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KING’S BEACH �BASIS OF DESIGN STUDY��ALTERNATIVE SELECTION MEETING

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October 3, 2022

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OVERVIEW

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Comparison of Key Metrics

Alt #

Description

Capital Cost*

Net Present Value*

Implementation Duration

% Beach Days Open

Peak Flow Capacity (MGD)

3

Chemical Disinfection

$27,000,000

$25,400,000

3.3 years

90%

5

4

UV Disinfection

$24,952,400

$23,346,000

3.1 years

97%

15

5

Extend Outfall

$55,800,000

$47,000,000

8.8 years

94%

10

* Cost estimates are reflective of this stage of design and therefore include 50% contingency

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Life Cycle Analysis Metrics*

Alt #

Description

Capital Cost

Salvage Value in 2042

Salvage Present Value

Annual O&M

O&M Present Value

Net Present Value

3

Chemical Disinfection

$27,000,000

$5,070,000

$4,680,000

$160,000

$3,070,000

$25,400,000

4

UV Disinfection

$24,952,000

$5,272,000

$4,868,000

$170,000

$3,261,000

$23,345,000

5

Extend Outfall

$55,800,000

$7,580,000

$7,000,000

$20,000

$340,000

$49,000,000

* Cost estimates are reflective of this stage of design and therefore include 50% contingency

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Alternatives Screening Comparison

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Advantages and Disadvantages

See Handout

Basis for Recommendation

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OPEN DISCUSSION

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Next Steps

  • Endorsement of Solution (City of Lynn, LWSC, Swampscott)
  • Report Development
    • Peer Review and Updates
  • Funding
    • ARPA
    • Bipartisan Infrastructure Law
  • Implementation Steps
    • Pre-Design (additional sampling; flow / level; piloting)
    • Preliminary Design
    • Final Design & Permitting
    • Construction

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BACKUP SLIDES

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Alternative 3 – Chemical Disinfection

  • Conceptualized Layout at Town-Owned Lot on New Ocean Street
  • Increased Building size to 1,430 SF
  • Transitioned to a more typical “CSO” treatment approach
    • Chlorine Contact Tank (30 mins hold time)
    • Screening and Grit Removal
  • Contact Tank reduces annual chemical expenses (higher hold time -> lower dose)
    • Eliminates need for additional dechlorination site.
  • No Standby Power

UPDATES TO ALTERNATIVE

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Alternative 3 – Chemical Disinfection

UPDATES TO ALTERNATIVE

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Bar Screen Section View

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Chlorine Contact Tank

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  • Conceptualized Layout at Town-Owned Lot on New Ocean Street
  • Building Footprint increased to 1,550 SF
  • Added Hydrodynamic Separator
  • Reduced bar screen channels from 2 to 1
  • Updated Construction Cost and Life Cycle Cost
  • No Standby Power

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UPDATES TO ALTERNATIVE

Alternative 4 – UV Disinfection

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UPDATES TO ALTERNATIVE

Alternative 4 – UV Disinfection

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UV

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Alternative 5 – �Outfall Extension

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  • Conceptualized Flow Control Structures and Overall Layout
  • Added Tide Gate Structure
  • Added Pretreatment/ Sedimentation Trap

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UPDATES TO ALTERNATIVE