ML20055H098
| ML20055H098 | |
| Person / Time | |
|---|---|
| Site: | 07000371 |
| Issue date: | 07/18/1990 |
| From: | UNITED NUCLEAR CORP. (SUBS. OF UNC, INC.) |
| To: | |
| Shared Package | |
| ML20055H086 | List: |
| References | |
| NUDOCS 9007250198 | |
| Download: ML20055H098 (12) | |
Text
_ _ _. _.
UNC NAVAL PRODUCTS DMCOMMISSIONING PLAN ATTACEMENT A-Page Al Rev. 1 Dates 7/18/90 Analysis of Sectic Leach Field for Decommissionina Introduction From 1958 to 1987, UNC~ discharged its sewage to an onsite septic systan, cince no municipal sewage system was available.
A new septic field was initiated in 1973 south of Building A.
Beginning in April, 1974, discharges to that newer system includsd licensed discharges of low levels of SNM which had been processed through our liquid rad waste treatment facility.
In>1978,-an addition was added south of the original 1973 field in order to increase capacity..This le presented-in Exhibit 1.
The combination of these two fields will be identified as "the leach field" throughout this l
report.
The use of the leach field continued until November, 1987 when l
UNC initiated discharge of radioactive waste water to the new Montville ocwor system per NRC Condition No. 27 to SNM License 368.
I This plan presents the survey methods which will be used to evaluate the leach field in order to allow decommissioning of the field.
The following documents were utilised in prtparation of this plan.
NUREG/Ck~2082
" Monitoring For Compliance With Decommissioning n
Termination Survey Criteria".
(_/NUREG/CR-5512
" Residual Radioactive Contamination From DecommissioningH I
Draft Report.
General Decommissioning Plan refairenced in Condition No. 19 to Materials License SNM-368.
J'ield Layout l
l Ao stated above, the Leach Field can be divided into two sections.
l L
1.
The original field sus fed by a main incoming line to a master distribution box (see Exhibit 2).
The wasta stream was split at this poinc into a pair of two parallel feed lines which ran the length of tho field.
A series of leaching pipes run perpendicular to the feed Jines.
These leaching pipes have a series of holes which permits the caterial to uniformly leach into the ground.
Each leaching pipe is l
laid in gravel to assist in the leaching.
The leaching pipes are I
estimated to lie from 2 to 6 feet below the soil surface with the l
variance due to the slope of the land and additional clean fill added during the 1986 building construction.
This field will be called Fiald 1 throughout this report.
f.
The 1978 field addition was placed immediately south of the original system.
This addition was fed by a feed line which was connected to the master distribution bou and led into a secondary distribution point.
Two lines led from this second bcx, each to yet another box.
O Bach tertir.ry box fed six dry wells which vere positioned around the box.
9007250198 9007 0 PDR ADOCK 07000371 C
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UNC WAVAL PRODUCTS DECOMMISSIONING PLAN ATTACEMENT A f
Page A2.
kev. ' 1 Dates 7/18/90 FielG Layout continuedt j
Exhibit 3 shows these twelve dry wells.
Each dry well is 12' deep and.
has an inside diameter of 5-1/2'.
The well has a series of holes i
?
completely around the periphery which permits the leaching (see Exhibit 4).
Approximately 28 of gravel surrounds each well to aid in the process.
This field will be cellse Field 2 throughout this report.
Statistical-Basig
'Por NUREG/CR-2082,.at least 30 sample pcints shall be obtained in each field.
A statistical test at its 95% confidence level will be performed cn the data to assure that the sample is an adequate approximation of thw pcpulation.
Failure to obtain an adequate sample will cause additional 2:asurements to be taken until the criteria.is tat.
i Background Sampling The first step of the survey plan is to determine the radiation background lcvels of the site.
This will include both beta-gamma measurements at the curface and gamma measurements at 1 meter.
Thirty background measurements
.will be taken from various locations both close to the field and cignificantly away.from the field.
Locations will be chosea which are 311eved to have relatively the same soil and rock composition (primarily.
gravel and sand) as the leach field.
L The second part of the background sampling consists of soil analysis.
Fcur holes will ba drilled at random locations to the south and east of l
the leach field.
Two holes will go down 15' while the other two will be L
drilled to the water table (approximately 20 - 24 feet).
Samples will be tcken every three feet for analysis.
As above, locations will be chosen which best reflect the soil located in the leach field.
This data vill be L
coded to the two background samples which were taken in 1985 (Report to l
W.T. Crow from W. F.' Kirk dated 10-29-85).
Therefore the soi'l from a total of six holes will be inclue.od 4 the data.
Although less than 30 background sample points are used, the total number of background soil camples for analysis will exceed this value.
A3.iace Radioactivity Level Samnlina Fisid 1 i
A series.of 10 meter I 10 meter grids will be marked off to completely encompass Field 1 (See Exhibit 5).
The starting point for the grids will be a. location five fest erst and ten feet south of'the southeast corner pipe.
surface beta-gntma readings will.be taken at every grid
.pointLand at the approximate center of each grid.
Additionally, gamma readings will be measured at 1 meter from the surface at all
[}'
locations.
