Dynamic Solutions

Key Staff


Dynamic Solution’s senior staff and associates include experts in hydrology, hydraulics, hydrodynamics, water quality, limnology and oceanography, coastal engineering, groundwater and contaminant hydrogeology, computer programming, numerical modeling, statistics and mechanical engineering.

Christopher M. Wallen, MS, PG – Vice President and Principal

Mr. Wallen is a principal owner and operator of Dynamic Solution, LLC, a nationally known coastal and water resources consulting engineering firm that specializes in hydraulics, watershed hydrology and multi-dimensional modeling of hydrodynamics, sediment transport, water quality, contaminant transport/fate, fisheries and aquatic ecology.  He is a registered Professional Geologist and environmental engineer with over 31 years of consulting experience in surface water modeling to support assessments of hydrodynamics, sedimentation, nutrients, eutrophication, hypoxia, sediment bed remediation, flooding, coastal inundation and sea level rise, Minimum Flows and Levels (MFLs), NPDES Permits, Total Maximum Daily Loads (TMDLs), thermal impact, environmental investigations, and litigation support.

Mr. Wallen has directed hydrodynamic, sediment transport, water quality, and contaminant fate modeling studies in over 25 states on some of the largest and most complex waterways in the nation including Newark Bay/Lower Passaic River, Housatonic River, Lower Fox River, Columbia/Willamette Rivers and Portland Harbor, Kalamazoo River, Ohio River, Mississippi River, Illinois River, Sacramento San Joaquin Delta, embayments of the Louisiana Gulf Coast, and the Everglades. His involvement in high-profile surface water modeling projects and remedial investigations includes design of the modeling and investigational approach, data collection/analysis, coordination and management of multidisciplinary engineering scientific teams, quality assurance, and coordination and negotiations with regulatory agencies and Stakeholders.

He has supported litigation as an expert witness for a number of high profile environmental compliance and navigation cases throughout the United States. He has managed sediment bed contamination projects in industrial waterways, including the Housatonic River, Lower Fox River, Kalamazoo River, Columbia-Willamette River/Portland Harbor, and Newark Bay/Lower Passaic River, to support Superfund Site litigation cases to determine cleanup strategies and apportionment of liability for remediation of contaminants and cleanup costs among Principal Responsible Parties.  He has directed litigation cases and served as an expert witness for inland waterways, including the Lower Mississippi River, the Illinois River, and the Ohio River, related to barge accidents and bridge failure from scour/sedimentation in navigable waterways. He has supported litigation for an interstate water dispute where he directed assessments of the impact of river inflow and sea level rise on coastal inundation, salinity intrusion, nutrients, and decline of shellfish and fishery resources in Apalachicola Bay in Florida.  In support of CWA litigation involving an NPDES permitted industrial discharge, he provided expert witness testimony to present an assessment of the impact of the wastewater discharge on compliance with water quality standards and the occurrence of a large fish kill in the Ogeechee River in Georgia.

Mr. Wallen has expertise in the following capabilities:  Litigation Support and Expert Witness ♦ Hydraulic/Hydrologic Watershed Modeling ♦ Groundwater Modeling ♦ Hydrodynamic Modeling ♦ Sediment Transport Modeling ♦ Contaminant Fate Modeling ♦ Water Quality Modeling ♦ Client Representation at Public Meetings ♦ Project Management ♦ Minimum Flows and Levels ♦ NPDES Permits and TMDL development

William McAnally, PhD, PE, F. ASCE – Senior Water Resources Engineer

Dr. McAnally is a nationally recognized coastal engineering, sediment transport and navigation expert with 34 years of professional experience. His experience includes 33 years with USACE Coastal and Hydraulics Lab, Engineer R&D Center performing and supervising hydraulics, sedimentation, and transportation studies. He previously served as Technical Director for all USACE Navigation-related research. He is a registered professional engineer in Mississippi and has led numerous successful projects involving riverine and waterways design and environmental enhancement. Dr. McAnally led the team that created the USACE TABS numerical modeling system, co-wrote the TABS sediment transport model, and conducted multiple applications of the system. He has authored more than 80 publications, including a chapter in the upcoming ASCE Sedimentation Engineering Manual. Dr. McAnally has particular expertise in the following capabilities: Hydraulic Modeling | Hydrodynamic Modeling | Sediment Transport Analysis and Modeling | Coastal and Inland Navigation Studies | Model and Software Development

