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2011 OWEA Wet Weather Issues Webinar Series

Curtis D. Courter, P.E.

Webinar Topics

Background

Treatment Alternatives

Solids and Floatables Control

Disinfection Alternatives

Clarification○ EHRT

○ HRPCT

Background - CSOs

Discharge untreated sewage diluted with rainwater to local waterways (CSO)

Water quality & human health impacts

National issue

85 Ohio communities w/ combined systems

Over 1300 CSOs

Source: City of Wilmington Delaware

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Background – Water Quality

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20

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60

80

100

120

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160

Str

eam

/Riv

er M

iles

(100

0s)

Source: iaspub.epa.gov

Background - Regulatory

CSO Control Policy

Clear levels of control

Flexibility

Phased implementation

Review and revision WQS

Nine Minimum Controls

NPDES Permits

Consent Judgments

Webinar Topics

Background

Treatment Alternatives

Solids and Floatables Control

Disinfection Alternatives

Clarification○ EHRT

○ HRPCT

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Why Solids and Floatables Control? Nine Minimum Controls

Control of solids & floatables materials in CSOs (NMC 6) Pollution prevention to reduce contaminants in CSOs (NMC 7)

Narrative Water Quality Standards Waters shall be free from floating materials entering as result

of human activity in amounts to be unsightly or cause degradation – OAC 3745-1-04B

Pollution Discharge Elimination Permits None as a result of discharge in unnatural quantities injurious

to designated use - MI0022802 Consent Orders

Engineering study of past , current and future measures to control solids and floatables materials – Cincinnati MSD

Assess construction of facilities for removing floatables from CSOs as an element of LTCP – Toledo

Solids and Floatables Controls

Source controls

In-System controls

End-of-Pipe controls

Source Controls

Pollution prevention

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Source Controls

Catch basin modifications

Source Controls

Filters

In-System & End-of-Pipe Controls

Simple bar racks Simple bar racks

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In-System & End-of-Pipe Controls

Static baffles

In-System & End-of-Pipe Controls

Dynamic baffles

In-System & End-of-Pipe Controls

Mechanically cleaned screens

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In-System & End-of-Pipe Controls

Proprietary controls

Hydrodynamic separators

Nutrient Separating Baffle Box

Others

End-of-Pipe Controls

Nets

End-of-Pipe Controls

In Receiving Water - Nets

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End-of-Pipe Controls

In Receiving Water - Booms In Receiving Water - Booms

Case Study - Sanitation District No. 1 SD1 Program Options

Regulatory:○ S&F Controls everywhere

Other Communities:○ Pilot engineered controls

Hybrid:○ Simple S&F w/ engineered controls

Pilot program developed

Hydraulic criteria, controls, inspection forms

Cincinnati

Simple S&F Controls – Bar Racks & Baffles

Dry Weather Flow

SumpOutfall

Pleasant Street

4th StreetBaffle

Weir

Outfall

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Simple S&F Controls – Net Bags

Net Bags

Elevated Outfall Pipe

Engineered S&F Control

Baffle

Outfall

NSBB

Screen

Sediment Sumps

Sewer

Select Observations – Bar Racks

Natural Debris

InfluentOutfall

Blocking

Rack Overtopping

Influent

Outfall

Blocking Tie-off

Overtopping ~ 6 month storm event

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Select Observations – Baffles

Baffle

OutfallInfluent

Baffle Overtopping

Outfall

Blocking Tie-off

Influent

Overtopping ~ 6 month storm event

Select Observations – Nets (Logged Changes)

Mary Ingles

5 lbs (12/4/07)

6 lbs (12/5/07)

1½ lbs (12/11/07)

8 lbs (12/26/07)

5 lbs (6/19/08)4 lbs

5 lbs8 lbs

Pilot S&F Control Pilot Program

Summary of findings:

Bar racks ineffective due to blinding and height limitations due to hydraulic restrictions

Weirs and baffles marginally effective – need good hydraulics at CSO diversion (check velocity under baffle)

Nets on elevated overflow outfall pipes highly effective as long as velocities are not too high (damage nets)

