Combined Sewer System Permit and Long Term Control Plan ... · understanding of the Long Term Control ... COMMUNITY BENEFITS AND CONSTRUCTION IMPACTS ... Unified Storage Tunnel un

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Combined Sewer System Permit and Long Term

Control Plan Update

CSS Stakeholder Group

Meeting #3

January 10, 2018

City of Alexandria - Department of Transportation and Environmental Services

Alexandria Renew Enterprises

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PRESENTATION OUTLINE

Welcome

Purpose and Goals

Evaluation Criteria and Survey Results

CSO Program Options

Summary of CSO Performance

Green Infrastructure

Public Comment and Questions

Wrap-Up

3

Purpose and Goals

4

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.

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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(Resolution No. 2781)

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Alexandria’s Goals for the

CSO Program

WATER QUALITY Enhance 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 IMPACTS

Engage the community, explore opportunities, and be a good neighbor.

LEGISLATIVE MANDATEImplement the CSO Program to meet the legislative mandate.

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Evaluation Criteria

and Survey Results

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Evaluation

CriteriaDescription

Life Cycle Costs

• Optimize the solution to minimize the impact to rate payers.

• Capital costs: planning, design, and construction

• Annual Operation and Maintenance Costs

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.

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.

Schedule

• Risk of compliance with the mandated schedule.

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

and federal agencies.

Community

Acceptance

• 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

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LIFE CYCLE COSTS

O&M COMPLEXITY

ADAPTABILITY

SCHEDULE

COMMUNITY ACCEPTANCE

0 1 1 8 4

0 1 2 6 5

0 2 2 5 5

1 2 4 4 3

1 1 8 2 2

4.07

4.07

3.93

3.43

3.21

Evaluation Criteria

and Survey Results

☆ ☆☆ ☆☆☆

☆☆

☆☆

☆☆☆

☆☆

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Costs must be a consideration and this

project will cost a lot, particularly on an

accelerated basis.

Life Cycle Costs

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Adaptability is the most critical feature as we

need to build a system that will be durable

and serve our City needs through 2050 and

beyond as climate change will force us to

deal with more extreme precipitation events

and a rising Potomac River.

Adaptability

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The timetable is too ambitious.

But we should make a good faith effort

to attain it and hope the State will cut us

some slack later.

Schedule

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CSO Program Options

Existing CSO System

CSO-002

Combined

Sewer

Area

CSO-001

AlexRenew

WRRF

Ho

off

s R

un

Hunting Creek

Po

tom

ac

Riv

er

Cameron Run

Oronoco

Bay

AlexRenew

Plant Outfall

CSO-003

CSO-004

(to be relocated)

Final Effluent Outfall

Existing CSO

Existing

Conveyance Piping

2016 CSO Plan*Tunnels/Tanks Dewatered After the Storm

(2016 Plan for Outfalls 002/003/004)

AlexRenew

WRRF

CSO-002

CSO-001

CSO-003

CSO-004

(to be relocated)

Sto

rag

e T

un

ne

l

Storage

Tank

Storage

Tank

Relocated CSO-004

Ho

off

s R

un

Hunting Creek

Po

tom

ac

Riv

er

Cameron Run

Oronoco

Bay

AlexRenew

Plant Outfall

New Conveyance

Piping


Existing CSO

Existing

Conveyance Piping *Plan developed prior to the 2017 legislation. It included

green infrastructure and sewer separation over time.

Option ASeparate Tunnels withWet Weather Treatment

AlexRenew

WRRF

CSO-002

Co

nve

ya

nc

e T

un

ne

l

Wet Weather

Treatment

Sto

rag

e T

un

ne

l

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

Riv

er

Cameron Run

Oronoco

Bay

AlexRenew

Plant Outfall

New Conveyance

Piping


Existing CSO

Existing

Conveyance Piping

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Option ASeparate Tunnels with Wet Weather Treatment

Note: Potential

alignments shown for

illustrative purposes.

Only one alignment will

be selected for potential

construction.

CSO 001

CSO 002

CSO 004current location

CSO 003

CSO 004Relocation

Po

tom

ac R

iver

Option BUnified Storage Tunnel

Ho

off

s R

un

Po

tom

ac

Riv

er

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

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Note: Potential

alignments shown for


Only one alignment will


construction.

