Fremont Water Pollution Control Center

OWEA 2013 Annual Conference

June 19, 2013

Plant Expansion for Nutrient Removal and Wet

Weather Flow Treatment

Jeff Lamson, Superintendent, WPCC

Robert Hrusovsky, PE, MWH Americas

Fremont Water Pollution Control Center

1019 Sand Road

Fremont, Ohio

Progression of Improvements at WPCC

Location for New Liquids Process

Plant improvements are being driven by a

Requirement of the Federal Clean Water Act

• Reduce Combined Sewer Overflows (CSO)

• Develop a Long Term Control Plan (LTCP)

• Failure to comply could result in enforcement

action against the City.

Combined Sewer Overflow

Combination of raw sewage and storm water discharged to surface waters.

COMBINED SEWER OVERFLOWS

in Fremont, Ohio

• Fremont’s sewer system is approximately 75%

combined.

• An average of 1 billion gallons of combined

sewage is discharged to the Sandusky River

every year.

• An average of 70 events occur per year.

LTCP Requirements

• June 29, 2006 – OEPA letter to the City stated

that at a minimum 80% solids removal and

disinfection were required.

• However, the City was later told that CSOs

would need to be reduced to no more than 4

events/year and water quality standards would

need to be maintained.

Alternatives

LTC Proposal December 2007

• Treat 9.2 MGD through current facility (with

improvements) and 34.8 MGD through High

Rate Treatment and disinfection. (Total 44

MGD) along with common projects. Total cost

$67.4 million.

• OEPA responded by requiring the City to

conduct a No Feasible Alternatives (NFA) study

to be completed by end of 2010.

No Feasible Alternatives Study (NFA)

• The City had to prove that there were no feasible alternatives to the current proposal that would result in more water being treated biologically, based on technology and the financial capability of the City.

• Finanacial Capability

• Had to show that at least 2.1% of the household median income was being spent on sewer services.

• If not, then other alternatives that would provide additional biological treatment had to be investigated.

Results of NFA

• City could reasonably treat 18 MGD through biological treatment

and 33 MGD through HRT (Total 51 MGD)

• $52.8 million for plant improvements

• Total LTCP cost $78.4 million

• OEPA, due to financial capability, felt the City could treat 24 MGD

through biological treatment and 36 MGD through HRT. (Total 60

MGD)

• Wanted this completed at the same time at a cost of $67.4

million for plant improvements

• Total LTCP cost $94.4 million

• Current rate schedule puts the cost at 2.06% of household median

income

Current Plan after Negotiations with OEPA

• Build new 24 MGD biological process with new Class A solids handling facility for an estimated $57 million.

• The City has two years to determine if any additional treatment is necessary to meet the CSO requirement of 4 or less events per year.

• Conduct common projects to reduce the amount of storm water to be treated.

• Reduce Inflow and Infiltration (County monitoring and surcharge program).

Why Build a New Facility?

• Engineer’s estimate based on life cycle costs

was $1.4 million less to build new than renovate

old and bring up to code.

• Build new with today’s technology and

specifications to treat 24 MGD rather than hope

the old would meet NPDES requirements.

• Better position the City for future growth and

regulations.

Structural issues with existing basins.

Advantages of the New Facility

• Biological Nutrient Removal

• Help with algae blooms in Lake Erie

• Reduce biosolids production – lower operating costs

• Class A biosolids

• More options for use

• Environmentally safer

• Lower or eliminate disposal costs

• currently > $200,000/year

• More energy efficient

Plant Project

• Design firm – MWH Americas, Cleveland Office

• Construction Manager at Risk (CMAR) – MWH

Constructors and Mosser Construction Inc. • New law allowing CMAR went into effect April 2012

Advantages to CMAR

• Lower number of change orders

• Less liability for City

• Process makes it easier to hire local firms

Influent Screen / Pump Station

Screening System

• Manual Coarse Screen (3”

spacing to protect

mechanical screen from

large objects)

• Mechanical Bar Screen

(1/4” spacing)

• Manual Bypass

• Reversing Conveyor

• Screening

Washer/Compactor

• Dumpster

Influent Pumps

• Submersible

• Split wet well for maintenance.

