New Mexico Geological Society Annual Spring Meeting — Abstracts

Recently, the City of Albuquerque began investigating the feasibility of artificial recharge of the Albuquerque aquifer. Artificial recharge by both. subsurface injection and surface inftltration are under consideration. Proposed recharge fluids are 1) treated effluent from the Albuquerque wastewater treatment facility and 2) Rio Grande surface water. This study used the hydrogeochemical models PHREEQE and MINTEQA2 to simulate both subsurface injection and surface infiltration. The purpose of the hydrogeochemiciu modeling was to attempt to answer the following questions: 1) is it likely that minerals will precipitate during artificial recharge and clog the pore space in the aquifer thus limiting the useful life of artificial recharge sites and 2 ) what will the effect of artificial recharge be on water quality? Changes in water quality can occur from precipitation of minerals, dissolution of minerals, absorption/desorption effects, and mixing of the recharge water with the groundwater. Water quality changes from these mechanisms may be either detrimental or beneficial.

As a basis for comparison, simulations were also performed with data from the successful EI Paso artificial recharge project. The results suggest that subsurface injection of Albuquerque treated effluent will be successful, and that subsurface injection of Rio Grande surface waters will probably be successful. Simulations of surface inftltration predict a possibly significant amount of mineral precipitation in the vadose zone, which might limit the life of a surface inftltration facility. The simulations predict no adverse impact upon water quality due to artificial recharge. However, trace metal distribution, ion exchange, bacteriological content of the waters, or the presence of potential pollutants are not considered by the models. Chemical pilot-testing and kinetics-based computer modeling are recommended to predict the useful life of recharge facilities. Equilibrium-based models, such as used in this study, cannot determine the potential life of a recharge facility.