area iv bedrock investigation at the fsdf field sampling plan … · 2018. 5. 14. · 1 area iv...

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Area IV Bedrock Investigation at the FSDF – Field Sampling Plan Addendum

Prepared by CDM Smith for the US Department of Energy

April 12, 2018

DOE is conducting a source investigation at the Former Sodium Disposal Facility (FSDF) in Area IV of the

Santa Susana Field Laboratory to determine the source of volatile organic compounds (VOCs) in

groundwater. This Field Sampling Plan (FSP) Addendum covers field activities related to drilling,

coring/sampling, and well installation in shallow bedrock at the FSDF.

Shallow near-surface bedrock well RS-54, installed to 45 feet below ground surface, exhibits elevated

concentrations of trichloroethylene (TCE) and 1,1,1-trichloroethane (1,1,1-TCA). RS-54 is the only

shallow boring at the FSDF providing data on the VOC source. Well RS-54 monitors groundwater in near-

surface bedrock fractures. Deeper wells near RS-54 currently do not show elevated VOC concentrations

indicating that the primary source is in near-surface bedrock. This FSP Addendum is focused on

collecting data on the extent of the shallow VOC source at the FSDF.

1.0 DATA QUALITY OBJECTIVES

The overall Data Quality Objectives (DQOs) for the FSDF open bedrock wells are to determine the

horizontal and vertical extent and distribution of contamination in shallow bedrock groundwater,

determine the amount of contamination entrained in the shallow bedrock matrix, and determine the

location and extent of fracturing in shallow bedrock.

A total of eight core holes will be advanced at the FSDF at the locations specified in Figure 1. These

locations are described below along with the specific DQOs for each location.

Location ID Location Description Data Quality Objectives

C-1 N of MIP boring A5 and down dip of RD-23, in western drainage feature*

Determine if TCE and 1,1,1-TCA contamination has migrated in bedrock fractures downgradient from the lower FSDF pond within the western drainage feature, and to delineate the downgradient edge of bedrock contamination to the N. Fracturing is expected to be more prevalent just above and below shale/siltstone beds.

C-2 NE of MIP boring AA8, between SSG-1 and SSG-12, in central drainage feature*; along strike from RS-54 and previous core hole C-08

Determine if TCE and 1,1,1-TCA contamination has migrated in bedrock fractures downgradient from the lower FSDF pond within the central drainage feature, and to delineate the downgradient edge of bedrock contamination to the NE. Fracturing is expected to be more prevalent just above and below shale/siltstone beds.

C-3 S of MIP boring B9 and up dip of C-1, in eastern drainage feature*

Determine if TCE and 1,1,1-TCA contamination has migrated in bedrock fractures downgradient from the lower FSDF pond within the eastern drainage feature, and to delineate the downgradient edge of bedrock contamination to the N/NE. Fracturing is expected to be more prevalent just above and below shale/siltstone beds.

C-4 W side of lower FSDF pond, N of MIP boring E3 and down dip of RS-54; along strike of C-1 and western drainage feature*

Determine TCE and 1,1,1-TCA concentrations in bedrock fractures at the downgradient edge of the lower FSDF pond. Fracturing is expected to be more prevalent just above and below shale/siltstone beds.

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C-5 SW corner of lower FSDF pond, NW of MIP boring G4, in area of mapped fractures

Determine TCE and 1,1,1-TCA concentrations in bedrock fractures mapped at this location.

C-6 E side of FSDF ponds, N of MIP boring H9

Determine TCE and 1,1,1-TCA concentrations in bedrock fractures on the E side of the FSDF ponds.

C-7 SW of FSDF ponds, between MIP borings M1 and K0, along mapped fractures and shale/siltstone beds that are along strike from C-5

Determine TCE and 1,1,1-TCA concentrations in fractured bedrock in the southern area of the FSDF, in areas of mapped fractures and shale/siltstone beds. Fracturing is expected to be more prevalent just above and below shale/siltstone beds.

