Agenda - Council - 10/24/2017 - Laserfiche WebLink

Home

s) Pearson Place Ramsey, Minnesota NTI Project No. 17.62064.100 Redoximorphic soil features (soil staining) was obscured due to the heavy irrigation in the farm field. We anticipate that the seasonal high groundwater would be comparable to this level, however, due to the above average precipitation over the year as well as inputs from irrigation. 2.4 Laboratory Test Program Our analysis and recommendations within this report are based upon our interpretation of the sampled soils, laboratory test results, and experience with similar soils from other sites near the project. The results of such tests are summarized on the boring logs or attached laboratory test reports. 2.5 Infiltration Test Results In total, two (2) DRI tests were completed (see appendix for location). Test #1 was completed approximately 3 feet below existing grade, just below the agricultural till layer. In general accordance with the Minnesota Pollution Control Agency Stormwater Manual, and the results of our DRI test, the design infiltration rate for this test depth was found to be 0.25 inches per hour. Test #2 was completed approximately 5 feet below existing grade. In general accordance with the Minnesota Pollution Control Agency Stormwater Manual, and the results of our DRI test, the design infiltration rate for this test depth was found to be 1.5 inches per hour. NTI perform an additional test on September 1, 2017. The design infiltration rate for that test was found to be 2.75 inches per hour. The MPCA recommends using an average of values for tests in the same stratum. The average would be approximately 2 inches per hour. 2.6 Low Floor Elevation As mentioned above, we encountered groundwater at elevations of 848.5 and 849. Redoximorphic features (soil staining) were obscured by the heavy irrigation that occurred during the farming process; however, due to the relatively wet year and regular irrigation, we anticipate that this elevation will be similar to the seasonal high water elevation. It is our opinion that a low floor elevation of 854 would provide a sufficient buffer (at least 5 feet) against transient groundwater conditions. Page 2 of 3