ML20247B826

Summary of 890504 Grand Junction Project Meeting W/Doe & DOE Contractors Re Results of Addl Characterization of Cheney Reservoir Disposal Site & Impact on Remedial Action Plan.No Significant Agreements Reached at Meeting

ML20247B826
Person / Time
Issue date:	05/19/1989
From:	Lohaus P NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Bangart R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
REF-WM-54 NUDOCS 8905240253
Download: ML20247B826 (22)

Text

, _ _

RICHARD L. BANGART

-1 MAf 191999 MEMORANDUM FOR: Richard L. Bangart, Director Division of Low. Level Waste Management and Decommissioning, NMSS FROM:

Paul H. Lohaus, Chief Operations Branch Division of Low-Level Waste Management and Decommissioning, NMSS

SUMMARY

OF GRAND JUNCTION PROJECT MEETING Enclosed, for your information, is a summary of a meeting held in our offices on May 4,1989, with staff of the DOE Uranium Mill Tailings Project Office and their contractors. The meeting was held at DOE's request to discuss the results of additional characterization of the Grand Junction Cheney Reservoir disposal site and its impact on the associated proposed remedial action plan.

The meeting was strictly presentation of information; no significant agreements were made.

(StGNED) PAULH.LOHAUS Paul H. Lohaus, Chief Operations Branch Division of Low-Level Waste Management and Decommissioning, NMSS

Enclosure:

As stated Distribution:

Central File' t WM-542 a

RBangart, LLWM JGreeves, LLWM MBell, LLRB JSurmeier, LLTB PLobaus, LLOB MFliegel, LLOB DGillen, LLOB TJohnson, LLOB MWeber, LLOB JGrimm, LLOB JJones LLOB rf HMSS rf PDR YES /X /

i PDR NO

/ / Category: Proprietary / /

or CF Only / /

ACNW YES /Y 7 NO / /

SUBJECT AB5 TRACT:

Summary of 5/04 9 Meeting on Grand Junction UMTRA Site

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Oper@ns Smnch w as Meetng Notes U.$. Nuclear Requiotory Conrn..sson 5/05/89 D. GILLEN 1

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DOE / TAC /RAC UMTRA - Grand Junction 0"

One White Flint North:

4B-11 5/04/89

Purpose:

l To discuss additional characterization of the Grand Junction Cheney Reservoir sit and impacts to the remedial action plan.

eten6ed&

See Enclosure 1.

Item Description of Discussion Acilon 1.

Introduction:

The attendees were introduced and Karen Agogino

' (TAC Site Manager) briefly introduced the technical presentations.

2.

Geology / Hydrology:

Dale Hammermeister (TAC site hydrologist) described the Cheney Reservoir geohydrology as determined by the i

additional groundwater characterization conducted at the site.

l He presented contours of the top of the Mancos formation and cross-sections indicating the existence of paleochannels on both sides of the disposal cell footprint.

The channels contain an average of 2-3 feet of pe.rched groundwater of good quality.

Analyses indicate that geochemical attenuation, dilution, and travel time would not provide significant reduction of contaminant source concentrations (see enclosure 2).

Therefore, DOE proposed modifications to the engineering design such that the EPA standards could be met.

3.

Engineering Design:

Jack Caldwell (TAC) described & proposed disposal cell that would be designed to divert the paleochannel gravel aquifers and provide a sink for any seepage / infiltration.

Elements of the design would include:

1) deeper excavation of the cell into the unweathered Mancos, 2) an upstream permeable drain zone enclosed by Mancos dikes, 3) a large downstream Mancos dike,

4) a multi-layered cover system as previously planned, and 5) a corrugated cell floor to evenly distribute any seepage / infiltration.

In addition, Mr. Caldwell indicated that DOE plans to employ the

" observational method" through initial excavation of the cell in the form of an exploratory trench, firsthand observation of geohydrologic conditions, and modifications of remedial action to suit actual conditions (see enclosure 3).

4.

Discussion: Since everyone agreed that it was too preliminary to discuss the details of engineering design, discussion which followed the technical presentations focused on how DOE will procede from this point. NRC staff cautioned DOE of the potential impacts on other reviews that would result froJn multiple Grand Junction submittals/ redesigns. This would be deviating from the intended a_______.

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DOE / TAC /RAC UMTRA - Grand Junction I

if8m Description of Discussion Acilon i

cour$e of streamlining, i.e., consolidation of review steps. DOE concluded that they needed to get together among themselves to determine better their plan for RAP preparation in conjunction with the schedule for cell excavation. The NRC staff indicated that they had no objection to the proposed macro-characterization l

by trench excavation.