C-8 Between PZ-101 and S side of FSDF ponds, NE of MIP boring K5, near mapped fracture and shale/siltstone beds; along strike from C-6

Determine TCE and 1,1,1-TCA concentrations in fractured bedrock in the southern area of the FSDF, in areas of mapped fractures and shale/siltstone beds. Fracturing is expected to be more prevalent just above and below shale/siltstone beds.

Notes:

Previous studies indicate that fracturing is more prevalent just above and below shale/siltstone beds

*Drainage features occur along strike of shale/siltstone beds

2.0 FIELD PROCEDURES

Eight boreholes will be advanced and completed as open bedrock boreholes at the locations shown on

Figure 1. Field procedures for drilling, sampling, well completion, lithologic logging, and development

are described below. All field activities will be conducted in accordance with the Site-Specific Health and

Safety Plan (HASP).

2.1 Bedrock Drilling, Sampling and Well Completion

Six-inch-diameter surface casing will be installed through overburden and approximately 2 to 4 feet into

bedrock and grouted in place. Once the grout has been allowed to cure for a minimum of 12 hours,

bedrock coring will be performed at 5-foot intervals past the outer casing using wireline rock coring

methods to produce a continuous HQ-sized (2.5-inch diameter) rock core. Immediately upon retrieval

from the core barrel, each rock core will be placed in aluminum foil-lined tray and scanned using an ID

for the presence of VOCs. The Site Geologist will review the core for the presence of fractures or

discoloration indicative of water. The Site Geologist will identify sample intervals in accordance with

SSFL SOP 26 (Attachment C) and immediately collect the sample. If there is any delay in core sample

collection, the core will be covered with a clear wrap to minimize the volatilization of VOCs. The rock

core will be photographed and logged in accordance with CDM Smith Technical SOP (TSOP) 3-5,

Lithologic Logging (Section 5.2.1, Lithologic Description of Discrete Soil or Rock Cores, included in

Attachment A). Logging information recorded will include the presence of fractures, lineaments, fine-

grained beds, lithology, weathering, and evidence of fluid flow. Core logs will be recorded on core log

forms included in Attachment B.

2.2 Core Sampling

Rock core samples will be selected upon review of the core, and collected as soon as possible after

retrieval and logging to minimize volatilization of VOCs. Sample intervals will be selected based on

fracture zones and intervals with elevated PID readings. Samples at fracture zones will be collected

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immediately above and below observed fractures, and will include fracture surfaces. If a fracture zone is

observed at the terminal depth of the boring, then the boring will be advanced an additional 5 feet to

facilitate sample collection of that fracture zone.

Sample collection, handling, and preservation procedures are detailed in Attachment C (SSFL SOP 26,

Bedrock Sampling).

Upon reaching the terminal depth of the boring (target depth is 60 feet below ground surface), air rotary

drilling methods will be used to ream the boring to a 6-inch diameter borehole. Each boring will be

completed as an open-bedrock borehole well with a locking well cap, stick-up completion, and well pad.

2.3 Downhole Geophysical Logging

Geophysical and video logging will be performed by a borehole geophysical subcontractor to locate

fracture zones, bedding planes, bedrock features, and presence of water. Geophysical logs will be

produced in accordance with the subcontractor’s (Colog) Technical Procedures (TPs).

Following is a list of geophysical logging tools that may be used:

▪ Single Point Resistance ▪ Induction ▪ Acoustical Televiewer ▪ Optical Televiewer ▪ Nuclear – natural gamma, gamma-gamma, and neutron ▪ Caliper ▪ Core dynamic fluid testing (CDFM)

The geophysical subcontractor will prepare a report that will include the finalized logs presented in

WellCAD® or similar format and an interpretation of results. The report may also include fracture tables,

rose plots, stereonets, and well summary plots, as appropriate.

2.4 Well Development

Based on water production experience with well RS-54, which is normally less than 0.5 gallons per day,

conventional development of the bedrock cores may not be possible. Water production in each of the

new wells will be monitored on a daily basis to check for water productivity. Any borehole producing

more than 2 feet water will be evacuated using a bailer prior and sampled following well recovery.