• Multiple pump sizes with VFD’s

for wide range of flow

– 2-3 MGD

– 1-6 MGD

– 2-12 MGD

– Space for future pumps

• Dump discharge piping

connection for flushing out wet

well (resuspend grit)

Influent Pumps

• Dual force mains 24” and 36” for wide range of flow

and future flow

• Flow meters on each force main

Grit Removal

• Submerged Vortex Grit

Concentrator Type System

• 2 Units each rated for 15 MGD

• Space for 2 future units

• Grit pumps in basement

• Flushing water at pump suction

for grit suspension

• Two grit separation/washing

units. Water goes back to

treatment by gravity.

A2O System. Anaerobic/Anoxic/Oxic

• Biological treatment /

Internal recycle.

• Floating Mixers

• Fine bubble diffusion

system

• Internal recycle with

submersible pumps

• Multiple blowers with

turndown capability

• ORP and DO sensors

for control.

Surface

Mixers Fine Bubble

Air Diffusers

Recirculation

Pumps

Process Alternatives Evaluated

• Membrane Bioreactor (MBR)

• Integrated Fixed-film Activated Sludge (IFAS)

• Oxidation Ditch

• Three-stage (A2O) biological nutrient removal (BNR)

activated sludge

• Vertical Loop Reactor (VLR)

Alternative Evaluation Criteria

• Compatibility with existing site constraints

• Constructability

• Use of existing facilities

• Operation during construction

• Proprietary licensing

• Construction time

• Wet weather performance

Alternative Evaluation Criteria

• Ease of operation

• Maintenance requirements

• Expandability

• Sidestream (screenings, grit, residuals) impacts

• Energy consumption

• Compliance with nutrient removal regulations

• Odor control

Alternative Evaluation Scoring

• Membrane Bioreactor 395

• IFAS 523

• Oxidation Ditch 502

• Three-stage A2O BNR 558

• Vertical Loop Reactor 481

Why Three-Stage A2O was Selected

• Easy to integrate to the existing site

• Meets current regulatory limits

• Prepares Fremont for future nutrient removal

requirements (TP and TN)

• Minimal number of bio-reactors

Why Three-Stage A2O was Selected

• Simple operation

• Can accommodate peak wet-weather flows (step-

feed operation)

• Lower aeration (energy) requirements

• Minimal impact to existing operations

• Primary sedimentation is not required

Final Clarifiers

• 3 at 90 ft diameter

• 18’ deep (ability to store solids)

• Energy Dissipating Inlet (EDI)

• Density Current Baffles

• RAS pump dedicated to each clarifier with flow meter.

Tertiary Filter

• Rotating Disc Filter

• Automatic backwash

• Over double the treatment capacity in half the footprint

• Mudwell to collect backwash and send to A2O influent

Disinfection

• Ultraviolet (UV) system

• 2 Channels 12 MGD

each

• 1- Bypass Channel

• Canopy Overhead

• Peracetic acid as

backup / power outage

Effluent Pump Station

• Multiple variable speed

submersible pumps

1 - 3 MGD

2 - 6 MGD

2 - 9 MGD

• Flow to river by gravity

until pre-determined river

level then turn on pump

station.

Chemical Systems

• Settling aid polymer

• Aluminum Chlorohydrate

(ACH) for phosphorous

removal

• Peracetic acid for RAS

filaments and backup

disinfection

• Polymer for thickening

and dewatering

centrifuges

• Room for future chemical

Solids Processing

• Autothermophilic Aerobic Digestion (ATAD)

• Gravity thickener

• Thickening centrifuge

• ATAD

• SNDR

• Biofilter

• Dewatering centrifuge

(liquid or solid Class A product)

Overall Site Plan

Permanent

Grit Pad

Septage

Receiving

Manhole

Proposed Construction Phasing

Demolition / Dewatering

Equip.

Piling

Liquid Phase

Solids Phase

(Mar 13’ – June 13’)

(July 13’ – Feb 15’)

(June 13’ –

Aug 13’)

(Mar 15’ – Dec 15’)

*Use Existing Aeration Tanks for Temporary Aerobic Digestion

Questions?