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Presented to: Southern California Alliance of POTWs

LOCAL LIMITS ‐METHODOLOGY, ISSUES, AND , ,ALTERNATIVES

September 25, 2012

Barbara Sharatz

Overview of PresentationOverview of Presentation

• Background

• Pollutants of Concern (POCS)

• Maximum Allowable Headworks Loading (MAHL)

• Available Industrial Loading (AIL)

• Allocation Strategiesg

• Implementation

• New Local Limits

Point Loma POTWPoint Loma POTW

• 301 (h) WAIVER

• 240 MGD CAPACITY / 165 MGD ACTUAL• 240 MGD CAPACITY / 165 MGD ACTUAL

• ADVANCED PRIMARY

4 5 MILES OFFSHORE 310 f DEEP• 4.5 MILES OFFSHORE, 310 ft DEEP

• 204 Dilution Factor

Team Building MeetingTeam Building Meeting

• TEAMMEMBERSTEAM MEMBERS• Consultants• EPA Region IX• Wastewater Dept Management• Laboratory Manager and Supervisors• Pretreatment ProgramManager and• Pretreatment Program Manager and

Supervisors• PERSONAL WORK STYLES• PROJECT GOALS• CHARTER / GROUND RULES• COMPLAINT RESOLUTION

Project Success Depends Upon Meeting Specific ObjectivesMeeting Specific Objectives

Protect the POTW Minimize Impact onpIndustrial Users

Be TechnicallyBased / DefensibleBased / Defensible Be Easy to

Administer


••• BackgroundBackgroundBackground

> Pollutants of Concern (POCS)

••• Maximum Allowable Headworks Loading (MAHL)Maximum Allowable Headworks Loading (MAHL)Maximum Allowable Headworks Loading (MAHL)

••• Available Industrial Loading (AIL)Available Industrial Loading (AIL)Available Industrial Loading (AIL)g ( )g ( )g ( )

••• Allocation StrategiesAllocation StrategiesAllocation Strategies

••• ImplementationImplementationImplementationImplementationImplementationImplementation

••• New Local LimitsNew Local LimitsNew Local Limits

Local Limits are POTW SPECIFICLocal Limits are POTW SPECIFIC

Meet NPDES permit limits

Meet quality requirements for effluent and l dsludge

Protect treatment plant processes

Ensure worker health and safety:

prevent fume toxicity and explosions

Potential Pollutants of Concern (POCs): PRIMARY(POCs): PRIMARY

• REGULATORYNPP A Cd C C CN Pb H Ni A Z M S• NPP: As, Cd, Cr, Cu, CN, Pb, Hg, Ni, Ag, Zn, Mo, Se,

BOD5, TSS, and ammonia (where the POTW

accepts ammonia from non‐domestic sources)

• Existing Local Limits: As, An, Be, Cd, Cr, Cu, Pb, Hg, Ni, Ag, Zn, CN, pH, G&O, Sulfides, Phenol, Pesticides and PCBs

Potential Pollutants of Concern (POCs): PRIMARY(POCs): PRIMARY

• ENVIRONMENTAL• Water Quality: NPDES Permit and Ocean PlanWater Quality: NPDES Permit and Ocean Plan

• Sludge Quality: 40 CFR 503 and California Title 22

• Inhibition: PRELIM 5• Inhibition: PRELIM 5

• Benchmarks: Goals in 301 (h) permit = 95% plant performance 1990 ‐ 1994performance, 1990 1994

‐ Expressed in metric tons/yr: Convert to [mg/L]‐ ~1/100 NPDES permit limits/ p

Screening to ID POCsScreening to ID POCs

MAXIMUM POTW INFLUENT AND EFFLUENT VALUES:

• Influent > Effluent Criteria?

• Effluent > 1/2 Effluent Criteria?

• Sludge > 1/2 Sludge Criteria?

