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
Overview of PresentationOverview of Presentation
••• 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
Overview of PresentationOverview of Presentation
••• BackgroundBackgroundBackground
••• Pollutants of Concern (POCS)Pollutants of Concern (POCS)Pollutants of Concern (POCS)
> 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
••• 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
Overview of PresentationOverview of Presentation
••• BackgroundBackgroundBackground
••• Pollutants of Concern (POCS)Pollutants of Concern (POCS)Pollutants of Concern (POCS)
••• Maximum Allowable Headworks Loading (MAHL)Maximum Allowable Headworks Loading (MAHL)Maximum Allowable Headworks Loading (MAHL)
> Available Industrial Loading (AIL)g ( )
••• Allocation StrategiesAllocation StrategiesAllocation Strategies
••• ImplementationImplementationImplementationImplementationImplementationImplementation
••• ResultsResultsResults
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)
Overview of PresentationOverview of Presentation
••• BackgroundBackgroundBackground
••• Pollutants of Concern (POCS)Pollutants of Concern (POCS)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 Strategies
••• ImplementationImplementationImplementationImplementationImplementationImplementation
••• ResultsResultsResults
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
Overview of PresentationOverview of Presentation
••• BackgroundBackgroundBackground
••• Pollutants of Concern (POCS)Pollutants of Concern (POCS)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
> Implementation> Implementation
••• ResultsResultsResults
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
Ni k l E lNickel Example
CFL Modified = AIL – Loading CIU – Loading Non‐Contributing Non‐CIUs
Flow 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
Ni k l E lNickel Example
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)
Ni k l E lNickel Example
CFL = AIL – Loading – LoadingCFL Modified = AIL – Loading CIU – Loading Non‐Contributing Non‐CIUs
Flow Contributing Non‐CIUs
/CFL Modified = ( 56.0 ‐ 20.5 ‐0.14 ) lb/d
( 0.32 mgd) (8.34)
= = 13 mg/L13 mg/L
Overview of PresentationOverview of Presentation
••• BackgroundBackgroundBackground
••• Pollutants of Concern (POCS)Pollutants of Concern (POCS)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
> Implementation> Implementation
••• ResultsResultsResults
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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