former potrero power plant site remediation welcome
TRANSCRIPT
Former Potrero Power Plant Site Remediation
WELCOMEPG&E Community Open House
Offshore Sediment Area Investigation Findings
November 20, 2013
Former Potrero Power Plant Site Remediation
Former Potrero Power Plant Site
Photo taken: March 2012.
Former Potrero Power Plant Site Remediation
GA
S
RESIDENCES
STREET LAMPS
BUSINESSES
MANUFACTURINGPROCESS
GAS HOLDER
COAL OR OIL
What is a Manufactured Gas Plant (MGP)?
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
Timeline-Sediment Remediation
1990
20002010
1995
20052015
202019
9620
0619
9120
0120
1120
1619
9720
0719
9220
0220
1220
1719
9820
0819
9320
0320
1320
1819
9920
0919
9420
0420
1420
19
1990–PresentEnvironmental Investigations. Site Wide Soil and Groundwater Sampling.
2014–2015Offshore Sediment Remedial Action Plan Process
2013–2014Offshore Sediment Feasibility Study Process (including public participation process)
2015–2016Offshore Sediment Cleanup Design
2014–2016Offshore Sediment Permitting
2009–2013Offshore Sediment Remedial Investigations and Survey
2016Off-shore Sediment Construction and Field Work
Former Potrero Power Plant Site Remediation
1870
1920
1970
1880
1930
1980
1890
1940
1990
1900
1950
200019
1019
602015
2010
Timeline-Operations
1999PG&E sells Potrero Power Plant to Southern Company.
1870s–1930sAn MGP operated on Potrero Property.
1910s–1970sPG&E operates Potrero Power Plant Station A (Units 1 and 2).
1965–1999PG&E operates Potrero Power Plant Unit 3.
PG&E
March 2011Potrero Power Plant shuts down.
NRG
1999–2013Southern Co. (subsequently, Mirant Corp., then GenOn and now NRG Potrero, LLC) owns Potrero Power Plant Unit 3.
2007–2010Trans Bay Cable Project completed.
Former Potrero Power Plant Site Remediation
Project Site
Approximate boundaries shown. Map not to scale.
23RD ST.
22ND ST.
ILLINO
IS ST.
3RD
ST.
TEN
NE
SSEE
ST.
OFFSHORE INVESTIGATION AREA
280
PG&E-Owned Properties NRG Potrero, LLC Owned Properties Port of San Francisco Property Impacted by Historical MGP Activities
N
Port Property
Station A
Tank Farm
Switchyard/Construction Yard Northeast
Area
Hoe Down Yard
Former Power Generation Facility
Approx. 500 ft.
Former Potrero Power Plant Site Remediation
Offshore Sediment Remedial Investigation Report
• Summarizes findings of four phases of investigations
• Characterizes impacts of former MGP, power plant and other industrial activities
• Identifies areas that may require remediation
• Investigations included the following:−− 88 surface sediment samples
−− 64 sediment cores
−− 96 profiles using advanced TarGOST technology
−− 50 sediment profile imaging stations
−− 10 benthic community evaluation stations
−− 27 bioaccumulation stations
−− 9 stations for sedimentation rate evaluation
−− Survey of depth to sediment surface
Extensive sampling was conducted during four phases of sediment investigations.
Former Potrero Power Plant Site Remediation
A Typical Healthy Marine Ecosystem
• Benthic organisms include a variety of invertebrates that live on or in underwater sediments
• They serve as an important food source for bottom-feeding fish and some birds
• The presence of an abundant and diverse benthic community is one sign of a healthy marine ecosystem
For illustrative purposes only. Image not to scale.
Water
Healthy Benthic Community
Oxidized Sediment
Former Potrero Power Plant Site Remediation
Offshore Sediment Remedial Investigation Report Findings
• Majority of impacts located close to shoreline and in some isolated, deep sediment areas further from shore (more than 15 feet below sediment surface)
• No current human health risk
• No toxicity to sediment organisms; bioaccumulation occurring in some areas
• Healthy, abundant and diverse benthic community currently exists
In the absence of chemical or physical disturbance, benthic organisms burrow into soft sediment, feeding on bacteria and oxidizing the sediment, providing a better habitat for a diversity of organisms, such as the sea pens so abundant in the Potrero offshore sediments.
For illustrative purposes. Images not to scale.
Healthier Benthic CommunityLess-Healthy Benthic Community Abundant Sea Pens in Offshore Sediments
Oxidized Sediment
Oxidized Sediment
Un-oxidized Sediment
Un-oxidized Sediment
Water Water
Former Potrero Power Plant Site Remediation
Remedial Investigation Report Recommendations
Port Property
Station A
Tank FarmNortheastArea
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
Approximate boundaries shown. Map not to scale.
Former Power Generation Facility
N
• Remove impacts in the shoreline and nearshore area
• Reduce potential for bioaccumulation in benthic organisms where it is above ambient bioaccumulation levels
• Minimize disturbance to the remainder of the benthic community
• These recommendations are supported by state and federal regulatory oversight agencies
OFFSHORE INVESTIGATION AREA
280