Agenda - Council - 02/26/2019 - Laserfiche WebLink

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Response: The City acknowledges these points and refers the commenter to the response to Comment #13.1. Comment #13. The Minnesota Department of Health (MDH) submitted the following advisory and technical comments: Comment 13.1: The wells used as a source of supply by the City of Ramsey's water supply system are completed in the FIG aquifer. Local indicators (as discussed in the AUAR, especially in Appendix F) are that the capacity of the FIG in the Ramsey area is sufficient to handle the existing and anticipated future withdrawals, with limited effects on the overlying materials. I am not sure if the observations made in the report are due to a higher inherent transmissivity, greater natural and pumping -induced recharge, or some combination of these factors, than is observed for the FIG elsewhere, but I would point out that the properties of the FIG are somewhat variable in the Metropolitan Area. Therefore, I would encourage the City to make itself aware of ongoing research being conducted by the Minnesota Geological Survey and the Metropolitan Council on the FIG and its water supply potential in the northwestern part of the Twin Cities Metropolitan Area (Chris Elvrum at the Met Council, 651-602-1066). Understanding the system dynamics of the FIG locally and regionally will help the City respond to (and perhaps avoid) complaints about its municipal pumping interfering with other local resources such as private wells and surface water bodies. Response: The City acknowledges the differences in the FIG within the region and is committed to undertaking the study identified in the AUAR to further its knowledge of the FIG behavior locally. The City will follow the progress of the MGS/Met Council study and will cooperate to the extent possible with all of the agencies involved in researching and regulating use of the FIG. The City recognizes the need to provide observation wells in the glacial aquifer and the need to perform both a pump test and long term trending analysis. It also concurs with the observation that the local transmissivities observed in Municipal Wells No. 3 and 4 are probably not representative of average conditions with the FIG. As a result, a more extensive hydrogeologic investigation of the local FIG capacity is planned prior to installation of additional wells. Comment 13.2: I would encourage the recommendation made on pages 13-7 and 13-8 (as well as Appendix F) that one or more nests of monitoring wells be placed in the area around the well filed to monitor water level changes in the glacial materials over time. I might also suggest that, if these wells were to be placed, a pumping test could be performed using one of the city's existing wells. Such a test would establish the nature of the hydraulic connection between the bedrock and the (surficial) drift and could probably be accomplished at little cost to the City. MDH staff and equipment are available to assist with such an effort because the results could be used to refine the wellhead protection planning efforts of the City. In the end, the kind of data generated from long term monitoring and from pumping tests will be of greater value in establishing the effect, if any, of municipal pumping on groundwater elevations in the area than just about any other kind of data or analysis. 34-29