• Influent > 1/4 Inhibition Criteria

RESULTS:

• 31 Pollutants of Concern31 Pollutants of Concern

• Controlling Criteria = Benchmarks

SECONDARY POCsSECONDARY POCs

• ND and;ND, and;

• Detection limit > screening criteria, and;

• Found in IU discharge samples or chemical

inventory lists

Pollutant SourcesPollutant Sources

SIU Industrial usersCommercial usersResidential / domestic users

Trucked Industrial and Domestic Waste

Upstream WRPs and WTPs discharging sludge p g g g

Metro Biosolids Center centrate return stream

Water Supply & Distribution Systempp y y

Inflow /Infiltration

Navy shipboard wastesNavy shipboard wastes

Data‐handling Issues:Background DataBackground Data

Goal: Characterize variability and reduce effect ofGoal: Characterize variability and reduce effect of outliers and non‐detects

• 1. Selection of statistical methods considers measure of variability

• 2. Conventions for outliers

• 3. Conventions for non‐detects

Select Representative Background ConcentrationsConcentrations

Example: ArsenicExample: Arsenic

• 75 samples• 49 below MDL• Concentration Range: < 45 ug/L to 2200 ug/L

B h k 3 0 /L46.9

2500

g/L)

• Benchmark = 3.0 ug/L

1000

15002000

trat

ion

(ug

0

5001000

S l N b

Conc

ent

Sample Number

Variability Strongly Affects Statistical MeasuresStatistical Measures

2nd Decile

Average

Median

0 100 200 300

Concentration (ug/L)

Example Arsenic: NDs are assumed as ½ MDLExample Arsenic: NDs are assumed as ½ MDLWhich value is representative of background?Which value is representative of background?

Example: MolybdenumExample: Molybdenum• 75 Samples

• 71 below MDL• 71 below MDL

• Concentration Range: <15 ug/L to 150 ug/L

C it i 2 7 /L• Criteria = 2.7 ug/L

200on

100

150

ncen

tratio

(ug/

L)

0

50Con

S l N bSample Number

NDs increase uncertainty, especially where DLs are higher than criteria

MDL

where DLs are higher than criteria

NDs = 0 5 DL

NDs = DL

MDL

NDs = 0

NDs = 0.5 DL

0 5 10 15 20Average Concentration (ug/L)

Example Molybdenum: which value is representative of Example Molybdenum: which value is representative of background?background?background? background?

For Background LoadingsFor Background Loadings

• Use Average ValuesUse Average Values

• For NDs:• If Zero Detects ND = 0If Zero Detects, ND 0• If > 1 Detect, ND = 0.5 MDL• If 1 Detect, Is value > 2X MDL?If 1 Detect, Is value 2X MDL?

• Yes = slug, ND = 0• No = value, ND = 0.5 MDL,

Source CharacterizationSource Characterization

Sampling Results Projectedp gfrom Sources

Projected Flow Rates

Controllable Controllable LoadingLoading

Uncontrollable Uncontrollable LoadingLoadingI / II / I

Ship’s Ship’s Waste Waste

SLUDGE SLUDGE CENTRATECENTRATE

Safety FactorSafety Factor

High Safety Factor => Expensive Pretreatment

Low Safety Factor => NPDES Fines and Process Upsets

Safety Factor Approach Strives to Minimize Number of UnknownsMinimize Number of Unknowns

Safety Allowance

Allowable Headworks LoadingAllowable Headworks Loading

Growth Safety AllowanceGrowth Safety Allowance

Allowable Headworks LoadingAllowable Headworks Loading

Safety Allowance

Influent LoadingLoading

TiTime

Safety Factor Approach Addresses Analytical Uncertainty for Special CasesAnalytical Uncertainty for Special Cases

Allowable Headworks LoadingSafety Allowance

InfluentInfluent Loading

Date Concentration1/2/96 <DL

Time

1/2/96 <DL1/4/96 0.0031/6/96 0.002

DetectionDetection Level 0.002

Concentrations at orConcentrations at or Near Detection Level

Safety Factor Predicts Capacity Needs for Future Growthfor Future Growth

Industrial IndustrialWastewater Flow

TimeTimeMature Service Area Growing Service Area

Experience Shows Safety Factor for Growth Varies from 0 - 5 %Experience Shows Safety Factor for Growth Varies from 0 5 %

Safety Factor Approach Develops Fair and Protective Safety Allowanceand Protective Safety Allowance

