Laserfiche WebLink
March 2, 2020 <br />Project 19-460 <br />Jackson Hills Residential Suite <br />Phases II- IV <br />Elk River, Minnesota <br />We recommend the bottom of the excavation be observed by a soils engineer or a qualified <br />technician to verify that native, competent material has been reached. We recommend the <br />excavation be oversized one foot for every foot of fill required to reach planned grade (1:1 <br />oversizing). Soils can change dramatically over short horizontal distances, therefore the <br />recommended excavation depths should be used as a guide. Since the timing and execution of the <br />excavation is critical, we recommend full time observation of the excavation and filling to ensure <br />all of the organic soils are removed to a clean bottom. <br />After removal of the peat and any unsuitable soils, we recommend imported, clean, coarse sand or <br />sand and gravel mix with less than 5% passing a number 200 sieve and less than 50% passing a <br />number 40 sieve be placed and compacted to bring the building and pavement areas to grade <br />Construction Dewatering: <br />Dewatering will be required for utility installation at depths below the groundwater elevations <br />shown on the borings logs. It is our opinion that a series of well points may be best suited for <br />dewatering the sand (SP, SP-SM) soils. We recommend that any standing water be removed <br />from the utility trenches prior to backfilling. In addition, we recommend that any utility trench <br />backfill material placed in standing water consist of clean sands with less than 5% passing the <br />number 200 sieve. <br />Structural Fill: <br />The imported soils specified above consisting of poorly graded sands (SP) are considered <br />excellent material for use as structural fill. These soils are not highly susceptible to moisture <br />variations and are free draining. They are easy to compact using vibratory compaction equipment <br />if they are near optimum moisture. <br />We recommend that any imported fill consist of mineral soils meeting the following <br />requirements. No organic soils, roots, stumps, logs, brush, etc. should be used as structural fill <br />below any foundation or pavement section. We recommend that all fill material be free of soft, <br />Page 6 <br />