Monday, June 23, 2008 : 9:50 a.m.

ASR: Ground Water Modeling and Considerations for Implementation Success

Kristina K. Masterson, PE, Matthew Gamache, PE and Robert Fitzgerald, PE, CDM Inc.

ASR is a water supply management practice employed by water purveyors and managers in many regions of the US including the northeast. Successful implementation of ASR requires a careful review of the hydrogeologic conditions and groundwater flow patterns near the ASR site, the development of an operations plan specifically tailored for the injection site, and a field program to monitor injection and recovery operations and impacts. Groundwater model simulations can be used to assist in the implementation and design of an ASR system, as well as to help assess the effectiveness of the system, once implementation has begun.

Monitoring data and model simulations of actual ASR operations in Washington state, as well as hypothetical ASR model simulations on Long Island, NY are presented to demonstrate the hydrogeologic factors that could affect ASR operations and to provide guidance on the development of monitoring plans designed to track ASR operations, in particular the amount of injected water that is recovered.

In Washington, groundwater flow simulation results of ASR operations compare favorably to measured data from an ASR site. On Long Island, hypothetical model simulations were used to better understand the percent recovery of injected water that should be expected when performing ASR operations in a coastal aquifer. In both cases, model results suggest that percent recoveries range from 60 to 80% of injected water due to ambient flow within the aquifers used for ASR and, to a lesser degree, hydrodynamic dispersion. Since excessive mixing with native water is undesirable due to water quality and treatment concerns, model simulations can be used to determine the amount of mixing expected and make recommendations regarding ASR operations. These results demonstrate the applicability of groundwater flow models to study the feasibility and potential success of ASR in different hydrogeologic settings.

Kristina K. Masterson, PE, CDM Inc. Ms. Masterson is a water resources engineer who specializes in groundwater flow and contaminant transport model simulation analysis. Ms. Masterson has conducted groundwater flow and mass transport modeling studies for site environmental assessment, remediation investigation and design, remediation performance evaluation, and water resources management projects. During the 20 years that she has worked in the water resources engineering field, Ms. Masterson has successfully applied numerical groundwater flow and mass transport models to study groundwater flow patterns and contaminant mass transport characteristics in many different hydrogeological settings.

Matthew Gamache, PE, CDM Inc. Mr. Gamache is a water resources engineer who specializes in subsurface hydrologic and contaminant transport modeling. These models have been used to assess groundwater flow paths, travel times, and contaminant concentrations for litigation support, delineation of drinking water protection zones, and design of groundwater remediation systems.

Robert Fitzgerald, PE, CDM Inc. Mr. Fitzgerald is a Senior Groundwater Modeler who has been responsible for numerous studies of groundwater flow and dissolved and separate phase contaminant transport in aquifers. Mr. Fitzgerald also has extensive experience in hydrology, hydraulics and water resources management, emphasizing the application of computer simulation models. He has been responsible for the use of models in analyzing and developing programs for groundwater management and remediation, flood alleviation, reservoir yield augmentation and water quality assessment.


2008 NGWA Conference on Eastern Regional Ground Water Issues