ML20006E891

Trip Rept of 900213 Visit to West Valley,Ny Re Solvent Interceptor Trench Constructed by DOE

ML20006E891
Person / Time
Issue date:	02/22/1990
From:	Pittiglio C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Boyle R, Surmeier J NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
REF-WM-3 NUDOCS 9002260499
Download: ML20006E891 (12)

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iMEMORANDUM-FOR[ Regis R.. Boyle,1 Acting Chief-Regulatory Branch -

FEB 21 1990 i

Division of Low-Level Waste Management and Decomissioning, NMSS Johi J. Surmeier, Chief Technical Branch Division of Low-Level Waste Management.

V and Decomissioning, NMSS FROM:'

Clayton L. Pittiglio, Jr., Project Manager Regulatory Branch

l Division of Low-Level Waste Management

- and Decomissioning, NMSS

SUMMARY

OF SITE VISIT TO WEST-VALLEY, NY 1

': b I have attached sty trip. report that sumarizesL tho NRC-staff's observations resulting from the inspection of the solvent interceptor trench that is being

-l constructed by DOE at the West Valley site.

Included with the attached trip

' report.are Enclosure 1 and Enclosure 2.

These enclosures provide a more

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-detailed discussion of the observations and conclusions discussed'in nly trip j

' report.

Enclosure I was prepared by Jack Parrott and Enclosure 2.was prepared -

.by Joe'Kane..

If you have anyy questions regarding the inspection of the interceptor trench 2

at West Valley, please contact Jack Parrott (X-20565), Joe Kane (X-23449) or ntyself (X.23438).

P Original signed by 5'

Clayton.L. Pittiglio, Jr., Project Manager Regulatory Branch Division of Low. Level Waste Managenent and Decomissioning, NMSS

Enclosures:

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t 51-3 WEST VALLEY DEMONSTRATION PROJECT E

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TRIP REPORT February 13, 1090

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WESTERN NEW YORK SERVICE CENTER V

t Prepared By: ~ LClayton L. Pittiglio, Jr., LLRB/LLWM/NMSS

Date

.

February 13,'1990-Location:-

' West Valley, NY.

~

Purpose:

. EVALUATE.THE CONSTRUCTION OF THE INTERCEPT 0R TRENCH I

Attendees::

D. Hurt, NRC W. Bixby, DOE C. Pittiglio, NRC E. Maeston, DOE L

J. Kane, NRC B.. Lawrence, WVNS J. Parrott, NRC T. Weiss, WVNS R. Garland, WVNS

1 B. Blickwedhl, WVNS/D&M.

.1

Background:

The previous' operator, Nuclear Fuel Services, of the reprocessing facility at West Valley (figure-2-1), disposed of a radionuclide 5

contaminatedsolvent,n-dodecane:(kerosene)andtri-butyl ~

phosphate (both currently considered nonhazardous), in the NRC' l

~ Disposal: Area 1(NDA) in 22 known 1000 gallon: carbon steel tanks-in eight:"special holes".or burial holes-from 1968 to-1972.

l Figure 4-1 shows the> locations of the tanks.

In November of 1983, solvent was detected in a. monitoring.well.

1 just outside-the NDA area and subsequent investigation revealed ground-surface contamination:around two of the special holes.

DOE carried out an. exhumation, stabilization, and repackaging program on the two.special. holes (SH-10 and 11), including the removal of eight tanks, their contents and the material around them. Only 430 gallons of the 4000 gallonc of' solvent-originally-disposed of in these.two. holes was recovered. The remainder of the solvent had migrated.

