Local Limits Crash Course Gorman Lau, P.E. CWEA 2016 P3S Conference - - PowerPoint PPT Presentation

Local Limits Crash Course

Gorman Lau, P.E. CWEA 2016 P3S Conference February 29, 2016

Presentation Outline

 Background  Local limit evaluations  Local limits update/development  Local limits implementation  Local limits troubleshooting  Summary and Q/A

2

Why have a Pretreatment Program?

 Protect POTW from interference or upset of

treatment operations

 Prevent pass-through of pollutants  Prevent harm to POTW infrastructure  Protect biosolids quality  Protect public health and safety

3

Who must have a Pretreatment Program?

 Defined in 40 CFR

Part 403

 POTWs with design

flow > 5 mgd

 POTWs with design

flow ≤ 5 mgd

 Directed by

regulatory agency

4

What is required for Pretreatment Program?

 Pretreatment Program Documents

 Administrative procedures  Sewer Use Ordinance (SUO)/Legal Authority

 General and specific prohibitions  Categorical limits  Local limits

 Enforcement Response Plan (ERP)  Wastewater discharge permits/control mechanism

 Program approved by Regional Water Board

5

What are general and specific prohibitions?

 Narrative discharge limits

 General prohibitions – no discharge of pollutants

causing pass-through or interference

 Specific prohibitions – characteristics of wastewater

that cannot be discharged into collection system (e.g., pH, temperature, fire/explosive hazards)

 Required by 40 CFR Part 403.5  Example language in USEPA Model Sewer Use

Ordinance

6

What is a categorical limit?

 Effluent limits for industrial processes

 Regulates specific discharges from 35 industries  Concentration- or mass-based  Applied at end-of-process typically at end of

pretreatment system

 Required by 40 CFR Parts 405-471

7

What is a local limit?

 Technically-based effluent limit for industrial (or

• ther regulated) users

 Concentration- or mass-based  Applied at end-of-pipe

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Pollutant Pie

Background (non- regulated) Regulated Growth Hauled Waste Safety Factor

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Categorical vs. local limits

Discharge to collection system

Regulated process wastewater Non- regulated process wastewater

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Categorical lim its Local lim its

Categorical vs. local limits

Discharge to collection system

Regulated process wastewater #1 Regulated process wastewater #2 Non- regulated process wastewater

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Categorical lim its Local lim its

Categorical vs. local limits

Discharge to collection system

Regulated process wastewater

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Categorical & Local lim its

What is a local limit?

 Technically-based effluent limit for industrial (or

• ther regulated) users

 Concentration- or mass-based  Applied at end-of-pipe

 Required by 40 CFR Part 403.5  Guidance documents

 Local Limits Development Guidance (July 2004)  Local Limits Guidance (December 1987)

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Why do you need local limits?

 Protect POTW

 Infrastructure  Treatment process integrity  Final effluent quality (meet

discharge requirements)

 Biosolids quality

 Protect human health and

safety

 Protect the environment

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Applicability of restrictions

Restriction Categorical Industrial User Significant Industrial User Other Industrial Users General and specific prohibitions X X X Categorical limits X Local limits X X *

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* Local limits may apply

Life cycle of local limits

Update/Develop Local Limits Implement Local Limits Evaluate Local Limits

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Update/Develop Local Limits Implement Local Limits Evaluate Local Limits

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Why conduct a local limits evaluation?

 It may be required:

 Pretreatment compliance inspection (PCI)  Pretreatment compliance audit (PCA)  Discharge permit

 Things change over time  Local Limits Guidance recommends periodic

evaluations

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What things change?

 Treatment plant upgrades  Treatment process modifications  Wastewater/biosolids quality  Wastewater discharge effluent limits  Biosolids handling/disposal  Regulated user base  Water supply

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What do you want to get out of a local limits evaluation?

 Verify existing pollutants of concern  Identify new pollutants of concern  Assess existing data quantity and quality  Gain an understanding of the pollutant loadings

to the treatment plant

 Magnitude  Temporal variations/trends

 Determine next steps, if necessary

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How do you conduct a local limits evaluation?

 Identify pollutants of concern (POCs)  Compare recent influent pollutant loads with the

Maximum Allowable Headworks Loading (MAHL) for each pollutant

 Conduct compliance analysis  Document the evaluation

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Where do you find POCs?

 Existing local limits  2004 Local Limits Guidance

 15 national POCs  Appendix C: Pollutants Regulated by Categorical

Standards

 Appendix G: Literature Inhibition Values

 Discharge permits  Biosolids limits  Treatment design capacities

22

How do you compare influent loads to MAHLs?