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L UNC NAVAL PRODUCTS DECOMMISSIONING PLAN ATTACEMENT A p,j%c p
Page A3 Rev. 1 Dates 7/18/90 L
Surface' Radioactivity Level Samnlina continue (
Field 1 A series of-5 meter I 5 meter grids will be marked off to completely encompass-Field 2 (See Exhibit 6).
The starting point for the grids-will'be the secondary distribution box.
Identical measurements to.
those stated above will be taken at each grid. point.
Measurements will not be taken'at the center of each grid due to the smaller grid area.
Both Fields' A general walk over survey will also be performed in both fields in order to verify the absence of any technologically enhanced areas of J
radiation.
Should.this not be verified, the identified areas will be included in the soil sampling discussed below.
soil smanlina soil samples will be sent to an outside laboratory where they-will be blended and analysed for UNC.'
In addition, the samples will be split' at the vendor _if NRC/ORAU or CT. State DEP should request any samples.
()MeterReadingsAboveBackground All locations (if any) which demonstrate an 6.bove background reading during the surface sampling discussed above, shall be subject to soil sampling.
"Above background" will consist of those measurements which i
exceed the mean background level at the 95% confidence level. -These samples may.be included as part cf the randon' sampling discussed below.
Any locations which are above background due to proximity.to fuel handling buildings will not require soil sampling.
Field 1 Svatematic 8==nline Ten locations will be chosen based on technical knowledge of the field.
Moles will be dug at these locations with care not to' hit any pipes.
Every hole trill penetrate at least 12' with every fifth hole being dug down to the water table where the ground water shall also be obtained'for sampling.
Soil samples will bo taken every 24".
[
Randon 8mmnling: Another twenty grid points will be randomly chosen from the griG-shown in Exhibit 5.
Addf.tional random grid points will also be selected in case an inaccessible location is initially i-chosen. _An inaccessible. location would be that covered by a very large boulder or by a concrete slab'but would not.includa soil covered l
by blacktop.
sampling will occur as stated above.
The combination of O
the systematic and the random samplirq proviums for 30 sampling 4
locations.
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.I UNC MAVAL PRODUCTS DECOMMISSIONING PLAN ATTACHMENT-A Page A4 Rev. 1 Dates 7/18/90 i
soil n==lvsis continued - Field is Pine'Analysist.In addition, following the soil sampling, the pipes
.will be individually sampled (see Exhibit 7).
The locations 1 designated as L1 through L7 will be excavated and the sludge (if
.present) will be sempled.
Also, twelve leach pipes will be randomly-selected by number for sampling.
Each number chosen shall be sampled at locations near the feed line and out near the end of the pipe.
Thus a total of 31 pipe locations will be analysed.
care will be exercised to prevent any potential contamination from leaving the i
L broken pipe and entering into the adjacent soil.
Field 2 Systa== tic E==nlinat The soil above and below each well (W1 through W12) shall.be sampled.
Holes will be dug at these locations down to the water table where waier samples will be obtained.
Soil samples will be taken;every 24".
L Randon Sampling Eighteen grid points will be randomly chosen from the L
. grid shown in Exhibit 6.
Holes will be dug down 20 feet or to the.
l-water table, whichever is higher.
If a grid point is above the gravel L
which-surrounds the walls, the hole shall be dug just-outside the E -
gravel since the auger can not penetrate through'the rocks.
If the L.
grid point falls over a well, a new random point shall be selected since'the soil in the walls is being sampled under " Systematic sampling" listed above.
Inaccessible locctions will be treated as in Field 1.
.The combination of-the systematic and random sampling makes a total of thirty sample locations.
Well Analysist In-addition, all walls and distribution boxes (W1 L
through W15) will be sampled.
This sampling will consist of sludge collection and subsequent..eter analysis at varying depths within the well or box.
Related Ecuinment The-main discharge pipe, the 5000 gallon septic tank, and any other rolated. equipment not discussed in this report will be evaluated under a
- ceparate project.
These equipment items are still required for the present discharge system.
These will be sampled at the end of the decommissioning effort in accordance with the criteria discussed in the D: commissioning Plan.
Hazardous Materials Soil samples will also be analysed for the presence of various hasardous caLJrials to assure compliance with all applicable regulations.
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'UNC NAVAL PRODUCT 8 DECO 30tISSIONING PLAN ATTACMMENT.'A Page A5
-Rev.
1.
Dates 7/18/90 Analysis And Instrumentation The general _ walkover survey will be taken with a uR meter.
Soil samples will be taken using a 24" split sampler and other standard excavation
- equipment. -All soil analysis will be performed by a properly certified outside laboratory.
soil samples will be measured for gross alpha.
selected samples will be further analysed for total Uranium and in some cases) isotopic analysis shall be performed.
Several samples will also be
'ecked for additional. isotopes including radium 226.
. The' acceptable alpha radiation release level for soil at UNC will be as stated in the Decommissioning Plan.
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a UNC NAVAL PRODUCTS DECO 30tISSIONING PLAN
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UNC-NAVAL PRODUCTS DECONNISSIONING PLAN
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UNC NAVAL PRODUCTS DECONNIBSIONING PLAN ATTACEMENT A.
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- UNC MAVAL PRODUCTS DECOMMISSIONING PLAN ATTACEMENT &
'Page A12 Rev. 1 Dates 7/18/90 EXHIBIT 7 - FIEl D 1 PIPE SAMPLiliG
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