2016 NGWA Groundwater Summit

A numerical assessment of large screened monitoring wells on groundwater flow fields and solute distribution

Monday, April 25, 2016: 4:30 p.m.
Confluence Ballroom B (The Westin Denver Downtown)
Daniel Gomes , Water Technologies, Waterloo Hydrogeologic, Denver, CO
Robert J. Stuetzle , The Dow Chemical Company, La Porte, TX

Proper design and construction of monitoring wells is essential to obtain representative samples for further analysis such as fate and transport modeling, risk assessment and feasibility of remediation projects. Monitoring wells with large screens have been used for many years to monitor groundwater, and although this practice has been largely replaced by smaller screens in recent years, several legacy, large-screened monitoring wells are still in use at many sites, leading to potential for cross-connection between aquifers and less than efficient in situ remedies. This paper conducts a number of simulations using groundwater flow, particle tracking and solute transport analysis to assess potential impacts of such wells in providing short cuts for solute transport across different layers. The detailed numerical experiments use Modflow and MT3D to simulate groundwater flow and transport through porous media with large screened monitoring wells. The study compares using Modflow’s Multi Node Well (MNW) package as well as zones of high hydraulic conductivity to simulate monitoring wells. A number of scenarios are analyzed including monitoring wells located in recharge and discharge areas; in areas with horizontal flow conditions, under isotropic and anisotropic conditions and heterogeneities. The study also compares results of the numerical analysis with actual data from real sites to shed light into the potential for cross connection.

Daniel Gomes, Water Technologies, Waterloo Hydrogeologic, Denver, CO
Mr. Gomes is Waterloo Hydrogeologic’s Consulting Manager, with over 29 years of experience in groundwater flow and solute transport assessment and modeling. He received his BSC. in Geology (1985) and M.Sc. in Hydrogeology (2004) from the University of São Paulo, supervised by Dr. Bob Cleary. Prior to this position Mr. Gomes worked for Schlumberger Water Services and served as a technical expert for several agencies of the United Nations system. He is currently the main instructor Of NGWA’s New Modflow Short Training Course.

Robert J. Stuetzle, The Dow Chemical Company, La Porte, TX
Robert J. Stuetzle is a Hydrogeologist working as a Remediation Specialist for The Dow Chemical Company in La Porte, Texas. He earned his M.A.Sc in Water Resources Engineering supervised by Dr. Beth Parker and Dr. John Cherry, from the University of Guelph in Ontario, Canada in 2014 and a B.Sc. in Science and Business: Hydrogeology Specialization from the University of Waterloo in Ontario, Canada in 2010. He is also a registered Professional Geoscientist (P.Geo.) in Ontario, Canada.