city of alexandria and alexandria renew enterprises · presentation outline css stakeholder group...

Combined Sewer System Permit

and Long Term Control Plan Update

CSS Stakeholder Group Meeting #4

February 1, 2018

City of Alexandria and Alexandria Renew Enterprises

• Welcome

• Purpose and Goals

• Green Infrastructure Update

• Summary of CSO Program Options and Performance

• Life Cycle Cost Estimates, Schedule, Community Impact, O&M, and Adaptability

• Public Comment and Questions

• Wrap-Up

Presentation Outline

CSS Stakeholder Group Meeting #4 2

Purpose and Goals

Public Participation Goals


Increase stakeholder

awareness of the City’s

combined sewer

system and the Long Term

Control Plan Update

program.

Develop basic

understanding of the

Long Term Control Plan

Update recommended

strategies.

Awareness, consideration

and responsiveness on the

Long Term Control Plan.

Solicit feedback on the

combined sewer

control strategy

recommendations.

Resolution No. 2781

• Provide recommendations on how a primary combined sewer system control strategy can accomplish the City’s goals and permit requirements while minimizing impacts to the community

• Review and monitor the preparation of the Long Term Control Plan

• Permit and regulatory issues

• Engineering and analysis of infrastructure alternatives

• Implementation plan schedule and funding strategy

• Serve as a central information receiving/dissemination body related to the Long Term Control Plan

• Additional engagement opportunities following submission of the plan (working groups, implementation groups)

Stakeholder Group Charge


Alexandria’s Goals for the CSO Program


WATER QUALITYEnhance local infrastructure to improve the

water quality of Alexandria’s waterways.

INVESTMENT STEWARDSHIPBe good stewards of the rate payers’ investments in

both the short term and long term.

COMMUNITY BENEFITS AND CONSTRUCTION IMPACTSEngage the community, explore opportunities,

and be a good neighbor.

LEGISLATIVE MANDATEImplement the CSO Program to meet the legislative mandate.

Green Infrastructure Update

• City is refining the evaluation of Green Infrastructure (GI) and will report to the Group:

• Lessons learned from City’s experience and other CSO programs

• Opportunities and challenges in the combined sewer area

• Cost/benefit analysis of GI in the combined sewer area

• Potential GI strategies

• Present results at Stakeholder Meeting #5

Green Infrastructure Update


Summary of Options and Performance

City: ~15.2 square miles

CSO Area: ~540 acres, 6% of the city

Four permitted outfalls by DEQ:

•CSO-001 (Oronoco Bay)

•CSO-002 (Hunting Creek)

•CSO-003/004 (Hooffs Run)

Alexandria’s Combined

Sewer System

Combined Sewer

Service Area

Duke St.

CSO-003 & CSO-004

Pendleton St.

CSO-001

Royal St.

CSO-002

Hunting

Creek

Hooffs Run

Po

tom

ac R

ive

r

Alexandria Renew

Enterprises Water

Resources Recovery

Facility


Existing CSO System


CSO-002

Combined

Sewer

Area

CSO-001

AlexRenew

WRRF

Ho

off

s R

un

Hunting Creek

Po

tom

ac R

ive

r

Cameron Run

Oronoco

Bay

AlexRenew

Plant Outfall

CSO-003

CSO-004

(to be relocated)Final Effluent Outfall

Existing CSO

Existing Conveyance

Piping

Option ASeparate Tunnels with Wet Weather Treatment


AlexRenew

WRRF

CSO-002

Co

nve

yan

ce

Tu

nn

el

Wet Weather

Treatment

Sto

rage

Tu

nn

el

Treated Wet

Weather

Outfall and

Relocated CSO

004

CSO-003

CSO-004

(to be relocated)

