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DC CLEAN RIVERS PROJECT

Northeast Boundary Tunnel

Briefing on:

Briefing for:

Trinidad Civic Association

April 28, 2015

District of Columbia Water and Sewer Authority George S. Hawkins, General Manager

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Long Term Control Plan (LTCP) to: Relieve flooding in the Northeast

Boundary Area

Control combined sewer overflows to: Potomac River

Anacostia River

Rock Creek

Meet nutrient discharge limits of

Chesapeake Bay Program

Schedule: 2005-2025

Implemented under a Federal Consent

Decree among: United States Environmental

Protection Agency (US EPA)

United States Department of Justice

(US DOJ)

District of Columbia

DC Water

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Background

Project Snapshot

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Lady Bird Mining Location

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Background

History of Flooding

Sewer system constructed in the late 1800’s when the

developed area of the District terminated at Florida Avenue

Rural areas converted to impervious neighborhoods resulted

in increased stormwater runoff

Existing capacity limitations within the sewershed were

exacerbated by development

Low-lying areas have become chronic flooding areas due to

the surcharging of sewers during storm events

No. Known Chronic Flood Areas

1 West Virginia Ave & Mt Olivet Rd

2 Rhode Island Ave Metro

3 6th & R Sts NW

4 Bloomingdale & LeDroit Park

5 Harvard & Sherman Ave NW

6 1st and P Sts NW

7 NEB Trunk Sewer

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Summer 2012 Storm Events

Peak Intensity and Return Interval

Date Duration Rainfall

(inches)

NOAA Point

Precipitation

Frequency (Nearly)

7/10/2012 1-hour 1.96 10-year storm

7/18/2012 30-minute 1.35 5-year storm

7/19/2012 15-min 0.94 5-year storm

9/2/2012 2-hour 2.78 10-year storm

4 Storm Intensity Map Courtesy of:

Washington Post

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Summer 2012 Storm Events: Surface Flooding

Rhode Island Metro

1st St NW

Flagler St NW

Rhode Island & T St NW

Rhode Island Between 1st & 2nd St

Rhode Island & T St NW

Rhode Island & 1st St NW

5 1st & V St NW

Photo courtesy of: Greg Roberts

Photo courtesy of

huffintonpost.com

Photo courtesy of myfox.com

Photo courtesy of myfox.com

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Photo source unknown

Photo source unknown

Photo source unknown

Photo source unknown

Photo source unknown

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Mayor’s Task Force

Overview

4 storms caused major

flooding: July 10, 18, 19

and Sept 2, 2012

Mayor formed Task

Force in Aug 2012

Task Force report

delivered end of Dec

2012

Over 25 Recommendations:

Engineering Measures • McMillan Stormwater Storage

• First Street Tunnel

• Northeast Boundary Tunnel

(NEBT)

Regulatory Code Changes Operations &

Maintenance Public

Outreach

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Mayor’s Task Force

Recommended Plan

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NORTHEAST BOUNDARY TUNNEL PROJECT A large, deep sewer tunnel that will increase the capacity of

the sewer system to current design standards and control combined sewer overflow discharges to the Anacostia River

Completion in 2022

MCMILLAN STORMWATER STORAGE PROJECT Repurpose McMillan Sand Filtration cells as stormwater

storage In-line storage in a sewer that runs along First Street NW 3.6 million gallons. Completed

IRVING STREET GREEN INFRASTRUCTURE PROJECT Construction of bioretention facilities along Irving Street NW 0.4 million gallons. Completed

FIRST STREET TUNNEL PROJECT Construction of a new tunnel under First Street NW Construction of diversion facilities to divert flows to tunnel 8 million gallons, Completion in Spring 2016

2. MEDIUM-TERM

3. LONG-TERM

Construction of green infrastructure projects Installation of storm drains and a five-foot-wide storm sewer Backwater valve and rain barrel program

