320.6 Slide Investigations

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Slope Stabilization and Erosion, Agents
Report 2001
Slope Stabilization, Plastic Pins
Summary 2003
Report 2007
Report 2003
Summary 2005
Report 2003
Report 2000
Summary 2000
Slope Stabilization, Soil Nail
Summary 2006
See also: Research Publications

This guidance establishes operational procedures for slide investigations.

320.6.1 Responsibility

Slide investigations may be performed by either district Construction and Materials personnel or by personnel assigned to the Geotechnical Section of Construction and Materials. Slides which will require specialized investigative techniques, such as undisturbed sampling, testing and stability analyses, should be referred to the Geotechnical Section. Geotechnical personnel will be available for consultation in regard to those slides investigated by district personnel. Consultation, prior to completion of the report, is recommended for slides that are costly to repair and is requested for those slides that will be repaired by contract since the Geotechnical Section may later be asked to review the district recommendations.

320.6.2 Procedure

Requests for a slide investigation by Construction and Materials may originate at either the unit or district level. Those originating in the district should be by letter to the State Construction and Materials Engineer. The request should include a general description, location, final plans, history, urgency of repair, and any available subsurface information. In emergency situations, requests may be verbal subject to written confirmation. Before drilling operations can start it will be necessary for district personnel to lay out stationing, generate cross sections, clear utilities, and obtain permission from property owners if required. Stationing should be laid out every 100 ft. at the top, middle, and bottom of the slope using the same stationing as in the final plans. Flags should be set at these points with the station, offset, and elevation marked on them. While arbitrary stations should not be used, an arbitrary elevation may be used (for example, elevation top of slope equals elevation 100.0). Cross-sections should be generated every 100 ft. in the slide area and for at least 100 ft. either side of the slide area. Cross-sections should extend from at least the top to the bottom of the slope even if this may be off of right of way. Cross-


sections should agree with stationing laid out in the field and right of way, edge of pavement, and either baseline or centerline should be labeled.

320.6.3 Report

Reports shall be in letter form with test data and boring logs attached. Distribution of Construction and Materials reports is individually considered. The District Engineer or unit engineer requesting the investigation will receive the original and copies will be sent to any concerned units. Reports of investigation of slides anticipated to be repaired by contract, whether originating in a district or the Geotechnical Section, should have distribution equivalent to that of a preliminary geotechnical report plus Maintenance. The State Construction and Materials Engineer is to be furnished a copy of all reports of slide investigations conducted by district Construction and Materials personnel.