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• - 13 - <br />(7) Ail pier holes should be thoroughly cleaned prior to placing <br />concrete. Where sand and gravel subsoils overlie bedrock or where <br />high seepage rates are encountered, casing will probably be required <br />in order to properly clean, dewater and Inspect the holes. <br />(8) {t is recommended that all piers be adequately reinforced for <br />tension. Continuous reinforcement, top to bottom, should be used <br />(n piers drilled into the claystone. <br />Spread Footln~s on Bedrock: <br />(1) Footings placed on the unweathered, undisturbed bedrock may be <br />designed fora maximum Boll pressure of 12,000 psf. <br />(2) Footings should also be designed fora minimum dead load pressure <br />of ;,000 psf. <br />(3) Narrow footings for walls retaining soli or rock should be doweled <br />into the rock to develop shear to resist the lateral force. <br />(4) Footings should be placed only on firm and undisturbed bedrock. <br />In the event the bedrock surfaces have been loosened by blasting <br />or excavating, the boss materiel should be removed and lean <br />concrete placed to reievel the area. <br />(5) Footings should also be placed below frost depth. In this area, <br />tho anticipated level of frost penetration (s 4 feet. <br />Spread Footings on Natural Soils: <br />(1) Spread footings placed on the natural Solis can be designed for a <br />maximum soft pressure of 4,000 psf. Under this pressure, maximum <br />~' <br />settlement is estimated to.ba approximately 1} inches and differen- <br />• tial movement of about 1 Inch. Results of time consolidation <br />r: V' '~ ~. <br />.. <br />