A geophysical survey is an evaluation of the ground below the surface of a site. Using radar and electromagnetic technology, the survey provides a non-invasive way to find and identify any structures or other underground features that may shed light on the storage and use of hazardous materials.
Geophysical surveys are often included in a Phase 2 Environmental Site Assessment (ESA), which is a scientific test to determine whether contamination or hazardous materials are present below a property’s surface. This assessment follows a Phase 1 Environmental Site Assessment when recognizable environmental conditions are found on a property.
Geophysical surveys are often recommended and included in Phase 2 Environmental Site Assessments to help locate subsurface objects such as buried tanks or drums. The surveys are also used to identify underground utilities and suitable locations for soil borings and groundwater monitoring wells.
Interpreting the results of a geophysical survey requires specific knowledge and experience. That’s why Alpha Environmental always utilizes its staff of professional geologists and environmental scientists to help you understand the findings and develop a plan if concerns are discovered.
Geophysical Survey Uses
Whether you’re in the midst of a real estate transaction or are planning a construction site, identifying underground features allows for better planning and ultimately saves money and time. Aside from locating current underground structures, a geophysical survey can offer insight into hazardous materials that may have been present in the past based on leftover pipes and utility lines.
Full knowledge of the presence or absence of underground hazards can help buyers and lenders make better decisions before developing on the land. The information gained from a geophysical survey can also protect stakeholders from the costs and headaches associated with environmental liabilities that could become problematic down the road. Unaddressed environmental concerns can greatly decrease a property’s value.
Because of their non-invasive nature, geophysical surveys may be the most cost-effective or logistically viable method available to evaluate the subsurface features of a site. They have the ability to map out large areas of a property at once, providing massive amounts of data that typically aren’t available through traditional techniques. Methods such as drilling or excavating are often used to confirm the geophysical findings.
Depending on site conditions and the subsurface features that need locating, Alpha Environmental typically recommends ground-penetrating radar (GPR) and magnetic surveys to find and identify underground anomalies.
What is GPR?
Ground-penetrating radar is a technique used to capture images below the surface using radar pulses. Using a transmitter and receiver, GPR records echoes from subsurface objects. Variations in each echo are then used to extract insight into the object’s density, and signals are turned into images of objects and mapped using a specialized software.
The main benefit of GPR is that it’s performed in real-time, allowing experts to get an instant picture of storage tanks, utility lines or other underground objects without breaking ground.
What is a Magnetic Survey?
A magnetic survey uses a magnetometer to detect ferrous objects by measuring small variations in the earth’s magnetic field. Similar to GPR, it uses a digital receiver to measure and record magnetic information on a data logger. The data is processed in the field and a magnetic contour map is generated. Magnetic anomalies may be further investigated with varying types of small hand-held metal detectors or with GPR.
Magnetic surveys can provide information of large areas quicker than other geophysical methods and offer additional insight into the composition of the ground below the surface.
Contact a Professional
Alpha Environmental’s non-invasive geophysical surveys can be performed rapidly, with results often available the same day. Results are qualitative, meaning it takes an experienced professional to properly interpret them. That’s why it’s important to hire a trusted expert who can offer accurate information about any existing environmental risks.
Contact us today to learn more about our geophysical survey and Phase 2 Site Assessment services!