Boreholes not producing up to 2 feet of water will not be sampled. Water quality measurements will be

collected during development and sampling activities.

3.0 SAMPLE ANALYSIS

EMAX Laboratories, Inc. of Torrance, CA will perform the methanol extraction of the rock core samples

and analysis for VOCs by Method 8260. EMAX will also be used to analyze water samples for VOCs,

metals, and perchlorate.

4.0 QUALITY ASSURANCE/QUALITY CONTROL

No field QC samples (i.e., duplicate samples) will be collected of bedrock cores. Laboratory QC samples

will include calibration checks and other applicable method QC samples, as appropriate to the analytical

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method. Groundwater sample QC will be based on the SSFL Water Quality Sampling and Analysis Plan

requirements.

5.0 SCHEDULE

Drilling activities are anticipated to begin the week of April 30, 2018, and take 2 weeks to complete. 6.0

REPORTING

A Technical Memorandum will be developed to present results of the rock core samples and geophysical

logging.

FIGURES AND ATTACHMENTS

Figure 1 FSDF Core Hole/Open Bedrock Well Locations

Attachment A Technical SOP (TSOP) 3-5, Lithologic Logging

Attachment B Core Log Forms

Attachment C SSFL SOP 26, Bedrock Sampling

FIGURE 1Locations of Near-Surface Bedrock Core Holes, Former Sodium Disposal Facility

Old Alluvium- Old alluvium, rounded gravesl and cobbles in narrow deposit, moderately well cemented.

Coarse Grained Sandstone- Coarse grained sandstone to conglomeratic sandstone beds within the Chatsworth Formation, 3 inches to 1.5 feet thick.

Shale-Shale or siltstone beds within the Chatsworth Formation: are 3 inches to 1.5 feet thick, fissile to thin bedded with bedding present at 1 inch or less. Bedding planes typically show moderate to heavy iron oxide staining.

Fracture-Fracture, or joint: Appearance varies from strong, well defined lineament to faint, thin (1/8") black to dark brown lines of discoloration. Some features exhibit clay, CaCO3 or iron oxide filling, staining and/or halos. Some features are up to 1.5" thick.

PZ-099

LowerFSDFPond

UpperFSDFPond

L5

A9

AA9AA8

A8A7

A6

A5A4B4 B5 B6 B7 B8 B9

C8C7C6C5

C4

D4

D5 D6D7 D8

M10M9

M8M7M6M5M4M3M2M1M0

K1'K0 K1 K2

K3

K4

K5

K6K7 K8

K9

L9L8L7L6L2L1

L0

J0J1 J2

J3

J4J5 J6

J7J8

I9

I8

I7

I6I5

I4

I3I2I1

I0

H0H1

H3

H4

H5

H6 H7 H8 H9

G7G6G5G3G2G1

G0F1

F3

F4 F5F6

F7E8E7

E6

E4E3

E5

F8

F2

G4G8H2

J9L3 L4

D3

PZ-100

PZ-101RD-21

RD-54A

RD-54B

RD-64

C-08

RD-54C

RD-23

RS-54

SSG-10

SSG-11

SSG-7SSG-8

SSG-3SSG-13

SSG-1

SSG-12

SSG-2

SSG-4

SSG-5

SSG-14SSG-6

SSG-9

4

1 2

3

56

78

TCE: 570

TCE: 620TCE: 23

TCE: 680

TCE: 170TCE: 130

TCE: 71

TCE: 6.2J

TCE: 140

TCE: 6.8JTCE: 48TCE: 13U

TCE: 280TCE: 32

TCE: 240TCE: 66

TCE: 15U

TCE: 15U

TCE: 3900

TCE: 670

1,1,1-TCA: 23U

1,1,1-TCA: 5201,1,1-TCA: 24J

1,1,1-TCA: 1500

1,1,1-TCA: 56U1,1,1-TCA: 54U

1,1,1-TCA: 55U

1,1,1-TCA: 17U

1,1,1-TCA: 23U

1,1,1-TCA: 23U1,1,1-TCA: 17U1,1,1-TCA: 23U

1,1,1-TCA: 23U1,1,1-TCA: 43

1,1,1-TCA: 26U1,1,1-TCA: 35U

1,1,1-TCA: 30

1,1,1-TCA: 26U

1,1,1-TCA: 17000

1,1,1-TCA: 410

H St

C:\_projects\SantaSusana\GIS\MXD\Groundwater\GWIM\SSFL_GWIM_FSDF_Pond_111TCA_TCE_Results_wFractures_20180327.mxd 3/27/2018