1. SHORT-TERM (NOT ILLUSTRATED)

N

9

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Significantly mitigate the frequency, magnitude

and duration of sewer flooding and basement

backups in the Northeast Boundary drainage

area

Control combined sewer overflow (CSO)

discharges to the Anacostia River, significantly

improving water quality

Minimize the nuisance and economic costs

associated with flooding

Reduce risks to human health

Greatly reduce the discharge of untreated

wastewater into the District’s receiving

waterbodies

Prevent deterioration of historic resources from

water damage caused by flooding

Mayor’s Task Force

Benefits

CSO Reduction Project Timeline

CSO Overflow Volume

to Anacostia River

(mg/yr)

% Reduction from

Baseline

1996: Baseline: Without Inflatable Dams or Pumping Station Rehab 2,142

2008: After Inflatable Dams and Pumping Station Rehab 1,282 40%

2018: Blue Plains and Anacostia River Tunnels 407 81%

2022: Northeast Boundary Tunnel* 54 98%

CSO Reduction

* 2025 Consent Decree Deadline; Project accelerated due to Mayor’s Task Force recommendations. 8

Flood Relief

SIG

NIF

ICA

NT

C

SO

RE

DU

CT

ION

Capacity provided by Long-Term Improvements (NEBT)

Approx. capacity of existing system

Capacity provided by Medium-Term Improvements

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Mayor’s Task Force

Summary of Progress

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Step Program Responsibility Schedule per Task Force Status

SH

OR

T-T

ER

M

Backwater Valve Program DC Water

Implement until Northeast Boundary Tunnel in-service (2022)

• 60 installations since inception

Rain Barrel Program DDOE Implement immediately (2013) • Completed in February 2014 –

128+ rain barrels installed

Stormwater/ Green Infrastructure

DDOT Implement within 12 months (2013)

• Construction completed – operational in 2013

ME

DIU

M-T

ER

M

Irving Street Green Infrastructure

DC Water Place in service by 2014 • Construction completed –

operational in 2014

McMillan Stormwater Storage

DC Water Place in service by Spring 2014 • Construction completed –

operational in Spring 2014

First Street Tunnel DC Water Place in service by spring 2016 • Construction started in October

2014 • See next slide for detail

LO

NG

-T

ER

M

Northeast Boundary Tunnel

DC Water Place in service by 2022

• Environmental Assessment completed February 2014

• Design underway • Public outreach ongoing

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Background

What is a Diversion Facility?

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Northeast Boundary Tunnel

Alignment and Chronic Flood Areas

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Significant Work

along Rhode

Island Avenue

Corridor

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Northeast Boundary Tunnel

Mitigation Measures

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Public outreach during

planning and design

• Contract milestones • Advanced utility relocations • Collaboration process –

selected best value

• Pre-post-construction surveys • 24/7 hotline • Security service • Vector control • Street cleanings • Noise attenuation • Noise & vibration specialist

Incorporate mitigation measures into design and

construction

MINIMIZE DURATION MINIMIZE IMPACTS

• Traffic Study (Transit, Pedestrian and Bicycle included) •Off-peak hauling • Compact construction sites •Maintain access/services • Extensive coordination with

District agencies

MAINTAIN QUALITY OF LIFE

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Northeast Boundary Tunnel

Utility Relocation

Utility Relocation

Gas and electric, communications, water and sewer utilities in vicinity

of the near surface structures (NSS) along the Northeast Boundary

Tunnel alignment will be relocated

Informational sheets with map will be hand delivered to residents

within the affected area

Work will begin in June 2016 and extend through April 2017. Work

will be concentrated at individual sites for the duration required per

site

Schedule and duration at sites is currently being developed

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14 14 14

Northeast Boundary Tunnel

Mt. Olivet Road Diversion and Ventilation Control Facility

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Next Steps

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Place in Operation – Spring 2016

Place in Operation – 2022

CSO Relief

Flood Relief

(Mayor’s Task Force)

Continue to work collaboratively with the District to meet project goals

Progress design

Continue public outreach throughout the project area

Relocate utilities in advance of construction: 2016

Construction: April 2017 – 2022