DRAFT <br />Other measures that should be implemented to reduce the risk of localized failures of <br />temporary slopes include (1) using nonwoven geotextile fabric to protect the exposed cut <br />slopes from surface erosion; (2) providing positive drainage away from the tops and <br />bottoms of the cut slopes; (3) constructing and backfilling embedded structures as soon <br />as practical after completing the excavation; (4) backfilling overexcavated areas as soon as <br />practical after completing the excavation; and (5) periodically monitoring the areas around <br />the top of the excavation for evidence of ground cracking. It must be emphasized that <br />following these recommendations will not guarantee sloughing or movement of the <br />temporary cut slopes will not occur; however, the measures should serve to reduce the risk <br />of a major slope failure. It should be realized that blocks of ground and/or localized slumps <br />may tend to move into the excavation during construction. <br />5.3.4 Utility Trench Excavations <br />In our opinion, trenches less than 4 feet deep that do not encounter groundwater can <br />typically be cut vertically and left unsupported during the normal construction sequence, <br />assuming trenches are excavated and backfilled in the shortest practical sequence. It <br />should be noted, however, that some sloughing or raveling of the trench sidewalls may <br />occur, particularly in the gravel and cobbles. Excavations more than 4 feet deep should be <br />laterally supported or sloped at 1 HA V to 1.5H:1 V or flatter. In our opinion, adequate lateral <br />support for the trench sidewalls may be provided by common methods, such as the use <br />of trench shields or hydraulic shoring systems. <br />5.3.5 Boulder Excavation <br />Although not encountered in the explorations completed for this project, our experience <br />in the project area indicates boulders could be present in the alluvial gravel and cobbles. <br />Depending on the rock composition, relative weathering, hardness, and size of the <br />potential boulders, it may be possible to complete excavation of boulders by ripping with <br />a large track-mounted hydraulic excavator equipped with a rock bucket and rock teeth. <br />However, it should be anticipated that some rock chipping or other specialized methods <br />of excavation may be required if very large and/or hard boulders are encountered. Project <br />plans, specifications, and bid items should address the uncertainty associated with <br />encountering boulders in excavations completed on site. <br />5.4 Foundation Support <br />5.4.1 General <br />In our opinion, support for the new structures can be provided by shallow foundations as <br />planned, provided the recommended foundation design criteria and estimated <br />settlements provided below are considered acceptable. The allowable bearing pressures <br />used for design of shallow foundations is typically controlled by tolerable settlements as <br />opposed to bearing capacity considerations. In this regard, we anticipate the new <br />GRI #6497-A - 2.MO Indoor Football Practice Facility Page 12 <br />August 26, 2021 <br />