DRAFT <br />5.6 Embedded Structures <br />5.6.1 Lateral Earth Pressures <br />Although basements or other embedded structures are not currently planned for the <br />project, we anticipate retaining walls may be used to accommodate overall site grading. <br />The following sections of this report are applicable to site retaining walls and embedded <br />building walls; however, any potential embedded structures should be reviewed by GRI, as <br />additional considerations and supplemental recommendations may be appropriate based <br />on site conditions. Design lateral earth pressures for embedded walls depend on the <br />drainage condition provided behind the wall and the ability of the wall to yield. The two <br />possible conditions regarding the drainage condition behind a wall are (1) backfill that is <br />fully drained and therefore does not induce hydrostatic pressures on the wall, and (2) <br />backfill that is not fully drained and therefore may induce hydrostatic pressures on the <br />wall. The two possible conditions regarding the ability of the wall to yield are (1) a wall <br />that is laterally supported at its base and top and therefore unable to yield, and (2) a wall <br />that is not laterally restrained and yields by sliding or tilting about its base. The <br />recommendations provided below assume embedded walls will be backfilled with <br />structural fill. Heavy compactors and large pieces of construction equipment should not <br />operate within 5 feet of any embedded walls to avoid the buildup of excessive lateral <br />pressures unless the walls have been designed to accommodate these pressures. <br />Otherwise, compaction close to the walls should be accomplished using lightweight, hand- <br />operated equipment. <br />In areas where the wall backfill will be fully drained yielding and non-yielding walls <br />retaining horizontal backfill can be designed based on equivalent fluid unit weights of 35 <br />pcf and 50 pcf, respectively. In areas where the wall backfill will not be fully drained, <br />yielding and non-yielding walls can be designed based on equivalent fluid unit weights of <br />80 pcf and 90 pcf, respectively. To account for seismic loading conditions, the static earth <br />pressures provided above should be increased by about 5 pcf and 15 pcf for yielding and <br />non-yielding walls, respectively. Additional lateral pressures due to surcharge loadings in <br />the backfill area can be estimated using the guidelines provided on Figure 4. At a <br />minimum, we recommend using a uniform lateral surcharge pressure of 100 psf to account <br />for construction equipment operating behind embedded walls. This temporary <br />construction surcharge does not need to be included when evaluating seismic loading <br />conditions. Resistance to lateral and vertical driving forces can be evaluated following the <br />recommendations provided in the Foundation Support section of this report. <br />If embedded structures are not fully drained using subdrainage systems, it should be <br />assumed that the groundwater level at the site could rise to the ground surface during the <br />design life of the project. Embedded structures that are not fully drained should also be <br />GRI #6497-A - 2.MO Indoor Football Practice Facility Page 18 <br />August 26, 2021 <br />