Our groundwater sampling and analysis programs utilize the most technically advanced, cost-effective, and appropriate drilling and sampling techniques. We have extensive experience in downhole drilling methods including conventional rotary techniques (air, mud, reverse circulation), conventional and wire-line coring, air percussion techniques, Rotosonic, hollow-stem auger, and power auger drilling. We are also experienced in the use of various groundwater sample collection methods and equipment including peristaltic pumps, Grundfos pumps, bladder pumps, and bailer methods. We understand the applicability and limitations of these methods and equipment while providing cost-effective, quality services to our clients.
We have designed and provided construction oversight of single and multiple cased monitoring wells and nested well systems to assess water quality in complex hydrogeological settings. We utilize a variety of investigation methods including downhole video logging geophysical tests and packer tests to identify water-bearing zones and preferential contaminant transport pathways. We have extensive experience in the preparation of well design and construction specifications.
EnviroForensics is experienced in evaluating and developing groundwater resources for irrigation, potable use and industrial supplies. We evaluate potential groundwater resources through the analysis and interpretation of geological strata, borehole geophysical logs and aquifer tests. Our staff has performed well inventories; interpretation of existing hydrogeological data; conducted contamination assessments; implemented groundwater investigations; characterized physical and chemical characteristics of aquifers; prepared hydrogeological investigation reports; developed, performed and interpreted aquifer tests; worked with regulatory agencies; developed well construction specifications; and designed well fields. We are also experienced in well capacity restoration and rehabilitation and analysis of local and regional aquifer characteristics.
Our staff has extensive experience in the development and implementation of field investigation programs. We have used various borehole geophysical logging methods including resistivity, self-potential, natural gamma, and caliper testing to determine subsurface lithologic characteristics. Our experience also includes the design, interpretation, and use of aquifer pump tests, including constant-rate and stepped-rate tests, and borehole hydraulic conductivity test (slug tests) to determine aquifer hydraulic properties necessary for evaluation of groundwater resources. We have utilized these tests to estimate aquifer recharge, identify areas for favorable well development, and evaluate optimum well spacing to minimize interference effects.
Our hydrogeologists are experienced with a variety of computer modeling software to simulate groundwater flow and the fate and transport of contaminants that may impact drinking water supplies or groundwater resources. We have developed and applied these models for projects in broad hydrogeological conditions such as unconsolidated aquifers and fractured bedrock conditions. Our staff has used these models to evaluate impacts to groundwater resources due to the installation of new production wells and to analyze the migration of contaminants to determine if and/or when they may impact groundwater supplies. We are experienced in all aspects of groundwater modeling including conceptual hydrogeologic model development, model selection, mathematical
model development, model calibration, sensitivity analysis, model verification and predictive simulations. Some of the models we routinely use are MODFLOW, MODPATH, BIOPLUME III, GWPATH, GLFLOW, GWTRAN, SEQUENCE, BIOCHLOR, FEMWATER, and FEMWASTE.
Groundwater Restoration and Protection
EnviroForensics has assessed the extent of contamination as the basis for remedial engineering design and has developed and implemented monitoring programs to evaluate the effectiveness of remedial efforts. We have prepared sampling and analysis plans, designed groundwater monitoring networks, provided field sampling services for characterization of hazardous materials releases, executed public participation programs to obtain community input into the remedy selection process, successfully negotiated the cleanup objectives with regulatory agencies, and completed regulatory agency reporting requirements.
Our staff has provided removal oversight of hazardous wastes and materials from permitted and uncontrolled sites, in efforts to protect groundwater resources. We have provided design support and construction oversight for containment systems to protect groundwater from further impacts and to control the migration of existing groundwater contamination. We have dealt with a wide range of contaminants including petroleum hydrocarbons, solvents, polychlorinated biphenyls (PCBs) and metals. We have used low permeability landfill covers, slurry walls, and groundwater extraction and treatment systems. We have operated and maintained groundwater remediation systems such as air stripping, carbon adsorption, and vapor extraction systems.
We have conducted feasibility studies to develop, screen, and evaluate groundwater remediation alternatives to identify a preferred remedial alternative. Our feasibility studies have included wide range of technologies including pump and treat systems, chemical oxidation, aerobic treatment by methane injection, accelerated anaerobic bioremediation with hydrogen release compound (HRC), and reactive walls. We have also considered and evaluated the use of natural attenuation as a remedial approach. We have worked with various regulatory agencies.
We have experience in developing and completing bench-scale testing to determine the viability of remediation technologies, including evaluation of bioremediation and chemical oxidation technology using hydrogen peroxide and potassium permanganate. Radio labeled and microcosm tests were performed to determine microbial activity and determine the optimum environmental for microbe activity. We have designed and performed pilot tests using hydrogen release compound and bioremediation for groundwater restoration.
Seepage and Inflow Analysis/Groundwater Control (Interception Systems)
Our hydrogeologists are experienced in seepage and inflow analyses for surface conveyance systems, proposed excavations, and surface mines. Our evaluations include installation of wells to establish groundwater occurrence, flow directions, and soil stratigraphy; performance of pump tests to estimate soil and rock units permeability; and evaluation of potentiometric elevation data to assess groundwater gradients. We have used our evaluations to quantify seepage rates and quantities, to estimate pumping costs under future conditions, to appropriately size pumping equipment, and to determine the impact of proposed construction activities on local and regional groundwater levels and river inflows. We have evaluated existing hydraulic conductivity data, surface water flow rates, rainfall data, water levels, and land use maps to develop groundwater flow models including simulated effects under various pumping and construction scenarios.
Stream Quality Routing Models
Regulators set stream standards to avoid the aquatic stresses from point source loadings during low stream flow periods. Steady state stream quality routing models like QUAL2E have been designed to predict stream quality and allocate waste loads during such periods. While these models can be calibrated and run at high flows, they are typically inadequate for qualifying wet weather loads from municipal sources. Dynamic water quality models such as WASP are necessary to routing wet weather loadings downstream. EFI staff is capable of modeling river water and estuary water quality under different hydrologic conditions.
Reservoir Quality Models
Lake and reservoir models also range greatly in complexity and resource requirements. Reservoir simulation models require significant data and manpower for proper development, calibration, verification and application. Typically reservoir and lakes are simulated in one or two dimensions with material and energy transport estimated between stratified layers. In estuaries, three dimensional models may be necessary, particularly if dispersion of a discharge plume is needed to be predicted. EFI staff has applied this modeling in predicting lake quality under imposed conditions and improvements.