STRATIGRAPHICS specializes in penetrometer exploration services for geo-environmental and geotechnical studies. The penetrometer method is minimally intrusive, using a high capacity hydraulic ram mounted on a heavy truck to push small, 1.7 inch diameter probes directly into the ground, without drilling a borehole. Electronic sensors mounted inside the probe, called a penetrometer, provide a continuous record of the response of the soil to penetration. Computerized display and recording of data allow immediate evaluation of subsurface conditions.

Penetrometer data are used for the indirect interpretation of site geotechnical, hydrogeological, and qualitative geochemical characteristics. Well documented and widely accepted techniques allow rapid, high resolution (1 inch) definition of the vertical extent of aquifer and aquitard strata. Superior evaluation of the lateral continuity of layers is routine with penetrometer data. The measurement of water tables, potentiometric surfaces in confined aquifers, and soil hydraulic conductivity is quickly performed. Soil electrical conductivity anomalies, possibly associated with LNAPL or DNAPL contaminants, and landfill leachate or brine intrusion, are readily identified.

In addition to penetrometers with sensors, penetrometer samplers are used to sample groundwater, soil and soil gas for use in analytical testing. Direct samples confirming indirect measurements are quickly, reliably and economically obtained. Penetrometer installation of wellpoints and piezometers is performed for longer term monitoring purposes.

Penetrometer testing is much more economical and quite often more accurate than borehole drilling and sampling because of high productivity and electronic data acquisition. Over 900 feet of geotechnical penetrometer soundings have been performed in one day. Groundwater sampling is also efficiently performed with as many as 12 samples acquired in one day.

Penetrometer data are acquired without drilling a borehole. The lack of a large diameter borehole and the lack of drill cuttings not only minimizes expensive hazardous waste disposal costs, but also lessens contact of field personnel with contaminated soils. It is unusual for penetrometer exploration to be performed in any safety level other than Level D. The penetrometer rod string is decontaminated during retrieval, before personnel come into contact with any downhole equipment. The small hole left after penetrometer testing is pressure grouted to control cross-contamination.

A specially designed, 3 axle truck is used to house, transport and deploy the STRATIGRAPHICS penetrometer system. The rig's 23 ton ballasted weight resists the thrust of the hydraulic ram. Penetrometer sounding depths deeper than 100 feet can be achieved at many sites. Very dense soils with SPT blowcounts of more than of 100 blows/foot can be explored using penetrometer methods.

Site characterization including contaminant plume delineation can be accurately performed using rapid penetrometer methods. Permanent groundwater monitoring wells can then be economically installed at optimal locations using a minimum of expensive borehole drilling. The combination of minimally intrusive penetrometer methods and large diameter borehole drilling is less expensive and less disruptive to site activities than use of drilling methods alone.

Penetrometer data are used directly for geotechnical design of pile foundations. Data are also used to evaluate soil drained and undrained shear strength for slope and excavation stability, relative density for ground improvement projects, and compressibility and pre-consolidation pressures for settlement analyses. Soil liquefaction analyses are also performed using penetrometer data.

PENETROMETER ELECTRONIC DATA ACQUISITION FOR
GEO-ENVIRONMENTAL AND GEOTECHNICAL STUDIES

Electronic penetrometers have been used for soil exploration since the early 1960's. Penetrometer testing is routinely specified for many geotechnical studies and is well documented in the literature. A penetrometer was even used by NASA for geotechnical characterization of the lunar surface during the Apollo space program. Penetrometer use is becoming common in geo-environmental studies. Significant research into penetrometer sensor technology for downhole contaminant analysis is being conducted by the Departments of Defense and Energy. STRATIGRAPHICS has been developing penetrometer equipment and providing exploration services for geo-environmental and geotechnical studies since 1987.

The Cone Penetration Test (CPT) consists of pushing an instrumented penetrometer into the ground at a constant rate of 4 feet per minute, while continuously measuring the resistance of the soil to penetration (ASTM 5778 and D6067). The end bearing resistance on the conical tip and soil friction along the sides of the penetrometer are simultaneously measured during the test. The CPT cone end bearing resistance is very sensitive to grain size. For example, the cone end bearing is one to two orders of magnitude higher in a medium dense sand aquifer than in a stiff clay aquitard. The ratio of friction to cone end bearing resistance (termed friction ratio) is also indicative of the fines content of the soil. The CPT friction ratio is high in clays and low in sands. Computerized CPT soil type classification charts are used in identifying site stratigraphy. Various geotechnical parameters, in addition to soil types, can be derived from CPT resistance measurements.