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Final S&F Control Program

Install simple controls (weirs/baffles and nets) where configuration and hydraulics allow and effectiveness anticipated

Engineered control locations would be through watershed planning

Source controls – public education, street cleaning, catch basin modifications & cleaning, grit pits, regulate construction site runoff

Webinar Topics

Background

Treatment Alternatives

Solids and Floatables Control

Disinfection Alternatives

Clarification○ EHRT

○ HRPCT

E ffect on C l2 D ose in R egression Models

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1 10 100 1,000 10,000 100,000 1,000,000

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g F

. C

oli

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uc

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n

4 m g/l - Cl2

8 m g/l - Cl2

10 m g/l - Cl2

20 m g/l - Cl2 SpringCrk. (1997)

6 m g/l - Cl2

D .T . = 4 m inutesTKN = 3 .6 m g/lBO D = 31.5 m g/l

Source: Combined Sewer O verflow Abatement Program , Rochester, N Y V olume II.

Pilot Plant Evaluations (EPA 600/2-79-031b)

E ffect on C l2 D ose in R egression Models

0

1

2

3

4

5

1 10 100 1,000 10,000 100,000 1,000,000

GT

Lo

g F

. C

oli

. R

ed

uc

tio

n

4 m g/l - Cl2

8 m g/l - Cl2

10 m g/l - Cl2

20 m g/l - Cl2 SpringCrk. (1997)

6 m g/l - Cl2

D .T . = 4 m inutesTKN = 3 .6 m g/lBO D = 31.5 m g/l

Source: Combined Sewer O verflow Abatement Program , Rochester, N Y V olume II.

Pilot Plant Evaluations (EPA 600/2-79-031b)

High Rate Disinfection

Application of disinfectants using high-rate mixing as a substitute for contact time

Kill = C x G x T

Where: T ≤ 5 minutes

Applies to chemical disinfectants

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Disinfection Methods

Ozone

Chlorine Dioxide

Gaseous Chlorine

Calcium Hypochlorite

UV

Sodium Hypochlorite

Peracetic Acid

BCDMH (bromine)

Disinfection Methods

Ultra Violet (UV) Physical disinfectant

Common Elements Pretreatment Power center Lamps Ballast Cleaning System Gates (level control & Isolation) Instrumentation (transmittance, etc.)

Disinfection Methods Sodium Hypochlorite (NaOCl)

Chlorine based solution Common Elements

Storage tanks Transfer pumps Day tanks Feed pumps Mixers / diffusers Instrumentation (flow, TRC, ORP, TSS) Sampling equipment Dechlorination

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Disinfection Methods

Peracetic Acid (PAA) Acetic Acid and Hydrogen Peroxide solution

Common Elements 275 gallon totes or 55 gallon drums Feed pumps Mixers / diffusers Instrumentation (flow, TSS) Sampling equipment Pressure relief Heat monitoring

Disinfection Methods Bromochlorodimethylhydantoin (BCDMH)

Bromine based powder Common Elements

BCDMH Unit○ Storage hopper○ Feed equipment○ Dissolution equipment

Feed pumps Mixers / diffusers Instrumentation (flow, TSS) Sampling equipment

Courtesy of City of Akron

Case Study – Conner Creek

Retention Treatment Basin

NPDES Permit Requirements

5 minute detention time @ 10-Yr peak flow○ 30 MG @ 13,262 CFS

Fecal coliform limits○ 400 cfu/100 ml daily

○ 200 cfu/100 ml monthly

TRC goal < 1 mg/L

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Disinfection System Studies

Disinfection Pilot Study

Mixer Modeling

NaOCl Degradation

Study

NaOCl Feed System Control Study

Disinfection Pilot Study

Objectives Determine dose vs. kill relationship Determine effect of mixing technology on kill

Disinfectant Sodium hypochlorite

Technologies Tested Vertical shaft Pumped diffusion High speed submersible induction G ~ 500 sec-1

