Agenda - Council - 10/08/2019 - Laserfiche WebLink

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Public Water Supplier: Ramsey (1020035) Date: 12/15/2017 The DWSMA remains unchanged and reflects the capture zone that would result from the use of a time of travel of 12 years approximately. Step 11 — Is the WHPA delineation method that was used for the current plan still adequate to address modifications that have been identified in any of the previous steps? • Yes. The original model is based on a MODFLOW model developed by the consultant for the Tunnel City and Wonewoc Sandstones. It was imported in a recent version of the pre- and post -processor GMS (ver. 10.3). The model runs in MODFLOW 2000 ❑ No (update the delineation method/model as needed — there must be a runnable version of the model in a useable code so results can be validated). Step 12 - Do the existing DWSMA boundaries need to be re -defined? • No. The new WHPA has been redefined using an updated version of the 2007 model. It was redefined in the same manner as in 2007by concatenating the capture zone results of 11 scenarios. The 2017 WHPA is still contain within the existing DWSMA. Congratulations — you may use the EZ amendment form to document the amended Part 1 and file this worksheet to document the basis for using it. ❑ Yes, the amended WHPA does not extend beyond the current DWSMA boundaries; however the existing DWSMA boundaries can be reduced based on new information such as parcel data. Congratulations — you may use the EZ amendment form to document the amended Part 1 and file this worksheet to document the basis for using it. ❑ Yes, the amended WHPA does extend beyond the current DWSMA boundaries. Create a new Part 1 report. Step 13 — Does information exist to support an updated DWSMA vulnerability assessment? ❑ No, the geographic extent of the DWSMA is not changing and no new hydrogeologic, chemical or isotopic data exist to justify a change. • Yes, the geographic extent of the DWSMA is changing and/or new hydrogeologic, chemical or isotopic data exist to justify a change. L-scores were regenerated at wells using the CWI data available in 2017. City wells were analyzed for tritium in 2012 and 2017. Review of the existing geologic information and recent tritium sampling at the city wells did not change the DWSMA vulnerability status around Wells 3, 4, 5, 6, 7, and 8. The rising tritium in Well 1 argues for a more protective DWSMA vulnerability rating. Therefore, the DWSMA vulnerability status around Wells 1 and 2 changed from low to moderate. 8 V1.0 2/2013