1001 W CASINO RD BASE FILE 2018-01-01 MF Import

actual trench widthe may be greater than the minimum apecified. The bottom of the excavation ahould be carefully cleaned of all loose material prior to concrete placemeht . Covering the teeth of the backhoe bucket with a emooth cutting edge can qreatly speed thie operation. Vertical reinforcinq eteel ahould aleo be included to tie the footinq to the concrete backfill in the trench. In order to utilize rock trenches for footing support, the trenchea muet be excavated to a minimum width of 4 feet and extend down to the bearing aoils. Backfill material ahould coneist of 2 to 4 inch cruahed rock. The use of a larger, track-mounted backhoe With the teeth covered will qreatly speed trench excavation over the use of a conventional, rubber- tired backhoe. To determine uhen euitable bearing hae been achieved and to verify proper rock and/or concrete placement , a qualified geotechnical enqineer / engineering geologiat from our firm muet be preaent on a full time baeis during trench excavation and backfill. After the bearing atratum hae been reached, the trench may be backfilled. If rock trenchee are utilized, tho cruehed rock muet be tamped into place to achieve a tightly packed maDa. Thie may be done with either a "Hoepac" type compactor mounted on a backhoe or with the bucket of the backhoe itaelf. The contractor ahould note that due to the potential for caving, the actual trench width may be greater than apecified. Aleo, if eignificant water ia encountered, a pump may be required to control aeepage ao that the bearing level can be vieually determined. Spread footinge , deaigned as per 9ection 8.1, spread Eootings, may then be placed on approved lean mix concrete or rock trenchee ae described above. 8_3 Drilled Piere Inatallation of drilled piera conaiate of placinq reinforced, atructural concrete in pre-drilled, open holea . Eighteen-inch diameter drilled piere embedded a minimum of 5 feet into the underlying till (Unit 31 , or advance outwash depoeita (Unit 4) , would be capable of aupporting loada on the order of 15 tone per pier. succesaful inatallation of a pier syatem requiree that the aedimente will not cave into the holes after auger xithdrawal or while concrete is being placed. if the holee will not etay open, it may be necessary to case the holes or use a bentonite alurry. Based on obaervationa during our field exploration, it ie our opinion that the holes will generally etay open during and immediately following augering, provided that seepaga into the holee ie not greater than was observed in our exploration piLa. It may be neceseary to uae a flexible drop chute or concrete pump with hoee extended to the bottom of the hole to aseure that any water ia adequately dlaplaced during concrete placement . We would aleo recommend that the contractor be prepared to place concrete into each hole immediately followinq auger uithdrawal rather thau attempt to leave several 9 �{(,y� �y