CSO-001

Ho

off

s R

un

Hunting Creek

Po

tom

ac R

ive

r

Cameron Run

Oronoco

Bay

AlexRenew

Plant Outfall

New Conveyance

Piping

Final Effluent Outfall

Existing CSO

Existing Conveyance

Piping

Option BUnified Storage Tunnel


Ho

off

s R

un

Po

tom

ac R

ive

r

Cameron Run

AlexRenew

WRRF

CSO-002

2.2

MG

Sto

rage

Tu

nn

el

Storage and Conveyance Tunnel

Relocated CSO-004

CSO-003

CSO-004

(to be relocated)

AlexRenew

Plant Outfall

CSO-001

Hunting Creek

Oronoco

Bay

New Conveyance

Piping


Existing CSO

Existing Conveyance

Piping

Ho

off

s R

un

Po

tom

ac R

ive

r

Cameron Run

AlexRenew

WRRF

CSO-002

CSO-001

CSO-003

CSO-004

(to be relocated)C

on

ve

yan

ce

Tu

nn

el

Storage

Tank

Storage

Tank

AlexRenew

Plant Outfall

Wet Weather

Treatment

Hunting Creek

Oronoco

Bay

New Conveyance

Piping


Existing CSO

Existing Conveyance

Piping

Option CTunnel for 003/004 with Wet Weather Treatment and Tanks for 001/002


Treated Wet

Weather

Outfall and

Relocated CSO

004

0 10 20 30 40 50 60 70 80 90

CSO-001

CSO-002

CSO-003

CSO-004

Number of Overflow Events

Average Number of Overflows 2000-2016

Option A, 2Option B, 2Option C, 3

Existing, 78

Option A, 3Option B, 4

Option C, 3

Existing, 35

Option A, <1Option B, <1Option C, <1

Existing, 68

Option A, 1Option B, <1Option C, <1

Existing, 71

15CSS Stakeholder Group Meeting #4

* Preliminary performance

data, subject to change due

to further refinement

4-6 overflows/year

150.2 MG

18.7 MG

42.6 MG

20.8 MG

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0

Existing

Option A

Option B

Option C

CSO Volume (MG)

CSO-001 CSO-002 CSO-003 CSO-004

Average Volume of Overflows 2000-2016





Existing

Option A

Option B

Option C

68%

96%

91%

96%

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Percent Capture

Average Percent Capture 2000-2016





Existing

Option A

Option B

Option C

85%

Performance Conclusions


Option A

Separate Tunnels

Option B

Unified Storage

Tunnel

Option C

Tunnel for 003/004

and Tanks for

001/002

Meet Hunting Creek TMDL ✓ ✓ ✓

Reduce overflows to 4 per year (or less)

on average✓ ✓ ✓

Provide 85% capture ✓ ✓ ✓

Application of Evaluation Criteria

Evaluation Criteria Survey Score Description

Life Cycle Costs 4.07• Optimize the solution to minimize the impact to ratepayers

• Capital costs: planning, design, and construction

• Annual Operation and Maintenance Costs

Schedule 3.43• Risk of compliance with the mandated schedule

• Ability to secure necessary construction permits in a timely manner from local, state,

and federal agencies

Community Impact 3.93

• Minimize disruption to the community during construction.

• Minimize disruption to the community caused by regular Operation and Maintenance

activities.

• Maximize opportunities to incorporate community benefits.

O&M Complexity

and Reliability4.07

• Maximizes reliability of meeting VPDES permit

• Combined Sewer System Permit

• AlexRenew Wastewater Treatment Facility Permits

• Minimizes location and number of facilities to operate and maintain

Adaptability 3.93

• Ability to meet future capacity, environmental, or regulatory needs and navigate

climate change impacts

• Provides for opportunities for adaptive management and resiliency

• Integrate other planned City project needs if feasible

• Opportunities for complementary Green Infrastructure

Evaluation Criteria


Cost Estimates

Evolution of Program Costs


100%

80%

60%

40%

20%

0

-20%

-40%

-60%

-80%

-100%

100

50

3020

15

0

-50

-30-20

-15 -10

Pre

limin

ary

Desig

n

Pa

rtia

l D

esig

n

Com

ple

te F

ina

l

Desig

n (

Bid

)