On November:14,1989, more radionuclide contaminated solvent was detected in monitoring wells to the north of SH-10 and 11 4

approximately 40 feet from ravines of the small tributaries to-Buttermilk Creek watershed, a source of public water supply. As a result of the' detection of this solvent, an engineered

. k interceptor trench to contain the migrating solvent plume within-the' area of current expansion and within the vicinity of the NDA f

is,being. constructed by D0E. Figure 7.1 shows the location.of n o 1

the interceptor trench and Figure 7.2 shows the design. DOE considers this an appropriate maintenance expense necessary to operate the NDA facility in a manner that will protect public I

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health and safety within the scope of the WVDP Act. DOE stated.

that the trench construction would be completed by August 1990.

i DOE is recommending follow-up action for long term remediation l

l' of the' source term in the area.

Long-term remediation could-include removal, exhumation or stabilization of the solvent-still remaining in the buried tanks.

l Observations: While inspecting the trench ~ construction at the West Valley site, the NRC staff raised a concern regarding the chemical compatibility of the solvent with the proposed geosynthetics.

The NRC staff was also concerned about the construction quality resulting from placing the trench drainage pipes and backfill materials-from the surface. The NRC staff recognizes that this method'of trench construction will greatly reduce radiation exposure for field personnel, but requests additional care to 1

assure needed quality construction.

Figure 7-2-shows a typical; cross-section lof the trench.

The NRC staff observed that the current cap does not appear to be-well maintained.

The cap had several areas which had settled

.or washed out, resulting in retaining water rather.than having the water-runoff. NRC staff believes that a well' maintained cover over the disposal area will greatly reduce water

' infiltration.

More detailed descriptions of the staffs observations and discussions during the February 13, 1990,. site visit are 4

,provided in Enclosure 1 and Enclosure 2.-

==

Conclusion:==

The NRC: staff concluded that the construction of the-interceptor trench is a positive interim measure for controlling-the migration of the solvent and should proceed to completion.

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s SiteLVisit Report - Feb. 13, 1990 West Valley Demonstration Project Interceptor Trench at NDA Area By: Jack D.

Parrott, LLWM, LLTB, Feb. 20,.1990 observations 1.

Fill material contaminated by radionuclides was encountered on the north side of the sump excavation.

This.is tha side opposite the leaking solvent tanks and is outside the NDA area.. According to site personnel the fill material consisted of tree: trunks and gravel'among other things.

Fill material of this type has the potential.to greatly increase penaeability in the shallow till-zone.

2.

The radioactive species contained in the contaminated fill material had not been determined but according to site personnel the contamination was not due to tho' solvent leaks.

3.- No water was observed to be draining into the completed portion

' of the trench from the till, it appears that earlier water problems were indeed caused by surface drainage during precipitation events.

Recommendations 1.

Determine types and amounts of radioactive contamination that occurs in areas of fill outside NDA area.

2.

Long term solution to containing contamination problems at NDA area -require a better understanding of the - geology of and groundwater flow through the till.

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a SITE VISIT REPORT - Feb. 13, 1990 WEST VALLEY DEMONSTRATION PROJECT CONSTRUCTION OF INTERCEPTOR TRENCH FOR SOLVENT CONTROL

' Prepared by : J os,e ph D.

Kane, LLWM, LLTB a

OBSERVATIONS AND DISCUSSIONS

1. The excavation and the on-going construction for Manhole No.5 were ' observed.

Both the weathered and the -' unwea thered _ gIacial

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tills were viewed on the slopes and on the bottom of the manhole i

excavation.

The - wea thered-til I consisted'of a dark-brown,. moist i

to wet clayey silt with occasional rounded gravel pieces imbedded ~

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in the till and one thin steeply sloping sand' lense was visible on the slope of the excavation.

The weathered till appeared to be j

stiff'and capable'of standing on near vertical slopes.~. Occasional thin vertical fissures

(< 1/16 inch) were visible on the slopes of

. the excavation.

The cause (e.g., f rom dessication cracks or stress

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relief) of the-fissures is not readily apparent.

4 The unweathered til1 was observed to consist of a wet, plastic and 4

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stiff dark gray clay with occasional rounded gravel pieces.

'The

~ highly cohesive nature of -the unweathered till results in 'the formation'of large blocks and clods as it is excavated. -The stiff 1

'unweathered till also reflected fissures :and ' appeared stable on_.

