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Soil Mechanics Laboratories

National Design, Construction and Soil Mechanics CenterNatural Resources Conservation Service

Lincoln, NE Fort Worth, TX512 South 7

thSt. 501 W. Felix St., Bldg. 23

Lincoln, NE 68508 Fort Worth, TX 76115402-437-5337 817-509-3322

http://www.ndcsmc.nrcs.usda.gov/contact/directory/soil.html

NDCSMC Co-Director: Stephen D. Reinsch, Lincoln, NE

Fort Worth Lab Supervisory CE: Lee Ann Moore, Fort Worth, TX

Purpose: The Center laboratories provide engineering soil testing services and soil mechanicsrelated design recommendations to NRCS engineers in the 50 United States, PacificBasin and Puerto Rico for projects in various NRCS programs for over 40 years.

The Center consists of two laboratories. The two labs were originally established toprovide engineering soil testing, analyses, and reports for structures in the smallwatershed program, which were primarily dams. Today, the workload has expandedto include a large number of agricultural waste lagoon projects, EWP, andrehabilitation of watershed structures.

The labs perform a wide range of tests to determine various engineering (notagronomic) properties of soils. These tests provide site-specific information that is

not available in published soil surveys. Testing includes determination of thefollowing soil properties:

USCS soil classification (CL, CH, SC, GM, etc.)PermeabilityCompressibilityStrengthDispersionGrain size distribution / Filter requirementsCompaction propertiesPlasticityOthers

Engineers associated with the laboratories provide detailed geotechnical engineering analysis oncomplex structures based on test results. Typical analyses performed are soil stability, seepage,and settlement analysis. Analysis is also performed on low permeable soil liners for animalwaste systems.

The labs also provide technology transfer and soils engineering training to NRCS employees andmaintain testing data records and testing correlation data.

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GENERAL GUIDELINES FOR SUBMITTING SOILSAMPLES TO THE SOIL MECHANICS LABS

Undisturbed samples are usually submitted in cores or tubescollected by an investigating geologist.

Also, small shelby hand samplers are used to collect undisturbedsamples from constructed ag. waste liners. If you would like toborrow hand sampler to collect and send a sample forpermeability testing, please contact either of the labs.

Small disturbed samples are submitted tothe labs for determining index propertiessuch as natural water content, dispersion,specific gravity of soil particles and

Atterberg limits.

Large disturbed samples aresubmitted when more than justindex tests are needed.

Large samples are needed forcompaction tests, remoldedpermeability tests, and/orremolded shear tests.

For sample sizes needed,please see the following table.

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SAMPLE SIZES

DESCRIPTION OF LARGEST TYPE MINIMUMGRAVEL IN SIZE GRAVEL OF SAMPLESAMPLE IN SAMPLE SAMPLE SIZE (lbs)

Sample has less < 3/4 " "S" 2than 10 % gravel 3 " "S" 10

3 " "L" 50

Sample has over 3 " "S" 2010% but less than "L" 7550 % gravel

Sample has more 3 " "S" 40than 50 % gravel "L" 100

The size of sample you need to submit depends mainly on two things:

(1) What tests you are requesting, and

(2) The amount of gravel in the sample and the size of any gravel particles inthe sample.

If you are submitting samples only for index tests, gradation and Atterberg limits, youneed to send a sample size designated "S" in the previous table.

If you are requesting compaction testsand/or permeability tests, you should senda sample size designated "L" in theprevious table. The Soil Mechanics Labsoften receive samples that are too smallfor the requested tests to be performed. It

is not desirable to reuse soil for multiple

tests because the soil properties changewith each cycle of wetting and drying.

Large sample with nogravel for an ag. waste

storage pond.

Sam le

Scale

Scale

Readout

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You should submit a sample list with the sampleshipment. A blank sample list is attached and can becopied and used to submit with sample shipments.This is needed so the lab staff can check that allsamples listed are actually received and identified

clearly.

The Soil Mechanics labseach receive about 1,000samples per year, andaccurate tracking of samplesdepends on good writtendocumentation.

Methods for labeling and tagging samples forshipment to the Soil Mechanics Center arevery important. Using indelible ink on papertags and permanent ink on plastic bags aremethods of labeling samples that help insureeasy identification by the laboratories. Waxpencils and some markers (even permanentones) will rub off during shipment - even if thebags are packed in boxes. It is alwaysadvisable to have redundant labeling, with asample tag inside the bags with the soil as

well as having the outside of the bag labeled.

Include a copy of a letter or form 356 detailingthe tests requested, sample and siteidentification information including projectname, type of program (WF-08, CO-01, EWP,etc). Also include a name and address to

contact with any questions, and names and

addresses of those to receive a copy of thetest report with the shipped samples.

Copies of this information may also need to

be sent to your State Conservation Engineeror Resource Engineer.

Sample Listand Cover

Letter

Sample Listand Cover

Letter

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SAMPLE LIST FOR SOIL MECHANICS LABORATORY

STATE:_________________COUNTY: ________________________________________

SITE NAME: ______________________________________________________________

PROJECT TYPE:________________________FUND / PROGRAM: _____________________(repair, new dam, etc.) (WF-08, EWP, CO-01, etc.)

CONTACT PERSON: ____________________ PHONE: _______________________________

__________________________________ FAX: _____________________________

Laboratory

SampleNumber

Field

SampleNumber Description or Location

Depth,(feet)

Size ofSample

Testing Requested:

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Plastic buckets (5 gal. or larger) with sealable lids are ideal forcollecting and shipping samples. The sample may be eitherplaced directly in the bucket or inside a plastic bag in the

bucket. Used buckets (like from the food service industry orcleaned paintbuckets are fine aslong as they arecleaned and willseal.)

If buckets arent available, sturdy plastic bags should be

used for the samples. This prevents bag rupture andspillage during shipment. If thinner bags are used,double the bags. The samples in plastic bags may beshipped in sturdy corrugated paper boxes withreinforcement tape at the seams.

However, you should not use very thin bags and rely on the box to keep the sample intact.

Keep in mind that once the sample arrives in the lab,the bags or containers need to be sturdy enough to bemoved without bursting.

Bag is torn and soil is

loose and dried out.

The sample as it was

opened.

NO THIN

BAGS

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Even small disturbed samples may need to be double-bagged to prevent drying out and to insure that the sampleis intact upon arrival at the lab.

The natural water content can be a very important piece ofinformation. When submitting large samples on projectswhere the water content of the sample represents themoisture conditions expected during construction, it is agood idea to submit an additional small sample designatedfor the water content measurement.

Note: If you have questions about locating suitable containers or plastic bags forshipping samples, please feel free to call Lee Ann Moore in the Fort Worth SoilMechanics Lab at 817-509-3322.

Two bags

Sample labelbetween thebags. Keepsmoisture off thetag and keepslabel with thesam le.

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Where to Ship Samples

Large samples may be shipped to the Soil Mechanics Centers by normal truck freightlines. To ship large samples by US mail, FedEx, or UPS, you can split large samplesinto several smaller samples for shipment. Address samples to:

Soil Mechanics Laboratory or Soil Mechanics LaboratoryBuilding 23 512 South 7th StreetFort Worth Federal Center Lincoln, NE 68508501 Felix StreetFort Worth, TX 76115