[SUPPLEMENTAL FIELD INVESTIGATION PHASE IV, AND ...

MEMORANDUM

File

R. D . Gtbbs

Supplemental Field InvestigationPhase :ff April 28 - May 7Installation of Deep Borings to ExamineMine Void CharacteristicsMonitoring Well Installations

During the first half of the 10 day work cycle IT Corporationconducted a portion of their mine void investigations. A total of 11borings were drilled and more would have been drilled except ITCorp. stopped the mine void investigation when Brad King from Geraghtyand Miller arrived on site. Brad is a hydrogeologist fot Geraghty andMiller and he arrived on May 2 to oversee the remainder of the wellinstallation. At that time the drill rig was committed to installingthe wells.

HINgLVOIP OTESTrCATION

The IT Corporation work plan outlines the investigation as follows;

The objective of this investigation is to obtain information to providedata on the approximate configuration of voids related to previous under-ground mine workings adjacent to the site (i.e., voJ.d configuration,height, pillar spacing, etc.). A series of 5-10 byrings will be installedon either side of the initial boring along an east-west and north-south line.

Taci/ f<; - In the location selected for monitor well Cluster 3(see IT work plan Phase V) use mud or air rotary drillingtechniques to drill up to 5 pilot holes to locate a rainevoid for Investigation.

After locating the void, install a series of borings(up to ten) on either side of the pilot hole in an eastto west and north to south direction, spaced 5 t? 10 feet

Task 17

apart. These borings will be drilled with air or mudrotary.

A general description of the mine void investigation is provided sincethe actual work was diffecant than what was in the IT Corporation workplan. The attached sketch shows the location of the mine void invest-igation. A brief description of each boring is provided to give specificdetails about what was found in the 1 1 borings.

003672

B L A C K & V E A T C

Kerno randum May 21, 1987

IT drilled the first boring in the general area where Well Cluster 3teas to be located (see IT work plan Phase V), They fr/und a mine voidand ground water partially filled the void zone. 'IT later located thedeep monitor well for Cluster 3 (MW103D) in this first borehole. Thisfirst mine void boring was called MVB-1.

ZSie second mine void boring (MVB-2) was off-set 20 feet to the southof the first boring and a small amount of coal was found. No minevoid was encountered in the boring.

At this time, IT deviated from the work plan as they did not offsetthe next boring on either side of the pilot hole, IT stated theythought there would be aore benefit to the project if IT moved to adifferent area completely, since a void had been found with the firstboring. The next boring MVB-3 was located in the offsite area approx-imately 100 feet to the northwest of MVB-1.

Mine void boring four was bored in an entirely different area than thefirst three. This area was later identified as Well Cluster 5. The deepmonitoring well for Cluster 5 (MW104D) was eventually installed inMVB-4.

The rest of the mine void borings were in a different location in theoffsi te area just north of Well 09B as indicated located on the attachedsketch. These borings were offset 20 feet from one another in a patternsimilar to that described in the original work plan. Detailed informationon these borings is contained in the description of MVB-5 through MVB--H.

Ail of the mine voids eventually showed signs of moisture when water levelmeasurements were taken several days later.

In summary, four different areas offsite were investigatedinstead of one area, which was outlined by the work plan. The Investigationin two of these areas consisted of only a single boring. The attachedsketch shows the locations and pages 40-44 in the field logbook givespecific information about the borings. Th<5 characteristics of the minevoid borings are listed below:

o MVB-1 " This mine void boring was located in ClusterWell 3 as indicated in the IT work plan. Prom 0-10.5 feetoverburden material waa found. g'rom 10.5 to 60 feet theshale material was dry. Water was found in the boreholeat 60 feat. A sine void was located between 66-71 feat. TheIT site geologist used the following criteria for identifyingthe extant of a mine void;

Steady drilling to a sudden drop of the drill rodRa-estabiishing drilling in solid material

003673

S L A C K A V E A T C

Memo rand urn May 21, 1987

The vertical extent of the mine void was estimated to be 5 feet,Groundwater was first found at 60 feet and was identified between60-71 feet. The IT site geologist had the drill crew core from71-75 feet, where shale was found. IT decided later to installWell C-3-D (MW103D) in this boring.

MVn*-2 - This mine void boring was offset 20 feet south of MVB-1.The first 13 feet of thia boring was overburden material* Moisturewas found at 60 feet in the boring. Coal was encountered at 67feet. Not enough coal was recovered to take a sample making itdifficult to predict the actual thickness of the coal seam. Thesite geologist had the drill crew core from 67.5 - 71.5 feet.No mine void was found in this boring*

MVB-3 - The boring was located in the offsite area NW of thesite. Clay overburden material was found in the boring from0-9.5 feet. The first sign of moisture in the borehole wasfound at 70 feet. Water was flowing into the hole at 77. feetand thera was a mine void found between 73-74 feet. Anotherseries of voids were found between 74-79.5 feet. This wasdetermined by the IT site geologist as he observed the criteriafor establishing a mine void listed in the MVB-1 description.The* drill/drop sequence was observed several times in this boring.