Disinfection Pilot Study

Conclusions

Mixing technology:○ Mixers are equivalent for equivalent G

○ Rapid and thorough mixing is critical

CxT = 125○ ≥ 4 log fecal coliform reduction

○ ≤ 400 cfu/100 ml

Submersible induction mixers selected

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Mixer Modeling

High speed submersible mixers

Between 4 and 8 mixers required per channel

Objectives Determine the number of mixers

3 Mixers Tested 2 Manufacturers, vacuum and non-vacuum

styles

Rhodamine WT tracer

Mixer Modeling

Conte Anadromous Fish Research Center

Testing Channel

Mixer ModelingSampling Station 1

10 Feet Downstream of Mixer

Sampling Station 258 Feet Downstream of

MixerSample Pumps

Sampling Grid

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Mixer Modeling

0.25 Normalized Cl2 Contours Measured 10 Feet Downstream of Mixer At 3.2 FPS

Mixer Modeling0.1 Normalized Cl2 Contours Measured 58 Feet Downstream of Mixer At 2.7 FPS

Mixer Modeling

Conclusions

Secondary Mixing Enhances Dispersion

Six Mixers Per Channel

Additional Disinfectant Needed At Bottom of Channel

Contact Basin Starts Approx. 58-Feet Downstream of Mixers

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Operational Observations From 2-Year Intensive Monitoring* 46 activations & 25 discharge events

Captured 2.5 billion gallons and discharged another 2.9 billion gallons of treated effluent

Max effluent flow ~2,600 cfs (T~25 min.)

Over 13-1/2 days of overflow

Recently had an event lasting 8 days

*DWSD 2008, Conner Creek CSO Basin Evaluation, October 24, 2008.

Webinar Topics

Background

Treatment Alternatives

Solids and Floatables Control

Disinfection Alternatives

Clarification○ EHRT

○ HRPCT

High Rate Clarification Alternatives Chemical (non-proprietary)

CEPT

EHRT

Physical-Chemical (proprietary)

CoMag / BioMag

Densadeg

Actiflo / Bio-Actiflo

Windsor Ontario EHRT Pilot Plant

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Chemically Enhanced Clarification CEPT / EHRT

Addition of coagulant and polymer Aggregates particles (flocculation)

Common Elements Screens Grit chamber Settling tank Chemical feed system Mixers Baffles Instrumentation, pumps, piping, etc.

Physical-Chemical Clarification

Densadeg Degremont Technologies Recycled sludge ballast Polymer

Common Elements Screens Reactor Rapid Mixer Lamella tubes Instrumentation, pumps, piping, etc.

Physical-Chemical Clarification

Actiflo / Bio-Actiflo Microsand ballast Polymer

Common Elements Fine screens Hydrocyclones Rapid Mixer Lamella plates Instrument., pumps, piping, etc.

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Physical-Chemical Clarification

CoMag / BioMag Cambridge Water Tech. Magnetite ballast Polymer

Common Elements Feeder / hopper Mix tank Mixers Shear mill and magnetic separator Ballast make up Instrumentation, pumps, piping, etc.

Case Study – NYCDEP Jamaica Tribs CSO Project NYC Actiflo & Densadeg side-by-side

pilot

Unit No. ofRuns

Flow (mgd)

HRT (min)

FeCl3 (mg/L)

Polymer (mg/L)

SOR (1000s -gpd/ft2)

Startup Time (min)

Densadeg 17 0.2-0.5 12-33 50-70 1.4-1.8 29-65 30-60

Actiflo 15 0.3-0.8 5-11 60-100 0.45-1.0 72-130 5-10

Unit Waste Sludge TSS (%)

Influent TSS

(mg/L)

Effluent TSS

(mg/L)

TSS Removal

(%)

Influent BOD5(mg/L)

Effluent BOD5 (mg/L)

BOD5 removal

(%)

Densadeg 1-10% 83 25 69% 151 63 58%

Actiflo 0.1-0.3% 106 16 84% 119 51 57%

Questions?

Thank YouCurtis D. Courter, P.E.Hazen and Sawyer, P.C.ccourter@hazenandsawyer.comwww.hazenandsawyer.com(513) 469-5115 – Office(513) 833-5125 - Mobile