Our senior staff has conducted hundreds of groundwater assessments in 30 states in accordance with differing state and federal regulatory requirements. Obtaining enough data points to overcome site and plume heterogeneity is a priority for those projects where remediation to low regulatory standards is needed.
Our staff also has extensive experience in different hydrogeological environments in assessing plumes of chlorinated solvents (including 1,4-dioxane), nutrients, petroleum hydrocarbons, MTBE, and inorganic compounds. These differing hydrogeologic environments include fractured bedrock, coastal plain sediments, and karst.
For routine and simple groundwater assessment projects, we use standard assessment methods such as auger or air-rotary and direct-push drilling rigs. Other methods commonly used include soil-gas surveys, geophysical surveys, and the collection of samples for testing for monitored natural attenuation parameters.
When methods are needed to help determine site and plume heterogeneity, methods such as membrane interface probe, laser-induced fluorescence, the hydraulic-profiling tool, or a mobile analytical laboratory are used to obtain high-density data. High-density data are needed in these instances so that the true distribution of the contaminant plume in the vertical and horizontal senses is better established. These data are especially helpful when targeted injections of chemical oxidants or bioaugmentation substrates is planned. A high volume of data points describing the heterogeneity in the soil matrix is also important.
Groundwater Assessment Projects
Duncklee & Dunham has a high level of experience in the design and installation of groundwater treatment systems including in-situ chemical oxidation (ISCO), monitored natural attenuation (MNA), microbiological augmentation, other injection approaches, air sparging, soil-vapor extraction, pump-and-treat with aeration, granular activated carbon, stripping towers and ion exchange.
A current project involves the collection of aquifer matrix data for input to the PHREEQC geochemistry model at a metals site in central North Carolina. Geochemical input data includes clay mineralogy, iron and manganese hydroxides, and total organic carbon. The model output will predict the amount of the metal that can be adsorbed by the aquifer matrix.
- Mr. Duncklee has served on two Interstate Technology & Regulatory Council (ITRC) teams. The first team worked on producing In-Situ Chemical Oxidation (ISCO) guidance documents. Currently, he is working with the Environmental Molecular Diagnostics (EMD) team. The EMD team is developing guidance documents for use in the United States regarding stable-isotope and molecular-diagnostic methods that are emerging technologies to predict plume degradation.
- A major oil terminal and adjacent property on the Ohio River in Kentucky has been assessed by Mr. Dunham under the National Contingency Plan. Unique challenges of this project include reversal of typical hydraulic gradients due to river flood stages along with complex clay and sand stratigraphy. MIP assessment, air sparging, soil-vapor extraction, a dewatering system combined with ex-situ chemical oxidation, bioaugmentation and infiltration, and a 2 MGD pump-and-treat system are being used in unison to protect a nearby municipal well field.