CSO 001

CSO 002

CSO 004current location

CSO 003

CSO 004Relocation

Po

tom

ac R

iver

Ho

off

s R

un

Po

tom

ac

Riv

er

Cameron Run

AlexRenew

WRRF

CSO-002

CSO-001

CSO-003

CSO-004

(to be relocated)

Co

nve

ya

nc

e T

un

ne

l

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

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

Note: Potential tunnel

alignments and tank

sites shown for


Only one tunnel

alignment and one tank

site at each location will


construction.

Oronoco

Bay

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Summary of CSO Performance

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Reducing CSOs will improve the water quality of Alexandria’s

waterways

CSOs contribute a relatively small percentage of the bacteria load

in the receiving waters

All options meet the very stringent regulatory requirements, as

such all options will provide relatively equal water quality benefits

Water quality benefits are maximized; CSO reductions beyond the

regulatory requirements will not provide any discernable water

quality benefits

Key Points

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Oronoco Bay (001)

Hooffs Run and

Hunting Creek (002/3/4)

Potomac River

Three Water

Bodies

ADD MAP

Oronoco Bay

Hunting Creek

Embayment

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EPA CSO Control Policy (all outfalls)“A program that meets any of the criteria listed below would be presumed to provide an adequate level of control to meet the water quality-based requirements of the CWA [Clean Water Act]…

1. No more than an average of four overflow events per year, provided that the permitting authority may allow up to two additional overflow events per year

2. The elimination or the capture for treatment of no less than 85% by volume of the combined sewage

3. The elimination or removal of no less than the mass of pollutants…for the volumes that would be eliminated or captured for treatment under paragraph [2] above

The presumption approach is based on the typical year. Following a statistical analysis of 40 years of rainfall data, 1984 was determined to be the typical year.

Presumption Approach

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Hunting Creek Bacteria TMDL (Outfall 002, 003, & 004 only)

99% reduction from Outfalls 003 and 004 (Hooffs Run)

80% reduction from Outfall 002 (Hunting Creek)

The Hunting Creek TMDL is based on the years

2004 – 2005.

Hunting Creek TMDL

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Hunting Creek

Bacteria Loads

Note: From Hunting Creek TMDL (2010)

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Potomac River

Bacteria Loads

The CSO-001 load is only a portion of the Virginia load

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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