Piezometric CPT (CPTU) consists of continuously measuring the CPT soil resistance measurements and pore-water pressure response to penetration, to obtain both geotechnical and hydrogeological information. The CPTU piezometric measurements allow for rapid evaluation of soil saturation, water tables, potentiometric surfaces in confined aquifers, and soil hydraulic conductivity and consolidation characteristics.

Piezometric Cone Penetration Tests with soil Electrical Conductivity measurements (CPTU-EC) provide simultaneous measurements allowing geotechnical, hydrogeological and qualitative geochemical evaluation of site characteristics. Soil electrical conductivity and temperature are continuously measured using a high resolution (1 inch) electrode array and thermal sensor mounted on the penetrometer. Soil electrical conductivity depends primarily on the soil pore fluids and soil clay content. Unsaturated soils and soils saturated with many LNAPL and DNAPL compounds exhibit very low electrical conductivity. Dissolved inorganic compounds, such as those contained in brines and landfill leachates, significantly increase soil conductivity.

The CPT, CPTU and CPTU-EC graphical data presentations (sounding logs) are produced immediately as the penetrometer test progresses. Layering and saturation are visibly obvious, as are relative strength and consistency. Soil EC anomalies, possibly associated with contamination, are also obvious. A series of penetrometer sounding logs can be used to characterize subsurface site conditions with ease and accuracy.

PENETROMETER GROUNDWATER, SOIL AND SOIL GAS SAMPLING

Penetrometer samplers, designed by STRATIGRAPHICS specifically for high capacity penetrometer deployment, are available for groundwater, soil and soil gas sampling. Penetrometer sampling offers great advantages for environmental studies, as the method is minimally intrusive. Penetrometer methods are also rapid, economical, and highly accurate. No drill cuttings requiring expensive disposal are generated during penetrometer operations. Exposure of personnel to contaminants is much less than during drilling operations.

Groundwater Sampling The STRATIGRAPHICS groundwater sampler is a shielded wellpoint sampler, somewhat similar in operation to the Hydropunch 1 (tm). The sampler is deployed with the shield closed to avoid contamination and clogging of the sampler screen. The shield is retracted at the desired sampling depth, allowing groundwater to flow through a 20 inch long screen into the sampler. The rate of sample inflow can be electronically recorded, allowing evaluation of soil hydraulic conductivity. The sampler is then retrieved to decant as much as 320 ml of sample, enough to fill multiple VOA vials. An inertial pump can be used to acquire larger sample volumes as might be required for semi-volatile or inorganic analyses.

The STRATIGRAPHICS sampler is much more robust and simpler to operate than commercially available samplers. This allows greater depth capabilities and more reliability. We have been using this sampler since 1991 to the satisfaction of our clients and federal agencies, such as the EPA and Corps of Engineers. We carry multiple STRATIGRAPHICS samplers on the rig for efficient operations. As many as 12 penetrometer groundwater samples have been acquired in one day.

Soil Gas Sampling The STRATIGRAPHICS soil gas sampler is a shielded sampler with a short slide assembly. The shield is retracted at the desired sampling depth, opening the sampler and rod string to the soil. Tubing is sealed to the rod string, and a suction is applied to extract gasses from the soil. Vacuum pressures are recorded, allowing evaluation of soil vapor permeability. Soil gas is then conducted to either analytical equipment or storage bags. The sampler slide may then be closed, allowing subsequent samples to be obtained without tripping the rod string.

Soil Sampling STRATIGRAPHICS uses a fixed piston soil sampler. The sampler is pushed into the ground with the piston locked at the tip of the barrel, preventing premature entry of soil into the sampler. The piston is unlocked and held stationary at the desired sampling depth using a wireline tool. The rod string and sample barrel are then advanced, forcing soil to enter the sampler. A core catcher can be used to improve sample recovery. The sampler is retrieved to extract the soil and is then decontaminated. Liners can be used to lessen personnel contact with contaminants.

Piezometer Installation Piezometers and other instrumentation packages can be set using penetrometer methods. Nominal 3/4 or 1 inch PVC piezometers are placed inside a larger diameter steel casing pushed to depth. The casing is sealed with a sacrificial tip, which prevents soil from entering the casing. The PVC filter fabric wrapped screen and threaded risers are lowered after the casing has been pushed to the required depth. The casing is then withdrawn, leaving the tip and piezometer in place. A bentonite seal may be placed to isolate the well screen.

