

•Stream Dim’s

Criteria

Calculations

Estimating permit limits▪ Run DEQ’s “mixer” program

▪ Determine if mixing allowed to full extent

▪ Applies to Lynchburg case, where receiving water dominates

▪ Run STATS program for WLA▪ Convert Chronic & Acute criteria to permit limits

▪ Consider alternative estimating techniques if new limits a challenge▪ Alternative pH and temperature pairing

▪ Collect new receiving stream data

▪ Attempt to disprove presence of sensitive species

▪ Consider alternative permit limit tradeoffs▪ i.e. lower pH limit to allow higher NH3 limit

Discussion with DEQ needed to confirm:▪ Will permit conditions change to meet principles of EPA guidance?

▪ Allowance of one exceedance every three years on average?

▪ Implementation timeline (coincide with next permit renewal?)

▪ Confirm assumptions regarding mixing

12

What do we do next?

AlexRenew

13

Alex Renew WRRFOutfall and Receiving Waters

14

Plant

Outfall

(50 cfs)

WRRF

Hunting Creek

Embayment

Potomac River

N

DEQ

Monitoring

Location

Ammonia Criteria & Permit LimitsProcess for Estimating

15

Permit Limits•Monthly

•Weekly

Permit

Guidelines

(TSD)•DEQ STAT

Program

EPA Criteria•CMC

•CCC

Receiving

Stream Data•pH, temp, NH3 from

DEQ database

•Q from USGS

Plant Effluent

Data•Q, pH, temp, NH3

Mixing

Scenario•DEQ MIX

Program

•Plant Q

•Stream Q

•Stream Dim’s

Criteria

Calculations

Projected Effluent Limits

VPDES Permit Limit, Ammonia as N (mg/L)

SeasonMonthly Weekly Daily

Current Projected % Δ Current Projected % Δ Current Projected

Current PermitFebruary – March

April – OctoberNovember – January

6.91.08.4

2.40.81.8

65%20%79%

8.54.4

10.0

2.81.02.2

67%77%78%

NANANA

4.81.63.6

Alternative Seasons (i.e. Richmond)June – October

November – May

1.06.9 – 8.4

0.81.6

20%77% ±

4.48.5 – 10.0

1.01.9

77%77%±

NANA

1.63.2

NOTES:1. New monthly basis is “rolling 30-day average,” but could be enforced as calendar month average.2. New weekly basis is “highest 4-day average within the 30 days.”3. New daily basis is “one-hour average.”4. Limits “not to be exceeded more then once in three years on average.”5. Assumes presence of sensitive species (freshwater mussels and rainbow trout).6. Assumes effluent-dominated receiving water (no mixing).

16

NEW LIMIT

CATEGORY

ALTERNATIVE DEFINITION

OF SEASONS COULD BE

MORE RESTRICTIVE

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Pla

nt

Eff

luen

t N

H3

(mg

/l)Projected Chronic (Monthly) Effluent Criteria

vs. Historical Effluent Ammonia

17

New

Monthly

Limit

Calendar month average

of daily readings

February 2003 BRB Startup

Monthly average exceeded

limit

2003-2015 EXCEEDANCES: 1

BRB 6

Startup

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Pla

nt

Eff

luen

t N

H3

(mg

/l)

18

New

4-day

Limit

Projected 4-day (Weekly) Effluent Criteria vs. Historical Effluent Ammonia

Rolling 4-day average

of daily readings

February 2003 BRB Startup

Highest 4-day average

exceeded limit

August 2003 BRB Startup

Highest 4-day everage

exceeded limit

2003-2015 EXCEEDANCES: 2

BRB 6

Startup

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Pla

nt

Eff

luen

t N

H3

(mg

/l)

19

Projected Acute (Daily) Effluent Criteriavs. Historical Effluent Ammonia

New Daily Limit

(1-hr average)

Recorded Effluent Ammonia

(One reading per 24-hrs)

February 2003 BRB

Startup

August 2003 BRB Startup

Exceeded summer limit on

2 days

2003-2015 EXCEEDANCES: 2

BRB 6

Startup

City of Lynchburg

20

Lynchburg WRRFOutfall and Receiving Waters

21

Plant

Outfall

(65 cfs)

N

James

River

(303 cfs)

Ammonia Criteria & Permit LimitsProcess for Estimating

22

Permit Limits•Monthly

•Weekly

Permit

Guidelines

(TSD)•DEQ STAT

Program

EPA Criteria•CMC

•CCC

Receiving

Stream Data•pH, temp, NH3 from

DEQ database

•Q from USGS

Plant Effluent

Data•Q, pH, temp, NH3

Mixing

Scenario•DEQ MIX

Program

•Plant Q

•Stream Q

•Stream Dim’s

Criteria

Calculations

City of LynchburgCurrent VPDES Limits vs. Est. Criteria

Ammonia as N (mg/L)

SeasonMonthly Weekly Daily

Current Projected % Δ Current Projected % Δ Current Projected

Current PermitApril – October

November – JanuaryFebruary – March

NANANA

0.9(1.9)2.4(5.4)3.0(6.7)

---

NANANA

2.3(4.7)6.0(13.5)7.5(16.7)

---

NANANA

5.2(16.8)13.3(43.5)15.3(50.3)

NOTES:1. New monthly basis is “rolling 30-day average,” but could be enforced as calendar month average.2. New weekly basis is “highest 4-day average within the 30 days.”3. New daily basis is “one-hour average.”4. Limits “not to be exceeded more then once in three years on average.”5. Assumes presence of sensitive species (freshwater mussels and rainbow trout).6. Assumes effluent-dominated receiving water (no mixing).

23

NOT A

PERMIT

CATEGORYNO MIXING

(MIXING)

Ammonia permit limits reduced by 50% minimum▪ Possibly as much as 75%

In-stream background pH and temperature▪ More of a concern than in the past

Estimate new criteria and permit limits now

▪ Anticipate and plan for impacts

24

Summary

Questions?

Laurissa Cubbage

919-270-2589

lcubbage@greeley-hansen.com