Con

str

uctio

n

Com

ple

te

Cost Opinions

Lower Range of Probable Cost Upper Range of Probable Cost

PROGRAM STAGE

Ea

rly C

on

ce

pt (N

o S

ke

tch

es)

Con

ce

pt

(With S

ke

tch

es)

Capital Cost Estimates

23

WRRF Upgrades

CSO 003/4 Tunnel + Pumps

Wet Weather Facility

CSO 001/2 Tunnel

CSO 001/2 Tanks

TOTAL ESTIMATES

2.7

130

92

200

--

2.7

130

--

213

--

2.7

130

92

--

147

424 346 371

+50% TOTAL ESTIMATES 635 520 560

Cost $ Millions

(escalated to the midpoint of construction)

Option ASeparate Tunnels

Option BUnified Tunnels

Option CTunnel and Tanks


What are Life Cycle Costs?

CSO 003/4 Tunnel Example

24

Life Cycle Costs

Capital Costs (soft and

construction costs)

Operations Costs

Maintenance Costs

Capital Costs (present) $112M

O&M

Annual ($0.26M)

20 years @ 3% $4M

Net Present Worth $116M

Escalated to Midpoint (January 2023) $134M


Capital Cost Estimates

O&M Cost Estimates

TOTAL LIFE CYCLE ESTIMATES

+50% TOTAL LIFE CYCLE

ESTIMATES

Option ASeparate Tunnels

Option BUnified Tunnels

Option CTunnel and Tanks

Life Cycle Cost Estimates (20 years)


424

14

346

8

371

18

Cost $ Millions

438 354 389

657 531 583

25

Option B has the lowest estimated capital and life cycle costs

Cost Estimate Summary


0

50

100

150

200

250

300

350

400

450

Option A Option B Option C

$ M

illio

ns

Capital Life Cycle (20 years)

Evaluation Criteria Description

Life Cycle Costs• Optimize the solution to minimize the impact to ratepayers

• Capital costs: planning, design, and construction

• Annual Operation and Maintenance Costs

Evaluation Criteria


Schedule

2018 2019 2020 2021 2022 2023 2024 2025

1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

WRRF Upgrades

CSO 003/4 Tunnel


CSO 001/2 Tunnel

Option A


Design Procurement ConstructionPlanning, Permitting, and

Interagency Coordination

Option B


2018 2019 2020 2021 2022 2023 2024 2025

1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

WRRF Upgrades

CSO 003/4 Tunnel

CSO 001/2 Tunnel



2018 2019 2020 2021 2022 2023 2024 2025

1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

WRRF Upgrades

CSO 003/4 Tunnel


CSO 001/2 Tanks

Option C




• Federal

• State

Permitting Agency Coordination


Item Option A Option B Option C

Ability to meet

legislative milestone

• High risk, no schedule

flexibility for delays

• High risk, schedule


• Moderate risk, limited


Concurrent

construction projects

• High risk

• Complex coordination

at WRRF

• Single delay can affect

critical path

• Lowest risk, less

complex coordination

• Moderate risk

• Majority of projects

require coordination at

WRRF

• Single delay can affect

critical path

Construction and

regulatory

permitting

• Moderate risk since most

facilities are below-grade

• Moderate risk since

most facilities are

below-grade

• Highest risk due to temporary

and permanent footprint and

above-grade structures

Easements and

property acquisition

• Low risk due to small size

of temporary and

permanent surface

footprints

• Low risk due to small

size of temporary and

permanent surface

footprints

• High risk due to large size of

temporary and permanent

surface footprints

All options meet the legislative milestone

Key Schedule Risks

33


Schedule• Risk of compliance with the mandated schedule

• Ability to secure necessary construction permits in a timely manner from

local, state, and federal agencies

Evaluation Criteria


Community Impact

Shafts Tunnels TanksWet Weather

Treatment

Option A ✓ ✓ ✓

Option B ✓ ✓

Option C ✓ ✓ ✓ ✓

Different Facilities Have Different Impacts


N

AlexRenew’s Urban Footprint


How Do We Build Surface Facilities?

