Laserfiche WebLink
603284-001 <br />5.1.4 Trench Backfill <br />Trench excavations above pipe bedding may be backfilled with onsite soils <br />under the observation of the geotechnical consultant. All fill soils should <br />be placed in loose lifts, moisture conditioned as required and compacted <br />to a minimum of 90 percent relative compaction based on ASTM Test <br />Method D 1557-10. Lift thickness will be dependent on the equipment <br />used as suggested in the latest edition of the Standard Specifications for <br />Public Works Construction (Greenbook). The fill soils should extend to the <br />bottom of the aggregate base for new pavement, or to finished grade. <br />5.1.5 Corrosion Protection Measures <br />The chemical analysis test results for the onsite soils from our <br />geotechnical exploration are included in Appendix C of this report. The <br />test results are also summarized in the table below. <br />TABLE 3: CORROSIVITY TEST RESULTS <br />Test Parameter <br />Test Results <br />B-1 B-4 <br />General Classification of <br />Hazard <br />Water-Soluble Sulfate <br />in Soil (ppm) <br />Water-Soluble <br />Chloride in Soil (ppm) <br />Negligible sulfate <br />89 44 exposure to buried <br />concrete <br />Non-corrosive to buried <br />62 43 concrete (per Caltrans <br />Specifications) <br />pH 7.45 7.30 Mildly Alkaline <br />Corrosive to moderately <br />Minimum Resistivity corrosive to buried <br />3,100 8,000(saturated, ohm-cm)ferrous pipes (per <br />ASTM 1) <br />ASTM STP 1013 titled Ellect of So# Characteristics on Corrosion (February, 1989) <br />The results of the resistivity test indicate that the soil is corrosive to <br />moderately corrosive to buried ferrous metals. Based on the measured <br />water-soluble sulfate from the soil sample, concrete in contact with the soil <br />is expected to have negligible exposure to sulfate attack per ACI 318-08. <br />-21 - <br />Leighton