Laserfiche WebLink
Fifty percent of the excavated soil and all of the fractured and massive bedrock were spoiled <br />inside the perimeter of the slurry wall trench except between approximately station 18+00 and <br />ending at approximately station 25+00 where these material were spoiled to the outside of the <br />trench. Between these stations, Loveland Ready Mix had excavated an approximate 60-ft wide <br />and approximate six feet deep trench along the alignment. The trench caused WRS Compass to <br />change the location of the spoils. <br />The Contractor excavated to the top of the massive bedrock and then provided a sample of this <br />rock to Lyman Henn field personnel for verification. Once Lyman Henn verified that the <br />massive bedrock had been reached, the depth to the bottom of the slurry trench was measured <br />by the Contractor at three locations (start, end, and one near the center) along the 30-ft set. <br />These depths were recorded as the final elevation for the slurry wall key, in ten-foot intervals. <br />The contractor then cleaned out the entire segment, by methodically dragging the bucket across <br />the trench bottom before starting a new interval. The elevations of the top of bedrock and the <br />bottom of trench are presented in Table Ell. <br />Excavated alluvium was primarily clayey soils underlain by sand with gravel or gravel with <br />sand. <br />Lyman Henn and the Contractor monitored the in-trench slung level during excavation. The <br />excavation ceased when slurry levels dropped below two feet from the top of the working <br />' platform. The Contractor introduced fresh slung or placed backfill as appropriate, until the <br />slung level in the trench was acceptable. <br />' 3.4 Soil-Bentonite Mixing and Placement <br />3.4.1 Backfill Components <br />' The slurry wall trench was backfilled with soil-bentonite. This backfill consisted of a <br />mixture of select backfill (excavated alluvium), powdered bentonite, and bentonite <br />slurry. The backfill batching was designed to result in a minimum of 30 percent fines <br />(soil material passing the #200 sieve). Table IV presents a summary of backfill testing. <br />Bentonite used for backfill was delivered to the site in four thousand-pound bags. <br />' Bentonite slurry used in the backfill was obtained from the slurry trench using the <br />excavator. <br />3.4.2 Backfill Mixing and Placement Procedures <br />Backfill was batched on the working platform between centerline of the slurry wall and <br />' the borrow material berm. The borrow material berm was previously placed to <br />supplement the backfill material and was composed of the specified clayey alluvium. <br />The powdered bentonite was distributed across the working platform at a calculated rate <br />' to result in 2% dry-added bentonite content in the backfill. A bulldozer would mix the <br />backfill by tracking back and forth over the material until the proper consistency was <br />achieved after the bentonite slurry was added to the mix of soil and powdered <br />' bentonite by a trackhoe. The bulldozer would place the backfill by back-dragging it <br />on the top of the backfill slope. Backfill was placed by a dozer as excavation was <br />G:\PROJECCS\107021-000 Loveland Ready Mix Slurry Wall\R. Records and Correspondence\R.l1 Reports\As-Built report stu"s-built reportFnal.doc 4