Soil Investigations

Soils are a portion of the earth’s crust in which terrestrial and subaqueous plants can grow. They consist of mineral particles, water, air, and organic matter. They also provide a medium to filter and treat contaminants, a basis for construction, and habitats for various organisms.  All soils develop from weathered rock, volcanic ash deposits, and accumulated plant residues, and exhibit character influenced by climate, organisms, parent material, topography, and time.  Soils are the foundation upon which many of our natural resources depend.  Precise assessment and characterization of soils is paramount in development of accurate land and resource management strategies.  Utilizing accurately assessed soil information, O.C. Reedy Associates, Inc. (ORA) routinely assists our clients in complex natural resource management issues relating to:

  • Habitats Design
  • Ecosystem Management
  • Building Foundation Suitability
  • Crop Management
  • Land Application Suitability
  • Storm- and Wastewater Treatment

Hydric (Wetland) Soil Identification

Under Section 404 of the Clean Water Act, soils, hydrology and vegetation are assessed to determine the limits of Wetlands.  The United States Department of Agriculture’s (USDA) Natural Resource Conservation Service (NRCS) defines a hydric soil as “a soil that formed under conditions of saturation, flooding or ponding long enough during the growing season to develop anaerobic conditions in the upper part.”  As vegetative and hydrologic evidence are often the most readily observable parameters sole reliance on either as a determinant of wetlands can be misleading.  Therefore, it is crucial to be able to determine the hydric/non-hydric status of the onsite soils for correct wetland determination.

“Field Indicators” are soil characteristics documented to be strictly associated with hydric soils, and they are an efficient means to confirm the presence of hydric soils onsite.  The Field Indicators are designed to identify soils meeting the hydric soil definition without further data collection.  With over 46 published USDA NRCS hydric soil Field Indicators in use, it is critical to accurately identify the indicators present for a precise jurisdictional wetland boundary determination.  ORA’s extensive experience in hydric soil identification provides our clients with the most representative depiction of their onsite jurisdictional wetlands.

The identification of hydric soils also extends to crop management where in recent years, a contributing factor of diminished crop yields has been attributed to excess saturation; yields are dramatically reduced if crops are planted in soils that experience ponding or root zone saturation. The hydric soil Field Indicators are used to identify and delineate these areas.  Once hydric soils have been identified and delineated, strategies to avoid these areas or manage this condition can then be developed and implemented.  If avoidance is not a viable option, subsurface drainage systems (tiles and French drains) are typically utilized to manage excess water conditions thereby maintaining or increasing crop productivity.

Soil Mapping

Every stormwater and wastewater project begins with an understanding of the geologic processes and soil types that comprise the land.  A firm understanding of landscapes and their relation to soil types allow ORA’s professionals to produce high intensity soil surveys that identify the best areas for land application of waste sites, stormwater management systems, and wastewater treatment systems.  ORA’s professionals are well versed in various state-specific soil mapping requirements and procedures.  For instance, the State of Georgia’s Department of Community Health requires USDA NRCS classification (to the Series level) of at least one soil boring per quarter-acre of land for residential developments served by individual onsite wastewater treatment systems.  Soil boring classification includes:  depth to the seasonal high water table, depth to restrictive layer(s), topographic information, and percolation rates.  ORA professional soil scientists record each soil boring location with sub-meter accuracy using global positioning system technology, ensuring that the soil surveys produced are of the highest purity.  This instrument allows ORA to work more effectively with our clients and our client’s teams of professionals to maximize resource potential

Forensic Soil Mapping

Disturbed lands, particularly those lands where the disturbances results from draining, dredging, or filling activities are becoming more common.  An essential component in habitat or ecosystem restoration is the proper identification of the sediments on which the alteration has occurred. ORA’s expertise in forensic soil mapping aids us in determining the limits of disturbed or destroyed ecosystems which benefits our clients in land acquisition decision making as well as permitting and mitigation processes.  Typical forensic soil mapping procedures include: 

  • Photo-interpretation using historical aerial imagery of subject lands.
  • Onsite soil classification (to the Series level) utilizing various investigative techniques (i.e., backhoe excavation, auger boring, etc.).
  • Production of high intensity soil surveys of disturbed subject lands depicting soil map units indigenous to specific habitats and ecosystems.
  • Coupling forensic soil mapping with other data sources to reconstruct disturbed or altered lands with an elevated level of precision. 

Foundation Investigations

Unsuitable or unstable subsurface environments are frequently encountered during land development.  High organic material (i.e., muck), shrink-swell clays and buried debris can be very dynamic and become unstable when loads are applied.  These environments can compromise the integrity of building foundations resulting in substantial financial loss.  ORA’s professionals will accurately characterize the subsurface environment in any proposed structure location to minimize the risk of foundation failure.  If areas of ‘suspect’ or unsuitable materials are encountered, ORA routinely recommends remedial strategies for project advancement.