Link to PFOS-PFOA page

Link to CE Online Page

Remediation Tools

Site Cleanup Software

Green Remediation Focus

Screening Matrix

The appearance of hyperlinks does not constitute endorsement by the Air Force Civil Engineer Center, the U.S. Air Force or the Department of Defense, of the external website, or the information, products or services contained therein.

Reach-Back Center

The Reach-Back Center is dedicated to assisting Department of Defense civil engineers in the execution of their mission across the full operational spectrum.
Toll Free: 1-888-232-3721
Comm: 1-850-283-6995
DSN: 312-523-6995
Email: AFCEC.RBC@us.af.mil

Hydrogeology

Hydrogeology

Mission - The Hydrogeology specialty area supports the enhancement of an installations' critical natural resources infrastructural knowledge, maximizes operational land use and minimizes Air Force environmental liabilities through experienced technical leadership and guidance.

Vision - Achieve common recognition of high-level principles for identifying hydrogeology practices that support investigation strategies and decision logic to allow for better protection of human health, safety, and the environment.

Overview - The Hydrogeology Specialty Area has four subareas of operation: site-specific geology, groundwater flow, groundwater/surface water interaction, and water quality and is responsible for facilitating increased application of sound hydrogeological principles and practices in the areas of environmental management, compliance and restoration. This specialty area provides subject matter expertise in understanding fundamental geologic and hydrologic issues at installations across the Air Force and integrates an installation's geological and hydrological natural resources into the Natural Infrastructure Assets Management Plan.

Groundwater/Surface

Groundwater/Surface Water Interaction

The groundwater system as a whole is a three-dimensional flow field where the vertical components of groundwater movement in shallow aquifers affect the interactions of groundwater and surface water.

Surficial aquifers recharge through rainfall and infiltration into the upland areas between drainages and discharges into local streams and rivers.

Groundwater Flow

Groundwater Flow

Groundwater flow is an important aspect of hydrogeology because it is used to demonstrate groundwater movement principles. Groundwater moves from areas of higher elevation or higher pressure/hydraulic head (recharge areas) to areas of lower elevation or lower pressure/hydraulic head, along the hydraulic gradient. The magnitude of groundwater flow depends on both the hydraulic gradient and the soil characteristics.

Groundwater flow in aquifers ultimately is released into streams, lakes, wetlands, or springs (discharge areas). The direction of groundwater flow normally follows the general topography of the land surface. The more permeable the aquifer material, the higher the rate of groundwater flow and discharge.

Site-Specific Geology

Site-Specific Geology

The geologic conditions of a site are used to understand the elements that create the natural infrastructure of the land that includes the following: physiographic setting; the general nature of geologic units; controlling regional geologic features; geologic units beneath the site and their thicknesses; and origin of deposits (channel sand, lake deposits, etc.).

Site-Specific GeologyAny special features that would affect fate and transport of contaminants are evaluated in addition to local features that could impact groundwater flow and contaminant distribution around a site (faults or other controlling structures, confining layers, caliche zones, etc.).

Conceptual Site Model

Conceptual Site Model

The hydrogeology specialty area has identified approaches for Conceptual Site Model, or CSM, development to explain critical geological issues, complex hydrological flow, and contaminant movement at site-specific and base-wide locations. The development of CSMs presents a three-dimensional picture of site conditions that illustrates environmental radionuclide distributions, release mechanisms, exposure pathways and migration routes, and potential receptors.

The CSM demonstrates current site conditions supported by maps, cross-sections, lithostratigraphic/hydrostratigraphic columns, and site diagrams that illustrate human and environmental exposure through contaminate release and migration to potential receptors. These approaches are responsible for accelerating the process for defining the nature and extent of contaminants, as well as addressing site restoration in a systematic and efficient manner.

Effective site management and restoration are dependent on a clear understanding of surficial and subsurface conditions and how installation activities ensure the protection of human health and the environment. The hydrogeology specialty area provides support in understanding complex geological and hydrological issues through expert advice in evaluating site contamination, specifically at challenging sites, through groundwater modeling and review services for contaminant fate and transport.

Water Quality

Water Quality

Human activities commonly affect the distribution, quantity, and quality of water resources. The range in human activities that affect the interaction of groundwater and surface water is broad. For nearly every type of water use, water possesses increased concentrations of dissolved constituents or increased temperature following its use. Therefore, water quality of the aquatic bodies that receive discharge or return flow are affected.

Contaminants in streams can easily affect groundwater quality, especially where streams normally seep to groundwater, where groundwater withdrawalsinduce seepage from the stream, and where floods cause stream water to become bank storage. The tendency for chemical contaminants to move between groundwater and surface water is a key consideration in managing water resources. Furthermore, groundwater and surface water interactions have a major role in affecting chemical and biological processes in lakes, wetlands, and streams, which in turn affect water quality throughout the hydrologic system.