Notes:- Original GIS layers provided by MWH/Boeing; updated by CDM Smith as needed.

- 1,1,1-TCA = 1,1,1-Trichloroethane.- TCE = Trichloroethene.- All results ug/m3.- J = Estimated result.- U = Non-detected result.

0 7035Feet

Service Layer Credits: - Aerial Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX,Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community.- Road Centerline Source: Esri, TomTom.

LEGENDFSDF MIP/Well LocationAbandoned Well/PiezometerCorehole LocationSSG Location

Former Concrete PoolRoad CenterlineCoarse grained Sandstone BedFracture

Iron oxide halos along fault/jointOld AlluviumShale or siltstone bedFormer FSDF Pond

Existing StructureDemolished StructureSSFL Property BoundaryArea IV Boundary

FSP Attachment C

Technical Standard Operating Procedures Page 1 of 5 © 2012CDM Federal Programs Corporation All Rights Reserved

Bedrock Sampling SSFL SOP 26 Revision: 0 Date: April 2018

Prepared: C. Zakowski Technical Review: Dung Nguyen

QA Review: J. Oxford Approved and Issued: April 2018

Signature/Date

1.0 Objective The purpose of this technical standard operating procedure (SOP) is to define the general techniques and requirements for the collection of rock core samples at the Santa Susana Field Laboratory (SSFL) site.

2.0 Background 2.1 Definitions Core Sample - A discrete portion of cylindrical core of rock obtained by rotating a hollow steel tube (core barrel) equipped with a coring bit at a designated location.

2.2 Associated Procedures 1. SSFL SOP 6, Field Measurement of Total Organic Vapors2. SSFL SOP 7, Field Measurement of Residual Radiation3. SSFL SOP 8, Field Data Collection Documents, Content, and Control4. SSFL SOP 9, Lithologic Logging5. SSFL SOP 10, Sample Custody6. SSFL SOP 11, Packaging and Shipping Environmental Samples7. SSFL SOP 12, Field Equipment Decontamination8. SSFL SOP 13, Guide to Handling Investigation Derived Waste9. SSFL SOP 15, Photographic Documentation of Field Activities10. SSFL SOP 16, Control of Measurement and Test Equipment

2.3 Discussion Rock core sampling and volatile organic analyses (VOCs) analysis for specific locations will be performed in Area IV of SSFL in accordance with this SOP and applicable planning documents including the Field Sampling Plan (FSP) Addendum (April 11, 2018).

3.0 General Responsibilities Field Team Leader - The field team leader (FTL) is responsible for ensuring that field personnel collect core samples in accordance with the FSP Addendum and this SOP.

Driller – The person responsible for collection of core sample.

Site Geologist – The person responsible for reviewing and logging the core samples.

Geologist Helper – The person assisting in recording logging information and preparation of samples for shipment.

Site Health and Safety Technician – The person who will use field screening instruments to monitor all field activities for VOCs and for scanning for radiological contaminants prior to shipment of sample coolers. This person is a trained radiological technician who works under the guidance of the Leidos Certified Health Physicist (CHP).

