Bay View WWTP Bay View WWTP ImprovementsImprovements

Citizens Advisory Committee Briefing

May 5, 2003

Today’s AgendaToday’s Agenda

• Introduction• Wastewater Treatment

101• Bay View WWTP

• Flows and Capacities

• NPDES Permit Requirements

• Consent Decree Requirements

• Bay View WWTP• Existing Flow Scenarios

• Future Flow Scenarios

• Proposed Wet Weather Treatment & Retention Facilities• Wet Weather Treatment

• Flow Equalization

• Plant Tour

Wastewater Treatment 101 Wastewater Treatment 101 – Preliminary Treatment– Preliminary Treatment

• Purpose: Removes coarse solids and flotables

• Processes:• Screening• Grit Removal• Skimmings (flotables) Removal

• Also includes swirl concentrators for wet weather treatment• High-rate Grit, settleable solids, and flotables

removal

Wastewater Treatment 101 Wastewater Treatment 101 – Primary Treatment– Primary Treatment

• Purpose: Removes settleable solids, 50-70% of suspended solids, and 25-40% of CBOD

• Process – Primary Settling or Clarification• Provides quiescent conditions in a 10-12 feet deep

basin for 1.5 to 3.0 hours for gravity settling of solids

• Settled solids (i.e. primary sludge) are scraped to a bottom hopper for removal by pumping

Wastewater Treatment 101 Wastewater Treatment 101 – Secondary Treatment– Secondary Treatment

• Purpose: Removes high percentages of CBOD and TSS (greater than 85%)

• Processes – Activated Sludge & Secondary Clarification• Provides 3-5 hours of aerobic conditions in an aeration basin

to promote reduction of biodegradable organic matter

• 12-15 feet deep basin for 1.5 to 3.0 hours for gravity settling of solids

• Settled solids (i.e. waste activated sludge) are scraped to a bottom hopper for removal by pumping

Wastewater Treatment 101 Wastewater Treatment 101 – Nutrient Removal– Nutrient Removal

• Purpose: Removes high percentages of Ammonia Nitrogen and Phosphorus

• Processes – Activated Sludge (ammonia); Chemical Coagulation & Clarification (phosphorus)• Provides 4-8 hours of aerobic conditions in an aeration basin

to promote reduction of ammonia to nitrates and nitrites

• Ferrous chloride and polymer are added in advance of primary clarifiers to remove phosphorus by chemical precipitation

Wastewater Treatment 101 Wastewater Treatment 101 – Disinfection– Disinfection

• Purpose: Destroys or Inactivates Fecal Coliform Bacteria

• Processes – Chlorination/Dechlorination or Ultraviolet (UV) Radiation• Chlorine solution is mixed with secondary effluent

for a minimum of 15 minutes; sodium bisulfite is added prior to discharge to reduce residual chlorine concentration

• Secondary effluent is passed through banks of UV light tubes to inactivate bacteria RNA & DNA

Bay View WWTPBay View WWTP

• 100 mgd Average Design Flow• 45 mgd Dry Weather Flow• 75 mgd Average Annual Flow• Nearly half of the flow treated is from infiltration of

groundwater/inflow of stormwater into sewer system

• NPDES Permit Mass Discharge Limits are based on a maximum flow of 130 mgd

• Peak hourly wet weather flow to the WWTP is approximately 400 mgd

Bay View WWTPBay View WWTP

• Toledo has to meet two sets of requirements:• NPDES Permit Effluent Limits• Consent Decree Requirements

NPDES Permit NPDES Permit RequirementsRequirements

• Effluent concentration and mass discharge limits for: • CBOD

• TSS

• Ammonia (varies seasonally)

• Phosphorus

• Disinfection during the warmer months (April-October).