Excavation Support

Excavation

Permanent Construction

Restoration and Commissioning


Types of Excavation Support

Soldier Pile and Lagging

Slurry Wall

DewateringSecant Piles

Secant Pile Rig

Sheet Piling


Excavation


Shaft Excavation

Structure Excavation

Tank Excavation

Permanent Construction

Formwork

Rebar Installation

Concrete Pours and Finishing


How Do We Build a Tunnel?

100 to 120 feet deep

Ground Surface

Tunnel Shaft During and After


Tunnel Shaft Restoration


3 MG gallon storage capacity

Storage Tank During and After



Footprints During Construction

46

75% of a football field 150% of a football field

Tunnels Tanks

Example Renderings (Tunnels)


Example Rendering (Tanks)


SHORT-TERM Option A Option B Option C

Footprint (football field) 75% 75% 150%

Construction Duration (years) 2 2 3

Construction Work Hours 7AM – 6PM 7AM – 6PM 7AM – 6PM

Typical Hauling Rates

(trucks/hour)

2-10 2-10 5-20

Piles No No Yes

Impacts by Site – CSO 001 (Oronoco Bay)

49

LONG-TERM Option A Option B Option C

Above-grade Structure(s) Electrical cabinet Electrical cabinet Odor control,

electrical cabinet

Maintenance Frequency Monthly Monthly Weekly







(trucks/hour)

2-10 2-10 5-20

Piles No No Yes

Impacts by Site – CSO 002 (Hunting Creek)

50


Above-grade Structure(s) Electrical cabinet Electrical cabinet Odor control,

electrical cabinet

Maintenance Frequency Monthly Monthly Weekly







(trucks/hour)

2-10 2-10 2-10

Piles No No No

Impacts by Site – CSO’s 003/4 (Hooffs Run)

51


Above-grade Structure(s) Electrical cabinet Electrical cabinet Electrical cabinet

Maintenance Frequency Monthly Monthly Monthly




Construction Duration (years) 5 3 4.5

Construction Work Hours 24/7 (mining only) 24/7 (mining only) 24/7 (mining only)


(trucks/hour)

5-20 5-20 5-20

Piles Yes No Yes

Impacts by Site – AlexRenew

52


Above-grade Structure(s) Odor control,

operations building,

electrical, screens

Odor control, operations

building, electrical,

screens

Odor control,

operations

building,

electrical, screens

Maintenance Frequency Daily Daily Daily


• Soil Disturbances From excavation and grading activities

• Impacts to Groundwater From dewatering activities

• Noise and Vibrations Generated from construction activities

• Dust and Emissions Generated from construction activities

• Temporary Lane Closures Resulting in disruptions to traffic, parking,

and Restrictions public transportation

• Disruptions to Utilities i.e. water, gas, and electricity during

relocation activities

• Construction Activities May require the removal and proper disposal

of contaminated soil and groundwater

Other Potential Short-term ImpactsApplicable to all options


Option C has highest short and long-term impact

Community Impact Summary


Impact Option A Option B Option C

Short-term Minimal impact over

larger area

Minimal impact over

larger area

Highest impact in a

concentrated area

Long-term Low impact

• Most mechanical

equipment located

at WRRF

Low impact

• Most mechanical

equipment located

at WRRF

High impact within

community:

• Permanent above-

grade facilities

• Mechanical

facilities in

community

• Requires frequent

visits to tank

locations


Community Impact

• Minimize disruption to the community during construction.

• Minimize disruption to the community caused by regular Operation and

Maintenance activities.

• Maximize opportunities to incorporate community benefits.

