M-8 - CMReport -3-11-22

March 11, 2022 Doug Boldt City Administrator City of Tiffin 300 Railroad Street Tiffin, IA 52340 TIFFIN, IOWA TEST WELLS 5A & 5B RECOMMENDATION FOR PRODUCTION WELL PRELIMINARY TEST RESULTS Shawver Well Company, Inc. has completed both test wells and has submitted water quality samples for testing. Results that are available to date have been added to the table enclosed with this letter. City staff also collected samples during test pumping to gather preliminary data. This information was combined with the laboratory data to evaluate which well would be the preferred option for conversion to a production well. Staff water quality testing results were reported as follows: <table> <tr> <th>SITE 5A (SOUTH OF RAILROAD)</th> <th>SITE 5B (SOCCER FIELD)</th> </tr> <tr> <td>30 GPM PUMPING RATE</td> <td>60 gpm Pumping Rate</td> </tr> <tr> <td>726 HARDNESS</td> <td>560 Hardness</td> </tr> <tr> <td>0.50+ AMMONIA</td> <td>0.50+ Ammonia<br>0.055 Manganese</td> </tr> <tr> <td>0.26 IRON</td> <td>0.40 Iron</td> </tr> <tr> <td>7.30 PH</td> <td>7.22 pH</td> </tr> </table> Test results obtained to date from both Staff testing and laboratory results indicate that water from either well will need to be treated to remove iron and to soften the water. In addition, both wells contain ammonia which will need to be considered when adding disinfectant to the water. Pumping rates were low for both wells with well 5B pumped at double the rate of Well 5A. Both test wells produce water at a rate much lower than desired for the production well. It is not uncommon to see lower production rates following construction of a well into the Silurian formation. Typically, the well will respond to acidization which will result in increased production. Acidization is not recommended at the test well phase since the test well will need to be drilled out to convert to the production well. Following review of the water quality information and pumping rates of the two test wells, Veenstra & Kimm, Inc. recommends proceeding with Site 5B at the soccer field for conversion of the test well to a production well. The initial pumping rate was higher, the hardness was lower and the location is at a higher elevation that is less prone to flooding.