Andrew Stoddard, PhD – Senior Environmental Engineer

Dr. Stoddard is a nationally recognized water quality modeling expert with 33 years of professional experience in academic research and environmental consulting. He specializes in the application of hydrodynamic, hydraulic and surface water quality models for assessments of the ecological effectiveness and environmental benefits of water pollution control policies and regulations as mandated by the Clean Water Act. He has extensive experience in conceptualizing, planning and executing innovative “data mining” activities of large databases for (a) data assimilation in environmental models and (b) statistical analyses of national, regional, and local-scale water quality status and trends.

Using rigorous “data mining” techniques, Dr. Stoddard was able to detect, for the first time, statistically significant national, regional and local-scale “signals” of water quality improvements that have resulted, in part, from the technology-based regulatory policies of the Clean Water Act. The results of this important study were published in 2002 by John Wiley & Sons, Inc. as Municipal Wastewater Treatment: Evaluating Improvements in National Water Quality. He has also authored a number of technical publications including peer reviewed book chapters published in Oceanic Processes in Marine Pollution, Vol. 5: Urban wastes in coastal marine environments (1988); Coastal and estuarine studies, Novel phytoplankton blooms: Causes and impacts of recurrent brown tides and other unusual blooms (1989) and The Hudson River Ecosystem (in press,2004).

Dr. Stoddard developed comprehensive pre-processing software to incorporate EPA’s WASP5 eutrophication and toxics water quality models as the surface water quality model in EPA’s Office of Water National Water Pollution Control Assessment Model (NWPCAM). The NWPCAM framework, applied on a national-scale using EPA’s River Reach File-based hydrologic network of inland rivers, lakes and tidal waters, is used for assessments of policy-related water quality and economic benefits. Dr. Stoddard is a part-time instructor for a graduate level multi-media environmental modeling course. Dr. Stoddard has specific expertise in the following capabilities: Hydrodynamic Modeling | Sediment Transport Modeling | Chemical Fate Modeling | Water Quality and Eutrophication Modeling | TMDLs and Waste Load Allocations | Regulatory Policy Evaluations | Industrial Discharge Analysis Modeling

Silong Lu, PhD, PE, D.WRE – Senior Water Resources Engineer and Hydrologist

Dr. Lu has 24 years of research and consulting experience in groundwater hydrology, watershed hydrology, surface water and coastal hydraulics and hydrodynamics. His expertise includes groundwater flow, fate and transport, and density-dependent saltwater intrusion modeling; watershed and hydraulic modeling; hydrodynamic, sediment, and water quality modeling of rivers, lakes, wetlands, and estuaries; coastal tide and wave analysis and modeling; water resources planning and management; hydraulic structure design and physical model construction and testing; hydrologic and hydrogeologic data collection, evaluation, and analysis; and computer and GIS programming. Dr. Lu has served as technical reviewer, technical lead, project lead, task manager, and project manager on numerous projects. In addition, he has reviewed papers for Water Resources Research, Journal of American Water Resources Association, and Transport in Porous Media. Dr. Lu has mastered numerous watershed, surface water, and groundwater models including MODFLOW, MT3D, SEAWAT, MODPATH, VLEACH, HEC-1, HEC-2, HEC-HMS, HEC-RAS, EPD-RIV1, EFDC, WASP, TR-66, LSPC/HSPF, and WAM, and possesses working knowledge of SWMM, STWAVE, ADCIRC, SWAN, and RMA2.

Shaye Sable, PhD – Senior Aquatic Biologist/Ecological Modeler

Dr. Sable is an aquatic/fisheries biologist and ecological modeler with extensive experience developing and applying population, community, and food web models to evaluate population and ecosystem responses to changing environmental conditions, habitat, and stressors such as invasive species and exposure to toxicants.  She has linked her models to time series of environmental data and hydrodynamic models to explore how aquatic populations respond to freshwater river diversions and marsh habitat degradation.  Dr. Sable has developed complex, process-based ecological models of many areas along the Louisiana Coast and Suisun Bay in the Sacramento-San Joaquin Delta.  Dr. Sable has provided scientific guidance, expert opinions, and data analyses to support project development teams for freshwater diversions along the Mississippi River in relation to determining the diversion ecological cause and effect relationships due to changes in salinity, hydrology and sediments in the receiving basins.