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4.0 Required Equipment at the Sampling Location ▪ Site-specific plans (including FSP Addendum, health and

safety plan, and all SOPs)▪ Monitoring/screening instruments required by health and

safety plan

▪ Insulated cooler ▪ Nitrile or other appropriate protective gloves

▪ Plastic zip-top bags ▪ Field logbook

FSP Attachment C



▪ Personal protective clothing and equipment ▪ Indelible blue or black ink pen and/or marker

▪ Drill Rig ▪ Decontamination supplies

▪ Core Barrel System

▪ Tape measure or other device graduated in tenths andhundredths of a foot

▪ Paper towels

▪ Sample labels

▪ 2-way radios

▪ Securely-sealed bags of ice ▪ Boring logs

▪ Aluminum Foil ▪ Visqeen

▪ Tape

▪ Parafilm

▪ Pop up tent

▪ Mylar vacuum sealer bags

▪ Global Positioning System (GPS) unit ▪ Vacuum sealer

▪ Trash Bags

5.0 Procedures 5.1 Preparation The following steps must be followed when preparing for sample collection:

1. Review site-specific health and safety plan and FSP Addendum before initiating sampling activity.

2. Don the appropriate personal protective clothing as specified in the site-specific health and safety plan.

3. Locate borehole location(s) in accordance with the FSP Addendum and document pertinent information in the fieldlogbook (SSFL SOP 8). Collect sample at intervals as described in Section 5.2.

4. Decontaminate sampling tools used to break off sample of core from main core.

5. The Site Health and Safety Technician will perform contaminant screening using hand-held instruments at each samplelocation before sampling and after driller retrieves core. The core materials will be screened for VOC emissionsimmediately upon retrieval for each sample collected (SSFL SOPs 6 and 7). If levels are detected above health andsafety plan action levels (HASP page 8), work will be temporarily discontinued, the Department of Energy (DOE), TheBoeing Company (Boeing), and the California Department of Toxic Substances Control (DTSC) will be contacted. Sitework will not resume at that location until further guidance is provided by DOE or Boeing. Contact information is in thehealth and safety plan.

5.2 Rock Sampling Procedure

Sampling procedures for consolidated material (e.g., bedrock) shall be executed in general accordance with ASTM D2113-08, Standard Practice for Rock Core Drilling and Sampling of Rock for Site Investigation. For the FSDF source investigation, a six-inch-diameter surface casing will be installed through overburden and approximately 2 to 4 feet into bedrock and grouted in place. Once the grout has been allowed to cure for a minimum of 12 hours, a HQ-sized (2.5-inch diameter) rock core boring will be advanced at 5-foot intervals using wireline rock coring methods to retrieve core samples. Immediately upon retrieval from the core barrel, each rock core will be placed in aluminum foil-lined tray and scanned with a PID. Should there be a delay in sample collection, the core will be covered with parafilm to minimize the volatilization of VOCs. Otherwise, the Geologist Helper will assist the Site Geologist in collection of core rock sample as described in Part 5.3 of this SOP. The Geologist Helper will assist the Site Geologist in describing the core, collecting photographs, and completing the log for rock quality designation (RQD), including the presence of fractures, lineaments, fine-grained beds, lithology, weathering, and evidence of fluid flow in accordance with SSFL SOP 9. Core logs will be recorded on boring log forms. Given that the FSDF investigation involves identified VOCs in near surface bedrock, the target depth of the FSDF will be 60 feet. The Geologist Helper will record sample identifier, date, and iii on the sample label.

Rock core samples will be selected upon review of the core. The sample will be collected as soon as possible after retrieval and visual inspection to minimize volatilization of VOCs. Sample intervals will be selected based on observed fracture zones and/or intervals producing elevated PID readings. Samples at fracture zones will be collected immediately

FSP Attachment C



above and below observed fractures, and will include fracture surfaces. If a fracture zone is observed at the terminal depth of the boring, then the boring will be advanced an additional 5 feet to facilitate sample collection of that fracture zone.

The sample description and collection information is recorded the boring log and in the field log book. A specific protocol on the collection of rock core samples for laboratory analysis of VOCs and physical parameters has been developed by the ASTM and is formalized in their standard ASTM D 5079, Rock Core Sample Preservation and Transport.

Sample preparation, preservation and transport of consolidated materials shall be executed in general accordance with ASTM D5079-08, Standard Practices for Preserving and Transporting Rock Core Samples. Specific steps are provided below.

