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Partial response to FOIA request for documents re Army Corps of Engineers & NRC analyses of potential for debris dam blocking natural outlet of Spirit Lake to rupture.Apps A & B documents available in PDR.

Accession Number: ML19264D658

Date Released: Friday, October 25, 2024

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• ML20133F110 - Partial response to FOIA request for documents re Army Corps of Engineers & NRC analyses of potential for debris dam blocking natural outlet of Spirit Lake to rupture.Apps A & B documents available in PDR. (7 page(s), 6/18/1985)
• ML20132C141 - Forwards hydraulic engineering rept & recommendations re postulated breakout of Spirit Lake & impacts on plant. Recommendations based on preliminary info & subj to change. (12 page(s), 5/11/1984)
• ML20132B636 - Forwards util 830902 response to NRC questions on util 830701 submittal re potential mudflows from assumed failure of Spirit Lake blockage.Util consultant final rept also encl.W/o rept. (2 page(s), 9/15/1983)
• ML20132B773 - Forwards Geologic Hazards Bulletins 84-5,84-7 & 84-8 & internal review of "Comprehensive Plan for Responding to Long-Term Threat Created by Eruption of Mount St Helens,WA." Documents relevant to recent increased volcanic activity. (23 page(s), 2/7/1984)
• ML20132B753 - Advises of USGS issuance of volcano alert indicating imminent eruption of Mount St Helens.Prediction based upon marked increase in level of background seismicity w/rapid dome growth.Nearby facilities would not be affected. (11 page(s), 2/7/1984)
• ML20133F700 - Forwards USGS rept entitled, "Impact of Outburst of Spirit Lake on Columbia River." Rept substantiates info provided earlier. (77 page(s), 10/4/1984)
• ML20132B600 - Forwards memo,prepared for signature,authorizing USGS to commence Phase II of "Analysis of Potential Flood Levels at Trojan Nuclear Power Plant," due to Spirit Lake debris dam failure.Statement of work encl. (9 page(s), 7/12/1983)
• ML20132B785 - Discusses Hydrologic Engineering Section monitoring of Mount St Helens possible eruption & determination of affect of release from Spirit Lake on plant operation. (4 page(s), 2/24/1984)
• ML20132B645 - Requests technical assistance to review encl "Evaluation of Design Hazards of Airborne Ash & Pyroclastic Flow for Trojan Nuclear Plant." (2 page(s), 1/19/1981)
• ML20132C780 - Forwards SER re effects of breakout of Spirit Lake on facility.Conclusion that breakout will not affect safety based on unpublished USGS study rept & subj to change. Permanent outlet tunnel under const will resolve concern. (9 page(s), 3/6/1985)
• ML20133F674 - "Preliminary Estimate of Possible Flood Evaluation in Columbia River at Trojan Nuclear Power Plant Due to Failure of Debris Dam Blocking Spirit Lake,WA." (16 page(s), 12/31/1984)
• ML20133F510 - "Mount St Helens Eruption,Challenge to Restore & Protect." (91 page(s), 10/31/1981)
• ML20132B237 - Forwards DOI 800529 ltr re increased flood potential in Longview & Kelso areas from Mount St Helens eruption.Since Cowlitz is downstream from facility notice has no impact on facility flooding. (17 page(s), 6/3/1980)
• ML20133F531 - Discusses Meteorology & Effluent Treatment Branch review re USGS/FEMA rept, "Water Resources Investigation Rept 82-4125." (1 page(s), 3/17/1983)
• ML20132B648 - "Evaluation of Design Hazards of Airborne Ash & Pyroclastic Flow for Trojan Power Plant Site." (15 page(s), 10/5/1980)
• ML19264D657 - Trip rept of 830317 site visit re post-eruption condition of streams & rivers draining Mount St Helens & re effect of failure of Spirit Lake blockage on facility. (7 page(s), 4/18/1983)
• ML20133F596 - Certifies that funds authorized for Interagency Agreement NRC-03-83-109 entitled, "Analysis of Potential Flood Levels at Trojan Nuclear Power Plant." Estimates completion of Phase 1 2 wks after initiation of work. (5 page(s), 6/1/1983)
• ML20133F656 - Forwards summary of Corp of Engineers actions to solve Spirit Lake problem. (14 page(s), 12/5/1983)
• ML20133F730 - Forwards comparison of two analyses of potential mudflow flood resulting from failure of debris dam in front of Spirit Lake near Mount St Helens.USGS results higher than expected.Simons & Li values too low.W/o encl. (1 page(s), 4/5/1984)
• ML20133F569 - Forwards request for procurement action,Parts 1 & 2,re analysis of potential flood levels for action.W/o encl. (1 page(s), 5/27/1983)
• ML20132C361 - Requests issuance of final safety evaluation re refined sediment transport routing model to study impacts of Spirit Lake breakout on Columbia River.FEMA 840331 ltr to util summarizing USGS study encl. (10 page(s), 8/8/1984)
• ML20133F504 - "Mudflow Hazards Along Toutle & Cowlitz Rivers From Hypothetical Failure of Spirit Lake Blockage." (15 page(s), 3/31/1983)
• ML20133F847 - Forwards brief summary of preliminary findings on impact of mudflow from Spirit Lake near Mount St Helens.Findings provisional & subj to review & approval of Director of USGS. (3 page(s), 6/20/1983)
• ML20133F542 - Notification of 830408 meeting to view slides of Spirit Lake & area,to learn observations of visited areas & to discuss future NRC action. (1 page(s), 4/1/1983)
• ML20132B567 - Forwards questions for transmittal to licensee re postulated breakout of Spirit Lake & effects on facility. (13 page(s), 5/4/1983)
• ML20133F773 - "Preliminary Estimate of Possible Flood Elevations in Columbia River at Trojan Nuclear Power Plant Due to Large Mudflow in Cowlitz River." (25 page(s), 6/30/1983)
• ML20132B606 - Forwards request for addl info re util 830701 rept, "Potential Mudflow From Hypothetical Failure of Spirit Lake Blockage." (3 page(s), 7/19/1983)
• ML20132B532 - Requests continuing updated info re ongoing/proposed studies of Mount St Helen volcanic activity & effect on nearby nuclear facilities.First monthly ltr rept expected by 830401. (6 page(s), 3/2/1983)
• ML20132C836 - Forwards revised SER input re effects of breakout of Spirit Lake on plant.Conclusions in previous SER based on unpublished USGS rept & did not mention independent study performed by applicant. (8 page(s), 3/28/1985)
• ML20133F743 - Forwards transparency matls presented at 840223 meeting re facility. (17 page(s), 3/12/1984)
• ML20133F786 - Summarizes 830511 meeting at Corps of Engineers ofc in Portland,OR re determination of flood elevations at facility resulting from breach of debris barrier at Spirit Lake,WA. Related info encl. (14 page(s), 5/12/1983)
• ML20132B792 - Forwards comments re "Flood & Sedimentation Hazards in Toutle & Cowlitz River Sys as Result of Mt St Helens Eruption,1980." Rept does not raise issues which would question safety of facility. (4 page(s), 2/6/1981)