 Local Limits Guidance thresholds

 Average influent load > 60 percent of MAHL  Maximum influent load > 80 percent of MAHL  Monthly average influent load > 80 percent of design

capacity for BOD, TSS, or ammonia

 Other thresholds  If any threshold exceeded, re-evaluate local limit  If threshold not exceeded, is a local limit

necessary?

23

What is a compliance analysis?

 Is treatment plant meeting

discharge limitations?

 Is treatment plant meeting

biosolids disposal limits?

 Have there been treatment plant

upsets?

 Are regulated dischargers

complying with local limits? Do they need more flexibility?

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What are the potential outcomes

• f a local limits evaluation?

 Confirm existing local limits are adequate

 Propose removal an unnecessary existing local limit

 Focus next steps/future effort

 Identify data gaps and additional sampling that may

be needed to complete the evaluation or update/develop local limits

 Consider implementing ongoing monitoring program

 Document results of evaluation

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Minimum Recommended Sampling Frequency (Ongoing)

Parameter Location < 5 MGD 5-10 MGD 10-50 MGD >50 MGD Pollutants with local limit Influent, Effluent, Biosolids Quarterly Quarterly Quarterly Every

• ther

month Pollutants with MAHLs, but no local limit Influent, Effluent, Biosolids Annually Semi- annually Semi- annually Quarterly Organic priority pollutants Influent Annually Annually Annually Semi- annually TCLP pollutants Biosolids Annually Annually Annually Annually Biosolids % solids and specific gravity Biosolids Semi- annually Once every 4 months Quarterly Every

• ther

month Source: 2004 Local Limits Guidance

Update/Develop Local Limits Implement Local Limits Evaluate Local Limits

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How do you update/develop local limits?

 Identify applicable operational/environmental

restrictions

 Review and collect relevant data  Conduct screening  Conduct headworks loading analysis

 Calculate removal efficiencies  Calculate MAHLs

 Calculate maximum allowable industrial loadings

(MAILs)  local limits

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What operational/environmental restrictions to consider?

 Treatment plant design capacities  Treatment process inhibition

levels

 Activated sludge  Nitrification  Trickling filters  Anaerobic digestion

 Effluent limits  Biosolids limits  Air quality standards

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What is the secret to local limits update/development?

HIGH QUALITY SITE-SPECIFIC DATA!!!

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POTW EFF NPDES NPDES

R Q C AHL × × = 34 . 8

PE PE AS AS

R Q C AHL × × = 34 . 8

POTW sldg sldg sldg sldg

R G Q PS C AHL × × × × = 34 . 8

Is it really that important?

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Pollutant USEPA (2004) Plant A (2012) Plant B (2013) Plant C (2014) Plant D (2015) Arsenic 11-78% 41% 7% 35% 47% Cadmium 25-99% 90% 78% 92% 94% Chromium 25-97% 86% 74% 89% 84% Copper 2-99% 85% 54% 91% 92% Lead 1-92% 95% 76% 95% 95% Mercury 1-95% 99% 74% 97% 99% Nickel 2-99% 19% 14% 61% 53% Silver 17-95% 95% 62% 96% 98% Zinc 23-99% 88% 31% 82% 95% Cyanide 3-99%

• 14%
• 170%
• 640%

58% Activated sludge treatment plant average removal efficiencies

Non- regulated dischargers Regulated dischargers Headworks Primary Treatment Secondary Treatment Tertiary Treatment Disinfection Effluent Biosolids Processing Disposal X X X X X X X X = Data locations

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X

Why do you need a Sampling and Analysis Plan (SAP)?

 Goal: Produce high quality scientifically-

defensible data that adequately characterizes the site-specific conditions

 Uncontrollable loads  Treatment plant removal efficiencies  Biosolids quality

 Outline all information related to sampling and

analysis activities

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What goes into a SAP?

 Sampling locations  Pollutants of concern  Sampling frequency  Types of samples  Analytical requirements  Quality assurance/quality control (QA/QC)

procedures

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Where to potentially sample?

 Collection system  POTW influent  Between treatment processes  Final effluent  Anaerobic digester  Biosolids to disposal

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Non- regulated dischargers Regulated dischargers Headworks Primary Treatment Secondary Treatment Tertiary Treatment Disinfection Effluent Biosolids Processing Disposal

?

X X X X X X X X = Potential sampling locations

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How do you select a collection system sampling site?

 Presence of regulated dischargers

 Types of commercial businesses present  Will commercial businesses be regulated?