Jan Mandrup-Poulsen, MS – Senior Water Quality Specialist

Having recently retired from the Florida Department of Environmental Protection (FDEP), Mr. Jan Mandrup-Poulsen brings more than 30 years of experience in the fields of water quality data collection, data analysis, Total Maximum Daily Load (TMDL) and Water Quality-Based Effluent Limitations (WQBEL) development, and watershed evaluation, protection, and restoration.  He was a co-author on the rules to establish Florida’s methodology for assessing the health of the state’s surface waterbodies, which serves as a model for the nation.  Jan was invited to advise the US Congress and EPA as a member of the committee to assess the Scientific Basis of the Total Maximum Daily Load Approach to Water Pollution Reduction and was a co-author of the National Research Council’s publication “Assessing the TMDL Approach to Water Quality Management” (National Academy Press, 2001).  He has been an active member of several state and national committees tasked with taking on the challenges of understanding and finding reasonable solutions for the nutrient and bacteriological pollution problems facing our nation. Jan was the project leader during the 10-year period it took to gather and assess data, while coordinating with academic and industry experts in the fields of air emissions, deposition, and mercury transformation, whose expertise was needed to support drafting and adopting the statewide TMDL for mercury reductions in fresh and marine fish.

He has been qualified as an expert witness, and whose testimony was critical in winning cases on behalf of the Florida Department of Environmental Protection.  Jan’s leadership allowed for the successful completion of over 300 TMDL reports, addressing a wide range of water quality issues in Florida’s lakes, rivers, estuaries, and coastal waters, thus allowing for the timely resolution of EPA’s TMDL Consent Decree in Florida.  He is a frequent invited speaker at state and national conferences and public meetings, addressing topics ranging from environmental policy to the technical development of watershed restoration plans.  Mr. Mandrup-Poulsen provides a skill set that brings a depth of knowledge and experience to Dynamic Solutions, LLC that offers clients the confidence of a representative that can meet the challenges of finding cost-effective solutions for complying with the point source effluent or stormwater (MS4) requirements required by their National Pollutant Discharge Elimination System (NPDES) permits.

Zhijun Liu, PhD – Environmental Scientist and Modeler

Dr. Liu has 15 years of research and consulting experience in watershed hydrology and water quality, and coastal hydrodynamics and water quality modeling of rivers, lakes, and estuaries. He has a Ph.D. in agronomy, M.S. in ecology, B.S. in forestry, and a minor degree in civil and environmental engineering. He is highly experienced with many watershed, hydraulic/hydrodynamic sediment transport, and water quality models including HSPF, EFDC, WASP, QUA2K, SWMM, and HEC-RAS. He has served as reviewers for Journal of the American Water Resources Association, Journal of Environmental Management, Environment Monitoring and Assessment, Journal of Environmental Science and Health Part A Toxic/Hazardous Substance & Environmental Engineering, Journal of Coastal Research, and Journal Scientia Agricola.

Gaurav Savant, PhD, PE – Water Resources Engineer & Numerical Modeling Specialist

Dr. Savant has 10 years of experience performing applied research studies of rivers and estuaries and developing numerical hydrodynamic models.  For the last six years Dr. Savant has been a key developer of the USACE’s state-of-the-art hydrodynamic model, the Adaptive Hydraulics Model (ADH). He has worked side-by-side with ERDC staff writing code, testing algorithms, performing verification tests and applications of the model.  Dr. Savant has also performed numerous studies using other multi-dimensional models such as CH3D and EFDC.   Additionally, he has conducted engineering design analyses and water resource studies using tools such as HEC1/HMS, HEC2/RAS, and QUAL2E.  Dr. Savant recently became a member of the Ports and Harbors Committee of the ASCE’s Coasts, Oceans, Ports, and Rivers Institute.

