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Former Potrero Power Plant Site Remediation

WELCOME

PG&E Community Open House

Former Potrero Power Plant Site Remediation

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Former Potrero Power Plant Site

Photo taken: March 2012.

Former Potrero Power Plant Site Remediation

Project Site

Approximate boundaries shown. Map not to scale.

PG&E-Owned Properties NRG Potrero, LLC Owned Properties Port of San Francisco Property Impacted by Historical MGP Activities

23RD ST. 22ND ST. I L L I N O I S S T . 3 R D S T . T E N N E S S E E S T .

OFFSHORE SEDIMENT AREA

280

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Port Property Station A (NRG Owned) Station A (PG&E Owned) Tank Farm Switchyard/ Construction Yard Northeast Area Hoe Down Yard Former Power Generation Facility

Former Potrero Power Plant Site Remediation

What is a Manufactured Gas Plant (MGP)?

GAS RESIDENCES STREET LAMPS BUSINESSES

MANUFACTURING PROCESS

GAS HOLDER

COAL OR OIL

Former Potrero Power Plant Site Remediation

Goals

Fulfill our commitment to address impacts from historic MGP and power plant operations. Protect human health and the environment. Work collaboratively with stakeholders and the community. Protect the safety of the community and site workers. Allow for the productive re-use of the site.

Former Potrero Power Plant Site Remediation

1870 1920 1970 1880 1930 1980 1890 1940 1990 1900 1950 2000 1910 1960 2015 2010

Timeline-Operations

1999

PG&E sells Potrero Power Plant to Southern Company.

1870s–1930s

An MGP operated on Potrero Property.

1910s–1999

PG&E operates Potrero Power Plant.

March 2011

Potrero Power Plant shuts down.

1999–Present

Southern Co. (subsequently, Mirant Corp., then GenOn and now NRG Potrero, LLC) owns Potrero Power Plant.

2007–2010

Trans Bay Cable Project completed.

PG&E NRG

Former Potrero Power Plant Site Remediation

2 1 2 5 2 1 5 2 2

2 6 2 1 1 2 1 6 2 7 2 1 2 2 1 7 2 8 2 1 3 2 1 8 2 9 2 1 4 2 1 9

1990–2013

Environmental Investigations. Site Wide Soil and Groundwater Sampling.

2014–2015

Offshore Sediment Feasibility Study Process (including public participation)

2015–2016

Offshore Sediment Remedial Action Plan Process (including public participation)

2016–2017

Offshore Sediment Cleanup Design

2016–2017

Offshore Sediment Permitting

2009–2013

Offshore Sediment Remedial Investigations and Survey

2018

Offshore Sediment Construction and Field Work

Timeline-Sediment Remediation

Former Potrero Power Plant Site Remediation

Offshore Sediment Draft Feasibility Study

• Draft Feasibility Study (FS)

evaluates cleanup options for impacted sediments and identifjes a preferred approach

• Draft FS submitted to SF Regional

Water Quality Control Board (Water Board) for review and public comment

• Public comment period scheduled

for May/June 2015 (pending Water Board approval)

• Public outreach
• Public Comment Period
• Fact Sheet

For illustrative purposes only. Approximate boundaries shown. Image not to scale.

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Port Property Station A Tank Farm Northeast Area

OFFSHORE SEDIMENT AREA

NRG Potrero, LLC Owned Properties Port of San Francisco Property Impacted by Historical MGP Activities

Former Power Generation Facility

Former Potrero Power Plant Site Remediation

Port Property Station A Tank Farm Northeast Area

NRG Potrero, LLC Owned Properties Port of San Francisco Property Impacted by Historical MGP Activities Areas of Benthic Organism Bioaccumulation Above Ambient Conditions Shoreline and Nearshore Areas Where Impacts Will be Addressed

Former Power Generation Facility

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OFFSHORE SEDIMENT AREA

Preferred Option:

Sediment Removal, Capping, In-Place Treatment and Natural Recovery Targeted cleanup methods will address varying conditions throughout the Offshore Sediment Area:

• Removal of impacted sediments

and capping with natural materials (Nearshore Area)

• In-place treatment with activated carbon

(Northern Transition Area)

• Monitored natural recovery

(Southern Transition Area)

• Estimated time to complete:
• Design, permitting and contracting:

Approximately 2 years

• Construction: Approximately 6-8

months

Former Potrero Power Plant Site Remediation

A Typical Healthy Marine Ecosystem

For illustrative purposes only. Image not to scale.

Water Healthy Benthic Community Oxidized Sediment

• Benthic organisms include a variety of invertebrates that live on or in

underwater sediments

• They serve as an important food source for bottom-feeding fjsh and some birds
• The presence of an abundant and diverse benthic community is one sign of

a healthy marine ecosystem

Former Potrero Power Plant Site Remediation

Benefjts of Preferred Option

• Long-term effectiveness and permanence
• Minimizes impact to healthy, diverse marine ecosystem in Offshore Sediment Area
• Addresses surface sediments with elevated concentrations of impacts along

the shoreline

Crews collect samples from Offshore Sediment Area during 2012 investigation effort. Preferred cleanup option addresses impacted sediments in the Offshore Area.