 Size of the service area  Variability of flows, pollutant concentrations and

loadings

 Multiple drinking water sources  Presence of inflow/infiltration  Separate or combined sewer system

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Conduct Site Visit

 Identify sampling locations  Gain appropriate access/

permission

 Identify potential safety

hazards

 Determine equipment needs

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What do you sample for?

 15 National POCs

 11 metals (As, Cd, Cr, Cu, Pb, Hg, Mo, Ni, Se, Ag,

Zn)

 Cyanide  BOD, TSS, ammonia

 Other POCs identified in local limits evaluation

 Effluent/biosolids limits  Treatment process inhibition

 Tailor POC sampling/analysis efforts to sampling

location-specific needs

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Minimum Recommended Sampling Frequency (Initial)

Parameter POTW Influent POTW Effluent POTW Biosolids Collection System Organic Priority Pollutants 1-2 1-2 1 1-2 National POCs 7-14 7-14 2 7 POTW-specific POCs 7-14 7-14 2 7 Percent solids (biosolids) – – 2 – TCLP pollutants – – 1 – Source: 2004 Local Limits Guidance

Minimum Recommended Sampling Frequency (Ongoing)

Parameter Location < 5 MGD 5-10 MGD 10-50 MGD >50 MGD Pollutants with local limit Influent, Effluent, Biosolids Quarterly Quarterly Quarterly Every

• ther

month Pollutants with MAHLs, but no local limit Influent, Effluent, Biosolids Annually Semi- annually Semi- annually Quarterly Organic priority pollutants Influent Annually Annually Annually Semi- annually TCLP pollutants Biosolids Annually Annually Annually Annually Biosolids % solids and specific gravity Biosolids Semi- annually Once every 4 months Quarterly Every

• ther

month Source: 2004 Local Limits Guidance

When do you sample and how much is needed?

 Key considerations for when

 Collect samples during typical operational periods  Do not sample during/after precipitation events when

inflow/infiltration flows are high

 Avoid holidays, but capture weekend days as well

 Key considerations on how much

 Depends on local limits evaluation and identification

• f data gaps

 Availability of high-quality historic data  Ideally supplement historic data

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How are samples collected?

 Composite samples

 Flow-weighted (preferred)  Time

 Grab samples  Consider hydraulic

residence time

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What analytical information to include in SAP?

 Sample bottle requirements

 Bottle size and material  Preservatives  Ice/refrigerate samples to <6°C

 Hold times  Analytical methods

 40 CFR Part 136

 Detection limits

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How important are detection limits?

 Excessive non-detect

data can be difficult to use when calculating local limits

 Recommend lowest

detection limits possible

 DNQ data provides

more information than non-detect

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Reporting Limit (RL) Method Detection Limit (MDL) Detected Detected but not quantifiable ( DNQ) Non-detect

What QA/QC should be implemented?

 Clean sampling  Field controls  Laboratory controls  Sample chain-of-custody  Field logs

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What needs to be on sample chain-of-custody form?

 Contact information  Date and time  Double-check sample bottle counts and types  Identify analytical methods

 Request low detection limits at MDLs  Request DNQ data

 Request QA/QC analyses  Comments  Signatures

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What do you do with all these new data?

 Check QA/QC data for precision, accuracy,

adequacy, and hold times

 Look for aberrant data (outliers)

 Check measurement units  Request re-analysis  Conduct re-sampling

 Conduct mass balance

checks

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100 150 200 250 300 350 .01 .1 1 5 10 20 30 50 70 80 90 95 99 99.9 99.99 Concentration Probability

How to handle non-detect data?

 Non-detect data must be carefully assessed

 How much of data set is non-detect?  Were detection limits appropriate?

 Use a surrogate value

 Detection limit  One-half detection limit  Zero

 Use statistical methods (e.g., regression on

• rder [ROS])

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Do you need a headworks loading analysis?

 Criterion 1: Max [Ceff] > ½ water quality

criterion/standard, or Max [Cbiosolids] > ½ applicable biosolids criterion; or

 Criterion 2: Max grab [Cinf] > ½ inhibition level; or  Criterion 3: Max composite [Cinf] > ¼ inhibition

level; or

 Criterion 4: Max [Cinf] > 1/500th of applicable

biosolids criterion

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Source: 1987 Local Limits Guidance

What are the potential outcomes

• f the screening step?

 No criteria met  analysis complete,

headworks loading analysis not needed

 Consider headworks loading analysis

for national POCs at a minimum

 At least one criterion met  conduct

headworks loading analysis

 Insufficient data  may need to

conduct additional sampling to evaluate

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What is a headworks loading analysis?