Steve Sanborn, MS, PE – Water Resources Engineer

Mr. Sanborn is a Water Resources Engineer with 10 years experience performing a wide range of river and estuarine studies throughout the USA.  He has a Master’s Degree in civil engineering, focused on eco-hydraulics and is a registered professional engineer in the states of Louisiana, Tennessee, and Oklahoma. Steve has extensive experience developing hydrodynamic models using the USACE’s advanced multidimensional hydrodynamic and sediment transport model the Adaptive Hydraulic (ADH) model, performing hydro-geomorphic studies, sediment transport analyses, river surveys, literature reviews, and ecosystem restoration studies.  Additionally, Steve has been the lead instructor for many ADH training courses.

Christopher L. Hall, PhD, PE – Water Resources Engineer

Dr. Hall is a water resources engineer specializing in hydrodynamic modeling, fluid mud modeling, fine sediment transport, best management practices, and resource conservation.  His education and experience in biological engineering, environmental engineering, and civil engineering have provided him with an understanding of the biological processes that occur in the environment and unique insight into the biological effects of hydrodynamics on the environment.  Dr. Hall’s research focus was fine sediment behavior, specifically fluid mud.  This is a fine-grained sediment suspension that occurs in many ports around the world and can impact navigation by restricting port access from increased deposition.  He is developing an open source two-dimensional hydrodynamic code to describe fluid mud behavior.  Dr. Hall has hydrodynamic modeling experience with several 1-, 2- and 3-dimensional hydrodynamic models including ADH, HEC-RAS, HEC-ResSim, and EFDC.  He has experience modeling many different types of domains, including rivers, bays, marshes, and estuaries, with tidal and river inflow boundaries.  Dr. Hall has worked on field data collection studies involving water quality and sediment samples as well as bathymetry studies.  His modeling experience with the USACE Sacramento included using ADH with extensive wetting and drying to study island flooding after levee failures.  He has programming experience in VBA, C, FORTAN, and MATLAB.

Julie A. Wallen – President, Mechanical Engineer

Ms. Wallen, the President of Dynamic Solutions, LLC, has successfully built the firm into a national leader in multidimensional modeling, visualizations, and programming engineering.  In 1996 she founded Dynamic Solutions, hiring senior-level engineers and associates with prior work experience to shape the firm’s strategies, structure, and performance with the objective of providing advanced computer modeling, water resource engineering, and uncompromising service.  Ms. Wallen provides leadership for the firm and manages all accounting and financial concerns, overseeing business development, marketing, contractual commitments, human resources and administrative affairs.  Ms. Wallen has over 28 years of professional experience providing support to multidisciplinary engineering projects for the Federal Government, States agencies, and private sectors.  She has extensive consulting experience with USDOE, USEPA and USACE projects and has performed management functions on projects requiring hydrologic, hydrodynamic and sediment transport modeling studies, data analysis and reporting.  Serving as the Contract Administrator, she has full responsibility for successful contract completion, including negotiating with third parties, conducting performance assessments, and evaluating budgets and bids.

Ms. Wallen has specialized experience in operational readiness for environmental remediation projects at Department of Energy (DOE) sites. She has provided support to DOE Environmental Management contractors during the preparation, planning, and execution of radiological and nuclear activities, relating to site mobilization, construction and operations of facilities or process systems.  By integrating the criteria of readiness in the early stages of project planning, she has provided detailed project scheduling of activities cross-referenced to management prerequisites, and continues to maintain the progress of the various disciplines’ objectives to determine critical path.  With a Mechanical Engineering degree, Ms. Wallen has particular expertise in Piping Design and Analysis; Process Flow; Conceptual and Detailed Design; Systems Engineering; Mechanical Integrity Programs, and Procedural Documentation.

Kate Watkins, PhD – Fish Biologist/Ecological Modeler

Dr. Watkins is a fish biologist and ecological modeler with experience modeling food web ecology and studying spatial structure in both observed and simulated populations.  She has experience working with spatially-explicit ecosystem models of coastal Louisiana to assess the effects of freshwater river diversions on community structure and the spatial distribution of individual populations.  Dr. Watkins has developed models to predict the distribution and movement patterns of individual fish in response to environmental factors, and evaluated the performance of a number of movement models in habitats with varying degrees of structure, across a range of spatial and temporal scales, and in response to dynamic environmental conditions.  She has also studied the population dynamics and mixing rates of observed populations with overlapping distributions.