^VP-A - The boring was located offs i te , north of existingmonitoring well 04 and 50 feet north of MVB-1. From 0-6 feetthe boring went through overburden material. Moisture wasfound in the hole at 35 feet. The hole produced water at 40 feet.A mine void was found between 80-83 feet and drilling was stopped.This borehole was the only one of all of the borings to identify waterin the bedrock above the coal seam. Monitoring well C-5-D (MW1040)was later installed in this borehole.

MVB-5 - This was the beginning of a series of borings in locationin the offsite area north of monitoring well 09B. Overburdenwas found in the borehole from 0~l5 feet. Shale was encounteredat 15 feet into the boring. A mine void was located from 47-54.5Eeet. The site geologist for IT said there wad an H2S odor present.Wate*" was not encountered in the boring. IT came back cwo daysafter the boring was completed and photographed the hole bylowering a camera on a PVC pipe into the hole. Copies of the photoswere provided to ths oversight representative.

JJ^B-^ • The boring was located 20 feet south of MVB-5. Clayoverburden was found in the boring between 0-15 feet. A minevoid was found between 43.5-47.5 feet. The borehole remaineddry, no water was found. This borehole was also photographedby IT and copies provided to tha oversight representative.

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HVB-7 - The boring was drilled 20 feet south of HVB-6. Clay over-burden was found in the hole between 0-16 feet. The shale layerstarted at 16 feet. Coal was found in the borehole at 41 feet.The boring was cored and the coal seam was between 41-48 feet.The IT site geologist took a split sample of the coal foe EPA.The oversight representative labeled this sample MVB-7.

MVB"8 - This boring was located 20 feet south of MVB-7 and hadoverburden between 0-20 feet. Shale was encountered at 20 feet,At 40"45 feet there appeared to be a mine void or at least somekind of disturbance at this depth. This was determined by theIT site geologist. The borehole was dry and no water was found.

MVB-9 - This boring located 20 feet south of MVB-8, was thefarthest to the south and closest to the pit area. Theboring went to 22 feet where the drilling became difficult andIT decided to discontinue the hole at that time. Trash-likematerial and wood scraps were brought up from the hole.

WB'10 - The boring was located 20 feet east of MVB-8. Slltyclay and refuse along with wood scraps were found from 0-10feet. From 10-15 feet in the borehole overburden materialwas found. At a depth of 40-42 feet the drilling became easierand sample returns were lost. The IT site geologist thoughtthat a mine void started at approximately 38 feet.

MVB-11 - This boring was located 20 feet west of MVB-8. In thisboring silty clay was found up to 1.7 feet. At 36 feet the drillingbecame easier and the IT site geologist identified a mine voidbetween 36-42 feet. Specific mention was made by the T.T sitegeologist that this void was clay filled based on observation ofthe drill cuttings.

MQ^TORING WELL INSTALLATION

The a<scond half of the work period consisted of installing the remainderof tho monitoring wells.

The following wells were installed during this work period:

DeepShallowIntermediaeaDeepShallowDeep

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Memo randum May 21, 1987

Table 1 lists pertinent data related to the monitoring wells installed byIT Corporation during this and the previous phases of the field work. Waterlevels were measured on May 6 and IT plans on surveying in the well locationsand elevation during Phase V. At that time the water levels can be convertedto actual elevations. Also attached is a copy of the well installation logsthat the Geraghty and Miller hydrogeologist prepared for the wells that wereinstalled during this work period.

vmAttachment

cc: Tony GardnerDick MoosClyde HutchisonRay Herzog

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trtXL

Designation Designations Depth Water Level Tnf^n^i

inCluster tf2

C-2-S 101S 22 12.38

C-2-D IOID 43,5 37.58

0Cluster rf3 .... -- - -'C-3-S 103S 30 DryC-3-I 1031 50 DryC-3-D 103D 67 62.09

Cluster /M

Cluster ^5

C-5-S 10/tS 42 35.67C-5-D 104D 83 56.31

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Table 1

T\Vf'T/^1ilA 'PTrtITUt'.b-LGNA H.UN

DrilledCluster Monitoring Well To ScreenCluster Monitoring Well To

(ft) (ft)Cluster 1

C-l-S 102S 40.5 19.56C-l-D 1021 75.5 i

-4"S 100S 24.5 16.42

"^D 100D 58 40.35

(void)80-83

III

(ft)

25-4055-75

9.5-19.533-43

15-3040-5057-^7

10-20

44.5-54.5

2775

"42-83

mcy-

000

'

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WELL CONSTRUCTION LOG

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WELL CONSTRUCTION LOG

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^1^'GERAGHTY^Y& MILLER. INC.

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^STGERAGHTY^MILLER, INC.'tfouneS- Weier Coiwsisanis

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