S f tSafety Allowance

Allowable Headworks Loading

3 Groups of POCs3 Groups of POCs

• High background, high influentHigh background, high influent

• Variable influent variable backgroundVariable influent, variable background

••• Low influent low backgroundLow influent low backgroundLow influent low background••• Low influent, low backgroundLow influent, low backgroundLow influent, low background



••• Pollutants of Concern (POCS)Pollutants of Concern (POCS)Pollutants of Concern (POCS)

> Maximum Allowable Headworks Loading (MAHL)




••• ResultsResultsResults

Maximum Headworks Loading CalculationsCalculations

PLANT REMOVAL EFFICIENCIES• PLANT REMOVAL EFFICIENCIES– Outliers: 99% confidence interval

IF NDs– IF NDs:

• Used Paired Data Sets • Literature Values• Literature Values

• USED PRELIM 5 0 FOR MAHL CALCS• USED PRELIM 5.0 FOR MAHL CALCS

Maximum Allowable Headworks Loading Protects Most Sensitive CriteriaLoading Protects Most Sensitive Criteria

Allowable Headworks Loading = Criteria x Projected Plant Flow(1- Removal Efficiency)

NICKEL

NPDES

CA Title 22-Sludge

U.S. 503 - Sludge

Anaerobic Inhibition Threshold

Benchmark MAHLMAHL100 150 00 3000

AHL (lb/d)50 100 150 500 3000





> Available Industrial Loading (AIL)g ( )




AIL Remains after Uncontrollable Loading and Safety Allowance are Removedand Safety Allowance are Removed

Domestic/Commercial

Nickel Example

Domestic/CommercialLoading 7.5 lb/d

Other UncontrollableLoading 4.8 lb/d

Available IndustrialLoading (AIL) 56 lb/d

Total Pie = 68.2 lb/d MAHL

(MAHL based on Benchmark)(MAHL based on Benchmark)






> Allocation Strategies



Conventional Allocation Strategies are Simple But Can be RestrictiveSimple But Can be Restrictive

Uniform Concentration Method

________AILAIL___ ___ UCLUCL FlFlUCL = UCL = Flow Flow IndustriesIndustries

UCL UCL = 1.4 mg/L= 1.4 mg/L

Conventional Allocation Strategies are Simple But Can be RestrictiveSimple But Can be Restrictive

Uniform Concentration Contributory Flow Method Method

All IndustriesAll Industries Contributing Contributing

AILAIL AIL – Loading Non-Contributing CFL = Flow

All IndustriesAll Industries IndustriesIndustries

UCL = UCL = Flow Flow IndustriesIndustries

UCL UCL = 1.4 mg/L= 1.4 mg/LCFL = Flow ContributersCFL = 5.2 mg/L

Characterization of SIUs Provides Opportunities for Modified AllocationOpportunities for Modified Allocation

8 02Nickel

5.2 mg/L--------------

8.02

2.82 mg/L

Nickel

2.38 2.38 mg/Lmg/LMonthlyMonthly

ConventionalConventionalCFLCFL

--------------g

UnusedUnused 5.2 mg/L

MonthlyMonthlyAverageAverage

CategoricalCategorical• Metal Finishers

NonNon--CategoricalCategorical• Industrial Laundries• Metal Finishers • Industrial Laundries•Trucked Industrial

Modified CFL Allocates Remaining Loading Among Contributing Non‐CIU IndustriesAmong Contributing, Non‐CIU Industries

• Sum Flow Rates Of Contributing Non‐ CIU IndustriesIndustries

• Calculate Modified CFL







> Implementation> Implementation


Ni k l E lNickel Example

CFL Modified = AIL – Loading CIU – Loading Non‐Contributing Non‐CIUs

Flow Contributing Non‐CIUs

CFL Modified = ( 56.0 ‐ ‐ ) lb/d

( mgd) (8.34)

Federal Discharge Limit Determines CIU LoadingsCIU Loadings

• Determine representative flow rate per sewerDetermine representative flow rate per sewer connection

• Assign Federal Discharge Limit for Pollutantg g

Nickel Example:Nickel Example:Nickel Example:Nickel Example:

