Lower Dawson Aquifer ASR Pilot Project: LWS personnel conducted the first ever pilot project on ASR in the Denver Basin at a Lower Dawson aquifer well near Parker, Colorado. Cherry Creek alluvial ground water was used as the source water for injection, back flowing water through the submersible pump in the well, using the check valves in the pump column to maintain a positive pressure so water would not cascade down the borehole causing air entrainment. The success of this pilot project led to the further research into the technical feasibility of ASR through the US Bureau of Reclamation’s High Plains States Ground Water Demonstration Project through the Denver Basin six-year research project conducted by LWS personnel.
Denver Basin Ground Water Recharge Demonstration Project: LWS personnel were the project manager for the six-year research and development ASR project to assess the technical, economic, and institutional viability of ASR in the Denver Basin aquifers. This was the first major study of ASR in the Denver Basin and was conducted on an Arapahoe aquifer well, 1,600 feet deep with 16-inch casing. A monitoring well with similar construction was installed approximately 100 feet from the injection well. The results of the research indicated that ASR is technically feasible with the only issues being related to the introduction of highly-oxygenated source water into a reducing environment in the deep bedrock, which could cause adverse geochemical reactions depending on the formation matrix, and the large thermal difference between the ambient temperature of the aquifer and the temperature of the source water, causing significant viscosity changes which manifested itself as a change in aquifer transmissivity. As part of this study, LWS personnel assisted the State Engineer’s Office with the writing of the rules for extraction of recharged water, with the subsequent promulgation of the Denver Basin Extraction Rules.
Rapid Infiltration Basin and Injection Well Recharge Project in the Ogallala Aquifer: Because of declining water levels in the Ogallala aquifer, and an availability of excess surface water supplies from its mountain reservoir system, Cheyenne BOPU wanted to evaluate varying means of recharging the Ogallala aquifer to assess the efficiency of recharge and the ability to improve production rates. LWS designed a pilot study to test the efficiency of a rapid infiltration basin (RIB) by constructing a RIB within the Bell well field. To assess the ability of surface-recharged water to effectively reach the local water table, monitoring wells were installed adjacent to the RIB above each low-permeability clay between the ground surface and the local water table. During injection, each monitoring well was observed relative to the development of a local water table. The data indicated rapid movement through some of the clay zones while others saw significant head build up and more lateral movement of water than vertical movement. Because the local water table is relatively deep, approximately 80 feet to 100 feet below ground surface, the geology did not seem favorable for RIBs. The second portion of the pilot study evaluated the use of an injection well, which is not dependent on the geologic strata in the unsaturated zone. The results from the injection well testing indicated that water could be successfully recharged into the Ogallala aquifer, albeit at a lower rate than from the RIB.
Front Range Resources Recharge Project in the Lost Creek Basin: A large ASR project is proposed in the Lost Creek Basin on the Colorado Eastern Plains. LWS has installed several monitoring wells at three separate RIB locations to evaluate the local geologic strata and the potential efficiency of an ASR project. In addition, LWS has prepared a numerical ground water model to assess the ability to recharge water into the alluvial aquifer system and subsequently recover the water at remote well locations. Analysis of both the geologic and hydrogeologic data, as well as model results, has assisted LWS with developing an overall managed aquifer recharge plan.