Evaluation Criteria


O&M Complexity

Major Equipment


Pumps Screens Odor Control Flushing (Tanks only)

Electrical

Wet Weather Treatment Facility Use

0

5

10

15

20

25

30

35

40

45

50

20

00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

20

08

20

09

20

10

20

11

20

12

20

13

20

14

20

15

20

16

An

nu

al

Ho

urs

Year


Option B is the simplest to maintain due to centralized location of facilities and no wet weather treatment

O&M Complexity Summary



Location of

mechanical

facilities

• Low complexity since

mechanical equipment is

centralized at WRRF

• Least complexity since

mechanical equipment is

centralized at a single

location (at WRRF)

• Highest complexity due

to multiple locations of

mechanical equipment

Residuals

(solids and

floatables)

handling

• Low complexity due to

self-cleaning and

centrally located

residuals facilities

• Least complexity due to

self-cleaning and single

location for handling

residuals

• Highest complexity due

to routine access,

multiple residuals

handling locations, and

flushing system

New treatment

facilities

• Complex since limited

operation requires

equipment exercising

• Least complex, no wet

weather treatment facility

• Complex since limited

operation requires

equipment exercising


O&M Complexity

and Reliability

• Maximizes reliability of meeting VPDES permit

• Combined Sewer System Permit

• AlexRenew Wastewater Treatment Facility Permits

• Minimizes location and number of facilities to operate and maintain

Evaluation Criteria


Adaptability

Option B provides the most adaptability due to connectivity with WRRF

Adaptability Summary



Flexibility for future

changes (e.g.

regulatory, climate)

• Flexible

• Connects to WRRF

• Add pumping and

expand treatment

• Most flexible

• Unified system at

WRRF

• Add pumping and

treatment

• Least flexible

• Requires new

tankage or remote

treatment

• Connectivity to

WRRF limited by

interceptor


Adaptability

• Ability to meet future capacity, environmental, or regulatory needs and

navigate climate change impacts

• Provides for opportunities for adaptive management and resiliency

• Integrate other planned City project needs if feasible

• Opportunities for complementary Green Infrastructure

Evaluation Criteria


Next Steps

Long Term Control Plan Update Timeline

DEQ

Direction

CSS

Stakeholder

Meetings

Public

Meeting

30-Day

Public

Comment

Period

City

Council

Legislative

Session

Oct 2017 –

Mar 2018

March -

April

Apr 10,

2018

Early

April

AlexRenew

Board

Meeting

April 17,

2018

City

Council

Public

Hearing

April 28,

2018

Submit

LTCPU to

DEQ

Release

Draft

LTCPU

June 1,

2018


July 1,

2018

Late

March

CSS Stakeholder Meeting Schedule


Introduction/

Background

Evaluation

Criteria and

Shortlist of

Alternatives(all four outfalls)

Layouts of

Options and

Performance

Additional

Detail of

Options

Recommended

OptionWrap-Up

Discuss the

CSS/WW Plan

history, the 2016

LTCPU

submission, and

the new

legislation.

Introduce the

technologies

under

consideration

Introduce the

shortlist of

alternatives.

Review and

discuss the

evaluation criteria

and process

Review conceptual

layout of options.

Present

performance

Review options

with respect to

schedule, cost,

community

acceptance,

O&M, and

adaptability

Summarize scoring

and discuss

recommended

option. Review

potential rate

impacts. Green

Infrastructure

evaluation and

discussion. Discuss

Stakeholder

Recommendation

Process

Wrap-up and

present draft plan.

Stakeholder

Recommendation

discussion

Oct 12,

2017

Nov 20,

2017

Jan 10,

2018

Feb 22,

2018

March

2018

Feb 1,

2018

For more information, contact:

[email protected]

703.746.4065

[email protected]

703.746.4154

www.alexandriava.gov/CleanWaterways

Questions, Suggestions and Comments


mailto:[email protected]

mailto:[email protected]

http://www.alexandriava.gov/CleanWaterways

68

Thank You

city of alexandria and alexandria renew enterprises · presentation outline css stakeholder group...

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