City of Ouray Wastewater Treatment Plant Master...

City of Ouray Wastewater Treatment Plant Master Plan / Capacity Study

Leanne Miller, P.E.

December 17, 2018

2

Introduction

• Recap from August – Wastewater Treatment Capacity Study – Capacity – Existing Facility Evaluation

• Recommended Improvements • Proposed Wastewater Treatment Plant • Decision Matrix • Preliminary Project Schedule • Funding Mechanisms

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Wastewater Treatment Capacity Study

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Review WWTP History & Records

Current and Future Capacity

Assess Existing WWTP

RecommendedImprovements

Master Plan

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Recap

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55

Current and Future Capacity – Flow Projections

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Current and Future Capacity – Loading Projections

1,170 lbs/day

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Wastewater Treatment Capacity

Parameter Flow(MGD)

Loading(lb/day)

Existing Max Month Average 0.266 367

Current Capacity

Summer 0.363 400

Winter 0.250 275

Projected Max Month Average 0.364 515

Buildout Capacity 0.465 6591,170

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Wastewater Treatment Capacity

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• The 1993 expansion project increased the design capacity of the system to 0.363 million gallons per day (MGD) (summer months)

• Per Colorado Department of Public Health and Environment (CDPHE) standards, a plant expansion is required once a plant reaches 80% of design capacity. – At 95% capacity the expansion must be inconstruction

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Existing System – Preliminary Treatment

• Screening not effective – damages mechanical equipment in lagoons

• Grit chamber not effective – accumulates along lagoon and likely depositing in lagoon

• Concrete deterioration – prolonged exposure to hydrogen sulfide

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• Insufficient aeration capacity– Does not meet CDPHE criteria

• Odor issues • History of effluent violations – CBOD and TSS

• No instrumentation for process control • Lagoon liners past life expectancy

– do not meet current CDPHE design criteria

• Insufficient volume – Does not meet CDPHE criteria

• Future ammonia limits

Existing System – Secondary Treatment

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Existing System – Disinfection/ Dechlorination

• History of effluent violations for e. coli

• No automation or redundancy of chemical feed systems

• Insufficient storage for CDPHE design criteria

• Inadequate contact time at former injection point

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Existing System – Ancillary Systems

• Electrical service is insufficient for additional capacity

• SCADA system and I&C are outdated and no longer supported by the manufacturer

• Generator is likely undersized for future capacity

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Recommendations

• New WWTP • Limit organic loading to existing facility • Develop an industrial pretreatment program • Inflow and infiltration study/ collection system evaluation

• Potable water meters• Rate study

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Proposed WWTP

• Preliminary treatment • Influent equalization and pump station • Secondary treatment • Disinfection • Solids handling • Electrical, I&C, and SCADA • Relocating public works facility

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WWTP – Design Criteria

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Parameter Unit Influent EffluentFlow MGD 0.47 0.47 MGD

BODmg/L 300 15 mg/L (85% removal)

lb/day 1,170 NA

TSS mg/L 300 15 mg/L (85% removal)

TDS mg/L 700 Report Only Ammonia Nitrogen mg/L 40 < 1 mg/L Total Phosphorus mg/L 8 ‐‐‐Total Inorganic Nitrogen mg/L 40 ‐‐‐Total Kjeldahl Nitrogen mg/L 50 ‐‐‐

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WWTP – Preliminary Treatment & EQ

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WWTP – Preliminary Treatment & EQ

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Headworks Influent EQ / IPS

Headworks, EQ, & IPS

$1.5 million ‐ $2 million

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WWTP – Disinfection

Disinfection – UV disinfection

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WWTP – Disinfection

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UV Disinfection

$550,000 ‐ $1 million

Influent EQ / IPS

Headworks

UV Disinfection

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WWTP – Solids Handling

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21

WWTP – Solids Handling

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Solids Handling

$1 million ‐ $2 million

UV Disinfection Solids Handling

Influent EQ / IPS

Headworks

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WWTP – Secondary Treatment Alternatives

• Integrated Fixed Film Activated Sludge (IFAS) Treatment System

• Aerobic Granular Sludge (AGS)• Sequencing Batch Reactor (SBR)• Moving Bed Biofilm Reactor (MBBR)• Aeromod / Sequox (similar process to conventional activated sludge process)

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23

WWTP – Secondary Treatment Alternative 1

Alternative 1 – SBR

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Advantages• No recycle streams – reduces operational complexity • Suited for intermittent flow conditions• No secondary clarifier • Minor modifications required to increase nutrient removal

Disadvantages• Cycle structure more complex than MBBR (Alternative 2)• Operators must adjust wasting depending on performance and

biological conditions• Post EQ required for continuous flow to UV• Largest footprint

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25


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UV Disinfection Solids Handling

Influent EQ / IPS

Headworks Public Works Facility

Process Building

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Alternative 2 – MBBR

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Advantages Smallest footprint Increase capacity by increasing media in the basin No wasting process, reduce operations complexity In basin equipment is stainless steel – no anticipated in basin

maintenance Lowest capital cost (if exclude a redundant basin) Lowest annual and 20‐year O&M costs

Disadvantages Higher hydraulic losses – screen between basins Internal recycle required to achieve increased nutrient removal Requires chemical addition at disk filter for TSS removal

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UV Solids Handling

Influent EQ / IPS

Headworks


Process Building

Public Works Facility

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Alternative 3 – Sequox

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3030

Advantages All equipment accessible from top of basin No moving parts below water surface Ideal for variable hydraulic and organic loading Less operator attention than traditional CAS processes

Disadvantages Requires return and waste activated sludge pump station Highest energy requirement Highest annual O&M costs Highest capital cost


3131

UVSolids Handling

Influent EQ / IPS

Headworks


Process Building

Public Works Facility

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Proposed Project Summary and Assumptions

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• All processes inside a building• Headworks, solids processing, and secondary treatment building all separate structures

• Building materials (Gateway to Ouray) – CMU • Upgraded electrical service included • New emergency generator is included• Public works facility included • Decommissioning of the existing lagoons and biosolids disposal is included.