- near vertical excavation slopes.

i 2 'The subsurface contact between the' weathered and'unweathered till that is shown on the profile drawings for the construction of-the-interceptor trench was established by; a series of borings that were drilled along the proposed trench alignment.

The location of the borings, although not-shown on the-profiles, can be discerne L

- from the points where changes in the contact surf ace occur on the profiles.

The logs of the borings were not available at te February 13, 1990 meeting.

3. In response to an NRC *1 wf f question whether presently available information and data exist to detect a ' water level response in L

observation holes within the NDA disposal area to significant precipitation events, DOE's consultant indicated that the wells i:

appear to reflect a direct response to precipitation events but 4

site characterization information for the NDA'is limited and not i

conclusive.

DOE's consultant did indicate that the NY State L

regulated disposal area has extensive information on the L

relationship between water level fluctations in response to I

precipitation events.

4 The pervious granul c

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backfill'of the-interceptor trench'is_NYS DOT'No. i stone.

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j istone visually appears to be similiar. to pea gravels, is uniformly.

!k gradedfwith maximum sized particles in the range-of 1/4 to 1/2 Linches.

In' response to the staf f 's Ques tion on what brecing of the excavated trench is-planned, it was indicated that all trench Ji operations:are to be performed.from. ground surface'and bracing of the near' vertical slopes would not be required.

This construction sequence.1s being followed to minimize worker exposure.

This'is understandable, but-quality and, control of construction will be' significantly limited because of the restrictions from working at the ground surface.

5. During this site visit the condition of'the soil cover over'the wastes in the NDA' area was coser0ed from outside the fence of the restricted area.

The NDA cover surf ace appears to be poorly graded for minimizing surface water infiltration with some low retention berms,and stockpiles of previously excavated soils on the ground-surf ace contributing-to increased infiltration. Some surf ace-areas -

in the NDA were observed to consist of pervious gravel areas ~that had been placed to f acilitate movement of equipment during previous ac tivi ties. ' ( e.g., removal of previously leaking solvent tanks).

These pervious' areas on the surf ace act to retain water rather-than minimize infiltratien.

The poor cover conditions at the NDA site'

. stood.in contrast to the more positively drained and vegetated cover-system at the NY State licensed disposal f acility.

The.

condition and grading of the cover system over the NDA area is considered to be an important concern that would-need to be acceptably addressed in the EIS.

L RECOMMENDATIONS b

1., Construction of the interceptor trench should proceed and is considered to be a positive interim-measure for controlling the migration:of the~ solvent.

The existing condition of the NDA area requires early attenticn and improvements-and will involve major remedial' measures to ensure long-term stability.

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2.

DDE was encouraged to check the: chemical compatibility

-(resistance) of the geosynthetic materials (PVC

pipes, HDPE membrane, and geotextile f abric) proposed in the interceptor trench construction against deterioration when exposed to the waste.

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3. The glacial'till is proposed to be used as the impervious fill p

e where this - material is required as backfill in the interceptor 1

trench construc tion.

Because of its stif f and cohesive nature that results in the formation of large blocks and clods when excavated, conditioning =(e.g., processing to eliminate the blocks and clods to manageable particle sizes for proper compaction) of the till is considered by the staff to be necessary.

'4. The construction plans for the interceptor trench call for the installation of 2-inch diaceter PVC standpipes to monitor the presence of any liquids in the trench.

The NRC staff suggested 4

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that.: consideration : be : given toL : installing - a collar arrangement :

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t around--the L standpipes to i~mpede water: 1 rom infil trating :around;-the Y:f,

pipe annulus.--This-' annular space is-often a s

preferred; pathway 1for; infi1tration'and could.be minimized:-by a simpie modification such

. as sea l ing -' a piece of. impermeable membrane!around--the: pipe where i t' is': imbedded Lin; the. compac ted. c lay cap.

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Figure 7-1. Conceptual layout of interceptor trench system.

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