Upon reaching the terminal depth of the boring, air rotary drilling methods will be used to ream the boring to a 6-inch diameter borehole. Each boring will be completed as an open-bedrock borehole well with a locking well cap, stick-up completion, and well pad.

5.3 Sample Collection The following general steps must be followed when collecting core samples.

1. Wear new, clean gloves during handling of all sample containers and sampling devices. Change out gloves at eachsampling location, or each time a new sample is to be collected, to avoid cross-contamination.

2. Document the sampling process by recording applicable information in the designated field logbook. Document anydeviation from the SOPs and the sampling plan in the field logbook and include rationale for changes. See SSFL SOP 8for guidance on entering information into field log books.

3. All downhole equipment must be decontaminated prior to drilling and between boreholes

4. When collecting rock cores for VOC analysis, it is necessary to minimize sample disturbance and consequently minimizeanalyte loss.

5. After the core sampler is removed from the borehole and opened by the driller’s helper, the core will be turned over tothe field personnel.

6. The core is placed on the core table and out of direct sunlight for visual logging and assessment.

7. The entire length of core will be scanned using a PID (or equivalent organic vapor monitor) to check for VOCemissions. Portions of the core indicating PID readings and/or indicative of fractured zones will be identified for samplecollection for laboratory VOC extraction and analysis. In the absence of PID readings or fracture zones, no sample willbe collected.

8. In addition to samples exhibiting elevated screening PID results and/or indicative of natural fractures, a control sample willbe collected at non-fractured intervals with no PID readings. The control sample is to serve as a “blank” sample foranalytical control. Control samples will be collected at a rate of approximately 10% of total samples. These samples willbe processed similarly to those collected within the fractured zones.

9. Samples to be submitted to the laboratory will be processed using the following procedures:- Cores will be kept out of direct sunlight and covered with parafilm prior to sample collection should any delay occur in

removing the sample interval.

- Samples will be selected based on criteria discussed in Section 5.2 and removed from the core. A chisel and

hammer will be used to break the sample free of the core with minimal disturbance to the selected sample increment.

- Rock core samples no greater than 4 inches in length will be broken from the core and immediately transferred into a

pre-labelled vacuum-sealable Mylar bag, approximately 7-millimeter thick. The open edges of the Mylar bag will beclean prior to insertion of the sample.

- A vacuum sealer will be used to remove air and seal the bag immediately after the sample is inserted.

-The sample label will contain the sample identifier, project name, date/time of collection, coring location ID, samplingdepth interval, and the initials of the samplers.

FSP Attachment C



- Following sealing, the samples will be placed in a cooler containing ice to cool sample to 4°. It is anticipated thatsamples will be picked up by a courier and delivered to the contracted laboratory on the same day.

10. The rock encountered in the coring will be logged as described in the SOP 9 Rock Core Logging. The Geologist Helpershould record bedrock descriptions including the rock type, color, weathering, fracturing, competency, mineralogy, andany other core characteristics described by the Site Geologist.

11. Following logging, the core shall be placed in a core box and labeled as to boring number and depth interval.

12. The sample identifier, location, depth, date and time will be recorded on the boring log and in the field logbook.

13. Relevant sample information will be documented in the logbook as well as in the laboratory-provided chain of custody.14. All non-disposable sampling equipment will be decontaminated in accordance with SSFL SOP 12.

Laboratory Sample PreparationUpon receipt at the contracted laboratory, samples will be extracted with methanol and subsequently analyzed using the following procedures:

- Remove the rock core sampling from its protective packaging. [Note, the size of rocks can’t be larger than 4-inch x 4-inch.]

- Crush the rock core into fragments. Store the remaining rock core sample in its original packaging for future use ifneeded.

- Reduce the size of the rock core sample using a rock crusher or other suitable milling device that will allow the sampleto pass through a 9.5 mm (0.375 inches) standard sieve.

- Weigh out 10 g of the processed rock core sample and transfer to a labeled 40 mL VOA vial. Record weight to thenearest 0.1 g.