* Preliminary performance

data, subject to change due

to further refinement

Option A: Separate Tunnels w/ Wet

Weather Treatment for 003/004

Option B: Unified Storage Tunnel

Option C: Tunnel for 003/004 w/ Wet

Weather Treatment and Tanks for 001/002

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Average Volume of Overflows

2000-2016

151 MG

17 MG

39 MG

22 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




Option A: Separate Tunnels w/ Wet Weather

Treatment for 003/004


Option C: Tunnel for 003/004 w/ Wet Weather

Treatment and Tanks for 001/002

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Average Percent Capture

2000-2016

Existing, 68%

Option A, 97%

Option B, 92%

Option C, 96%

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

CSS

% C

aptu

re

Percent Capture




Option A: Separate Tunnels w/ Wet

Weather Treatment for 003/004


Option C: Tunnel for 003/004 w/ Wet

Weather Treatment and Tanks for 001/002

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Performance: All CSOs




Existing

Option ASeparate Tunnels w/

Wet Weather

Treatment

Option BUnified Storage

Tunnel

Option CTunnel for 003/004

w/ Wet Weather

Treatment and

Tanks for 001/002

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84

No. Overflows per Year 38 – 70 0-0 0-1 0-1

Overflow Volume per Year

(million gallons)97.1 0.0 3.5 0.4

% Capture 77% 100% 99% 100%

20

00

-20

16 No. Overflows per Year 35 – 79 0-3 1-4 1-3


(million gallons)150.2 18.6 42.6 20.8

% Capture 68% 96% 91% 95%

Bacterial TMDL Met (2004-2005)? --

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Performance: CSO 001

Existing


Wet Weather

Treatment


Tunnel


w/ Wet Weather

Treatment and

Tanks for 001/002

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84

No. Overflows per Year 38 0 1 1



% Capture 81% 100% 98% 100%

20

00

-20

16 No. Overflows per Year 35 3 4 3



% Capture 74% 99% 78% 95%

Bacterial TMDL Met (2004-2005)? -- N/A N/A N/A




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Existing


Wet Weather

Treatment


Tunnel


w/ Wet Weather

Treatment and

Tanks for 001/002

19

84




% Capture 81% 100% 100% 100%

20

00

-20

16 No. Overflows per Year 78 2 2 3



% Capture 71% 99% 99% 95%





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Existing


Wet Weather

Treatment


Tunnel


w/ Wet Weather

Treatment and

Tanks for 001/002

19

84




% Capture 42% 100% 100% 100%

20

00

-20

16 No. Overflows per Year 68 <1 <1 <1



% Capture 40% 99% 99% 99%





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Existing


Wet Weather

Treatment


Tunnel


w/ Wet Weather

Treatment and

Tanks for 001/002

19

84




% Capture 85% 100% 100% 100%

20

00

-20

16 No. Overflows per Year 71 1 <1 1



% Capture 82% 96% 98% 96%





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Why Not Zero?

Section II.C.5 of the EPA CSO Control Policy recommends

performing this type of knee of the curve analysis to help

determine CSO controls.

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30 35 40 45 50 55

Ove

rflo

ws P

er

Ye

ar

Tunnel Diameter (ft)

Diameter vs Overflows Per Year (2000-2016)

10’ Diameter<=4 overflows

52’ Diameter≈0 overflows

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Performance Conclusions

Option ASeparate Tunnels w/ Wet

Weather Treatment


Option CTunnel for 003/004 w/ Wet

Weather Treatment and

Tanks for 001/002

Meet Hunting Creek TMDL

Reduce overflows to 4 per year

(or less) on average

Provide 85% capture

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Water Quality Benefit is assessed by how much improvement

can be obtained in meeting Water Quality Standards

All options sized to meet the regulatory requirements

All options provide substantial Water Quality Improvements

All options remove bacteria load beyond the level that Water

Quality Improvements can be discerned

After CSO controls are implemented other sources of bacteria

(stormwater, wildlife, SSO/septic, etc.) will dictate the quality of the

receiving waters.

Water Quality

Conclusions

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Green Infrastructure Recap

and Discussion

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GI incorporated as a complementary strategy

$5 - $7.5 M in City-led GI projects (2018-2035)

Evaluate incentive programs for private developers and

property owners

Evaluate increasing number of trees and tree canopy in the

CSS area

Adaptive Management Tool:

Evaluate, assess cost and effectiveness, adjust

Promote resiliency

Address impacts of climate change

Green Infrastructure

2016 CSO Plan

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GI will continue to be a complementary strategy for the LTCPU

$3.2 M in 10 year CIP (2018-2027) for GI

GI will be incorporated into the Chesapeake Bay TMDL Action

Plan

Public Engagement Process (2018-2019)

City Council Public Hearing and Approval in 2019

The City will perform additional studies to:

Incorporate results from early projects

Implement for adaptability and climate change

GI is being implemented Citywide which includes the

combined sewer system area

City’s Commitment to Green

Infrastructure

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Next Steps

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CSS Stakeholder

Meeting Schedule

Introduction /

Background

Evaluation

Criteria and

Shortlist of

Alternatives

(all four outfalls)

Layouts of

Options and

Performance

Additional

Detail of

Options

Preferred

Option Wrap-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, present

selected option,

and provide

further detail on

schedule, cost,

community

acceptance,

O&M, and

adaptability.

Wrap and

present draft

plan.

OCTOBER 12,

2017

NOVEMBER 20,

2017

JANUARY 10,

2018

LATE FEB

2018

MARCH

2018

FEBRUARY 1,

2018

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For more information, contact:

[email protected]

703.746.4065

[email protected]

703.746.4154

www.alexandriava.gov/CleanWaterways

Questions/Suggestions/Comments

mailto:[email protected]

mailto:[email protected]

http://www.alexandriava.gov/CleanWaterways

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Thank You

Documents

Combined Sewer System Permit and Long Term Control Plan ... · understanding of the Long Term Control ... COMMUNITY BENEFITS AND CONSTRUCTION IMPACTS ... Unified Storage Tunnel un