1984-08-01 Regular Meeting (2) - Laserfiche WebLink

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• Division of Public Works • Mr. Jerry Hodge July 19, 1984 Page 3 • Woodward-Clyde Consultants Typical time required from a notice to proceed to completion of "Attachment 11" geotechnical report is approximately 2 months. However, we anticipate that•additional consultation with DPW and FIDR and meetings with the TDS may be necessary after completion of the report. Because of the presence of growth faults in the general area of this site and some evidence that a fault may exist on the property south of the site, some additional geological study will be required relative to the the fault issue. We will try to develop sufficient evidence from existing data (additional aerial photos, geophysically logged borings, etc.) to demonstrate that no active growth faults cross the site. Gathering and interpretation of this type of evidence is reasonably straight-forward and should be budgeted at $1,500 to $3,000. If, however, this type of study does not satisfy the TDH or if intervener claims must be refuted, a more extensive fault study may be required. The more extensive study, commonly referred to as a "Second Phase" study, requires a series of deep geophysically logged borings in order to check for offsets of geologic units (direct evidence of faults). • A second phase fault study would be conducted if required to satisfy the TDH or in defense of the permit application. That study would be conducted to verify a fault does not exist on the proposed landfill site or is not present within some distance from the proposed site such that it would affect the site. We anticipate that our work would include the following: o Conduct a field study consisting of geophysically logged boring holes approximately 300 ft deep along traverses normal to suspected fault directions; and o Prepare a report outlining our findings with appropriate maps to illustrate the location of borings, any fault locations, and hazard zones. The most reliable method of establishing fault locations is by geophysically logged boreholes in lines approximately normal to a fault. Typically, three to five boreholes per line are required to establish fault offset with any degree of reliability. A single line of borings may be suitable to resolve the presence or absence of a fault along any one boundary. However, two or more lines of borings may be required to show an absence of faulting on a property, particularly if it is necessary to define the distance to a fault that is nearby but offsite. LJ