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FACTORS WHICH AFFECT CONCENTRATION OF CONTAMINANTS AT P0C CHENEY RESERVOIR I

SOURCE CONCENTRATION (HIGH)

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ENGINEERING DESIGN FEATURES

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EMTCT OF MLL SEEPAGE RATE CN (As) AT ICC Call Seepage Rate (As) at POC M1 1 x 10-7 W aec 1.13 mg/l 0.05 mg/l 1 x 10-8 W aec 0.30 mg/l 1 x 't. 9 W aec 0.04 mg/l

• Amannam Source (As) = 1.64 ag/l Seepage Gradient = 1 4

E : + y langth = 4.88 x 10 m Aquifer (As) = 0.005 mg/l Aquifer Gradient = 0.025 Aquifer Blickness = 83 m Aquifer Hydraulic 0:nductivity = 1.0 x 10-3 W sec

\\ e DESIGN CRITERIA 1. DIVERT / INTERCEPT GRAVEL AQUIFER 2. PROVIDE A SINK FOR SEEPAGE / INFILTRATION 3. MINIMIZE NATURAL INFILTRATION AND POSSIBLY TAILINGS SEEPAGE )

p 5 4 DOE UMTRA PROJECT GRAND JUNCTION CHENEY RESERVOIR EVALUATION OF ALTERNATIVE DISPOSAL CELL DESIGNS So MAY 1989

i ~ DESIGN OBJECTIVES A DISPOSAL CELL THAT i o COMPLIES WITH EPA STANDARDS o MINIMIZES ADDITIONAL COSTS o MEETS SCHEDULE & INSTITUTIONAL CONSTRAINTS I J

ADDITIONAL COSTS $10 6 o CHANGED LAYOUT 5 o ADDITIONAL COMPONENTS: FOR PERCHED WATER 5 o ADDITIONAL COMPONENTS: FOR MANCOS INFILTRATION 5 o TAILINGS CONDITIONING 5 NOTE: COSTS ARE ORDER OF MAGNITUDE ESTIMATES, ONLY. ACTUAL COSTS MAY VARY BY A LARGE PERCENT.

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USE OF THE OBSERVATIONAL METHOD 0 EXPLORATION - SUFFICIENT TO DEFINE PATTERN & NATURE OF GEOTECHNICAL DEPOSITS. O ASSESSMENT OF CONDITIONS - THE MOST PROBABLE CONDITIONS THE MOST UNFAVORABLE DEVIATIONS 0 ESTABLISH DESIGN - FOR WORKING HYPOTHESIS OF MOST PROBABLE CONDITIONS 0 SELECT CONDITIONS TO OBSERVE DURING CONSTRUCTION - ALSO CALCULATE ANTICIPATED VALUES FOR WORKING HYPOTHESIS AND ANTICIPATED CONDITIONS 0 CALCULATE VALUES FOR MOST UNFAVORABLE CONDITIONS 0 SELECT, IN ADVANCE, A COURSE OF ACTION OR DESIGN MODIFICATION FOR EVERY FORESEEABLE SIGNIFICANT DEVIATION OF THE OBSERVATIONAL FINDINGS FROM THOSE PREDICTED ON THE BASIS OF THE WORKING HYPOTHESIS 0. MEASURE QUANTITIES AND OBSERVE ACTUAL CONDITIONS 0 NODIFY DESIGN TO SUIT ACTUAL CONDITIONS .l

l GRAND JUNCTION - CHENEY RESERVOIR OBSERVATIONAL METH00 DECISION CHART i o START EXCAVATION o EXCAVATE AS o VERY UNFAVORABLE CONDITIONS EXPLORATORY TRENCH - UNW. MANCOS VERY DEEP l - EXTENSIVE WATER INFLOW - UNW. MANCOS LESS PERMEABLE I THAN COVER m o OBSERVE DISTRIBUTION 0F SOIL STRATA & WATER - PROFILE WEATHERED MANCOS - PROFILE UNW. MANCOS - WATER IN GRAVELS - FLOW RATES ABANDON SITE o' COMPLETE PIT EXCAVATION h y OBSERVE SUBSURFACE DESIGN MODIFICATION CONDITIONS 4 o - DISCRETE GULLYS WITH o MODIFY CELL FOOTPRINT TO AVOID SIGNIFICANT WATER 7 GULLYS AND FLOW o INSTALL OUTER PERIMETER DRAINS o INSTALL INNER PERIMETER DRAIN 4 o UNWEATHERED MANCOS: o CONSTRUCT EXCAVATION m - VERY LOW PERMEABILITY BASE ZIG-ZAGS ~ - VERY LOW ACCEPTANCE o INSTALL PERCOLATION HOLES h o HORIZONTAL PERMEABILITY 0F MANCOS VERY HIGH P o CONSTRUCT BASAL LINER o SHORT CIRCUIT FLOW INTO AND OUT OF CELL POSSitLE 0 o TAILING AT PROCESS MG o DRY TAILINGS SITE VERY WET 7 o PLACE TAILINGS AT LOW MOISTURE CONTENTS o TRANSIENT DRAIRAGE A i POTENTIAL PROBLEM ] 4/28/89 JAC

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