Announcements
NORCAL celebrates 25th Anniversary in 2008
The year 2008 marks our 25th year of providing geophysical services. We are very proud of this milestone and we are even more eager for the next 25 years. During this time there have been monumental changes in the geophysical industry. These changes included the introduction of personal computers for data processing, instrumentation moving from analog to the digital age, significant improvement in computer software for both modeling and data presentation, and new methodologies that provide increased subsurface resolution. Consequently, geophysics is more routinely used with a higher level of confidence to stand alone or supplement other phases of an investigation. During the past 25 years we have seen the introduction of borehole televiewers for oriented 3D imaging of borehole walls, computer controlled switching for multi-electrode electrical resistivity profiling systems, analysis of seismic surface waves for the determination of shear wave velocities, 3D methods for seismic, electrical and ground penetrating radar, and increased accuracy of global positioning systems to name a few. Presently we are on the verge of wireless transmission of geophysical data. In the midst of all these technological advances, NORCAL has managed to stay at the fore front of new technology while at the same time providing “down to earth” answers and solutions for our clients.
NORCAL started in 1983 as a one office facility complete with an Apple IIe computer, an electronic typewriter, and a small storage space for equipment. In that office Ken Blom and Bill Black wore several hats while performing all of the duties required to run a business including data processing, report writing, graphics, accounting and clerical tasks. In 1984 we purchased our first seismograph and electrical resistivity system. By this time we had expanded to two separate offices and purchased our second computer complete with a dot-matix printer. By 1985 we were the proud owners of a new ground penetrating radar system and had hired our first employee. During 1985 to 1988 we further enhanced our geophysical equipment suite with a magnetometer, an electromagnetic conductivity EM-31 system and two more employees. In 1988 we moved to bigger and better office spaces with significantly larger warehouse space and added an office manager to our staff. For the next few years our work load increased significantly requiring the hiring of two additional geophysicists as well as the acquisition of more seismic and ground penetrating radar equipment. This was accompanied by constant upgrades in computer hardware and software. In 1994 NORCAL expanded its capabilities to include borehole logging and imaging instrumentation and by the hiring of Bill Henrich to manage this new department. Over the next few years our ever challenging projects required an increased usage of all terrain vehicles, electrical resistivity profiling, specialized seismic sources, and more sophisticated borehole logging equipment. Consequently our suite of field equipment increased even more. A noteable milestone occurred in 2004 when we designed and built a 6500 square foot building tailored to our office and warehouse needs. Presently we can offer a lengthy resume of experience, the best geophysical crew in the business, a full suite of field equipment, the latest in computer processing software, and the desire to get even better. Our sincere thanks to all of our clients that have put trust in our services. The next 25 years will be a great journey!
Recent Notable Projects
During the past year we have performed a variety of investigations that had unique objectives, were conducted in unusual conditions, or required demanding logistics to accomplish our goals. A few of these notable projects are as follows:
- Deep Seismic Reflection Survey at a quarry in Northern California to map possible stratigraphic traps in tertiary sediments faulted beneath granitic rock. The high resolution survey delineated sedimentary layers to depths in excess of 6,000-ft.
- On-going Vibration Monitoring at historic buildings in Sacramento, CA. This survey is being conducted to monitor ground vibration levels caused by nearby construction. Vibration monitors installed in two buildings are in their third year of 24-hour per day, 7-day per week operation. The data are automatically telemetered to our office and to the structural engineers office at predetermined times each day in order to monitor and archive ground vibration levels for future reference.
- On-going Very High Resolution Electrical Resistivity and Seismic Refraction surveys at the Idaho National Laboratory to determine the thickness of an engineered cap that covers radio-active waste and the depth to the underlying bedrock. This required the use of non-invasive method to characterize the subsurface conditions so that the hazardous waste would not be encountered during excavation activities.
- Towed Array MASW Survey to map subsurface conditions beneath the tarmac at the United States Coast Guard Station, San Francisco. A land streamer consisting of 24-geophones mounted to a tow-strap was towed along the tarmac by an ATV configured with an accelerated weight drop. The MASW survey delineated variations in the thickness of the fill underlying the tarmac.
- High Resolution GPR Survey to delineate voids beneath the slab of an airplane hangar at Anchorage International Airport. This survey had to be completed in a timely manner because of an on-going volcanic eruption in the Aleutian Islands. Had a change in wind direction carried the volcanic ash over Anchorage it would have been necessary to park the aircraft in the hangar to protect them. However, before this could be done it was necessary to inspect portions of the hangar floor to make sure they were not underlain by voids.
- Review and Reanalysis of Geophysical Data collected at a nuclear power plant site in Switzerland. NORCAL was contracted to review reports and reprocess selected data sets collected by three different Swiss geophysical companies at a nuclear power plant near Muhleberg, Switzerland.
- On-going High Resolution Electrical Resistivity Surveys to evaluate subsurface conditions beneath the toe of a levee on the Sacramento River.