DRAFT <br />installed with a minimum center-to-center spacing of 4 feet. All anchors should be <br />equipped with appropriate corrosion protection measures. Prior to installing production <br />anchors at the site, at least one verification-test anchor should be installed near the <br />production-anchor locations. The verification-test anchor should be load-tested to <br />confirm the design capacity of the anchors and evaluate the optimum length of the bond <br />zone and load-deflection behavior of the anchors. The verification anchor should be tested <br />to a minimum of 200% of the maximum allowable design capacity in accordance with <br />applicable portions ofASTM D3689. We also recommend proof testing a minimum of 10% <br />of the production anchors to 150% of the design load. A successful verification or proof <br />test will typically sustain the test load for at least 10 minutes with less than 0.04 inch of <br />movement. In addition, the measured deflection at the design load needs to be less than <br />the maximum allowable deflection specified by the structural engineer. Corresponding <br />deflections of the mat foundations should also be reviewed during design, and the ground <br />anchor loading should be included in the mat foundation analyses. <br />5.5 Floor Support <br />All floor slabs should be established in relatively firm, undisturbed soils that are free of <br />organics and other debris. In our opinion, the fill soils encountered during this <br />investigation are generally suitable for floor support; however, this should be reviewed <br />during construction based on the actual conditions disclosed. To provide uniform floor <br />support and a capillary break to reduce the risk of damp flooring, all slab-on-grade floors <br />established near finished site grades should be underlain by a minimum 8 inches of free- <br />draining, clean, angular drain rock. Any floor slabs that will be established below finished <br />site grades and designed to be fully drained should be underlain by a minimum-12-inch- <br />thick layer of drain rock equipped with underslab drainage systems following the <br />recommendations provided in the Embedded Structures section of this report. The drain <br />rock should have a maximum size of 1.5 inches and less than about 2% passing the No. <br />200 sieve (washed analysis). In our experience, 11/2- to 3/4-inch crushed rock has worked <br />well for this purpose. To improve workability, the drain rock should be capped with at least <br />2 inches of more finely graded rock, such as 3/4-inch-minus crushed rock. The rock section <br />should be placed in one lift and compacted to at least 95% of the maximum dry density <br />as determined by ASTM D698 or until well keyed. In areas where floor coverings will be <br />provided or moisture-sensitive materials are stored, it is also appropriate to install a vapor- <br />retarding membrane in accordance with the manufacturer's recommendations. <br />To evaluate isolated point loading on the floor slabs, we recommend assuming a <br />coefficient of subgrade reaction, k, of 150 pci to characterize the subgrade support with a <br />minimum of 10 inches of compacted crushed rock beneath the slabs as recommended. <br />This value assumes the underlying subgrade could consist of silty soil. In areas where the <br />underlying subgrade consists of gravel and cobbles, a value of up to 400 pci is appropriate. <br />GRI #6497-A - 2.MO Indoor Football Practice Facility Page 17 <br />August 26, 2021 <br />