• Dewatering during construction is included

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Opinion of Probable Cost

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• Cost estimates have a nominal accuracy of +/‐ 30% • Contingency = 20% • Contractor Overhead and Profit = 15% • Construction Cost versus Total Cost

• Design Services (engineering, geotechnical, surveying, permitting) = 8%

• Bidding and Construction Services = 5% • Legal and Administrative Fees = 2%

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WWTP – Capital Costs

$1.5 ‐ $2.0 million

$1.0 ‐ $2.0 million

$550K ‐ $1.0 million

$1.5 – 2.0 million

Construction CostsAlt 1 = $13.6 million Alt 2 = $13.2 millionAlt 3 = $14.4 million

Total Project CostsAlt 1 = $15.6 million Alt 2 = $15.2 million Alt 3 = $16.6 million

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WWTP – O&M Costs

Alt 1: SBR Alt 2: MBBR Alt 3: SequoxAnnual O&M Cost $249,200 $227,500 $303,60020‐year O&M Cost $5,192,800 $4,607,700 $6,147,500

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• Class B operator required for each alternative • Solids disposal • Chemical cost (Alt. 2) • Energy

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Criteria Weight

Operability 20%Process Performance 20%Aesthetics 15%Constructability 5%Footprint 10%Capital cost 15%O&M cost 15%

TOTAL 100%

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How do we decide?

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Decision Matrix Scoring

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Criteria Weight Alt 1 SBR

Alt. 2MBBR

Alt. 3Sequox

Operability 20% 3 4 2ProcessPerformance 20% 3 4 2

Aesthetics 15% 3 5 4Constructability 5% 4 5 5Footprint 10% 3 5 4Capital cost 15% 5 3 3O&M cost 15% 4 5 2

TOTAL 100% 2.9 3.5 2.4

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Project Delivery and Proposed Schedule

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January 2019 Begin

Funding Process

Preliminary Design

June 201930% Design

Site Application –CDPHE

Ouray County Permitting

July 2019 Advertise for

CMAR

October 2019

60% Design PDR –CDPHE

January 2020 100% Design

GMP

April 2020 Begin

Construction

July 2021 Construction Complete

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Project Delivery and Proposed Schedule

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Start Date Completion Date Prepare and submit SRF Prequalification Application January 1, 2019 January 10, 2019 Prepare and submit Project Needs Assessment January 10, 2019 March 31, 2019 Survey and Geotech Subcontractors Conduct Field Investigations for Design (weather depending) March 10, 2019 May 1, 2019

Prepare and submit Site Application February 1, 2019 April 30, 2019 Prepare 30% Design Drawings and Specifications April 1, 2019 June 30, 2019 Advertise for CMAR RFP July 1, 2019 NAAward Pre‐Construction Services for CMAR August 15, 2019 NAPrepare and submit Process Design Report June 1, 2019 November 1, 2019 Prepare 60% Design Drawings, Specifications, and Cost Estimate July 1, 2019 October 1, 2019

Prepare 95% Design Drawings, Specifications, and GMP October 15, 2019 January 1, 2020

Award Construction Services CMAR Contract January 1, 2020 NASubmittal Review for Construction January 1, 2020 April 1, 2020 Construction of new WWTP April 2020 July 2021

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Funding

• Taps and User Fees • Bonds• State Revolving Fund Loan • DOLA – Energy and Mineral Impact Grants

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Questions

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Current Capacity

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0.1

0.15

0.2

0.25

0.3

0.35

0.4

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Influ

ent F

low

(MG

D)

Influent Flow

2013 2014 2015 2016 2018

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Current Capacity

0

100

200

300

400

500

600

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

BOD

5(lb

/day

)

Influent Organic Loading

2013 2014 2015 2016 2018

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Future Capacity – Projections

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Land Use Units Built Unbuilt Total Percent Built Out Notes

Single-family units 437 136 573 76 Assumes only platted lots

are developed.Accessory Dwelling

Unitsunits 28 115 143 20

Unbuilt ADUs Based on 20% of Single-family

TotalDuplex Units units 4 0 4 100

Condos, Apts,

Townhomesunits 235 549 784 30

Unbuilt ADUS looking at infill

development/redevelopment/new development

Mobile Homes units 51 0 51 100 Assumes no additional

mobile homes

Residential

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Land Use Units Built Unbuilt Total Percent Built Out Notes

RV Sites units 141 27 168 84 133 with full hook ups;

Camp Sites/Cabins units 36 0 36 100 Water Only with bath

house

Hotel, B&B, Lodging units 563 211 774 73

New hotel units via Twin Peaks, Hot Springs Inn,

etc. (What we know today)

Tourism

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Commercial Land Use Units Built Unbuilt Total Percent Built

Out Notes

Retail ft2 154,238 92,333 246,571 63Unbuilt is first floor of infill

development sites in commercial areas

Restaurant/Bar/Brewery ft2 38,427 38,141 76,568 50

Unbuilt derived by looking at percentage today of

restaurant and bar space to retail area

Office/Professional Service ft2 22,786 22,616 45,402 50

Unbuilt derived by looking at percentage today of

office/professional service to retail area

Light Industrial ft2 42,100 30,000 72,100 58

Fraternal Club ft2 16,402 0 16,402 100Assumes no additional floor area for fraternal

clubs

Government ft2 115,571 0 115,571 100 Assumes no additional government floor area

Church ft2 38,489 0 38,489 100 Assumes no additional churches

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