Loading Loading CIUCIU = = (Flow) (Flow) CIU * CIU * (Limit)(Limit)FederalFederal

= 20 5 lb/d= 20 5 lb/d= 20.5 lb/d= 20.5 lb/d


CFL Modified = AIL – Loading CIU – Loading Non‐Contributing Non‐CIUs


CFL Modified = ( 56.0 ‐ 20.5 ‐ ) lb/d

( mgd) (8.34)

Average Domestic Concentration Determines b dNon‐Contributing, Non‐CIU Loading

• Sum Flows of Non‐Contributing Non‐CIUs

• Apply Average Domestic Concentration

Nickel Example:Nickel Example:pp

LoadingLoading = (Flow)= (Flow) X (Concentration)X (Concentration)Non‐Contributing Non‐Contributing DomesticNon Contributing Non Contributing Domestic

= 0.14 lb/d = 0.14 lb/d


CFL Modified = AIL – Loading CIU – Loading Non‐Contributing

Flow Contributing Non CIUsFlow Contributing Non‐CIUs

CFL Modified = ( 56.0 ‐ 20.5 ‐ 0.14 ) lb/d

( mgd) (8 34)( mgd) (8.34)


CFL = AIL – Loading – LoadingCFL Modified = AIL – Loading CIU – Loading Non‐Contributing Non‐CIUs


/CFL Modified = ( 56.0 ‐ 20.5 ‐0.14 ) lb/d

( 0.32 mgd) (8.34)

= = 13 mg/L13 mg/L







> Implementation> Implementation


Modified CFL Significantly Increased Allowable Concentration to Contributing Non CIUsConcentration to Contributing Non‐CIUs

NICKEL

1312

14m

g/L)

6

8

10

trat

ion

(m

1 4

5.2

2

4

6

Con

cen

1.40

UCL ConventionalCFL

San DiegoModified

CFL

Modified CFL Provided Greater Flexibility for All MetalsFlexibility for All Metals

70

80

Modified CFLC ti l

50

60

(mg/

L)

Conventional CFL

20

30

40

entr

atio

n (

0

10

20

Con

ce

0Cadmium Chromium Copper Lead Nickel Zinc

LOCAL LIMIT EVALUATION RESULTSLOCAL LIMIT EVALUATION RESULTS

llEliminateEliminate

•Antimony

•Arsenic•Thallium•Silver•Arsenic

•Beryllium•Silver•Phenols

•Mercury

•Selenium•Pesticides / PCBs

New LimitsNew Limits

•• ConventionConventionOLDConventionConvention

POLLUTANT

OLD LIMIT (mg/L)

NEW LIMIT

Screening Level

Control Criteria

Cadmium 1.2 3.8 0.009 BCadmium 1.2 3.8 0.009 BChromium 7 59 0.016 BCopper 4.5 11 0.16 BCyanide 1.9 1.9 1.9 BLead 0.6 73 0.036 BNickel 4.1 13 0.015 BZinc 4.2 24 0.3 BFlash Point >140 >140 >140 H&SOil & Grease 500 500 500 NPDESSulfides 1 1 1 H&SpH 5 0 11 0 5 0 12 5 TITLE 22pH 5.0 - 11.0 5.0 - 12.5 TITLE 22

San Diego Modified CFLs are Less Restrictive Easy to AdministerRestrictive, Easy to Administer

• Allows full federal discharge limit for CIUs

• Provides greater allocation to contributing, non‐CIUs

• Permits with Federal Limits unchangedPermits with Federal Limits unchanged

REFERENCESREFERENCES

• 1. City of San Diego Urban Area Pretreatment Program y g gFinal Report prepared by Malcolm Pirnie, Inc., 1996

• 2. WEF Presentation prepared by Malcolm Pirnie, Inc. d th Cit f S Di 1996and the City of San Diego, 1996

• 3. EPA Guidance Manual on the Development and Implementation of Local Discharge Limitations Under p gthe Pretreatment Program, December 2004

• 4. Residential and Commercial Toxic Pollutant Loadings d POTW R l Effi i E i i M 1991and POTW Removal Efficiency Estimation, May 1991

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