• Dissolved oxygen concentration must exceed 5 mg/L at all times

Consent Decree Consent Decree RequirementsRequirements• (Advanced) secondary treatment of all flows up to 195

mgd• Retention of excess flows in a 60 million gallon

equalization basin; • All retained flow must receive secondary treatment prior to

discharge• 185 mgd of high-rate physical-chemical treatment

(ballasted flocculation) for excess flows that cannot be treated through secondary treatment or stored

• Does not permit bypassing of secondary or wet weather treatment unless flow exceeds 400 mgd

BAY VIEW PUMP

STATION

GRITREMOVAL

SKIMMINGSREMOVAL

PRIMARYCLARIFIERS

AERATION BASINS

CHLORINECONTACT

BASIN

SECONDARYCLARIFIERS

Outfall001

45-75 MGD

45-75 MGD

DRY AND NORMAL CONDITIONS

BAY VIEW PUMP STATION

SKIMMINGSREMOVAL

PRIMARY CLARIFIERS

Primary SludgeAir

Air

GRITREMOVAL

Grit

Screenings Skimmings

AERATION BASINS SECONDARY CLARIFIERS

CHLORINECONTACT BASIN MAUMEE RIVER

MA

TC

H

LIN

E

MA

TC

H

LIN

E

Waste Activated Sludge

Polymer

Ferrous Chloride

ChlorineSodium Bisulfite

BAY VIEW PUMP

STATION

GRITREMOVAL

SKIMMINGSREMOVAL

PRIMARYCLARIFIERS

AERATION BASINS

CHLORINECONTACT

BASIN

SECONDARYCLARIFIERS

FINESCREENS

SWIRLCONCENTRATORS

Outfall002

Outfall001WET WEATHER CONDITIONS

UP TO305 MGD

168 MGD

137 MGD

UP TO 93-165 MGD

140-212 MGD

BAY VIEW PUMP

STATION

GRITREMOVAL

SKIMMINGSREMOVAL

PRIMARYCLARIFIERS

AERATION BASINS

CHLORINECONTACT

BASIN

SECONDARYCLARIFIERS

FINESCREENS

SWIRLCONCENTRATORS

Outfall002

Outfall001

UP TO400 MGD

168 MGD

137 MGD

UP TO 188-260 MGD

140-212 MGD

UP TO263 MGD

UP TO 95 MGD

EXTREME WET WEATHER CONDITIONS

BAY VIEW PUMP

STATION

GRITREMOVAL

SKIMMINGSREMOVAL

PRIMARYCLARIFIERS

AERATION BASINS

CHLORINECONTACT

BASIN

SECONDARYCLARIFIERS

60 MG EQ BASIN

SCREENING& GRIT

REMOVAL

BALLASTEDFLOCCULATION

CHLORINECONTACT

&REAERATION

EFFLUENTPUMPING

168 MGD

232 MGD

UP TO400 MGD

UP TO400 MGD

UP TO212 MGD

UP TO205 MGD

EXTREME WET WEATHER CONDITIONS

Chlorine

Sodium Bisulfite

Air

CHLORINE CONTACT & REAERATION BASIN

BLENDING WITHSECONDARY EFFLUENT

MAUMEE RIVER

MA

TC

H

LIN

E

MA

TC

H

LIN

E

WET WEATHER TREATMENT

Screenings

GRITREMOVAL

Grit

FINESCREENING

Polymer

Ferric Chloride

BALLASTED FLOCCULATION

WasteSolids

60 MG FLOW EQUALIZATION BASIN

17.33 MG17.33 MG 17.33 MG

4 MG 4 MG

60 MG FLOW EQUALIZATION BASIN

17.33 MG17.33 MG 17.33 MG

4 MG 4 MG

6-20 days6-20 daysPer yearPer year

4-14 days4-14 daysPer yearPer year

2-10 days2-10 daysPer yearPer year

1-3 days1-3 daysPer yearPer year

25 foot maximum25 foot maximumWater depth per Water depth per CompartmentCompartment

180 feet180 feet

260 feet260 feet

220 feet220 feet220 feet220 feet2

40

fe

et

24

0 f

ee

t

36

0 f

ee

t3

60

fe

et

42

0 f

ee

t4

20

fe

et

EQUALIZATION BASIN “FIRST FLUSH” COMPARTMENTS

3-54”INFLUENT

PIPES