 Analysis to determine the need for local limits for

each POC evaluated

 Some POCs should have local limits regardless of

• utcome of headworks loading analysis

 Consider if removal of any local limit may encourage

increased discharge of pollutants

52

How do you calculate removal efficiencies?

 Concentration-based

 Local Limits Guidance (2004)  3 methods presented  Does not account for flow

53

What are the removal efficiency calculation methods?

Method Definition Advantages Disadvantages ADRE* Paired influent and effluent data lagged by hydraulic residence time

• More accurate by

following plug of water through entire treatment

• Needs at least ten

data pairs to be accurate

• Does not identify

frequency MRE* Difference of averages of influent and effluent data

• Does not required

paired data – more flexible

• Sample collection

time bias Decile Paired influent and effluent data lagged by hydraulic residence time to determine frequency

• Shows how

frequently removal efficiency occurs

• Needs at least

nine data pairs

• Selection of

applicable decile

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* Can be calculated using wastewater or biosolids data for conservative POCs

How do you calculate removal efficiencies?

 Concentration-based

 Local Limits Guidance (2004)  3 methods presented  Does not account for flow

 Load-based

 Accounts for flow variation

 Provides credit for recycled water

 Use similar calculation methods for concentration-

based

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What’s the difference?

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Pollutant Plant E (20% water recycling) Plant F (50% water recycling) Conc. Load Conc. Load Arsenic 25% 36%

• 4%

47% Cadmium 89% 90% 90% 94% Chromium 66% 71% 70% 84% Copper 93% 94% 85% 92% Lead 95% 96% 91% 95% Mercury 99% 100% 98% 99% Nickel 32% 42% 10% 54% Silver 96% 96% 96% 98% Zinc 70% 75% 89% 95% Removal efficiencies based on Mean Removal Efficiency Method

How are MAHLs calculated?

 Use equations to calculate allowable headworks

loading (AHL) using each operational/ environmental restriction

 Removal efficiencies  Operational/environmental restriction  Flow

 Select lowest AHL  MAHL

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POTW EFF NPDES NPDES

R Q C AHL × × = 34 . 8

Is there a need for a local limit?

 Comparison of influent POC loads to MAHL

 Average influent load > 60% of MAHL  Maximum influent load > 80% of MAHL  Monthly average influent load for BOD, TSS,

ammonia > 80% of design capacity (prior 12 months)

 Consider evaluating data on a 12-month basis to

identify influent load trends for POCs

 If at least one criterion is met, local limit for POC

needs to be updated/developed

 Recommend local limits for national POCs (min)

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Example MAHL Calculation

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Instantaneous Max. Discharge Loading Limit lbs/day 164 0.00834*AM5*AM27/(1-AM17) Daily Maximum Discharge Loading Limit lbs/day 66 0.00834*AM5*AM28/(1-AM17) 6-Month Median Discharge Loading Limit lbs/day 16 0.00834*AM5*AM29/(1-AM17) Activated Sludge Inhibition Loading Limit lbs/day 54 0.00834*AM4*AM30/(1-AM18) Anaerobic Digestion Inhibition Loading Limit lbs/day 23 0.00834*AM20*AM31/AM17 Biosolids 40 CFR Part 503 Loading Limit lbs/day 19 0.000001*AM21*AM32/AM17 Biosolids CCR Title 22 Loading Limit lbs/day 484 0.000001*AM21*AM33/AM22/AM17 Allowable Headworks Loading Limits

How do you calculate MAILs?

MAHL = maximum allowable headworks loading SF = safety factor LB = background (non-regulated) pollutant load HW = hauled waste load GA = growth allowance

60

( )

) ( 1 GA HW L SF MAHL MAIL

B

+ + − − × =

All values in lb/ day

MAIL portion of pollutant pie

Background (non- regulated) Regulated Growth Hauled Waste Safety Factor

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How to document local limits update/development effort?

 Selection process for POCs  Assumptions and data used  Calculations

 Removal efficiencies  MAHLs  MAILs

 Next steps

 Public participation  Submittal to Regional Water Board for review (and

approval)

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Are there substantial changes (40 CFR Part 403.18)?

 Substantial change

 Relaxation of local limits (including removing local

limits)

 Reallocation of existing MAIL is not substantial  Must receive Regional Water Board approval before

implementation

 Non-substantial change

 Notify Regional Water Board at

least 45 days before implementation

63

Update/Develop Local Limits Implement Local Limits Evaluate Local Limits

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How are local limits implemented?

