COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

Subject: Victoria Island CCWD Alternative Intake Geotechnical Work Plan The purpose of this memo is to provide a summary of additional geotechnical fieldwork that Hultgren-Tillis Engineers would like to complete in support of preliminary engineering for the subject project. Cone Penetration Testing The Cone Penetration Test (CPT) method is minimally intrusive test, in which a 1.7 inch diameter probes are "pushed" directly into the ground at a constant rate, without drilling a borehole. Electronic sensors mounted inside the probe, called a penetrometer, provide a continuous record of the response of the soil to penetration. Computerized display and recording of data allow immediate evaluation of subsurface conditions. The CPT equipment is mounted on the 20-ton truck. A support truck and/or trailer transports grouting equipment to backfill the 1.7-inch diameter holes. No cuttings are generated. The work is typically done with a two-person crew. Hultgren - Tillis Engineers may have one of their engineers on the site at the same time. Most CPT's will take less than two hours. The deepest CPT at the Intake Structure site may take six to eight hours. CPT's for the Intake Structure and Setback Levee: CPTs would be completed in the proposed area for the intake structure site for possible differences in subsurface conditions along the levee that could affect cost or schedule. Three CPTs at approximate spacing of 1000 feet will be used to obtain additional soil profile data, as shown in the attached figure. Each of the CPTs will extend about 60 feet below the levee crest (to near Elevation -50 feet) Based on field information obtained during the testing, four additional CPTs would be completed for the Intake Structure and Setback Levee. These CPTs would include one at 100 feet deep from the levee crest, one CPT 60 feet deep between the toe ditch and the toe of the levee, and possibly two additional CPTs at 60 feet deep between the existing toe ditch and the farmed field. CPTs for the Pipeline Alignments: CPT for potential pipeline alignments will be 25 to 40 feet deep. As show on the attached figure, for the "indirect route" one CPT will be completed on the N-S leg of the alignment and another on the E-W leg. For the "direct route", two CPTs will be completed. CPT exploration for the pipeline alignments will be completed on existing farm roads, and will not encroach on the fields. All locations would be coordinated with the Farm Manager.