Steel wellpoints also can be installed using penetrometer methods by directly pushing pipe-base screen and flush joint risers into the ground. Wellpoint materials can be black iron, galvanized or stainless steel.

Grouting System The hole left after penetrometer testing is pressure grouted with the STRATIGRAPHICS simultaneous-with-sounding grouting system. Bentonite slurry is pumped into the small annular space between the penetrometer sounding rods and soil formed by passage of the slightly larger diameter penetrometer. A bypass valve is opened at the bottom of the hole to allow additional grout to be pumped into the hole as equipment is being retrieved, thus sealing the hole. About 1/2 gallon of grout is required to seal 10 feet of open hole.

In addition to sealing the small hole left after penetrometer retrieval, pumping of grout into the small annular space around the rod string also serves to control cross contamination as the hole is advanced. The grout can decrease downhole equipment contact with the surrounding soil, lessening exposure of personnel to contamination. The grout also can decrease soil friction on the rod string, allowing deeper penetration capabilities.

Equipment Decontamination All downhole equipment is pulled through a rod-washing, decontamination chamber. The chamber is mounted at the base of the hydraulic thrust cylinders. The rod string is steam cleaned as it passes through the chamber, before handling by field personnel. Rubber wipers at the entry and exit of the rod-washing chamber control water leakage and wipe soil and grout off the rod string. Wash water, in the amount of about 3/4 gallon per 10 feet of hole, can be captured and containerized. The steam cleaner, 200 gallon water tank and 5 kW diesel generator are all permanently mounted on the penetrometer truck, avoiding use of a support vehicle.

COMPANY BACKGROUND

STRATIGRAPHICS, the Geotechnical Data Acquisition Corporation, is a service company that has been providing high quality penetrometer exploration services to our clients since 1987. The company specializes only in penetrometer exploration. No consulting or drilling work is performed by STRATIGRAPHICS. A high capacity, 23 ton truck mounted penetrometer system, and portable equipment, is used to obtain penetrometer data and samples for geotechnical and geo-environmental investigations.

Penetrometer equipment is custom built by STRATIGRAPHICS, for our own use, to much higher standards than in most commercially available equipment. This allows use of penetrometer technology at more sites than has been previously possible. Needs of the geo-environmental market have been particularly well addressed by STRATIGRAPHICS. Use of automatic downhole equipment decontamination, pressure grouting, heavy duty samplers and Piezometric Cone Penetration Testing with soil Electrical Conductivity measurements (CPTU-EC) to provide real-time data has allowed our clients to more accurately and more economically characterize their sites. Our clients have also been most pleased by our policy of using highly experienced engineers to run the penetrometer rig on every project. This policy provides a great deal of technical expertise in the field during the critical data and sample gathering phase of a site characterization project.

Andrew Strutynsky, the Technical Director of STRATIGRAPHICS, has specialized in penetrometer system design and exploration since 1982. He has more than 500,000 feet of penetrometer experience gained in projects throughout the United States, Far East, Europe and off the polar ice cap. He has designed various penetrometer systems for unique projects and has published numerous articles on penetrometer technology and data interpretation. He has also conducted workshops on penetrometer techniques for the National Water Well Association, and was a speaker at the First International Symposium on Penetration Testing.

STRATIGRAPHICS is committed to providing data acquisition services of the highest quality to our commercial and government clients. Company experience, dedication and high productivity allow both routine and unusual projects to be successfully completed within time and budget constraints. A wide range of exploration problems can be solved by STRATIGRAPHICS through use of in-house design capabilities and manufacture of high quality, custom penetrometer systems.

PUBLICATIONS

Strutynsky, A.I., R. Sandiford, and D. Cavaliere, 1991, "Use of Piezometric Cone Penetration Testing with Electrical Conductivity Measurement (CPTU-EC) for Detection of Hydrocarbon Contamination in Saturated Granular Soils," ASTM, San Diego, CA.

Strutynsky, A.I. and T. Sainey, 1990, "Use of Piezometric Cone Penetration Testing and Penetrometer Groundwater Sampling for Volatile Organic Contaminant Plume Detection," NWWA, Houston, TX.

Saines, M., A. Strutynsky, and G. Lytwynyshyn, 1989, "Use of Piezometric Cone Penetration Tests in Hydrogeologic Investigation," First US-USSR Conference on Hydrogeology, Moscow, USSR.

Strutynsky, A.I., B. Douglas, et al., 1985, "Arctic Penetration Test Systems," Civil Engineering in the Arctic Offshore, ASCE, Fairbanks, AK.