 Update Sewer Use Ordinance  Implement in wastewater discharge permits

 Concentration or mass limits allocated from MAIL  Four MAIL allocation methods discussed in Local

Limits Guidance

 Best Management Practices (BMPs)

65

How are MAILs allocated?

 Uniform limits  Discharger contribution-based limits

 Flow proportion  Mass proportion

 As-needed loading  Creative allocations

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Whichever method(s) selected, MAIL cannot be exceeded.

What are uniform limits?

 MAIL is allocated such that all dischargers have

the same concentration limit

 Advantages

 Easily administered

 Disadvantages

 Allocates capacity to

dischargers that may not need it

 May be overly

stringent

67

What are contribution-based limits?

 Dischargers not contributing pollutant load

assumed to be background and MAIL distributed proportionally to dischargers contributing pollutant load

 Advantages

 Provides MAIL to dischargers that need it

 Disadvantages

 May discourage improvement of effluent quality from

discharger

 More difficult to administer since limits would be

different from discharger to discharger

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What are as-needed loading limits and creative allocations?

 Various flexible options for allocating MAIL to

dischargers to provide capacity to dischargers that need it

 May discourage improvement of effluent quality

from discharger

 More difficult to administer since limits would be

different from discharger to discharger

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Use Common Sense

 Compare regulated

discharger data with proposed local limits

 Can discharger meet

proposed local limits?

 If not, determine technical

feasibility of achieving local limit, review discharger data, and/or consider alternative allocation methods

70

Local limits next steps

 Conduct periodic compliance monitoring  Consider developing on-going sampling program

for local limits purposes

 Collection system  Between treatment processes

 Re-evaluate local limits periodically

71

Local Limits Troubleshooting

72

How to deal with blank contamination?

 Importance of sample blanks

 Verify clean sampling techniques or equipment  Verify clean analytical techniques

 Are sample results > 10x blank result?

 Yes – data are OK to use without qualification  No

 Qualify data as non-detect at result level  Modify sample result to account for blank contamination

result

73

How to deal with blank contamination?

 How much of the data are affected?

 Some – data likely OK to use  Lots – consider resampling

 Remember that high quality data are needed to

accurately characterize wastewater and calculate local limits

74

What if there are negative removal efficiencies?

 Don’t dismiss them as errant  Is this chemical used in the treatment process?  Is it a byproduct of treatment?  Could be a consequence of sampling

methodology (e.g., hydraulic residence time)

 Provides another layer of safety in designing

local limits

75

What flow to use?

 Generally use average daily flow over full

calendar years

 Removal efficiency calculations

 Pair influent/effluent flows with corresponding

concentrations on sampling date

 Between processes flow data may not be available

 AHL calculations

 Use corresponding flow data for the operational/

environmental restriction (e.g., influent or primary effluent flow for activated sludge)

76

What flow to use?

 Design flow rate vs. actual flow rate

 Use actual flow rate to prevent overallocation of

available capacity for POC

 If actual flow rate used, can ignore growth allowance

factor in MAIL calculation

 Design flow rate can be used to determine overall

capacity for a POC

77

Photo credit: Environmental Science & Engineering Magazine

What if there’s insufficient available MAIL?

 How does it happen?

 Large non-regulated discharger load  Low removal efficiencies  Safety factor selection

 Where do you commonly see it?

 Cu/Zn nitrification inhibition levels  Conventional pollutants (e.g., BOD, TSS, ammonia)  Salts (e.g., TDS)

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What if there’s insufficient available MAIL?

 Cu/Zn

 Consider using primary treatment effluent data if it is

higher at concentrations that don’t cause upset

 Conventional pollutants

 Is treatment plant able to handle current load?  Uses capacity which can limit future growth

 Might tax equipment designed for higher flows  Consider regulating with sewer rate surcharges

79

What if there’s insufficient available MAIL?

 Salts

 Impacts ability to recycle water  Drought impacts

 Groundwater supply

 Source identification and reduction

 Water supply sources  Water softeners  Laundries

 Pollution prevention and public education

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Summary

 Local limits are required for Pretreatment

Programs

 Local limits need to be periodically reviewed,

evaluated, and updated

 Site-specific high quality data are needed  Site-specific high quality data are needed  Develop an adaptive management approach to

make this process as self-sufficient as possible

81

Local limits are an ongoing process

Implement Local Limits Evaluate Local Limits Update/Develop Local Limits

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Questions?

Presentation available after conference: www.cwea.org/p3s Gorman Lau, P.E. Larry Walker Associates, Inc. GormanL@LWA.com (530) 753-6400

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