Landsburg Mine Site, Ravensdale

Landsburg Mine Site, Ravensdale
Brief Overview of the Site and Status Update Since 2008
May 2011
Landsburg Mine Site
This Presentation will include:
• Site Background and History
• Update from the Last Meeting in 2008
• Hydrogeology of the Site
• Proposed Cleanup Action
• What’s Next?
Site Background and History
Site Location and Background
Landsburg Rd
North portal
Tahoma
Middle School
Clark Springs
Facility
South portal
Kent Kangley Rd
3‐D View of Mine Site
From May 1991 Site Hazard Assessment Report, Ecology and Environment, Inc. Coal
seam
Drums
Landsburg Mine Original Potentially Liable Parties (PLPs) • Browning-Ferris Industries/Allied Waste
• Burlington Northern and Santa Fe
Railroad Company
• PACCAR Inc.
• Plum Creek Timberland Company, L.P.
• Time Oil
• Palmer Coking Coal Company
• Burlington Environmental Inc.*
* subsidiary of Philip Services Corporation or PSC;
PSC bankruptcy settlement
Some Chemicals of Concern from Wastes Sampled in Subsidence Trench
Soil:
•Chromium, lead
•PCBs (polychlorinated biphenyls)
•Bis (2-ethylhexyl)phthalate
•Methylene Chloride
•TCE (trichloroethene)
•TPH (total petroleum hydrocarbons)
1960
1970
1980
1990
2000
ƒ1993 – EPA referred site to
state authority; MTCA Agreed
Order established
Early Timeline of Events
2010
ƒ1999, 2002, 2011
Draft Cleanup Action
Plans
Key Points about Landsburg Mine site
• Groundwater monitoring has never detected any
contamination which could be associated with the
wastes.
• Wastes were disposed in the northern trench area.
• No contaminants are migrating off of the waste area
in surface water or groundwater. Similarly, nothing
was detected in soils outside of the north trench area.
• We know the hydrogeology and contamination
sufficiently to select a remedy (Draft Cleanup Action
Plan or DCAP)
Update from the Last Meeting in 2008
Landsburg Mine Recent Events
• Continued groundwater monitoring twice a year.
• Summer 2008 – Construction of Infrastructure for
Contingent Groundwater Treatment System
• October 2008 to January 2009 – Hypothetical Travel
Time modeling using BIOSCREEN to derive long term
monitoring frequency
• Draft Cleanup Action Plan submitted to Ecology March
2011.
Contingent Treatment System Infrastructure
Treatment Infrastructure
Hydrogeology of the Site
Aerial view of site
Cross Section of Mines Groundwater Movement in Rogers Coal Mine
Proposed Cleanup Action
Cleanup Approach
• Conservative stance that wastes are still
there and remediation will proceed.
• Preferred cleanup approach:
• fill in trench and low permeability soil cap,
• surface water diversion,
• institutional controls on land & groundwater
use,
• contingent groundwater capture and
treatment should contamination be detected
at site wells
• groundwater monitoring in perpetuity
Proposed Cap Design
Hypothetical travel time modeling and Long term Monitoring Frequency
BIOSCREEN simulations were used to compute hypothetical travel times of contaminants in the possible event of a release within the mine
Combining simulated travel times with sentinel wells make the frequency of long‐term monitoring protective and practical
Long term groundwater monitoring frequency based on modeling
What’s next?
We are at the
Draft Cleanup
Action stage
What’s Next?
Finalize the Draft Cleanup Action Plan. We have
recently concluded:
• Long-term groundwater monitoring frequency –
based on BIOSCREEN modeling of the time it
takes a potential contaminant to travel a certain
distance.
• Some infrastructure for contingent groundwater
treatment at south portal based on City of Kent’s
request.
• Contingency Plan and Response Times – in revised
DCAP
Follow Timetable (last slide)
Landsburg Mine Site Remediation Timetable
•
Revised Cleanup Action Plan (CAP) to Ecology for re-evaluation
(presently undergoing Ecology review)
•
Draft CAP for public review
•
Public Comment on Draft CAP and Consent Decree
•
Engineer Design Report (2-6 months estimated by PLP Group);
•
Permit Requirements (2-9 months estimated by PLP Group)
•
Contractor Bid and Selection (2 months estimated by PLP Group)
•
Remedial Action Construction (two years)
•
Compliance Monitoring (in perpetuity)
Comments or Questions?