Seismic Refraction Surveys

Unexpectedly encountering rock during site development can be very costly to a well-balanced job budget. United Consulting utilizes the seismic refraction technique to assist our clients in avoiding this costly encounter by providing “up-front” information as to where rock and/or partially weathered rock may affect grading activities.

Applicability

Unexpectedly encountering rock during site development can be very costly to a well-balanced job budget. United Consulting utilizes the seismic refraction technique to assist our clients in avoiding this costly encounter by providing “up-front” information as to where rock and/or partially weathered rock may affect grading activities.

Design & Review of Blasting Programs

United Consulting is specialized in blast, noise, air overpressure and vibration consulting. We perform all data analysis and comparison in accordance with the standards and specifications as listed in the “Georgia Standard Blasting Act” and applicable United States Bureau of Mines publications and bulletins.

Two different types of instruments are available for this work. An Instantel DS-477 system and Thomas Instruments VMS 400 seismographs are utilized for our studies. Both types of instruments have capabilities for long term monitoring in the continuous strip chart mode and single event modes. This allows flexibility for monitoring of blasting, pile driving or heavy construction and compaction operations where vibration levels are of concern. The DS-477 system allows for extensive vibration analysis utilizing the 467/567-software package and both instruments provide the USBM RI8507 and OSMRE analysis plot after each event.

Pre and Post Construction Structural Surveys

Our professional engineers and geologists have extensive experience in performing pre-construction structural condition surveys. We are aware of the areas most likely to exhibit damage from blast and vibration activities.

During a pre-construction survey we examine the exterior and interior portions of a structure to note existing flaws. Hand written notes are made of all noticed defects and photographs of selected defects are recorded utilizing digital cameras. The digital photographs allow for long-term storage and easy incorporation into reports and documents. Our in-house structural engineers are also available to review any structural defects that may be considered hazardous. We also provide damage assessment evaluation for any claims made due to construction activities.

Geophysical Instrumentation

United Consulting is experienced in providing installation and monitoring of various types of geophysical/geotechnical instrumentation systems. These include inclinometers, settlement cells, load cells, strain gauges and monitoring wells. We also have the experience to perform down-hole surveys and logging utilizing electric, gamma, resistivity and cross-hole techniques.

Our surface geophysics capabilities are full range as well including the use of ground penetrating radar and magnetic and electromagnetic instruments.

• Inclinometers (Vertical and Horizontal)
• Piezometers
• Settlement Cells, Load Cells and Pressure Cells
• Soil Strainmeters
• Borehole Extensometers
• Strain Gauges
• Low Strain Integrity Testing

Probabilistic Seismic Hazard Analysis

• Seismic Coefficients; Aa and Av
• “S” Factor
• Performance Category Rating
• Soil Liquefaction Potential
• Site Shear Wave Velocity Values

Cathodic Protection Inspection

Corrosion is an electrochemical reaction based on universal laws of nature. All metallic structures corrode. It is just a question of how quickly.

Corrosion engineers determine the best technique to slow down or halt this process. Included in the techniques available are material selection, coatings, inhibitors and cathodic protection.

Cathodic Protection of structures such as pipelines, underground storage tanks, and water storage tanks is common. Facilities containing hazardous materials are governed by regulations that require periodic verification that the corrosion prevention system is working. Our NACE certified Cathodic Protection Tester can determine that your Cathodic Protection System is operating properly to protect your investment by periodically recording and interpreting the following data:

• Structure-to-electrolyte potential
• Rectifier voltage and current outputs
• Current output of galvanic anodes
• Magnitude and direction of current through mitigation bonds
• Resistance of groundbeds
• Integrity of rectifiers, isolating joints, electrical bonds
• other physical features associated with the corrosion control system

Our inspector is certified and experienced from a variety of technical disciplines including: structural engineering, cathodic protection, construction inspection, and bridge inspections. We also have a vast array of laboratory and field testing equipment. All of United Consulting’s testing equipment is calibrated on a routine basis in accordance with both national and international standards, and is ready to be put to use at a moment’s notice.

Electrical Resistivity Imaging

United Consulting has used Electrical Resistivity Imaging (ERI) to further explore the subsurface conditions at project sites in the southeastern United States in areas that are underlain by Karst geology.  Electrical Resistivity Imaging (ERI) is a technique used to map the resistance to electrical flow in the ground at varying depths and lateral locations.  Electrical current is introduced into the earth by two transmitting electrodes.  The apparent resistivity of the subsurface is obtained by measuring the drop in potential between the transmitting and receiving electrodes along the test alignment.  The depth of investigation is proportional to the separations between the transmitting and receiving electrodes.  Additionally, the size and detail of the features depicted in the inverted resistivity cross section is based on the distance between each electrode.  The electrodes must be spaced a minimum of 3 feet apart but can be spread up to 33 feet apart.  By varying this separation, as well as the separations between the two transmitting and the two receiving electrodes, different depths and locations along the line can be sampled to develop an apparent resistivity profile of the subsurface.

United Consulting utilizes an Advanced Geosciences, Inc. SuperSting-R8 IP resistivity system.  The SuperSting-R8 IP is a multi-channel portable memory earth resistivity meter that incorporates the resistivity meter and data logger, while the unit configures and switches the various electrodes used during the data acquisition process.  The data collection process begins by hammering 18 inch metal rods into the subsurface soils at the measured electrode locations.  The Multi-channel Swift Duel Mode Automatic Multi-electrode cables are then laid out, the electrodes are attached to the rods and the survey is performed.  The SuperSting-R8 IP is utilized in the field by attaching the cables to a switch box which allows for the use of multiple cables of various electrode spread lengths.  The field flexibility of this instruments configuration allows for data collection on both small and large sites with varying depth and detail based on the client’s needs.