Water Assessments and Investigations


Hydrogeologic Investigations

ENW has successfully completed highly visible water supply and water resource work. This broad-based experience in both water supply and contamination investigations is available to our clients in both the private and public sectors, including:

  • Environmental investigation and remediation

  • Source evaluations in domestic and production wells impacted with agricultural chemicals, e.g., ethylene dibromide (EDB), 1,2-dichloropropane (DCP) and 1,2,3-trichloropropane (TCP)

  • Solid waste facility siting, design and cleanup

  • Water supply for domestic and commercial developments

  • Water rights (CWRE)

    • Transfers

    • Claims of Beneficial Use

  • Aquifer tests

    • Slug tests

    • Pumping tests

  • Water resource studies for preservation of anadromous fish runs, and hatchery design

  • Geothermal energy resource assessment and utilization

  • Golf course design and resource development

  • Dam and hydropower facility design and impact assessment

    • Dam leakage assessment

  • Tunneling studies

  • Watershed planning

  • Stream bank restoration

  • Level 1 and 2 Critical Aquifer Recharge Area (CARA) assessments

Ground water modeling

Modeling is the process of using computer simulation techniques to reproduce the hydrogeologic and environmental conditions at a site. In groundwater modeling, the processes of groundwater flow in response to natural and imposed hydraulic head differences, advection, diffusion, dispersion, chemical equilibrium, absorption and chemical decay, leakage, withdrawal, and recharge can all be described with the mathematical language of the computer program and applied to a simplified two- or three-dimensional representation of subsurface conditions. Once the simulation is considered reasonably accurate, the model can be used to test hypothetical scenarios.

ENW applies groundwater models effectively for Prediction, Aquifer Characterization, Risk Assessment, and Remediation:

  • Prediction

    Models are used for describing ground water flow patterns and assessing impacts to aquifers and water resources under different ground water resource stress scenarios. Predictive models can also address future migration, expansion, and attenuation of contaminant plumes. The predictive function facilitates resource planning. ENW utilizes Groundwater Modeling System (GMS) as a base for most intricate modeling projects. GMS is the most advanced and comprehensive ground water modeling front-end package (i.e., graphical user interface) available. The program was developed under the direction of the U.S. Army Corps of Engineers and involves support from the Department of Defense, the Department of Energy, and the Environmental Protection Agency.

  • Aquifer Characterization

    ENW uses a variety of computer programs for analysis of aquifer parameters and well-field performance. These include AQTESOLV (a program that performs curve-fitting analysis to a wide range of aquifer test solutions and variable head test solutions), THCVFIT (which fits drawdown data to the Theis equation), THEISFIT (a statistical best-fit program for fitting drawdown data to the Theis equation), VARQ (a variable discharge pump test analysis package), and OPTP/PTEST (uses variable discharge pump test data to determine optimum pumping discharge). When ENW prefers to analyze aquifer characteristics outside of the constraints of prepared programs, our hydrogeologists use Microsoft Excel, a spreadsheet program with excellent graphic capabilities, which can also export data to and from other formats. ENW is experienced with using sophisticated electronic pressure transducer systems (made by In Situ) to acquire and record high-quality data during pump test and down-hole testing procedures.

  • Risk Assessment

    Modeling of impacted hydrogeologic systems can assist in matters of public policy, planning, and response. ENW has used modeling to assess the risk to water well owners, public water supplies, surface waters, and industrial-agricultural users.

  • Remediation

    ENW staff have been frequently called upon to remediate sites where ground water has already been impacted. In attempting to remediate a ground water contamination site, several alternative technologies may be considered. Groundwater modeling is used to test the configuration of various arrays of extraction wells to determine the most efficient capture scenario for an expanding, migrating plume. Cost-efficiency and time-efficient performance frequently are the deciding factors among the various alternatives.


Natural Resource Assessment

ENW provides a variety of natural resource assessment services including wetland determination and delineation, watershed and drainage basin assessment and mitigation, vegetated corridor assessment and mitigation/enhancement, and stream assessments. We have worked with a variety of agencies, including city, county, and state officials, to assess properties and obtain the necessary permitting and mitigation or enhancement plans to help move our clients’ projects forward.

Watershed and Stream Assessment and Restoration

To achieve long-term success on watershed and stream restoration projects demands a complete understanding of the physical and biological processes occurring within a channel. ENW evaluates the entire contributing watershed for each stream-restoration project. This investigation approach provides team members with extensive insight into a channel’s dynamics and allows us to examine the systemic processes within the channel's reach.

Successful watershed and stream assessment and restoration is based on understanding the fluvial morphology, hydrologic setting, climatic factors, habitats, and ecosystem functions of a particular stream reach. The natural condition or potential of an impacted stream reach may be compared to a similar stream reach that has not been impaired (i.e., reference reach). ENW provides full-service stream restoration capabilities incorporating stream habitat assessments, Rosgen stream classifications, hydrologic/ hydraulic analyses, water quality assessments, and detailed stream restoration plans.

Stream restoration can provide a low-cost solution to chronic erosion and sedimentation problems, resolve water quality issues, and/or to restore habitat. Whether the project is a master-planned residential community, commercial development, golf course, public land, or private residence, stream restoration may provide an opportunity to enhance the landscape and the environment by improving water quality for important beneficial uses such as irrigation, storm-water management, recreational use, habitat, or aesthetic quality. ENW also conducts these studies to establish baseline water-quality conditions and/or to develop long-term water-quality monitoring programs.

By completing a detailed assessment, ENW can develop a restoration plan for the stream that is cost-effective, eliminating redundant efforts and simplifying post-restoration monitoring. ENW applies useful classification systems as part of the overall stream restoration process based on methods described by Dave Rosgen, the U.S. Forestry Service, and the Natural Resource Conservation Service’s (NRCS) Stream Visual Assessment Protocol.

ENW’s team of professionals address all facets of the restoration design process so that local, state, and federal agency requirements are met. ENW conducts the necessary hydraulic/hydrologic modeling that incorporates bankfull width, depth, channel and bank slope, and flow velocity as well as dimensionless ratios of various stream geomorphological properties (based on the work of Dave Rosgen) to identify the most appropriate restoration technique.

Restoration techniques include:

  • Instream structures (i.e. cross vanes, weirs, and step-pool complexes)

  • Bioengineering methods such as cut or fill, vegetated geogrids, live-staking and fascine bundles.

ENW is experienced at completing work throughout the Pacific Northwest region, which facilitates timely plan review and implementation. Our experience and dedication to detail allows for the most appropriate, cost-effective solution to be determined. ENW works closely with the selected contractor to ensure that the plans are implemented to specifications and oversees the completion of the as-built structures.

Long-term monitoring of a restored stream provides data that determines the success of restoration. Monitoring may also be used to evaluate whether a stream has adjusted to land use changes in a watershed, which can affect water quantity and quality. ENW hydrologists and geologists conduct post-construction monitoring efforts, focusing on the restored stream morphology and channel system, survival of riparian plantings, and identification of water quality and habitat benefits derived from the project. Monitoring efforts are developed in accordance with permit conditions and are summarized in an illustrated report documenting all findings and restoration activities.