Douglas, B.J., A. Strutynsky, et al., 1985, "Soil Strength Determinations from the Cone Penetrometer Test," Civil Engineering in the Arctic Offshore, ASCE, Fairbanks, AK.

Mahar, L.J., B. Douglas, A. Strutynsky, et al., 1985, "Rapid Deployment System: A Method for Conducting In Situ Soil Tests from Moving Ice in the Arctic Offshore," Civil Engineering in the Arctic Offshore, ASCE, Fairbanks, AK.

Douglas, B.J., A. Strutynsky, and S. Brown, 1984, "In Situ Testing II, People's Republic of China," Report to the National Science Foundation, Grant No. CEE 8311873.

Douglas, B.J. and A. Strutynsky, 1984, "Cone Penetrometer Test, Pore Pressure Measurements and SPT Hammer Energy Calibration for Liquefaction Hazard Assessment," Report to the USGS, Earthquake Hazards Reduction Program Contract No 14-08-0002-19105.

Petersen, F.S., K. Kasper, T. Francoeur, and A. Strutynsky, 1993, "Using Innovative Sample Collection and Field Analytical Techniques to Rapidly Characterize Multiple Petroleum Hydrocarbon Sites," SPE/EPA, San Antonio, TX.

PRESENTATIONS

"Introduction to Electronic Cone and Piezocone Penetration Testing," workshop conducted by A.I. Strutynsky at the Third National Outdoor Action Conference on Aquifer Restoration, Groundwater Monitoring, and Geophysical Methods, NWWA, 1989.

"Stress History and Normalized Soil Behavior from CPT" presented by A.I. Strutynsky at the First International Symposium on Penetration Testing, 1988.

"Use of Penetrometer Techniques for Geo-Environmental Studies," C.R. Strutynsky and A. Strutynsky, poster session, Association of Engineering Geologists Annual Conference, 1991.

SELECTED PROJECT REFERENCES

Dow Ludington, Michigan Plant. Piezometric Cone Penetration Test with soil Electrical Conductivity measurement (CPTU-EC) soundings, groundwater and soil sampling, and piezometer installation. Client: Dow Chemical USA.

Proposed Atlantic City Convention Center, Atlantic City, New Jersey. Piezometric Cone Penetration Test (CPTU) soundings. Client: Dames and Moore.

Parker-Hannifin Site, Waverly, Ohio. Piezometric Cone Penetration Test (CPTU) soundings and groundwater sampling. Client: ERM Midwest.

JFK International Airport. Piezometric Cone Penetration Test with soil Electrical Conductivity measurement (CPTU-EC) soundings. Client: Port Authority of New York and New Jersey.

ARCO East Hartsdale Pipeline. Piezometric Cone Penetration Test with soil Electrical Conductivity measurement (CPTU-EC) soundings, groundwater and soil sampling, and piezometer installation. Clients: ABB-ES and ARCO Pipeline Company.

Superfund Sites (Operating Units 5 and 6), Hill Air Force Base, Ogden, Utah. Piezometric Cone Penetration Test with soil Electrical Conductivity measurement (CPTU-EC) soundings, groundwater and soil gas sampling, and piezometer installation. Client: Radian Corporation.

Preliminary Assessment/Site Investigation, Wendover Air Force Base, Wendover, Utah. Piezometric Cone Penetration Test with soil Electrical Conductivity measurement (CPTU-EC) soundings, groundwater and soil gas sampling, and piezometer installation. Client: Radian Corporation.

317/319/ENE Landfill, Argonne National Laboratory (DOE), Argonne, Illinois. Piezometric Cone Penetration Test with soil Electrical Conductivity measurement (CPTU-EC) soundings, groundwater sampling, and piezometer installation. Client: Weston Corporation.

DeKalb County Landfill, DeKalb, Illinois. Piezometric Cone Penetration Test with soil Electrical Conductivity measurement (CPTU-EC) soundings. Client: RUST EI Corporation.

Autumn Hills Landfill, Zeeland, Michigan. Piezometric Cone Penetration Test with soil Electrical Conductivity measurement (CPTU-EC) soundings. Client: Waste Management of Michigan.

General Motors - DELCO Plant, Vandalia, Ohio. Piezometric Cone Penetration Test with soil Electrical Conductivity measurement (CPTU-EC) soundings and groundwater sampling. Client: Earth Sciences, Inc.

Landfills 8 and 10, Wright-Paterson Air Force Base, Dayton, Ohio. Piezometric Cone Penetration Test with soil Electrical Conductivity measurements and groundwater sampling. Client: Engineering Science, Inc.