- Add 10 mL of P&T Grade Methanol to the VOA vial and cap.

- Allow the sample constituents to come into equilibrium with the methanol by storing the VOA vial at <6ºC in the dark fora five-week period, with periodic shaking of sample once every week.

- Once the equilibration period is completed, analyze the methanol extract as specified by Method SW5035/8260B.

Laboratory Decontamination Procedure Prior to processing any samples, and between each new sample that is processed, the laboratory will perform the following steps to mitigate contamination:

- All laboratory materials used in sample crushing that come in contact with the core sample shall be coated in multiplelayers of aluminum foil.

- After processing each sample, discard all aluminum foil on the parts that come in contact with the sample.

- Prior to crushing of the next sample, apply new unused aluminum foil on all materials that come in contact with thesample.

Storage Blanks Due to the extensive amount of time that is required to allow for equilibrium of the sample with the methanol reagent, a storage blank is required to monitor any possible contamination of the sample from other sources. Storage blanks will be prepared as follows:

- Prepare one storage blank for each batch of rock core samples that are prepared and for each set of rock core samplesreceived, whichever is more frequent

- Storage blank is prepared by adding 10 mL methanol in a 40-mL VOA Vial.

- The storage blank samples will remain with the associated set of samples throughout the five-week equilibration period,and will be analyzed along with the samples at the end of the period.

FSP Attachment C



5.4 Boring Abandonment If borehole abandonment is required, the following procedures will be followed.

Borings will be abandoned as per the California Department of Water Resources’ California Well Standards, Bulletin 74-90 (January 1990). A cement-bentonite grout will be pumped starting at the bottom of the borehole through a tremie pipe. Shallow and dry holes less than 10 feet deep can be filled with grout or bentonite chips poured from the surface. The grout should be completed to 2 feet below ground surface and the borehole completed to the surface with the same native surface material as the surrounding area.

The grout will consist of clean water mixed with Type I or II Portland cement (or equivalent). It is also recommended that the grout include bentonite (3 to 5 percent by weight) to help reduce shrinkage. After the grout has set at least 12 hours, the grout will be topped off if settlement has occurred.

Close attention should be paid to the mixture of the grout that is placed into the borehole. The recommended mixture consists of one sack (94 pounds) of dry Portland cement mixed with 7.2 to 8.5 gallons of clean water and 3 to 5 percent of dry bentonite. The bentonite will be pre-hydrated if possible. Less water is required for a neat cement grout. The optimum mix results in a volume of 1.5 to 1.6 cubic feet of slurry per sack of cement. The grout will be mixed to a smooth, uniform consistency with no lumps or balls present.

If the surface required concrete or asphalt coring then the concrete or asphalt cores are to be replaced immediately following the completion of the borings (or at a minimum on the same day). Field crews will be responsible for patching or resurfacing the sample location back to previous conditions prior to leaving the sample location.

6.0 Restrictions/Limitations Before conducting the core sampling at each location, underground utilities and structures must be demarcated on the ground surface. In addition, archeological and cultural resources as well as Native American cultural concerns must be cleared. A subcontractor will be used to locate and mark the utility lines. The selected sampling location shall be a safe distance from the demarcated utility. In some cases, records regarding utility locations may not exist.

7.0 References U.S. Department of Energy. 1996. Hazardous Waste Remedial Actions Program. Quality Control Requirements for Field Methods, DOE/HWP-69/R2. September.

__________. Hazardous Waste Remedial Actions Program. Standard Operating Procedures for Site Characterizations, DOE/HWP-100/R1. September 1996 or current revision.

NASA RIWP Rock Core Sampling Revision 2.

ASTM International. 2008. D2113-08, Standard Practice for Rock Core Drilling and Sampling of Rock for Site Investigation.

ASTM International. 2008. D5079-08, Standard Practices for Preserving and Transporting Rock Samples.

California Department of Water Resources, California Well Standards, Bulletin 74-90 (Supplement to Bulletin 74-81), January 1990.